• J. Wenninger
  CERN, Geneva

Beam commissioning of the LHC started with injection tests in August 2008, and a circulating beam was obtained in little over 3 days in September 2008. Unfortunately a powering incident in one the eight LHC sectors set an abrupt end to the beam commissioning in 2008. This talk will review the LHC beam commissioning achievements. It will describe the repair the LHC sector affected by the incident and present the measures that have been taken to avoid similar incidents in the future. The commissioning steps foreseen for the 2009 run and towards LHC design performance will be outlined.

Slides

• Z.T. Zhao, H. Ding, H.G. Xu
  SINAP, Shanghai

The Shanghai Synchrotron Radiation Facility (SSRF) is an intermediate energy, third generation light source. In December 2007, electron beam was stored and accumulated in the SSRF storage ring. Since then the accelerator commissioning and beam line installation have continued toward the scheduled user operation from May 2009 onwards. This paper presents an overview of the SSRF status and preparations for user operations.

Slides

• W. Meng, Y. Hao, A.K. Jain, V. Litvinenko, G.J. Mahler, J.E. Tuozzolo
  BNL, Upton, Long Island, New York

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

eRHIC, a future high luminosity electron-ion collider at BNL, will add polarized electrons to the list of colliding species in RHIC. A 10-to-30 GeV electron energy recovery linac will require up to six passes around the RHIC 3.8 km circumference. We are developing and testing small (3-to-5 mm gap) dipole and quadrupole magnets and vacuum chambers for cost-effective eRHIC passes. We are also studying the sensitivity of eRHIC pass optics to magnet and alignment errors in such a small-magnet structure. We present the magnetic and mechanical designs of the small gap eRHIC components and prototyping test results.

• G. Danby, J.W. Jackson, A.K. Jain, M. Rehak, O. Singh, J. Skaritka, C.J. Spataro
  BNL, Upton, Long Island, New York

Funding: US DOE Office of Basic Energy Sciences

Discrete corrector magnets are used for the 230 horizontal and vertical steering magnets in the NSLS-II storage ring. A unique design incorporates both dipole and skew quad correctors for(DC) steering in the same magnet. Separate AC (orbit feedback) correctors have also been designed. Comparison with alternate designs are presented as well as prototype measurements

• C.J. Spataro, A.K. Jain, M. Rehak, J. Skaritka
  BNL, Upton, Long Island, New York

Funding: US DOE Office of Basic Energy Sciences

The Sextupole magnets for the National Synchrotron Light Source (NSLS-II) have stringent performance requirements. These magnets have a faceted pole profile departing from the classic shape due to constraint imposed by the vacuum tube. Three different geometric features were used as parameters to minimize unallowed harmonics. Prototypes were measured and have confirmed the good field quality.

• T.J. Zhang, Y.L. Lu, C. Wang, S.M. Wei, J.J. Yang, H.J. Yao, J.Q. Zhong
  CIAE, Beijing

CYCIAE-100 is a 100 MeV, 200 muA H^- cyclotron being constructed at CIAE. The tolerance of the magnetic field is as tight as 1.2 Gauss for isochronous field and 2 Gauss for first harmonics. Due to the absence of coil adjusting in this machine, a measure that helps to achieve a more compact structure (435 ton for the main magnet), the imperfection hence becomes a much more critical factor in our consideration. The effects by the various kinds of imperfection are investigated numerically and the imperfection fields are predicted for beam dynamics simulation, serving as a basic guidance in the magnet construction for CYCIAE-100. Some of the important results will be reported in this paper, including

1. the deformation of the main magnet by the gravity itself, 480 ton EM force and 120 ton vacuum pressure,
2. segregation, inclusion and contraction cavity induced by the casting procedure,
3. fabrication and assembling tolerance, and
4. thermal deformation.

• T.J. Zhang, C.J. Chu, G.F. Song, S.M. Wei, J.Q. Zhong
  CIAE, Beijing
• J.J. Yang
  TUB, Beijing

To limit the cost for the main magnet of a compact cyclotron CYCIAE-100, the cast steel is used for the top/bottom yoke and return yoke. The imperfection may not be ignored and the harmonic coils on the return yokes will make the fields reaching the requirements easier during the shimming. The centering coils will not only compensate the 1st harmonic fields at the center region, which is usually remain big, but also correct the off-center injection of the beam. The thermal deformation and the vacuum pressure may change the fields distribution during the machine operation and therefore It is necessary to use trim coils to adjust the fields. We arrange the trim coils inside the two opposite valleys of the main magnet. The second harmonics from the trim coils are not big eough to affect the beam dynamics significantly from the beam dynamics study. In this paper, the effects of correction coils of three types are presented. The detail configuration of the correction coils is introduced in the paper as well. One concern is the potential interference of some water cooled coils could have with vacuum. Some experience for the coils inside the high vacuum tank is tested and the results are given.

• Y. Iwashita, T. Sugimoto
  Kyoto ICR, Uji, Kyoto
• M. Masuzawa, T. Tauchi, K. Yokoya
  KEK, Ibaraki

Funding: Work partially supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (A), 18204023(2006)

Although the base line technology of the Final Focus Doublet for ILC is superconducting magnet, which is supposed to be conventional, the slender structure may be suffered from its vibration. The permanent magnets, however, do not have any vibration source in it at the steady state. The five-ring-singlet configuration, proposed by R. L. Gluckstern adds 100% strength adjustability to permanent magnet quadrupole (PMQ) lens. A prototype of this lens is fabricated and under evaluation. It was originally designed for ILC that also has the extra hole for the outgoing beam. In order to realize the beam test at ATF2, the inner bore is enlarged from D20mm to D50mm to clear the background photons from Shintake-Monitor. The magnet is described.

• J.C. Huang, C.-H. Chang, C.-S. Hwang
  NSRRC, Hsinchu

Abstract A 3-GeV electron-storage ring with tiny emittance has been designed for the Taiwan Photon Source (TPS) that will provide one of the world's brightest synchrotron x-ray sources. Sextupole magnets for the booster ring (BR) serve to correct the chromaticity of the beam particles. As an AC power supply is generally used in a booster ring to raise beam particles to a required energy, a power supply at 3 Hz AC is used to charge the sextupole magnet, which would induce eddy currents in the vacuum chamber resulting in a magnetic multipole field. As an aspect of the magnet design, decreasing the effect of an eddy current on the homogeneity of the magnetic field, the geometry and material of the chamber must be considered. We demonstrate the effects of an eddy current on the homogeneity of a magnetic field for a vacuum chamber of various types, and we discuss the magnetic circuit and the conductor design of the booster-ring sextupole. Analysis of the multipole field and eddy-current loss were included to assure the accuracy of the magnetic circuit design.

• K. Yonehara, V.S. Kashikhin, M.J. Lamm, M.L. Lopes, A.V. Zlobin
  Fermilab, Batavia
• R.P. Johnson, S.A. Kahn, M.L. Neubauer
  Muons, Inc, Batavia

Funding: Supported in part by USDOE STTR Grant DE-FG02-07ER84825 and by FRA under DOE Contract DE-AC02-07CH11359

The helical cooling channel is proposed to make a quick muon beam phase space cooling in a short channel length. The challenging part of the helical cooling channel magnet design is how to integrate the RF cavity into the compact helical cooling magnet. This report shows the possibility of the integration of the system.

• M.A. Green, D. Li, S.P. Virostek, M.S. Zisman
  LBNL, Berkeley, California
• A.B. Chen, X.L. Guo, X.K. Liu, H. Pan, L. Wang, H. Wu, F.Y. Xu, S.X. Zheng
  ICST, Harbin
• D.J. Summers
  UMiss, University, Mississippi

Funding: This work is supported by funds under the “985-2” plan of HIT. This work is also supported by the Office of Science, US-DOE under DOE contract DE-AC02-05CH11231 and by NSF through NSF-MRI-0722656.

The superconducting coupling solenoid for MuCOOL and MICE will have an inside radius of 750 mm, and a coil length of 285 mm. The MuCOOL coupling coil is identical to the MICE coupling coils. The MICE coupling magnet will have a self inductance of 592 H. When operated at it maximum design current of 210 A (the highest momentum operation of MICE), the magnet stored energy will be about 13 MJ. These magnets will be kept cold using a pair of pulse tube cryocoolers that deliver 1.5 W at 4.2 K and 55 W at 60 K. This report describes the progress on the MuCOOL and MICE coupling magnet design and engineering. The progress on the construction of the first coupling coil will also be presented.

• S.P. Virostek, M.A. Green, D. Li, M.S. Zisman
  LBNL, Berkeley, California

Funding: This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231.

The Muon Ionization Cooling Experiment (MICE) is an international collaboration that will demonstrate ionization cooling in a section of a realistic cooling channel using a muon beam at Rutherford Appleton Laboratory (RAL) in the UK. At each end of the cooling channel a spectrometer solenoid magnet consisting of five superconducting coils will provide a 4 tesla uniform field region. The scintillating fiber tracker within the magnet bore tubes will measure the emittance of the muon beam as it enters and exits the cooling channel. The 400 mm diameter warm bore, 3 meter long magnets incorporate a cold mass consisting of two coil sections wound on a single aluminum mandrel: a three-coil spectrometer magnet and a two-coil section that matches the solenoid uniform field into the MICE cooling channel. The fabrication of the spectrometer solenoids has been completed, and preliminary testing and field mapping of the magnets is nearly complete. The key design features of the spectrometer solenoid magnets are presented along with a summary of the progress on the testing and magnetic measurements.

• D. Saez de Jauregui, S. Casalbuoni, A.W. Grau, M. Hagelstein, E.M. Mashkina
  FZK, Karlsruhe
• R. Cimino, M. Commisso
  INFN/LNF, Frascati (Roma)
• R. Weigel
  Max-Planck Institute for Metal Research, Stuttgart

Recent investigations with the cold bore superconducting undulator installed at ANKA indicate that the main contribution to the beam heat load is caused by electron bombardment. For a quantitative understanding of the problem a cold vacuum chamber for diagnostics has been designed. Among other important parameters (heat load, pressure, etc) this device shall monitor the spectrum of the low energy electrons bombarding the wall. In this contribution we report on the measurements of the spectrum of the low energy electrons bombarding the wall of the cold vacuum chamber in a room temperature region of the ANKA storage ring performed using a in house developed retarding field analyzer (RFA). The calibration of the RFA performed at the national laboratories of Frascati is also described.

• A. Madur, S. Marks, S. Prestemon, D. Robin, T. Scarvie, D. Schlueter, C. Steier
  LBNL, Berkeley, California

Funding: This work is supported by the Director, Office of Science, U. S. Department of Energy under Contract No. DE-AC02-05CH11231.

In 2006, the 30mm period In-Vacuum Insertion Device (IVID) was operational for the femtosecond phenomena beamline at the Advanced Light Source (ALS) of Lawrence Berkeley National Laboratory. Since then the IVID has been demonstrating unexpected behaviors especially at small gaps (minimum gap = 5.5mm). The main observations related to these issues are partial or total beam losses as well as sudden pressure increases while operating the IVID gap. This paper is reporting these observations and describes the investigations and the repair attempt performed on this insertion device.

• A. Hershcovitch, M. Blaskiewicz, W. Fischer
  BNL, Upton, Long Island, New York
• H.J. Poole
  PVI, Oxnard

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

Electron clouds have been observed in many accelerators, including RHIC at BNL. They can limit the machine performance through pressure degradation, beam instabilities or incoherent emittance growth. The formation of electron clouds can be suppressed with beam pipe surfaces that have low secondary electron yield. Also, high wall resistivity in accelerators can result in unacceptably high ohmic heating levels for superconducting magnets. These are concerns RHIC, as its vacuum chamber in the superconducting dipoles is made from relatively high resistivity 316LN stainless steel. The high resistivity can be addressed with a copper (Cu) coating; a reduction in the secondary electron yield can be achieved with a titanium nitride (TiN) or amorphous carbon (a-C) coating. Applying such coatings in an already constructed machine is rather challenging. We sta rted developing a robotic plasma deposition technique for in-situ coating of long, small diameter tubes. The technique entails fabricating a device comprising of staged magnetrons and/or cathodic arcs mounted on a mobile mole for deposition of about 5 μm (a few skin depths) of Cu followed by about 0.1 μm of TiN (or a-C).

• H.-C. Hseuh, L. Doom, M.J. Ferreira, C. Longo, V. Ravindranath, P. Settepani, S. Sharma, K. Wilson
  BNL, Upton, Long Island, New York

Funding: Work performed under the auspices of U.S. Department of Energy, under contract DE-AC02-98CH10886

National Synchrotron Light Source II is a 3-GeV, 792-meter circumference, high-flux and high-brightness synchrotron radiation facility being constructed at Brookhaven National Laboratory. The storage ring vacuum chambers are made of extruded aluminium and the bending magnet photons are intercepted at discrete photon absorbers. The design of the storage ring vacuum system will be presented, with emphasis on vacuum chamber design and fabrication, pumping arrangements, photon beam tracking and absorber positioning, and interface with other accelerator systems. The evaluation of the aluminium chamber prototypes and RF shielded bellows will also be described.

• X.T. Yang, D.Z. Guo, C.Y. Hao, S.J. Hou, Z.J. Hu, Y.S. Jia, M.L. Lou, S.M. Lv, X.L. Ma, J. Meng, Z.S. Nie, Z.W. Niu, W.S. Yang, Z.M. You, J.H. Zhang, Y.G. Zhao
  IMP, Lanzhou

The vacuum system of HIRFL is a large and complex system. HIRFL consists of two ECR ion sources, a sector focus cyclotron (SFC), a separate sector cyclotron (SSC) and a multipurpose cooling storage ring system which has a main ring (CSRm) and an experiment ring (CSRe). Several beam lines connect these accelerators together and transmit various heavy ion beams to more than 10 experiment terminals. According to the requirements of the ion acceleration and ion lifetime, the working pressure in each accelerator is different. SFC is nearly 50 years old. After upgrade, the working pressure in SFC is improved from 10E-6mbar to 10E-8mbar. The pressure in SSC which was built in 1980s reaches the same level. The cooling storage ring system with a length of 500m came into operation in 2007. The average pressure in CSRm and CSRe is 5E-12mbar and 8E-12mbar respectively. Different designs were adopt for vacuum system of dozens beam lines to meet various experiment terminals requirement. For instance, some shockproof measures have to be taken for the heavy ion microbeam facility. A clean and large throughput differential pumping system was built for the Gas-filled Recoil Separator and so on.

• E. Al-Dmour, D. Einfeld, M.J. Grabski, R. Martin
  CELLS-ALBA Synchrotron, Cerdanyola del Vallès

The vacuum system of CELLS is in the installation stage. The booster vacuum chambers have been assembled and baked out in a provisional laboratory ex-situ in the ALBA building and in less than two months (starting from February) all the booster vacuum system was installed inside the tunnel and under vacuum. All the storage ring vacuum chambers have been delivered and ready for installation, several chambers were tested at CELLS (tests include vacuum tests, dimensional check, magnetic permeability tests…etc). All the tools needed for the assembly of the storage ring vacuum chambers have been delivered and tested at CELLS to validate the assembly procedure. Concerning the standard vacuum components; all the gauges and residual gas analyzers were delivered, all the ion pumps and controllers are at CELLS, the NEG pumps, leak detectors, roughing stations and the UHV valves were delivered too.

• Y. Li, X. Liu, V. Medjidzade, M.A. Palmer, D.H. Rice, D. L. Rubin, J.J. Savino
  CLASSE, Ithaca, New York

Funding: Work supported by the National Science Foundation, the US Department of Energy, and the Japan/US Cooperation Program

In concert with the ILC global design effort, the CESR is being converted into ILC Damping Ring Test Accelerator. The vacuum system is undergoing staged reconfigurations to support both the CesrTA physics goals and the CHESS X-ray sources. Six superconducting wigglers were moved to a sector with zero-dispersion. The sector is densely populated with beam instrumentation and diagnostic devices. A new photon stop chamber will be used to handle the high synchrotron radiation power generated from the SCWs at high positron beam energy. A 12-m long gate-valve isolated straight sector was created in a second location, where many electron-cloud diagnostic chambers will be installed and tested. We also configured two very short sections in the arcs, with additional gate valves, to provide flexibility of exchanging various meter-long test chambers with minimum impact to the operations. Many retarding field analyzers were integrated into the vacuum modifications in SCWs, dipoles, and drifts to study EC growth and suppression techniques. Creating environments where both local and collaborator provided equipment can be easily installed has been a major objective in the modifications.

• G. Bregliozzi
  CERN, Geneva

In the CERN Large Hadron Collider, about 6 km of the UHV beam pipe are at ambient temperature and serve as experimental or utility insertions. The vacuum of these sectors rely on TiZrV non-evaporable getter (NEG) coating to achieve very low pressure. In the case of venting to atmosphere, the use of NEG coatings implies the bake-out of the vacuum sector to recover the low pressure and reactivate the NEG coatings. A new method to vent a vacuum sector to atmosphere allows performing short interventions without losing completely the performance of the already activated NEG coating. The principle is to over-pressurize the vacuum sector with neon gas which is not pumped by the NEG coatings, remove the faulty component and then pump down the sector again. The injection of such a gas in the vacuum sector aims at preserving the saturation of the NEG coatings during the exchange of the component. A detailed description of this new venting system will be presented and discussed. Preliminary results obtained from a laboratory venting system and its evaluation in the LHC tunnel to replace existing components will be presented.

• C. Garion, H. Kos
  CERN, Geneva

The Compact LInear Collider, under study, requires vacuum chambers with a very small aperture, of the order of 8 mm in diameter, and with a length up to around 2 m for the main beam quadrupoles. To keep the very tight geometrical tolerances on the quadrupoles, no bake out is allowed. The main issue is to reach UHV conditions (typically 10^-9 mbar static pressure) in a system where the vacuum performance is driven by water outgassing. For this application, a thin-walled stainless steel vacuum chamber with two ante chambers equipped with NEG strips, is proposed. The mechanical design, especially the stability analysis, is shown. The key technologies of the prototype fabrication are given. Vacuum tests have been carried out on the prototypes. The test set-up as well as the performance of the pumping system are presented and compared with predictions.

• E.N. Shaposhnikova, G. Arduini, J. Axensalva, E. Benedetto, S. Calatroni, P. Chiggiato, K. Cornelis, P. Costa Pinto, B. Henrist, J.M. Jimenez, E. Mahner, G. Rumolo, M. Taborelli, C. Yin Vallgren
  CERN, Geneva

Electron cloud build-up is a major limitation for the operation of the SPS with LHC beam above nominal intensity. These beams are envisaged in the frame of the LHC luminosity upgrade and will be available from the new injectors LPSPL and PS2. A series of studies have been conducted in order to identify possible means to suppress electron multipacting by coating the existing SPS vacuum chambers with thin films of amorphous carbon. After a description of the experimental apparatus installed in the SPS, the results of the tests performed with beam in 2008 will be presented.

• R. Veness
  CERN, Geneva

The LHC collider has recently started-up at CERN. It will provide colliding beams to four experiments installed in large underground caverns. A specially designed and constructed sector of the LHC beam vacuum system transports the beams though each of these collision regions, forming a primary interface between machine and experiment. ATLAS is the largest of the four LHC colliding beam experiments, being some 40 m long and 22 m in diameter. Physics performance, geometry and access imposed a large number of constraints on the design of the beam vacuum system. This paper describes the geometry and layout of the ATLAS beam vacuum system. Specific technologies developed for ATLAS, and for the alignment and installation of the vacuum chambers are described as well as the issues related to the physical interfaces with the experiment.

• R. Veness, S. Blanchard, P. Lepeule, D. Ramos, A. Rossi, G. Schneider
  CERN, Geneva

The LHC collider has recently completed commissioning at CERN. At four points around the 27 km ring, the beams are put into collision in the centre of the experiments ALICE, ATLAS, CMS and LHCb which are installed in large underground caverns. The ‘experimental vacuum systems’ which transport the beams through these caverns and collision points are a primary interface between machine and experiment and were developed and installed as one project at CERN. Each system has a different geometry and materials as required by the experiment. However, they all have common requirements from the machine, and use many common technologies developed for the project. In this paper we give an overview of the four systems stressing the similarities between them. We explain the technologies that were developed and applied for the installation, test, bakeout and subsequent closure of the experimental vacuum systems. We also discuss lessons learnt from the project.

• R. Kersevan, M. Hahn, I. Parat, D. Schmied
  ESRF, Grenoble

This paper outlines the present status and configuration of the ESRF vacuum system and its performance over the last years. A short overview of the installed vacuum devices is given as well as an outlook of future developments towards the planned ESRF upgrade. The storage ring down times caused by vacuum accidents have been dramatically improved due to a systematical survey using advanced vacuum diagnostic tools. Their use and drawbacks will also be discussed in this paper.

• M.C. Bellachioma, H. Kollmus, A. Krämer, J. Kurdal, H. Reich-Sprenger
  GSI, Darmstadt
• M. Bender
  LMU, München

Funding: EU design study, contract 515876, DIRAC-PHASE-1, RP6 SIS 18-2

For the future FAIR facility intensities up to 10¹² U²⁸⁺ ions per second are required. For this purpose the existing heavy ion synchrotron SIS18, which will serve as injector, has to be upgraded. Since the required base pressure is 10^-10 Pa, among the different measures undertaken to improve the existing UHV system, the installation of NEG coated magnet chambers is foreseen. Two magnetron sputtering facilities were designed and commissioned at GSI to perform the coating. The characterization of the thin films has been carried out by RBS and XPS. Considering that the vacuum chambers mounted in accelerators undergo several venting-activation cycles, a deep investigation on the NEG aging was performed by ERDA. Fourteen dipole and one quadrupole chambers were coated and installed in the SIS 18, and the replacement of the remaining magnet pipes will follow in the next years. Additionally to overcome the dynamic vacuum instability a collimation system equipped with thin film coated absorbers was successfully tested in 2008. The coating facilities, their operating mode, the results achieved on the thin film characterization, and the ones obtained in the SIS 18 are presented.

