• R. Versteegen, O. Delferrière, O. Napoly, J. Payet, D. Uriot
  CEA, Gif-sur-Yvette

The International Linear Collider reference design is based on a collision scheme with a 14 mrad crossing angle. Consequently, the detector solenoid and the machine axis do not coincide. It provokes a position offset of the beam at the Interaction Point in addition to a beam size growth. These effects are modified by the insertion of the anti-DID (Detector Integrated Dipole) aiming at reducing background in the detector. Furthermore a crab cavity is necessary to restore a 'head on' like collision, leading to higher luminosity. This introduces new beam distortions. In this paper, optics studies and simulations of beam transport in the Interaction Region taking these elements into account are presented. Correction schemes of the beam offset and beam size growth are exposed and their associated tolerances are evaluated.

• J.W. Amann, R. Arnold, A. Seryi, D.R. Walz
  SLAC, Menlo Park, California
• K. Kulkarni, P. Rai, P. Satyamurthy, V. Tiwari
  BARC, Mumbai
• H. Vincke
  CERN, Geneva

Significant progress has been made in the design of an 18MW Beam Dump for 500 GeV electron/positron beams at an ILC. The beam dump design is based on circulating water with a vortex-like flow pattern to dissipate and remove the energy deposited by the beam. Multi-dimensional technology issues have been addressed to design the beam dump system. Detailed thermal-hydraulic analysis was carried out in all the critical regions of the beam dump which include, 1) location of highest volumetric power deposition by the beam, 2) location of highest linear power deposition, 3) entrance window region, 4) vessel walls etc. Based on this analysis, the sizing of the beam dump and its components, water flow rate and inlet jet velocity, optimum location of the beam path in the beam dump, beam sweep radius etc have been estimated. In addition, preliminary mechanical design of the beam dump, cooling circuit details, sizing of the hydrogen/oxygen recombiner system, ion exchange and 7Be removal, prompt and residual radioactivity studies etc have been carried out. Details of this work will be presented.

• F. Furuta, T. Konomi, K. Saito
  KEK, Ibaraki

We have started high gradient R&D with the combination of ICHIRO shape, sliced large grain niobium, and chemical polishing (CP). We fabricated one large grain ICHIRO single cell cavity that had end cell shape of ICHIRO 9-cell but no end group. We processed this cavity surface by centrifugal barrel polishing (CBP) and CP. This cavity successfully achieved the high gradient of 42MV/m at the first vertical test. We made series test by repeating CP on this cavity. The results of series test will be reported.

• F. Furuta, T. Konomi, K. Saito
  KEK, Ibaraki

In our high gradient R&D of ICHIRO cavities at KEK, we have found some problems related to HOM coupler and high power RF input coupler port on beam tube: end group. One is the difficulties of rinsing in complex structures like HOM coupler. The other is Q-slope at high filed more than 40MV/m. The cavities without end group did not show such a high field Q-slope. At first step, we tested much stronger and aggressive rinsing method; wiping, brushing, and mega-sonic rinsing, against end group. The details and results of these rinsing effects will be reported.

• F. Furuta, T. Konomi, K. Saito
  KEK, Ibaraki

We have continued high gradient R&D of ICHIRO 9-cell cavities at KEK. The maximum gradient of ICHIRO 9-cell cavity #5 that has no end groups on beam tube was still limited around 36MV/m so far. The 9-cell performances were sometimes limited by triggered field emission (FE) by multipactings. We suspected the residual gas in the cavity might be one of the sources of triggered FE. The cavity was closed during vertical test in our system. Other labs evacuated cavity during vertical test. In order to improve the vacuum of cavity during vertical test, we made evacuation system in our cavity test stand. The comparison of results for vertical test with and without evacuation will be reported.

• K. Kubo
  KEK, Ibaraki
• D. Wang
  IHEP Beijing, Beijing

For preserving low emittance beam in the ILC (International Linear Collider) main linacs, Dispersion Matching Steering (DMS) is planed to be used as a main correction method. The linacs are following the earth's curvature and the designed vertical dispersion in the linacs should not be zero. For this reason, the orbit difference due to beam energy difference will have to be measured accurately and tolerance of scale error of beam position monitors (BPM) can be tight. Here, the tolerance of the scale error are estimated by tracking simulations. Choice of optics design for relaxing the tolerance is also discussed.

• N. Ohuchi, H. Hayano, N. Higashi, E. Kako, Y. Kondou, H. Nakai, S. Noguchi, T. Saeki, M. Satoh, M. Sawabe, T. Shidara, T. Shishido, A. Terashima, K. Tsuchiya, K. Watanabe, A. Yamamoto, Y. Yamamoto, K. Yokoya
  KEK, Ibaraki
• T.T. Arkan, S. Barbanotti, H. Carter, M.S. Champion, R.D. Kephart, J.S. Kerby, D.V. Mitchell, Y. Orlov, T.J. Peterson, M.C. Ross
  Fermilab, Batavia
• A. Bosotti, C. Pagani, R. Paparella, P. Pierini
  INFN/LASA, Segrate (MI)
• D. Kostin, L. Lilje, A. Matheisen, W.-D. Möller, H. Weise
  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 has been constructed by INFN. The module for four KEK cavities is being modified at present. The assembly of the cryomodules is scheduled from January 2010, and the operation of the system is scheduled from June 2010 at the KEK-STF. In this paper, the construction of the S1-Global cryomodule will be presented.

• K. Saito, F. Furuta, T. Konomi
  KEK, Ibaraki

Dr. Matsumoto in KEK and his colleague have developed the MO flange for vacuum sealing of normal conducting high peak power RF wave-guide. This is impedance free sealing. We have applied this sealing to SRF cavity technology instead of indium sealing. We used pure aluminum gasket for the sealing material. We had a difficulty on the titanium flange but succeeded to establish leak tightness in super-fluid Helium by stainless flange. In this paper, we will report the R&D results.

• K. Saito, F. Furuta, T. Konomi
  KEK, Ibaraki

We are developing LL high gradient SRF cavity for ILC. Recently we have observed a Q-slope problem at higher gradient over 35-40MV/m on the full end single cell cavities, which have a HOM coupler and an input coupler on a beam tube. This problem might be due to poor rinsing in such a complicate structure. We have studied to strengthen cleaning by improvement of the nozzle shape used high pressure water rinsing, inside ultrasonic cleaning, steam cleaning, and so on. In this paper we will report these results.

• K. Saito, F. Furuta, T. Konomi
  KEK, Ibaraki

We are developing large grain/single crystal niobium material for ILC collaborating with Tokyo Denkai. These materials are very much promising to obtain high SRF cavity performance with cost-effective production. We have fabricated two 9-cell cavities from these large grain niobium materials and made cold test to evaluate the SRF performance. In this paper, we will report cavity fabrications and preparations and cold test results.

• Y. Yamamoto, H. Hayano, E. Kako, S. Noguchi, M. Sato, T. Shishido, K. Umemori, K. Watanabe
  KEK, Ibaraki

Vertical tests of five 1.3GHz 9-cell cavities (MHI#5-#9) have been done totally 17 times from 2008 to 2009 for S1-Global project in KEK-STF, which is planned in 2010. MHI#7 cavity achieved 33.6MV/m, which was the best result, and the others below 30MV/m. After the exchange for new EP acid on May/2009, many brown stains (niobium oxide) were observed on the interior surface of the cavity, and onset gradient of radiation level measured at the top flange of cryostat was much lower. After several vertical tests, the effect by this phenomenon was gradually relaxed. After four cavities reached above 25MV/m, the gradient suddenly dropped due to the unknown cause at the next vertical test. Two of four cavities were recovered above 25MV/m at the final vertical test again. However, any cavity in KEK-STF did not reach ILC specification (Eacc=35MV/m, Q0=0.8x10¹⁰) yet. This means that more improvement for cavity fabrication and surface treatment is necessary. In this presentation, the summary of the vertical tests for S1-Global project in KEK-STF will be reported.

