• A.K. Upadhyay, P. Jha
  Lucknow University, Lucknow
• S. Krishnagopal
  BARC, Mumbai
• S.A. Samant, D. Sarkar
  CBS, Mumbai

Nonlinear, high-amplitude plasma waves are excited in the wake of an intense laser pulse propagating in a cold plasma, providing acceleration gradients up to GeV/m. Linear analytic analyses have shown that the wakefield amplitude is optimal for a certain ratio of the pulse length and plasma wavelength*,**. Here we present results of simulation studies to optimize the nonlinear wakefield amplitudes. Variation in the laser pulse length is considered for maximizing amplitudes of wakefields generated by half-sine and Gaussian pulse profiles. Further, the advantages of using a transversely inhomogeneous plasma for the generation of the nonlinear wakefields are studied and compared with the homogeneous case.

* E. Esarey, P. Sprengle, J. Krall and A. Ting, IEEE Trans. Palsma Sci. 24, 252 (1996)
** L. M. Gorbunov and V. I. Kirsanov, Zh. Eksp. Teor. Fiz. 93, 509 (1987), Sov. Phys. JETP, 46, 290 (1988).

• S. Krishnagopal
  BARC, Mumbai
• P. Jha, A.K. Upadhyay
  Lucknow University, Lucknow
• S.A. Samant, D. Sarkar
  CBS, Mumbai

We study electron acceleration by two laser pulses co-propagating one behind the other in a homogeneous plasma. We show, using one-dimensional simulations, that the wake amplitude can be amplified or diminished depending on the time delay between the two lasers, in agreement with linear analytic theory. We extend the study to the bubble regime using two-dimensional simulations. We find that the one-dimensional optimization holds in two dimensions also. Trapping and acceleration of quasi-monoenergetic electrons (up to around 300 MeV) is found in the bucket behind the second laser, even for low intensities, where there is no trapping with a single laser. Thus, this scheme could be very useful for achieving a desired accelerated energy with less intense lasers, or, equivalently, increasing the accelerated energy for a given laser intensity.

* G. Raj, A. K. Upadhyay, R. K. Mishra and P. Jha, Phys. Rev. ST Accel. and Beams 11, 071301 (2008).

• M. Mori, S.V. Bulanov, Y. Hayashi, K. Kawase, K. Kondo, A.S. Pirozhkov, A. Sugiyama
  JAEA, Ibaraki-ken
• M. Kando
  JAEA APRC, Ibaraki-ken
• H. Kotaki, K. Ogura
  JAEA/Kansai, Kyoto
• H. Nishimura
  ILE Osaka, Suita

The pointing stability and the divergence of a quasi-monoenergetic electron bunch generated in a self-injected laser-plasma acceleration regime were investigated. Gas-jet targets have been irradiated with focused 40 fs laser pulses at the 4-TW peak power. A pointing stability of 2.4 mrad root-mean-square (RMS) and a beam divergence of 10.6 mrad (RMS) were obtained using argon gas-jet target for 50 sequential shots, while these values were about three times smaller than at the optimum condition using helium. In particular, the peak electron energy was 9 MeV using argon, which is almost three times lower than that using helium. This result implies that the formation of the wake-field is different between argon and helium, and it plays an important role in the generation of a electron bunch. This stabilization scheme is available for another gas material such as nitrogen. At nitrogen gas-jet target, the pointing stability is more improved to 1.4 times smaller (1.7 mrad (RMS)) than that in argon gas-jet target and the peak energy is increased to grater than 40 MeV. These results prove that this method not only stabilize the e-beam but also allows controlling the electron energy.

• K. Koyama
  University of Tokyo, Tokyo
• A. Maekawa, H. Masuda, M. Uesaka
  The University of Tokyo, Nuclear Professional School, Ibaraki-ken
• Y. Oishi
  Central Research Institute of Electric Power Industry, Yokosuka-shi, Kanagawa

We are studying the artificial injection of initial electrons into the wakefield for producing stable electron bunch (the charge is 100 pC, the energy stability is better than a few per cent). The objective of our research is to produce 100-keV class monochromatic X-ray pulses for measuring concentrations of nuclear materials in a reprocessing plant. A K-edge densitometry using monochromatic hard x-ray beams is one of the effective technique to measure concentrations of nuclear materials in a reprocessing solutions. An inverse Compton scattering process between an IR-laser beam of 800 nm and high-energy electron bunch of above 80 MeV makes it possible to deliver tunable monochromatic x-rays near K-absorption edges of nuclear materials of 115-129 keV. In order to use in a reprocessing plant, the equipment for the K-edge densitometry must be smaller than a compact car. The only solution to realize the compact system is to use a laser wakefield accelerator instead of a radio frequency linac. An ultra-short ten-TW laser pulse focused on a supersonic jet makes it possible to accelerate electrons up to 100 MeV in a plasma length of 2.5 mm.

• J. Kim, G. Kim, J. Kim, S.H. Yoo
  KERI, Changwon

Using the nonlinear interaction between the high power laser and the plasma, we can generate strong acceleration field, called the laser wake field acceleration. The plasma density is very crucial to generate high energy electron. In this work, we studied the effect of the plasma density structure on the accelerated electron energy. We used 20 TW, 40 fs laser system to generate the plasma wakefield. A gas jet was used as a target. The plasma density was controlled by the back pressure of the gas nozzle and measured by the interferometer. The accelerated electron energy was measured using the electron energy spectrometer with 0.5 T magnet. The bunch charge was measured integrated charge transformer (ICT). When the plasma density is uniform, 2×10¹⁹ cm^-3 we can generate 200 MeV electron beam with bunch charge 33 pC. The electron beam divergence was less than 5 degree. If there exists the downward density tramp, the electron energy is only 50 MeV. The PIC simulation also indicates that if there is density ramp structure, the electron is not accelerated well. In this presentation, the overall experimental and simulation results are presented.

• H. Suk, D. Jang, D. Jang, M. Kim, S. Oh
  APRI-GIST, Gwangju

In recent years, the laser-driven plasma wakefield acceleration has attracted much attention as it has a much higher acceleration gradient (>100 GeV/m) compared with the RF-based conventional accelerators. In the past, the supersonic gas jet method for plasma wakefield acceleration was widely used, but this method has a limitation in acceleration distance and energy because the focused laser beam is diffracted severely over a very short distance (~ a few mm range). To avoid the diffraction problem, a capillary plasma source can be used, where a high power laser beam can be guided over a long distance (~ a few cm range) by a parabolic plasma density profile in the capillary plasma channel. We have developed a gas-filled capillary plasma source for generation of GeV-level electron beams in collaboration with the University of Oxford team. In this presentation, the detailed test results and the near-future experimental plan for GeV-level e-beam generation are shown.

• K.M. Krushelnick, V. Chvykov, F.J. Dollar, G. Kalintchenko, A. Maksimchuk, T. Matsuoka, C.S. McGuffey, W. Schumaker, A.G.R. Thomas, V. Yanovsky
  University of Michigan, FOCUS Center for Ultrafast Optical Science, Ann Arbor, Michigan

Recent experimental results will be discussed with regard to the use of the 300 TW, 30 fsec HERCULES laser system at the Center for Ultrafast Optical Science at Michigan to generate GeV range electron beams using Laser Wakefield Acceleration (LWFA). The electron beam quality is shown to be improved substantially using gas mixtures- causing an increase in beam charge and a decrease in emittance. The dynamics of the acceleration process are also determined by measurements of spatially resolved scattered laser radiation and the use of femtosecond optical probing techniques.

• B.M. Cowan, M.C. Lin, B.T. Schwartz
  Tech-X, Boulder, Colorado
• R.L. Byer, C. McGuinness
  Stanford University, Stanford, California
• E.R. Colby, R.J. England, R.J. Noble, J.E. Spencer
  SLAC, Menlo Park, California

Photonic crystal waveguides are promising candidates for laser-driven accelerator structures because of their ability to confine a speed-of-light mode in an all-dielectric structure. Because of the difference between the group velocity of the waveguide mode and the particle bunch velocity, fields must be coupled into the accelerating waveguide at frequent intervals. Therefore efficient, compact couplers are critical to overall accelerator efficiency. We present designs and simulations of high-efficiency coupling to the accelerating mode in a three-dimensional photonic crystal waveguide from a waveguide adjoining it at 90 degrees. We discuss details of the computation, including an optimization routine to modify the geometric parameters of the coupler for maximum efficiency, the resulting transmission, and estimates of the fabrication tolerance for these devices. We include some background on the accelerator structure and photonic crystal-based optical acceleration in general.

