JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
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 with occasional linac beam studies for finer tuning. The emphasis of the linac tuning has been shifted to the characterization and stabilization of the beam parameters, and better beam availability has gradually been required for the linac operation. In this paper, we present the current linac performance and operational experience obtained so far after a brief review of the commissioning history. Remaining commissioning tasks and the future upgrade plan to increase the beam power are also discussed.
LANL, Los Alamos, New Mexico
The Los Alamos Neutron Science Center (LANSCE) accelerator is an 800 MeV proton linac that drives user facilities for isotope production, proton radiography, ultra-cold neutrons, weapons neutron research and various sciences using neutron scattering. The LANSCE Refurbishment Project (LANSCE-R) is an ambitious project to refurbish key elements of the LANSCE accelerator that are becoming obsolete or nearing end-of-life. The conceptual design phase for the project is funded and underway. The 5 year, $170M (US) project will enable future decades of reliable, high-performance operation. It will replace a substantial fraction of the radio-frequency power systems (gridded tubes and klystrons) with modern systems, completely refurbish the original accelerator control and timing systems, replace obsolete diagnostic devices, and modernize other ancillary systems. An overview of the LANSCE-R project will be presented. The functional and operating requirements will be discussed, the proposed technical solutions presented, and the plan for successful project execution while meeting annual customer expectations for beam delivery will be reviewed.
LANL, Los Alamos, New Mexico
Funding: U. S. Department of Energy, National Nuclear Security Administration, Contract No. DE-AC52-06NA25396
The Los Alamos Neutron Science Center (LANSCE) continues to be a signature experimental science facility at Los Alamos National Laboratory (LANL). The 800 MeV linear proton accelerator provides multiplexed beams to five unique target stations to produce medical radioisotopes, ultra-cold neutrons, thermal and high-energy neutrons for material and nuclear science, and to conduct proton radiography of dynamic events. Recent operating experience will be reviewed and the role of an enhanced LANSCE facility in LANL's new signature facility initiative, Matter and Radiation in Extremes (MaRIE) will be discussed.
LA-UR-08-03581
NIIEFA, St. Petersburg
AN Krylov SRI, St. Petersburg
Funding: Rosatom corp.
There are examined prospects and challengers associated with the development of low-energy electronuclear power plant eliminating any possibility of uncontrolled chain fission reaction through fission in subcritical reactor with an additional neutron source. The neutron source is anticipated to be a heavy-element target irradiated with a beam of protons accelerated to several hundreds of mega-electron-volts. The intensity of external neutron source for an electronuclear reactor rated under 200-400 MW may be much less than for greater ones, and that allows reducing accelerator performances to limits that are already run in the world industry. Potential applications of such electronuclear plants include municipal, industrial and other electricity, and heat supply utilities in remote areas. The same engineering philosophy may be used on solving of the nuclear waste transmutation problem.
Linac Systems, LLC, Albuquerque, New Mexico
A 50 kW, water-cooled conical target for producing neutrons via the Li-7(p,n)Be-7 reaction at 2.5 MeV proton energy is under development at Linac Systems. This target is intended to accept a stationary, expanded CW beam with a diameter of 8 cm directly from an rf linac, resulting in peak surface heat flux of 7.5 MW m-2 (a 'waterbag' beam power distribution is assumed). The target is predicted to meet the intensity requirements for practical accelerator-based boron neutron capture therapy (BNCT), in concert with Linac Systems' CW RFI linac. Lithium metal targets present well-known physical and mechanical challenges at high beam power density that are addressed in our design. For instance, lithium melts at 180 C, necessitating efficient removal of heat at a low ΔT relative to ambient temperature. CFD modeling indicates that with 50 kW incident beam power, the peak lithium temperature can be held below 150 C with a water flow rate near 80 l min-1 and corresponding pressure drop of 170 kPa. The target prototype has been fabricated and is undergoing experimental thermal-hydraulic testing using an electron beam at the Plasma Materials Test Facility, Sandia National Laboratory.
