Non-Destructive 3D Imaging Method Using Muonic X-Rays and a CdTe Double-Sided Strip Detector

Elemental analysis based on muonic X-rays resulting from muon irradiation provides information about bulk material composition without causing damage, which is essential in the case of precious or otherwise unreachable samples, such as in archeology and planetary science. We developed a three-dimensional (3D) elemental analysis technique by combining the elemental analysis method based on negative muons with an imaging cadmium telluride double-sided strip detector (CdTe-DSD) designed for the hard X-ray and soft γ-ray observation. A muon irradiation experiment using spherical plastic samples was conducted at the Japan Proton Accelerator Research Complex (J-PARC); a set of projection images was taken by the CdTe-DSD, equipped with a pinhole collimator, for different sample rotation angles. The projection images measured by the CdTe-DSD were utilized to obtain a 3D volumetric phantom by using the maximum likelihood expectation maximization algorithm. The reconstructed phantom successfully revealed the 3D distribution of carbon in the bulk samples and the stopping depth of the muons. This result demonstrated the feasibility of the proposed non-destructive 3D elemental analysis method for bulk material analysis based on muonic X-rays.

Neutron applications developing at compact accelerator-driven neutron sources

Neutrons have been used in a wide field of applications by using various neutron sources. Material science is one of the widest research fields. The activity is supported by nuclear research reactors and high-intensity spallation neutron sources based on a high-intensity proton accelerator. However, it is desired to perform a measurement when researchers want to do and to perform adventuresome experiments that have not yet confirmed its importance. Furthermore, trial and error measurements are necessary to improve a measurement method. Compact accelerator-driven neutron sources are suitable for such usage and in some cases can complement the measurement at a large facility. The use of the compact neutron source has sometimes led to new methods. Other than material science, a new application of soft error acceleration test has been performed at the compact accelerator-driven neutron sources. Another neutron application is radiation therapy called as boron neutron capture therapy. In this field, nuclear reactor neutron sources have been used but many of them shut down. It was desired to construct the BNCT facility near a hospital. Therefore, BNCT facilities based on the compact accelerator have been constructed in the world. Here, the neutron sources and new methods and applications developing at compact accelerator-driven neutron sources are introduced.

The High Intensity Proton Accelerator Facility

The High Intensity Proton Accelerator Facility at PSI routinely produces a proton beam with up to 1.4 MW power at a kinetic energy of 590 MeV. The beam is used to generate neutrons in spallation targets, and pions in meson production targets. The pions decay into muons and neutrinos. Pions and muons are used for condensed matter and particle physics research at the intensity frontier. This section presents the main physics and technology concepts utilized in the facility. It includes beam dynamics and the control of beam losses and activation, power conversion, efficiency aspects, and performance figures, including the availability of the facility.

The Meson Production Targets in the high energy beamline of HIPA at PSI

Two target stations in the 590 MeV proton beamline of the High Intensity Proton Accelerator (HIPA) at the Paul Scherrer Institut (PSI) produce pions and muons for seven secondary beamlines, leading to several experimental stations. The two target stations are 18 m apart. Target M is a graphite target with an effective thickness of 5 mm, Target E is a graphite wheel with a thickness of 40 mm or 60 mm. Due to the spreading of the beam in the thick target, a high power collimator system is needed to shape the beam for further transport. The beam is then transported to either the SINQ target, a neutron spallation source, or stopped in the beam dump, where about 450 kW beam power is dissipated. Targets, collimators and beam dumps are described.

Dependence of charge-exchange efficiency on cooling water temperature of a beam transport line

The 3-GeV Rapid Cycling Synchrotron at the Japan Proton Accelerator Research Complex supplies a high-intensity proton beam for neutron experiments and to the Main Ring synchrotron. Various parameters are monitored to achieve a stable operation, and it was found that the oscillations of the charge-exchange efficiency and cooling water temperature were synchronized. We evaluated the orbit fluctuations at the injection point using a beam current of the injection dump, which is proportional to the number of particles that miss the foil and fail in the charge exchange, and profile of the injection beam. The total width of the fluctuations was approximately 0.072 mm. This value is negligible from the user operation viewpoint as our existing beam position monitors cannot detect such a small signal deviation. This displacement corresponds to a 1.63 × 10− 5 variation in the dipole magnetic field. Conversely, the magnetic field variation in the L3BT dipole magnet, which was estimated by the temperature change directly, is 4.08 × 10− 5. This result suggested that the change in the cooling water temperature is one of the major causes of the efficiency fluctuation.