• K. Shibata, H. Hisamatsu, K. Kanazawa, M. Shirai, Y. Suetsugu
  KEK, Ibaraki

The titanium nitride (TiN) coating inside a beam duct has been recently attracting attention as a measure to mitigate the electron cloud effect in positron/proton rings. Here studied is the gas desorption from the TiN-coated copper beam duct, which will be adopted in the upgrade of KEK B-factory (KEKB). In the experiment, the pressure in a TiN-coated duct was measured and compared with that in a non-coated one. The TiN film (200 nm thick) was coated by DC magnetron sputtering at KEK. After an air exposure for the previously-determined period, the duct was evacuated by a turbo-molecular pump (300 l/s). At 50 hours after evacuation, the pressure was about 4 times larger than that for the case of the non-coated one. The residual gas was mainly water. In order to fine the minimum baking temperature to decrease the gas desorption from the TiN coating, the pressures were measured after the baking by changing the temperatures in the practical range, from 50 to 150 degrees. The pressure after the baking at 80 degrees was finally found to be comparable to that for the non-coated one. This paper describes these results in detail including the measurements of gas desorption rates.

• J. Kamiya, Y. Hikichi, K. Kanazawa, M. Kinsho, N. Ogiwara, Y. Takiyama
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

Since the start of the beam commissioning on October 2007, we have succeeded to increase the beam power of the Rapid Cycling Synchrotron (RCS) in the Japan Proton Accelerator Research Complex (J-PARC). The effect of the high power beam on the vacuum had become visible above the beam power of 50 kW. When the high power beam was operated at 25 Hz, the vacuum pressure became higher. Especially the vacuum of the injection area became worse than other areas. The residual gas analyzer was installed in order to investigate which kinds of outgassing were desorbed by the high power beam. The carbon compound mainly increased with the high power beam in the area. The source of the ougtassing is thought to be carbon foils for charge exchange and/or a electron catcher which was installed in order to collect the stripped electron by the carbon foil. After this, the RCS forwards into the stage where the high power beam is continuously operated during a few weeks. We will report the results of the conditioning effect on the vacuum by the beam itself.

• G.-Y. Hsiung, C.K. Chan, C.-C. Chang, C.L. Chen, S-N. Hsu, H.P. Hsueh, A. Sheng, C.Y. Yang, R. Yb
  NSRRC, Hsinchu
• J.-R. Chen
  National Tsing Hua University, Hsinchu

The Taiwan Photon Source (TPS) vacuum system has been designed for a 3 GeV electron storage ring of 24DBA lattice, 518.4 m circumference, 24 unit cells and 24 long straight sections of 6 in 12 m and 18 in 7 m. The vacuum ducts for each cell made from thick aluminum plates and extruded aluminum beam pipes will be precisely machined and welded for obtaining a low impedance with small quantity of flanges and bellows. The beam ducts in long straight sections will be flat extruded aluminum pipes of 10 mm vertical height inside which will be ready for installation of the undulators without breaking the vacuum. The BPMs, 2 in each straight sections and 5 in each cells, will be fixed on the ground or on the girder rigidly through the strong supports maintaining a displacement of < 0.1 micron against the stress force of 10 kg from the beam ducts. The small aperture of 10 mm inside the aluminum bending chamber rejects the PSD outgas from the crotch absorbers backfilled to the beam channel, while the surface of bending chamber will be cleaned with ozonated water to reach lower thermal outgassing rate that maintains a much lower averaged pressure below 100 nPa inside the beam ducts.

• C.Y. Yang, C.K. Chan, J.-R. Chen, G.-Y. Hsiung, C.K. Kuan, I.C. Sheng
  NSRRC, Hsinchu

Front End (FE) is the first area shapes radiation power to suit the need not only for protection but also for the beam line uses. About 14m long FE vacuum system will connect the ultra high vacuum (UHV) storage ring and beam line in Taiwan Photon Source (TPS). The Fixed mask (FM), photon absorber (PAB) and slit are the major high gas load components, especially in insertion Devices (ID) front ends, because of the synchrotron radiation. From the P(pressure)=Q(outgas)/S(pump) formula, there are some issues will be concerned to get lower vacuum pressure: The low outgassing rate of the vacuum chamber (Qthermal), the localization of the the pumps (IP and NEG) to pump down the outgassing of the photon simulated desorption(Qpsd), and the arrangement of the aperture and gas load . The basic pressure distribution of the bending magnet (BM) and ID front ends will be discussed.

• I. Sekachev, I.V. Bylinskii, A. Koveshnikov, I. Slobodov, D. Yosifov
  TRIUMF, Vancouver

The replacement of the 30-year-old Philips cryogenerator with a modern LINDE-1630 helium refrigerator is an important component of TRIUMF’s ongoing 500 MeV cyclotron refurbishing program. Two 10.7 m long cryopanels are cooled with liquid helium rather than with 17 K helium gas, as was the case with the cryogenerator. This has increased the pumping speed and, respectively, improved the vacuum in the approximately 100 m3 cyclotron tank. Additionally, the thermal shield, previously cooled with helium gas, is now cooled with liquid nitrogen. These changes have resulted in increased reliability of the cyclotron vacuum system and, consequently, longer operation periods without maintenance. The new refrigeration unit was commissioned in September 2007. The results from over one year of operational experience are discussed. Also, data on hydrogen cryopumping is presented.

• G.F. Pan, Z.G. Li, J.C. Qin, J.S. Xing, S.P. Zhang, T.J. Zhang
  CIAE, Beijing
• I. Sekachev
  TRIUMF, Vancouver

The design and cryo-test system of a plug-in cryopump used in CYCIAE-100 is introduced. The plug-in cryopump consists of two cryopanels, a baffle, a half-opened shield, and two GM refrigerators (CGR411, CVI) which power is 83W/80K at the first stage and 7.5W/20K at the second stage, its designed pumping speed is 15000L/s. Cryo-test system of plug-in cryopump employs the flux method to test pumping speed, cool-down time, ultimate pressure, temperature distribution on cryopanel and capacity at the pressure of 10-6Pa to 1Pa. The heat load calculation of cryopanel and shield including baffle is conducted in succession. In the end a comparison between design parameters and test results is drawn.

• Y. Wang, L. Fan, L. Liu, J. P. Wang, W. Wei, B. Zhang
  USTC/NSRL, Hefei, Anhui
• Y.F. Zhang
  IHEP Beijing, Beijing

TiN coating has been widely applied in surface treatments of particle accelerator vacuum chambers because of its characteristics such as good electrical conductivity, stability of performance, ability to block hydrogen permeation, low SEY, etc. With DC sputtering, TiN film has been coated on the inner face of a stainless steel pipe vacuum chamber, 86 mm in diameter and 2300 mm in length. The vacuum performances testing of the coated chamber has also been done, including thermal outgassing rate measurement, PSD measurement, and SEY measurement of samples. Compared with those of uncoated stainless steel chamber, the results show that coating TiN film is a very effective method of the treatment of particle accelerator vacuum chamber.

• Y. Wang, L. Fan, W. Li, J. P. Wang, W. Wei, B. Zhang
  USTC/NSRL, Hefei, Anhui
• Y.F. Zhang
  IHEP Beijing, Beijing

Titanium-Zirconium-Vanadium (TiZrV) nonevaporable getter (NEG), which can be fully activated after 4 hours heating at 200°;C, has been applied in many accelerators owing to the outstanding vacuum performance. In our experiments, TiZrV films have been deposited onto the inner face of stainless steel pipes via DC sputtering using argon gas as the sputtering gas. Samples have been investigated by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) to determine film composition and thickness, and by X-ray diffraction (XRD) to determine film structure and morphology. Second Electron Yields (SEY) of the TiZrV film have also been measured.

• P. Wise, M.H. Bates, D.C. Faircloth, S.R. Lawrie, A.P. Letchford, M. Perkins, M. Whitehead, T. Wood
  STFC/RAL/ISIS, Chilton, Didcot, Oxon
• C. Gabor
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• J.K. Pozimski, P. Savage
  Imperial College of Science and Technology, Department of Physics, London

The RAL Front End Test Stand (FETS) is being constructed to demonstrate a chopped H− beam of up to 60 mA at 3 MeV with 50 pps and sufficiently high beam quality for future high-power proton accelerators (HPPA). This paper details the mechanical engineering components manufactured so far and the challenges which need to be meet in the near future.

• H. Bluem, D. Holmes, T. Schultheiss
  AES, Medford, NY
• I. Ben-Zvi, A. Burrill, J. Kewisch, D. Pate, T. Rao, R.J. Todd, E. Wang, Q. Wu
  BNL, Upton, Long Island, New York

Funding: AES is funded under DOE SBIR contract #DE-FG02-06ER84450. BNL work is performed under DOE contract #DE-AC02-98CH10886.

The use of an RF electron gun with a magnetized cathode in place of a DC gun for ILC may reduce the requirements for emittance damping rings. Maintaining adequate lifetime of the necessary cathode material requires vacuum levels in the 10^-11 torr range. While vacuum levels around the 10^-9 torr range are common in a normal conducting RF gun, the cryogenic pumping of the cavity walls of a superconducting RF (SRF) gun may maintain vacuum in the range needed for GaAs cathode longevity. Advanced Energy Systems, Inc. is collaborating with Brookhaven National Laboratory to investigate the generation of polarized electron beams using a SRF photocathode gun. The team is developing an experiment to study the quantum lifetime of a GaAs cathode in a SRF cavity and investigate long term cavity performance while integrated with a cesiated GaAs cathode*. In addition to the experimental investigation, a design is being developed that is compatible with the production of high aspect ratio polarized electron beams. The mechanical and physics aspects of this design will be discussed.

*J. Kewisch, et. al., Presentation at PAC09.

• J. Kewisch, I. Ben-Zvi, A. Burrill, D. Pate, T. Rao, R.J. Todd, E. Wang, Q. Wu
  BNL, Upton, Long Island, New York
• H. Bluem, D. Holmes, T. Schultheiss
  AES, Medford, NY

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

Gallium arsenide cathodes are used in electron guns for the production of polarized electrons. In order to have a sufficient quantum efficiency lifetime of the cathode the vacuum in the gun must be 10^-11 torr or better, so that the cathode is not destroyed by ion back bombardment. All successful polarized guns are DC guns, because such vacuum levels can not be obtained in normal conducting RF guns. A superconductive RF gun may provide a sufficient vacuum level due to cryo-pumping of the cavity walls. We report on the progress of our experiment to test such a gun.

• D. Yu, Y. Luo
  DULY Research Inc., Rancho Palos Verdes, California

A Gallium Arsenide (GaAs) photocathode RF electron gun is useful if high polarization (>85%) and low emittance are required as, for example, in the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Accelerator Facility. DULY Research is developing a normal-conducting, L-band photoelectron gun in an ultra high vacuum accelerating structure called the Plane-Wave-Transformer (PWT) integrated with an activated, strained-lattice GaAs photocathode, as a continuous wave polarized electron source. We compare two designs (1-cell and ½ cell) of an L-Band PWT photoelectron gun in this paper. This RF gun will simplify the CEBAF photoinjector design by replacing the direct current (DC) gun, buncher cavities and the capture section. The new compact design provides a stiffer beam that is less subject to space charge blowup. In addition, a higher field gradient at the photocathode would mitigate electron and ion backbombardment problems. Cooling for a CW PWT gun is challenging but manageable.

• S. Lederer, S. Schreiber
  DESY, Hamburg
• P.M. Michelato, L. Monaco, C. Pagani, D. Sertore
  INFN/LASA, Segrate (MI)
• R. Ovsyannikov, M. Sperling, A. Vollmer
  BESSY GmbH, Berlin
• F. Stephan
  DESY Zeuthen, Zeuthen

Caesium telluride (Cs2Te) photocathodes are used as sources for electron beams because of their high quantum efficiency (QE) and their ability to release high peak current electron bunches in a high gradient RF-gun. A rapid unexpected decrease of the initial QE, from 10% to values below 0.5% in only a few weeks of operation, was observed. In XPS measurements we identify a peak of Fluorine possibly originating from Teflon. After identification and removal of this specific contaminant, the life time of the cathodes increased to several months. In addition we have investigated the response of fully functional photocathodes to extensive usage, bad vacuum conditions, and oxidation by means of XPS measurements. The experiments - carried out at the ISISS and the PM3 beam lines at the synchrotron facility BESSY – compare the chemical composition and electronic structure of freshly prepared, contaminated, used, and oxidised Cs2Te cathodes.

• S. Lederer, S. Schreiber
  DESY, Hamburg
• J.H. Han
  Diamond, Oxfordshire
• M. Hänel, F. Stephan
  DESY Zeuthen, Zeuthen
• P.M. Michelato, L. Monaco, C. Pagani, D. Sertore
  INFN/LASA, Segrate (MI)

Caesium telluride photocathodes are used as laser driven electron sources at FLASH and PITZ. FLASH is operated as user facility as well as for accelerator related studies and therefore has a constant and moderate usage of the cathodes. In contrary, PITZ is an injector R&D facility with a stronger usage of cathodes including gradients in the RF-gun of up to 60 MV/m. In the past, one concern of operating RF-guns with Cs2Te cathodes was the degradation of the quantum efficiency in a few weeks at FLASH and a couple of days at PITZ. Improved vacuum conditions and removing contaminants in both accelerators yielded an increased life time of several months. In this contribution we report on routinely performed QE measurements, investigations on the homogeneity of the electron emission, and dark current issues for both facilities.

• C. Shonaka, H. Higaki, K. Ito, D. Kubo, M. Kuriki, H. Okamoto
  HU/AdSM, Higashi-Hiroshima
• T. Konomi, T. Nakanishi, S. Okumi, M. Yamamoto
  Nagoya University, Nagoya

High brightness electron source is a key technology for future projects based on advanced accelerators. Although GaAs photo-cathode is very attractive because it can generate highly polarized and extremely high brightness electron beam, the limited operational life time is a technical issue. In Hiroshima University, a photo-cathode test bench is implemented for various studies of GaAs photo-cathode. Super high vacuum, 9E-9Pa, was achieved and the cathode was successfully activated by processes of heat cleaning technique and the alternate evaporation of Cs and oxygen. The quantum efficiency and its lifetime were investigated as a function of cathode temperature, simulating temperature rise by the high power cathode drive laser. Wavelength dependence was also investigated.

• R. Hajima
  JAEA/FEL, Ibaraki-ken
• Y. Honda, T. Miyajima, T. Muto, M. Yamamoto
  KEK, Ibaraki
• H. Iijima, R. Nagai, N. Nishimori
  JAEA/ERL, Ibaraki
• M. Kuriki
  HU/AdSM, Higashi-Hiroshima
• T. Nakanishi, S. Okumi
  Nagoya University, Nagoya

A 500-kV, 10-mA photocathode DC gun has been designed and is now under fabrication by the collaboration efforts of JAEA, KEK, Hiroshima Univ. and Nagoya Univ. The Cockcroft-Walton generator and the ceramic insulator are installed upright in the SF6 tank. We have adopted a multiple-stacked cylindrical ceramic insulator, because this type of ceramic insulator has shown good stability and robustness at the 200-kV Nagoya polarized gun and the 250-kV JAEA FEL gun. All the vacuum chambers are made of titanium alloy with very low out-gassing. The Cockcroft-Walton generator, the ceramic insulator, the vacuum chambers will be fabricated by April 2009 and a high-voltage test will be started soon later. Up-to-date status of the gun development will be presented in detail.

• R.R. Mitchell, B.A. Gardner, T. Ilg
  LANL, Los Alamos, New Mexico
• M. Leitner
  LBNL, Berkeley, California
• B.A. Prichard
  SAIC, Los Alamos, New Mexico

Funding: National Nuclear Security Administration of the US Department of Energy

The Dual-Axis Radiographic Hydrodynamic Test Facility (DARHT) at Los Alamos National Laboratory (LANL) consists of two linear induction accelerators oriented at right angles to each other. The DARHT First Axis has been successfully operated since 1999 and produces a 60 ns pulse with beam energy of 20 MeV and beam current of 1.9 kA. The DARHT Second Axis was successfully commissioned in May 2008 and produces a 1600 ns pulse with beam energy of 17.5 MeV and beam current of 2.1 kA. The Second Axis Injector uses a 16.5 cm diameter thermionic cathode with a 10 A/cm² required current density to emit electrons into the accelerator. During the early Second Axis commissioning activities in 2006, deficiencies in the DARHT Second Axis Injector were found that prevented the injector cathode from meeting the required 10 A/cm² current density. A comprehensive campaign was initiated to solve the injector cathode performance issues. This paper describes the deficiencies found and the solutions used to enable the DARHT Second Axis Injector to meet its requirements.

• M.L. Neubauer, K.B. Beard, R. Sah
  Muons, Inc, Batavia
• C. Hernandez-Garcia, G. Neil
  JLAB, Newport News, Virginia

Funding: Supported in part by USDOE Contract No. DE-AC05-84-ER-40150.

Many user facilities such as synchrotron light sources and free electron lasers require accelerating structures that support electric fields of 10-100 MV/m, especially at the start of the accelerator chain where ceramic insulators are used for very high gradient DC guns. These insulators are difficult to manufacture, require long commissioning times, and have poor reliability, in part because energetic electrons bury themselves in the ceramic, creating a buildup of charge and causing eventual puncture. A novel ceramic manufacturing process is proposed. It will incorporate bulk resistivity in the region where it is needed to bleed off accumulated charge caused by highly energetic electrons. This process will be optimized to provide an appropriate gradient in bulk resistivity from the vacuum side to the air side of the HV standoff ceramic cylinder. A computer model will be used to determine the optimum cylinder dimensions and required resistivity gradient for an example RF gun application. A ceramic material example with resistivity gradient appropriate for use as a DC gun insulator will be fabricated by glazing using doping compounds and tested.

• E.J. Montgomery, D.W. Feldman, P.G. O'Shea, P.Z. Pan
  UMD, College Park, Maryland
• K. L. Jensen
  NRL, Washington, DC
• N.A. Moody
  LANL, Los Alamos, New Mexico

Funding: This project is funded by the Joint Technology Office and the Office of Naval Research.

High performance FELs require photocathodes with quantum efficiencies of several percent at green wavelengths, kHr lifetime, kA/cm² peak and A/cm² average current, and ps response. Such cathodes are challenged to maintain requisite high quantum efficiency while in harsh accelerator vacuum conditions. Delicate surface coatings are often cesium-based, and therefore are reactive with contaminant gases. The dispenser photocathode architecture resupplies the cesium coating from a subsurface reservoir through a porous substrate, thereby extending lifetime*. Recesiation has been shown to rejuvenate Cs:Ag cathodes from O2, CO2, and N2O contamination**, and theory of dispenser photocathodes is advancing***. We here investigate the fabrication, contamination, and external recesiation of alkali antimonides with high quantum efficiency, in support of the dispenser photocathode design.

*Moody et al., APL90, 114108.
**Montgomery et al., Proc. AACW 2008 (submitted for publication).
***K. Jensen et al., (this conference).

• K. Miyoshi, Y. Muroya, A. Sakumi, T. Ueda, M. Uesaka
  The University of Tokyo, Nuclear Professional School, Ibaraki-ken
• K. Kambe
  UTNL, Ibaraki

Multi-Alkali photocathode has the good possibility as a electron source which has high quantum efficiency and low workfunction. However the surface of the cathode is sensitive over the electric field of 100[MV/m] in a RFgun, the amount of dark current is not negligible. In order to reduce such a dark current, we consider the valance of the electric field between half-cell and full-cell of BNL-IV RF gun by numerical simulation using GPT code. In this work we will show that high quality electron beam can be transported on the condition that appled electric field in half and full cell is about 50[MV/m] and 150[MV/m] respectively.

• L. Rossi, V. Parma
  CERN, Geneva

The LHC magnet system has been largely commissioned in 2007-08: all sectors up to 7 kA (4 TeV proton beam energy); six (out of eight) sectors were commissioned up 9.3 kA (5.5 TeV) and one to 11.5 kA (6.9 TeV). For more than one week, both beams have been injected, circulated and captured in the RF bucket, thus assessing the optics at injection energy. The incident in sector 3-4, originated by a serious defect of a high-current joint between magnets with large collateral damage, has changed the plans: magnets in the damaged zone (about 50) are being substituted or repaired meanwhile a campaign of consolidation is under way. During commissioning, the training of the main dipoles was longer than expected on the basis of reception tests of individual magnets , thus pointing to a partial loss of quench memory. The thermal performance is within heat losses estimates and the spectacular easiness of the first injection test on 10th September has demonstrated the very good field quality, precise understanding of magnetic characteristics, quality of the elaborate field modeling and the very good shape of the magnets with proper alignment of the machine.

Slides

• O. Singh, R. Alforque, B. Bacha, A. Blednykh, P. Cameron, W.X. Cheng, L.R. Dalesio, A.J. Della Penna, L. Doom, R.P. Fliller, G. Ganetis, R. Heese, H.-C. Hseuh, E.D. Johnson, B.N. Kosciuk, S.L. Kramer, S. Krinsky, J. Mead, S. Ozaki, D. Padrazo, I. Pinayev, V. Ravindranath, J. Rose, T.V. Shaftan, S. Sharma, J. Skaritka, T. Tanabe, Y. Tian, F.J. Willeke, L.-H. Yu
  BNL, Upton, Long Island, New York

A new 3rd generation light source (NSLS-II project) is in the early stage of construction at Brookhaven National Laboratory. The NSLS-II facility will provide ultra high brightness and flux with exceptional beam stability. It presents several challenges in the diagnostics and instrumentation, related to the extremely small emittance. In this paper, we present an overview of all planned instrumentation systems, results from research & development activities; and then focus on other challenging aspects.

Slides

• R.W. Assmann
  CERN, Geneva

A first stage collimation system has been installed for the 2008 first beam commissioning of the LHC. It consists of 88 collimators distributed around the ring and the two injection lines. Each collimator has two jaws for which positions and angles must be controlled and monitored with high precision. The LHC collimation system was put into operation from July to October 2008. The installed system is described and the first results from system operation without and with beam are presented. In particular, it is shown that the LHC collimation system achieved the specified accuracy and reproducibility of jaw positioning. The next steps in collimation commissioning and the expected system evolution are described. Planned system upgrades for high LHC beam intensities are outlined.

Slides

• S.J. Pasky, A.R. Cours, A.E. Grelick, A.F. Pietryla, N. Sereno, T.L. Smith, W.D. Wright
  ANL, Argonne

Funding: Work supported by U.S.Department of Energy, Office of Science, Office of Basic Energy Science, under Contract No. DE-AC02-06CH 11357

Recently, a new SLED test stand located in the Advanced Phone Source linac klystron gallery was developed using a spare modulator-klystron system and a recently developed prototype water station. The new test stand will be used to condition, tune and perform rf measurements on spare SLEDs without interfering with normal daily linac operations. This will allow technical groups to replace a low-performance SLED from one of the operational linac sectors with a fully conditioned SLED. The pre-conditioned SLED is expected to require less conditioning time after being put into operation compared to an unconditioned SLED. As an additional benefit, the prototype water station system developed to replace aging linac water systems can be tested under realistic conditions. In this paper, we describe the test stand design, prototype water station system, and first results using it to condition SLEDs and perform SLED rf measurements.

