Table of contents

Bipolar Junction Transistors (BJTs) are widely used in the presence of ionizing radiation, such as in space or in the surroundings of nuclear reactors. For the application in these fields, the influence of Total Ionization Dose (TID) and Electromagnetic Pulse (EMP) on BJTs should be carefully considered. In this work, for the comprehension of the combined effects of TID and EMP on BJT, a numerical model of a NPN BJT (2N2222) is developed with the semiconductor device simulation software TCAD. The simulated results indicate that the TID of gamma-rays can increase the depletion layer area of the BJT and lead to a reduction of its current gain and that a negative base voltage may in these conditions cause the breakdown of the emitter junction. Therefore, the results obtained indicate that the combined TID and EMP can lower the breakdown voltage of the BJT.

In this article, we implemented a fully digital Coincidence Doppler Broadening (CDB) spectrometer consisting of two HPGe detectors, a fully digital processing and acquisition board, and a dedicated software system. The Field Programmable Gate Array (FPGA) on the board extracts energy and time stamp of digitized pulses from HPGe detectors, and communicates with the dedicated software by which the single channel spectrums and 2D coincidence spectrum were produced. We designed an instruction set dedicated to the CDB Spectrometer and the controller module in FPGA so that the FPGA subsystem is fully controllable and configurable. The trapezoidal pulse shaping algorithm was implemented in FPGA whose arguments are all configurable through the dedicated software by the instruction set. We examined the long-term stability of the spectrometer by 511 keV peak position of both channels. The 2D Gaussian fitting is performed on coincidence spectrum by the software to correct the peak drift of both channels. The results show that this method effectively improves the Doppler-broadened spectrum, by which the peak-to-background ratio increases from 7.0 × 10⁵ to 1.9 × 10⁶.

As experiments searching for neutrinoless double beta decay push into the inverted hierarchy, enriched isotope target masses of hundreds of kilograms are required. Due to unavoidable losses throughout the entire production chain, the recovery of expensive enriched material used in crystal-based experiments should be given special attention. The CUPID-0 experiment using Zn⁸²Se scintillating bolomoters provides a unique opportunity at the 10-kg-scale to test a recovery process for enriched ⁸²Se. We present a multi-stage, high-yield method consisting of wet chemistry and vacuum distillation. The chemical purity, isotopic abundance, and radiopurity is demonstrated to be preserved after the ⁸²Se extraction with recovery efficiency no less than 86.4% (that potentially can be higher than 94.7%) and chemical purity of 99.999%.

The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype.

Liquid Argon Time Projection Chamber (LArTPC) technology is commonly utilized in neutrino detector designs. It enables detailed reconstruction of neutrino events with high spatial precision and low energy threshold. Its field response (FR) model describes the time-dependent electric currents induced in the anode-plane electrodes when ionization electrons drift nearby. An accurate and precise FR is a crucial input to LArTPC detector simulations and charge reconstruction. Established LArTPC designs have been based on parallel wire planes. It allows accurate and computationally economic two-dimensional (2D) FR models utilizing the translational symmetry along the direction of the wires. Recently, novel LArTPC designs utilize electrodes formed on printed circuit board (PCB) in the shape of strips with through holes. The translational symmetry is no longer a good approximation near the electrodes and a new FR calculation that employs regions with three dimensions (3D) has been developed. Extending the 2D models to 3D would be computationally expensive. Fortuitously, the nature of strips with through holes allows for a computationally economic approach based on the finite-difference method (FDM). In this paper, we present a new software package pochoir that calculates LArTPC field response for these new strip-based anode designs. This package combines 3D calculations in the volume near the electrodes with 2D far-field solutions to achieve fast and precise field response computation. We apply the resulting FR to simulate and reconstruct samples of cosmic-ray muons and ³⁹Ar decays from a Vertical Drift (VD) detector prototype operated at CERN. We find the difference between real and simulated data within 5%. Current state-of-the-art LArTPC software requires a 2D FR which we provide by averaging over one dimension and estimate that variations lost in this average are smaller than 7%.