• Y. Yamamoto, H. Hayano, E. Kako, S. Noguchi, M. Sato, T. Shishido, K. Umemori, K. Watanabe
  KEK, Ibaraki

Vertical test for 1.3GHz 9-cell cavity has been routinely carried out over one year since 2008 in KEK-STF. Temperature mapping (T-mapping) system using 352 carbon resistors was introduced to identify the heating location at thermal quenching of the cavity. T-mapping system in STF identified perfectly the heating location in every vertical test for S1-Global project. As X-ray-mapping system, 142 PIN diodes were used, and the x-ray emission site was detected under heavy field emission. During the vertical test, it is convenient to display the result of T-mapping and X-ray-mapping by online monitor system. For this purpose, the new online monitor system was developed by using EPICS (Experimental Physics and Industrial Control System) and Java script, and introduced in recent several vertical tests. As a data acquisition system, nine data loggers (MW100, YOKOGAWA) are used, and signals from totally 540 channels are stored every 0.1 sec. The online display for T-mapping and X-ray-mapping is updated automatically every 5 seconds. In this report, the summary of T-mapping/X-ray-mapping result and the online monitor system will be described in detail.

• T. Konomi
  Sokendai, Ibaraki
• F. Furuta, K. Saito
  KEK, Ibaraki

We have designed Demountable Damped Cavity (DDC) for ILC main linac. DDC has two design concepts. One is the coaxial waveguide for HOM damping, which can strongly couple HOM's. Accelerating mode is reflected by a choke filter. The axial symmetry can reduce the beam kick effect. The other concept is demountable structure which can make easy cleaning of end group in order to suppress the Q-slope problem at a high field. In this paper we will report the RF design and measurement results in model cavity.

• K. Sennyu, H. Hara, H. Hitomi, K. Kanaoka, M. Matsuoka, T. Yanagisawa
  MHI, Kobe

MHI has supplied superconducting cavity for the ILC R&D project to KEK in Japan for the last few years. We are improving the technology to design and fabricate the superconducting cavities. We can present some example of our work that have improved the productivity of the superconducting cavities.

• Y. Iwashita, H. Fujisawa, M. Ichikawa, H. Tongu, S. Ushijima
  Kyoto ICR, Uji, Kyoto
• M. Masuzawa, T. Tauchi
  KEK, Ibaraki

A prototype of a permanent magnet quadrupole lens for ILC final focus doublet is fabricated. In order to demonstrate the feasibility, it will be tested in a real beam line. Such practical experiences include its shipping, storage, handling, installation, alignment technique, and so on. Because permanent magnets cannot be switched off in contradistinction to electromagnets, they should be evacuated from beam lines when no interference is desired and the process should be quick with enough reproducibility. The magnetic center and strength stability including reproducibility are also important issues during the beam test. In order to reduce interferences with current ongoing testing items at ATF2, the magnet will be installed at a further upstream position of the ATF2 beam line. The installation and test plan will be described.

• G. Shirkov, Ju. Boudagov, Yu.N. Denisov, A. Dudarev, I.N. Meshkov, B.M. Sabirov, A.N. Sissakian, G.V. Trubnikov
  JINR, Dubna, Moscow Region

The investigations on ILC siting in the Dubna region and ILC technical activity at JINR are presented. International intergovernmental status of JINR, stable geological and plain relief conditions, comfortable location and well developed infrastructure create a set of advantages of the JINR site in the neighborhood of Dubna. The shallow layout of accelerator tunnel makes it possible to use a communication gallery at the surface instead of second one. This is an effective way of significant cost reduction of all conventional facilities and explicit labor of the project. The results of the preliminary geological engineering surveys along the supposed route of the ILC in Dubna area of Moscow region are presented.

• E. Gschwendtner, A. Apyan, K. Elsener, A. Sailer, J.A. Uythoven
  CERN, Geneva
• R. Appleby, M.D. Salt
  UMAN, Manchester
• A. Ferrari, V.G. Ziemann
  Uppsala University, Uppsala

The 1.5TeV CLIC beams, with a total power of 14MW per beam, are disrupted at the interaction point due to the very strong beam-beam effect. As a result, some 3.5MW reach the main dump in form of beamstrahlung photons. About 0.5MW of e⁺e^- pairs with a very broad energy spectrum need to be disposed along the post-collision line. The conceptual design of this beam line will be presented. Emphasis will be on the optimization studies of the CLIC post-collision line design with respect to the energy deposition in windows, dumps and scrapers, on the design of the luminosity monitoring for a fast feedback to the beam steering and on the background conditions for the luminosity monitoring equipment.

• E. Gschwendtner, K. Elsener
  CERN, Geneva
• R. Appleby, M.D. Salt
  UMAN, Manchester
• A. Apyan
  Fermilab, Batavia
• A. Ferrari
  Uppsala University, Uppsala

The 1.5TeV CLIC beams, with a total power of 14MW per beam, are disrupted at the interaction point due to the very strong beam- beam effect. The resulting spent beam products are transported to suitable dumps by the post-IP beam line, which generates beam losses and causes the production of secondary cascades towards the interaction region. In this paper the electromagnetic background at the IP are presented, which were calculated using biased Monte Carlo techniques. Also, a first estimate is made of neutron back-shine from the main beam dump.

• P. Lebrun
  CERN, Geneva
• P.H. Garbincius
  Fermilab, Batavia

High-energy accelerators are large projects funded by public money, developed over the years and constructed via major industrial contracts both in advanced technology and in more conventional domains such as civil engineering and infrastructure, for which they often constitute one-off markets. Assessing their cost, as well as the risk and uncertainty associated with this assessment is therefore an essential part of project preparation and a justified requirement by the funding agencies. Stemming from the experience with large circular colliders at CERN, LEP and LHC, as well as with the Main Injector, the Tevatron Collider Experiments and Accelerator Upgrades, and the NOvA Experiment at Fermilab, we discuss sources of cost variance and derive cost risk assessment methods applicable to the future linear collider, through its two technical approaches for ILC and CLIC. We also address disparities in cost risk assessment imposed by regional differences in regulations, procedures and practices.

• D. Schulte, R. Corsini, B. Dalena, J.-P. Delahaye, S. Döbert, G. Geschonke, A. Grudiev, J.B. Jeanneret, E. Jensen, P. Lebrun, Y. Papaphilippou, L. Rinolfi, G. Rumolo, H. Schmickler, F. Stulle, I. Syratchev, R. Tomás, W. Wuensch
  CERN, Geneva
• E. Adli
  University of Oslo, Oslo

The physics experiments at CLIC will require that the machine scans lower than nominal centre-of-mass energy. We present different options to achieve this and discuss the implications for luminosity and the machine design.

• J. Snuverink, W. Herr, C. Jach, J.B. Jeanneret, D. Schulte, F. Stulle
  CERN, Geneva

The Compact Linear Collider (CLIC) accelerator has strong precision requirements on the position of the beam. The beam position will be sensitive to external dynamic magnetic fields (stray fields) in the nanotesla regime. The impact of these fields on the CLIC main beam has been studied by performing simulations on the lattices and tolerances have been determined. Several mitigation techniques will be discussed.

• G. Rumolo, J.B. Jeanneret, D. Schulte
  CERN, Geneva

The maximum tolerable pressure value in the chamber of the CLIC electron Main Linac is determined by the threshold above which the fast ion instability sets in over a bunch train. Instability calculations must take into account that, since the accelerated beam becomes transversely very small, its macroscopic electric field can reach values above the field ionization threshold. In this paper we first discuss threshold values of the electric field for field ionization and the extent of the transverse region that gets fully ionized along the ML. Then, we show the results of the instability simulations from the FASTION code using the new model, and consequently review the pressure requirement in the ML.

• B. Dalena, D. Schulte
  CERN, Geneva

Beam-Beam background is one of the main issues of the CLIC MDI at 3 TeV CM. The background level have a significant impact on the interaction region design. This paper presents a study of the background expected rates versus luminosity according to different beam parameters and considering different machine conditions, using an integrated simulation of the Main LINAC and BDS sub-systems.

• I. Syratchev, A. Cappelletti
  CERN, Geneva

One crucial development for CLIC is an adjustable high-power rf device which controls the output power level of individual Power Extraction and Transfer Structures (PETS) even while fed with a constant drive beam current. The CLIC two-beam rf system is designed to have a low, approximately 10^-7, breakdown rate during normal operation and breakdowns will occur in both accelerating structures and the PETS themselves. In order to recover from the breakdowns and reestablish stable operation, it is necessary to have the capability to switch off a single PETS/accelerating structure unit and then gradually ramp generated power up again. The baseline strategy and implementation of such a variable high-power mechanism is described.

