04 Hadron Accelerators

A15 High Intensity Accelerators

Paper	Title	Page
THXG01	SNS Progress, Challenges and Upgrade Options	2892
	S. Henderson ORNL, Oak Ridge, Tennessee
	The talk describes the progress of SNS towards 1 MW, includes discussion of the challenges of successfully running high power superconducting pulsed proton linacs, and also looks forward to upgrade programmes.
	Slides
THXG03	Upgrades to ISIS for the New Second Target Station	2902
	J. W.G. Thomason STFC/RAL/ISIS, Chilton, Didcot, Oxon
	The new ISIS Second Target Station (TS-2) represents a major enhancement of the capabilities of the successful ISIS spallation neutron source, and correspondingly major enhancements have had to be made to the accelerator systems. As well as providing an outline of the new target station itself, the talk will describe the new dual harmonic RF system for the ISIS synchrotron which significantly increases the accelerated beam current to meet the needs of TS-2, and also the new proton beam transport line which diverts one out of every five pulses from the synchrotron to TS-2. In addition, the talk will summarise the substantial upgrades that have had to be made elsewhere on the ISIS accelerator system to underpin operation for at least another fifteen years, and will address possible future upgrades.
	Slides
THPP072	Extinction Monitor by Using a Dissociation of Hydrogen Molecule to Atoms with High Energy Proton Beam	3527
	I. Itahashi, M. Aoki, Y. Arimoto, Y. Kuno, A. Sato, M. Y. Yoshida Osaka University, Osaka
	In a recent high current accelerator technology there are so many reasons for resulting in unwanted or hallow beam to be coped with, such as resonance crossing, space charge induced emittance growth and so on. For an extinction for bunched beam of less than 10-7 order we need a particular scheme to diminish unwanted and hallow beam generated at not only spatial plane but also at longitudinal plane. In particular, the beam extinction between beam bunch is crucial for delayed coincidence measurements of intensity frontier and high sensitivity experiment such as muon to electron conversion and muon to electron gamma. The new detection method for the extinction is proposed by using a collision dissociation between a high energy proton with more than GeV energy and molecular ions. One path collision of high energy beam for molecular ion beam to be separated into atoms as well as its collision between stored molecular ions and high energy particles could be exploited for the monitor.
THPP073	Performance of the SNS Front End and Warm Linac	3530
	A. V. Aleksandrov, C. K. Allen, S. M. Cousineau, V. V. Danilov, J. Galambos, J. A. Holmes, D.-O. Jeon, T. A. Pelaia, M. A. Plum, A. P. Shishlo, M. P. Stockli, Y. Zhang 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 60 Hz repetition rate with 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The 2.5 MeV 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. With the completion of beam commissioning, the accelerator complex began operation in June 2006 and beam power is being gradually ramped up toward the design goal. Operational experience with the injector and linac will be presented including chopper performance, longitudinal beam dynamics study, and the results of a beam loss study.
THPP074	Optimal Design of a High Current MEBT with Chopper	3533
	A. V. Aleksandrov ORNL, Oak Ridge, Tennessee
	Many existing and proposed projects require a certain temporal structure imposed on the beam pulse, e.g., creating gaps for low-loss extraction from a circular accelerator. Usually it is achieved using chopper systems. In order to reduce average beam power on the target and simplify kicker requirements chopper system is located in a lower energy part of the accelerator, typically in the medium energy transport line (MEBT) between the RFQ and the linac. Many of the MEBT layouts, proposed and in use, look very much alike and try to achieve a compromise between two opposing requirements of providing strong transverse focusing and sufficiently long empty drifts for the kickers. As a result, both requirements are not fully satisfied leading to space charge induced emittance increase and very challenging technical specifications for the kicker and its power supply. These difficulties quickly increase with the beam current. We propose a different MEBT layout, which does not compromise quality of beam transport and allows space for a kicker with any reasonable parameters. A generic design of a 5.5m long MEBT transporting 100mA with emittance increase of less than 5% is shown as an example.
THPP075	Beam Dynamics of the IFMIF-EVEDA RFQ	3536
	M. Comunian, A. Pisent, P. A. Posocco INFN/LNL, Legnaro, Padova E. Fagotti Consorzio RFX, Euratom ENEA Association, Padova
	The IFMIF project is aimed at the realization of an intense neutron beam facility for testing the irradiation of the materials to be used for fusion reactors. EVEDA (Engineering Validation Engineering Design Activities) is a first step towards the implementation of this challenging project and consists of the construction of prototypes of the main units. In particular INFN-LNL is in charge of the construction of a 5 MeV, 125 mA, deuteron RFQ at 175 MHz. In this article the main aspects of the beam dynamics design of this RFQ are described, namely the optimization of the length and the transmission issues, the main outcomes and comparison of the PARMTEQM and TOUTATIS codes used for the simulations and the basic aspects of the errors studies.
