EPAC 2006 - Classification:04 Hadron Accelerators/A15 High Intensity Proton Machines

04 Hadron Accelerators

A15 High Intensity Proton Machines

Paper	Title	Page
MOZAPA02	Commissioning Highlights of the Spallation Neutron Source	29
	N. Holtkamp ORNL, Oak Ridge, Tennessee
	The Spallation Neutron Source (SNS) is a second generation pulsed neutron source at Oak Ridge National Laboratory. The SNS is funded by the U.S. Department of Energy's Office of Basic Energy Sciences and is dedicated to the study of the structure and dynamics of materials by neutron scattering. A collaboration composed of six national laboratories (ANL, BNL, TJNAF, LANL, LBNL, ORNL) is responsible for the design and construction of the various subsystems. With the official start in October 1998, the operation of the full facility has begun in late spring 2006 delivering a 1.0 GeV proton beam with a pulse length of approximately 700 nanoseconds on a liquid mercury target. Within the next two years a beam power of more than one MW should be achieved. The multi-lab collaboration provided a large variety of expertise in order to enhance the beam power delivered by the accelerator by almost an order of magnitude compared to existing neutron facilities. The SNS linac consists of a room temperature and superconducting (sc) structures and is the first pulsed high power sc linac in the world. The compressor ring and the target are the final subsystems that were commissioned during early 06.
	Transparencies
MOPCH103	SPIRAL2 RFQ Prototype – First Results	282
	R. Ferdinand, R. Beunard, V. Desmezières, M. Di Giacomo, P. Robillard GANIL, Caen A.C. Caruso INFN/LNS, Catania S. Cazaux, M. Desmons, A. France, D. Leboeuf, O. Piquet, J.-C. Toussaint CEA, Gif-sur-Yvette M. Fruneau, Y. Gómez-Martínez LPSC, Grenoble
	The SPIRAL2 RFQ has been designed to accelerate a 5 mA deuteron beam (Q/A=1/2) or a 1 mA particle beam with q/A=1/3 up to 0.75 MeV/A at 88MHz. It is a CW machine which has to show stable operation, provide the required availability and reduce losses to a minimum in order to minimize the activation constraints. Extensive modelisation was done to ensure a good vane position under RF. The prototype of this 4-vane RFQ has been built and tested in INFN-LNS Catania and then in IN2P3-LPSC Grenoble. It allowed us to measure the vacuum quality, the RF field by X-ray measurements, the cavity displacement and the real vane displacement during the RF injection. Different techniques were used, including an innovative and effective CCD measurement with a 0.6 μm precision. This paper outlines the different results.
MOPCH105	A New RF Tuning Method for the End Regions of the IPHI 4-vane RFQ	285
	O. Delferriere, M. Desmons, A. France CEA, Gif-sur-Yvette R. Ferdinand GANIL, Caen
	The 3-MeV High Intensity Proton Injector (IPHI) RFQ is constituted by the assembly of three 2-m-long segments. The tuning of the end regions of such an accelerator with respect to the quadrupole mode is generally made by machining the thickness of the end plates. The dipole modes are moved away from the accelerator mode frequency by adding dipole rods and adjusting their length. In the case of the last IPHI RFQ segment, the tuning range given by possible plate thickness was not sufficient to adjust the frequency at 352 Mhz without modifying the notch depth, leading to serious engineering problems for the cooling, new thermo-mechanical simulations and drawings. To avoid these difficulties, a new way has been investigated by replacing the end plate thickness adjustment by a "quadrupole rod" length adjustment. These rods are situated between the beam axis and the dipole rods, and the tuning range is largely increased. The paper will describe this method applied to the IPHI RFQ and some experimental results obtained on the cold model.
MOPCH106	An Innovative Method to Observe RFQ Vanes Motion with Full-scale RF Power and Water Cooling	288
	A. France, O. Piquet CEA, Gif-sur-Yvette R. Ferdinand GANIL, Caen
	The design of high current RFQs is heavily strained by thermo-mechanical considerations, which eventually have an impact on machining costs, cooling systems, etc. A 1-meter long copper prototype of the SPIRAL2 RFQ has been specifically built to corroborate design options. An innovative method has been developed, allowing real-time observation of mechanical deformations of RFQ vanes, with full-scale RF power and water cooling. Digital images are acquired by a CCD camera, and processed by a dedicated software. Processing includes contrast stretching, low-pass filtering, and block-correlation followed by interpolation. Sub-pixel relative motions of RFQ electrode ends are clearly detected and measured, with RMS errors of the order of 0.6 microns.