For accelerated productivity, and continual innovation in the field of spintronics, the electrical characterization of the magnetic tunnel junction (MTJs) is of paramount importance. This report deals with the testing of the MTJs. It focuses on the design of an experimental setup with data acquisition of the MTJs with perpendicular magnetic tunnel junctions where a high magnetic field aligned perpendicular to the film plane is required. Furthermore, devices with very small electrodes of only a few micrometers in lateral size can be tested. A computer through a LabVIEW program controls the data acquisition system.

A Forward Calorimeter (FoCal) has been proposed as part of the ALICE upgrades for data taking from 2029 onwards. The FoCal will feature a sampling electromagnetic calorimeter segmented into 110 towers supplemented by a hadron calorimeter. The electromagnetic calorimeter will be composed of 20 passive layers of tungsten absorber interleaved with 18 active layers of low-granularity silicon pad sensors and two layers of high-granularity pixel detectors. Each pad layer will be read out by 110 silicon pad sensors of 72 channels, amounting to a total of 1980 sensors. This paper describes, from front-end to back-end, the electronics developed to instrument a tower prototype composed of 18 silicon pad sensors as well as a design proposal for the full-detector readout system.

The China Spallation Neutron Source project Phase-II (CSNS-II) aims to deliver a proton beam of 500 kW on the tungsten target. To accomplish this goal, an RF-driven negative hydrogen ion source was developed to replace the penning ion source used in CSNS-I. The RF-driven ion source has been put into commissioning on CSNS accelerator since September 8^th, 2021. And it was shut down on July 26^th, 2022, together with the whole accelerator for the annual maintenance in summer. In this run cycle it has accumulated service time of over 7200 hours without major maintenance. The availability of the ion source is above 99.99%, except for one or two sparks per day of the 50 kV high voltage platform, each spark causing 1 second trip of the accelerator. The RF-driven ion source has an external antenna winding around a silicon nitride plasma chamber, which is quite robust in high duty-factor operation. In this paper, we present the structure of the ion source, the improvements over other ion sources, and the issues met in the commissioning.

Deformable registration of medical images based on deep learning has been the research focus this year. Convolutional Neural Network (CNN) and the transformer are the most common backbone and have been shown to enhance registration accuracy. However, CNN lacks the ability to contact long-distance information, and the transformer lacks the ability to capture local information. Whichever subtle feature loss may lead to disastrous consequences in the analysis of clinical medicine. This paper presented a novel registration network named Information Complementation Network (ICN). We aim to improve the registration accuracy by complementing the lost information. Pure transformers can establish long-distance spatial information about the image. Proposed meshing patch embedding can minimize the loss of local information and expand the receptive field to extract long-distance information. The dual-path decoder in ICN is designed to restore information furthest. We experimented on 3D brain MRI data and quantitatively compared several excellent registration models. Compared with conventional methods, the dice coefficient increased by 3%. Compared with the advanced methods, the dice coefficient increased by 1%. The number of foldings was reduced by about 50% without any loss of registration accuracy. Each evaluation metric of the trained models on liver CT images was higher than other methods. By fully complementing the lost or invalid information, ICN achieved higher registration accuracy and smoother deformation field. The innovation and contribution of this paper have the potential to be applied to clinical research or medical image processing.

Super τ-Charm facility (STCF) is a future electron-positron collider operating in the τ-Charm energy region with the aim of studying hadron structure and spectroscopy. The baseline design of the STCF barrel particle identification (PID) detector, which covers momentum up to 2 GeV/c, is provided by a Ring Imaging Cherenkov Counter (RICH). The RICH features an approximately focusing design with liquid perfluorohexane sealed in a quartz container as the radiator and a hybrid combination of CsI-coated THGEMs and Micromegas as the photo-electron detector. A 16×16 cm² prototype with a quartz radiator has been built and tested at DESY and stably operated with an effective gain of 10⁵. In this paper, the design, performance, and reconstruction algorithm of RICH detectors are discussed.