• M.L. Langlois, M. Cornelis, D. Einfeld, F. Peréz
  CELLS-ALBA Synchrotron, Cerdanyola del Vallès

The Dampy cavity, operating at 500 MHz and up to 160 kW, normal conducting HOM damped, will be used in the ALBA storage ring. The pre-series has shown two problems. First, the HOM damping is very efficient but for one mode. The longitudinal impedance of the E011 mode was found to be around 11 kΩ, slightly above ALBA stability threshold. Second, overheating close to the dampers flanges induces a vacuum leak after several thermal cyclings. The maximum achieved operational dissipated power is 40 kW, if power is further increased a leak opens at one of the dampers flanges. In order to alleviate this latter drawback, two modifications have been implemented in two different cavities. The pre-series has been provided with short-circuits bridging waveguide ridges and cavity body. These are supposed to decrease the current in the area of the flanges. The first production cavity features a reduced thermal impedance between the water cooling channels and the area of overheating by replacing stainless steel by copper in the critical area. Both these cavities are currently under test and this paper will show the results.

• A. Kanareykin, P. Schoessow
  Euclid TechLabs, LLC, Solon, Ohio
• S. Kazakov
  KEK, Ibaraki
• E. Nenasheva
  Ceramics Ltd., St. Petersburg
• V.P. Yakovlev
  Fermilab, Batavia

Funding: This work was supported by the US Department of Energy

Euclid TechLabs LLC is developing BST based ferroelectric elements designed to be used as the basis for new advanced accelerator components operating in the 1.3 GHz frequency range and intended for Project X and ILC applications. These new ferroelectric elements are designed for the fast active tuner for SC cavities that can operate in air at low biasing DC fields in the range of 15 kV/cm. The BST(M) material (BST ferroelectric with Mg-based additives) allows fast switching and tuning in vacuum and in air both; switching time of material samples < 10 ns has been demonstrated. The overall goal of the program was to design an L-band externally-controlled fast ferroelectric tuner for controlling the coupling of superconducting RF cavities for the future linear colliders. The tuner prototype has been built; a time response of <30 ns, or 1 deg. in 0.5 ns has been reached. . The following problems are addressed: (i) lowering the losses in the ferroelectric material; (ii) improving the technique of the ferroelectric element metallization and brazing; and (iii) improvement breakdown threshold at high voltage bias.

• P. Schoessow, C.-J. Jing, A. Kanareykin
  Euclid TechLabs, LLC, Solon, Ohio
• W. Gai, J.G. Power
  ANL, Argonne
• O.V. Sinitsyn
  UMD, College Park, Maryland

Funding: Work supported by the US Department of Energy.

The development of high gradient rf driven dielectric accelerating structures is in part limited by the problem of multipactor. The first high power experiments with an 11.424-GHz rf driven alumina accelerating structure exhibited single surface multipactor. Unlike the well understood multipactor problem for dielectric rf windows, where the rf electric field is tangential and the rf power flow is normal to the dielectric surface, strong normal and tangential rf electric fields are present from the TM01 accelerating mode in the DLA and the power flow is parallel to the surface at the dielectric-beam channel boundary. While a number of approaches have been developed, no one technology for MP mitigation is able to completely solve the problem. In this paper we report on numerical calculations of the evolution of the MP discharge, and give particular attention to MP dependence on the rf power ramp profile and the use of engineered surface features on the beam channel wall to interrupt the evolution of the multipactor discharge.

• F. Caspers, E. Montesinos
  CERN, Geneva
• S. Anza, J. Gil, C. Vicente
  aurorasat, Paterna
• V.E. Boria
  DCOM-iTEAM-UPV, Valencia
• W. Bruns
  WBFB, Berlin
• L. Conde
  Universidad Politecnica de Madrid, ETSI Aeronauticos, Madrid
• L. Galan
  UAM, Madrid
• B. Gimeno
  UVEG, Burjasot (Valencia)
• C. Miquel Espanya, D. Raboso
  ESA-ESTEC, Noordwijk
• I. Montero
  CSIC, Madrid

Multipactor phenomena which are closely linked to the SEY (secondary electron yield) can be mitigated by many different methods including groves in the metal surface as well as using electric or magnetic bias fields. However frequently the application of global magnetic or electric bias field is not practicable considering the weight and power limitations on-board satellites. Additionally, surface grooves may degrade the RF performance. Here we present a novel technique which is based on a magnetostatic field pattern on the metallic surface with fast spatial modulation in the order of 30 micron. This field pattern is produced by proper magnetization of an underlying ferromagnetic layer such as nickel. Simulations and preliminary experimental results will be shown and a number of applications, both for particle accelerators and satellite microwave payloads are discussed.

• Y.I. Levinsen, S. Calatroni, A. Descoeudres, M. Taborelli, W. Wuensch
  CERN, Geneva

The understanding of electrical breakdowns has a critical role in the design of the RF accelerating cavities for the CLIC linear collider. In this context a new statistical model of the conditioning process and breakdown rate evolution is presented for a DC spark system with tip-plane electrode geometry charged from a capacitance. The approach requires a small amount of assumptions, but can still make several interesting predictions. Electrode gap distance dependence on the saturated breakdown field and spitfest (grouped breakdowns) are among the phenomena that could be explained from this simple model.

• Y.I. Levinsen, S. Calatroni, A. Descoeudres, M. Taborelli, W. Wuensch
  CERN, Geneva

Electrical breakdown in the accelerating cavities set a potential limit to the performance of the CLIC linear collider. Vacuum degradation and beam instability are possible outcomes from a breakdown if too much gas is released from the cavity surface. Quantitative data of gas release are provided for copper electrodes (milled Cu-OFE, as-received and heat-treated), and molybdenum electrodes. These data are produced from a controlled DC spark environment with capacitance charged anode at fixed energy.

• M. Popovic, A. Moretti
  Fermilab, Batavia
• C.M. Ankenbrandt, M.A.C. Cummings, R.P. Johnson, M.L. Neubauer
  Muons, Inc, Batavia

Funding: Supported in part by FRA DOE contract number DE-AC02-07CH11359

RF cavities below 800 MHz are large, so alternative cavities at low frequencies are needed. Novel dielectric loaded RF cavities will allow smaller diameter cavities to be designed; changing the frequency of a cavity design would be as simple as changing the dielectric cylinder insert material or inner radius of the dielectric in the cavity. This paper discusses RF cavities loaded with dielectric material that could be used in various ways for muon facilities. The examples given are for 400 and 800 MHz cavities. Our initial motivation was to use dielectric to reduce the radial size of gas-filled cavities in helical cooling channels, but dielectric-loading has potential use in vacuum cavities for suppression of dark current emission. We also studied cavities that can be used for the phase rotation channel in the front end of a muon collider or neutrino factory.

• K. Yokoyama, S. Fukuda, Y. Higashi, T. Higo, N. Kudoh, S. Matsumoto, Y. Watanabe
  KEK, Ibaraki

High-gradient RF breakdown studies have been in progress at Nextef (New X-band Test Facility at KEK) since 2006. To study the characteristics of different materials on high-field RF breakdown, we have performed high-gradient experiments by using narrow waveguides that has a field of around 140 MV/m at 50 MW power. Breakdown rates of stainless-steel and copper cases were measured and the results are described in this paper.

• L. Cao, M. Fan, T. Hu, J. Huang, D. Li
  HUST, Wuhan

Funding: Nation Nature Science Foundation of China,10435030

At Huazhong University of Science and Technology (HUST), the design study of a 10 MeV compact cyclotron CYCHU-10 for the application of Positron Emission Tomography (PET) has been developed since 2007. This paper describes the recent status of RF cavities including numerical calculation results of basic parameters, the capacitive trimmer to overcome frequency shift when in operation and the construction and cold test of the 1:1 scale prototype. The inductive coupling loop design and matching simulation with the RF power generator are also presented

• A. Burrill, I. Ben-Zvi, R. Calaga, T. D'Ottavio, L.R. Dalesio, D.M. Gassner, H. Hahn, L.T. Hoff, A. Kayran, J. Kewisch, R.F. Lambiase, D.L. Lederle, V. Litvinenko, G.J. Mahler, G.T. McIntyre, B. Oerter, C. Pai, D. Pate, D. Phillips, E. Pozdeyev, C. Schultheiss, L. Smart, K. Smith, T.N. Tallerico, J.E. Tuozzolo, D. Weiss, A. Zaltsman
  BNL, Upton, Long Island, New York

This paper will present the preliminary results of the testing of the 703 MHz SRF cryomodule designed for use in the ampere class ERL under construction at Brookhaven National Laboratory. The preliminary VTA cavity testing, carried out at Jefferson Laboratory, demonstrated cavity performance of 20 MV/m with a Qo of 1x10¹⁰, results we expect to reproduce in the horizontal configuration. This test of the entire string assembly will allow us to evaluate all of the additional cryomodule components not previously tested in the VTA and will prepare us for our next milestone test which will be delivery of electrons from our injector through the cryomodule to the beam dump. This will also be the first demonstration of an accelerating cavity designed for use in an ampere class ERL, a key development which holds great promise for future machines.

• N. Solyak, T.J. Peterson, V. Poloubotko, V.P. Yakovlev
  Fermilab, Batavia
• O. Brunner, E. Ciapala, T.P.R. Linnecar, J. Tuckmantel, W. Weingarten
  CERN, Geneva
• R. Calaga
  BNL, Upton, Long Island, New York

Funding: This work has been partially performed under the auspices of the US department of energy

The complex LHC crab cavity design and the beam-line configuration pose very tight constraints for the cryostat design. An initial assessment of the LHC main RF cryostat points to a new design both from the RF and engineering point of view. The cavity and tunnel constraints are discussed in detail and an intial cryostat design along with the cryogenic circuit is presented.

• J.K. Sekutowicz
  DESY, Hamburg
• P. Kneisel
  JLAB, Newport News, Virginia

A coaxial coupling device located in the beam pipe of the TESLA type superconducting cavities provides for better propagation of Higher Order Modes (HOMs) and their strong damping in appropriate HOM couplers. Additionally, it also provides efficient coupling for fundamental mode RF power into the superconducting cavity. The whole coupling device can be designed as a detachable system. If appropriately dimensioned, the magnetic field can be minimized to a negligible level at the flange position. This scheme, presented previously*, provides for several advantages: strong HOM damping, flangeable solution, exchangeability of the HOM damping device on a cavity, less complexity of the superconducting cavity, possible cost advantages. This contribution will describe the results of the first cryogenic test.

*J. Sekutowicz et al., Proceedings LINAC08, Victoria, Canada, 2008.

• H.T. Edwards, T.T. Arkan, M.H. Foley, M. Ge, E.R. Harms, A. Hocker, T.N. Khabiboulline, M.W. McGee, D.V. Mitchell, D.R. Olis, A.M. Rowe, N. Solyak
  Fermilab, Batavia

Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-07CH11359.

Fermilab is in a collaboration with DESY to provide a cryomodule containing 4-3.9 GHz superconducting RF cavities to be placed in TTF/FLASH. The purpose of this 'Third Harmonic' module is to linearize the nonlinear beam energy-time profile produced by the 1.3 GHz accelerating gradient. The completed module has now been shipped to DESY and is awaiting cold, powered testing and installation into FLASH later this year. We report on experience with fabricating, testing, assembling, and shipping the module and its components with a focus on cavity test results.

• M.W. McGee, J.T. Volk
  Fermilab, Batavia

Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02- 07CH11359 with the U.S. Department of Energy.

Recently developed, the Superconducting Radio Frequency (SRF) Accelerator Test Facilities at Fermilab supports the International Linear Collider (ILC), High Intensity Neutrino Source (HINS), a new high intensity injector (Project X) and other future machines. These facilities; Meson Detector Building and New Muon Lab (NML) have very different foundations, structures, relative elevations with respect to grade level and surrounding soil composition. Also, there are differences in the operating equipment and their proximity to the primary machine. All the future machines have stringent operational stability requirements. The present study examines both near-field and ambient vibration in order to develop an understanding of the potential contribution of near-field sources (e.g. compressors, ultra-high and standard vacuum equipment, klystrons, modulators, utility fans and pumps) and distant noise sources to the overall system displacements. Facility vibration measurement results and methods of possible isolation from noise sources are presented and discussed.

• L. Ristori, G. Apollinari, I.G. Gonin, T.N. Khabiboulline, A. Mukherjee, J.P. Ozelis, D.A. Sergatskov, R.L. Wagner, R.C. Webber
  Fermilab, Batavia

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359

The Fermilab High Intensity Neutrino Source (HINS) Linac R&D program is building a 60 MeV superconducting H^- linac. The Linac incorporates SC solenoids, high power RF vector modulators and SC spoke-type accelerating cavities starting at 10 MeV. This will be the first application and demonstration of any of these technologies in a low-energy, high-intensity proton/H^- linac. The HINS effort is relevant to a high intensity, SC H^- linac that might serve the next generation of neutrino physics and muon storage ring/collider experiments. Three types of superconducting resonators are used in the linac front end. Single Spoke Resonators typs^-1 (SSR1) at Beta=0.2, Single Spoke Resonators type-2 (SSR2) at Beta=0.4 and Triple Spoke Resonators (TSR) at Beta=0.6. In this paper we describe the Buffer Chemical Polishing (BCP) performed on SSR1-#2 and the results of the cold tests for this bare cavity. We also describe the inelastic tune performed on cavity SSR1-#1, during this operation we measured also the spring constant and the frequency sensitivity of the end walls. We have also completed the design for the helium vessel that will be used to jacket SSR1 resonators and we present its design here.

• E.N. Zaplatin, R. Maier, M. Pap, R. Stassen, R. Tölle
  FZJ, Jülich
• W. Behr, H. Glueckler, W. Guenther, J. Wolters
  Forschungszentrum Jülich GmbH, Institut fur Nuklearchemie (INC), Jülich

The paper describes the design, fabrication and first test results of the triple-spoke cavity (resonant frequency 352 MHz, beta=0.48) developed at Forschungszentrum Jülich in the frame of High Intensity Pulsed Proton Injector project. The cavity has 5 cm diameter beam aperture, a transverse radius of 21.7 cm and the whole length of 78 cm. An initial wall thickness of niobium sheets used for cavity fabrication was around 4 mm. The RF cavity design has been adapted to two main goals - the simplest technology of cavity manufacture and for the prime goal of the project to achieve the best possible structural parameters (Lorenz force frequency shift and a resonant frequency pressure dependence). Intense cavity structural analyses have been conducted and the further prospectives on cavity developments are also presented. Construction of the niobium cavity prototype has been completed, the cavity has been chemically processed. Results of initial cold test are discussed.

• D. Horan, D.J. Bromberek, L.H. Morrison, G.J. Waldschmidt
  ANL, Argonne

Funding: U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357

Work is underway to improve the reilability and power handling capability of input couplers used in the Advanced Photon Source single-cell and five-cell cavities. Coupler performance during conditioning in a test cavity suggests that ceramic material defects and field enhancement caused by a mechanical gap in the coupler design may be responsible for past coupler failures at high power. Simulation results and high-power test data will be discussed.

• T. Sakurai, T. Inagaki, C. Kondo, T. Shintake, K. Shirasawa
  RIKEN/SPring-8, Hyogo
• S. Suzuki
  JASRI/SPring-8, Hyogo-ken

We report the high power rf test results of C-band accelerator system for X-ray free electron laser (XFEL) in SPring-8. The C-band accelerator system is composed of two C-band accelerator of Choke-mode-type HOM damping structure, the rf pulse compressor, the 50 MW klystron, oil-filled modulator and solid state switching high voltage charger. It is designed to operate at rather high accelerating gradient as high as 35 MV/m, therefore it is crucial to evaluate high gradient performance and reject some component with defect or poor performance. In the 8 GeV main accelerator, 64 C-band systems will be used in total, whose components are under mass production at several industries in Japan. Some of these systems have been installed and tested in high-power test bunker since July 2008. We report on statistics of the high voltage breakdown, and related measurement; such as power calibration of klystron 50 MW, gain measurement on rf pulse compressor.

• D. Einfeld
  CELLS-ALBA Synchrotron, Cerdanyola del Vallès

ALBA is the first 3rd generation synchrotron light source to be build in Spain. The project is in the process of installation, with the LINAC already commissioned, and the Booster and Storage Ring in the installation phase, and the building already completed. The Booster synchrotron is expected to be finish and commission by the end of summer 2009, and the storage ring commissioning should take place in spring 2010. Most of the major components are already delivered and tested in-house, among those the vacuum system, the magnets, the RF cavities, etc. In this paper, the status of the project and of the most relevant components is reviewed.

• M. Sachwitz, A. Donat, U. Gensch, R. Heller, R. Sternberger, D. Thürmann, L.V. Vu
  DESY Zeuthen, Zeuthen
• U. Hahn, S. Karstensen, H. Schulte-Schrepping, K.I. Tiedtke
  DESY, Hamburg

A first prototype of a switching mirror has been designed, built and tested. With a repetition rate of up to 2.5 Hz the mirror is used to provide different beam lines with the Laser light produced by FLASH. The repetition accuracy is in the order of 1 um whereas the yawing is about 1 arcsec.

• G. Agarwal, R. Dhunna, I.P. Jain, V.K. Kulshrestha
  UOR, Jaipur
• D. Kabiraj
  IUAC, New Delhi

Swift Heavy Ion (SHI) induced modification at Metal/Si interfaces has emerged as an interesting field of research due to its large applications. In the present study we investigate SHI induced mixed molybdenum silicide film with ion fluences. The Molybdenum and Si thin thin films were deposited on Silicon substrates using e-beam evaporation at 10^-8 torr vacuum. Thin films were irradiated with Au ions of energy 120 MeV to form molybdenum silicide. The samples were characterized by grazing incidence X-ray diffraction (GIXRD) technique for the identification of phase formation at the interface. Rutherford backscattering spectrometry (RBS) was used to investigate the elemental distribution in the films. The mixing rate calculations were made and the diffusivity values obtained leads to a transient melt phase formation at the interface according to thermal spike model.

• W. Liu, Y.-C. Du, W.-H. Huang, C.-X. Tang, D. Wu
  TUB, Beijing

The preliminary experiments and three-dimensional (3D) particle-in-cell (PIC) simulations of terahertz (THz) coherent transition radiation (CTR) performed at the Accelerator Laboratory of Tsinghua University are reported in this paper. THz radiation is generated from the interactions of Titanium foil with the ultrashort electron beam produced by the photocathode RF gun. The frequency and power of radiation are measured with the Martin-Pupllet interferometer and Gollay Cell detector, respectively. The radiation characteristics depending on the foil properties are preliminarily studied with the experiments and PIC simulations. On the other hand, the distribution of radiation field pattern and energy are studied by numerical calculated, and those results are in agreement with the PIC simulations.

• M.A. Ferderer, D. Churanov, A.A. Krasnov, M. Urbant, A.A. Zavadtsev, D.A. Zavadtsev
  IBS, Atlanta, Georgia
• S.V. Kutsaev, N.P. Sobenin
  MEPhI, Moscow

In today’s turbulent and unsecure world, an X-ray radiographic image and a dual-energy Z-detection mapping of a container contents are needed to provide a reasonable level of port and border security. An interlaced dual-energy electron-beam linac has been developed for the use in cargo inspection systems to meet this growing need. Electron energy of the linac is software controllable from 3 to 15 MeV. Nominal operating energy levels of 4 and 9 MeV were chosen. The 9 MeV beam energy operating point is used for generating the X-ray radiographic image while 4 and 9 MeV beams are used for Z-detection mapping. The S-band linac has been calculated, designed, built and tested. Frequency repetition rate of alternating 4 and 9 MeV beams is 240 Hz. Pulse length is 10 μs. The beam energy in each beam pulse is over 10 J.

• A. Bungau, R. Cywinski
  University of Huddersfield, Huddersfield
• J.S. Lord
  STFC/RAL, Chilton, Didcot, Oxon

The pulsed muon channel of the ISIS facility at Rutherford Appleton Laboratory has been successfully commissioned and operated for many years as a tool for MuSR studies in condensed matter research. At the present time, the graphite target, of dimensions 50*50*7 mm oriented at 45 degrees to a proton beam of 800 MeV energy, gives 16000 surface muons per double proton pulse passing through the entrance aperture of the aluminium window which separates the muon beamlines from the main proton beam. Potential improvements to the target geometry, and optimisation of the design and estimated performance of the muon target are presented in this paper.

• D. Guilhem, J.-L. Lemaire
  CEA, Arpajon

A 15 MeV accelerator scheme based on a DC photo-injector and a RF superconducting linac has been proposed as a new facility for radiography applications. The design of a 15 MeV, 2 kA peak current, electron accelerator for the DEINOS project is presented The beam operating condition is a limited number of bunches up to twenty electron micro-pulses of 100 ps time duration and 200 nC bunch charge emitted at 352 MHz repetition rate from a Cs2Te photocathode and accelerated to 2.5 MeV in the DC diode before injection into a superconducting linac. A general description of the main accelerator components and the beam dynamics simulations are presented. The overall beam dynamics simulation process based on LANL POISSON-SUPERFISH and PARMELA codes and the results will be reviewed.

• S.S. Gilardoni, D. Allard, M.J. Barnes, O.E. Berrig, A. Beuret, D. Bodart, P. Bourquin, R. Brown, M. Caccioppoli, F. Caspers, J.-M. Cravero, C.G.A. Dehavay, T. Dobers, M. Dupont, G. Favre, T. Fowler, F. Franchi, M. Giovannozzi, J. Hansen, M. Karppinen, C. Lacroix, E. Mahner, V. Mertens, J. Monteiro, R. Noulibos, E. Page, R. Principe, C. Rossi, L. Sermeus, R.R. Steerenberg, G. Vandoni, G. Villiger, Th. Zickler, C. de Almeida Martins
  CERN, Geneva

The implementation of new Multi-turn extraction at the CERN Proton Synchrotron required major hardware changes for the nearly 50-year old accelerator. The installation of new PFNs and refurbished kicker magnets for the extraction, new sextupole and octupole magnets, new power converters, together with an in-depth review of the machine aperture leading to the design of new vacuum chambers was required. As a result, a heavy programme of interventions had to be scheduled during the winter shut-down 2007-8. The newly installed hardware and its commissioning is presented and discussed in details.