MOPCH107	Tuning Procedure of the 6 Meter IPHI RFQ	291
	O. Piquet, M. Desmons, A. France CEA, Gif-sur-Yvette
	In the framework of the IPHI project (High Intensity Proton Injector), the RFQ cavity is divided into 6 sections of 1 meter each, and assembled in 3 segments separated by coupling plates. We will present the tuning procedure of the aluminium RFQ cold model to set the accelerating mode frequency, a flat voltage profile and to minimize the dipole components of the accelerating voltage. This tuning procedure can be divided in three steps. First, dipole mode frequencies are adjusted with rods for the 3 separated segments. Second, RFQ end cells and coupling cells are tuned by mechanical machining of tuning plates. Third, using a fully automated bead-pull for the measurement of the field distribution inside every RFQ quadrants, the RFQ is tuned with 96 plungers in a small number of iterations. Tuning this 6-meter long cold model is a comprehensive training in view of the future tuning of the copper RFQ with the variable voltage profile.
MOPCH108	Error Study of LINAC 4	294
	M.A. Baylac, J.-M. De Conto, E. Froidefond LPSC, Grenoble E.Zh. Sargsyan CERN, Geneva
	Within the framework of the Joint Research Activity HIPPI (High Intensity Pulsed Proton Injector) of the CARE program, the conception study of the LINAC 4 accelerator which aims to intensify the proton flux available for the CERN injection line is pursued. The linac, operating in pulsed mode at 352 MHz, is designed to accelerate a 65 mA beam of H^- ions up to an energy of 160 MeV. The requirements on acceptable beam emittance growth and particle loss are extremely tight. In order to determine the Drift Tube Linac tolerances, we examined the sensitivity of the LINAC 4 DTL to errors on the accelerating field and the focusing quadrupoles. Simulations were performed with the transport code TRACEWIN (CEA-Saclay, France). We will present results on individual sensitivities to a single error as well as the global impact of alignment and RF errors on the beam quality. Similarly, accelerating structures following the DTL in the LINAC4 design (CCDTL, SCL) have been studied.
MOPCH109	Design Studies on a Novel Stellarator Type High Current Ion Storage Ring	297
	M. Droba, N.S. Joshi, O. Meusel, P. Nonn, U. Ratzinger IAP, Frankfurt-am-Main
	A high current storage ring for the accumulation of ion beams provided by a new 150 kV terminal is under consideration at the Frankfurt University. The configuration based on a toroidal magnetic field seems promising for the storage of intense low energy ion beams, especially when concerning the various potential concepts for space charge compensation. The theory of plasma confinement on magnetic surface is transformed to numerical simulations on circulating ion beams. The space charge effects and stability conditions are studied and will be presented. Various injection techniques based on crossed field-drifts are investigated. Accordingly test experiments are prepared based on two 30 degree toroidal sectors at a major radius of 1.3m with a maximum toroidal magnetic field of 0.6T on axis.
MOPCH111	A Fast Beam Chopper for the RAL Front End Test Stand	300
	M.A. Clarke-Gayther CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon G. Bellodi, F. Gerigk CERN, Geneva
	The FETS project at RAL will test a fast beam chopper, designed to address the requirements of high power proton drivers for next generation pulsed spallation sources and neutrino factories. A description is given of the novel RAL 'Fast - Slow' chopping scheme, and of candidate optical designs for the 3.0 MeV, 60 mA, H^- Medium Energy Beam Transport (MEBT) line.
MOPCH112	The RAL Front End Test Stand	303
	A.P. Letchford, M.A. Clarke-Gayther, D.C. Faircloth, D.C. Plostinar, J.K. Pozimski CCLRC/RAL, Chilton, Didcot, Oxon J.J. Back University of Warwick, Coventry Y.A. Cheng, S. Jolly, A. Kurup, P. Savage Imperial College of Science and Technology, Department of Physics, London
	High power proton accelerators (HPPAs) with beam powers in the megawatt range have many possible applications including drivers for spallation neutron sources, neutrino factories, waste transmuters and tritium production facilities. These applications typically propose beam powers of 5 MW or more compared to the highest beam power achieved from a pulsed proton accelerator in routine operation of 0.16 MW at ISIS. The UK's commitment to the development of the next generation of HPPAs is demonstrated by a test stand being constructed in collaboration between RAL, Imperial College London and the University of Warwick. The aim of the RAL Front End Test Stand is to demonstrate that chopped low energy beams of high quality can be produced and is intended to allow generic experiments exploring a variety of operational regimes. This paper describes the status of the RAL Front End Test Stand which consists of five main components: a 60 mA H^- ion source, a low energy beam transport, a 324 MHz Radio Frequency Quadrupole accelerator, a high speed beam chopper and a comprehensive suite of diagnostics. The aim is to demonstrate production of a 60 mA, 2 ms, 50 pps, chopped H^- beam at 3 MeV.