• J.B. Rosenzweig, G. Andonian, A. Fukasawa, E. Hemsing, G. Marcus, A. Marinelli, P. Musumeci, B.D. O'Shea, F.H. O'Shea, C. Pellegrini, D. Schiller, G. Travish
  UCLA, Los Angeles, California
• P.H. Bucksbaum, M.J. Hogan, P. Krejcik
  SLAC, Menlo Park, California
• M. Ferrario
  INFN/LNF, Frascati (Roma)
• S.J. Full
  Penn State University, University Park, Pennsylvania
• P. Muggli
  USC, Los Angeles, California

Recent initiatives at UCLA concerning ultra-short, GeV electron beam generation have been aimed at achieving sub-fs pulses capable of driving X-ray free-electron lasers (FELs) in single-spike mode. This uses of very low charge beams, which may allow existing FEL injectors to produce few-100 attosecond pulses, with very high brightness. Towards this end, recent experiments at the Stanford X-ray FEL (LCLS, first of its kind, built with essential UCLA leadership) have produced ~2 fs, 20 pC electron pulses. We discuss here extensions of this work, in which we seek to exploit the beam brightness in FELs, in tandem with new developments at UCLA in cryogenic undulator technology, to create compact accelerator/undulator systems that can lase below 0.15 Angstroms, or be used to permit 1.5 Angstrom operation at 4.5 GeV. In addition, we are now developing experiments which use the present LCLS fs pulses to excite plasma wakefields exceeding 1 TV/m, permitting a table-top TeV accelerator for frontier high energy physics applications.

• C. Eckardt, T. Bahlo, P. Bangert, R. Barday, U. Bonnes, M. Brunken, R. Eichhorn, J. Enders, M. Platz, Y. Poltoratska, M. Roth, F. Schneider, M. Wagner, A. Weber, B. Zwicker
  TU Darmstadt, Darmstadt
• W. Ackermann, W.F.O. Müller, T. Weiland
  TEMF, TU Darmstadt, Darmstadt

At the superconducting 130 MeV Darmstadt electron linac S-DALINAC* a source of polarized electrons** is being installed, extending the experimental capabilities with polarized electron and polarized photon probes for nuclear structure studies. This involves disassembling the existing low energy test stand and rebuilding the beam line in the accelerator hall. The beam itself is produced from a GaAs cathode by irradiation with a pulsed laser. The low-energy electron beam line includes diagnostic elements, a Wien filter for spin manipulation, a 100 keV Mott polarimeter for polarization measurement and a chopper-prebuncher section to modulate the time structure of the beam. At higher energies a 5-10 MeV Mott polarimeter and a 50-130 MeV Moeller polarimeter as well as a Compton transmission polarimeter will be installed to measure the beam polarization after acceleration. The Mott polarimeter is working with backscattered electrons under 165° scattering angle while for the Moeller polarimeter a wide-angle (3°-15°) spectrometer magnet was designed. We report on the performance of the test stand, the ongoing implementation, and the polarimeter research and development.

* A. Richter, Proc. EPAC 96, Sitges, p.110.
** Y. Poltoratska et al., AIP Conference Proc. 1149 (2009), p.983.

• J.K. Sekutowicz
  DESY, Hamburg
• P. Kneisel
  JLAB, Newport News, Virginia
• R. Nietubyc
  The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
• T. Rao, J. Smedley
  BNL, Upton, Long Island, New York

In this contribution, we report Quantum Efficiency (QE) test results with a hybrid lead/niobium superconducting RF (SRF) photoinjector at 2K and new Pb arc deposited cathodes at 300K. The ultimate goal of our effort is to build a Nb injector with the superconducting cathode made of lead, which, as reported in the past, demonstrated superior QE compared to other metallic superconducting elements. At first, we present the test results obtained with a 1.6-cell high purity Nb cavity with the emitting lead spot in the center of the back plate. The QE test results at room temperature and the SEM surface analysis of eight Pb cathodes, deposited recently under various conditions, are discussed in the second part of this contribution.

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

This paper reports about our efforts to develop a flangeable coaxial coupler for both HOM and fundamental coupling for 9-cell TESLA/ILC-type cavities. The cavities were designed in early 90‘s for pulsed operation with a low duty factor, less than 1 %. The proposed design of the coupler has been done in a way, that the magnetic flux B at the flange connection is minimized and only a field of <5 mT would be present at the accelerating field Eacc of ~ 36 MV/m (B =150 mT in the cavity). Even though we achieved reasonably high Q-values at low field, the cavity/coupler combination was limited in the cw mode to only ~ 7 MV/m, where a thermally initiated degradation occurred. We have improved the cooling conditions by initially drilling radial channels every 30 degrees, then every 15 degrees into the shorting plate. The modified prototype performed well up to 9 MV/m in cw mode. This paper reports about our experiences with the further modified coaxial coupler and about test results in cw and low duty cycle pulsed mode, similar to the TESLA/ILC operation conditions.

• J.K. Sekutowicz, M. Dohlus, A. Goessel, N. Mildner
  DESY, Hamburg

High frequency Higher Order Modes (HOM) propagating in the beam line of a superconducting linac can carry a substantial fraction of the energy deposited in accelerating structures by the beam. In this contribution, we report test results of the beam line absorber (BLA), which was designed and fabricated at DESY, and installed in the FLASH accelerator to absorb the HOM energy generated by high current beams. Two tests were carried out, in September 2008 and September 2009, during so called high current runs. The experiments confirmed the concept of the BLA design and showed remarkable agreement with computer modeling of the HOM energy absorption.

• A. Ushakov, S. Riemann, A. Schälicke
  DESY Zeuthen, Zeuthen

The development of an intense polarised positron sources provides a challenge for a new generation of linear colliders. The software framework Geant4, a toolkit for simulation of the passage of particles trough matter, features tracking capabilities of charged particles in electromagnetic fields, and also includes the description of polarisation transfer in scattering processes. Based on Geant4 a novel simulation tool, PPS-Sim*, has been developed to optimise the design and to determine polarisation, beam properties, as well as energy deposition in accelerator components. All source components and their parameters can be chosen easily and flexible. Helical undulator, laser-Compton and coherent Bremsstrahlung in crystals are available as positron production schemes. Target materials and geometry can be adjusted. Flux concentrator, quarter wave transformer and lithium lens are implemented as possible capture devices. Geometry, accelerating components and magnetic field configuration can be specified by the user. In this contribution, PPS-Sim will be presented, and selected results for linear collider applications will be discussed.

* PPS-Sim web page - http://pps-sim.desy.de

• M. Kuriki, H. Iijima
  HU/AdSM, Higashi-Hiroshima
• H. Hayano, Y. Honda, H. Sugiyama, J. Urakawa
  KEK, Ibaraki
• G. Isoyama, S. Kashiwagi, R. Kato
  ISIR, Osaka
• E. Katin, E. Khazanov, V. Lozhkarev, G. Luchinin, A. Poteomkin
  IAP/RAS, Nizhny Novgorod
• G. Shirkov, G.V. Trubnikov
  JINR, Dubna, Moscow Region

Aim of Super-conducting Test Facility (STF) at KEK is demonstrating technologies for International Linear Collider. In STF, one full RF unit will be developed and beam acceleration test will be made. In super-conducting accelerator, precise RF control in phase and power is essential because the input RF power should be balanced to beam accelerating power. To demonstrate the system feasibility, the beam accelerating test is an important step in R&D phase of STF and ILC. To provide ILC format beam for STF, we develop an electron source based on photo-cathode L-band RF gun. To generate ILC format beam, we developed a laser system based on Yb fiber oscillator in 40.6 MHz. The pulse repetition is decreased by picking pulses in 2.7 MHz, which meets ILC bunch spacing, 364 ns. The pulse is then amplified by YLF laser up to 8 uJ per pulse in 1 mm. The light is converted to 266 nm by SHG and FHG. Finally, 1.5 uJ per pulse is obtained and 3.2 nC bunch charge will be made. We report the basic performance of the laser system from the accelerator technology point of a view.

• H. Tomizawa, H. Dewa, H. Hanaki, A. Mizuno, T. Taniuchi
  JASRI/SPring-8, Hyogo-ken

We have developed a laser-induced Schottky-effect-gated photocathode gun since 2006. This new type of gun utilizes a laser's coherency to realize a compact laser source using Z-polarization of the IR laser on the cathode. This Z-polarization scheme reduces the laser pulse energy by reducing the cathode work function due to Schottky effect. Before this epoch-making scheme, photocathode guns had never utilized laser's coherency. A hollow laser incidence is applied with a hollow convex lens that is focused after passing the beam through a radial polarizer. According to our calculations (convex lens: NA=0.15), a Z-field of 1 GV/m needs 1.26 MW at peak power for the fundamental wavelength (792 nm) and 0.316 MW for the SHG (396 nm). Therefore, we expect that this laser-induced Schottky emission requires just a compact femtosecond laser oscillator as a laser source. Besides, a dichromatic laser scheme (photo-exciting: 780 nm; gating: 30 um) should be applied to polarized electron sources for International Linear Collider (ILC). We report the first feasibility study of this laser-induced Schottky-effect on several metal photocathodes by comparing radial and azimuthal polarizations.

• A. Deshpande
  Sokendai, Ibaraki
• S. Araki, M.K. Fukuda, N. Terunuma, J. Urakawa
  KEK, Ibaraki
• K. Sakaue, M. Washio
  RISE, Tokyo

At Laser Undulator Compact Source (LUCX) at KEK, we designed and made a new RF Gun with high mode separation of 8.6 MHz and high Q value as compared to earlier guns. This paper presents fabrication details, low power measurements and tuning procedures followed in making the gun cavity. We also discuss in detail, experimentation done using this gun and show the measurement results. Currently we produce 100 bunch per train but we plan to go for 300 or more bunch per train operation. This will make possible to have higher charge available for laser-beam collisions to generate high flux soft X-rays by Inverse Compton Scattering at our setup.