• J.A. Uythoven, W. Bartmann, J. Borburgh, T. Fowler, B. Goddard, M. Meddahi
  CERN, Geneva

The conceptual considerations of a fast injection system for protons and ions in the proposed PS2 accelerator are presented. Initial design parameters of the injection septum and kicker systems are derived, taking into account rise and fall times, apertures and machine optics. The requirements for an injection dump used for failures are described. Possible limitations and technical issues are outlined.

• F. Broggi
  INFN/LASA, Segrate (MI)
• A. Bacci, A.R. Rossi, L. Serafini
  Istituto Nazionale di Fisica Nucleare, Milano
• A. Cianchi
  INFN-Roma II, Roma
• A. Clozza, G. Di Pirro
  INFN/LNF, Frascati (Roma)

High vacuum has always been mandatory in particle accelerator. This is true especially for circular machine, where the beam make thousands or millions turns, and beam lifetime is heavily affected by the residual gas scattering. In dimensioning the interaction chamber for a plasma accelerator experiment, because of gas needed and the diagnostics and control devices foreseen, the problem of the effect of the residual gas on the beam arose. Simulation of the beam interaction with the residual gas in the chamber has been performed with FLUKA code. The effects of different vacuum levels on the electron beam is reported and consequences on the beam quality in linacs is discussed.

• V.V. Danilov, Y. Liu
  ORNL, Oak Ridge, Tennessee
• K.B. Beard, V.G. Dudnikov, R.P. Johnson
  Muons, Inc, Batavia
• M.D. Shinn
  JLAB, Newport News, Virginia

Funding: Supported in part by USDOE Contract No. DE-AC05-84-ER-40150. Supported in part by USDOE Contract DE-AC05-00OR22725

The ORNL spallation neutron source (SNS) user facility requires a reliable, intense beams of protons. The technique of H^- charge exchange injection into a storage ring or synchrotron has the potential to provide the needed beam currents, but it will be limited by intrinsic limitations of carbon and diamond stripping foils. A laser in combination with magnetic stripping has been used to demonstrate a new technique for high intensity proton injection, but several problems need to be solved before a practical system can be realized. Technology developed for use in Free Electron Lasers is being used to address the remaining challenges to practical implementation of laser controlled H^- charge exchange injection for the SNS. These technical challenges include (1) operation in vacuum, (2) the control of the UV laser beam to synchronize with the H^- beam and to shape the proton beam, (3) the control and stabilization of the Fabry-Perot resonator, and (4) protection of the mirrors from radiation.

• C.K. Chan, C.-H. Chang, P.J. Chou, C.-S. Fann, G.-Y. Hsiung, Y.-H. Liu, C.-S. Yang
  NSRRC, Hsinchu
• J.-R. Chen
  National Tsing Hua University, Hsinchu

The Taiwan Photon Source (TPS) is a new 3 GeV synchrotron light source to be built at the National Synchrotron Radiation Research Center (NSRRC) in Taiwan. The design of TPS is aimed to provide a low-emittance and high-brilliance beam with operation in the top-up mode. In this paper we present the design of the TPS injection section and the transport line from booster to storage ring. The specifications and parameters of the septa, kickers, and ceramic chambers are also described.

• J.A. Safranek, W.J. Corbett, X. Huang, J.J. Sebek
  SLAC, Menlo Park, California
• W.X. Cheng
  BNL, Upton, Long Island, New York

Funding: Work supported by the US Department of Energy, Office of Basic Energy Sciences.

In the past, SPEAR3 has had typically 50 to 70% injection efficiency. Much of the lost injected beam hit the small gap vacuum chambers at the insertion devices. We are now implementing injection with photon beamline shutters open, so these losses create Bremsstrahlung down the photon beamlines, increasing radiation levels on the photon experimental floor. In this paper, we describe work done to better control the booster to SPEAR (BTS) transport line beam so as to reduce losses during injection. We have used new BTS BPM electronics to control the transport line trajectory. The trajectory response on these BPMs has been used to correct the BTS optics. We use turn-by-turn BPM readings of the injected beam in SPEAR to optimize the BTS trajectory in all six transverse and longitudinal coordinates. We use turn-by-turn profile measurements of the injected beam to verify the BTS optics correction. The stainless steel windows have been removed from the BTS vacuum system to reduce the transverse dimensions of the injected beam.

• M.W. McGee
  Fermilab, Batavia
• R. Amirikas, M. Boehnert, C. Engling, D. Hoppe, K. Jensch, D. Kostin, C. Mueller, H. Remde, O. Sawlanski, J. Wojtkiewicz
  DESY, Hamburg
• S. Barbanotti, A. Bosotti, M. Fusetti, P.M. Michelato
  INFN/LASA, Segrate (MI)
• S. Berry, M. Dorlot, O. Napoly, C.G. Thomas-Madec
  CEA, Gif-sur-Yvette
• A. Bertolini
  Albert Einstein, Leibniz Universität, Hannover

With a view to the series production of one hundred, 12 m long XFEL 1.3 GHz cryomodules and their transportation from the assembly site at CEA Saclay (F) to the installation site at DESY Hamburg (D) a test transportation of a FLASH cryomodule has been performed, in the condition foreseen for the mass transportation. The present study examines the stresses induced on the module and verify the damping capabilities of the transport frame in order to minimize risk of damage to the most critical components. During the transportation, acceleration and vibration have been monitored as well as coupler antenna contacts and vacuum performances. This paper describes the analysis performed and compares those results to the data of a similar transportation study at Fermilab for the CM1 cryomodule.

• M.W. McGee, T.T. Arkan, E. Borissov, J.R. Leibfritz, W. Schappert
  Fermilab, Batavia
• S. Barbanotti
  INFN/LASA, Segrate (MI)

Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02- 07CH11359 with the U.S. Department of Energy.

In an exchange of technology agreement, Deutsches Elektron-Synchrotron (DESY) Laboratory in Hamburg Germany has provided a 1.3 GHz cryomodule “kit” to Fermilab. The cryomodule components (qualified dressed cavities, cold mass parts, vacuum vessel, etc.) sent from Germany in pieces were assembled at Fermilab’s Cryomodule Assembly Facility (CAF). The cavity string was assembled at CAF-MP9 Class 10 cleanroom and then transported to CAF-ICB cold mass assembly area via a flatbed air ride truck. Finite Element Analysis (FEA) studies were implemented to define location of instrumentation for initial coldmass transport, providing modal frequencies and shapes. Subsequently, the fully assembled cryomodule CM1 was transported to the SRF Accelerator Test Facility at New Muon Lab (NML). Internal geophones (velocity sensors) were attached during the coldmass assembly for transport (warm) and operational (cold) measurements. A description of the isolation system that maintained alignment during transport and protected fragile components is provided. Shock and vibration measurement results of each transport and modal analysis are discussed.

• M.W. McGee, J. Grimm, D.R. Olis, W. Schappert
  Fermilab, Batavia

Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02- 07CH11359 with the U.S. Department of Energy.

In an exchange of technology agreement, Fermilab has built and delivered a 3.9 GHz (3rd harmonic) cryomodule to Deutsches Elektron-Synchrotron (DESY) Laboratory to be installed in the TTF/FLASH beamline. Transport to Hamburg, Germany was completed via a combination of flatbed air ride truck and commercial aircraft, while minimizing transition or handling points. Initially, destructive testing of fragile components, transport and corresponding alignment stability studies were performed in order to assess the risk associated with transatlantic travel of a fully assembled cryomodule. Data logged tri-axial acceleration results of the transport with a comparison to the transport study predicted values are presented.

• J.W. Glenn, H. Huang, A.K. Jain, C.J. Liaw, I. Marneris, W. Meng, J.-L. Mi, S.P. Pontieri, P.J. Rosas, J. Sandberg, J.E. Tuozzolo, W. Zhang
  BNL, Upton, Long Island, New York

Funding: Work supported by Brookhaven Science Associates, LLC underContract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

In order to cross more rapidly the 82 weak resonances caused by the horizontal tune and the partial snakes, we plan to jump the horizontal tune 82 times during the acceleration cycle, 41 up and 41 down*. To achieve this, the magnets creating this tune jump will pulse on in 100 micro-seconds, hold the current flat for about four milli-seconds and zero the current in another 100 micro-seconds. The magnets are old laminated beam transport magnets with longitudinal shims closing the aperture to reduce inductance and power supply current. The power supply uses a high voltage capacitor discharge to raise the magnet current, which is then switched to a low voltage supply, and then the current is switched back to the high voltage capacitor to zero the current. The current in each of the magnet pulses must match the order of magnitude change in proton momentum during the acceleration cycle. The magnet, power supply and cabling will be described with coast saving features and operational experience.

*Overcome Horizontal Depolarizing Resonances in the AGS with Tune Jump

• W. Kang, Y. Hao, L.H. Huo, J.X. Song, L. Wang
  IHEP Beijing, Beijing

China Spallation Neutron Source is a high intensity beam facility planed to build in future in China. It is composed of Linac, RCS and target station. The beam extraction from the RCS will be realized by ten vertical kicker magnet and one Lambertson magnet. One prototype kicker magnet has been successfully designed and developed in Institute of High Energy Physics. In this paper, the physical and structural design of the prototype kicker magnet are presented, and issues of the magnet development, construction and test are discussed.

• S. Kwiatkowski, K.M. Baptiste, J. Julian
  LBNL, Berkeley, California

Funding: *Work supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Science and Engineering Division, of the Department of Energy under contract No. DE-AC02-05CH11231.

ALS is the 1.9GeV third generation synchrotron light source which has been operating since 1993 at Berkeley National Lab. Our team is now working on the design of a new RF power source (replacement of the existing 320kW klystron with 4 IOT’s). In the new design the existing conventional crow-bar klystron protection system will be replaced with a fast disconnect switch. The switch will be constructed out of 16 high-voltage IGBT’s connected in series equipped with static and dynamic balancing system. The main advantage of using this new technology is faster action and virtually no stress for the components of the high voltage power supply. This paper will describe the hardware design process and the test results of the prototype switch unit.

• J. Rochford
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• I.R. Bailey
  Lancaster University, Lancaster
• E. Baynham, T.W. Bradshaw, A.J. Brummitt, D.A. Burton, F.S. Carr, A.J. Lintern
  STFC/RAL, Chilton, Didcot, Oxon
• J.A. Clarke, O.B. Malyshev, D.J. Scott, B.J.A. Shepherd
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• Y. Ivanyushenkov
  ANL, Argonne
• G.A. Moortgat-Pick
  Durham University, Durham
• N.C. Ryder
  University of Bristol, Bristol

The ILC positron source relies upon a ~200 m long superconducting helical undulator in order to generate the huge flux of gamma photons required. The period is only 11.5 mm but the field strength is ~1 T. The UK is building and testing a full scale 4 m long ILC cryomodule at the moment. It will be completed in 2008 and the results used to demonstrate the feasibility of the full (200 m long) system.

Slides

• T. Tanaka, T. Hara
  RIKEN/SPring-8, Hyogo
• T. Bizen, H. Kitamura, T. Seike
  JASRI/SPring-8, Hyogo-ken

Several labs are pursuing the concept of cooling permanent magnet undulators down to cryogenic temperatures in order to increase the remnant field of the material and so the on-axis field strength. This talk will review the progress made in this field, experimental magnet field data will be available to show the real performance of such a device and show whether they can be built and shimmed at room temperature and operated at cryotemperatures.

Slides

• S.G. Tantawi
  SLAC, Menlo Park, California

This talk will summarize progress towards high-gradient accelerator structures for a future multi-TeV linear collider. The research summarized will include the US high gradient research collaboration and the CLIC research program, and will include recent experimental results of testing a variety of accelerator structures with different frequencies, geometries and materials, and features that allow for wake field damping. The talk also presents the results of specialized material studies geared towards the understanding of surface fatigue limits due to high magnetic fields, and progress on the theory of rf breakdown in high vacuum structures and multipactoring in dielectric loaded structures.

Slides

• I. Syratchev, E. Adli, A. Cappelletti, S. Döbert, G. Riddone, W. Wuensch
  CERN, Geneva
• V.A. Dolgashev, J.R. Lewandowski, S.G. Tantawi
  SLAC, Menlo Park, California
• R.J.M.Y. Ruber, V.G. Ziemann
  Uppsala University, Uppsala

A fundamental element of the CLIC concept is two-beam acceleration, where rf power is extracted from a high-current and low-energy beam in order to accelerate the low-current main beam to high energy. The power extraction occurs in special X-band Power Extraction and Transfer Structures (PETS). The structures are large aperture, high-group velocity and overmoded periodic structures. Following the substantial changes of the CLIC baseline parameters in 2006, the PETS design has been thoroughly updated along with the fabrication methods and corresponding rf components. Two PETS prototypes have been fabricated and high power tested. Test results and future plans are presented.

Slides

• T.W. Habermann, A. Balkcum, R. Begum, H.P. Bohlen, M. Cattelino, E. Cesca, L. Cox, E.L. Eisen, S. Forrest, D. Gajaria, T. Kimura, J.L. Ramirez-Aldana, A. Staprans, B. Stockwell, L. Zitelli
  CPI, Palo Alto, California

Funding: The authors would like to thank DESY for their support. In addition, we appreciate SLAC helping us out with test equipment.

CPI has designed and is currently in the process of building a prototype of a horizontally oriented multiple beam klystron (MBK) required to provide at least 10 MW peak rf output and 65% efficiency at 1300 MHz and 1.5% rf duty. The klystron was ordered by DESY for the European XFEL. In our design six off-axis electron beams go through seven ring resonators operating in the fundamental-mode. This ensures sufficient beam separation for longer cathode life while keeping the overall diameter of the device small. The MBK was designed using sate-of-the-art multi-dimensional design codes which showed that it was exceeding all performance requirements. First rf hot test data at reduced duty produced 11.2 MW peak saturated rf output and 74% efficiency, which was however accompanied by high beam interception. Initial optimization of the electromagnet resulted in a 70% reduction of the rf body current, but at the expense of rf output power, efficiency (down to 67%) and gain. The magnetic field balance has to be further optimized for low body current and high efficiency at all required operating conditions. Complete test data after optimization and tuning will be presented at the conference.

Slides

• J.M. Jimenez
  CERN, Geneva

With the successful circulation of beams in the Large Hadron Collider (LHC), its vacuum system becomes the World’s largest vacuum system under operation. This system is composed of 54 km of UHV vacuum for the two circulating beams and about 50 km of insulation vacuum around the cryogenic magnets and the liquid helium transfer lines. The LHC complex is completed by 7 km of high vacuum transfer lines for the injection of beams from the SPS and their dumping. Over the 54 km of UHV beam vacuum, 48 km are at cryogenic temperature (1.9 K), the remaining 6 km are at ambient temperature and use extensively non-evaporable getter (NEG) coatings, a technology that was born and industrialised at CERN. The cryogenic insulation vacuums, less demanding technically, impress by their size and volume: 50 km and 15000 m3. Once cooled at 1.9 K, the cryopumping allows reaching pressure in the 10^-4 Pa range. This paper describes the LHC vacuum system, its behaviour in presence of beams as well as the detailed actions undertaken to recover its integrity after the electrical short which happened in a quadrupole bus-bar on 19th of September 2008.

Slides

• G.-Y. Hsiung, C.K. Chan, C.-C. Chang, C.L. Chen, S-N. Hsu, C.Y. Yang
  NSRRC, Hsinchu
• J.-R. Chen
  National Tsing Hua University, Hsinchu

The Taiwan Light Source (TLS), a third generation accelerator, has been operated successfully since 1993. It has been upgraded to increase the beam energy from 1.3 GeV to 1.5 GeV and the consequent capability of full energy injection afterwards. While the beam current has been increased from 200 mA to 300 mA after replacement of RF cavities with superconducting one. The vacuum pressure tends to decrease continuously after installations of 3 undulators and 4 wigglers as well as the new front ends. The accumulated beam dose increased faster up to > 14500 Ah after the routine operational top-up mode since 2006 with average pressure has been maintained below 0.13 nPa/mA. The beam life time of 6 hours at 300 mA has been kept with a limitation of Touschek life time at a stable beam with variation of photon flux < 0.05%. However, the photon absorbers of front ends have been replaced with new ones for subjecting the higher irradiation power after upgrading. The good dynamic pressure reflects the effective pumping performance. The experiences of components failures will be summarized in this paper.

Slides

• F. Herfurth, W.A. Barth, G. Clemente, L.A. Dahl, P. Gerhard, M. Kaiser, H.J. Kluge, S. Koszudowski, C. Kozhuharov, W. Quint, A. Sokolov, T. Stöhlker, G. Vorobjev
  GSI, Darmstadt
• O.K. Kester
  NSCL, East Lansing, Michigan
• J. Pfister, U. Ratzinger, A.C. Sauer, A. Schempp
  IAP, Frankfurt am Main

Funding: European Commission; contract number HPRI-CT-2001-50036 (HITRAP) German Ministry for Education and Research (BMBF; contract number 06 FY160I

Deceleration of heavy, highly charged ions from the ion storage ring ESR of the GSI accelerator facility with an rf-linear decelerator will provide ions up to bare uranium almost at rest for cutting edge experiments in atomic and nuclear physics. For this unique approach the beam has to be prepared well by electron cooling in the ESR to account for a 26 time increase of the transverse emittance during the following deceleration. An interdigital H-type (IH) structure and a radio-frequency quadrupole (RFQ) structure are operated in inverse to decelerate first from 4 MeV/u to 0.5 MeV/u and then to 6 keV/u. The quasi-continuous beam from the ESR is adapted, by using a double drift buncher, to match the longitudinal acceptance of the IH. Downstream from the IH-structure the 0.5 MeV/u beam is then fit with a spiral re-buncher to the RFQ, which finally decelerates the ions to 6 keV/u. First commissioning beam times have shown that the bunching works well and ions have been decelerated to 0.5 MeV/u in the IH structure. Extensive measurements of transversal emittance before and after deceleration can now be compared to beam dynamics calculations.

Slides

• W. Kaabi, H. Jenhani, A. Variola
  LAL, Orsay
• G. Keppel, V. Palmieri
  INFN/LNL, Legnaro (PD)

LAL-Orsay is developing an important effort on R&D studies on RF power couplers. One of the most critical components of those devices is the ceramic RF window that allows the power flux to be injected in the coaxial line. The presence of a dielectric window on a high power RF line has a strong influence on the multipactor phenomena. To reduce this effect, the decrease the secondary emission yield (SEY)of the ceramic window is needed. Due to its low SEY coefficient, TiN coating is used for this goal. In this framework, a TiN sputtering bench has been developed in LAL. The reactive sputtering of TiN needs the optimisation of gas flow parameters and electrical one, to obtain stoechiometric deposit. XRD analysis was performed to control the film composition and stoechiometry. Measurements point out how the Nitrogen vacancy on the film can be controlled acting on the N2 flow. In addition, the coating thickness must be optimized so that the TiN coating effectively reduces the SEY coefficient but does not cause excessive heating, due to ohmic loss. For this purposes, multipactor level breakdown and resistance measurements were done for different deposit thickness.

• M. BastaniNejad, A.A. Elmustafa
  Old Dominion University, Norfolk, Virginia
• M. Alsharo'a, R.P. Johnson, M.L. Neubauer, R. Sah
  Muons, Inc, Batavia
• M. Chung, M. Hu, A. Jansson, A. Moretti, M. Popovic, K. Yonehara
  Fermilab, Batavia

Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86350 Supported in part by USDOE STTR Grant DE-FG02-08ER86352 and in part by FRA DOE contract number DE-AC02-07CH11359

In earlier reports, microscopic images of the surfaces of metallic electrodes used in high-pressure gas-filled 805 MHz RF cavity experiments were used to investigate the mechanism of RF breakdown of tungsten, molybdenum, and beryllium electrode surfaces. Plots of remnants were consistent with the breakdown events being due to field emission, due to the quantum mechanical tunnelling of electrons through a barrier as described by Fowler and Nordheim. In the work described here, these studies have been extended to include tin, aluminium, and copper. Contamination of the surfaces, discovered after the experiments concluded, have cast some doubt on the proper qualities to assign to the metallic surfaces. However, two significant results are noted. First, the maximum stable RF gradient of contaminated copper electrodes is higher than for a clean surface. Second, the addition of as little as 0.01% of SF6 to the hydrogen gas increased the maximum stable gradient, which implies that models of RF breakdown in hydrogen gas will be important to the study of metallic breakdown

• M. BastaniNejad, A.A. Elmustafa
  Old Dominion University, Norfolk, Virginia
• J.M. Byrd, D. Li
  LBNL, Berkeley, California
• M.E. Conde, W. Gai
  ANL, Argonne
• R.P. Johnson, M.L. Neubauer, R. Sah
  Muons, Inc, Batavia
• A. Moretti, M. Popovic, K. Yonehara
  Fermilab, Batavia

Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86352 and FRA DOE contract number DE-AC02-07CH11359

Many present and future particle accelerators are limited by the maximum electric gradient and peak surface fields that can be realized in RF cavities. Despite considerable effort, a comprehensive theory of RF breakdown has not been achieved and mitigation techniques to improve practical maximum accelerating gradients have had only limited success. Recent studies have shown that high gradients can be achieved quickly in 805 MHz RF cavities pressurized with dense hydrogen gas without the need for long conditioning times, because the dense gas can dramatically reduce dark currents and multipacting. In this project we use this high pressure technique to suppress effects of residual vacuum and geometry found in evacuated cavities to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of magnetic field, frequency, and surface preparation. A 1.3-GHz RF test cell with replaceable electrodes (e.g. Mo, Cu, Be, W, and Nb) and pressure barrier capable of operating both at high pressure and in vacuum been designed and built, and preliminary testing has been completed. A series of detailed experiments is planned at the Argonne Wakefield Accelerator.

• P. Frigola, R.B. Agustsson, S. Boucher, A.Y. Murokh
  RadiaBeam, Marina del Rey
• H. Badakov, A. Fukasawa, P. Musumeci, J.B. Rosenzweig, G. Travish
  UCLA, Los Angeles, California
• D. Cormier, T. Mahale
  NCSU, Raleigh, North Carolina
• L. Faillace
  INFN/LNF, Frascati (Roma)

Electron beam based additive fabrication techniques have been successfully applied to produce a variety of complex, fully dense, metal structures. These methods, collectively known as Solid Freeform Fabrication (SFF) are now being explored for use in radio frequency (RF) structures. SFF technology may make it possible to design and produce near-netshape copper structures for the next generation of very high duty factor, high gradient RF photoinjectors. The SFF process discussed here, Arcam Electron Beam Melting (EBM), utilizes an electron beam to melt metal powder in a layer-by-layer fashion. The additive nature of the SFF process and its ability to produce fully dense parts are explored for the fabrication of internal cooling passages in RF photoinjectors. Following an initial feasibility study of the SFF process, we have fabricated a copper photocathode, suitable as a drop-in replacement for the UCLA 1.6 cell photoinjector, with internal cooling channels using SFF. Material analysis of the prototype cathode and new designs for a high duty factor photoinjector utilizing SFF technology will be presented.