• P.K. Skowronski, S. Bettoni, R. Corsini, A.E. Dabrowski, S. Döbert, A. Dubrovskiy, F. Tecker
  CERN, Geneva
• C. Biscari
  INFN/LNF, Frascati (Roma)
• W. Farabolini
  CEA, Gif-sur-Yvette
• R.J.M.Y. Ruber
  Uppsala University, Uppsala

The objective of the CLIC Test Facility CTF3 is to demonstrate the key feasibility issues of the CLIC two-beam technology: the efficient generation of a very high current drive beam and its stable deceleration in 12 GHz resonant structures, to produce high-power RF pulses and accelerate the main beam with an accelerating gradient of 100 MV/m. The construction and commissioning of CTF3 has taken place in stages from 2003. Many milestones had already been reached, including the first demonstration at the end of 2009 of a factor 2 x 4 re-combination of the initial drive beam pulse, thus reaching a beam current of 25 A. In this paper we summarise the commissioning highlights and the issues already validated at the earlier stages. We then show and discuss the latest results obtained, in view of the completion of the CLIC feasibility demonstration due for the end of 2010.

• R. Tomás, B. Dalena, J. Pfingstner, D. Schulte, J. Snuverink
  CERN, Geneva
• J.K. Jones
  Cockcroft Institute, Warrington, Cheshire
• A. Latina
  Fermilab, Batavia
• J. Resta-López
  JAI, Oxford

The CLIC BDS tuning, alignment and feedbacks studies have been typically performed independently and only over particular sections of the BDS. An effort is being put to integrate all these procedures to realistically evaluate the luminosity performance.

• B. Dalena, D. Schulte, R. Tomás
  CERN, Geneva

The main detector solenoid and associated magnets can have an important impact on the CLIC luminosity. These effects are discussed for different solenoid designs. In particular, the luminosity loss due to incoherent synchrotron radiation in the experiment solenoid and QD0 overlap is evaluated. The impact of the AntiDiD (Anti Detector integrated Dipole) on luminosity and compensated techniques on beam optic distortion are also discussed.

• R. Tomás, B. Dalena, E. Marin, D. Schulte, G. Zamudio
  CERN, Geneva
• D. Angal-Kalinin, J.-L. Fernandez-Hernando, F. Jackson
  Cockcroft Institute, Warrington, Cheshire
• J. Resta-López
  JAI, Oxford
• A. Seryi
  SLAC, Menlo Park, California

The CLIC Conceptual Design Report must be ready by 2010. This paper aims at addressing all the critical points of the CLIC BDS to be later implemented in the CDR. This includes risk evaluation and possible solutions to a number of selected points. The smooth and practical transition between the 500 GeV CLIC and the design energy of 3 TeV is also studied.

• J.K. Jones, D. Angal-Kalinin
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire

It is proposed to investigate the option of moving the positron source to the end of the main linac as a part of the central integration in the International Linear Collider project. The positron source incorporates an undulator at the end of the main linac and the photons generated in the undulator are transported to the target, located at a distance of around 400m. The dogleg design has been optimised to provide the required transverse off-set at the location of the target and to give minimum emittance growth at 500 GeV. The design of the dogleg and the tolerances on beam tuning as a result of locating this dogleg in the beginning of the beam delivery system are presented.

• V.F. Khan, A. D'Elia, R.M. Jones
  UMAN, Manchester
• A. Grudiev, W. Wuensch, R. Zennaro
  CERN, Geneva

Our earlier design* for an accelerating structure to suppress the wakefields in the CLIC main accelerating cavities has been modified. This structure combines strong detuning of the cell frequencies with waveguide-like damping by providing the structure with four attached manifolds which loosely couple a portion of the wakefields from each cell. The amended geometry reduces the surface pulse temperature heating by approximately 20%. We report on the overall parameters of the fundamental mode, together with details on damping higher order dipole modes. In order to adequately suppress the wakefield we interleave the frequencies of eight successive structures.

* Khan and Jones, TU5PFP007, PAC'09, Vancouver, Canada 2009.

• W. Gai, M.E. Conde, J.G. Power
  ANL, Argonne
• C.-J. Jing
  Euclid TechLabs, LLC, Solon, Ohio

In this paper, we present a linear collider concept based on drive beam generation from an RF photoinjector, and employing dielectric structures for power extraction and acceleration. The collider is based on a modular design with each module providing 100 GeV net acceleration. A high current drive beam is produced using a low frequency RF gun (~ 1GHz), and subsequently accelerated to ~1 GeV using conventional standing wave cavities. High frequency (20 GHz) RF power, extracted from the drive beam using a low impedance dielectric structure, is used to power the main linacs, which are based on high impedance high gradient dielectric loaded accelerating structures. We envision this scheme will produce high gradients (300 MeV/m), leading to a very compact design. The modularity of the design will allow a staged construction that will enable extension to multi-TeV energies.

• A. Lunin, I.G. Gonin, N. Solyak, V.P. Yakovlev
  Fermilab, Batavia

In the paper the results are presented for calculation of the transverse wake and RF kick from the power and HOM couplers of the ILC acceleration structure. The RF kick was calculated stand-alone by HFSS, CST MWS and COMSOL codes while the wake kick was calculated by GdfidL. The calculation precision and convergence for both cases are discussed and compared to the results obtained independently by other group.

• J. Gronberg, B. Stuart
  LLNL, Livermore, California
• A. Seryi
  SLAC, Menlo Park, California

The realization of a photon collider option at a future TeV scale electron linear collider requires the generation of high average power picosecond laser pulses. Recirculating cavities have been proposed to reduce the amount of laser power that needs to be generated, however, these cavities impose stringent limits on the wavefront quality and stability of the laser architecture. We report on a design study of a high average power laser amplifier architecture which can produce the required laser time structure and stability to drive these recirculating cavities.

• M.-H. Wang, Y. Cai, Y. Nosochkov
  SLAC, Menlo Park, California

SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing photon source that would be housed in the 2.2-km PEP-II tunnel*,**. The proposed PEP-X storage ring is one of the possibilities. The goal of the PEP-X design is to develop an optimal light source design with horizontal emittance less than 100 pm at 4.5 GeV and vertical emittance of 8 pm corresponding to the diffraction limit of 1-Å X-ray. The low emittance design requires a lattice with strong focusing leading to high natural chromaticity and therefore to strong sextupoles. The latter cause reduction of dynamic aperture. The horizontal dynamic aperture required at PEP-X injection point is about 10 mm. In order to achieve the desired dynamic aperture, transverse non-linearities of PEP-X are studied. The program LEGO*** is used for particle tracking simulations. The technique of frequency map is used to analyze the nonlinear behavior. The effects of the non-linearities are tried to minimize. The details and results of dynamic aperture optimization are discussed in this paper.

*,** R. Hettel et al., 'IDEAS FOR A FUTURE PEP-X LIGHT SOURCE', EPAC08, 'CONCEPTS FOR THE PEP-X LIGHT SOURCE', PAC09.
*** Y. Cai et al., 'LEGO: A Modular accelerator design code', PAC97, 1997.

• B. Parker, M. Anerella, J. Escallier, P. He, A.K. Jain, A. Marone, P. Wanderer, K.-C. Wu
  BNL, Upton, Long Island, New York
• P. Bambade
  LAL, Orsay
• B. Bolzon, A. Jeremie
  IN2P3-LAPP, Annecy-le-Vieux
• P.A. Coe, D. Urner
  OXFORDphysics, Oxford, Oxon
• C. Hauviller, E. Marin, R. Tomás, F. Zimmermann
  CERN, Geneva
• N. Kimura, K. Kubo, T. Kume, S. Kuroda, T. Okugi, T. Tauchi, N. Terunuma, T. Tomaru, K. Tsuchiya, J. Urakawa, A. Yamamoto
  KEK, Ibaraki
• A. Seryi, C.M. Spencer, G.R. White
  SLAC, Menlo Park, California

The KEK ATF2 facility, with a well instrumented beam line and Final Focus (FF), is a proving ground for linear collider (LC) technology to demonstrate the extreme beam demagnification and spot stability needed for a LC FF*. ATF2 uses water cooled magnets but the baseline ILC calls for a superconducting FF**. Thus we plan to replace some ATF2 FF magnets with superconducting ones made via direct wind construction as planned for the ILC. With no cryogenic supply at ATF2, we look to cool magnets and current leads with a few cryocoolers. ATF2 FF coil winding is underway at BNL and production warm magnetic measurements indicate good field quality. Having FF magnets with larger aperture and better field quality than present FF might allow reducing the beta function at the FF for study of focusing regimes relevant to CLIC. Our ATF2 magnet cryostat will have laser view ports for cold mass movement measurement and FF support and stabilization requirements under study. We plan to make stability measurements at BNL and KEK to relate ATF2 FF magnet performance to that of a full length ILC R&D prototype at BNL. We want to be able to predict LC FF performance with confidence.