• K. Kan, T. Kondoh, T. Kozawa, K. Norizawa, A. Ogata, J. Yang, Y. Yoshida
  ISIR, Osaka

Time resolution of pulse radiolysis, which is a stroboscopic measurement technique, depends on electron bunch length. In order to improve the time resolution, femtosecond electron bunch generation at photocathode rf gun was investigated. A 1.6-cell S-band photocathode rf gun, similar to the Gun IV type at Brookhaven National Laboratory (BNL), was used. The rf gun consisted of a half cell and a full cell. A copper cathode was located in the half cell. The rf gun was driven by femtosecond UV laser pulse (266 nm), which was generated with third-harmonic-generation (THG) of Ti:Sapphire femtosecond laser (800 nm). The longitudinal and transverse dynamics of the electron bunch generated by the UV laser was investigated. The bunch length was measured with the dependence of energy spread on acceleration phase in a linac, which was set at the downstream of the rf gun. Transverse emittance at the linac exit was also measured with Q-scan method.

• T. Kondoh, K. Kan, T. Kozawa, K. Norizawa, A. Ogata, J. Yang, Y. Yoshida
  ISIR, Osaka

Femtosecond electron beam pulse radiolysis which has time resolution of 250 fs was achieved by a Photocathode RF gun LINAC in the ISIR, Osaka University. And geminate ion recombination (charged pair dynamics) in n-dodecane was studied. Kinetics of the Radical cation of n-dodecane was measured. As a result, the existence of the excited-radical cation, and generation of the radical cation via relaxation from the excited-radical cation were suggested. Those new results were obtained in the field of the radiation chemistry by the photocathode RF gun.

• J. Yang, K. Kan, T. Kondoh, Y. Murooka, N. Naruse, K. Tanimura, Y. Yoshida
  ISIR, Osaka
• J. Urakawa
  KEK, Ibaraki

Both ultrafast time-resolved radiolysis and electron diffraction based on photocathode rf electron guns have been developed in Osaka University to reveal the hidden dynamics of intricate molecular and atomic processes in materials. One of the photocathode rf guns has been used successfully to produce a 100-fs high-brightness electron single bunch with a booster linear accelerator and a magnetic bunch compressor. The time resolution of 240 fs was achieved at the first time in the pulse radiolysis. Another photocathode rf gun, which produces directly a near-relativistic 100-fs electron beam, has been developed to construct femtosecond electron diffraction. The megavolt electron diffraction patterns have been observed. The dependences of the emittance, bunch length and energy spread on the radio-frequency (rf) and space charge effects in the rf gun were investigated.

• M.Y. Yoshida, M. Aoki, Y. Kuno, A. Sato
  Osaka University, Osaka
• T. Nakamoto, T. Ogitsu, K. Tanaka, A. Yamamoto
  KEK, Ibaraki

An intense muon beam is mandatory for the next-generation experiments to search for lepton flavor violating processes in the muon sector. The COMET experiment, J-PARC ·10²¹, aims to search for muon to electron conversion with an unprecedented sensitivity.. The muon beam is produced from pion decays in a strong magnetic field generated by superconducting solenoid coils. The large-bore superconducting coils enclose the pion-production target to capture pions with a large solid angle. The magnetic field is designed to have a peak of 5T at the target. To avoid severe radiation from the target, thick shielding is inserted in the warm bore of the pion capture solenoid magnet. The proton beam is injected through the gap between the pion capture solenoid and the subsequent transport solenoid magnets. For this purpose, the bore of the pion capture solenoid has to be larger than 1 m. This paper describes the design of the pion capture solenoid magnet for the COMET experiment.

• Y. Yokoyama, T. Aoki, K. Sakaue, T. Suzuki, M. Washio, J. Yokose
  RISE, Tokyo
• H. Hayano, N. Terunuma, J. Urakawa
  KEK, Ibaraki
• S. Kashiwagi
  ISIR, Osaka
• R. Kuroda
  AIST, Tsukuba, Ibaraki

At Waseda University, we have been studying a high quality electron beam generation and its application experiments with Cs-Te photocathode RF-Gun. We have already succeeded in generating a stable high-charged single-bunch electron beam. To generate more intense electron beam, we designed a multi-bunch electron linac and developed the multi-pulse UV laser which irradiates to the cathode. The target values of the number of electron bunch and bunch charges are 100 bunches/train and 800 pC/bunch, respectively. In addition, we adopted the method of the amplitude modulation of the incident RF pulse to the S-band klystron in order to compensate the energy difference in each bunch because of the slow rise time of acceleration voltage in cavity and beam loading effect in the accelerating structure. In this conference, we will report design properties of our multi-bunch electron linac, the results of the multi-bunch electron beam diagnosis and the energy difference compensation using the RF amplitude modulation method.

• M. Petrarca, E. Chevallay, A.E. Dabrowski, M. Divall Csatari, S. Döbert, D. Egger, V. Fedosseev, T. Lefèvre, R. Losito, O. Mete
  CERN, Geneva

The high charge PHIN photo injector is studied at CERN as an electron source for the CLIC Test Facility (CTF3) drive beam as an alternative to the present thermionic gun. The objective of PHIN is to demonstrate the feasibility of a laser-based electron source for CLIC. The photo injector operates with a 2.5 cell, 3 GHz RF gun using a Cs2Te photocathode illuminated by UV laser pulses generated by amplifying and frequency quadrupling the signal from a Nd:YLF oscillator running at 1.5GHz. The challenge is to generate a beam structure of 1908μbunches with 2.33nC perμbunch at 1.5GHz leading to a high integrated train charge of 4446nC and nominal beam energy of 5.5MeV with current stability below 1%. In the present test stand, a segmented beam dump has been implemented allowing a time resolved measurement of the energy and energy spread of the electron beam. In this paper we report and discuss the measured transverse and longitudinal beam parameters for both the full and time gated train of bunches, and the obtained photocathode quantum efficiency. Laser pointing and amplitude stability results are discussed taking into account correlation between laser and electron beam.

• I.R. Bailey, J.A. Clarke, D.J. Scott
  Cockcroft Institute, Warrington, Cheshire
• I.R. Bailey
  Lancaster University, Lancaster
• C.G. Brown, J. Gronberg, L.B. Hagler, W.T. Piggott
  LLNL, Livermore, California
• L.J. Jenner
  Imperial College of Science and Technology, Department of Physics, London
• L. Zang
  The University of Liverpool, Liverpool

The efficiency of future positron sources for the next generation of high-energy particle colliders (e.g. ILC, CLIC, LHeC) can be improved if the positron-production target is immersed in the magnetic field of adjacent capture optics. If the target is also rotating due to heat deposition considerations then eddy currents may be induced and lead to additional heating and stresses. In this paper we present data from a rotating target wheel prototype for the baseline ILC positron source. The wheel has been operated at revolution rates up to 1800rpm in fields of the order of 1 Tesla. Comparisons are made between torque data obtained from a transducer on the target drive shaft and the results of finite-element simulations. Rotordynamics issues are presented and future experiments on other aspects of the positron source target station are considered.

• L. Zang
  Cockcroft Institute, Warrington, Cheshire
• I.R. Bailey
  Lancaster University, Lancaster
• M. Korostelev, A. Wolski
  The University of Liverpool, Liverpool

CLIC will need of order 10 to the 14 positrons per second to achieve its specified luminosity. For such a challenge, an undulator based scheme has been proposed as one of the options for the positron source. As CLIC may operate over a wide range of energy (from 0.5 TeV to 3 TeV), there is a large margin for us to push the performance of the whole system to be more efficient. We report on the undulator parameters and optimization of components of the source such as conversion target, AMD, solenoid and capture RF for different operational scenarios. In addition to maximizing the positron yield the polarization of the positron beam are also considered.

• W. Liu, W. Gai
  ANL, Argonne
• L. Rinolfi
  CERN, Geneva
• J. Sheppard
  SLAC, Menlo Park, California

We propose a viable positron source scheme that uses circularly polarized gamma rays generated from the main 250 GeV electron beam. The beam passes through a helical superconducting undulator with a magnetic field of ~ 1 Tesla and a period of a few centimeters. The gamma-rays produced in the undulator in the energy range between ~ 3 MeV ~ 100 MeV will be directed to a titanium target and produces polarized positrons. The positrons are then captured, accelerated and transported to a damping ring. Detailed parameter studies of this scheme including positron yield, undulator parameter dependence and target composition and geometry will be presented. Effects on the 250 GeV drive beam, including emittance, energy spread and energy loss from the beam passing through the undulator will also be discussed.