• C. Adolphsen, A.A. Haase, D. Kiehl, C.D. Nantista, T.N. Nieland, J. Tice, F. Wang
  SLAC, Menlo Park, California

Funding: Work supported by the DOE under contract DE-AC02-76SF00515

A new facility to clean, assemble, bake and rf process TTF3-style power couplers has been completed and is in operation at SLAC. This facility includes a class-10 cleanroom, bake station and an L-band source capable of producing up to 4 MW pulses. This paper describes the facility, test results from processing pairs of couplers that will be used in cryomodules at FNAL, and efforts to simplify the design and manufacturing of the couplers for large scale use at ILC. Also, tests of the couplers to explore their power limits for use in an FNAL superconducting proton linac are presented.

• E. Rampnoux, S. Berthelot, P. Blache, S. Bousson, J. Lesrel, L. Lukovac, G. Olry
  IPN, Orsay

Funding: EURISOL Project

The development of RF power couplers for superconducting low-beta SPOKE cavities, performed at Nuclear Physics Institute in Orsay in the framework of the EURISOL Design Study, has led to the design of a 20 kW RF power coaxial coupler showing very good RF performances and the implementation of a test stand to condition two of these couplers at 20 kW CW power in the traveling wave mode at 352,2 MHz by using a half-wave resonant cavity. Composed by a ceramic disk, the coaxial power coupler developed shows on one hand a very good 50 ohms matching on a large bandwidth like 760 MHz, after an electromagnetic optimisation of the window area, and on the other hand a simplified design with regard to the classic coaxial couplers. Characteristics of the power coupler and the test stand will be described, and the low RF power test of the coaxial window and the conditioning at high RF power of two couplers will be presented.

• T. Tajima, A.S. Bhatty, P. Chacon, R.L. Edwards, G.V. Eremeev, F.L. Krawczyk, R.J. Roybal, J.D. Sedillo
  LANL, Los Alamos, New Mexico
• W.A. Clemens, P. Kneisel, R. Manus, R.A. Rimmer, L. Turlington
  JLAB, Newport News, Virginia

Funding: DTRA

805 MHz elliptical SRF cavities have been used for SNS as the first application for protons. At LANL, an R&D started to explore a capability of getting high-gradient cavities (40-50 MV/m) at this frequency for the future applications such as proton and muon based interrogation testing facility added to the LANSCE accelerator and a power upgrade of the LANSCE accelerator for the fission and fusion material test station. Optimized cell designs for “standard”, “low-loss” and “re-entrant” shapes, cavity test results for “standard” single-cell cavities with temperature mapping as well as surface inspection results will be presented.

• J. Popielarski, C. Compton, W. Hartung, M.J. Johnson, F. Marti, J.C. Oliva, R.C. York
  NSCL, East Lansing, Michigan

A medium-velocity half wave resonator has been designed and prototyped at the National Superconducting Cyclotron Laboratory for use in a heavy ion linac. The cavity is designed to provide 3.7 MV of accelerating voltage at an optimum beta = v/c = 0.53, with peak surface electric and magnetic fields of 32.5 MV/m and 79 mT, respectively. The resonant frequency is 322 MHz. The cavity was designed to reduce sensitivity to bath pressure fluctuations while maintaining a structure that can be easily fabricated, cleaned, and tuned. Deep draw forming dies and a copper cavity prototype were fabricated to confirm tolerances and formability. A prototype tuner was built; the helium vessel and power coupler have been designed. Measurements were performed to confirm finite element predictions for the mechanical modes, bath pressure sensitivity, tuner stiffness, and tuning range.

• M.L. Neubauer
  Muons, Inc, Batavia
• R.A. Rimmer
  JLAB, Newport News, Virginia

Funding: Supported in part by DOE SBIR grant DE-FG02-08ER85171 Supported in part by USDOE Contract DE-AC05-84-ER-40150

There are over 35 coupler designs for SRF cavities ranging in frequency from 325 to 1500 MHz. Two-thirds of these designs are coaxial couplers using disk or cylindrical ceramics in various combinations and configurations. While it is well known that dielectric losses go down by several orders of magnitude at cryogenic temperatures, it not well known that the thermal conductivity also goes down, and it is the ratio of thermal conductivity to loss tangent (SRF ceramic Quality Factor) and ceramic volume which will determine the heat load of any given design. We describe a novel robust co-axial SRF coupler design which uses compressed window technology. This technology will allow the use of highly thermally conductive materials for cryogenic windows. The mechanical designs will fit into standard-sized ConFlat® flanges for ease of assembly. Two windows will be used in a coaxial line. The distance between the windows is adjusted to cancel their reflections so that the same window can be used in many different applications at various frequencies.

• P. Goudket, S.C. Appleton, R. Bate, C.D. Beard, B.D. Fell, J.-L. Fernandez-Hernando, P.A. McIntosh, S.M. Pattalwar
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• P.K. Ambattu, G. Burt, A.C. Dexter, B.D.S. Hall, M.I. Tahir
  Cockcroft Institute, Lancaster University, Lancaster

The ILC crab cavities require very tight phase control in order to operate within the ILC parameters. In order to verify that the phase control system met the design tolerances, two single-cell niobium 3.9GHz superconducting dipole-mode cavities were tested in a liquid helium cryostat. The preparation of the cavities, design of the testing apparatus and performance of the phase control system are described in this paper.

• X. Huang, J.A. Safranek
  SLAC, Menlo Park, California

A preliminary plan for an infrared or terahertz beamline at SSRL is studied. Using chicane in a straight section allows us to redesign a section of the vacuum chamber and extract infrared/terahertz beam with a large acceptance. Under the low alpha operational mode, the terahertz beam power can be greatly enhanced by the coherent synchrotron radiation (CSR) effect. Calculations of photon beam flux and brightness and the shielding and CSR effects are presented.

• J.-M. Filhol, J.C. Besson, P. Brunelle, L. Cassinari, M.-E. Couprie, J.-C. Denard, C. Herbeaux, N. Hubert, J.-F. Lamarre, J.-P. Lavieville, P. Lebasque, M.-P. Level, A. Loulergue, P. Marchand, A. Nadji, L.S. Nadolski, R. Nagaoka, M.-A. Tordeux
  SOLEIL, Gif-sur-Yvette

After two years of operation, the SOLEIL 3rd generation synchrotron light source is delivering photons to 20 beamlines with a current of 250mA in multibunch or hybrid modes, and 60 mA in 8 bunch mode. The radiation control of the beamline hutches is performed at 300 mA, but recently a 455mA current was stored during machine tests following the installation of the second RF cryomodule. It is foreseen to reach the maximum current of 500mA in the early 2009 and to operate in top-up mode from then on. The new transverse feedback loop has enabled to improve the performance of the single bunch and multibunch beams. The beam position stability is in the range of few micrometers thanks to the efficiency of the fast orbit feedback. Fifteen insertion devices are now installed in the storage ring, ten others are under construction, and a cryogenic undulator is under development. A big effort is being taken in order to compensate the effects of these insertion devices on the machine performance. The good operation performance achieved in 2007 (first year) has been improved in 2008 during which ~4 000 hours will have been delivered to the users with a 95.5% availability and a 30 hours MTBF.

• A. Nadji
  SOLEIL, Gif-sur-Yvette
• T.H. Abu-Hanieh, A. Al-Adwan, M.A. Al-najdawi, A. Amro, M. Attal, S. Budair, D.S. Foudeh, A. Hamad, A. Kaftoosian, T.A. Khan, F. Makahleh, S.A. Matalgah, M. Sbahi, M.M. Shehab, H. Tarawneh, S. Varnasseri
  SESAME, Allan

SESAME is a 3rd generation synchrotron light source facility under construction in Allan, Jordan, 30 km North-West of Amman. SESAME consists of a 2.5 GeV storage ring, a 22.5 MeV Microtron and an 800 MeV Booster. The Microtron was installed at its final position and its subsystems have been successfully tested. The commissioning with beam of the Microtron will start in March 2009. The installation of the Booster is expected to take place in summer 2009. Most of the storage ring subsystems are ready for call for tender. The progress of SESAME project including beamlines status will be reported in this paper.

• Zh.S. Gevorkian, S.G. Arutunian, K.B. Oganesyan
  YerPhI, Yerevan

Diffusive Radiation is originated by the passage of charged particles through a randomly inhomogeneous medium. DR appears when the conditions for multiple scattering of pseudophotons are fulfilled in the medium. Such a situation can be realized when a charged particle slides over a rough surface. One of the important properties of DR is that the maximum of emission lies at large angles from particle velocity direction. Therefore it can be used for detection of beam touch to the accelerators vacuum chamber wall in case when generated photons will be observed on the opposite side of vacuum chamber. Such a diagnostics can be especially useful for observation of storage rings beam halo.

• M. White, J.T. Collins, P.K. Den Hartog, M.S. Jaski, G. Pile, B.M. Rusthoven, S.E. Shoaf, S.J. Stein, E. Trakhtenberg, J.Z. Xu
  ANL, Argonne

Funding: Work at Argonne was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No DE-AC02-06CH11357.

The Linac Coherent Light Source (LCLS), now being commissioned at the Stanford Linear Accelerator Center (SLAC) in California, and coming online for users in the very near future, will be the world’s first x-ray free-electron laser user facility. Design and production of the undulator system was the responsibility of a team from the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). A sophisticated, five-axis, computer-controlled support and motion system positions and stabilizes all beamline components in the undulator system. The system also enables undulators to be retracted from the beam by 80 mm without disturbing the rest of the beamline components. An overview of the support and motion system performance, including achieved results with a production unit that was reserved at Argonne for this purpose, is presented.

• C. Boffo, M. Borlein, W. Walter
  BNG, Würzburg
• T. Baumbach, A. Bernhard
  KIT, Karlsruhe
• S. Casalbuoni, A.W. Grau, M. Hagelstein, R. Rossmanith
  FZK, Karlsruhe
• E.M. Mashkina
  University Erlangen-Nuernberg, Erlangen

Superconducting insertion devices (IDs) are very attractive for synchrotron light sources since they allow increasing the flux and/or the photon energy with respect to permanent magnet IDs. Babcock Noell GmbH (BNG) is completing the fabrication of a 1.5 m long unit for ANKA at FZK. The period length of the device is 15 mm for a total of 100.5 full periods plus an additional matching period at each end. The key specifications of the system are: a K value higher than 2 and the capability of withstanding a 4 W beam heat load and a phase error of 3.5 degrees. In addition, during the injection phase of the machine, the nominal gap of 5 mm can be increased up to 25 mm. The magnets have been tested with liquid helium in a vertical dewar and are now being installed in the cryostat. This paper describes the technical design concepts of the device and the status of the assembly process.

• G. Lebec, J. Chavanne, C. Penel, F. Revol
  ESRF, Grenoble
• C.A. Kitegi
  SOLEIL, Gif-sur-Yvette

A cryogenically cooled in-vacuum undulator was installed in the ID6 test beamline of the ESRF in January 2008. This 2 metre long hybrid undulator has a period of 18 mm. The magnetic assembly is based on NdFeB permanent magnets cooled at a temperature close to 150 K . A liquid nitrogen closed loop is used for the cooling of the undulator. This cooling system is well adapted for achieving a uniform temperature along the magnetic assembly. An important part of the study was focused on the heat budget of the undulator under beam in the different filling modes delivered at the ESRF. The impact of the undulator on the ultra high vacuum of the ring was investigated with several warming/cooling cycles. This paper presents the main outcomes from this first experience.

• M. Hagelstein, T. Baumbach, S. Casalbuoni, A.W. Grau, B. Kostka, R. Rossmanith, D. Saez de Jauregui
  FZK, Karlsruhe
• A. Bernhard, D. Wollmann
  KIT, Karlsruhe
• J. Chavanne, P. Elleaume
  ESRF, Grenoble
• B. Diviacco
  ELETTRA, Basovizza
• E.M. Mashkina
  University Erlangen-Nurnberg, Institute of Condensed Matter Physics, Erlangen
• E.J. Wallén
  MAX-lab, Lund

Within the framework of a joint research activity of the European project IA-SFS (RII3-CT2004-506008) four synchrotron facilities have jointly developed diagnostic systems for superconducting undulators. Four work packages have been successfully completed: Design and construction of a test cryostat for field measurements; design and construction of a mock-up coil; field measurement and field error compensation; diagnostics and measurement of the spectrum of low energy electrons responsible for beam heat load in a superconducting undulator. The development advanced the knowledge of magnetic field error compensation considerably and might be of help in understanding the different beam heat load sources. Based on the development a second generation planar superconducting undulator with 15 mm period length for the synchrotron light source ANKA has been specified and procured.

• S. Casalbuoni, M. Hagelstein, D. Saez de Jauregui, S. Schleede
  FZK, Karlsruhe

Preliminary studies performed with the cold bore superconducting undulator installed in the ANKA storage ring suggest that the beam heat load is mainly due to the electron wall bombardment. Electron bombardment can both heat the cold vacuum chamber and induce an increase in the pressure because of gas desorption. In this contribution we compare the measurements of the pressure in a cold bore performed in the electron storage ring ANKA with the prediction obtained using the equations of gas dynamic balance in a cold vacuum chamber exposed to synchrotron radiation and electron bombardment. The balance results from two competitive effects: the photon and electron desorption of the gas contained in the oxide layer of the chamber wall and of the gas cryosorbed, and the cryopumping of the cold surface. We show that photodesorption alone cannot explain the pressure rise observed and that electron multipacting is needed.

• T. Kii, M. A. Bakr, K. Higashimura, R. Kinjo, K. Masuda, H. Ohgaki, T. Sonobe, K. Yoshida
  Kyoto IAE, Kyoto
• H. Zen
  UVSOR, Okazaki

A short period undulator with strong magnetic field will play an important role in future light source. We proposed a new type of staggered array undulator by use of bulk high-Tc superconductor*. We have constructed a prototype of the undulator using DyBaCuO bulk superconductors and a normal conducting solenoid. In the conference, we will present results of the magnetic field measurement and discuss on the feasibility of the new type bulk high-Tc staggered array undulator.

*R. Kinjo et al., Proceedings of the FEL2008, in press.

• S. Prestemon, D.R. Dietderich, A. Madur, S. Marks, D. Schlueter
  LBNL, Berkeley, California

Funding: This work was supported by the Director, Office of Science, U.S. Department of Energy, under contract No. DE-AC02-05CH11231.

Superconducting undulators are currently under development at a number of light sources to serve as the next generation of insertion devices, with higher fields providing enhanced spectral range for users. Most of these devices are designed with wire-based technologies appropriate for periods greater than ~10mm. New undulator concepts yielding very short-period, high-field devices with periods of a few millimeters and a K~1 have the potential to significantly reduce the cost and enhance the performance of FEL's. Here we describe a design using high temperature superconductor tapes that are commercially available, and that promise a cost-effective fabrication process using micromachining or lithography. Detailed magnetic and spectral performance analysis will be provided.

• F. Marteau, C. Benabderrahmane, P. Berteaud, F. Briquez, P. Brunelle, L. Chapuis, M.-E. Couprie, T.K. El Ajjouri, J.-M. Filhol, C.A. Kitegi, O. Marcouillé, M. Massal, A. Nadji, L.S. Nadolski, R. Nagaoka, K. Tavakoli, M. Valléau, J. Vétéran
  SOLEIL, Gif-sur-Yvette
• O.V. Chubar
  BNL, Upton, Long Island, New York

SOLEIL storage ring presents a very high fraction of the total circumference dedicated to accommodate insertion devices. Over the presently planned 25 insertion devices presenting a large variety of systems, 15 have been already installed and commissioned by the end of 2008. The UV-VUV region is covered with electromagnetic devices (one HU640 and 3 HU256), offering tuneable polarisations. An electromagnet/permanent magnet undulator using copper sheets as coils for fast switching of the helicity is under construction. 13 APPLE-II types undulators, with period ranging from 80 down to 36 mm, provide photons in the 0.1-10 keV region, some of them featuring tapering or quasi-periodicity. 5 U20 in-vacuum undulators cover the 3-30 keV range whereas an in-vacuum wiggler, with magnetic forces compensation via adequate springs is designed to cover the 10^-50 keV spectral domain. R&D on cryogenic in-vacuum undulator has also been launched. A magnetic chicane using permanent magnet dipoles has also been designed in order to accommodate two canted undulators on the same straight section. The processes for optimizing the insertion devices and their achieved performances will be described.

• A.-L. Perrot, R. Appleby, D. Macina
  CERN, Geneva

Several forwards detectors have been installed in the LHC long straight sections located on each side of the experimental caverns. Most of these detectors have been designed by the LHC experiments to study the forwards physics while some of them are dedicated to the measurement of the LHC luminosity. The integration and installation of the forwards detectors have required an excellent coordination between the experiments and the different CERN groups involved into the design and installation of the LHC accelerator. In some cases the integration of these detectors has required a modification of the standard beam lines in order to maximise the physics potentiality of the detectors. Finally, additional systems have been installed in the LHC tunnel to ensure the operation of the forwards detectors in a high radiation environment.

• Yu.A. Kubyshin, A. Crisol, X. Gonzalez Arriola, J.P. Rigla, F. Roure
  UPC, Barcelona
• A.V. Aloev, V.I. Shvedunov
  MSU, Moscow
• J. Berenguer Sau, G. Montoro
  EPSC, CASTELLDEFELS
• D. Carrillo, L. García-Tabarés, F. Toral
  CIEMAT, Madrid
• J. Lucas
  Elytt Energy, Madrid

A compact race-track microtron (RTM) with the maximal output energy 12 MeV is under construction at the Universitat Politècnica de Catalunya (UPC) in collaboration with the Skobeltsyn Institute of Nuclear Physics of the Moscow State University, CIEMAT and a few Spanish industrial companies and medical centers. The RTM end magnets are four-pole systems with the magnetic field created by a rare-earth permanent magnet material. As a source of electrons a 3D off-axis electron gun is used. These elements together with a C-band accelerating structure, dipole magnets, which allow to extract the electron beam with energy from 6 MeV to 12 MeV in 2 MeV step, and a focusing quadrupole are placed inside a vacuum chamber. We report on the current status of the technical design and results of tests of some of the components.

• N. Ohuchi, H. Hayano, N. Higashi, H. Nakai, K. Tsuchiya, A. Yamamoto
  KEK, Ibaraki
• T.T. Arkan, H. Carter, M.S. Champion, J. Grimm, J.S. Kerby, D.V. Mitchell, T.J. Peterson, M.C. Ross
  Fermilab, Batavia
• S. Barbanotti, C. Pagani, P. Pierini
  INFN/LASA, Segrate (MI)
• L. Lilje
  DESY, Hamburg

In an attempt at demonstrating an average field gradient of 31.5 MV/m as per the design accelerating gradient for ILC, a program called S1-Global is in progress as an international research collaboration among KEK, INFN, FNAL, DESY and SLAC. The S1-Global cryomodule will contain eight superconducting cavities from FNAL, DESY and KEK. The cryomodule will be constructed by joining two half-size cryomodules, each 6 m in length. The module containing four cavities from FNAL and DESY will be constructed by INFN. The design of this module is based on an improved 3rd generation TTF design. KEK will modify the 6-meter STF cryomodule to contain four KEK cavities. The designs of the cryomodules are ongoing between these laboratories, and the operation of the system is scheduled at the KEK-STF from June 2010. In this paper, the S1-Global cryomodule plan and the module design will be presented. ‘S1-Global collaboration’ as a co-author.

• W. Scandale, E. Laface, R. Losito
  CERN, Geneva

The UA9 experiment intends to assess the possibility of using bent silicon crystals as primary collimators to direct the beam halo onto a secondary absorber, thus reducing outscattering, beam losses in critical regions and radiation load. The experiment will be performed in the CERN-SPS in storage mode with a low intensity 120 GeV/c proton beam. The beam will be perturbed to create a diffusive halo as in the RD22 experiment. The setup consists of four stations. The crystal station contains two goniometers for crystals. The first tracking station houses silicon strip detectors for single particle tracking. The second tracking station contains the same kind of detectors for tracking. The two stations will allow to measure x-x' densities and collimation efficiencies with high precision. The TAL station, at 90 degrees phase advance,is a 600 mm long tungsten secondary collimator. The observables of the experiment are the collimation efficiencies, the measurement of the phase space and the cleaning efficiency deduced from the losses along the ring. We present here the layout of the experiment and the way we expect to collect data in 2009.

• Y. Zhang, Z. Liu, R. Remec
  ORNL, Oak Ridge, Tennessee

Funding: *SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy

The combined time required for diffusion release from target materials and effusive-flow of short-lived ion species must be minimized at ISOL based radioactive ion beam (RIB) facilities. Computational simulation studies with state-of-the-art codes offer cost effective means for designing targets with optimized diffusion release properties and vapor transport systems with short path lengths, as required for such applications. To demonstrate the power of the technique for designing optimum thickness targets, analytic solutions to the diffusion equation are compared with those obtained from a finite-difference code for radioactive particle release from simple geometries. The viability of the Monte Carlo technique as a practical means for optimally designing vapor transport systems is demonstrated by simulating the effusive-flow of neutral particles through several complex vapor transport systems. Important issues which affect the yield rates of short-lived species generated in high power ISOL targets are also discussed.

• J.C. Smith, L. Keller, S.A. Lundgren, T.W. Markiewicz
  SLAC, Menlo Park, California
• L. Lari
  EPFL, Lausanne

Funding: Work supported in part by the U.S. Department of Energy contract DE-AC02-76SF00515

The Phase II upgrade to the LHC collimation system calls for complementing the 30 high robust Phase I graphite collimators with 30 high Z Phase II collimators. One option is to use metallic rotatable collimators and this design will be discussed here. The Phase II collimators must be robust in various operating conditions and accident scenarios. Design issues include: 1) Collimator jaw deflection due to heating and sagita must be small when operated in the steady state condition, 2) Collimator jaws must withstand transitory periods of high beam impaction with no permanent damage, 3) Jaws must recover from accident scenario where up to 7 full intensity beam pulses impact on the jaw surface and 4) The beam impedance contribution due to the collimators must be small to minimize coherent beam instabilities. The current design will be presented.