* ATF2 proposal, volumes 1 and 2 at http://lcdev.kek.jp/ILC-AsiaWG/WG4notes/atf2/proposal/index.html
** International Linear Collider Reference Design Report, ILC-REPORT-2007-001, August 2007.

• A. Alekou
  Imperial College of Science and Technology, Department of Physics, London

Muon ionization cooling provides the only practical solution to prepare high brilliance beams necessary for a neutrino factory or muon colliders. The muon ionization cooling experiment (MICE)* is under development at the Rutherford Appleton Laboratory (UK). It comprises a dedicated beam line to generate a range of input emittance and momentum, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. A first measurement of emittance is performed in the upstream magnetic spectrometer with a scintillating fiber tracker. A cooling cell will then follow, alternating energy loss in liquid hydrogen and RF acceleration. A second spectrometer identical to the first one and a particle identification system provide a measurement of the outgoing emittance. In May 2010 it is expected that the beam and most detectors will be commissioned and the time of the first measurement of input beam emittance closely approaching. The plan of steps of measurements of emittance and cooling, that will follow in the rest of 2010 and later, will be reported.

This abstract is submitted by the chear of the MICE speaker bureau. A member of the collaboration will be soon identified to present the poster and added a co-author.

• A. Sato
  Osaka University, Osaka

FFAG lattices with racetrack-shape has been studied to cool muon beams. The ring has straight sections with FFAG magnets, which makes enough space to install kicker magnets to inject and extract the muon beam. Wedge absorbers using superfluid helium and RF cavities are installed to the ring. This paper reports progress of the study.

• A. Sato
  Osaka University, Osaka

The COMET is an experiment to search for the process of muon to electron conversion in a muonic atom, and is in its design phase to be carried out at J-PARC in near future. The experiment uses a long superconducting solenoid channels from a pion production target to a detector system. In order, to study the solenoid channel the g4beamline is used for the magnetic field calculation and beam tracking. This paper reports the status of the simulation studies.

• Y. Bao
  IHEP Beijing, Beijing
• A. Caldwell, G.X. Xia
  MPI-P, München
• D. Greenwald
  MPI für Physics, Muenchen

Low energy muon beams are useful for a wide range of physics experiments. High quality muon beams are also required for muon colliders and neutrino factories. The frictional cooling method holds promise for delivering slow muon beams with narrow energy spreads. With this technology, we consider the production of a cold muon beam from a surface muon source, such as that at the Paul Scherrer Institute. A cooling scheme based on frictional cooling is outlined. Simulation results show that the efficiency of slow muon production can be raised to 1%, which is significantly higher than current schemes.

• C.T. Rogers
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• A. Alekou
  Imperial College of Science and Technology, Department of Physics, London
• M. Martini, G. Prior
  CERN, Geneva
• D.V. Neuffer
  Fermilab, Batavia
• D. Stratakis
  BNL, Upton, Long Island, New York
• C. Y. Yoshikawa
  Muons, Inc, Batavia
• M.S. Zisman
  LBNL, Berkeley, California

We discuss alternative designs of the muon capture front end of the Neutrino Factory International Design Study (IDS). In the front end, a proton bunch on a target creates secondary pions that drift into a capture channel, decaying into muons. A sequence of RF cavities forms the resulting muon beams into strings of bunches of differing energies, aligns the bunches to (nearly) equal central energies, and initiates ionization cooling. This design is affected by limitations on accelerating gradients within magnetic fields. The effects of gradient limitations are explored, and mitigation strategies are presented.

• A. Alekou, J. Pasternak
  Imperial College of Science and Technology, Department of Physics, London
• C.T. Rogers
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon

The Neutrino Factory is a planned particle accelerator complex that will produce an intense, focused neutrino beam, using neutrinos from muon decay. Such high neutrino intensities can only be achieved by reducing the muon beam emittance using an ionization cooling system. The G4MICE software is used to study the performance of various cooling cell configurations. A comparison is drawn between the cooling in the FS2 cells, the baseline Neutrino Factory and doublet cells. The beam dynamics in each of cooling channels are presented. The lattices are compared with respect to the equilibrium emittance, muon transmission, acceptance and evolution of emittance along the channel. Conclusions for a possible optimisation of the future muon cooling channel of the Neutrino Factory are presented.

• M. Apollonio
  Imperial College of Science and Technology, Department of Physics, London
• M.A. Rayner
  OXFORDphysics, Oxford, Oxon

In the Muon Ionization Cooling Experiment (MICE) at RAL muons are produced and transported in a dedicated beamline connecting the production point (target) to the diffuser, a mechanism inside the first spectrometer solenoid designed to inflate the initial normalized emittance up to 10 mm rad in a controlled fashion. In order to match the incoming muons to the downstream experiment, covering all the possible values of the emittance-momentum matrix, an optimisation procedure has been devised which is based upon a genetic algorithm coupled to the tracking code G4Beamline. Details of beamline tuning and initial measurements are discussed.

• M. Apollonio
  Imperial College of Science and Technology, Department of Physics, London
• A.P. Blondel
  DPNC, Genève
• D.J. Kelliher
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon

Monitoring the muon beam properties in the final stage of the Neutrino Factory (the Decay Ring) is important for the understanding of the beam itself and a crucial piece of information for the downstream physics detectors. The main topics to be assessed are: knowledge of the muon beam energy, divergence of the muon beam and muon beam current. In the framework of the International Design Study for the Neutrino Factory (IDS-NF) a Race Track model Decay Ring based on G4beamline has been produced to understand how electrons from muon decays can be used to infer the energy properties of the beam via the spin depolarisation technique. The use of other codes, like Zgoubi, to generate a realistic beam including effects like spin polarisation, are considered. A general discussion on the remaining topics is presented.

• A.J. Dobbs, M. Apollonio, K.R. Long, J. Pasternak
  Imperial College of Science and Technology, Department of Physics, London
• D.J. Adams
  STFC/RAL/ISIS, Chilton, Didcot, Oxon

The international Muon Ionisation Cooling Experiment (MICE) is designed to provide a proof of principal of the ionisation cooling technique proposed to reduce the muon beam phase space at a future Neutrino Factory or Muon Collider. The pion production target is a titanium cylinder that is dipped into the proton beam of the Rutherford Appleton Laboratory's ISIS 800 MeV synchrotron. Studies of the particle rate in the MICE muon beam are presented as a function of the beam loss induced in ISIS by the MICE target. The implications of the observed beam loss and particle rate on ISIS operation and MICE data taking is discussed.

• A. Kurup
  Imperial College of Science and Technology, Department of Physics, London
• A. Kurup
  Fermilab, Batavia

The COherent Muon to Electron Transition (COMET) experiment aims to measure muon to electron conversion with an unprecedented sensitivity of less than 1 in 10 million billion. The COMET experiment was given stage 1 approval by the J-PARC Program Advisory Committee in July 2009 and work is currently underway towards preparing a technical design report for the whole experiment. The need for this sensitivity places several stringent requirements on the beamline, such as, a pulsed proton beam with an extinction level between pulses of 9 orders of magnitude; a 5T superconducting solenoid operating near a high radiation environment; precise momentum selection of a large emittance muon beam and momentum selection and collimation of a large emittance electron beam. This paper will present the current status of the various components of the COMET beamline.

