PSI, Villigen
The cyclotron based high power proton accelerator facility at PSI drives a neutron spallation source and two Meson production targets with a CW proton beam at 590MeV kinetic energy. This talk concentrates on the operational and technical aspects specific to acceleration and transport of a high power beam. Furthermore a summary on upgrade plans to increase the beam power from presently 1.2MW to 1.8MW will be given.
KEK, Ibaraki
The beam commissioning of J-PARC linac has been started since November 2006, and the initial commissioning has been completed in September 2007. Since then, the linac beam has been supplied to the succeeding RCS (Rapid Cycling Synchrotron) for its commissioning. The emphasis of the linac tuning has been shifted to the stabilization of the beam parameters, and better beam availability has gradually been required for the linac operation. On the other hand, the average beam power is rather limited because we are still in the initial commissioning stage for RCS and MR (Main Ring). The hourly average of the beam power from RCS is limited to 4 kW due to the available beam dump capacity. Accordingly, we still have little experience on the machine activation with a high-power and stable beam operation. In this regard, we are in a transitional stage for our linac from commissioning to operation. In this paper, we present the current linac performance and operational experiences obtained so far after briefly reviewing the commissioning history. Particular emphasis is put on the technical challenges we faced up to the present. Future plans to increase the beam power are also discussed.
ORNL, Oak Ridge, Tennessee
Since the start of neutron production in October of 2006, the average beam power level has increased from ~ 5 kW to over 500 kW. This increased has been realized by increases in the beam current, pulse length and repetition rate. Equipment issues encountered during this ramp-up will be discussed along with mitigation efforts. A major concern in the power ramp up has been minimization of uncontrolled beam loss. The beam loss levels, loss reduction efforts, and experience levels with residual activation will be discussed. Also the operational run cycles will be discussed, with an evolution in emphasis from beam-studies to neutron production.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
ISIS is currently the world's most productive spallation neutron source. A total beam power of ~0.2 MW is delivered by a 70 MeV H- linac and an 800 MeV rapidly cycling proton synchrotron to two target stations, one which has been running since 1984, and a second which is being commissioned this year (2008). ISIS runs for typically ~200 days each year scheduled as some five ~40-day user cycles, although shutdowns lasting several months for major maintenance and upgrade work took place in 2002, 2004 and 2007 (during user cycles ISIS runs 7 days/week, 24 hours/day, and the ~200 days excludes run-up and machine physics time). In order to enable hands-on maintenance régimes to prevail, considerable efforts are made to minimise beam losses during operations, and engineering design of accelerator and beam line components specifically includes measures to limit radiation doses to personnel. The talk will cover these issues and others, and will also describe the difficult balances to be struck between operations, maintenance and upgrade work.
LANL, Los Alamos, New Mexico
The heart of the Los Alamos Neutron Science Center (LANSCE) is a pulsed linear accelerator that is used to simultaneously provide H+ and H- beams to several user facilities. This accelerator contains two Cockcroft-Walton style injectors, a 100-MeV drift tube linac and an 800-MeV coupled cavity linac. This presentation will touch on various aspects of the high power operation including performance and limitations, tune-up strategy, beam losses and machine protection.
BNL, Upton, Long Island, New York
AGS have not operated in high intensity mode since 2001, at that time AGS was highest intensity accelerator in the word. Beam loss and residual activation were the main concern for the high intensity operations. This talk will cover beam losses and its limits as set by operational procedures to protect machine and minimize the activations.
Fermilab, Batavia, Illinois
Since January 2008 Fermilab's Main Injector has switched from 2 to 10 batch slip Stacking as an upgrade to 400 KW operation at 120 GeV. Currently the beam power has reached 350 KW and efforts are continuing in order to reach 400 KW. The current performance and the future plans for reaching 700 KW will be described.
CERN, Geneva
The Large Hadron Collider (LHC) will collide two protons beam with an energy of 7 TeV each. The stored energy and intensity exceeds the quench level of the superconducting magnets and the damage level of the machine components by far. Therefore a robust and reliable collimation system is required which controls the losses to the superconducting magnets below the quench limit and to protect the accelerator components from damage in the event of beam loss. The layout and design of the LHC collimation system is presented and the expected system performance is shown. The calculated losses around the ring were provided as input for energy deposition studies in the cleaning insertions itself but also close to experimental insertions. In addition the results from studies on proton losses originating from p-p interaction in the experiments are shown.