• G. Ellwood
  STFC/RAL, Chilton, Didcot, Oxon
• J.-L. Fernandez-Hernando
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• M. Slater, N.K. Watson
  Birmingham University, Birmingham

Spoilers in the ILC Beam Delivery System are required to survive without failure a minimum of 1-2 direct impacts of 250 GeV-500 GeV bunch of electrons or positrons, in addition to maintaining low geometric and resistive wall wake fields. The likelihood of spoiler survival was determined using finite element models of thermal and mechanical properties of the spoilers, with realistic patterns of energy deposition as input. The second phase of an experiment to calibrate the finite element models using electron beam data will be performed in the ATF2 extraction line, by subjecting a small sample of Ti-6Al-4V to bunches of electrons. The displacement of the surface will be measured with a Velocity Interferometer System of Any Reflector (VISAR). This paper shows the project plan as well as results of the simulations and expected readout from the VISAR.

• M.T. Rooney, C.J. Densham
  STFC/RAL, Chilton, Didcot, Oxon
• Y. Yamada
  KEK, Ibaraki

The target station of the T2K neutrino facility requires a beam window to separate the target chamber, containing helium at atmospheric pressure, from the secondary beam line, which is maintained at ultra high vacuum. In addition to withstanding this differential pressure, the window must survive induced stresses due to intense heating resulting from interaction with a 0.75 MW pulsed proton beam. The design consists of a hemispherical double window with forced convection helium cooling in the volume enclosed, manufactured from titanium alloy. Preliminary analysis suggested that 'shock' waves induced by the pulsed nature of the beam will form the dominant mode of stress. The finite element software ANSYS Mechanical (V10) has been used to simulate the effect of beam impingement on a variety of window thicknesses in an attempt to find the optimum geometry. Results have shown that through thickness stress waves can be amplified if successive bunches arrive in phase with the waves generated by previous bunches. Therefore, thickness has been shown to be a critical variable in determining the window’s resistance to induced thermal shock.

• E. Mahner, S. Chemli, P. Cruikshank, D. Forkel-Wirth, J.M. Jimenez
  CERN, Geneva

Beam losses in high-energy particle accelerators are responsible for beam lifetime degradation. In the LHC beam losses will create a shower of particles while interacting with materials from the beam pipes and surroundings, resulting in a partial activation of material in the tunnel. Efforts have been made during the accelerator design to monitor and to reduce the activation induced by beam losses. Traceability for all vacuum components has been established providing a tool to follow-up individually each component or subcomponents installed in the tunnel, regardless of their future destination e.g. recycling or disposal. In the latter case, the history of vacuum components will allow calculating the beam-induced activation and permit comparisons with in-situ and ex-situ measurements. This zoning will also help to reduce collective and individual radiation doses to personnel during interventions. The paper presents the vacuum system layout and describes the LHC vacuum zoning and its implementation using an ORACLE© database.

• C.-J. Jing, F. Gao, A. Kanareykin, A.L. Kustov, P. Schoessow
  Euclid TechLabs, LLC, Solon, Ohio
• M.E. Conde, W. Gai, R. Konecny, J.G. Power
  ANL, Argonne
• S. Kazakov
  KEK, Ibaraki

Funding: DoE SBIR 2008 Phase II, DE-FG02-07ER84821

High frequency, high power rf sources are needed for many applications in particle accelerators, communications, radar, etc. We have developed a 26GHz high power rf source based on the extraction of wakefields from a relativistic electron beam. The extractor is designed to couple out rf power generated from a high charge electron bunch train traversing a dielectric loaded waveguide. Using a 20nC bunch train (bunch length of 1.5 mm) at the Argonne Wakefield Accelerator (AWA) facility, we expect to obtain a steady 26GHz output power of 148 MW. The extractor has been fabricated and bench tested along with a 26GHz Power detector. The first high power beam experiments should be performed prior to the Conference. Detailed results will be reported.

• C.-J. Jing, F. Gao, A. Kanareykin, P. Schoessow
  Euclid TechLabs, LLC, Solon, Ohio
• M.E. Conde, W. Gai, R. Konecny, J.G. Power
  ANL, Argonne

Funding: DoE SBIR Phase I 2008

As the dimensions of accelerating structures become smaller and beam intensities higher, the transverse wakefields driven by the beam become quite large with even a slight misalignment of the beam from the geometric axis. These deflection modes can cause inter-bunch beam breakup and intra-bunch head-tail instabilities along the beam path, and thus BBU control becomes a critical issue. All new metal based accelerating structures, like the accelerating structures developed at SLAC or power extractors at CLIC, have designs in which the transverse modes are heavily damped. Similarly, minimizing the transverse wakefield modes (here the HEMmn hybrid modes in Dielectric-Loaded Accelerating (DLA) structures) is also very critical for developing dielectric based high energy accelerators. We have developed a 7.8GHz transverse mode damped DLA structure. The design and bench test results are presented in the article.

• S.V. Kuzikov, A.A. Vikharev
  IAP/RAS, Nizhny Novgorod
• J.L. Hirshfield
  Yale University, Physics Department, New Haven, CT
• S. Kazakov
  Omega-P, Inc., New Haven, Connecticut

Funding: Sponsored in part by US Department of Energy, Office of High Energy Physics.

A multi-mode cavity design for a two-beam accelerator aimed to achieve an accelerating gradient exceeding 150 MeV/m is reported. The cavity has a square cross section which allows excitation in several equidistantly-spaced eigen modes by a bunched drive beam in such a way that the RF fields reach peak values only during time intervals that can be much shorter than for excitation of a single mode, thus exposing the cavity surfaces to strong fields for shorter times. This feature is expected to raise the breakdown and pulse heating thresholds. In order to measure an increase in breakdown threshold surface electric field due to this reduction of exposure time during each RF period, a high-power experiment is planned. Preliminary calculations show that such a study in which comparison of breakdown threshold would be made of a conventional single-mode cavity with a multi-mode cavity can in principle be carried out using the drive beam of the CTF-3 test stand at CERN.

• I.N. Onishchenko, V. Kiselev, A. Linnik, V. Mirny, V. Uskov
  NSC/KIPT, Kharkov

Essential increase of wakefield intensity at excitation by a long train of relativistic electron bunches when the rectangular dielectric structure is filled with plasma was experimentally observed. A train of bunches was produced by the linear resonant accelerator. Parameters of the beam: energy 4.5 MeV, pulsed current 0.5 A, pulse duration 2 mksec. Such macro-pulse consists of a periodic sequence of 6000 electron bunches. Each electron bunch has duration 60 psec, diameter 1.0 cm, angular spread 0.05 mrad, charge 0.16 nC. Bunches repetition frequency is 2805 MHz. Transit channel for bunches is filled with gas at various pressure. The first portion of the bunches ionizes gas so that plasma frequency is equal to bunch repetition frequency and to the frequency of principal eigen mode of the dielectric structure. Excitation enhancement at such resonant conditions is being studied taking into account the improvement of bunch train propagation in the transit channel and electrodynamics change of the dielectric structure at filling with plasma.

• A.M. Cook, J.B. Rosenzweig, R. Tikhoplav, S. Tochitsky, G. Travish, O. Williams
  UCLA, Los Angeles, California

Funding: Work supported by DOE.

We report experimental observation of narrow-bandwidth pulses of coherent Cherenkov radiation produced when a sub-picosecond electron bunch travels along the axis of a hollow circular cylindrical dielectric-loaded waveguide. For an appropriate choice of dielectric structure properties and driving electron beam parameters, the device operates in a single-mode regime, producing radiation in the THz range. We present measurements showing the emission of a narrowly-peaked spectrum from a fused silica tube 1 centimeter long with sub-millimeter transverse dimensions. We discuss the agreement of this data with theoretical and computational predictions, as well as possibilities for future study and application.

• L.S. Shao, D.B. Cline, X.P. Ding
  UCLA, Los Angeles, California
• K. Kusche, J.H. Park, I. Pogorelsky, V. Yakimenko
  BNL, Upton, Long Island, New York

The novel and revolutionary concept of VLA proof of principle is described in this paper. The simulation with the current BNL-ATF parameter shows that electron beam can get net energy from intense laser beam. The initial 20 MeV electron beam with energy spread of 0.001 can get hundreds of keV energy gain with energy spread of 0.010 by interacting with a laser a0=1. BNL-ATF's spectrometer can tell 0.0001 accuracy of energy spread and distinguish 0.001 accuracy energy spread. The proposal has been approved by BNL-ATF and the experiment for this proof of principle is going to be scheduled.

• R.P. Walker
  Diamond, Oxfordshire

Diamond Light Source, the UK's 3rd generation synchrotron light facility, became operational in 2007. We report here on a number of important recent developments, aimed at increasing its operational performance. In particular, we present our initial experience with regular top-up injection, which began at the end of October 2008, including its reliability and effect on beam stability. We also discuss the issues that have been faced in increasing the beam current to its design value of 300 mA. Diamond currently operates with 10 in-vacuum undulators with a specified initial minimum operating gap of 7 mm. We report on our efforts to understand and control the distribution of beam losses in the ring, in order to allow operation with gaps as small as the target value of 5 mm.

On behalf of the Diamond Machine Staff

Slides

• V.D. Shiltsev, G.F. Kuznetsov, A. Valishev
  Fermilab, Batavia
• V. Kamerdzhiev
  FZJ, Jülich
• A.L. Romanov
  BINP SB RAS, Novosibirsk

We report preliminary results of experimental studies of "electron columns" in the Tevatron and in a specialized test setup. In the Tebvatron, 150 GeV beam of protons ionized residual gas and ionization electrons are stored in an electrostatic trap immersed into strong longitudinal magnetic field. Shifts of proton betatron frequencies are reported. In the test set, we observe effects pointing to accumulation and escape of ionization electrons.

• Y. Giboudot, A. Khan
  Brunel University, Middlesex
• T.R. Edgecock
  STFC/RAL, Chilton, Didcot, Oxon
• A. Wolski
  The University of Liverpool, Liverpool

The unconventional size and the possibility of transverse displacement of the magnets in the EMMA non-scaling FFAG motivates a careful study of particle behavior within the EMMA ring. The magnetic field map of the doublet cell is computed using a Finite Element Method solver; particle motion through the field can then be found by numerical integration, using (for example) OPERA, or ZGOUBI. However, by obtaining an analytical description of the magnetic field (by fitting a Fourier-Bessel series to the numerical data) and using a differential algebra code, such as COSY, to integrate the equations of motion, it is possible to produce a dynamical map in Taylor form. This has the advantage that, after once computing the dynamical map, multi-turn tracking is far more efficient than repeatedly performing numerical integrations. Also, the dynamical map is smaller (in terms of computer memory) than the full magnetic field map; this allows different configurations of the lattice, in terms of magnet positions, to be represented very easily using a set of dynamical maps, with interpolation between the coefficients in different maps*.

*yoel.giboudot@stfc.ac.uk

• N. Wang, Y.D. Liu, Q. Qin
  IHEP Beijing, Beijing

The electron proton (e-p) instability has been observed in many proton accelerators. It will induce transverse beam size blow up, cause beam loss and restrict the machine performance. A simulation code is developed to study the electron proton instability in the China Spallation Neutron Source (CSNS) ring. The results of numerical simulation of the electron cloud formation and the electron proton instability are presented.

• U. Iriso
  CELLS-ALBA Synchrotron, Cerdanyola del Vallès
• S. Casalbuoni
  FZK, Karlsruhe
• G. Rumolo, F. Zimmermann
  CERN, Geneva

One of the key issues for the developments of superconducting insertion devices is the understanding of the beam heat load in the vacuum chamber. The beam heat load observed in the superconducting cold bore undulator installed in the ANKA storage ring is higher than the one predicted by the synchrotron radiation and resistive wall heating. A non linear increase of the dynamic pressure with the beam current is also observed in the cold bore. In order to investigate whether the nature of these effects is due to an electron cloud formation, we have performed several simulations using the ECLOUD code.

• E.S. Fischer, A. Mierau, P. Schnizer
  GSI, Darmstadt
• P.G. Akishin
  JINR, Dubna, Moscow Region
• R.V. Kurnyshov
  Electroplant, Moscow
• B. Schnizer
  TUG/ITP, Graz
• P.A. Shcherbakov
  IHEP Protvino, Protvino, Moscow Region

The first full size superconducting dipole magnets for the SIS 100 Tm synchrotron were built and tested. The achieved magnetic field has been measured with a rotating coil probe. An intensive Finite Element R&D, necessitated by the used superconducting cable as well as by the complex mechanical coil and yoke structure, allows calculating the field with high accuracy. Elliptic multipoles were used to describe the field within the whole aperture of the vacuum chamber. As the final design for the SIS 100 dipoles is curved, we developed toroidal multipoles describing the field within a curved magnet, and enabling us to interpret the measurement of a rotating coil probe within such magnets. We describe the performance of the magnetic measurement system, present the measured field properties and compare them to the calculated ones.

• A.V. Tsakanian
  Uni HH, Hamburg
• M. Dohlus, I. Zagorodnov
  DESY, Hamburg

Based on TE/TM splitting algorithm a new (longitudinally) dispersion-free numerical scheme is developed to evaluate the wake fields in structures with finite wall conductivity. The impedance boundary condition in this scheme is modeled by the one dimensional wire connected to boundary cells. A good agreement of the numerical simulations with the analytical results is obtained. The developed code allows to calculate multipole wake potentials of arbitrary shaped geometries with walls of finite high conductivity.

• H. Hahn
  BNL, Upton, Long Island, New York

Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

Continuing interest in computing the coupling impedance of cylindrical multi-layer beam tubes led to several recent publications. A novel matrix method is here presented in which radial wave propagation is treated in analogy to longitudinal transmission lines. Starting from the Maxwell equations the solutions for monopole and dipole electromagnetic fields are in each layer described respectively by a 2×2 and 4×4 matrix. Assuming isotropic material properties within one layer, the radially transverse field components at the inner boundary of a layer are uniquely determined by matrix transfer of the field components at its outer boundary. By imposing power flow constraints on the matrix, field matching between layers is enforced and replaced by matrix multiplication. The wall impedance is found as eigen solution to the scalar Helmholtz equation with the additional boundary condition that the longitudinal magnetic field vanishes at the inner beam tube wall. The matrix method is demonstrated via the example of the longitudinal impedance of a multi-layer HOM absorber, involving a ceramic tube with metal coating and an external ferrite layer.

• B. Podobedov, L. Ecker, D.A. Harder, G. Rakowsky
  BNL, Upton, Long Island, New York

We investigate AC response of accelerator vacuum chambers to external magnetic field, when the wall thickness is comparable or greater than the skin depth. Good agreement was established between experimental measurements, analytical modeling, and ANSYS simulations. Based on the results we suggest a transfer function model for electrically thick vacuum chambers with arbitrary transverse cross-section.

• G.V. Stupakov
  SLAC, Menlo Park, California
• I.A. Kotelnikov
  BINP SB RAS, Novosibirsk

Funding: Work supported by US DOE contracts DE-AC03-76SF00515

We study the impedance due to coherent synchrotron radiation (CSR) generated by a short bunch of charged particles passing through a bend magnet of finite length in a vacuum chamber of a given cross section. Our method represents a further development of the previous papers*. In this method we decompose the electromagnetic field of the beam into the eigenmodes of the toroidal chamber. We derive a system of equations for the expansion coefficients in the series, and develop a numerical algorithm for practical calculations. We illustrate our general method by calculating the CSR impedance of a beam moving in a vacuum chamber of rectangular cross section.

*G. V. Stupakov and I. A. Kotelnikov, PRST-AB 6, 034401 (2003); T. Agoh, K.Yokoya, PRST-AB, 7, 054403 (2004)

• S.P. Weathersby, A. Novokhatski, M.K. Sullivan
  SLAC, Menlo Park, California

Funding: Work supported by Department of Energy Contract DE-AC02-76SF00515

Synchrotron radiation is the main source of vacuum chamber heating in the PEP-II storage ring collider. This heating is reduced substantially as lattice energy is lowered. Energy scans over Υ energy states were performed by varying the high energy ring (HER) lattice energy at constant gap voltage and frequency. We observed unexpected temperature rise at particular locations when HER lattice energy was lowered from 8.6 GeV (Υ(3S)) to 8.0 GeV (Υ(2S)) while most other temperatures decreased. Bunch length measurements reveal a shorter bunch at the lower energy. The shortened bunch overheated a beam position monitoring electrode causing a vacuum breach. We explain the unexpected heating as a consequence of increased higher order mode (HOM) power generated by a shortened bunch. In this case, temperature rise helps to identify HOM sources and HOM sensitive vacuum chamber elements. Reduction of gap voltage helps to reduce this unexpected heating.

• L. Xiao, C.-K. Ng, J.C. Smith
  SLAC, Menlo Park, California
• F. Caspers
  CERN, Geneva

Funding: This work was supported by DOE Contract No. DE-AC02-76SF00515 and used resources of NERSC supported by DOE Contract No. DE-AC02-05CH11231, and of NCCS supported by DOE Contract No. DE-AC05-00OR22725.

A rotatable collimator is proposed for the LHC phase II collimation upgrade. When the beam crosses the collimator, trapped modes will be excited that result in beam energy loss and collimator power dissipation. Some of the trapped modes can also generate transverse kick on the beam and affect the beam operation. In this paper the parallel eigensolver code Omega3P is used to search for all the trapped modes below 2GHz in the collimator, including longitudinal modes and transverse modes. The loss factors and kick factors of the trapped modes are calculated as function of the jaw positions. The amplitude ratio between transverse and longitudinal trapped mode intensity can be used as a direct measure of the position of the beam. We present simulation results and discuss the results.

• L. Haenichen, W.F.O. Müller, T. Weiland
  TEMF, TU Darmstadt, Darmstadt
• A.M. Al-Khateeb, O. Boine-Frankenheim
  GSI, Darmstadt

Funding: This work is supported by the GSI.

Beam coupling impedances have been identified as an appropriate quantity to describe collective instabilities caused through beam-induced fields in heavy ion synchrotron accelerators such as the SIS-18 at the planned SIS-100 at the GSI facility. The impedance contributions caused by the multiple types of beamline components need to be determined to serve as input condition for later stability studies. This paper will present an approach exploiting the abilities of commercial FDTD wake codes such as CST PARTICLE STUDIO® for a benchmark problem with cylindrical geometry. Since exact analytical formulae are available, the obtained numerical results will be compared. Special attention is paid towards the representation of the particle beam as the source of the EM fields and conductive losses.

• K. Tian, G. Cheng, F. Marhauser, H. Wang
  JLAB, Newport News, Virginia
• C.D. Zhou
  Tech-X, Boulder, Colorado

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.

In this paper, we present benchmarking results for high-class 3D electromagnetic (EM) codes in designing RF cavities today. These codes include Omega3P [1], VORPAL [2], CST Microwave Studio [3], Ansoft HFSS [4], and ANSYS [5]. Two spherical cavities are selected as the benchmark models. We have compared not only the accuracy of resonant frequencies, but also that of surface EM fields, which are critical for superconducting RF cavities. By removing degenerated modes, we calculate all the resonant modes up to 10 GHz with similar mesh densities, so that the geometry approximation and field interpolation error related to the wavelength can be observed.

• S.R. Marques, O.R. Bagnato, R.H.A. Farias, F. R. Francisco, R.T. Neuenschwander, F. Rodrigues, A.L. Rosa, R.M. Seraphim, P.F. Tavares, M.M. Xavier
  LNLS, Campinas

We describe the development of a new button-type beam position monitor (BPM) for the Brazilian Synchrotron Light Source (LNLS) electron storage ring. One third of the storage ring stripline BPMs were replaced whit this new model, which counts on bellows, temperature stabilization and new support stands in order achieve improved mechanical stability. Finally, in-vacuum heat absorbers were installed at the upstream vacuum tubes of the bending magnets to minimize the vacuum chamber motion due to the high thermal load. We also present performance results.

• I. Pinayev, A. Blednykh
  BNL, Upton, Long Island, New York

Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-98CH10886.

With growth of circulating current in the storage rings the heating of the beam position monitor (BPM) buttons due to the induced trapped modes is drastically increasing. Excessive heating can lead to the errors in the measuring of beam position or even catastrophic failures of pick-up assembly. In this paper we present calculations of heat generated in the button for different geometries and materials. The obtained results are used for the optimization of the BPM design for the NSLS-II project.

• I. Pinayev, B.N. Kosciuk, O. Singh
  BNL, Upton, Long Island, New York

Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-98CH10886.

The NSLS-II Light Source being built at Brookhaven National Laboratory is expected to provide very small emittances and electron beam sizes. High resolution imaging systems are required in order to provide robust measurements. The pinhole cameras will utilize 5-fold magnification with a pinhole placed inside a crotch absorber. The pinhole is protected from high power synchrotron radiation with a filter made of refractory metal. In this paper we provide resolution analyses, heat load calculations, and optimization of NSLS-II pinhole cameras including beamline design.

• A. Zelenski, G. Atoian, A. Bazilevsky, G. Bunce, R. Connolly, D.M. Gassner, R.L. Gill, H. Huang, G.J. Mahler, Y. Makdisi, B. Morozov, S. Nemesure, T. Russo, M. Sivertz, D. Steski, S. Tepikian, R.J. Todd, K. Yip
  BNL, Upton, Long Island, New York

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

The proton polarization measurements in AGS and RHIC are based on proton-carbon and proton-proton elastic scattering in the Coulomb Nuclear Interference region. Polarimeter operation in the scanning mode gives polarization profiles and beam intensity profile measurements. This polarimeter is an ideal wire-scanner due to: extremely good signal/noise ratio and high counting rate, which allows accurate bunch by bunch emittance measurements during 100 ms time of the beam crossing. The measurements of the beam emittance in both vertical and horizontal planes will be possible after polarimeter upgrade for the 2009 polarized run. Two new vacuum chambers and two target motion mechanisms and detectors assembly will be installed in each ring. One polarimeter can be used for the vertical polarization and intensity profile measurements and the second can be used for the horizontal profile measurements. The absolute accuracy limitations and cross-calibration of different techniques will be also discussed.

• J.P. Alexander, C.J. Conolly, E. Fontes, W.H. Hopkins, B. Kreis, H. Liu, A. Lyndaker, M.A. Palmer, D.P. Peterson, P. Revesz, J.J. Savino, R.D. Seeley
  CLASSE, Ithaca, New York
• J.W. Flanagan
  KEK, Ibaraki

Funding: NSF

We report on the performance goals and design of the CESRTA x-ray beam size monitor (xBSM). The xBSM resolution must be sufficient to measure vertical beam sizes under 20um. The xBSM images 2–4keV synchrotron radiation photons onto one-dimensional photodiode array. Instrumentation in the dedicated x-ray beam line includes upstream interchangeable optics elements (slits, coded apertures, and Fresnel zone plates), a monochrometer and the InGaAs photodiode detector. To provide sufficient x-ray flux in 2 GeV operation, the beam line is evacuated, with only a thin diamond window isolating the detector vacuum from the damping ring. The readout is a beam-synchronized FADC that is sufficient to measure consecutive bunches independently in a 4ns bunch spacing configuration.