MOPCH113	Re-bunching RF Cavities and Hybrid Quadrupoles for the RAL Front-end Test Stand (FETS)	306
	D.C. Plostinar CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon M.A. Clarke-Gayther CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
	The proposed FETS project at RAL will test a fast beam chopper in a 3.0 MeV H^- Medium Energy Beam Transport (MEBT) line. Space restrictions in the MEBT line place constraints on component length and drive the requirement to identify compact component configurations. A description is given of candidate re-bunching RF cavities and hybrid quadrupole designs. The cavity options considered are the space efficient Drift Tube Linac type cavity (DTL) with integrated quadrupoles, and the high shunt impedance Coupled Cavity Linac type cavity (CCL) with external quadrupoles. The advantages and disadvantages of both structures are discussed and a comprehensive comparison between the two is made enabling the best cavity geometry choice. The compact hybrid quadrupole configurations considered are the 'tandem' combination of permanent magnet (PMQ) and electro-magnetic (EMQ) types, and the concentric combination of PMQ and laminar conductor (Lambertson) EMQ types.
MOPCH114	Progress on Dual Harmonic Acceleration on the ISIS Synchrotron	309
	A. Seville, D.J. Adams, D. Bayley, N.E. Farthing, I.S.K. Gardner, M.G. Glover, A. Morris, B.G. Pine, J.W.G. Thomason, C.M. Warsop CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
	The ISIS facility at the Rutherford Appleton Laboratory in the UK is currently the most intense pulsed, spallation, neutron source. The accelerator consists of a 70 MeV H^- Linac and an 800 MeV, 50 Hz, rapid cycling, proton Synchrotron. The synchrotron beam intensity is 2.5·10¹³ protons per pulse, corresponding to a mean current of 200 μA. The synchrotron beam is accelerated using six, ferrite loaded, RF cavities with harmonic number 2. Four additional, harmonic number 4, cavities have been installed to increase the beam bunching factor with the potential of raising the operating current to 300 μA. As ISIS has a busy user schedule the time available for dual harmonic work has been limited. However, much progress has been made in the last year and encouraging results have been obtained. This paper reports on the hardware commissioning and beam tests with dual harmonic acceleration.
MOPCH115	Transverse Space Charge Studies for the ISIS Synchrotron	312
	C.M. Warsop CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
	The ISIS Facility at the Rutherford Appleton Laboratory in the UK produces intense neutron and muon beams for condensed matter research. It is based on a 50 Hz proton synchrotron which, once the commissioning of a new dual harmonic RF system is complete, will accelerate about 3.5·10¹³ protons per pulse from 70 to 800 MeV, corresponding to mean beam powers of 0.2 MW. Following this upgrade, transverse space charge is expected to be one of the main intensity limitations, and is also a key factor for further machine upgrades. A programme of R&D on transverse space charge is now under way, aiming not only to improve the ISIS ring but also to exploit it as an experimental tool for testing theory and codes. This paper summarises work so far, outlining calculations for coherent envelope modes on ISIS, using numerical solutions of the envelope equation to show the expected behaviour near half integer resonance. Progress on work linking these predictions with more realistic beam models in space charge codes, and extending calculations to images, coupling and non linear resonances will be described. Plans and preparations for experiments, along with initial results, will also be presented.
MOPCH116	Electromagnetic Design of a Radio Frequency Quadrupole for the Front End Test Stand at RAL	315
	A. Kurup Imperial College of Science and Technology, Department of Physics, London A.P. Letchford CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
	The goal of the RAL front end test stand is to demonstrate cleanly chopped bunches of a 60mA H^- ion beam at 3MeV. The acceleration of the H^- ions from 65keV to 3MeV will be done using a radio frequency quadrupole (RFQ) operating at a resonant frequency of 324MHz. The two types of RFQ considered were a 4-vane and a 4-rod. The 4-vane has a higher Q-value but the post-production adjustment is limited. The 4-rod design is easier to manufacture but requires complicated cooling at 324MHz. The results of electromagnetic simulations using CST Microwave Studio are presented for the 4-vane type and 4-rod type RFQ.