A polychromator is designed based on the transmission volume phase holographic grating spectrometer coupled with avalanched photon diodes through fiber bundle and has been successfully implemented on the Keda Torus eXperiment [Plasma Phys. Control. Fusion 56 (2014) 094009] Thomson scattering system. The polychromator is operated with a 1064 nm laser, and the designed spectral range is from about 1000 nm to 1100 nm. The spectral channels have been optimized with a five-channel design to lower the estimated error of the electron temperature and density within 5% and 3% respectively when the temperature is around 100 eV. With a calibration method about the ratio of the channel average responses using bremsstrahlung radiation, we obtain an electron temperature of 7 eV in a typical experiment with low plasma currents.

Currently there is a large discrepancy between the currents that are used for treatments in proton beam therapy facilities and the ultra low beam currents required for many proton CT imaging systems. Here we provide details of the OPTIma silicon strip based tracking system, which has been designed for performing proton CT imaging in conditions closer to the high proton flux environments of modern spot scanning treatment facilities. Details on the physical design, sensor testing, modelling, and track reconstruction are provided along with Monte-Carlo simulation studies of the expected performance for proton beam currents of up to 50 pA at the nozzle when using a σ= ∼10 mm spot scanning cyclotron system. Using a detailed simulation of the proposed OPTIma system, a discrepancy of less than 1% on the Relative Stopping Power is found for various tissues when embedded within a 150 mm diameter Perspex sphere. It is found that by accepting up to 7 protons per bunch it is possible to operate at cyclotron beam currents up to 5 times higher than would be possible with a single proton based readout, significantly reducing the total beam time required to produce an image, while also reducing the discrepancy between the beam currents required for treatment and those used for proton CT.

Prompt X-ray imaging using a low-energy X-ray camera is a promising method for observing the beam shape from outside the subject. However, such imaging has so far been conducted only on static images with relatively long acquisition times without any energy information. Consequently, we performed list-mode prompt X-ray imaging using a newly developed data acquisition system combined with a pinhole YAP(Ce) camera during irradiation of a water phantom with carbon ions. Prompt X-ray imaging was conducted in list mode with a 1-ms time stamp and 128-channel energy bins during irradiation of a water phantom with 241.5 MeV/n carbon ions. After the imaging, list-mode data were sorted to obtain the time-sequential prompt X-ray images and those with different energies. From the images with different energies, we found the energy spectra were different depending on the areas in the images, and the reduction of the background fraction was possible. From the short time-sequential prompt X-ray images, we could even observe the differences in the images depending on the acquisition times, as well as the spill and ripple shapes of the carbon ion beam.

With the aim of measuring the ²³⁵U(n,f) cross section at the n_TOF facility at CERN over a wide neutron energy range, a detection system consisting of two fission detectors and three detectors for neutron flux determination was realized. The neutron flux detectors are Recoil Proton Telescopes (RPTs), based on scintillators and solid state detectors, conceived to detect recoil protons from the neutron-proton elastic scattering reaction. This system, along with a fission chamber and an array of parallel plate avalanche counters for fission event detection, was installed for the measurement at the n_TOF facility in 2018, at CERN.

An overview of the performances of two RPTs — especially developed for this measurement — and of the parallel plate avalanche counters are described in this article. In particular, the characterization in terms of detection efficiency by Monte Carlo simulations and response to neutron beam, the study of the background, dead time correction and characterization of the samples, are reported. The results of the present investigation show that the performances of these detectors are suitable for accurate measurements of fission reaction cross sections in the range from 10 to 450 MeV.

