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A new study for a boron neutron capture therapy irradiation facility, based on a 2.5 MeV proton accelerator on a thick Li target as neutron converter, is presented here. The beam shaping assembly (BSA) modeling has been performed with the use of the MCNP5 Monte Carlo code. The fast (i.e., > 10 keV) neutron component yielded by the 7 Li( p , n ) 7 Be reaction is slowed down through TiF 3 neutron spectrum shifter, while to obtain a high-quality epithermal neutron beam at the beam port exit additional layers for thermal neutrons removal and shielding of gamma rays were used. Moreover, 60 Ni and Ti 6 Al 14 V were selected to filter out and further remove the residual fast neutron component, while cadmium was chosen as thermal neutrons absorber, and bismuth was selected for gamma rays shielding. The therapeutic effectiveness of the proposed BSA was evaluated by performing a set of dose-equivalent distribution calculations in a standard Snyder head phantom. The simulation results show that the proposed BSA modeling meets all the recommended by IAEA criteria and provides one possible technical choice for an accelerator-based BNCT irradiation facility in a hospital environment.

The SNS accelerator complex utilizes a front-end H− injector featuring a Cs-enhanced, RF-driven H− ion source and a compact electrostatic low-energy beam transport (LEBT). Beam extraction enhancements realised on a test stand in the past several years has significantly increased the H− injector output capability from ∼60 mA to ∼120 mA at the routine operational RF power of ∼50 kW and duty-factor of 6% (1.0 ms at 60 Hz). A beam current exceeding 150 mA was demonstrated with the RF power raised up to ∼80 kW. Additionally, a preliminary optimization of the ion source plasma filter field has further increased the beam current to 165 mA, albeit with an undesirable rise in co-extracted electron current. In the meantime, improvements to the existing electrostatic LEBT and development of a new magnetic LEBT are underway to enable robust and smooth beam transport at very high currents. These advancements are expected to provide sufficient operational margin for the SNS upgrade to 2.8 MW and to offer promising solutions for H− injectors in future multi-megawatt proton accelerators.

AbstractThe use of the digital imaging detector (DID) for calibrating the Prometeus proton accelerator before a beam therapy session is considered. The results of the DID detector operation in the mode of recording spots (low-intensity pulses), obtained during a Prometeus accelerator beam session, are presented for the first time. The DID detector makes it possible to obtain on-line the distribution of the energy release of each spot over the irradiated target region per several accelerator pulses.

The J-PARC 3 GeV Rapid-Cycling Synchrotron (RCS) delivers a high intensity proton beam to the 30 GeV Main Ring (MR). The improvement of longitudinal beam matching between RCS and MR is desired to suppress the beam loss in the MR. A scenario to improve the longitudinal beam matching between RCS and MR is designed. For the RCS, the bunch lengthening scheme using the unstable fixed point generated by the second harmonic is considered. For the MR, the RF voltage pattern is adjusted to match the longitudinal beam emittance of the RCS. The details of the scenario for improving the longitudinal beam matching between RCS and MR and the results of beam simulation studies are reported.

To develop a dedicated muon experimental area for the study of energy materials and cells using surface muons, we plan to construct the S3 experimental area on the S-line, Muon Science Establishment (MUSE), Materials and Life Science Experimental Facility (MLF), Japan Proton Accelerator Research Complex (J-PARC). To transport the beam to the sample position in the S3 area, two quadrupole triplets and a bend magnet will be used after the S1 and S2 branches. A dedicated kicker system will be used to share the beam among the branches of the S-line. Before starting construction of the S3 area, we perform the Monte Carlo simulation for the shield study and beam transportation. For the safe operation of the beamline, the required thickness and height of the iron shield of the S3 area are estimated to be 5 cm and 5 m, respectively.

A silicon strip detector has been developed for positron tracking from muon decay at the J-PARC muon g – 2/EDM experiment. The detector is composed of silicon strip sensors with a strip pitch of 190 μm and features a readout with a 200 MHz sampling clock. It can be operated at 25 Hz on the J-PARC MLF muon beam line. The application of the detector to μSR measurement at J-PARC MLF is being considered. The specifications of the detector and its prospects for μSR measurement is presented in this article.