MOPCH117	Mechanical Design and RF Measurement on RFQ for Front-end Test Stand at RAL	318
	P. Savage, Y.A. Cheng Imperial College of Science and Technology, Department of Physics, London A.P. Letchford CCLRC/RAL/ISIS, Chilton, Didcot, Oxon J.K. Pozimski CCLRC/RAL, Chilton, Didcot, Oxon
	This paper will present the mechanical design and preliminary results of a RF measurement system for the cold model of a 324MHz 4-vane RFQ, which is part of the development of a proton driver front end test stand at the Rutherford Appleton Laboratory (RAL) in the UK. The design concepts will be discussed and some issues in manufacturing of the RFQ will be pointed out, and specific modifications will be explained. Furthermore, results of thermal simulations of the RFQ will be presented together with RF simulations of the resonant frequency, the Q-value and the longitudinal field distribution.
MOPCH118	Wideband Low-output-impedance RF System for the Second Harmonic Cavity in the ISIS Synchrotron	321
	Y. Irie JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken D. Bayley, G.M. Cross, I.S.K. Gardner, M.G. Glover, D. Jenkins, A. Morris, A. Seville, S.P. Stoneham, J.W.G. Thomason, T. Western CCLRC/RAL/ISIS, Chilton, Didcot, Oxon J.C. Dooling, D. Horan, R. Kustom, M.E. Middendorf, G. Pile ANL, Argonne, Illinois S. Fukumoto, M. Muto, T. Oki, A. Takagi, S. Takano KEK, Ibaraki
	Wideband low-output-impedance RF system for the second harmonic cavity in the ISIS synchrotron has been developed by the collaboration between Argonne National Laboratory, US, KEK, Japan and Rutherford Appleton Laboratory, UK. Low output impedance is realized by the feedback from plate output to grid input of the final triode amplifier, resulting in less than 30 ohms over the frequency range of 2.7 - 6.2 MHz which is required for the second harmonic cavity. The vacuum tubes in the driver and final stages are both operated in class A, and a grid bias switching system is used on each tube to avoid unnecessary plate dissipations during a non-acceleration cycle. High power test was performed with a ferrite-loaded second harmonic cavity, where the bias current was swept at 50 Hz repetition rate. The maximum voltage of 12kV peak per accelerating gap was obtained stably at earlier period of an acceleration cycle. A beam test with this system is planned at the ISIS synchrotron in order to investigate how the low impedance system works under heavy beam loading conditions, and is capable of mitigating the space charge detuning at the RF trapping stage.
MOPCH119	Present Status of the Induction Synchrotron Experiment in the KEK PS	324
	K. Takayama, Y. Arakida, T. Iwashita, T. Kono, E. Nakamura, Y. Shimosaki, M.J. Shirakata, T. Sueno, K. Torikai KEK, Ibaraki K. Otsuka Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture
	A concept of the induction synchrotron, which was proposed by Takayama and Kishiro in 2000, has been demonstrated by using the KEK PS since 2004. A proton bunch trapped in the RF bucket was accelerated with the induction acceleration devices from 500 MeV to 8 GeV, which was energized with the newly developed switching power supply. This form of the KEK PS is something like a hybrid synchrotron. In addition, the injected proton bunch was confined by the step barrier-voltages at the injection energy of 500MeV, which were generated with the same induction acceleration device. Then a concept of the induction synchrotron that a proton bunch was captured by the barrier bucket and accelerated with the induction voltage is to be fully demonstrated. K. Takayama et al. "Observation of the Acceleration of a Single Bunch by Using the Induction Device in the KEK Proton Synchrotron", Phys. Rev. Lett., 94, 144801 (2005).**K. Torikai et al. "Acceleration and Confinement of a Proton Bunch with the Induction Acceleration System in the KEK Proton Synchrotron", submitted to Phys. Rev. ST-AB (2005), KEK-Preprint 2005-80 A, December 2005.
MOPCH120	Ground Motion Study and the Related Effects on the J-PARC	327
	S. Takeda, N. Yamamoto, M. Yoshioka KEK, Ibaraki Y. Nakayama JPOWER, Kanagawa-ken
	The power spectrum density, coherence and cross-spectrum density of the ground motion in the J-PARC site are studied to get the guideline of the beam control systems. J-PARC consists of a 600 MeV linac, a 3 GeV Rapid-cycling synchrotron (RCS) and a 50 GeV synchrotron (MR). MR provides a beam current of 15 micro-A with a period of 3 sec to either the nuclear physics experimental area or the neutrino production target. MR is a very high beam power machine, so its optimum beam loss must be kept fewer than 0.01% of an accelerated beam in order to decrease the radiation damage of accelerator components and to get easy accessibilty to them. From the point of view of beam loss, we give some detailed discussion about the relation between the MR operation and the ground motion using the observed data.