Kyoto ICR, Uji, Kyoto
ILL, Grenoble
RIKEN, Wako, Saitama
KEK, Ibaraki
University of Tokyo, Tokyo
JAEA, Ibaraki-ken
Kyoto University, Kyoto
ICEPP, Tokyo
We are developing a modulating permanent magnet sextupole lens to focus pulsed cold neutrons. It is based on the extended Halbach configuration to generate stronger magnetic field. In order to adjust the strength, the magnet is divided into two nested co-axial rings, where the inner ring is fixed and the outer ring can be rotated. Synchronizing the modulation with neutron beam pulse suppresses the chromatic aberration. These devices largely improve the utilization efficiency of neutrons, which makes even small linac based neutron sources practical. We have fabricated a half-scale model and studied its strength, torque and temperature rise during the operation. The main causes of the temperature rise are eddy-current loss in the poles made of soft magnetic material in inner ring and hysteresis loss. A laminated structure reduced the eddy-current loss. The temperature rise was suppressed to about half of the former model. We now study their B-H curve to optimize the thickness of the sheet. Annealing of the material is supposed to reduce the hysteresis loss, which will be tested soon. The experimental results of very-cold neutrons focusing with the half-scale model are also described.
NIIEFA, St. Petersburg
Saint-Petersburg State University, Saint-Petersburg
AN Krylov SRI, St. Petersburg
Funding: Rosatom corp.
We present results of calculations of the neutron generation processes in metal targets induced by protons with energies up to 1 GeV using GEANT4 framework. Results on the neutron yield in large targets and neutron generation as a function of target's dimensions are presented. Energy deposit in the target is also given. The obtained results are to be used for multiplying blanket ADS target design.
ORNL, Oak Ridge, Tennessee
Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
For a high intensity linac such as the SNS linac, it matters to match adequately to minimize the beam mismatch and potential beam loss. The technique of doing the matching using the wire-scanners in series was employed. It was verified that matching was improved through the matching technique based on the beam profile measurements from wire-scanners in series.
Osaka Prefecture University, Sakai
Energetic electron beams higher than several MeV occasionally induce direct nuclear reactions with the target nuclei. These processes are attributed to the quasi-elastic scattering of electrons (e,e') with the target nuclei and similar to the photo-nuclear reactions. These reactions are considered to be useful for the non-destructive analysis of heavy elements such as U and Th. In addition, a two-dimensional analysis is realized only by scanning of electron beam. On the other hand, the huge X-ray burst caused by the bremsstrahlung with the electron pulse bombardment is the most harmful phenomenon for the radiation measurement system. In this study, an ultra low intensity electron beam was used for relieving the problem, which has been developed by modifying an electron linear accelerator. The minimum beam charge about several aC/pulse has been achieved at the present. Consequently, the neutron emitted by Pb(e,e'n)Pb reaction was measured successfully by the use of the low intensity beams. The linearity between the neutron count and the concentration of Pb in the target was verified experimentally.
NSC/KIPT, Kharkov
Idaho National Laboratory, Idaho
ANL, Argonne
Today accelerator driven subcritical assembly is candidate for the next generation of energy-generating nuclear facility, which could provide safe energy production, burning of transuranium elements and transmutation of radionuclides. Use of the electron beam with particle energy up to 150-200 MeV secures several advantages. Electron linear accelerators are much cheaper compared to hadron accelerators. Homogeneous irradiation of the assembly with neutrons could be provided. NSC KIPT together with ANL develops the project of a neutron source based on the sub-critical assembly driven by electron linear accelerator. Energy of electrons is 100-200 MeV. The target and assembly design is optimized to maximize the neutron source intensity with subcriticality of 0.98. Accelerator on average beam power of 100 kW, with repetition rate up to 300 Hz and pulse duration of 3,2 ms is under development. Transportation line should provide beam transfer with minimal losses of electrons and should form homogeneous distribution of the particle density at the target. Maximal value of a neutron flux is Fm=2x1013 n/(cm2s), and power of energy release in the result of nuclei fission is Pm≈ 100 kW.
