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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 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.

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.

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.

Accelerator-driven systems (ADS) are being considered for their potential use in the transmutation of radioactive waste. The performance of such hybrid nuclear systems depends to a large extent on the specification and reliability of high power accelerators, as well as the integration of the accelerator with spallation targets and sub-critical systems. At present, much R&D work is still required in order to demonstrate the desired capability of the system as a whole.Accelerator scientists and reactor physicists from around the world gathered at an NEA workshop to discuss issues of common interest and to present the most recent achievements in their research. Discussions focused on accelerator reliability; target, window and coolant technology; sub-critical system design and ADS simulations; safety and control of ADS; and ADS experiments and test facilities. These proceedings contain the technical papers presented at the workshop as well as summaries of the working group discussions held. They will be of particular interest to scientists working on ADS development as well as on radioactive waste management issues in general.

The Radio-Frequency Quadrupole Test Stand (RFQ-TS) was prepared for conditioning the spare RFQ in the Japan Proton Accelerator Research Complex (J-PARC) linac. Additionally, the RFQ-TS is used for the development of accelerator components and the acquisition of beam parameters. The digital feedback system of the Low-Level RF in the RFQ-TS previously used the discontinued cPCI system, which had been in use for 20 years since its development. In order to continue improvements of the RFQ-TS and to allow for future development, the system has been upgraded to use a micro telecommunications computing architecture.4 - based system, which can be developed further. This paper reports the details of the upgrade, along with the feedback and feedforward adjustments.

The muon linac has been developed at J-PARC to accelerate muons from thermal energy (25 meV) to 212 MeV using electrostatic extraction and four different types of radio-frequency cavities: RFQ, IH-DTL, DAW-CCL, and disk-loaded structures. Although some of the technologies employed were relatively novel, most proof-of-principle demonstrations have been successfully completed through prototype testing and actual production. Based on these experiences, it has become possible to propose a shorter or more efficient schematic design derived from the current design. In this poster, the new schematic design will be presented.

In J-PARC Linac, some beam dumps are used for beam conditioning and study. A beam window is installed in the beam line of the beam dump. In 2018, a beam study using a 0- degree beam dump in the Linac resulted in damage to the beam window when the beam intensity has exceeded the tolerance. So as not to repeat this experience, it was decided to immediately advance the development of a beam window protection system. The present paper describes the protection system built as an emergency measure and the tests of its performance.

Beam loss control is one of the critical tasks during the operation of high-intensity charged particle accelerators. The paper presents the concept of a nondestructive beam loss monitoring system based on beam current transformers for a linear resonance proton accelerator of the DARIA compact neutron source. Features of the practical implementation and operation of the proposed beam current transformers based on ferrite cores and the necessary preamplifier electronics using transimpedance amplifiers are considered. Particular attention is paid to the method of monitoring the difference of the measured beam currents between two successive detectors and the principles of generating an alarm signal for the implementation of a fast emergency protection system for the accelerator. Control of the current difference is implemented on the fast integration and mutual comparison of the beam pulses charge passing through the detectors which increases the accuracy of measurements, while it is possible to select several discrete values of the measured difference: for the nominal operating mode and the accelerator tuning procedure, when beam losses can increase significantly. The system works at any beam pulse repetition rate, and to prevent false block from possible interferences, the final alarm signal is generated as the sum of three consecutive signals of the comparison circuit at the beam pulse repetition rate.