MOPCH121	Ground Motion Measurement at J-PARC	330
	Y. Nakayama, K. Tada JPOWER, Kanagawa-ken S. Takeda, M. Yoshioka KEK, Ibaraki
	In the next generation accelerator, construction of the machine on the stable ground is preferable for accelerator beam operation. We have measured ground motion at the J-PARC site under construction, where the ground is very close to the Pacific Ocean. In this paper, some of the observed results are shown, comparing the results of the previous observation at some accelerator facilities and next generation accelerator candidate sites in Japan.
MOPCH122	Realistic Beam Loss Estimation from the Nuclear Scattering at the RCS Charge-exchange Foil	333
	P.K. Saha, H. Hotchi, Y. Irie, F. Noda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken H. Harada Hiroshima University, Higashi-Hiroshima
	We have developed simulation tools for the realistic beam loss estimation at the RCS(rapid cycling synchrotron) of J-PARC(Japan Proton Accelerator Research Complex). The present simulation concerns an accurate estimation of the beam loss caused by the nuclear scattering at the charge-exchange foil during the multi turn injection period. It can also figure out the loss point in the ring, so would become very useful for the maintenance and optimization as well. The simulation code GEANT together with the SAD(Strategic Accelerator Design) have been used for the present purpose. In this paper, detail simulation method including the result will be discussed.
MOPCH124	Energy Deposition in Adjacent LHC Superconducting Magnets from Beam Loss at LHC Transfer Line Collimators	336
	V. Kain, S. Beavan, Y. Kadi CERN, Geneva
	Injection intensities for the LHC are over an order of magnitude above the damage threshold. The collimation system in the two transfer lines is designed to dilute the beam sufficiently to avoid damage in case of accidental beam loss or mis-steered beam. To maximise the protection for the LHC most of the collimators are located in the last 300 m upstream of the injection point where the transfer lines approach the LHC machine. To study the issue of possible quenches following beam loss at the collimators the entire collimation section in one of the lines, TI 8, together with the adjacent part of the LHC has been modeled in FLUKA. The simulated energy deposition in the LHC for worst-case accidental losses as well as for losses expected during a normal filling is presented. The operational implications are discussed.
MOPCH126	Accelerator Research on the Rapid Cycling Synchrotron at IPNS	339
	G.E. McMichael, F.R. Brumwell, L. Donley, J.C. Dooling, W. Guo, K.C. Harkay, Q.B. Hasse, D. Horan, R. Kustom, M.K. Lien, M.E. Middendorf, M.R. Moser, S. Wang ANL, Argonne, Illinois
	The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a national user facility for neutron scattering. Neutrons are produced by 70 ns pulses of protons (~3x 10¹² protons per pulse) impacting a depleted-uranium target at a pulse repetition rate of 30 Hz. Three accelerators in series (a 750 keV Cockcroft-Walton, 50 MeV Alvarez linac accelerating H^- ions, and a 450 MeV rapid-cycling proton synchrotron) provide the beam that is directed to the target. New diagnostics and a third rf cavity that can be operated at either the fundamental or second harmonic of the ring frequency have recently been installed and an experimental program established to try to gain understanding of an instability that limits the charge-per-bunch in the RCS. This program will be described, and preliminary results presented.
MOPCH127	SNS Warm Linac Commissioning Results	342
	A.V. Aleksandrov, S. Assadi, W. Blokland, P. Chu, S.M. Cousineau, V.V. Danilov, C. Deibele, J. Galambos, S. Henderson, D.-O. Jeon, M.A. Plum, A.P. Shishlo ORNL, Oak Ridge, Tennessee
	The Spallation Neutron Source accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of an H^- injector, capable of producing one-ms-long pulses at 60Hz repetition rate with 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The 2.5MeV beam from the Front End is accelerated to 86 MeV in the Drift Tube Linac, then to 185 MeV in a Coupled-Cavity Linac and finally to 1 GeV in the Superconducting Linac. The staged beam commissioning of the accelerator complex is proceeding as component installation progresses. Current results of the beam commissioning program of the warm linac will be presented including transverse emittance evolution along the linac, longitudinal bunch profile measurements at the beginning and end of the linac, and beam loss study.