• Y. Li, M.G. Billing, S. Greenwald, T.I. O'Connell, M.A. Palmer, J.P. Sikora, E.N. Smith, K.W. Smolenski
  CLASSE, Ithaca, New York
• J.N. Corlett, R. Kraft, D.V. Munson, D.W. Plate, A.W. Rawlins
  LBNL, Berkeley, California
• K. Kanazawa, Y. Suetsugu
  KEK, Ibaraki
• M.T.F. Pivi
  SLAC, Menlo Park, California

Funding: Work supported by the National Science Foundation, the US Department of Energy, and the Japan/US Cooperation Program

Wiggler magnets are one of the key components in the ILC Damping Ring. It is critical to the ILCDR GDE to understand electron cloud (EC) growth and patterns, and to develop EC suppression techniques in the wiggler beampipes. The CESR-c superconducting wigglers, closely matching the parameters of the ILCDR wigglers, serve as unique testing vehicles. As part of the CesrTA project, we replaced the copper beampipes of two SCWs with EC diagnostic beampipes, where one of the beampipes is uncoated and the second is coated with a thin TiN film. Each of the EC diagnostic beampipes is equipped with three retarding field analyzers (RFAs) at strategic longitudinal locations in the wiggler field. Each of the RFAs has 12-fold segmentation to measure the horizontal EC density distribution. To maintain sufficient vertical beam aperture and to fit within the SCW warm bore, a thin style of RFA (with a thickness of 2.5 mm) has been developed and deployed. These SCWs with RFA-equipped beampipe have been installed and successfully operated in the re-configured CesrTA vacuum system. This paper describes the design and the construction of the RFA-equipped SCW beampipes and operational experience.

• M.A. Palmer, M.G. Billing, J.R. Calvey, G.W. Codner, S. Greenwald, Y. Li, X. Liu, J.A. Livezey, R.E. Meller, R.M. Schwartz, J.P. Sikora, C.R. Strohman, W.S. Whitney, T. Wilksen
  CLASSE, Ithaca, New York

Funding: Support provided by the US National Science Foundation and the US Department of Energy.

A central component of the operation of the Cornell Electron Storage Ring as a Test Accelerator (CesrTA) for ILC Damping Rings R&D is the characterization of electron cloud growth in each of the principal vacuum chamber types in use in the storage ring. In order to facilitate measurements in chambers with tightly constrained external apertures, retarding field analyzers have been developed that can be deployed in regions with as little as 3mm of available aperture. We report on the design, fabrication, characterization and operation of devices that are presently deployed in CESR drift, dipole, and wiggler chambers.

• G. Kotzian, F. Caspers, S. Federmann, W. Höfle
  CERN, Geneva
• R. De Maria
  BNL, Upton, Long Island, New York
• G. Kotzian
  Graz University of Technology (TUG), Signal Processing and Speech Communication Laboratory (SPSC), Graz

In particle accelerators coaxial cables are commonly used to transmit wideband beam signals covering many decades of frequencies over long distances. Those transmission lines often have a corrugated outer and/or inner conductor. This particular construction exhibits a significant amount of frequency dependent group delay variation. A comparison of simulations based on theoretical models and S11 and S21 network analyzer measurements up to 2.5 GHz is presented. It is shown how the non-linear phase response and varying group delay leads to ringing in the pulse response and subsequent distortion of signals transmitted through such coaxial transmission lines.

• L. Søby, F. Guillot-Vignot
  CERN, Geneva
• I. Podadera Aliseda
  CIEMAT, Madrid

In the framework of EUROTeV, a Precision Beam Position Monitor (PBPM) has been designed, manufactured and tested. The new PBPM, based on the inductive BPM presently used in the CERN Clic Test Facility (CTF3), aims to achieve a resolution of 100 nm and an accuracy of 10μm in a 6 mm aperture. A dedicated test bench has been designed and constructed to fully characterize and optimize the PBPM. This paper describes the final design, present the test bench results and reports on the beam tests carried out in the CERN CTF3 Linac.

• C.-Y. Tan, K.L. Duel, R.M. Zwaska
  Fermilab, Batavia

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.

We have designed a retarding field analyzer (RFA) and a rad-hard amplifier which improves the sensitivity over the present RFA installed in the Main Injector. From computer simulations and bench measurements, our RFA will have a 20% improvement in sensitivity compared to the Argonne National Laboratory (ANL) design. And when we couple our RFA to the matched rad-hard amplifier, S/N is also improved.

• J.W. Flanagan, H. Fukuma, S. Hiramatsu, H. Ikeda, K. Kanazawa, T.M. Mitsuhashi, J. Urakawa
  KEK, Ibaraki
• J.P. Alexander, W.H. Hopkins, B. Kreis, M.A. Palmer, D.P. Peterson
  CLASSE, Ithaca, New York
• G.S. Varner
  UH, Honolulu, HI

Funding: Work supported in part by the US-Japan Cooperation Program

We are working on the development of a high-speed x-ray beam profile monitor for high-resolution and fast response for beam profile measurements to be used at CesrTA and SuperKEKB*. The optics for the monitor are based on a technique borrowed from x-ray astronomy, coded-aperture imaging, which should permit broad-spectrum, low-distortion measurements to maximize the observable photon flux per bunch. Coupled with a high-speed digitizer system, the goal is to make turn-by-turn, bunch-by-bunch beam profile measurements. Following initial tests with a low-resolution mask at large beam sizes (vertical size ~200 um), a high-resolution mask has been made for use with low-emittance beams (vertical size ~10 um) at CesrTA. The first performance results of the high-resolution mask on the low-emittance CesrTA beam are presented.

*J.W. Flanagan et al., Proc. EPAC08, Genoa, {10}29 (2008).

• N. Delerue, R. Bartolini, K.J. Peach, A. Reichold, R. Senanayake
  JAI, Oxford
• S.I. Bajlekov, L.S. Caballero-Bendixsen, T. Ibbotson
  University of Oxford, Clarendon Laboratory, Oxford
• N. Bourgeois, P.A. Walker
  University of Oxford, Oxford
• B. Buonomo, G. Mazzitelli
  INFN/LNF, Frascati (Roma)
• G. Doucas, S.M. Hooker, P. Lau, D. Urner
  OXFORDphysics, Oxford, Oxon
• C.A. Thomas
  Diamond, Oxfordshire

Funding: John Adams Institute, University of Oxford John Fell Fund, University of Oxford

We describe a method that uses a modified pepper-pot design to measure in a single shot the emittance of electron beams with energies above 100 MeV. Our setup consists of several thin layers of tantalum with spacers in between to leave slits through which the electron beam can be sampled. We report on a measurement done using this method at the DAΦNE BTF with a 508 MeV electron beam.

• S. De Santis, J.M. Byrd
  LBNL, Berkeley, California
• M.G. Billing, J.P. Sikora
  CLASSE, Ithaca, New York

Funding: Supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

We report on the optimization of TE Wave measurements at the Cesr-TA ring at Cornell University. The CESR storage ring is currently used as a testbed for technologies to be used in the damping rings of the International Linear Collider. The TE Wave measurement method utilizes capacitive buttons (BPMs) in the ring to excite and detect a propagating electromagnetic wave corresponding to the beampipe's fundamental TE mode. The presence of low-energy electrons along the wave path changes its propagation characteristics, which can be detected by analyzing the received signal. By choosing the machine fill pattern (gaps and bunch trains length) it is possible to modulate the density of the electron cloud and derive information on its rise and fall times by observing the detected signal spectrum. The possibility of circulating both electron and positron beams in the ring enabled us to separate the contribution of primary photoelectrons, which are independent on the circulating particle nature, from the transverse resonant mechanism, which can increase the primary electron density many times over and which only takes place with a circulating positron beam.

• R.J. Abrams
  Muons, Inc, Batavia
• D. Hedin, V. Zutshi
  Northern Illinois University, DeKalb, Illinois

Funding: Supported in part by the Illinois Department of Commerce and Economic Opportunity

The multi-pixel photon counter (MPPC), or Geiger-mode avalanche photo-diode (GM-APD), also known as silicon photomultiplier (SiPM) is of great interest as a photon detector for high-energy physics scintillation counters, and other applications. In this paper we discuss some of the performance characteristics of MPPCs, and several applications, namely for muon cooling experiments, rare muon decay modes, and collider detectors. In addition we will discuss advances in signal processing electronics for MPPCs, which further enhance their use for large-scale applications.

• F. Hunte, J. Schwartz, H. Song
  NHMFL, Tallahassee, Florida
• R.P. Johnson, M. Turenne
  Muons, Inc, Batavia

Magnetic confinement fusion reactors (tokamaks) require the development of magnets capable of generating large fields under stringent structural constraints. High temperature superconducting magnets which are well suited to this application are however vulnerable to quench occurrence during operation. Temperature and strain sensors based on fiber optics are being developed as a countermeasure to this contingency. Optical fibers with Bragg gratings are amenable to embedding within superconducting magnets to monitor temperature, strain, irradiation, and to detect quench occurrence. In a length of YBCO tape where quench propagation velocities are slow, we show that it is possible to detect the event occurrence using fiber optic sensors even with a sampling rate as low as 1 Hz. This preliminary result demonstrates the feasibility of using fiber optic sensors to monitor the temperature and strain condition along the length within a coil. These sensors could be used to provide feedback to or trigger magnet protection systems. This would be an invaluable method for mitigating damage to superconducting magnets and increasing up-time for reactors.

• M. Dorf, R.C. Davidson, H. Qin, E. Startsev
  PPPL, Princeton, New Jersey

Funding: Research supported by the U.S. Department of Energy.

This paper reports on recent advances in the development of a numerical scheme for describing the quiescent loading of a quasi-equilibrium beam distribution matched to a periodic focusing lattice*. The scheme allows for matched-beam distribution formation by means of the adiabatic turn-on of the oscillating focusing field, and it is examined here for the cases of alternating-gradient quadrupole and periodic solenoidal lattices. Furthermore, various distributions are considered for the initial beam equilibrium. The self-similar evolution of the matched-beam density profile is observed for arbitrary choice of initial distribution function and lattice type. The numerical simulations are performed using the WARP particle-in-cell code.

* M.Dorf et al., Phys. Rev. ST Accel. Beams, submitted for publication(2009).

• C.H. Kuo, J. Chen, P.C. Chiu, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Wu
  NSRRC, Hsinchu

The orbit feedback system of the TLS has been deployed for a decade to stabilize electron closed orbit. As the upgrades of digital bpm electronics and switching power supply, the infrastructure of orbit feedback system has also been dramatically modified and rebuilt. The most primary works for the upgrade plan have been done including installation of new bpm and power supply since it was first proposed. After the ordered computer blade ready and the current updated rate raised from 1 kHz to 5 kHz or even 10 kHz, the system will evolve to a newly fast orbit feedback system. It is new scheduled to be commissioned in 2009 spring and can be expected to achieve a submicron stability of the electron beam at a bandwidth of at least 60 Hz.

• D.J. Martin, S. Allison, B. Scott, J.J. Sebek, T.A. Trautwein
  SLAC, Menlo Park, California

Funding: Operated by Stanford University for the U. S. Department of Energy under Contract DE-AC02-76-SF00515 and Office of Basic Energy Sciences.

The Bergoz Instrumentation New Parametric Current Transformer (NPCT) has been evaluated at the SPEAR3 synchrotron light source. The device was tested for vacuum performance and residual gas and was found suitable for installation in the storage ring. The NPCT was installed during August 2008 and has measured beam currents to 500 mA. Performance is compared to the earlier PCT design. The NPCT Sensor Head has been instrumented with thermal sensors for characterization of the internal operating temperature.

• A.V. Tyukhtin, T.Yu. Alekhina, E.G. Doil'nitsina, S.N. Galyamin
  Saint-Petersburg State University, Saint-Petersburg

Funding: Physical Faculty of St.Petersburg State University (14.10.08); SBIR DOE (DE-FG02-08ER85031)

Radiation of a charge crossing the boundary between vacuum and left-handed medium is analyzed. The medium is characterized by permittivity and permeability with frequency dispersion of “plasmatic” type. Such properties can be realized in some modern metamaterials with a relatively simple structure. Both the case of unbounded medium and the case of circular waveguide are considered. Analytical expressions for field components are obtained and algorithm of their computation is developed. The main attention is given to the analysis of radiation in vacuum region. In particular, it is shown that two types of radiation can be generated in this region. One of them is an ordinary transition radiation having relatively large magnitude. Another type of radiation can be named the “Cherenkov-transition” radiation. Conditions of generating this type of radiation are obtained. This effect and some another properties of radiation can be used for diagnostics of beams. For example, the detector with two energy thresholds can be designed.

• A.V. Tyukhtin
  Saint-Petersburg State University, Saint-Petersburg
• S.P. Antipov
  ANL, Argonne
• A. Kanareykin, P. Schoessow
  Euclid TechLabs, LLC, Solon, Ohio

Funding: SBIR DOE (DE-FG02-08ER85031); Russian Foundation for Basic Research (06-02-16442-a); Physical Faculty of St.Petersburg State University (Russia) (14.10.08)

We consider microwave Cherenkov radiation in a waveguide containing an engineered medium, and show that the properties of the radiation can be used to determine the energy of charged particle beams. These properties can form the basis of a new technique for bunch diagnostics in accelerators. We propose to use a material characterized by a diagonal permittivity tensor with components depending on frequency as in the case of a plasma but with the constant terms not equal to unity. These properties can be realized in a metamaterial with a relatively simple structure. In contrast to previous work in the present paper a vacuum channel in the waveguide is taken into account. The particle energy can be determined by measurement of mode frequencies. It is shown that a strong dependence of mode frequencies on particle energy for some predetermined narrow range can be obtained by appropriate choice of the metamaterial parameters and radius of the channel. It is also possible to obtain energy measurements over a wider range at the cost of a weaker frequency dependence.

*A.V.Tyukhtin, S.P.Antipov, A.Kanareykin, P.Schoessow, PAC07, p.4156.
**A.V.Tyukhtin, EPAC08, p.1302.
***A.V.Tyukhtin, Technical Physics Letters, v.34, p.884 (2008); v.35 (2009), in press.

• Y. Otake
  RIKEN Spring-8 Harima, Hyogo
• H. Ego, H. Tomizawa, K. Yanagida
  JASRI/SPring-8, Hyogo-ken
• A. Higashiya, S.I. Inoue, H. Maesaka, S. Matsubara, T. Ohshima, T. Shintake, M. Yabashi
  RIKEN/SPring-8, Hyogo

In XFEL/SPring-8, it is very important to generate an electron beam, having a low slice emittance of 0.7 pimm-mrad, a pulse width of 30 fs, and a peak current of 3 kA at an X ray lasing part. For tuning such beam to guarantee stable X ray laser generation, beam and laser monitors to diagnose the temporal structure of them are an indispensable function. The monitors, such as a beam position monitor (BPM), a TM11-mode rf beam deflector and a screen monitor (SCM), have been developed to satisfy the function. The BPM has a position resolution of less than 1 um. The SCM to observe the beam deflecting image has a position resolution of 2.5 um. The design of a longitudinal beam diagnosis system using the monitors showed that it can measure a temporal structure with a resolution of 0.5 fs along the beam pulse. The experiment to check feasibility of the BPM showed that it can work as a beam arrival timing monitor with a temporal resolution of 46 fs. A monitor system using an in-vacuum photo diode was also developed to measure the laser arrival timing, and showed ability to resolve a 2 ps time jitter. These temporal resolutions allow us fine beam tuning required for the XFEL.

• R. Nagaoka, L. Cassinari, J.-M. Filhol, M. Labat, M.-P. Level, C. Mariette, R. Sreedharan
  SOLEIL, Gif-sur-Yvette

Ever since the first user operation, the digital transverse bunch by bunch feedback system developed at SOLEIL has successfully been operated, achieving a stable multibunch beam at the highest intensity in the two planes at zero chromaticity with a single chain working in a diagonal mode. Since then a vertical stripline, optimised to generate large deflections to combat the strong single bunch headtail instability, was installed to construct another chain. The combined use of the two chains allowed enhancing the feedback performance. In particular, by differentiating the feedback gain between high and low intensity bunches, the system is capable of working in hybrid filling modes. In parallel, online applications were integrated into the control system to allow measuring the tunes by selectively exciting a single bunch, damping and growth rates, and analysing the bunch by bunch data in frequency or time domain for post-mortem purposes. Future plans including installation of a horizontal stripline and a noise reduction by avoiding the baseband conversion of the beam signal are also discussed.

• J. Ruan, A.H. Lumpkin, J.K. Santucci
  Fermilab, Batavia

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.

Excellent phase stability of the drive laser is a critical performance specification of photoinjectors such as Fermilab’s A0 photoinjector (A0PI). Previous efforts based on the measurement of the power spectrum of the signal of a fast photodiode illuminated by the mode locked infra-red laser pulse component indicated a phase jitter of less than 1.4 ps (technique limited). A recently procured dual-sweep plugin unit and existing Hamamatsu C5680 streak camera were used to study the phase stability of the UV laser pulse component. Initial measurements with the synchroscan vertical sweep unit locked to 81.25 MHz showed that the phase slew through the micropulse train and the phase jitter micropulse to micropulse were two key aspects that could be evaluated. The phase slew was much less than 100 fs per micropulse, and the total phase jitter (camera, trigger, and laser) was approximately 300 fs RMS for measurements of 20-micropulse trains. Data on the macropulse phase stability were also obtained. A possible upgrade to achieve better phase stability will be also discussed.

• M.A. Palmer, J.P. Alexander, M.G. Billing, J.R. Calvey, S.S. Chapman, G.W. Codner, C.J. Conolly, J.A. Crittenden, J. Dobbins, G. Dugan, E. Fontes, M.J. Forster, R.E. Gallagher, S.W. Gray, S. Greenwald, D.L. Hartill, W.H. Hopkins, J. Kandaswamy, D.L. Kreinick, Y. Li, X. Liu, J.A. Livezey, A. Lyndaker, V. Medjidzade, R.E. Meller, S.B. Peck, D.P. Peterson, M.C. Rendina, P. Revesz, D.H. Rice, N.T. Rider, D. L. Rubin, D. Sagan, J.J. Savino, R.D. Seeley, J.W. Sexton, J.P. Shanks, J.P. Sikora, K.W. Smolenski, C.R. Strohman, A.B. Temnykh, M. Tigner, S. Vishniakou, W.S. Whitney, T. Wilksen, H.A. Williams
  CLASSE, Ithaca, New York
• J.M. Byrd, C.M. Celata, J.N. Corlett, S. De Santis, M.A. Furman, A. Jackson, R. Kraft, D.V. Munson, G. Penn, D.W. Plate, A.W. Rawlins, M. Venturini, M.S. Zisman
  LBNL, Berkeley, California
• J.W. Flanagan, P. Jain, K. Kanazawa, K. Ohmi, H. Sakai, K. Shibata, Y. Suetsugu
  KEK, Ibaraki
• K.C. Harkay
  ANL, Argonne
• Y. He, M.C. Ross, C.-Y. Tan, R.M. Zwaska
  Fermilab, Batavia
• R. Holtzapple
  CalPoly, San Luis Obispo, CA
• J.K. Jones
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• D. Kharakh, M.T.F. Pivi, L. Wang
  SLAC, Menlo Park, California
• E.N. Smith
  Cornell University, Ithaca, New York
• A. Wolski
  Cockcroft Institute, Warrington, Cheshire

Funding: Support provided by the US National Science Foundation, the US Department of Energy, and the Japan/US Cooperation Program.

In March of 2008, the Cornell Electron Storage Ring (CESR) concluded twenty eight years of colliding beam operations for the CLEO high energy physics experiment. We have reconfigured CESR as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R&D. The primary goals of the CesrTA program are to achieve a beam emittance approaching that of the ILC Damping Rings with a positron beam, to investigate the interaction of the electron cloud with both low emittance positron and electron beams, to explore methods to suppress the electron cloud, and to develop suitable advanced instrumentation required for these experimental studies (in particular a fast x-ray beam size monitor capable of single pass measurements of individual bunches). We report on progress with the CESR conversion activities, the status and schedule for the experimental program, and the first experimental results that have been obtained.

Slides

• J.Z. Zhou, C. Chen, K.R. Samokhvalova
  MIT/PSFC, Cambridge, Massachusetts

Funding: This work was supported by the Department of Energy, Grant No. DE-FG02-95ER40919 and the Air Force Office of Scientific Research, Grant No. FA9550-06-1-0269.

An adiabatic warm-fluid equilibrium theory for a thermal charged-particle beam in an alternating gradient (AG) focusing field is presented. Warm-fluid equilibrium equations are solved in the paraxial approximation and the rms beam envelope equations and the self-consistent Poisson equation, governing the beam density and potential distributions, are derived. The theory predicts that the 4D rms thermal emittance of the beam is conserved, but the 2D rms thermal emittances are not constant. Although the presented rms beam envelope equations have the same form as the previously known rms beam envelope equations, the evolution of the rms emittances in the present theory is given by analytical expressions. The beam density is calculated numerically, and it does not have the simplest elliptical symmetry, but the constant density contours are ellipses whose aspect ratio decreases as the density decreases along the transverse displacement from the beam axis. For high-intensity beams, the beam density profile is flat in the center of the beam and falls off rapidly within a few Debye lengths, and the rate at which the density falls is approximately isotropic in the transverse directions.

• V. Akcelik, K. Ko, L. Lee, Z. Li, C.-K. Ng
  SLAC, Menlo Park, California
• G. Cheng, R.A. Rimmer, H. Wang
  JLAB, Newport News, Virginia

Funding: This work was supported by DOE Contract No. DE-AC02-76SF00515 and used resources of NERSC supported by DOE Contract No. DE-AC02-05CH11231, and of NCCS supported by DOE Contract No. DE-AC05-00OR22725.

SLAC has developed a multi-physics simulation code TEM3P for simulating integrated effects of electromagnetic, thermal and structural effects. TEM3P shares the same finite element infrastructure with EM finite elements codes developed at SLAC. This enables simulations within a single framework. Parallel implementation allows large scale computation, and high fidelity and high accuracy simulations can be performed in faster time. In this paper, TEM3P is used to analyze thermal loading in the coupler end-groups of the JLAB SCRF cavity. The results are benchmarked against measurements.