• W. Liu, W. Gai
  ANL, Argonne

We present an update on the ANL ILC positron source study. We examined the impact of different drive beam energies on the positron yield and polarization for the ILC RDR baseline undulator. The e⁺ yield is found to drop rapidly as the drive beam energy is reduced. We studied different undulator parameters for their effect on the positron yield and polarization when working at lower drive beam energies. Using a lower K (B field level) can increase the photon energy, but it is still very difficult to bring the yield up for low drive beam energies. For 250 GeV drive beam options, we studied the RDR undulator performance as a function of K. Instead of powering off some sections of the undulator, one can also consider lowering the B field to bring the positron yield back to the desired 1.5 e+/e-. We also studied the liquid lead target option for ILC positron source and the energy deposition in the reference design Ti target wheel.

• J. Gronberg, A. Abbott, C.G. Brown, J.B. Javedani, W.T. Piggott
  LLNL, Livermore, California
• J.A. Clarke
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire

The positron source at a future TeV scale electron linear collider will need to generate positrons at a rate two orders of magnitude larger than have been previously achieved. We report on a design of a 3.5 Tesla pulsed flux concentrator magnet which uses liquid nitrogen cooling of the flux concentrator plates to reduce the electrical resistance leading to reduced energy deposition and the ability to generate the required 1 ms pulse duration. This magnet can double the collection efficiency of positrons emitted from the target.

• M. Steck, C. Dimopoulou, A. Dolinskyy, B. Franzke, T. Katayama, S.A. Litvinov, F. Nolden, C. Peschke
  GSI, Darmstadt
• D. Möhl, L. Thorndahl
  CERN, Geneva

In the complex of the accelerators of the FAIR project the RESR storage ring is mainly designed as an accumulator ring for antiprotons. The continuous accumulation of pre-cooled batches with a cycle time of 10 s from the collector ring is essential to achieve the goal of a production rate of 10 million antiprotons per second. The accumulation in the RESR uses a stochastic cooling system which operates in longitudinal phase space, similar as previous antiproton accumulator rings at CERN and FNAL. The ingredients of the accumulation system, the ring lattice functions, the electrode design and the electrical circuits have been studied in detailed simulations. A system has been found which safely provides the required performance and offers the option of upgrades, if higher accumulation rate is required in future. Maximum intensities of 100 billion cooled antiprotons are planned which are expected to stay below the instability threshold.

• T. Bloch, C. Bauer, J. Leske, N. Pietralla
  TU Darmstadt, Darmstadt
• J. van de Walle
  KVI, Groningen

The REX-ISOLDE facility at CERN delivers a great variety of radioactive ion beams with energies up to 3.0 MeV/u and therefore allows nuclear structure physics experiments far from stability. A crucial point for the experimentalist is the knowledge of possible unwanted beam contaminations, either from the bunching and charge-breeding procedure (residual gas ions) or directly from the ion-production process (isobaric contaminants). The sources of these contaminations will be discussed, as well as possible ways of elimination during the post-acceleration. Methods to analyse the beam composition in the relevant energy range will be presented with an emphasis on the experimental challenges in Gamma-spectroscopy experiments and data analysis.

• Y. Yuri
  JAEA/TARRI, Gunma-ken
• E. P. Lee
  LBNL, Berkeley, California

The construction of the Extra Low ENergy Antiprotons (ELENA) upgrade to the Antiproton Decelerator (AD) ring has been proposed at CERN to produce a greatly increased current of low energy antiprotons for various experiments including, of course, anti-hydrogen studies. This upgrade involves the addition of a small storage ring and electrostatic beam lines. 5.3 MeV antiproton beams from AD are decelerated down to 100 keV in the compact ring and transported to each experiment apparatus. In this paper, we describe an electrostatic beam line from ELENA to ATRAP and magnetic shielding of the low-energy beam line against the ATRAP solenoid magnet. A possible design of this system is displayed.

• Y. Yuri, I. Ishibori, T. Ishizaka, S. Okumura, T. Yuyama
  JAEA/TARRI, Gunma-ken

To achieve ultra-low-fluence large-area uniform irradiation of ion beams for advanced applications in the field of materials sciences and biotechnology, a uniform-beam irradiation system has been developed using multipole magnets at the Japan Atomic Energy Agency (JAEA) cyclotron facility. The system consists of a beam attenuator for the wide-range intensity control, an electrostatic beam chopper for the control of irradiation time, scattering foils for conditioning of the initial beam distribution, octupole magnets for transverse tail-folding, sextupole magnets for the correction of the beam misalignment, and the diagnostic station of the two-dimensional beam profile. In this paper, recent experimental results are described, especially on the formation of a beam with a uniform transverse distribution by the combination of the sextupole and octupole magnets.

• M.W. McGee, C.R. Ader, K. Anderson, J. Hylen, M.A. Martens
  Fermilab, Batavia

The NOνA project will upgrade the existing Neutrino at Main Injector (NuMI) project beamline at Fermilab to accommodate beam power of 700 kW. The Medium Energy (ME) graphite target assembly is provided through an accord with the State Research Center of Russia Institute for High Energy Physics (IHEP) at Protvino, Russia. The effects of proton beam energy deposition within beamline components are considered as thermal stability of the target carrier assembly and alignment budget are critical operational issues. Results of finite element thermal and structural analysis involving the target carrier assembly is provided with detail regarding the target's beryllium windows.

mcgee@fnal.gov

• C.R. Ader, R.E. Reilly, J.H. Wilson
  Fermilab, Batavia

The NOνA Experiment will construct a detector optimized for electron neutrino detection in the existing Neutrino at Main Injector (NuMI) beamline. The NuMI beamline is capable of operating at 400 kW of primary beam power and the upgrade will allow up to 700 kW. Ceramic beam tubes are utilized in numerous kicker magnets in different accelerator rings at Fermilab. Kovar flanges are brazed onto each beam tube end, since kovar and high alumina ceramic have similar expansion curves. The tube, kovar flange, end piece, and braze foil alloy brazing material are stacked in the furnace and then brazed. The most challenging aspect of fabricating kicker magnets in recent years have been making hermetic vacuum seals on the braze joints between the ceramic and flange. Numerous process variables can influence the robustness of conventional metal/ceramic brazing processes. The ceramic-filler metal interface is normally the weak layer when failure does not occur within the ceramic. Differences between active brazing filler metal and the moly-manganese process will be discussed along with the applicable results of these techniques used for Fermilab production kicker tubes.

• C.R. Ader, D. Wildman
  Fermilab, Batavia

The NOνA Experiment will construct a detector optimized for electron neutrino detection in the existing Neutrino at Main Injector (NuMI) beamline. This beamline is capable of operating at 400 kW of primary beam power and the upgrade will allow up to 700 kW. The cavities will operate at 53 MHz and three of them will be installed in the Recycler beamline. Thermal stability of the cavities is crucial since this affects the tuning. Results of finite element thermal and structural analysis involving the copper RF cavity will be presented.

• M. Ieiri, A. Agari, E. Hirose, Y. Katoh, M. Minakawa, R. Muto, M. Naruki, Y. Sato, S. Sawada, Y. Suzuki, H. Takahashi, T. Takahashi, M. Takasaki, K.H. Tanaka, A. Toyoda, H. Watanabe, Y. Yamanoi
  KEK, Tsukuba
• H. Noumi
  RCNP, Osaka

In the hadron experimental hall at the 50-GeV Proton Synchrotron (PS) of J-PARC, the secondary beam line K1.8 with double stage separator is expected to provide 1-2 GeV/c kaon beams with less contamination of pions mainly for hadron and nuclear physics experiments with strangeness. An electrostatic (ES) separator is one of key elements of this secondary beam line. The ES separator will generate a 75kV/cm electrostatic field between parallel electrodes of 10cm gap and 6m in length along the beam direction. It is designed so as to be radiation-proof and to lower spark rate at the high intensity proton accelerator facility. The K1.8 line has two 6m ES separators with the intermediate focal point upstream of separators to reduce the pion backgrounds from the production target. The K-/π- ratio of the line is expected to have a larger value than 1 at the experimental target. Beam commissioning of the K1.8 has just started. We will report separator performance, optics design of the K1.8 beam line and the first result of the beam commissioning.

• E. Gschwendtner, K. Cornelis, I. Efthymiopoulos, A. Ferrari, A. Pardons, W. Treberspurg, H. Vincke, J. Wenninger
  CERN, Geneva
• D. Autiero
  IN2P3 IPNL, Villeurbanne
• A. Guglielmi
  INFN/LNL, Legnaro (PD)
• P.R. Sala
  Istituto Nazionale di Fisica Nucleare, Milano

The CNGS facility (CERN Neutrinos to Gran Sasso) aims at directly detecting muon to tau neutrino oscillations. An intense muon-neutrino beam (10¹⁷ muon neutrinos/day) is generated at CERN and directed over 732km towards the Gran Sasso National Laboratory, LNGS, in Italy, where two large and complex detectors, OPERA and ICARUS, are located. CNGS is the first long-baseline neutrino facility in which the measurement of the oscillation parameters is performed by observation of the tau-neutrino appearance. The facility is approved for a physics program of five years with a total of 22.5·10¹⁹ protons on target. Having resolved successfully some initial issues that occurred since its commissioning in 2006, the facility had its first complete year of physics in 2008. By the end of the 2009 physics run the facility will have delivered in total more than 5·10¹⁹ protons on target corresponding to ~2-3 tau neutrino events in the OPERA detector. The experiences gained in operating this 500 kW neutrino beam facility along with highlights of the beam performance in 2008 and 2009 are discussed.