• J. Pasternak, L.J. Jenner, Y. Uchida
  Imperial College of Science and Technology, Department of Physics, London
• R.J. Barlow
  UMAN, Manchester
• K.M. Hock, B.D. Muratori
  Cockcroft Institute, Warrington, Cheshire
• D.J. Kelliher, S. Machida, C.R. Prior
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• Y. Kuno, A. Sato
  Osaka University, Osaka
• A. Kurup
  Fermilab, Batavia
• J.-B. Lagrange, Y. Mori
  KURRI, Osaka
• M. Lancaster
  UCL, London
• S.A. Martin
  FZJ, Jülich
• C. Ohmori
  KEK/JAEA, Ibaraki-Ken
• J. Pasternak
  STFC/RAL, Chilton, Didcot, Oxon
• S.L. Smith
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• H. Witte, T. Yokoi
  JAI, Oxford

The next generation of lepton flavour violation experiments will use high intensity and high quality muon beams. Such beams can be produced by sending a short proton pulse to the pion production target, capturing pions and performing RF phase rotation on the resulting muon beam in an FFAG ring, which was proposed for the PRISM project. A PRISM task force was created to address the accelerator and detector issues that need to be solved in order to realise the PRISM experiment. The parameters of the initial proton beam required and the PRISM experiment are reviewed. Alternative designs of the PRISM FFAG ring are presented and compared with the reference design. The ring injection/extraction system, matching with the solenoid channel and progress on the ring's main hardware systems like RF and kicker magnet are discussed. The activity on the simulation of a high sensitivity experiment and the impact on physics reach is described. The progress and future directions of the study are presented in this paper.

• J. Pasternak, M. Aslaninejad
  Imperial College of Science and Technology, Department of Physics, London
• J.S. Berg
  BNL, Upton, Long Island, New York
• D.J. Kelliher, S. Machida
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• J. Pasternak
  STFC/RAL, Chilton, Didcot, Oxon
• H. Witte
  JAI, Oxford

Nonscaling FFAG is required for the muon acceleration in the Neutrino Factory, which baseline design is under investigation in the International Design Study (IDS-NF). In order to inject/extract the muon beam with a very large emittance, several strong kickers with a very large aperture are required distributed in many lattice cells. Once the sufficient orbit separation is obtained by the kickers, the final degree of separation from the lattice is made by the septum, which needs to be superconducting. The geometry of the symmetric solutions allowing to inject/extract both signs of muons is presented. The preliminary design of the kicker and septum magnets is given.

• J.K. Pozimski, M. Aslaninejad, C. Bontoiu
  Imperial College of Science and Technology, Department of Physics, London
• J.S. Berg
  BNL, Upton, Long Island, New York
• S.A. Bogacz
  JLAB, Newport News, Virginia
• S. Machida
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon

The IDS study showed that a Neutrino Factory seems to be the most promising candidate for the next phase of high precision neutrino oscillation experiments. A part of the increased precision is due to the fact that in a Neutrino Factory the decay of muons produces a neutrino beam with narrow energy distribution and divergence. The effect of beam loading on the energy distribution of the muon beam in the Neutrino Factory has been investigated numerically. The simulations have been performed using the baseline accelerator design including cavities for different number of bunch trains and bunch train timing. A detailed analysis of the beam energy distribution expected is given together with a discussion of the energy spread produced by the gutter acceleration in the FFAG and the implications for the neutrino oscillation experiments will be presented.

• M.A. Rayner, J.H. Cobb
  OXFORDphysics, Oxford, Oxon

The Muon Ionization Cooling Experiment is one lattice section of a cooling channel suitable for conditioning the muon beam at the front end of a Neutrino Factory or Muon Collider. Scintillating fibre spectrometers and 50 ps resolution timing detectors provide the unprecedented opportunity to measure the initial and final six-dimensional phase space vectors of individual muons. The capability of MICE to study the evolution of muon beams through a solenoidal lattice will be described.

• P. Hodgson, C.N. Booth, P.J. Smith
  Sheffield University, Sheffield

The MICE experiment requires a beam of low energy muons to demonstrate muon cooling. A target mechanism has been developed that inserts a small titanium target into the circulating ISIS beam during the last 2ms before extraction. The target mechanism has been in operation in the ISIS beam during 2009 and a large set of useful data has been obtained describing the target's operational parameters. This has allowed the commissioning of the initial section of the MICE beam line and instrumentation, and the close monitoring of target performance. This work describes these target parameters and presents some of the results from operational shifts.

• P. Hodgson, C.N. Booth, P.J. Smith
  Sheffield University, Sheffield
• J.S. Tarrant
  STFC/RAL, Chilton, Didcot, Oxon

The MICE experiment uses a beam of low energy muons to test the feasibility of ionisation cooling. This beam is derived parasitically from the ISIS accelerator at the Rutherford Appleton Laboratory. A target mechanism has been developed and deployed that rapidly inserts a small titanium target into the circulating proton beam immediately prior to extraction without undue disturbance of the primary ISIS beam. The first target drive was installed in ISIS during 2008 and operated successfully for over 100,000 pulses. A second upgraded design was installed in 2009 and is currently in operation. The technical specification for this upgraded design is given and the motivation for many of the improvements is discussed. In addition possible future improvements to the current design are discussed.

• A.D. Bross, S. Geer, V.D. Shiltsev
  Fermilab, Batavia
• H.G. Kirk
  BNL, Upton, Long Island, New York
• Y. Torun
  IIT, Chicago, Illinois
• M.S. Zisman
  LBNL, Berkeley, California

An accelerator complex that can produce ultra-intense beams of muons presents many opportunities to explore new physics. A facility of this type is unique in that, in a relatively straightforward way, it can present a physics program that can be staged and thus move forward incrementally, addressing exciting new physics at each step. At the request of the US Department of Energy's Office of High Energy Physics, the Neutrino Factory and Muon Collider Collaboration and the Fermilab Muon Collider Task Force have recently submitted a proposal to create a Muon Accelerator Program that will have, as a primary goal, to deliver a Design Feasibility Study for an energy-frontier Muon Collider after a 7 year R&D program. This paper presents a description of a Muon Collider facility with a brief physics motivation, gives an overview of the proposal with respect to its organization and timeline and then discusses in some detail its major technical components.

• M. Chung, A. Jansson, A. Moretti, A.V. Tollestrup, K. Yonehara
  Fermilab, Batavia
• A. Kurup
  Imperial College of Science and Technology, Department of Physics, London

To demonstrate the feasibility of a high pressure RF cavity for use in the cooling channel of a muon collider, an experimental setup that utilizes 400-MeV Fermilab linac proton beam has been developed. In this paper, we describe the beam diagnostics and the collimator system for the experiment, and report the initial results of the beam commissioning. The transient response of the cavity to the beam is measured by the electric and magnetic pickup probes, and the beam-gas interaction is monitored by the optical diagnostic system composed of a spectrometer and two PMTs.

• M. Chung, A. Jansson, A.V. Tollestrup, K. Yonehara
  Fermilab, Batavia
• Z. Insepov
  ANL, Argonne

Ionization cooling is a critical building block for the realization of a muon collider. To suppress breakdown in the presence of the external magnetic field, an idea of using an RF cavity filled with high pressure hydrogen gas is being considered for the cooling channel design. In the high pressure RF cavity, ionization energy loss and longitudinal momentum recovery can be achieved simultaneously. One possible problem expected in the high pressure RF cavity is, however, the dissipation of significant RF power through the electrons accumulated inside the cavity. The electrons are generated from the beam-induced ionization of the high pressure gas. To characterize this detrimental loading effect, we develop a simplified model that relates the electron density evolution and the observed pickup voltage signal in the cavity, with consideration of several key molecular processes such as the formation of the polyatomic molecules and ions, excitation, recombination and electron attachment. This model is expected to be compared with the actual beam test of the cavity in the MuCool Test Area (MTA) of Fermilab.

• D.V. Neuffer
  Fermilab, Batavia
• M. Martini, G. Prior
  CERN, Geneva
• C.T. Rogers
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• C. Y. Yoshikawa
  Muons, Inc, Batavia

We discuss the design of the muon capture front end of a neutrino factory and present studies of variations of its components. In the front end, a proton bunch on a target creates secondary pions that drift into a capture transport channel, decaying into muons. A sequence of rf cavities forms the resulting muon beams into strings of bunches of differing energies, aligns the bunches to (nearly) equal central energies, and initiates ionization cooling. The cooling section uses absorber material (reducing the 3-D muon momenta) alternating with rf cavities (restoring longitudinal momentum) within strong focusing magnetic fields. The design is affected by limitations on accelerating gradients within magnetic fields. The effects of gradient limitations are explored, and mitigation strategies are presented. Variations of the ionization cooling and acceleration scenarios and extensions toward use in a muon collider are discussed.