MOPCH129	Status of the SNS Beam Power Upgrade Project	345
	S. Henderson, A.V. Aleksandrov, D.E. Anderson, S. Assadi, I.E. Campisi, F. Casagrande, M.S. Champion, R.I. Cutler, V.V. Danilov, G.W. Dodson, D.A. Everitt, J. Galambos, J.R. Haines, J.A. Holmes, N. Holtkamp, T. Hunter, D.-O. Jeon, S.-H. Kim, D.C. Lousteau, T.L. Mann, M.P. McCarthy, T. McManamy, G.R. Murdoch, M.A. Plum, B.R. Riemer, M.P. Stockli, D. Stout, R.F. Welton ORNL, Oak Ridge, Tennessee
	The baseline Spallation Neutron Source (SNS) accelerator complex, consisting of an H^- injector, a 1 GeV linear accelerator, an accumulator ring and associated transport lines, will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. Upgrades to the SNS accelerator and target systems to increase the beam power to at least 2 MW, with a design goal of 3 MW, are in the planning stages. The increased SNS beam power can be achieved primarily by increasing the peak H^- ion source current from 38 mA to 59 mA, installing additional superconducting cryomodules to increase the final linac beam energy to 1.3 GeV, and modifying injection and extraction hardware in the ring to handle the increased beam energy. The mercury target power handling capability will be increased to 2 MW or greater by i) mitigating cavitation damage to the target container through improved materials/surface treatments, and introducing a fine dispersion of gas bubbles in the mercury, and ii) upgrading the proton beam window, inner reflector plug and moderators. The upgrade beam parameters will be presented and the required hardware modifications will be described.
MOPCH130	Simulations for SNS Ring Commissioning	348
	J.A. Holmes, S.M. Cousineau, S. Henderson, M.A. Plum ORNL, Oak Ridge, Tennessee
	In preparation for SNS ring commissioning, a number of operational issues have been studied using ORBIT Code simulations. These include beam injection without the use of time-dependent painting, beam accumulation and transport to the extraction dump and to the target, optimal painting schemes for various beam intensities, detailed tracking through the extraction septum with fully correct geometry, quadrupole current constraints in the ring-to-target transfer line (RTBT), and detailed modeling of H minus carbon foil stripping at injection. All these studies incorporated detailed physics including beam-foil interactions, symplectic single particle tracking, space charge and impedances, and losses due to apertures and collimation.
MOPCH131	SNS Ring Commissioning Results	351
	M.A. Plum, A.V. Aleksandrov, S. Assadi, W. Blokland, I.E. Campisi, P. Chu, S.M. Cousineau, V.V. Danilov, C. Deibele, G.W. Dodson, J. Galambos, M. Giannella, S. Henderson, J.A. Holmes, D.-O. Jeon, S.-H. Kim, C.D. Long, T.A. Pelaia, T.J. Shea, A.P. Shishlo, Y. Zhang ORNL, Oak Ridge, Tennessee
	The Spallation Neutron Source (SNS) comprises a 1.5-MW, 60-Hz, 1-GeV linac, an accumulator ring, associated beam lines, and a spallation neutron target. Construction began in 1999 and the project is on track to be completed in June 2006. By September 2005 the facility was commissioned up through the end of the superconducting linac, and in January 2006 commissioning began on the High Energy Beam Transport beam line, the accumulator ring, and the Ring to Target Beam Transport beam line up to the Extraction Beam Dump. In this paper we will discuss early results from ring commissioning including a comparison of achieved vs. design beam machine parameters and the maximum beam intensity achieved to date.
MOPCH132	Coupled Maps for Electron and Ion Clouds	354
	U. Iriso CELLS, Bellaterra (Cerdanyola del Vallès) S. Peggs BNL, Upton, Long Island, New York
	Contemporary electron cloud models and simulations reproduce second order phase transitions, in which electron clouds grow smoothly beyond a threshold from "off" to "on". In contrast, some locations in the Relativistic Heavy Ion Collider (RHIC) exhibit first order phase transition behaviour, in which electron cloud related outgassing rates turn "on" or "off" precipitously. This paper presents a global framework with a high level of abstraction in which additional physics can be introduced in order to reproduce first (and second) order phase transitions. It does so by introducing maps that model the bunch-to-bunch evolution of coupled electron and ion clouds. This results in simulations that run several orders of magnitude faster, reproduce first order phase transitions, and show hysteresis effects. Coupled maps also suggest that additional dynamical phases (like period doubling, or chaos) could be observed.