• V. Variale, T. Clauser, A.C. Rainò, V. Valentino
  INFN-Bari, Bari
• M.A. Batazova, G.I. Kuznetsov, B.A. Skarbo
  BINP SB RAS, Novosibirsk

The charge breeding technique is used for Radioactive Ion Beam (RIB) production in the Isotope Separation On Line (ISOL) method in order of optimizing the re-acceleration of the radioactive element ions produced by a primary beam in a thick target. That technique is realized by using a device capable of increase the radioactive ion charge state from +1 to a desired value +n. In some experiments a continuous RIB of a certain energy could be required. The EBIS based charge breeding device cannot reach a real CW operation because the high charge state ions produced are extracted by the same part where the 1+ ions are injected, that is, from the electron collector. In this way, the ions extraction system, placed in the electron beam collector, can be left only to extract the n+ ions, and then the CW operation, at least in principle, could be reached. In this paper, a charge breeding test experiment based on a EBIS which has an e-gun with hollow cathode will be described. Furthermore, the status report of the experiment that is under way at the INFN Laboratori Nazionali di Legnaro (LNL) will be presented.

• M. Cavenago
  INFN/LNL, Legnaro (PD)
• F. Cavaliere, G. Maero, B. Paroli, R. Pozzoli, M. Romé
  Universita' degli Studi di Milano e INFN, Milano

In a Malmberg'Penning trap like ELTRAP an electron beam can be stored or propagated in a space charge dominated condition, due to the low acceleration voltage used; in particular we can test the longitudinal expansion of the electron bunch with several diagnostics, including Thomson scattering. Pulsed electron beams produced by an external photocathode source in the 1'10 keV energy range and with 4 ns length have been measured also by two electrostatic diagnostic systems. A proper software is needed to compensate for the capacitance of the pickup electrodes. Rf can be applied to the sectored electrode to produce a plasma source or to excite or to detect rotational modes; in particular the use of a new 8 sector electrode will allow up to m=3 modes.

• M. Cavenago
  INFN/LNL, Legnaro (PD)

In singly charged positive ion sources, the study of beam extraction is greatly simplified by the existence of a well defined place for plasma to beam transition, given by the well known Bohm criterion, where the ion flow speed equals the speed of sonic perturbation, known as Bohm speed. Most of the ion extraction simulation codes are implicity based on the concept of quasi neutrality in the plasma region, as limited by the Bohm criterion. In negative ion source the existence of an electron coextracted beam and of a magnetic filter makes the relevant speed less clear. Moreover there are several scale lengths to be considered: the Debye length, that is typically 0.01 mm, the electron and ion gyroradius, the H^- scattering, absorbtion and production length. In the development of negative ion source for NBI injector for ITER, the production of H^- at wall and the negative sheath so generated is also important. A critical evaluation of these regimes is obtained with 1D (one space dimension) models, mostly restricted to magnetic filter parallel to the extraction wall. Some remarks on 2D simulation codes is also given.

• M. Cavenago, T. Kulevoy, S. Petrenko
  INFN/LNL, Legnaro (PD)
• V. Antoni, G. Serianni, P. Veltri
  Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova

The development of neutral beam injectors (NBI) for tokamak like the ITER project and beyond requires high performance and huge negative ion sources (40 A of D- beam required); it was recently accepted that inductive plasma coupled (ICP) radiofrequency sources are the preferred option. It is therefore useful to have a moderate size source of modular design to test and verify both construction technologies and components and simulation codes; here the NIO1 design (60 kV, 9 beamlets of 15 mA H^- each) and construction status are described. Source is assembled from disk shaped modules, for rapid replacement; the beamlets are arranged in 3 times 3 square matrix so that 90 degree rotation of modules is possible and allows to cross or to align the magnetic filters used in the source. The 2 MHz rf coil and the rf window are a simply replaceable module. Extensive rf absorption and magnetic coil simulations were performed. Related beam simulation and fast emittance scanner development are described elsewhere.

• K. Kondo
  Department of Energy Sciences, Tokyo Institute of Technology, Yokohama
• R. Dabrowski, M. Okamura
  BNL, Upton, Long Island, New York
• T. Kanesue
  RIKEN Nishina Center, Wako

In a laser ion source, a high power pulsed laser shot focused on a solid state target produces laser ablation plasma. This plasma has initial velocity towards the normal direction of the target and simultaneously expands three dimensionally. Since charge state distribution, velocity distribution and plasma temperature strongly depends on laser power density, power density is one of the important parameter to the angular distribution of plasma. Angular distribution of expanding plasma was measured by changing laser power density. Details of the experiment will be shown in the paper.

• T. Yorita, M. Fukuda, K. Hatanaka, M. Kibayashi, S. Morinobu, A. Tamii
  RCNP, Osaka

The upgrade program of the AVF cyclotron is in progress since 2004 at Research Center for Nuclear Physics (RCNP), Osaka Univ., for improving the quality, stability and intensity of accelerated beams. An 18 GHz superconducting ECRIS has been installed to increase beam currents and to extend the variety of ions, especially for highly charged heavy ions which can be accelerated by RCNP cyclotrons. The production development of several ion like B, C ~ Xe by gas mixing or MIVOC has been performed. In order to extend the variety of ions more, metal viper or spatter system has also been installed to 10GHz NEOMAFIOS with minimum modifications. The details of these recent developments will be presented.

• T. Ishibashi, T. Hattori, N. Hayashizaki, L. Liang
  RLNR, Tokyo

High intensity heavy ion beam acceleration in the low energy region is one of the most difficult conditions to achieve, because the space charge effect is extremely strong. In order to generate a high intensity beam using linacs, we have to avoid beam loss by the space charge effect as much as possible. Multibeam acceleration has been proposed as a possible method of reducing the space charge effect. If one cavity could be used to accelerate several beams, a significant gain would be made in installation space and operational cost saving. In this study we look at a multibeam type radio frequency quadrupole (RFQ) linac in order to accelerate several beams using a single cavity. The RFQ electrodes are placed in an IH type cavity; This structure is known as a IH-RFQ linac. GSI in Germany proposed a multibeam type IH-RFQ linac with several beam channels in a single cavity. However, this multibeam type IH-RFQ linac has yet to be manufactured. We manufactured a 2-beam type IH-RFQ linac as a prototype of the multibeam type IH-RFQ. The linac outputs C²⁺ beam of 60 keV/u and 44 mA/channel in the design value. We will report about the beam acceleration test of the linac.

• N. Kuroda, Y. Enomoto, H. Imao, C.H. Kim, Y. Matsuda, H.A. Torii, Y. Yamazaki
  The University of Tokyo, Institute of Physics, Tokyo
• H. Higaki
  HU/AdSM, Higashi-Hiroshima
• H. Hori
  MPQ, Garching, Munich
• Y. Kanai, A. Mohri, Y. Nagata
  RIKEN, Wako, Saitama
• K. Kira
  Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima
• K. Michishio
  Tokyo University of Science, Tokyo
• H. Saitoh
  University of Tokyo, Chiba
• M. Shibata
  KEK, Tsukuba

The ASACUSA collaboration at CERN has been developed a unique Mono-energetic Ulta-Slow Antiproton beam Source for High-precision Investigation (MUSASHI) for collision studies between antiproton and atoms at very low energy region, which also used as an intense ultra-low energy antiproton source for the synthesis of antihydrogen atoms in order to test CPT symmetry. MUSASHI consists of a multi-ring electrode trap housed in a bore surrounded by a superconducting solenoid, which works with a sequential combination of the CERN Antiproton Decelerator and the Radio-Frequency Quadrupole Decelerator. GM-type refrigerators were used to cool the solenoid and also the bore at 4K to avoid losses of antiprotons with residual gasses. Up to 1.8 millions of antiprotons per one AD cycle were successfully trapped and cooled. MUSASHI achieved to accumulate more than 12 millions of cold antiprotons by stacking several AD shots. Such cooled antiprotons were extracted as 150 or 250eV beams with various bunch lengths from 2 micoroseconds to 30 seconds long, whose energy width was the order of sub-eV. The beam intensity was enhanced by a radial compression technique for the trapped antiproton cloud.

• Y. Higurashi, M.K. Fujimaki, A. Goto, E. Ikezawa, O. Kamigaito, M. Kase, M. Komiyama, T. Nakagawa, J. Ohnishi, Y. Watanabe
  RIKEN Nishina Center, Wako
• T. Aihara, M. Tamura, A. Uchiyama
  SHI Accelerator Service Ltd., Tokyo

The next generation heavy ion accelerator facility, such as the RIKEN RIBF, requires great variety of high charged heavy ions with a magnitude higher beam intensity than currently achievable. In the last decade, performance of the ECR ion sources has been dramatically improved with increasing the magnetic field and RF frequency to enhance the density and confinement time of plasma. Furthermore, the effects of the key components (magnetic field configuration, gas pressure etc) on the ECR plasma have been revealed. Such basic studies give us how to optimize the ion source structure. Based on these studies and the technology, we successfully constructed the new 28GHz SC-ECRIS which has a flexible magnetic field configuration to enlarge the ECR zone and to optimize the field gradient at ECR point. In the test experiment, we obtained the direct evidence that the field gradient and the zone size strongly affect the beam intensity. It concludes that the gentler field gradient and large ECR zone size gives intense beam of highly charged heavy ions from ECR plasma. In this contribution, we report the systematic study of these effects on the beam intensity of highly charged heavy ions.