The design of the DARIA compact neutron source based on a linear resonant proton accelerator is aimed at creating a serial installation capable of providing the Russian scientific community with pulsed neutron beams with intensities comparable to those of research nuclear reactors. The absence of fissile material makes it possible to significantly reduce the radiation-safety requirements for such installations and, consequently, to place them at the site of leading scientific centers and universities that train specialists in the field of neutron physics. Under a grant from the Ministry of Science and Higher Education of the Russian Federation, key elements of the installation are being developed. The design and sequence of manufacturing for a full-scale model of an accelerator section with radio-frequency quadrupole focusing and a cavity with a drift-tube linac are presented.

Saclay CEA/IRFU is working for the delivery of five Non-Invasive Profile Monitors in the frame of the in-kind contribution agreement signed with the European Spallation Source. Neutrons will be produced by spallation reactions of 2 GeV proton beam impinging on a Tungsten target. To accelerate protons a powerful linear accelerator of 5MW is under construction. Diagnostic devices are mandatory tools for the tuning and protection of the machine. The non-invasive profile monitors provide a measurement of the beam profile in transverse directions to the beam propagation. This project raises several physical and technical challenges including low signal detection of ions or electrons, profile distortions induced by the beam Space Charge effect and non-uniformities of electric field. Simulation and model of the critical aspects of the detector have been performed in order to prove the performance and the feasibility of the detector. A series of prototypes has been built with different readout types, and tested in real conditions at the 3MeV proton accelerator IPHI. All of them show some advantages and drawbacks revealed by the tests in real beam conditions. In this paper we present the results of the tests for the various configuration readout systems to agree with the model and simulation of the detector. In concluding remarks, we will discuss the performance of the prototypes and point out the camerabased one to be the more suitable for the final design.

In the present work, we propose to investigate the production of dNΩ in the Ω-d→pdNΩ- process by utilizing an effective Lagrangian approach, where dNΩ is identified as NΩ bound state with the binding energy Eb=2.46 MeV. Experimentally, the J-PARC hadron facility proposed to investigate the K-p→Ω-K¯(∗)0K+ process, which is expected to yield an Ω beam with the momentum of approximately 3 GeV. Additionally, theoretical studies of the ψ(2S)→Ω-Ω¯+ process at BESIII provided an Ω beam with the momentum of 774 MeV. Considering these two potential Ω beam sources, our estimations show that for the Ω-d→pdNΩ- process, the cross sections are (329.7-49.6+26.9) μ b, (174.0-38.2+26.5) μ b, (16.9-7.7+7.4) μ b, and (2.0-1.4+1.8) μ b at PΩ= 0.7, 0.9, 2.0, and 4.0 GeV, respectively, where the central values are estimated with Λr=1.0 GeV, and the errors come from the variation of Λr from 0.8 to 1.2 GeV. We also estimate the differential cross sections, which reach the maximum at the forward angle limit. In addition, since the dNΩ dibaryon predominantly decays into ΞΛ . Therefore, we further investigate the Ω-d→pΞ-Λ process and estimate the relevant cross sections. It is expected that the present estimations can be tested by further experimental measurements at J-PARC and STCF in the future.

The KOTO II experiment at J-PARC is a next-generation experiment that is under design aiming at the measurement of the branching ratio of the K L → π 0 ν ν ¯ decay. The KOTO II experiment is planned in the extended Hadron Experimental Facility at J-PARC using the second production target. With the second production target, the K L extraction angle of 5 degrees is chosen instead of 16 degrees in order to obtain a larger K L flux and harder K L momentum spectrum while keeping the same ratio of neutron and K L fluxes. To realize the extraction angle, the KOTO II detector is behind the primary beam dump. The KOTO II detector has a longer decay volume and a larger calorimeter to achieve a larger decay probability and higher acceptance of the K L decay. With the designed beam line and the detector, 40 signal events are expected for the branching ratio of 3×10 −11 with 60 background events in the running period of 3 × 10 7 s, which corresponds to approximately 5- σ discovery of the decay.