• K. Haghighi mood
  PPRC, Tehran
• M. Aslaninejad
  IPM, Tehran

2D potential profiles for uniformly populated discs of charged particles with circular and elliptical cross sections inside a perfectly conducting ring are simulated using the method of images. The results are compared with the problem of infinitely long linear charge distribution inside a conducting cylinder with a dependence only on the two transverse coordinates*.

*Miguel A. Furman Phys. Rev. ST Accel. Beam 10, 081001(2007)

• O.V. Sinitsyn, T.M. Antonsen, R.A. Kishek, G.S. Nusinovich
  UMD, College Park, Maryland

Funding: Office of High Energy Physics, US Department of Energy (DoE).

Multipactor (MP) may occur in many situations: one- and two-surface MP, resonant and poly-phase-MP, on the surface of metals and dielectrics etc. We consider this phenomenon in dielectric loaded accelerator (DLA) structures. The starting point for our work is experimental and theoretical studies of such structures jointly done by Argonne National Lab and Naval Research Lab*. In the theoretical model developed during those studies, the space charge field due to the accumulated charged particles is taken into account as a parameter. We offer a non-stationary 2D cylindrical model where the DC field is taken into account self-consistently. We have improved our previous model** and demonstrated that its predictions are in good agreement with the results of other studies***. We also demonstrate some recent results where the effects of axial particle motion are taken into account.

*J.G. Power et al., PRL, 92, 164801, 2004
**O.V. Sinitsyn et. al., AIP Proc. 13th Advanced Accelerator Concepts, 2008
***J.G. Power, S.H. Gold, AIP Proc.12th Advanced Accelerator Concepts, 2006

• E.R. Arab
  PBPL, Los Angeles
• G. Travish, N. Vartanian, J. Xu
  UCLA, Los Angeles, California
• R.B. Yoder
  Manhattanville College, Purchase, NY

The millimeter-scaleμAccelerator Platform (MAP)–essentially a “particle accelerator on a chip”–will ultimately allow for revolutionary medical and industrial applications due to its manageable size and reproducibility. The MAP consists of an electron source and an all-dielectric, laser powered, particle accelerator. The dielectric structure has two slab-symmetric reflecting mirrors with a vacuum gap between them. A periodic coupling mechanism allows laser power to enter transversely through one mirror. This mechanism is analogous to the slots of an optical diffraction grating, with coupling period and vacuum gap equal to the wavelength of the laser (800nm in this study). Work to date has included designing, fabricating and testing a prototype relativistic structure using a patterned gold layer. To go further, we have studied the fabrication techniques and electromagnetic designs of an all-dielectric (non-metallic) structure. Fabrication of the final structure is modeled after Vertical-Cavity Surface-Emitting Lasers (VCSEL) and Distributed Bragg Reflector (DBR) techniques. Preliminary numerical studies of the sub-relativistic structure are also presented.

• A. Blednykh, M.J. Ferreira, S. Krinsky
  BNL, Upton, Long Island, New York

Impedance of two vacuum chamber components, Bellows and BPM, is considered in some detail. In order to avoid generation of Higher-Order Modes (HOM’s) in the NSLS-II bellows, we designed a new low-impedance RF shielding consisting of 6 wide and 2 narrow metal plates without opening slots between them. The short-range wakepotential has been optimized taking into account vertical offset of RF fingers from their nominal position. The results were compared with data of bellows designed at other laboratories. Narrow-band impedance of the BPM Button has been studied. TE-modes in the BPM button were suppressed by a factor of 8 by modification of existing housings. Two new types of housings are shown. The total impedance of the NSLS-II storage ring is discussed in terms of the loss factor and the vertical kick factor for a 3mm-Gaussian bunch.

• A. Blednykh, S. Krinsky, B. Nash, L.-H. Yu
  BNL, Upton, Long Island, New York

For the NSLS-II storage ring with damping wigglers but without a Landau cavity, the low-current bunch length is 4.5mm. We have studied bunch lengthening and estimated the microwave instability threshold using the multi-particle tracking code TRANFT. An estimate of the pseudo-Green’s function for a 0.5mm driving bunch was obtained for most components of the vacuum system by using the 3D code GdfidL. With our present computer resources, certain components were too large and had too complex geometry to allow the wake for such a short bunch to be computed using GdFidL. In these cases, the actual 3D geometry was approximated by a structure having circular cross-section, and the pseudo-Green’s function was computed using the 2D code ABCI. It was found that the dominant geometric wake is due to the tapers for the in-vacuum undulators. The resistive wall wake is also important. The effect of pseudo-Green’s functions corresponding to an even shorter driving bunch (0.05mm) was investigated using the program ECHO to compute the wake of tapers with circular cross-section. Our results suggest that the microwave threshold will occur at an average single-bunch current greater than 5mA.

• E. Pozdeyev
  BNL, Upton, Long Island, New York
• F. Marti, R.C. York
  NSCL, East Lansing, Michigan
• J.A. Rodriguez
  CERN, Geneva

Studies of space charge effects in the Small Isochronous Ring (SIR) at Michigan State University revealed a fast longitudinal instability at and below the transition that could not be explained by the conventional negative mass instability. The observed beam behavior can be explained by the effect of the radial component of the coherent space charge force on the longitudinal motion. The transverse coherent space charge force effectively modifies the slip factor shifting the isochronous point and enhancing the negative mass instability. This paper presents results of numerical and experimental studies of the longitudinal beam dynamics in SIR and proposes an analytical model explaining the results.

• M. Ivanyan, V.M. Tsakanov, A. Vardanyan
  CANDLE, Yerevan
• M.M. Dehler, T. Schmidt, A. Streun
  PSI, Villigen

The longitudinal and transverse impedances of CPMU (cryogenic permanent magnet undulators) of the SLS storage ring are evaluated. The study takes into account the walls frequency dependent conductivity and the electrical and magnetic properties of the material at low temperature.

• M. Ivanyan, V.M. Tsakanov
  CANDLE, Yerevan
• M.M. Dehler
  PSI, Villigen
• A. Grigoryan
  YSU, Yerevan

The resistive longitudinal and transverse wakefields, longitudinal loss and transverse kick factors excited by the electron bunch in undulator section of the PSI-XFEL are given. The ordinary and in vacuum undulators are considered. For in vacuum undulator the modified technique for impedance calculation is developed.

• M. Korostelev, A. Wolski
  Cockcroft Institute, Warrington, Cheshire
• N.A. Collomb, J.M. Lucas
  STFC/DL, Daresbury, Warrington, Cheshire
• O.B. Malyshev
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire

Vacuum chamber transitions of the ILC damping rings associated with BPM insertions, vacuum ports, antechamber tapers etc, may make a significant contribution to the overall machine impedance. Since most transitions are not azimuthally symmetric, commercial 3D codes based on the finite element method have been used to compute their wake fields. The results for selected vacuum chamber components are presented in this paper, together with some estimates of the impact of the wake fields on the beam dynamics in the damping rings.

• J.D.A. Smith
  Cockcroft Institute, Warrington, Cheshire

The prototype collimator of the ILC is simulated, to address potential issues with trapped modes and heating. A number of codes are benchmarked, and the interplay between resistive and geometric wakefields is carefully considered.

• M.G. Billing, H.A. Williams
  CLASSE, Ithaca, New York

Wake fields arising from the discontinuities in the vacuum chamber produce energy spread. In an energy recovery linac (ERL), a spent beam is decelerated before it is dumped in order to use its energy for the acceleration of new beam. While the energy spread accumulated from wakes before deceleration does not increase during deceleration, it becomes more important relative to the beam's decreasing energy. Therefore, in an ERL, wakes can produce very significant energy spread in the beam as it is decelerated to the energy of the beam dump so that beam transport to the dump may become impractical. This effect can place a limit either on the maximum charge per bunch or on the wake field-budget for the ERL. As an example of these wake field effects, this paper discusses their impact for the present design of the Cornell ERL and estimates the effects for typical vacuum chamber components being considered.

• R. Wanzenberg
  DESY, Hamburg
• E. Métral
  CERN, Geneva

Wakefields and trapped Higher Order Modes in the CMS experimental chamber at the LHC are investigated using a geometrical model which closely reflects the presently installed vacuum chamber. The basic rf-parameters of the higher order modes (HOMs) including the frequency, loss parameter,and the Q-value are provided. To cover also transient effects the short range wakefields and the total loss parameter has been calculated, too. Most numerical calculations are performed with the computer code MAFIA. The calculations of the Modes is complemented with an analysis of the multi-bunch instabilities due to the longitudinal and dipole modes in the CMS vacuum chamber.

• E. Mahner, F. Caspers, T. Kroyer
  CERN, Geneva
• C. Dr. Wendel
  Wendel GmbH, Dillenburg

During the 2007 run with the nominal LHC proton beam, electron cloud has been clearly identified and characterized in the PS using a dedicated setup with shielded button-type pickups. Efficient electron cloud suppression could be achieved with a stainless steel stripline-type electrode biased to negative and positive voltages up to ± 1 kV. For the 2008 run, a second setup was installed in straight section 84 of the PS where the stainless steel was replaced by a stripline composed of an enamel insulator with a resistive coating. In contrast to ordinary stripline electrodes this setup presents a very low beam coupling impedance and could thus be envisaged for long sections of high-intensity machines. Here, we present first comparative measurements with this new type of enamel clearing electrode using the nominal LHC beam with 72 bunches and 25 ns bunch spacing.

• E. Métral, F. Caspers, A. Grudiev, T. Kroyer
  CERN, Geneva
• F. Roncarolo
  UMAN, Manchester
• B. Salvant
  EPFL, Lausanne
• B. Zotter
  Honorary CERN Staff Member, Grand-Saconnex

The LHC phase 2 collimation project aims at gaining a factor ten in cleaning efficiency, robustness and impedance reduction. From the impedance point of view, several ideas emerged during the last year, such as using dielectric collimators, slots or rods in copper plates, or Litz wires. The purpose of this paper is to discuss the possible choices, showing analytical estimates, electro-magnetic simulations performed using Maxwell, HFSS and GdFidL, and preliminary bench measurements. The corresponding complex tune shifts are computed for the different cases and compared on the stability diagram defined by the settings of the Landau octupoles available in the LHC at 7 TeV.

• G. Rumolo, D. Schulte
  CERN, Geneva

The specification for vacuum pressure in the CLIC electron Main Linac critically depends on the fast ion instability. In fact, the maximum tolerable pressure value in the pipe of the Main Linac is dictated by the threshold above which the fast ion instability sets in over a CLIC bunch train. Previous calculation based on ion generation from residual gas ionization alone showed that, due to the loss of the trapping along the linac caused by the beam size shrinking from acceleration, a pressure as high as 10 nTorr could be accepted, higher than the tolerable value in the long transfer line. However, since the accelerated beam becomes transversely very small, its electric field can reach values above the field ionization threshold. When this happens, the whole space region with a sufficiently high electric field gets instantly fully ionized by the first bunch and the effect on the bunch train could be severe. We have modeled field ionization in our simulation code FASTION and re-evaluated the onset of fast ion instability in the Main Linac.

• T. Demma, R. Cimino, A. Drago
  INFN/LNF, Frascati (Roma)
• S. Petracca
  U. Sannio, Benevento
• A. Stabile
  INFN-Salerno, Baronissi, Salerno

The electron cloud driven effects can limit the ability of recently build or planned accelerators to reach their design parameters. The secondary emission yield reduction (called "scrubbing") due to the fact that the electrons of the cloud hit the vacuum chamber wall, modifying its surface properties, may minimize any disturbing effects of the cloud to the beam. The dependence of "scrubbing" efficiency on beam and chamber parameters can be deduced from e-cloud simulation codes modeling the involved physics in full detail. In this communication we present a generalization of the map formalism, introduced in*,**, for the analysis of electron flux at the chamber wall with particular reference to the exploration of LHC conditioning scenarios. Simulations based on this formalism are orders of magnitude faster compared to those based on standard particle tracking codes.

*U.Iriso and S.Peggs, ”Maps for Electron Clouds”, Phys. Rev. ST-AB 8, 024403, 2005.
**T.Demma et al., ”Maps for Electron Clouds: Application To LHC”, Phys. Rev. ST-AB 10, 114401 (2007).

• A. Novokhatski
  SLAC, Menlo Park, California
• M. Zobov
  INFN/LNF, Frascati (Roma)

Funding: work supported by the Department of Energy under contract number DE-AC03-76SF00515

We give an overview of wake fields and impedances in a proposed Super B project, which is based on extremely low emittance beams colliding at a large angle with a crab waist transformation. Understanding the effect wake fields have on the beam is critical for a successful machine operation. We use our combined experience from the operation of the SLAC B-factory and DAΦNE Phi-factory to eliminate strong HOM sources and minimize the chamber impedance in the Super B design. Based on a detailed study of the wake fields in this design we have developed a quasi-Green’s function for the entire ring that is used to study bunch lengthening and beam stability. In particular, we check the stability threshold using numerical solutions of the Fokker-Plank equation. We also make a comparison of numerical simulations with the bunch lengthening data in the B- factory.

• A. Novokhatski, J. Seeman, M.K. Sullivan, U. Wienands
  SLAC, Menlo Park, California

Funding: work supported by the Department of Energy under contract number DE-AC03-76SF00515

We present the history and analysis of different wake field effects throughout the operational life of the PEP-II SLAC B-factory. Although the impedance of the high and low energy rings is small, the high current intense beams generated a lot of power. These wake field effects are: heating and damage of vacuum beam chamber elements like RF seals, vacuum valves , shielded bellows, BPM buttons and ceramic tiles; vacuum spikes, vacuum instabilities and high detector background; beam longitudinal and transverse instabilities. We also discuss the methods used to eliminate these effects. Results of this analysis and the PEP-II experience may be very useful in the design of new storage rings and light sources.

• D.J. Scott, S.P. Jamison
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• P.J. Phillips
  University of Dundee, Nethergate, Dundee, Scotland
• I.R.R. Shinton
  UMAN, Manchester

Accurate determination of the wakefield effects for high intensity, short electron bunches is an area of active research in accelerator design. Of particular interest is the resistive wall wakefield which depends upon the complex conductivity of the vacuum vessel. This conductivity depends on factors such as the frequency of the applied field, the temperature of the vessel and the level of impurities in the vessel material and so is generally difficult to characterise for real vessels. We present an experiment for determining the complex conductivity properties of a cylindrical vessel at frequencies in the THz regime, through the sub-picosecond time-resolved measurement of pulsed THz radiation transmitted through the structure. These results are compared to theoretical calculations.

• J.G. Lopes, F.A. Alegria
  IST, Lisboa
• L.M. Redondo
  ISEL, Lisboa

The Ion Beam Laboratory of the Technological Nuclear Institute (ITN) in Lisbon has a particle accelerator based on the Van de Graaff machine which is used for research in the area of material characterization. The Van de Graaff particle accelerator* in the ITN is an horizontal electrostatic accelerator capable of producing Helium and Hydrogen ion beams with energies up to 3 MeV. The developed system comprises the accelerator turn-on and turn-off procedures during a normal run, which includes the set of terminal voltage, ion source, beam focusing and control of ion beam current and energy during operation. In addition, the computer monitors the vacuum and is able to make a detail register of the most important events during a normal run, allowing the use of the machine by less qualified technicians in safe conditions. The data acquisition system consists in PC, a data acquisition I/O board compose by with two multifunction input/output boards from National Instruments and five electronic modules. The computer control system uses a LabVIEW synoptic for interaction with the operator and an I/O board that interfaces the computer and the accelerator system.

*Rosenblatt, J. “Particle Acceleration”. London, Methuen and Co LTD., 1968.

• U. Wienands, B. Allen, W.S. Colocho, R.A. Erickson, M. Stanek
  SLAC, Menlo Park, California

Funding: Work supported by US DOE

For LCLS, an uptime of 95% of the scheduled beam time is aimed for. This is a challenging goal for a linac-driven facility, exceeding typical up time during PEP-II running by a significant amount. During the 2008 and the 2009 LCLS beam-commissioninng runs we have been gathering and analysing statistics to identify the worst offenders as far as downtime is concerned. In 2008, an overall hardware uptime of 90% was achieved, indicating the need to decrease our downtime by a factor of two. One approach to focus the effort has been to identify those faults that cause the worst performance for a system in a given time period and focus on these. Another one is to compare our MTTR performance with that of other facilities thus identifying where our processes might be improved. In this paper we will show how we track our performance and examples of the benefit of addressing identified reliability issues.

• M.W. Froese, K. Blaum, J.R. Crespo López-Urrutia, F. Fellenberger, M. Grieser, D. Kaiser, M. Lange, F. Laux, S. Menk, D. Orlov, R. Repnow, C.D. Schröter, D. Schwalm, A. Shornikov, T. Sieber, J. Ullrich, J. Varju, A. Wolf, R. von Hahn
  MPI-K, Heidelberg
• O. Heber, M.L. Rappaport, Y. Toker, D. Zajfman
  Weizmann Institute of Science, Physics, Rehovot

Funding: This work is supported by the Max Planck Society.

An electrostatic Cryogenic Storage Ring (CSR) is currently being built in Heidelberg, Germany. The current status and final design of this ring, with a focus on the precision chamber suspension, optimized 2K chamber cooling, and the cryogenic pumping down to extremely low pressures will be presented. This ring will allow long storage times of ion beams with energies in the range of keV per charge for highly charged ions and polyatomic molecules. Combined with vacuum chamber temperatures approaching 2K, infrared-active molecular ions will be radiatively cooled to their rotational ground states. Many aspects of this concept were experimentally tested with a cryogenic trap for fast ion beams (CTF), which has already demonstrated the storage of fast ion beams in a large cryogenic device. An upcoming test will investigate the effect of pre-baking the cryogenic vacuum chambers to 600K on the cryogenic vacuum and the ion beam storage.

• P.N. Ostroumov, J.D. Fuerst, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.W.T. MacDonald, R.C. Pardo, S.I. Sharamentov, K.W. Shepard, G.P. Zinkann
  ANL, Argonne

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.

An energy upgrade project of the ATLAS heavy ion linac at ANL includes a new cryomodule containing seven {10}9 MHz β=0.15 quarter-wave superconducting cavities to provide an additional 15 MV voltage to the existing linac. Several new features have been incorporated into both the cavity and cryomodule design. For example, the primary feature of the cryomodule is a separation of the cavity vacuum space from the insulating vacuum. The cavities are designed in order to cancel the beam steering effect due to the RF field. The cryomodule was designed and built as a prototype for the driver linac of the Facility for Rare Isotope Beams (FRIB). Similar design can be effectively used in the SC proton linac for the Project X at FNAL. Currently, we are working on cryomodule assembly and final preparation of cryogenics, RF, vacuum and other subsystems for off-line tests. The initial commissioning results will be reported.

• C.-Y. Tan, D.S. Bollinger, C.W. Schmidt
  Fermilab, Batavia

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.

The present FNAL Linac H^- injector has been operational since 1978 and consists of a magnetron H^- source and a 750-keV Cockcroft-Walton Accelerator. The proposed upgrade to this injector is to replace the present magnetron source having a rectangular aperture with a circular aperture, and to replace the Cockcroft-Walton with a 200-MHz RFQ. Operational experience at other laboratories has shown that the upgraded source and RFQ will be more reliable and require less manpower than the present system.

• A. Pepato, F. Scantamburlo
  INFN- Sez. di Padova, Padova
• M. Comunian, A. Palmieri, A. Pisent, C. Roncolato
  INFN/LNL, Legnaro (PD)
• E. Fagotti
  Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova

The IFMIF-EVEDA RFQ is a 9.8 m long cavity, whose working frequency is equal to 175 MHz. In the base line design the accelerator tank is composed of 9 modules flanged together and a pattern of lateral CF100 flanges allows to host the dummy tuners and the couplers, and a pattern of CF 150 flanges the apertures for vacuum pumping manifolds as well. The construction procedure of each module foresees the horizontal brazing of four half –module length electrodes and then the vertical brazing of two brazed assembly. The progresses in the design and engineering phase, as well the description of all the fabrication phases are reported.

• D. Giove
  Istituto Nazionale di Fisica Nucleare, Milano
• C. De Martinis
  Universita' degli Studi di Milano & INFN, Segrate
• M.R. Masullo, V.G. Vaccaro
  Naples University Federico II and INFN, Napoli
• S.J. Mathot
  CERN, Geneva
• A.C. Rainò
  Bari University, Science Faculty, Bari
• R.J. Rush
  e2v, Chelmsford, Essex
• V. Variale
  INFN-Bari, Bari

ACLIP is a proton 3 GHz SCL linac designed as a booster for a 30 MeV commercial cyclotron . The final energy is 60 MeV well suitable for the therapy of ocular tumours or for further acceleration (up to 230 MeV) by a second linac in order to treat deep seated tumours. ACLIP has a 5 modules structure coupled together. The first one (able to accelerate proton from 30 to 35 MeV) has been completely assembled. High power tests are in progress at e2v in Chelmsford, UK, where the possibility of using magnetrons as the source of RF power is under investigation. Acceleration tests are foreseen for Spring 2009. In this paper we will review the main features of the linac and discuss the results of RF measurements, high power RF tests and possibly acceleration tests.

• T.J. Zhang, Y.J. Bi, F.P. Guan, X.L. Jia, S.M. Wei, J.Q. Zhong
  CIAE, Beijing
• G. Dutto, G.H. Mackenzie, L.W. Root
  TRIUMF, Vancouver
• J.Z. Wang
  Department of Physics, Central China Normal University, Wuhan

There is increasing interest in high current compact H^- cyclotrons for RIB, isotope production or as injectors for sub-critical reactor testing facilities. For compact cyclotrons, a practical limit on the output energy, to prevent significant Lorentz stripping and resulting activation, is ~100 MeV. Vacuum dissociation is another critical problem, because a compact structure and small parts inside the tank make high vacuum challenging. This paper describes how Lorentz stripping and vacuum dissociation were calculated for our “CYCIAE-100” under construction. In order to take into account non uniform magnetic fields and vacuum, losses were calculated by numerically integrating loss equations along tracked orbits, as these were being calculated by the beam dynamics code. To verify the code, losses derived with field and vacuum data from the TRIUMF 500 MeV cyclotron were compared with measurements. For the CYCIAE-100 cyclotron we predict that electromagnetic losses will account for less then 0.3% of total beam, vacuum losses for less than 0.58%, with peak magnetic fields up to 1.35T and average vacuum up to 5·10^-8 Torr.