The European Spallation Source (ESS) in Lund, Sweden will become the world's most powerful thermal neutron source. The Macromolecular Diffractometer (NMX) at the ESS requires three 51.2 × 51.2 cm² detectors with reasonable detection efficiency, sub-mm spatial resolution, a narrow point-spread function (PSF), and good time resolution. This work presents measurements with the improved version of the NMX detector prototype consisting of a Triple-GEM (Gas Electron Multiplier) detector with a natural Gd converter and a low material budget readout. The detector was successfully tested at the neutron reactor of the Budapest Neutron Centre (BNC) and the D16 instrument at the Institut Laue-Langevin (ILL) in Grenoble. The measurements with Cadmium and Gadolinium masks in Budapest demonstrate that the point-spread function of the detector lacks long tails that could impede the measurement of diffraction spot intensities. On the D16 instrument at ILL, diffraction spots from Triose phosphate isomerase w/ 2-phosphoglycolate (PGA) inhibitor were measured both in the MILAND Helium-3 detector and the Gd-GEM. The comparison between the two detectors shows a similar point-spread function in both detectors, and the expected efficiency ratio compared to the Helium-3 detector. Both measurements together thus give good indications that the Gd-GEM detector fits the requirements for the NMX instrument at ESS.

The aim of the presented article is to share experience gained throughout the course of two projects focused on precise grinding of a free-form glass optical element with the objective of achieving a surface shape error of less than approximately 10 μm PV before the subsequent polishing phases. Compared to spheres or aspheres machining, it is considerably more demanding, mainly due to the impossibility of using rotationally symmetric shape corrections. The developed and tested process combines a mechanical engineering approach based on the use of the current Computer Aided Design and Computer Aided Manufacturing software with their respective strengths and weaknesses and an optical engineering approach, for which the employment of CNC machines featuring precise control but low flexibility is typical. Therefore, attention is paid mainly to the description of particular process steps like CAD construction and CNC grinding step programming with regard to the necessary software and data handling, as well as the required parametrisation of the used machine equipment.

Recent progress in the field of micron-scale spatial resolution direct conversion X-ray detectors for high-energy synchrotron light sources serve applications ranging from nondestructive and noninvasive microscopy techniques which provide insight into the structure and morphology of crystals, to medical diagnostic measurement devices. Amorphous selenium (a-Se) as a wide-bandgap thermally evaporated photoconductor exhibits ultra-low thermal generation rates for dark carriers and has been extensively used in X-ray medical imaging. Being an amorphous material, it can further be deposited over large areas at room temperatures and at substantially lower costs as compared to crystalline semiconductors. To address the demands for a high-energy and high spatial resolution X-ray detector for synchrotron light source applications, we have thermally evaporated a-Se on a Mixed-Mode Pixel Array Detector (MM-PAD) Application Specific Integrated Circuit (ASIC). The ASIC format consists of 128 × 128 square pixels each 150 μm on a side. A 200 μm a-Se layer was directly deposited on the ASIC followed by a metal top electrode. The completed detector assembly was tested with 45 kV Ag and 23 kV Cu X-ray tube sources. The detector fabrication, performances, Modulation Transfer Function (MTF) measurements, and simulations are reported.

Laser-driven magnetic reconnection (LDMR) is an important research topic in the field of high-energy-density physics, such as laboratory astrophysics. In this study, the narrow bandwidth spontaneous light imaging (SLI) technique at the extreme ultraviolet (EUV) band is introduced to detect magnetic reconnection and the jets produced by LDMR. The EUV-based SLI technique will provide reference values for the verification of the results obtained with traditional methods.