THPP077	The IFMIF-EVEDA Accelerator Activities	3539
	A. Mosnier CEA, Gif-sur-Yvette A. Facco INFN/LNL, Legnaro, Padova A. Ibarra CIEMAT, Madrid
	The International Fusion Materials Irradiation Facility (IFMIF) aims at producing an intense flux of 14 MeV neutrons, in order to characterize materials envisaged for future fusion reactors. This facility is based on two high power CW accelerator drivers, each delivering a 125 mA deuteron beam at 40 MeV to the common lithium target. In the framework of the EU-JA Bilateral Agreement for the Broader Approach for Fusion, the Engineering Validation and Engineering Design Activities (EVEDA) phase of IFMIF has been launched in the middle of 2007. The objectives of EVEDA are to produce the detailed design of the entire IFMIF facility, as well as to build and test a number of prototypes, including a high-intensity CW deuteron accelerator (125 mA @ 9 MeV). The major components and subsystems will be designed and developed in Europe, and will be then assembled and operated at Rokkasho in Japan. The individual components are developed in Spain, Italy and France and an european accelerator team has been settled for the coordination of the accelerator activities. The design and the layout of the accelerator are presented as well as the development schedule.
THPP078	IFMIF-EVEDA RFQ Design	3542
	A. Pisent, M. Comunian, E. Fagotti, A. Palmieri, P. A. Posocco, C. Roncolato INFN/LNL, Legnaro, Padova F. Grespan Università degli Studi di Milano, Milano A. Pepato INFN- Sez. di Padova, Padova
	The RFQ of IFMIF-EVEDA project is characterized by very challenging specifications, with 125 mA of deuteron accelerated up to 5 MeV. After the long period of conceptual and comprehensive design of IFMIF accelerator, the decision of the construction of its low energy part has implied a new analysis of the RFQ design. In particular the beam dynamics design has been optimized, with a consistent reduction of the structure length and power consumption, and improvement of the performances in terms of beam losses. The resonator, of four vanes kind, has been designed taking advantage of the theoretical background and experimental experience gained in Europe with IPHI and TRASCO projects. The mechanical design has been analysed considering different approaches, involving vacuum brazing, laser or e'beam welding.
THPP080	A Superconducting CH-Linac for IFMIF	3548
	H. Podlech, A. Bechtold, M. Busch, F. Dziuba, H. Klein, H. Liebermann, U. Ratzinger, R. Tiede, C. Zhang IAP, Frankfurt am Main
	The IFMIF accelerator which has to provide a 40 MeV 250 mA Deuteron beam requires a duty cycle of 100%. The IAP Frankfurt has proposed 175 MHz H-type drift tube linac consisting of an IH-cavity and a chain of superconducting CH-cavities. A superconducting CH-prototype cavity has been tested very successfully and reached effective gradients of 7 MV/m. Two rf power couplers are necessary to feed one CH-cavity. The maximum rf power per cavity is approximately 500 kW. As amplifiers the originally foreseen 1 MW tubes or 300 kW tubes can be used. The focusing scheme in the CH-linac is based on superconducting solenoids. Beam dynamics simulations have been performed with an error analysis using the LORASR code based on the KONUS dynamics. An updated and improved linac design will be presented. A contribution of IAP for the EVEDA phase could consists of the construction and the test of the room temperature IH-cavity and the first complete CH cryo-module. A study together with industry has been already performed regarding the production process and the system integration of auxiliary equipment like couplers and tuner.
THPP082	Residual Activity Induced by High-energy Heavy Ions in Stainless Steel and Copper	3551
	I. Strasik, I. Hofmann, E. Kozlova, E. Mustafin GSI, Darmstadt L. N. Latysheva, N. Sobolevskiy RAS/INR, Moscow M. Pavlovic STU, Bratislava A. Smolyakov ITEP, Moscow
	The activation of accelerator structures due to beam loss is already intensity limiting problem for existing (SNS or RHIC) and planned (LHC or FAIR) hadron facilities. While beam-losses of 1 W/m are recognized as a tolerable beam-loss level for proton machines, the beam-loss tolerances for high-power heavy-ion accelerators have not yet been quantified. In this work the residual activity was calculated by Monte-Carlo particle transport codes and compared with experimental data. Simulations were performed for projectiles from proton to uranium. Experiments were performed with uranium ions at 120, 500 and 950 MeV/u irradiating copper and stainless steel targets. It was found that the isotope inventory contributing over 90% to the total activity does not depend on the projectile species, it depends only on the target material and projectile energy. This allowed establishing a scaling law for induced activity as a function of ion mass. The activity per nucleon induced by ion scales down with increasing ion mass. For example, 1 GeV/u uranium ion induces 5-times less activity per nucleon compared to 1 GeV proton. The beam-loss criteria for different projectile species are presented.