ORNL, Oak Ridge, Tennessee
ORNL RAD, Oak Ridge, Tennessee
Funding: *SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy
During the first three years, the Spallation Neutron Source is ramping up the rep rate, pulse length, and beam current to reach 1 to 1.4 MW beam power in 2009. This challenges the Front-end with the H- source designed and built by Lawrence Berkeley National Laboratory. Early in 2007, the low-energy beam transport needed to be modified to improve the availability for duty factors in excess of 0.2%. Late in 2007, the H- source needed to be modified to produce the required 25 mA LINAC beam current during the ~0.4 ms long pulses at 60 Hz. The optimistic 1.4 MW goal requires 38 mA LINAC beam current, which was demonstrated for 4 hours on 12/24/07. LBNL developed a cesium system that uses only 30 mg of Cs to minimize the risk to the adjacent electrostatic LEBT and RFQ. Improved procedures and configuration were needed to generate intense beam currents for long pulses (>0.2 ms). Now optimal beam currents are reached within eight hours of replacing the H- source. The beam decay appears to be as small as 1% per day, which is compensated by a gradual increase in rf power. The peak performance can be restored by slowly re-cesiating the converter without interupting the neutron production.
ORNL, Oak Ridge, Tennessee
The latest operational experiences of the SNS 1 GeV superconducting H- linac will be presented as the beam power is increased and losses and beam halo become more important. The talk will include a comparison of the advantages and disadvantages of superconducting cavities. For example, issues arising from the use of different sets of SC cavities at different times will be described, along with the operational consequences on emittance and halo development.
DESY, Hamburg
For more than 10 years DESY has been operating a high resolution eddy-current scanning installation with rotating table for nondestructive flaw detection on niobium sheets for SRF cavities. More than 2000 sheets have been examined up to now, several types of defects have been detected and identified using different supplementary methods such as EDX, X-ray fluorescence, neutron activation analysis etc. In order to scan Nb-sheets needed for XFEL-cavity production, new scanning devices have to be build. One option of the eddy-current installations could be an application of SQUID-sensors due to much higher sensitivity instead of conventional probes. A SQUID based scanner system was built and is in evaluation at DESY. A status report will be given.
LANL, Los Alamos, New Mexico
The Los Alamos Neutron Science Center (LANSCE) is in the conceptual design phase of a refurbishment project that will sustain reliable facility operations well into the next decade. The LANSCE accelerator was constructed in the late 1960s and early 1970s and is a national user facility that provides pulsed protons and spallation neutrons for defense and civilian research and applications. The refurbishment will focus on systems that are approaching "end of life" and systems where modern upgrades hold the promise for significant operating cost savings. The current baseline consist of replacing all the 201 MHz rf amplifiers, replacing greater than 75% of the 805 MHz rf systems with a combination of high efficiency klystrons and new klystrons of the existing style, replacing four high voltage systems, and replacing all the low level rf cavity field control systems along the accelerator. System designs and requirements will be presented and the project plan will be discussed.
ESRF, Grenoble
Synchrotron X-rays and neutrons provide unique microscopic information on the structures and dynamics of condensed matter. These probes are essential tools for biologists, chemists, physicists and materials scientists and have become increasingly important in a remarkably wide range of disciplines, from palaeontology to medicine. The electron storage rings producing synchrotron radiation, and fission reactor or spallation neutron sources, are usually situated at major national or international laboratories. Such central research facilities are exemplified by the two international laboratories in Grenoble, the European Synchrotron Radiation Facility and the Institut Laue-Langevin. After a discussion of the sources used to produce synchrotron radiation and neutron beams, some of the instrumentation and methods used in the investigation of materials will be described, with illustrative examples of recent research. Finally, some major X-ray and neutron sources under construction or at the planning stage will be described, including several where linac technology plays an important role (e.g. the XFEL at DESY and the SNS at ORNL).
TRIUMF, Vancouver
A major focus of the linac community is to develop technology in support of the ILC project. The science motivation for the ILC will be presented with reference to the particle physics programs at Fermilab and the LHC.