MOPCH133	An Analytic Calculation of the Electron Cloud Linear Map Coefficient	357
	U. Iriso CELLS, Bellaterra (Cerdanyola del Vallès) S. Peggs BNL, Upton, Long Island, New York
	The evolution of the electron density during multibunch electron cloud formation can often be reproduced using a bunch-to-bunch iterative map formalism. The coefficients that parameterize the map function are readily obtained by fitting to results from compute-intensive electron cloud simulations. This paper derives an analytic expression for the linear map coefficient that governs weak cloud behaviour from first principles. Good agreement is found when analytical results are compared with linear coefficient values obtained from numerical simulations. This analysis is useful in predicting thresholds beyond which electron cloud formation occurs, and thus in determining safety regions in parameter space where an accelerator can be operated without creating electron clouds. The formalism explicitly shows that the multipacting resonance condition is not a sine qua non for electron cloud formation.
MOPCH134	Electron-impact Desorption at the RHIC Beam Pipes	360
	U. Iriso, U. Iriso CELLS, Bellaterra (Cerdanyola del Vallès) W. Fischer BNL, Upton, Long Island, New York
	The electron induced molecular desorption coefficient of a material provides the number of molecules released when an electron hits its surface. This coefficient changes as a function of the material, energy of the electrons, surface status, etc. In this paper, this coefficient is inferred analyzing electron detector and pressure gauge signals during electron clouds at the Relativistic Heavy Ion Collider (RHIC) beam pipes. The evolution of the electron-impact desorption coefficient after weeks of electron bombardment is followed for both baked and unbaked stainless steel chambers, evaluating the feasibility of the scrubbing effect. Measurements of an energy spectrum during multipacting conditions are shown, and the final results are compared with laboratory simulations.
MOPCH135	Benchmarking Electron Cloud Data with Computer Simulation Codes	363
	U. Iriso CELLS, Bellaterra (Cerdanyola del Vallès) G. Rumolo CERN, Geneva
	Saturated electron flux and time decay of the electron cloud are experimentally inferred using many electron detector datasets at the Relativistic Heavy Ion Collider (RHIC). These results are compared with simulation results using two independent electron cloud computer codes, CSEC and ECLOUD. Simulation results are obtained over a range of different values for 1) the maximum Secondary Electron Yield (SEY), and 2) the electron reflection probability at zero energy. These results are used to validate parameterization models of the SEY as a function of the electron energy.
MOPCH136	China Spallation Neutron Source Accelerators: Design, Research, and Development	366
	J. Wei BNL, Upton, Long Island, New York S.X. Fang, S. Fu IHEP Beijing, Beijing
	The Beijing Spallation Neutron Source (BSNS) is a newly approved high power accelerator project based on a H^- linear accelerator and a rapid cycling synchrotron. During the past year, several major revisions were made to the design including the type of the front end, linac frequency, transport layout, ring lattice, and type of ring components. Possible upgrade paths were also laid out: based on an extension of the warm linac, the ring injection energy and the beam current could be raised doubling the beam power on target to reach 200 kW; an extension with a superconducting RF linac of similar length could raise the beam power near 0.5 MW. Based on these considerations, research and development activities are started. In this paper, we discuss the rationale of design revisions and summarize the recent work.
MOPCH137	An Anti-symmetric Lattice for High Intensity Rapid-cycling Synchrotrons	369
	J. Wei, Y.Y. Lee, S. Tepikian BNL, Upton, Long Island, New York S.X. Fang, Q. Qin, J. Tang, S. Wang IHEP Beijing, Beijing S. Machida, C.R. Prior, G. Rees CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
	Rapid cycling synchrotrons are used in many high power facilities like spallation neutron sources and proton drivers. In such accelerators, beam collimation plays a crucial role in reducing the uncontrolled beam loss. Furthermore, the injection and extraction section needs to reside in dispersion-free region to avoid couplings; a significant amount of drift space is needed to house the RF accelerating cavities; orbit, tune, and chromatic corrections are needed; long, uninterrupted straights are desired to ease injection tuning and to raise collimation efficiency. Finally, the machine circumference needs to be small to reduce construction costs. In this paper, we present a lattice designed to satisfy these needs. The lattice contains a drift created by a missing dipole near the peak dispersion to facilitate longitudinal collimation. The compact FODO arc allows easy orbit, tune, coupling, and chromatic correction. The doublet straight provides long uninterrupted straights. The four-fold lattice symmetry separates injection, extraction, and collimation to different straights. This lattice is chosen for the Beijing Spallation Neutron Source synchrotron.