THPP083	Megawatt Upgrades for the ISIS Facility	3554
	J. W.G. Thomason, D. J. Adams, D. J.S. Findlay, I. S.K. Gardner, B. Jones, A. P. Letchford, S. J. Payne, B. G. Pine, A. Seville, C. M. Warsop, R. E. Williamson STFC/RAL/ISIS, Chilton, Didcot, Oxon D. C. Plostinar, C. R. Prior, G. H. Rees STFC/RAL/ASTeC, Chilton, Didcot, Oxon
	ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Presently, it runs at beam powers of 0.2 MW, with upgrades in place to supply increased powers for the new Second Target Station due to start operation in autumn 2008. This paper outlines schemes for major upgrades to the facility in the megawatt regime, with options for 1, 2 and 5 MW. The ideas centre around new 3.2 GeV RCS designs that can be employed to increase the energy of the existing ISIS beam to provide powers of ~1 MW or, possibly as a second upgrade stage, accumulate and accelerate beam from a new 0.8 GeV linac for 2-5 MW beams. Summaries of ring designs are presented, along with studies and simulations to assess the key loss mechanisms that will impose intensity limitations. Important factors include injection, RF systems, instabilities, longitudinal and transverse space charge.
THPP084	Discussion on RCS versus AR on the Basis of J-PARC Beam Commissioning for Pulsed Spallation Neutron Source	3557
	Y. Yamazaki KEK/JAEA, Ibaraki-Ken M. Kinsho JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
	Over a decade it is one of the most controversial issues regarding the accelerator scheme choice whether RCS or AR should be chosen for the pulsed spallation neutron source. In order to simplify the discussion, we compare 3-GeV RCS with 1-GeV AR. The former is J-PARC scheme while the latter is SNS scheme. To summarize the discussion, RCS technology is much more difficult than AR technology, although RCS has many advantages over AR arising from its low beam current for the same beam power. Now, the J-PARC 3-GeV RCS was actually commissioned. On the basis of its experience, the discussion will be resumed.
THPP085	Status of the SNS Ring Power Ramp Up	3560
	M. A. Plum, A. V. Aleksandrov, C. K. Allen, S. M. Cousineau, V. V. Danilov, J. Galambos, J. A. Holmes, D.-O. Jeon, T. A. Pelaia, A. P. Shishlo, Y. Zhang ORNL, Oak Ridge, Tennessee
	Beam was first circulated in the SNS ring in January 2006. Since that time we have been working to raise the beam power to the design value of 1.4 MW. In general the power ramp up has been proceeding very well, but several issues have been uncovered. Examples include poor transmission of the waste beams in the injection dump beam line, cross-plane coupling in the ring to target beam transport line, and higher-than-expected peak densities in the ring to target transport. In this paper we will discuss these issues and present an overall status of the ring and the transport beam lines.
FRYAGM01	Upgrade Issues for the CERN Accelerator Complex	3734
	R. Garoby CERN, Geneva
	The Large Hadron Collider at CERN is at a very advanced stage of construction and the first beam collisions in the experiments are expected during the year 2008. Work has now started for maximizing its physics reach and for preparing for other foreseeable needs. Beyond upgrades in the LHC itself, mainly in the optics of the insertions, the injector complex has to be renewed to deliver beam with upgraded characteristics with a high reliability. In a first phase, a new 160 MeV H- linac (“Linac4”) will be built to replace the present 50 MeV proton linac (Linac2) and extensive consolidation will be made. In a second phase, the present 26 GeV PS and its set of injectors (Linac2 + PSB) are planned to be replaced with a ~50 GeV synchrotron (“PS2”) using a 4 GeV superconducting proton linac (“SPL”) as injector. The SPS itself will also be the subject of major improvements, to be able to cope with a 50 GeV injection energy and with beams of much higher brightness. These proposals are described as well as their potential to evolve and fit the needs of future facilities for radioactive ions and/or neutrinos.
	Slides