PSI, Villigen
The ring cyclotron at the PSI accelerator facility accelerates protons to 590MeV with a current of 2 mA at present. The stepwise increase to 3 mA is planned. During normal operation there are main beam loss points at targets, beam dumps and collimators. If the beam strikes material particles are lost due to multiple scattering. Subsequent nuclear reactions lead to the production of activated materials in the components itself and their surroundings. During shutdown radioactive components have to be removed for disposal or repair. To some extent the removal requires operations done by personnel nearby the activated components. To estimate the personal dose and to plan working procedures, a way to calculate the expected dose is essential. In addition, for later disposal of the radioactive components the nuclide inventory is required by the authorities. The Monte Carlo particle transport code MCNPX coupled to the build-up and decay codes SP-FISPACT, Orihet3 and Cinder’90, as well as the bookkeeping system PWWMBS developed at PSI, are used to calculate the required quantities. Both methods will be presented and the results are compared to measurements of different activated components.
ORNL, Oak Ridge, Tennessee
The Spallation Neutron Source accelerator is a neutron scattering facility for materials research that recently started operations and presently is in the process of power ramp-up to reach mega-watt power level within a year in cycles of operations and maintenance and tuning periods. The structural materials inside the accelerator tunnel are activated by protons beam losses and by secondary particles. Secondary particles appear due to spallation reactions caused by the proton losses, and produce the residual radiation after shut down in the tunnel environment. In order to plan maintenance work after each operations period, residual dose measurements are taking at 30 cm distance from the accelerator structures and on contact. During normal operation, beam losses and beam scenario are recorded and used as a source to calculate expected residual dose rates after shut down. Calculation analyses are performed using the transport code MCNPX followed by the activation calculation script, which uses the nuclear inventory code CINDER’90, then converting gammas production spectra and gamma power to the dose rates. Calculated results for various locations are compared with measured data.
KEK, Ibaraki
Beam commissioning of J-PARC Main Ring (MR) has been started in May, 2008. The 3-GeV beams extracted from the rapid cycling synchrotron (RCS) are injected into the MR and captured by rf, and then extracted to a 3-GeV beam dump. In this paper, we present results of the first-stage commissioning run from May to June 2008. After five months shutdown for installation of fast extraction and slow extraction devices, the second-stage commissioning run will be started in December 2008.
Fermilab, Batavia, Illinois
The NuMI beam at Fermilab has delivered almost 5x10 20 120 GeV protons to the neutrino production target, since the start for MINOS physics operation in 2005. We will report on beam operation status, including successes and challenges to date with the beam and NuMI system technical components. Also covered will be the ongoing program of increasing NuMI beam power using slip stacking of beam in the Main Injector accelerator.
ORNL, Oak Ridge, Tennessee
The paper describes a parallel flow of the Spallation Neutron Source (SNS) linac and ring commissioning and development of commissioning tools. An evolution of the physics control system, its features, problems and solutions are presented. The peculiarities of the SNS project such as a collaboration between six Department of Energy laboratories, an absence of previous experience in large accelerator construction and operation in Oak Ridge National Laboratory, an original upper level of a control system (physics applications) and their effect on SNS commissioning are discussed. SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
University of the Basque Country, Faculty of Science and Technology, Bilbao
Bilbao, Faculty of Science and Technology, Bilbao
Fundación TEKNIKER, Eibar (Gipuzkoa)
Elytt Energy, Madrid
A revised layout for the proton linear accelerator as proposed by the European Spallation Source-Bilbao (Spain) bid to host the installation is here described. The new machine concept aims to incorporate advances which have been registered within the ï¬eld of high power accelerators during the last decade. Particularly relevant are the ongoing works within Magnetic Fusion activities (IFMIF/EVEDA), waste transmutation (EUROTRANS) or radioactive ion beam (EURISOL) and heavy-ion physics (FAIR, SPIRAL2) which have lead to signiï¬cantly shorter accelerators incorporating state-of-the-art technology which mainly replaces decades-old copper drift-tubes, coupled-cavity LINACs or some other accelerating structures employed for energies beyond 50 MeV or so by superconducting cavities (SC) of a wholly new kind. The design of such a new accelerator layout will be critically dependent upon the development and/or adaptation of low β superconducting cavities already developed for some of the referred projects into those adequate for pulsed operation and high duty cycle.
The authors wish to acknowledge extremely fruitful discussions held with scientists from CEA/SACLAY, IPN/ORSAY as well as from the ISIS Spallation Neutron Source.