Developments of a multiplexer system for the High-Brilliance Neutron Source HBS

The High-Brilliance Neutron Source project (HBS) aims at developing a medium-flux accelerator-driven neutron source based on a 70 MeV, 100 mA proton accelerator. The concept optimizes the facility such that it provides high-brilliance neutron beams for instruments operating at different time structures. This can be realized by generating an interlaced proton pulse structure, which is unraveled and sent to three different target stations by a multiplexer system. In the following we present the developments of a multiplexer system at the JULIC accelerator at Forschungszentrum Jülich GmbH (FZJ), which serves as test facility for HBS. The main components of the JULIC multiplexer system are designed to be scalable to the HBS parameters.

100-MeV KOMAC Proton Accelerator at Gyeongju: Operational Status and Upgrade Plan

In 2012, the Korea Multi-purpose Accelerator Complex (KOMAC) facility with a total construction budget of about $300M was constructed at Gyeongju in Korea. It has a 75 m long 100 MeV proton accelerator, which can supply the highest average beam current of 1.6 mA. Since 2013, the KOMAC has been operating the 100 MeV proton accelerator for the official user beam service with two multi-purpose beamlines, one at 20 MeV and the other at 100 MeV. In 2015, the first new high-flux beamline was constructed for a medical isotope production, and the second new beamline was added in 2016 to provide a low-flux proton beam irradiation service mainly for research on the effects of radiation on semiconductors, spacecraft parts, and medical/biological samples. By the help of recent increased usages of Korean semiconductor manufacturing companies, such as SAMSUNG and SK hynix, the competition rate for requesting beam time of the proton accelerator was increased as high as 3.54:1 in 2020. To support various research fields with good user satisfaction, we have been preparing to increase the beam energy of the proton accelerator from 100 MeV to at least 500 MeV. In this article, we describe the construction history, current operational status, and various applications of the KOMAC proton accelerator and its future upgrade plan.

A multi-technique tomography-based approach for non-invasive characterization of additive manufacturing components in view of vacuum/UHV applications: preliminary results

In this paper, we have studied an additively manufactured metallic component, intended for ultra-high vacuum application, the exit-snout of the MACHINA transportable proton accelerator beam-line. Metal additive manufacturing components can exhibit heterogeneous and anisotropic microstructures. Two non-destructive imaging techniques, X-ray computed tomography and Neutron Tomography, were employed to examine its microstructure. They unveiled the presence of porosity and channels, the size and composition of grains and intergranular precipitates, and the general behavior of the spatial distribution of the solidification lines. While X-ray computed tomography evidenced qualitative details about the surface roughness and internal defects, neutron tomography showed excellent ability in imaging the spatial density distribution within the component. The anisotropy of the density was attributed to the material building orientation during the 3D printing process. Density variations suggest the possibility of defect pathways, which could affect high vacuum performances. In addition, these results highlight the importance of considering building orientation in the design for additive manufacturing for UHV applications. Graphical Abstract

Structural Energy Distribution and Particle Phase Stability Study of Longitudinal Dynamics of a Simple Linear Proton Accelerator

This paper presents the study of longitudinal beam dynamics of a simple linear proton accelerator and simulation results for a model linear accelerator (LINAC) using MATLAB. The study part of the transition energy, particle acceleration, transit time factor, RF factor, and momentum compaction are discussed. For the simulation, the model LINAC is built using unit cells and the unit cell consists of Quadrupole doublet and acceleration cavity. Model LINAC’s basic setup is present and the simulation is based on the single-particle analysis. The robustness of the model LINAC tested to operate varying different parameters like initial arrival phase and input energy. The criteria to measure the robustness of the model LINAC are to check the kinetic energy at the end of the LINAC and the transverse stability of the transfer matrices of each cell. The paper also presents the theoretical analysis of phase stability at both below and above transition energy. The stability of small and larger amplitude oscillations are present and simulation results for different particles each starting with different amplitudes observed, where the large amplitude oscillation falls outside of the separatrix.