To reduce Touschek scattering in the beam and extend the lifetime of the beam in the Shenzhen Innovation Light-source Facility (a fourth-generation light source), a 1500 MHz passive third harmonic system will be used. The present work is devoted to the RF design and frequency sensitivity analysis of the 1500 MHz passive third harmonic superconducting cavity, optimizing the RF parameters of the cavity, and giving a frequency scheme for the cavity in fabrication. The reliability of the cavity during operation is taken as the main goal for the optimization of the geometrical parameters, and its structural and RF parameters are obtained with E_peak/E_acc of 2.17, B_peak/E_acc of 5.12 mT/(MV/m) and G · R/Q of 25052 at 2 K. A pair of fluted beam pipes are used to propagate the higher order modes (HOMs) of the harmonic cavity, allowing a smooth transition of the first dipole mode to the absorber located at room temperature area. For the frequency sensitivity analysis, the frequency variations of the cavity in fabrication are obtained by multi-physics coupling simulation in the paper, which gives the target frequency of the cavity between welding and preloading. After electron beam welding (EBW), the resonant frequency of the cavity should be maintained at 1500.096 MHz, and the pre-tuning target frequency is 1497.456 MHz. The slow tuning range is ±400 kHz, the fast-tuning range is 600 Hz, and the maximum allowable tuning force is 15 kN.

We present a study of factors affecting the energy spread of ion beams extracted from a Charge Breeder Electron Cyclotron Resonance Ion Source (CB-ECRIS). The comprehensive simulations, supported by experiments with a Retarding Field Analyser (RFA), reveal that the longitudinal and transverse energy spread of the extracted beams are strongly affected by the electrostatic focusing effects, namely the extraction geometry and plasma beam boundary, to the extent that the electrostatic effects dominate over the magnetic field induced rotation of the beam or the effect of plasma potential and ion temperature. The dominance of the electrostatic focusing effect over the magnetic field induced rotation complicates parametric studies of the transverse emittance as a function of the magnetic field strength, and comparison of emittance values obtained with different ion sources having different extraction designs. Our results demonstrate that the full ion beam energy spread, relevant for the downstream accelerator, can be measured with the RFA only when all ions are collected. On the contrary, studying the effect of plasma properties (plasma potential and ion temperature) on the longitudinal energy spread requires heavy collimation of the beam accepting only ions near the symmetry axis of the beam for which the electrostatic and magnetic effects are suppressed. As the extraction system of the CB-ECRIS is similar to a conventional ECRIS, the conclusions of the study can be generalised to apply for all high charge state ECR ion sources. Finally, we present the results of systematic plasma potential measurements of the Phoenix-type CB-ECRIS at LPSC, varying the source potential, the microwave power and the axial magnetic field srength. It was observed that the plasma potential increases with the extraction magnetic field and the microwave power.

We have designed and implemented an experiment to measure the angular distributions and the energy spectra of the transition radiation X-rays emitted by fast electrons and positrons crossing different radiators. Our experiment was selected among the proposals of the 2021 Beamline for Schools contest, a competition for high-school students organized every year by CERN, and was performed at the DESY II Test Beam facility area TB21, using a high-purity beam of electrons or positrons with momenta in the range from 1 to 6 GeV/c. The measurements were performed using a 100 μm thick silicon pixel detector, with a pitch of 55 μm. Our results are consistent with the expectations from the theoretical models describing the production of transition radiation in multilayer regular radiators.

We have developed an MCP detector with reconfigurable read-out which is capable of recording the position and time information for single particle counting and alternatively of operating at high particle flux with optical read-out. This is achieved by a Resistive Screen with embedded Phosphor (RSP) anode. On demand, signal pickup electrodes such as a delay-line array can be attached or removed without interfering with vacuum, allowing easy switching between the different operation modes. We show tests of a prototype.

We present technical design and characteristics of the magnetic shield developed for 20" PMTs of the low-background OSIRIS facility. A ribbon of amorphous alloy with extreme magnetic permeability was used in its design, providing excellent efficiency in screening the Earth's magnetic field with a relatively small amount of material. The mass of materials is crucial to construction of low-background facilities because of radioactive backgrounds. Using amorphous materials is cost-efficient compared to other methods for screening the Earth's magnetic field.