• J. Ohnishi, Y. Higurashi, O. Kamigaito, T. Nakagawa
  RIKEN Nishina Center, Wako

The superconducting ECR ion source enabled to use a 28 GHz microwave source had been developed to provide intense beam of highly charged heavy ions like U³⁵⁺ to the RIKEN RI-beam factory (RIBF) since 2007. The first plasma was lit in May of 2009 and it was succeeded in providing the uranium beam to the RIBF in December. In this operation, uranium ions were supplied with sputter method and two 18 GHz microwave sources were used. The beam intensity of the uranium ion exceeded 14μAmps, which was more than five times larger than that for 18 GHz ECR ion source of a usual type. The extraction system consists of the accel-decel electrode system, a solenoid coil and a 90 degreeanalyzing magnet. We measured the profiles and emittances of the extracted beams for several ion species and compared with the calculated results with 'OPERA-3d' including space charge effect. And we shall discuss the beam dynamics at the extraction region such as the relationship between the beam emittance and the operating parameters.

• K. Kondo
  Department of Energy Sciences, Tokyo Institute of Technology, Yokohama
• R. Dabrowski, M. Okamura
  BNL, Upton, Long Island, New York
• T. Kanesue
  Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka

The Electron Beam Ion Source (EBIS) project at Brookhaven National Laboratory is a new heavy ion pre-injector for Relativistic Heavy Ion Collider (RHIC) and NASA Space Radiation Laboratory science programs. An important requirement for EBIS is an ion source capable of efficiently providing a variety of heavy ion species to many users within short period of time. In that respect, Laser Ion Source (LIS), which can supply many heavy ion species from solid targets, is a good candidate for RHIC-EBIS, however, LIS has an issue to be resolved. This is the requirement of limited current in low energy beam transport. LIS in the condition that laser power density is low, is expected to provide limited current with long pulse length. The discussions of the experimental results are presented.

• K.O.LEE. Lee, K.H. Chung
  KAPRA, Cheorwon
• H.G. Joo, S.K. Kauh
  SNU, Seoul
• S.K. Ko
  University of Ulsan, Ulsan

The physics design of a Photo Fission Ion Source (PFIS) which will be used in a heavy ion accelerator is introduced. The design variables being considered are asymmetric magnetic field, cooling, neutron reflector and modulator (high density graphite), UCx target, bremsstrahlung power, microwave power and fission fragments (ions). Based on the design studied performed by using Monte Carlo codes and nuclear data, we will present the results, performance, optimization, ion distribution, bremsstrahlung power dependent radiation distribution, and temperature distributions. Finally we will conclude the feasibility of PFIS.

• E. Syresin, V.P. Volnyh
  JINR, Dubna, Moscow Region

The radioactive ion isotopes 11C⁶⁺, 10C⁶⁺ and others are produced at interaction of primary carbon ion beam with target. These isotopes can be applied for Positron Emission Tomography. The projectile-fragmentation method is used for the production of radioactive isotopes. The intensity of radioactive ion beam is defined by the target optimal thickness, material and by available longitudinal and transverse acceptances of transportation channel. An increase of target thickness permits to improve production rate of radioactive ion beams, however it increase the energy and angle spreads of secondary ions and finally it gives a reduction of number of useful radioactive ions which can be transported to the PET camera. The GEANT 4 simulations related to formation of 11C⁶⁺ secondary ion beams at interaction with different targets are discussed.

• E. Syresin, D.E. Donets, E.D. Donets, E.E. Donets, V.V. Salnikov, V.B. Shutov
  JINR, Dubna, Moscow Region
• T. Honma, M. Kanazawa, K. Noda
  NIRS, Chiba-shi

The 11C isotopes are produced in the nitrogen gas target irradiated by a proton beam. If the nitrogen target contains 5% of hydrogen, about 5·E12 methane molecules can be produced each 20 minutes. The separated methane is loaded into the ion source. The technique used for formation of radioactive carbon beams was developed and tested in the JINR electron string ion source (ESIS) Krion-2. The measured conversion efficiency of methane molecules to carbon ions is rather high; it corresponds to 17 % for C⁴⁺ ions. The experimentally obtained C⁴⁺ ion intensity in ESIS was about 2·E9 ppp. The new ESIS-5T is under construction in JINR now at project ion intensity of 6·E9 ppp. Accelerated 12C ion beams are effectively used for cancer treatment at HIMAC. The positron emission tomography is the most effective way of tumor diagnostics. The intensive radioactive 11C ion beam could allow both these advantages to be combined. It could be used both for cancer treatment and for on-line PET. Formation of a primary radioactive ion beam at an intensity on the tumor target of 1·E8 pps allows the cancer treatment by the scanning radiation method and on-line dose verification.

• E. Syresin, D.E. Donets, E.D. Donets, E.E. Donets, V.M. Drobin, V.B. Shutov
  JINR, Dubna, Moscow Region
• A.E. Dubinov, R.M. Garipov, I.V. Makarov
  VNIIEF, Sarov (Nizhnii Gorod)
• A.V. Shabunov
  JINR/LHE, Moscow

The Electron String Ion Source (ESIS) developed at JINR is effectively used here during the last decade. The Tubular Electron String Ion Source (TESIS) has been put forward recently to obtain a 1-2 orders of magnitude increase in the ion output as compared with ESIS. The project is aimed at creating TESIS and studying the electron string in the tubular geometry. The new tubular source with a superconducting solenoid up to 5 T is under construction now. The method of the off axis TESIS ion extraction will be realized to get TESIS beam emittance comparable with ESIS emittance. It is expected that this new TESIS will meet all rigid conceptual and technological requirements and should provide an ion output approaching 10 mA of Ar¹⁶⁺ ions in the pulsed mode and about 10 μA of Ar¹⁶⁺ ions in the average current mode. Design, construction and test of separate TESIS systems are discussed in this report.

• I. Bustinduy, D. Fernandez-Cañoto, D. de Cos
  ESS Bilbao, Bilbao
• J. Alonso, M. Eguiraun, R. Enparantza, M. Larrañaga
  Fundación TEKNIKER, Eibar (Gipuzkoa)
• F.J. Bermejo
  Bilbao, Faculty of Science and Technology, Bilbao
• V. Etxebarria, J. Jugo, J. Portilla
  University of the Basque Country, Faculty of Science and Technology, Bilbao
• D.C. Faircloth, S.R. Lawrie, A.P. Letchford
  STFC/RAL/ISIS, Chilton, Didcot, Oxon
• J. Feuchtwanger
  ESS-Bilbao, Zamudio
• S. Jolly
  Imperial College of Science and Technology, Department of Physics, London
• J. Lucas
  Elytt Energy, Madrid

The rationale behind the Bilbao Accelerator Ion Source Test Stand (ITUR) project is to perform a comparison between different kinds of hydrogen ion sources using the same beam diagnostics setup. In particular, a direct comparison will be made in terms of the emittance characteristics of Penning-type sources such as those currently being used in ISIS (UK) and those of microwave type such as CEA-Saclay and INFN. The aim here pursued is to build an Ion Source Test Stand where virtually any type of source can be tested and, thus, compared to the results of other sources under the same gauge. It would then be possible to establish a common ground for effectively comparing different ion sources. The work here presented reports on the first simulations for the H-/H⁺ extraction system, as well the devices that conform the diagnostic vessel: Faraday Cup, Pepperpot and Retarding Potential Analyzer (RPA), among others.

• I. Bustinduy, N. Garmendia, H. Hassanzadegan, D. de Cos
  ESS Bilbao, Bilbao
• F.J. Bermejo
  Bilbao, Faculty of Science and Technology, Bilbao
• V. Etxebarria, J. Portilla
  University of the Basque Country, Faculty of Science and Technology, Bilbao
• J. Feuchtwanger
  ESS-Bilbao, Zamudio
• S. Jolly, J.K. Pozimski, P. Savage
  Imperial College of Science and Technology, Department of Physics, London
• A.P. Letchford
  STFC/RAL/ISIS, Chilton, Didcot, Oxon

The main objective of the Bilbao Front End Test Stand (ETORFETS) is to set up a facility to demonstrate experimentally the design ideas for the future ESS LINAC that are being proposed in discussion forums by the technical scientific community. ETORFETS is focused on the first stage of the linear accelerator, namely, that of the Radio-Frequency Quadrupole (RFQ) and its pre and post beam transport systems. The RFQ bunches, focuses transverse and longitudinally, and accelerates charged particles in the low-energy range (up to ~ 3 MeV), thus becoming one of the main components of the accelerating structure. The first RFQ simulations, performed in Superfish and GPT software packages, will be presented in this work.