MOPCH138	Choice of Proton Driver Parameters for a Neutrino Factory	372
	W.-T. Weng, J.S. Berg, R.C. Fernow, J.C. Gallardo, H.G. Kirk, N. Simos BNL, Upton, Long Island, New York S.J. Brooks CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
	A Neutrino Factory typically comprises the following subsystems: proton driver; target; muon collection and conditioning( bunching, phase rotation, and cooling); muon acceleration; and muon decay ring. It takes great effort to design each subsystem properly, such that it can mesh with all other subsystems to optimize the overall facility performance. This optimization is presently being studied as part of the International Scoping Study of a Future Neutrino Factory and Superbeam Facility. This paper will evaluate the implications of other subsystems on the parameters of a proton driver for a Neutrino Factory. At the desired power of 4 MW, the impacts of the choice of the proton energy, bunch length, bunch intensity, and repetition rate on other subsystems are assessed to identify a proper range of operation for each parameter. A suitable "design phase space" of proton driver parameters is defined. Given possible choices of design parameters for proton driver, we compare the performance of a linac, a synchrotron, and an FFAG accelerator. The relative merits of existing proton driver proposals will also be examined.
TUZAPA01	Present Status of the J-PARC Accelerator	930
	H. Kobayashi KEK, Ibaraki
	The Japan Proton Accelerator Research Complex (J-PARC) is a joint project of High Energy Accelerator Research Organization (KEK) and Japan Atomic Energy Agency (JAEA), which started on April 1, 2001. The J-PARC accelerator complex is composed of a 400 MeV proton linac, a 3 GeV Rapid-Cycling Synchrotron (RCS), and a 50 GeV Proton Synchrotron (MR). A 180-MeV beam ( in the first stage) accelerated by the linac is to be injected into the RCS, and further accelerated there to 3 GeV. The RCS will operate at 25 Hz, and will provide the Materials and Life Science Facility (MLF) with a 1-MW beam (600 kW during 180 MeV injection). There are two extraction sections in the MR: fast extraction for neutrino experiment and slow extraction for the Hadron Facility. A linac beam with a peak current of 30 mA and an energy of 19.7 MeV was successfully accelerated in Sep. 2004 using the first tank of the Drift Tube Linac in KEK. Now three accelerators are under installation. The beam commissioning of the linac will start in this December and those of the RCS and the MR will start in Sep. 2007 and May 2008, respectively. Status of installation and plan for commissioning run will be presented.
	Transparencies
TUZAPA02	ISIS Upgrades – A Status Report	935
	D.J.S. Findlay, D.J. Adams, T.A. Broome, M.A. Clarke-Gayther, P. Drumm, D.C. Faircloth, I.S.K. Gardner, P. Gear, M.G. Glover, S. Hughes, H.J. Jones, M. Krendler, A.P. Letchford, E.J. McCarron, S.J. Payne, C.R. Prior, A. Seville, C.M. Warsop CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
	Since 2002 several accelerator upgrades have been made to the ISIS spallation neutron source at the Rutherford Appleton Laboratory in the UK, and upgrades are currently continuing in the form of the Second Target Station Project. The paper reviews the upgrade programmes: a new extraction straight, replacement of the Cockcroft-Walton by an RFQ, installation of a second harmonic RF system, replacement and upgrading of installed equipment, design and installation of improved diagnostics in conjunction with beam dynamics simulations, the Second Target Station Project, design and construction of a front end test stand, and the MICE programme. The paper also looks forward to possible future schemes at ISIS beyond the Second Target Station Project.
	Transparencies
WEOBPA03	1.8 MW Upgrade of the PSI Proton Facility	1879
	P.A. Schmelzbach, S.R.A. Adam, A. Adelmann, H. Fitze, G. Heidenreich, J.-Y. Raguin, U. Rohrer, P.K. Sigg PSI, Villigen
	The PSI proton accelerator delivers currently a 590 MeV beam with an intensity of 2 mA. The upgrade programme aiming at boosting the beam power from 1.2 to 1.8 MW includes the ongoing installation of new bunchers in the transfer lines to the injector cyclotron and between injector and ring cyclotron, the replacement of the Al-cavities of the ring cyclotron by Cu-cavities operated at 1 MV, and the design and future installation of additional accelerating cavities in the injector cyclotron. Simulation studies are under way to improve our understanding of the space charge effects at the different stages of acceleration. The present status of the project will be presented.
	Transparencies