The D-Egg, an acronym for "Dual optical sensors in an Ellipsoid Glass for Gen2," is one of the optical modules designed for future extensions of the IceCube experiment at the South Pole. The D-Egg has an elongated-sphere shape to maximize the photon-sensitive effective area while maintaining a narrow diameter to reduce the cost and the time needed for drilling of the deployment holes in the glacial ice for the optical modules at depths up to 2700 m.

The D-Egg design is utilized for the IceCube Upgrade, the next stage of the IceCube project also known as IceCube-Gen2 Phase 1, where nearly half of the optical sensors to be deployed are D-Eggs. With two 8-inch high-quantum efficiency photomultiplier tubes (PMTs) per module, D-Eggs offer an increased effective area while retaining the successful design of the IceCube digital optical module (DOM). The convolution of the wavelength-dependent effective area and the Cherenkov emission spectrum provides an effective photodetection sensitivity that is 2.8 times larger than that of IceCube DOMs. The signal of each of the two PMTs is digitized using ultra-low-power 14-bit analog-to-digital converters with a sampling frequency of 240 MSPS, enabling a flexible event triggering, as well as seamless and lossless event recording of single-photon signals to multi-photons exceeding 200 photoelectrons within 10 ns. Mass production of D-Eggs has been completed, with 277 out of the 310 D-Eggs produced to be used in the IceCube Upgrade. In this paper, we report the design of the D-Eggs, as well as the sensitivity and the single to multi-photon detection performance of mass-produced D-Eggs measured in a laboratory using the built-in data acquisition system in each D-Egg optical sensor module.

Antiproton annihilations on matter nuclei are usually detected by tracking the charged pions emitted in the process. A detector made of plastic scintillating bars have been built and used in the ASACUSA experiment for the last 10 years. Ageing, movements and transports caused stress on the internal mechanical structure and impacted mostly on the optical readout system which was eventually upgraded: the so far used multi-anode photo-multiplier tubes (PMTs) have been replaced by silicon photomultipliers (SiPM) and the front-end electronics had to be adapted to cope with the new signal formation. This work describes the design and operations of the upgrade, as well as the validation tests with cosmic rays.

Accurate conversion of neutron time-of-flight (TOF) to wavelength is of fundamental importance to neutron scattering measurements in order to ensure the accuracy of the instruments and the experimental results. Equally important in these measurements is the determination of uncertainties, and with the appropriate precision. Especially in cases where instruments are highly configurable, the determination of the absolute wavelength after any change must always be performed (e.g. change of detector position). Inspired by the manner with which neutron spectrometers determine the absolute wavelength, we evaluate for the first time, in the author's knowledge, a commonly used method for converting TOF to neutron wavelength by measuring the neutron flight path length from the source of neutrons to a monitor and we proceed to analytically calculate the uncertainty contributions that limit the precision of the conversion. The method was evaluated at the V20 test beamline at the Helmholtz Zentrum Berlin (HZB), emulating the ESS source with a long pulse of 2.86 ms length and 14 Hz repetition rate, by using a mini-chopper operated at 140 Hz and two portable beam monitors (BMs), as well as accompanied data acquisition infrastructure. The mini-chopper created well-defined neutron pulses and the BM was placed at two positions, enabling the average wavelength of each of the pulses created to be determined. The used experimental setup resulted in absolute wavelength determination at the monitor positions with a δλ_mean / λ_mean of ∼1.8% for λ > 4 Å. With the use of a thinner monitor, a δλ_mean / λ_mean of ∼1% can be reached and with a modest increase of the distance between the reference monitor positions a δλ_mean / λ_mean of below 0.5% can be achieved. Further improvements are possible by using smaller chopper disc openings and a higher rotational speed chopper. The method requires only two neutron measurements and doesn't necessitate the use of crystals or complex fitting with sigmoid functions and multiple free variables, and could constitute a suitable addition to imaging, diffraction, reflectometers and small angle neutron scattering instruments, at spallation sources, that do not normally utilise fast choppers.