• K. Yonehara, M. Chung, A. Jansson, A. Moretti, M. Popovic, A.V. Tollestrup
  Fermilab, Batavia
• M. Alsharo'a, R.P. Johnson, M. Notani
  Muons, Inc, Batavia
• D. Huang
  IIT, Chicago, Illinois
• Z. Insepov
  ANL, Argonne
• T. Oka, H. Wang
  University of Chicago, Chicago, Illinois
• D. Rose
  Voss Scientific, Albuquerque, New Mexico

A high pressurizing hydrogen gas filled RF cavity has a great potential to apply for muon colliders. It generates high electric field gradients in strong magnetic fields with various conditions. As the remaining demonstration, it must work under high radiation conditions. A high intensity muon beam will generate a beam-induced electron swarm via the ionization process in the cavity. A large amount of RF power will be consumed into the swarm. We show the recent non-beam test and discuss the electron swarm dynamics which plays a key role to develop a high pressure RF cavity.

• M.A.C. Cummings
  Muons, Inc, Batavia
• D. Hedin
  Northern Illinois University, DeKalb, Illinois

Muon Colliders produce high rates of unwanted particles near the beams in the detector regions. Previous designs have used massive shielding to reduce these backgrounds, at a cost of creating dead regions in the detectors. To optimize the physics from the experiments, new ways to instrument these regions are needed. Since the last study of a muon collider detector in the 1990s, new types of detectors, such as solid state photon sensors that are fine-grained, insensitive to magnetic fields, radiation-resistant, fast, and inexpensive have become available. These can be highly segmented to operate in the regions near the beams. We re-evaluate the detector design, based on new sensor technologies. Simulations that incorporate conditions in recent muon collider interaction region designs are used to revise muon collider detector parameters based on particle type and occupancy. Shielding schemes are studied for optimization. Novel schemes for the overall muon collider design, including "split-detectors", are considered.

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

A helical cooling channel (HCC) consisting of a pressurized gas absorber imbedded in a magnetic channel that provides solenoidal, helical dipole and helical quadrupole fields has shown considerable promise in providing six-dimensional cooling for muon beams. The energy lost by muons traversing the gas absorber needs to be replaced by inserting RF cavities into the HCC lattice. Replacing the substantial muon energy losses using RF cavities with reasonable gradients will require a significant fraction of the channel length be devoted to RF. However to provide the maximum phase space cooling and minimum muon losses, the HCC should have a short period and length. In this paper we examine an approach where each HCC cell has an RF cavity imbedded in the aperture with the magnetic coils are split allowing for half of the cell length to be available for the RF coupler and other services.

• C. Y. Yoshikawa, C.M. Ankenbrandt
  Muons, Inc, Batavia
• D.V. Neuffer
  Fermilab, Batavia

Intense muon beams have many potential applications, including neutrino factories and muon colliders. However, muons are produced as tertiary beams, resulting in diffuse phase space distributions. To make useful beams, the muons must be rapidly cooled before they decay. An idea conceived recently for the collection and cooling of muon beams, namely, the use of a Quasi-Isochronous Helical Channel (QIHC) to facilitate capture of muons into RF buckets, has been developed further. The resulting distribution could be cooled quickly and coalesced into a single bunch to optimize the luminosity of a muon collider. After a brief elaboration of the QIHC concept, some recent developments are described.

• M.S. Zisman
  LBNL, Berkeley, California
• J.C. Gallardo
  BNL, Upton, Long Island, New York

A Neutrino Factory requires an intense and highly cooled (in transverse phase space) muon beam. We discuss a hybrid approach for a linear 4D cooling channel consisting of high-pressure gas-filled RF cavities –potentially allowing high gradients without breakdowns– and discrete LiH absorbers to provide the necessary energy loss that results in the needed muon beam cooling. We report simulations of the channel performance and its comparison with the vacuum case; we also discuss the various technical and safety issues associated with cavities filled with high-pressure hydrogen gas. Even with additional windows that might be needed for safety reasons, the channel performance is comparable to that of the original, all-vacuum Feasibility Study 2a channel on which our design is based. If tests demonstrate that the gas-filled RF cavities can operate properly with an intense beam of ionizing particles passing through them, our approach would be an attractive way of avoiding possible breakdown problems with a vacuum RF channel.

• S.S. Kurennoy, A.J. Jason, H.M. Miyadera
  LANL, Los Alamos, New Mexico

We propose a high-gradient linear accelerator for accelerating low-energy muons and pions in a strong solenoidal magnetic field. The acceleration starts immediately after collection of pions from a target by solenoidal magnets and brings muons to a kinetic energy of about 200 MeV over a distance of the order of 10 m. At this energy, both an ionization cooling of the muon beam and its further acceleration in a superconducting linac become feasible. The project presents unique challenges ' a very large energy spread in a highly divergent beam, as well as pion and muon decays ' requiring large longitudinal and transverse acceptances. One potential solution incorporates a normal-conducting linac consisting of independently fed 0-mode RF cavities with wide apertures closed by thin metal windows or grids. The guiding magnetic field is provided by external superconducting solenoids. The cavity choice, overall linac design considerations, and simulation results of muon acceleration are presented. While the primary applications of such a linac are for homeland defense and industry, it can provide muon fluxes high enough to be of interest for physics experiments.

• H.M. Miyadera, A.J. Jason, S.S. Kurennoy
  LANL, Los Alamos, New Mexico

Many groups are working on muon accelerators for future neutrino factory and muon colliders. One of the applications of muon accelerator is muon radiography which is a promising method to investigate large objects taking advantage of the long penetration lengths of muons. We propose a compact muon accelerator that has a large energy and a phase acceptance to capture relatively low energy pion/muon of 10 - 100 MeV and accelerates them to 200 MeV without any beam cooling. Like an RFQ, mixed buncher/acceleration mode provides phase bunching during the acceleration. Our current design uses 805 MHz zero-mode normal-conducting cavities with 35 MV/m peak field*. The normal conducting cavities are surrounded by superconducting coils that produce 5 T focusing field. We ran Monte Carlo simulations to optimize linac parameters such as frequency and acceleration gradient. Muon energy loss and scattering effects at the cavity windows are studied, too. The simulation showed that about 10 % of the pion/muon injected into the linac can be accelerated to 200 MeV. Further acceleration is possible with superconducting linac.

* S. Kurennoy et al., IPAC 2010.

• F.H. O'Shea, J.B. Rosenzweig
  UCLA, Los Angeles, California
• G. Andonian
  RadiaBeam, Marina del Rey

One of the challenges of the proposed muon collider is the beam size at the interaction region. The current target for the beta function (beta-star) is 10mm for the 1.5TeV scenario with a beam emittance of 25mm-mrad. In this paper, we describe the design and development of a final focusing scheme that attempts to reach these parameters. The final focus scheme is based on the use of permanent magnet quadrupoles (PMQ) in a triplet configuration. Initial simulations show that the PMQs reach gradients as high as ~990T/m using Praseodymium based magnets in a Halbach style arrangement. Possible methods for tuning the PMQs at the interaction region, via temperature control and high-resolution movers, are also described.

• K.T. McDonald
  PU, Princeton, New Jersey
• J.R.J. Bennett
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• O. Caretta, P. Loveridge
  STFC/RAL, Chilton, Didcot, Oxon
• A.J. Carroll, V.B. Graves, P.T. Spampinato
  ORNL, Oak Ridge, Tennessee
• I. Efthymiopoulos, F. Haug, J. Lettry, M. Palm, H. Pereira
  CERN, Geneva
• A. Fabich
  EBG MedAustron, Wr. Neustadt
• H.G. Kirk, H. Park, T. Tsang
  BNL, Upton, Long Island, New York
• N.V. Mokhov, S.I. Striganov
  Fermilab, Batavia
• P.H. Titus
  PPPL, Princeton, New Jersey

We report on the analysis of data collected in the MERIT experiment at CERN during the Fall of 2007. These results validate the concept of a free mercury jet inside a high-field solenoid magnet as a target for a pulsed proton beam of 4-MW power, as needed for a future Muon Collider and/or Neutrino Factory.