• D.C. Faircloth, S.R. Lawrie, A.P. Letchford, M. Perkins
  STFC/RAL/ISIS, Chilton, Didcot, Oxon

The Front End Test Stand (FETS) under construction at the Rutherford Appleton Laboratory is the UK's contribution to research into the next generation of High Power Proton Accelerators (HPPAs). Running at duty cycles of up 50 Hz with pulse lengths of 2 ms are required. This paper presents initial Hminus beam currents and emittance measurements for long pulse lengths.

• V.G. Dudnikov, R.P. Johnson
  Muons, Inc, Batavia
• Y.S. Derbenev, Y. Zhang
  JLAB, Newport News, Virginia

The operation of the RHIC facility at BNL and the Electron Ion Colliders (EIC) under development at Jefferson Laboratory and BNL need high brightness ion beams with the highest polarization. Charge exchange injection into a storage ring or synchrotron and Siberian snakes have the potential to handle the needed polarized beam currents, but first the ion sources must create beams with the highest possible polarization to maximize collider productivity, which is proportional to a high power of the polarization. We are developing one universal H-/D- ion source design which will synthesize the most advanced developments in the field of polarized ion sources to provide high current, high brightness, ion beams with greater than 90% polarization, good lifetime, high reliability, and good power efficiency. The new source will be an advanced version of an atomic beam polarized ion source (ABPIS) with resonant charge exchange ionization by negative ions. An integrated ABPIS design will be prepared based on new materials and an optimized magnetic focusing system. Polarized atomic and ion beam formation, extraction, and transport for the new source will be computer simulated.

• V.G. Dudnikov, R.P. Johnson
  Muons, Inc, Batavia
• M.P. Stockli, R.F. Welton
  ORNL, Oak Ridge, Tennessee

Development of novel modifications of H^- source designs is proposed. The new source will be an advanced version of a Penning DT SPS (Dudnikov-Type Penning Surface Plasma Source) which will generate brighter beam in noiseless discharge, deliver up to 20 mA average current with better electrode cooling using new materials, and have longer lifetime, fast beam chopping capability, and reduced cesium loss.

• V.G. Dudnikov, R.P. Johnson
  Muons, Inc, Batavia
• G. Dudnikova
  UMD, College Park, Maryland
• M.P. Stockli, R.F. Welton
  ORNL, Oak Ridge, Tennessee

In this project we are developing an RF H^- surface plasma source which will synthesize the most important developments in the field of negative ion sources to provide high pulsed and average current, high brightness, good lifetime, high reliability, and higher power efficiency. We describe two planned modifications to the present SNS external antenna source in order to increase the plasma density near the output aperture: 1) replacing the present 2 MHz plasma-forming solenoid antenna with a 13 MHz saddle-type antenna and 2) replacing the permanent multicusp magnetic system with a weaker electro-magnet. Progress of this development will be presented.

• R. Sah, A. Dudas, M.L. Neubauer
  Muons, Inc, Batavia
• J.W. Kwan
  LBNL, Berkeley, California

Induction linear accelerators are featured in accelerator-based research currently supported by the Office of Fusion Energy Sciences. Over the next few years, the research will concentrate on developing intense ion sources and on studying the physics of spatial compression, neutralized transport, and focusing of the beam. The large diameter of lithium alumino-silicate ion emitters for large currents represents the current state of the art for emission densities of 1-1.5 mA/cm². Also, operating temperatures of the surface are limited by the temperature of alumina-potted heater packages. We propose a novel system for increasing the emission of lithium ions from β-eucryptite through modification of the surface morphology by sputter etching with argon plus other gases. The resulting local field enhancement will increase the ion emission over that of a microscopically flat surface. In addition, a free-standing graphite heater assembly will be used to increase the temperature of the surface of the emission source.

• R. Dabrowski, M. Okamura
  BNL, Upton, Long Island, New York
• T. Kanesue
  Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka
• K. Kondo
  Department of Energy Sciences, Tokyo Institute of Technology, Yokohama

The Laser Ion Source is an efficient method for generating heavy ions for acceleration. The output produces high current and high charge-state beams from almost any type of elemental species. Using the Laser Ion Source apparatus, we consider improving the efficiency of this method by heating the target prior to laser irradiation. Prior deposition of any thermal energy into the target could add with the energy being delivered by the pulsed laser to produce higher current beams. These beams could be composed of higher charge-state ions and/or an increased net number of ions. We investigate by using a retrofitted heater to heat the target to a variety of high temperatures and subsequently analyze the produced beam.

• T. Kanesue
  Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka
• R. Dabrowski, M. Okamura
  BNL, Upton, Long Island, New York
• K. Kondo
  Department of Energy Sciences, Tokyo Institute of Technology, Yokohama

A laser ion source can provide high-current highly-charged ions with a simple structure. Previously we have demonstrated acceleration of >60 mA carbon and aluminum ion beams using a direct plasma injection scheme. However, it was not easy to control the ion pulse width. Especially to provide longer ion pulse, a plasma drift length which is the distance between laser target and extraction point, has to be extended and the plasma is diluted severely. We apply a solenoid field to prevent reduction of ion density at the extraction point. A solenoid field of a few hundred Gauss enhanced the ion density up to 40 times. We present these results, including details of the solenoidal field effects on the expanding laser plasma.

• L.H.J. Bozyk
  TU Darmstadt, Darmstadt
• D.H.H. Hoffmann, H. Kollmus, P.J. Spiller
  GSI, Darmstadt

The central accelerator SIS100 of the FAIR-facility will provide high intensity, intermediate charge state heavy ion beams. In order to assure a reliable operation with the intermediate charge states, a special synchrotron design, including ion catcher system had to be developed. Intermediate charge state heavy ions suffer from high cross sections for ionization. Due to the dedicated synchrotron layout, ions which have been further stripped by collisions with residual gas atoms are not lost uncontrolled onto the beam pipe but are caught by the ion catcher system in the cryogenic arcs. The construction and test of a cryo-catcher prototype at GSI is a workpackage of the EU-FP7 project COLMAT. A prototype catcher including cryostat will be set-up at GSI to perform measurements with heavy ion beams of the heavy ion synchrotron SIS18.

• J. Stadlmann, H. Kollmus, E. Mustafin, I.J. Petzenhauser, P.J. Spiller, I. Strašík, N.A. Tahir, C. Trautmann
  GSI, Darmstadt
• L.H.J. Bozyk, M. Krause
  TU Darmstadt, Darmstadt
• M. Tomut
  INFIM, Bucharest

Within the frame of the EuCARD program, the GSI Darmstadt is performing accelerator R&D in workpackage 8: ColMat. The effort is focused on materials important for building the FAIR accelerator facility at GSI and the LHC upgrade at CERN. Accelerator components and especially protection devices have to be operated in high dose environments. The radiation hazard occurs either by the primary proton and ion beams or the secondary radiation. Detailed numerical simulations have been carried out to study the damage caused to solid targets by the full impact of the LHC beam as well as the SPS beam. Tungsten, copper and graphite targets have been studied. Experimental an theoretical studies on radiation damage on materials used for the LHC upgrade and the FAIR accelerators are performed at the present GSI experimental facilities. Technical decisions based on these results will have an impact on the FAIR component specifications. A cryogenic ion-catcher prototype will be constructed and tested. The ion-catcher is essential for reaching highest heavy ion beam intensities in SIS100. The prototype will be set-up at GSI to perform measurements with heavy ion beams of synchrotron SIS18.

• A. Mazzolari, E. Bagli, V. Guidi
  INFN-Ferrara, Ferrara
• S. Baricordi, P. Dalpiaz, D. Vincenzi
  UNIFE, Ferrara
• A. Carnera, D. De Salvador
  Univ. degli Studi di Padova, Padova
• G. Della Mea
  INFN/LNL, Legnaro (PD)
• A.M. Taratin
  JINR, Dubna, Moscow Region

Channeling in bent crystals is a technique with high potential to steer charged-particle beams for several applications in accelerators physics. Revisited methods of silicon micromachining techniques allowed one to realize a new generation of crystals. Characterizations using x-ray diffraction, atomic force microscopy, high resolution transmission electron microscopy and ion beam analysis techniques, showed high quality of the crystals. A specifically designed holder allowed to mechanically bend a crystal at given curvature and remove unwanted torsion. Characterization of such crystals with 400 GeV at CERN H8 external line highlighted 85% single-pass efficiency. A selected crystal has been installed inside the SPS ring in the environment of the CERN experiment UA9 and successfully employed for collimation of the circulating beam.

On behalf of UA9 collaboration

• M.J. Shirakata, T. Oogoe
  KEK, Ibaraki

The beam transport line between 3 GeV Rapid Cycling Synchrotron and Main Ring has a beam collimator system in order to improve the quality of injected beam in the main ring. The beam power deposited into the collimators is required to be increased for high intensity beam operation. The tolerance of existing radiation shield becomes insufficient, even though there is no heat problem. The gate-type shield system has been preparing in order to satisfy both the radiation shielding and feasibility of maintenance. The development of movable gate-type shield system is reported here, which fully covers more than 20 meters long collimator section.