• L. Coney
  UCR, Riverside, California
• A.J. Dobbs
  Imperial College of Science and Technology, Department of Physics, London
• Y. Karadzhov
  Sofia University St. Kliment Ohridski, Faculty of Physics, Sofia

The Muon Ionization Cooling Experiment (MICE) is being built at the Rutherford Appleton Laboratory (RAL) to test ionization cooling of a muon beam. Successful demonstration of cooling is a necessary step along the path toward creating future high intensity muon beams in either a Neutrino Factory or Muon Collider. Production of particles in the MICE beamline begins with a titanium target dipping into the ISIS proton beam. The resulting pions are captured, momentum-selected, and fed into a 5T superconducting decay solenoid which contains the pions and their decay muons. Another dipole then selects the final particles for propagation through the rest of the MICE beamline. Within the last year, the MICE target has been redesigned, rebuilt, and has begun operating in ISIS. The decay solenoid has also become operational, dramatically increasing the number of particles in the MICE beamline. In parallel, particle identification detectors have also been installed and commissioned. In this paper, the commissioning of the improved MICE beamline and target will be discussed, including the use of Time-of-Flight detectors to understand the content of the MICE beam between 200 and 444 MeV/c.

• P. Snopok, G.G. Hanson
  UCR, Riverside, California

A significant reduction in the six-dimensional emittance of the initial beam is required in any proposed Muon Collider scheme. Two lattices based on the original RFOFO ring design representing different stages of cooling are considered. One is the so-called open cavity lattice addressing the problem of the 201.25 MHz RF cavities running in a magnetic field, the other one is the 805 MHz RF lattice that is used for smaller emittances. The details of the acceptance analysis and tracking studies of both channels are presented and compared to the independent ICOOL implementation.

• P. Snopok, L. Coney
  UCR, Riverside, California
• A. Jansson
  Fermilab, Batavia
• C.T. Rogers
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon

In the Muon Ionization Cooling Experiment (MICE), muons are cooled by ionization cooling. Muons are passed through material, reducing the total momentum of the beam. This results in a decrease in transverse emittance and a slight increase in longitudinal emittance, but overall reduction of 6D beam emittance. In emittance exchange, a dispersive beam is passed through wedge-shaped absorbers. Muons with higher energy pass through more material, resulting in a reduction in longitudinal and transverse emittance. Emittance exchange is a vital technology for a Muon Collider and may be of use for a Neutrino Factory. Two ways to demonstrate emittance exchange in the straight solenoidal lattice of MICE are discussed. One is to let a muon beam pass through a wedge shaped absorber; the input beam distribution must be carefully selected to accommodate chromatic aberrations in the solenoid lattice. Another approach is to use the input beam for MICE without beam selection. In this case no polynomial weighting is involved; however, a more sophisticated shape of the absorber is required to reduce longitudinal emittance.

• V.S. Morozov
  ODU, Norfolk, Virginia
• S.A. Bogacz
  JLAB, Newport News, Virginia
• D. Trbojevic
  BNL, Upton, Long Island, New York

Recirculating linear accelerators (RLA) are the most likely means to achieve the rapid acceleration of short-lived muons to multi-GeV energies required for Neutrino Factories and TeV energies required for Muon Colliders. In the work described here, a novel arc optics based on a Non Scaling Fixed Field Alternating Gradient (NS-FFAG) lattice is developed, which would provide sufficient momentum acceptance to allow multiple passes (two or more consecutive energies) to be transported in one string of magnets. We present a combination of the non-scaling NS-FFAG RLA placed in a straight section. Orbit offsets of different energy muons are kept small in the NS-FFAG arcs during multiple passes. The NS-FFAG, made of densely packed FODO cells, allows momentum acceptance of dp/p=±60%. This solution would reduce overall cost and simplify the operation. Difference in a muon path length for corresponding energies is corrected with a chicane. We will also discuss technical requirements to allow the maximum number of passes by using an adjustable path length to accurately control the returned beam phase to synchronize with the RF.

• F. Antoniou
  National Technical University of Athens, Zografou
• M. Martini, Y. Papaphilippou, A. Vivoli
  CERN, Geneva

Due to the high bunch density, the output emittances of the CLIC Damping Rings (DR) are strongly dominated by the effect of Intrabeam Scattering (IBS). In an attempt to optimize the ring design and using classical IBS formalisms and approximations, the scaling of the extracted emittances and IBS growth rates is being studied, with respect to several ring parameters including energy, bunch charge, optics and wiggler characteristics. Results from the simulations using a multi-particle tracking code are also presented.

• S. Guiducci, M.E. Biagini
  INFN/LNF, Frascati (Roma)

A new baseline parameter set has been proposed for the ILC with a reduction by a factor 2 in the number of bunches. This option will allow for a corresponding factor 2 decrease in the Damping Ring circumference, with significant cost savings. A low emittance lattice for a 3.2 km long damping ring has been designed, with the same racetrack layout of the present reference 6.4 km long lattice and similar straight sections. The technical work done for the longer ring can be easily applied to the shorter one. The lattice is based on an arc cell design adopted for the SuperB collider and allows some flexibility in tuning emittance and momentum compaction.

• T. Abe, T. Kageyama, H. Sakai, Y. Takeuchi, K. Yoshino
  KEK, Ibaraki

A damping ring of positron beams is under consideration for the upgrade of KEKB (SuperKEKB) because low emittance of beams injected to the main rings is required by the SuperKEKB optics in the nano-beam scheme. We present the design of the RF accelerating structure, especially on the higher-order-mode (HOM) damped structure. This structure is based on the normal-conducting accelerating cavity system ARES, which has successful records of the long-term stable operations so far with low trip rates at KEKB. All the HOM absorbers are made of silicon carbide, bullet-shaped, and to be directly water cooled, so that the structure presented in this paper can be also a prototype for accelerating beams of the order of 10A in the SuperKEKB main ring in the high-current scheme.

• D. Wang, J. Gao, Y. Wang
  IHEP Beijing, Beijing

In this paper, we made a new design for ILC 3.2 km damping ring with 2 arcs based on FODO cell and 2 straight sections which are nearly the same as the new version of the 6.4 km ring DCO4. This new lattice uses less dipoles and quadrupoles than the present SuperB like lattice and has an adequate aperture for the large injected emittance of the positron beam. The work of lattice design and DA optimization will be presented in detail.

• Y. Papaphilippou, F. Antoniou, M.J. Barnes, S. Bettoni, S. Calatroni, P. Chiggiato, R. Corsini, A. Grudiev, R. Maccaferri, M. Modena, L. Rinolfi, G. Rumolo, D. Schoerling, D. Schulte, M. Taborelli, A. Vivoli
  CERN, Geneva
• E.B. Levichev, S.V. Sinyatkin, P. Vobly, K. Zolotarev
  BINP SB RAS, Novosibirsk

The CLIC damping rings should produce the ultra-low emittance necessary for the high luminosity performance of the collider. This combined to the high bunch charge present a number of beam dynamics and technical challenges for the rings. Lattice studies have been focused on low emittance cells with optics that reduce the effect Intra-beam scattering. The final beam emittance is reached with the help of super-conducting damping wigglers. Results from recent simulations and prototype measurements are presented, including a detailed absorption scheme design. Collective effects such as electron cloud and fast ion instability can severely limit the performance and mitigation techniques have been identified and tested. Tolerances for alignment and technical system design such as kickers, RF cavities, magnets and vacuum have been finally established.

• A. Vivoli, M. Martini
  CERN, Geneva

The CLIC 3 TeV nominal design requires very low emittance of the electron and positron beams to be reached in the damping rings. Due to low energy and to relatively high bunch charge and ultra-low emittance, Intra-Beam Scattering (IBS) effect is very strong and an accurate calculation is needed to check if the required emittance is effectively reached. For this reason it is being developed at CERN a new Software for IBS and Radiation Effects (SIRE), which simulates the evolution of the beam particle distribution in the damping rings, taking into account radiation damping, IBS and quantum excitation. In this paper we present the results of our simulations performed with SIRE on the current lattice of the CLIC damping rings.

• M. Böge, M. Aiba, A. Lüdeke, N. Milas, A. Streun
  PSI, Villigen

The application of various optics correction techniques at the SLS allows to reduce the vertical emittance to <3 pm.rad corresponding to an emittance coupling of <0.05 %. Beam sizes can be measured with a resolution of ~0.5 um allowing to resolve vertical beam sizes close to the quantum radiation limit of 0.55 pm.rad. The application of beam-based alignment/ calibration techniques on magnet girders (remotely controlled), quadrupoles and sextupoles can be used to center the beam in all relevant optical elements at a minimum expense of vertical dipole corrector strength. Furthermore a fast orbit feedback based on a high resolution digital BPM system allows to stabilize the closed orbit up to ~90 Hz and to perform precise orbit manipulations within this bandwidth. Furthermore the top-up operation mode guarantees very stable conditions for the various beam-based measurements. These conditions make the SLS an excellent "test-bed" for future damping ring optimization.

• O.B. Malyshev
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• N.A. Collomb, J.M. Lucas, S. Postlethwaite
  STFC/DL, Daresbury, Warrington, Cheshire
• M. Korostelev
  The University of Liverpool, Liverpool
• A. Wolski
  Cockcroft Institute, Warrington, Cheshire
• K. Zolotarev
  BINP SB RAS, Novosibirsk

A vacuum vessel design of wiggler sections should meet a few challenging specification. The SR power of about 40 kW is generated in each wiggler. Expanding fan of SR radiation reaches the beam vacuum chamber walls in the following wiggler and may cause the following problem: massive power dissipation on vacuum chamber walls inside the cryogenic vessel, radiation damage of superconducting coil, high photo-electron production rate that cause an e-cloud build-up to unacceptable level. Therefore this power should be absorbed in the places where these effects are tolerable or manageable. A few possible solutions for tackling all SR related problems as well as vacuum design are discussed in the paper in details.

• O.B. Malyshev
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire

Ion induced pressure instability is a potential problem for the ILC positron damping ring (DR)if the chosen pumping scheme does not provide sufficient pumping. The ion induced pressure instability effect results from ionisation of residual gas molecules by the beam particles, their acceleration in the field of the beam towards the vacuum chamber walls, causing ion induced gas desorption from vacuum chamber walls; these gas molecules in their turn can also be ionised, accelerated and cause further gas desorption. If the pumping is insufficient, this effect may cause a pressure instability, in which the pressure in the beam chamber grows rapidly to an unacceptable level. To analyse the ion induced pressure instability in the ILC positron DR the energy gained by ions was calculated for the appropriate beam parameters; it was found that the energy gain of ions will be about 300 eV. The ion induced gas desorption was estimated, and pumping solutions to avoid the ion induced pressure instability are suggested. The cheapest and most efficient solution is to use NEG coated vacuum chamber.

• O.B. Malyshev
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• N.A. Collomb, J.M. Lucas, S. Postlethwaite
  STFC/DL, Daresbury, Warrington, Cheshire
• M. Korostelev
  The University of Liverpool, Liverpool
• A. Wolski
  Cockcroft Institute, Warrington, Cheshire
• K. Zolotarev
  BINP SB RAS, Novosibirsk

A 374-m long wiggler section is a key part of ILC damping ring that should alloy reaching a low beam emittance for the ILC experiment. Synchrotron radiation generated by the beam in the wigglers should be absorbed by different components of vacuum vessel, including specially designed absorbers. The optimisation of the mechanical design, vacuum system and anti-e-cloud mitigation requires accurate calculation of the SR power distribution. The angular power distribution from a single wiggler was calculated with in-house developed software. Then the superposition of SR from all wigglers allows calculating power distribution for all components along the wiggler section and the downstream straight section.

• M. Korostelev, O.B. Malyshev, A. Wolski
  Cockcroft Institute, Warrington, Cheshire
• N.A. Collomb, J.M. Lucas, S. Postlethwaite
  STFC/DL, Daresbury, Warrington, Cheshire
• A.J.P. Thorley
  The University of Liverpool, Liverpool

The longitudinal wake fields have been calculated by using 3D code, CST Particle Studio, for a number of different vacuum chamber components of the 6.4 km ILC damping ring design. Based on the results, studies of bunch lengthening and single-bunch instabilities have been carried out. Bunch lengthening from a particle tracking code are compared with results from numerical solution of the Haissinski equation. The tracking code is used to predict the threshold for single-bunch instabilities.

• M. Korostelev, A. Wolski
  Cockcroft Institute, Warrington, Cheshire

A new lattice design for the ILC damping ring has been developed since the beginning of 2008 as a lower cost alternative to the previous OCS6 design. The lattices for the electron and positron damping rings are identical, and are designed to provide an intense, 5 GeV beam with low emittance at extraction. The latest design, presented in this paper, provides sufficient dynamic aperture for the large positron beam at injection. The lattice also meets the engineering requirements for arrangement of the positron ring directly above the electron ring in the same tunnel, using common girders for the magnets in the two rings, but with the beams circulating in opposite directions.

• M.T.F. Pivi, L. Wang
  SLAC, Menlo Park, California
• C.M. Celata, M.A. Furman, M. Venturini
  LBNL, Berkeley, California
• J.A. Crittenden, G. Dugan, M.A. Palmer
  CLASSE, Ithaca, New York
• T. Demma, S. Guiducci
  INFN/LNF, Frascati (Roma)
• K.C. Harkay
  ANL, Argonne
• O.B. Malyshev
  Cockcroft Institute, Warrington, Cheshire
• K. Ohmi, K. Shibata, Y. Suetsugu
  KEK, Ibaraki
• Y. Papaphilippou, G. Rumolo
  CERN, Geneva

As part of the International Linear Collider (ILC) collaboration, we have compared the electron cloud effect for different Damping Ring designs respectively with 6.4 km and 3.2 km circumference and investigated the feasibility of a shorter damping ring with respect to the electron cloud build-up and related beam instability. These studies were carried out with beam parameters of the ILC Low Power option. A reduced damping ring circumference has been proposed for the new ILC baseline design and would allow to considerably reduce the number of components, wiggler magnets and costs. We also briefly discuss the plans for future studies including the luminosity upgrade option with shorter bunch spacing, the evaluation of mitigations and the integration of the CesrTA results into the Damping Ring design.

• S.J. Brooks
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon

The neutrino factory requires a source of pions within a momentum window determined by the ‘muon front end' accelerator structure downstream. The technique of finding which parts of a large target block are net absorbers or emitters of particles may be adapted with this momentum window in mind. Therefore, analysis of a hadronic production simulation run using MARS15 can provide a candidate target shape in a single pass. However, changing the shape of the material also affects the absorption/emission balance, so this paper investigates iterative schemes to find a self-consistent optimal, or near-optimal, target geometry.

• J.-L. Fernandez-Hernando
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• J. Resta-López
  JAI, Oxford

Beryllium is being considered as an option material for the CLIC energy collimators in the Beam Delivery System. Its high electrical and thermal conductivity together with a large radiation length compared to other metals makes Beryllium an optimal candidate for a long tapered design collimator that will not generate high wakefields, which might degrade the orbit stability and dilute the beam emittance, and in case of the beam impacting the collimator temperature rises will not be sufficient enough to melt the metal. This paper shows results and conclusions from simulations of the impact of a CLIC bunch train hitting the collimator.

• A. Kanareykin, P. Schoessow
  Euclid TechLabs, LLC, Solon, Ohio
• S. Baturin
  LETI, Saint-Petersburg
• R. Tomás
  CERN, Geneva

In this presentation, dielectric collimator concepts for the linear collider will be described. Cylindrical and planar dielectric collimator designs for CLIC and ILC parameters will be presented, and results of simulations to minimize the beam impedance will be discussed. The prototype collimator system is planned to be fabricated and experimentally tested at Facilities for Accelerator Science and Experimental Test Beams (FACET) at SLAC.

• H.G. Kirk
  BNL, Upton, Long Island, New York
• J.J. Back
  University of Warwick, Coventry
• C.J. Densham, P. Loveridge
  STFC/RAL, Chilton, Didcot, Oxon
• X.P. Ding
  UCLA, Los Angeles, California
• V.B. Graves
  ORNL, Oak Ridge, Tennessee
• F. Ladeinde, Y. Zhan
  SUNY SB, Stony Brok, New York
• K.T. McDonald
  PU, Princeton, New Jersey

We outline a program of engineering design and simulation for a target station and pion production/capture system for a 4-MW proton beam at the front end of a Muon Collider or a Neutrino Factory. The target system consists of a free liquid-metal (nominally mercury) jet immersed in a high-field solenoid magnet capture system that also incorporates the proton beam dump. Topics to be studied include optimization of proton beam and jet target parameters, of the magnetic configuration for capture and subsequent transport of pions and muons, of the beam dump, of the radiation/thermal shielding of the capture magnets, and of the beam windows.