• R. Chamizo, J. Borburgh, B. Goddard, A. Mereghetti, R. Versaci, W.J.M. Weterings
  CERN, Geneva

Linac4 is the new H^- linear accelerator under construction at CERN aiming to double the brightness of the beam injected to the CERN PS Booster (PSB) for delivering proton beams to experiments or further CERN accelerators, down to the LHC. The injection system in the PSB is based on the H^- charge exchange where the 160 MeV H^- beam is converted into an H⁺ beam by stripping the electrons with a carbon foil. A beam dump located inside a pulsed magnet for the injection bump will intercept the unstripped ions (H0 and H-) and measure the collected charge to detect the relative efficiency and degradation of the stripping foil. The challenge of the dump design is to meet the requirements of a beam dump providing a current measurement and at the same time minimizing the perturbation of the magnetic field of the surrounding pulsed magnet. This paper describes all phases of the dump design and the main issues related to its integration in the line.

• E. Laface, W. Scandale, L. Tlustos
  CERN, Geneva
• V. Ippolito
  INFN-Roma, Roma

The UA9 experiment was performed in 6 MDs from May to November 2009 with the goal of studying the collimation properties of a crystal in the framework of a future exploitation in the LHC collimation system. An important parameter evaluated for the characterization of the crystal collimation is the efficiency of halo extraction when the crystal is in channeling mode. In this paper it is explained how this efficiency can be measured using a pixel detector, the Medipix, installed in the Roman Pot of UA9. The number of extracted particles counted by the Medipix is compared with the total number of circulating particles measured by the Beam Current Transformers (BCTs): from this comparison the efficiency of the system composed by the crystal, used in channeling mode, and a tungsten absorber is proved to be greater than 85%.

• E. Laface, S.D. Fartoukh, F. Schmidt
  CERN, Geneva

The Phase I Luminosity Upgrade of LHC (SLHC) will be based on a new Nb-Ti inner triplet for the high luminosity region ATLAS and CMS. The new proposed layout aims at pushing beta* down to 30 cm replacing the current LHC inner triplet, with longer ones operating at lower gradient (123 T/m) and therefore offering enough aperture for the beam to reduce beta* to its prescribed value. As a consequence of this new longer interaction region, the number of parasitic encounters will increase from 15 to 21 before the separation dipole D1, with an impact on the dynamic aperture of the machine. In this paper the effect of the beam-beam interaction is evaluated for the SLHC layout and optics, at injection and in collision, evaluating the possible impact of a few additional parasitic collisions inside and beyond the D1 separation dipole till the two beams do no longer occupy the same vacuum chamber. Whenever needed, a comparison with the nominal LHC will be given. Then a possible backup collision optics will be discussed for the SLHC, offering a much wider crossing angle at an intermediate beta* of 40 cm in order to reach a target dynamic aperture of 7.5 σ.

• W. Scandale, R. Losito
  CERN, Geneva
• A.M. Taratin
  JINR, Dubna, Moscow Region

A number of tests were performed by the UA9 Collaboration* in the North area of the SPS in view of investigating crystal-particles interactions for future application in hadron colliders. The rate of nuclear reactions was measured with 400 GeV proton beams directed into a silicon bent crystal. In this way the background induced by the crystal itself either in amorphous or in channeling orientation was revealed. The results provide fundamental information to put in perspective the use of silicon crystals to assist halo collimation in hadron colliders, whilst minimizing the induced loss. Crystals made of Germanium were also investigated in view of the expected increase of the collimation efficiency respect to silicon. Finally, crystals were tested in axial orientation and with incoming particles of negative charge. The collected results are presented in details.

* http://greybook.cern.ch/programmes/experiments/UA9.html

• Y. Lee, V. Gandel, D.C. Kiselev, D. Reggiani, M. Seidel, S. Teichmann
  PSI, Villigen

A simulation based optimization of a collimator system at the 590 MeV PSI proton accelerator is presented, for the ongoing beam power upgrade from the current 1.2 MW [2 mA] towards 1.8 MW [3 mA]. The collimators are located downstream of the 4 cm thick graphite meson production target. These are designed to shape the optimal beam profile for low-loss beam transport to the neutron spallation source SINQ. The optimized collimators are predicted to withstand the beam intensity up to 3 mA, without sacrificing intended functionalities. The collimator system is under the heavy thermal load generated by a proton beam power deposition approximately of 240 kW at 3 mA, and it needs an active water cooling system. Advanced multiphysics simulations are performed for a set of geometric and material parameters, for the thermomechanical optimization of the collimator system. In particular, a FORTRAN subroutine is integrated into CFD-ACE+, for calculating local beam stopping power in the collimator system. Selected results are then compared with those of full MCNPX simulations.

• T.R. Edgecock
  STFC/RAL, Chilton, Didcot, Oxon
• J.J. Back
  University of Warwick, Coventry
• J.R.J. Bennett
  STFC/RAL/ISIS, Chilton, Didcot, Oxon
• C.N. Booth, G.P. Skoro
  Sheffield University, Sheffield
• S.J. Brooks
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon

The UK programme of high power target developments for a Neutrino Factory is centred on the study of high-Z materials (tungsten, tantalum). A description of lifetime shock tests on candidate materials is given as part of the research into a solid target solution. A fast high current pulse is applied to a thin wire of the sample material and the lifetime measured from the number of pulses before failure. These measurements are made at temperatures up to ~2000 K. The stress on the wire is calculated using the LS-DYNA code and compared to the stress expected in the real Neutrino Factory target. It has been found that tantalum is too weak to sustain prolonged stress at these temperatures but a tungsten wire has reached over 26 million pulses (equivalent to more than ten years of operation at the Neutrino Factory). An account is given of the optimisation of secondary pion production from the target and the issues related to mounting the target in the muon capture solenoid and target station are discussed.

• T.R. Edgecock
  STFC/RAL, Chilton, Didcot, Oxon
• C.D. Beard, J.A. Clarke, S.A. Griffiths, C. Hill, S.P. Jamison, J.K. Jones, A. Kalinin, K.B. Marinov, N. Marks, P.A. McIntosh, B.D. Muratori, J.F. Orrett, Y.M. Saveliev, B.J.A. Shepherd, R.J. Smith, S.L. Smith, S.I. Tzenov, A.E. Wheelhouse
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• J.S. Berg
  BNL, Upton, Long Island, New York
• N. Bliss, B.G. Martlew, C.J. White
  STFC/DL, Daresbury, Warrington, Cheshire
• M.K. Craddock
  UBC & TRIUMF, Vancouver, British Columbia
• J.L. Crisp, C. Johnstone
  Fermilab, Batavia
• Y. Giboudot
  Brunel University, Middlesex
• E. Keil
  CERN, Geneva
• D.J. Kelliher, S. Machida
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• S.R. Koscielniak
  TRIUMF, Vancouver
• F. Méot
  CEA, Gif-sur-Yvette
• J. Pasternak
  Imperial College of Science and Technology, Department of Physics, London
• S.L. Sheehy, T. Yokoi
  JAI, Oxford

The Electron Model for Many Applications (EMMA) will be the World's first non-scaling FFAG and is under construction at the STFC Daresbury Laboratory in the UK. Construction is due for completion in March 2010 and will be followed by commissioning with beam and a detailed experimental programme to study the functioning of this type of accelerator. This paper will give an overview of the motivation for the project and describe the EMMA design and hardware. The first results from commissioning will be presented in a separate paper.

• G.P. Skoro, C.N. Booth
  Sheffield University, Sheffield
• J.J. Back
  University of Warwick, Coventry
• J.R.J. Bennett, S.A. Gray, A.J. McFarland
  STFC/RAL/ISIS, Chilton, Didcot, Oxon
• T.R. Edgecock
  STFC/RAL, Chilton, Didcot, Oxon

Recently reported results on the tungsten lifetime/fatigue tests under conditions expected in the Neutrino Factory target have strengthened the case of solid target option for a Neutrino Factory. This paper gives description of the detailed measurements of the tungsten properties at high temperature and high stress. We have performed extensive set of measurements of the surface displacement and velocity of the tungsten wires that were stressed by passing a fast, high current pulse through a thin sample. Radial and longitudinal oscillations of the wire were measured by a Laser Doppler Vibrometer. The wire was operated at temperatures of 300-2500 K by adjusting the pulse repetition rate. In doing so we have tried to simulate the conditions (high stress and temperature) expected at the Neutrino Factory. Most important result of this study is an experimental confirmation that strength of tungsten remains high at high temperature and high stress. The experimental results have been found to agree very well with LS-DYNA modelling results.

• X.P. Ding, D.B. Cline
  UCLA, Los Angeles, California
• J.S. Berg, H.G. Kirk
  BNL, Upton, Long Island, New York

A study of a pion production and capture system for a 4MW target station for a neutrino factory or muon collider is presented. Using the MARS code, we simulate the pion production produced by the interaction of a free liquid mercury jet with an intense proton beam. We study the variation of meson production with the direction of the proton beam relative to the target. We also examine the influence on the meson production by the focusing of the proton beam. The energy deposition in the capture system is determined and the shielding required in order to avoid radiation damage is discussed.