Low-energy background through Compton scattering from the ambient γ rays can be contaminated in direct dark matter search experiments. In this paper, we report comparable measurements on low-energy spectra via Compton scattering from severalγ-ray sources with a p-type point-contact germanium detector. The spectra between 500 eV and 18 keV have been measured and analyzed. Moreover, the features of the electron binding effect, particularly at the edges of the K- and L-shells in the germanium atom, were observed with different gamma sources and were consistent with the models in the Geant4 simulation. An empirical background model is proposed that provides insights into understanding the low-energy background in germanium for direct dark matter experiments.

The complex non-linear processes in multi-dimensional parameter spaces, that are typical for an accelerator, are a natural application for machine learning algorithms. This paper reports on the use of Bayesian optimization for the optimization of the Injection Beam Line (IBL) of the Cooler Synchrotron storage ring COSY at the Forschungszentrum Jülich, Germany. Bayesian optimization is a machine learning method that optimizes a continuous objective function using limited observations. The IBL is composed of 15 quadrupoles and 28 steerers. The goal is to increase the beam intensity inside the storage ring. The results showed the effectiveness of the Bayesian optimization in achieving better/faster results compared to manual optimization.

We studied the light yield of a pure polystyrene slide coated with wavelength-shifter molecules, coupled to a photomultiplier, using β^- particles from a ⁹⁰Sr source, as a possible easy-to-build, low-cost plastic scintillator detector. Comparison measurements were performed with an uncoated polystyrene slide as well as with uncoated and coated PMMA slides, the latter which can only produce Cherenkov light when being traversed by charged particles. The results with the single (double) coated polystyrene slides show about 4.9 (6.3) times higher detected photon yield compared to the uncoated slide. For comparison, the light yield of a polystyrene-based extruded plastic scintillator material doped with PTP and POPOP was measured as well. The absolute detected light yield motivates future studies for developing easy-to-build, low-cost polystyrene-based plastic scintillator detectors.

Inductively-coupled plasma discharges are well-suited as plasma sources for experiments in fundamental high-energy density science, which require large volume and stable plasmas. For example, experiments studying particle beam-plasma instabilities and the emergence of coherent macroscopic structures — which are key for modelling emission from collisionless shocks present in many astrophysical phenomena. A meter-length, table-top, inductive radio-frequency discharge has been constructed for use in a high-energy density science experiment at CERN which will study plasma instabilities of a relativistic electron-positron beam. In this case, a large volume is necessary for the beam to remain inside the plasma as it diverges to centimeter-scale diameters during the tens-of-centimeters of propagation needed for instabilities to develop. Langmuir probe measurements of the plasma parameters show that plasma can be stably sustained in the discharge with electron densities exceeding 10¹¹ cm^-3. The discharge has been assembled using commercially-available components, making it an accessible option for commissioning at a University laboratory.

In this article, a bandpass filter (BPF) is proposed by etching stepped impedance complementary split ring resonators (SICSRRs) pairs in parallel with series gaps on the top side of a coplanar waveguide (CPW). The Nicolson-Ross-Weir (NRW) method is used to analyze the left-handed (LH) behavior of the filter. The effects of the resonators parameters on the left-handed BPF are studied. The parameters and number of the resonators are adjusted properly to obtain the desired filter characteristics. Split ring resonators (SRRs) are magnetically coupled to the BPF to realize a novel left-handed dual-band bandpass filter. Besides, The dual-band filter is described by means of the lumped-element equivalent circuit model. Also, the quasi-static analysis is used to obtain the equations for the resonant frequencies of the resonators. The efficient electrical size of the dual-band filter is 0.51λ_g × 0.42λ_g where λ_g  represents the guided wavelength at the first passband center frequency. The prototype of the compact dual-band BPF is fabricated and measured. The measured results reveal low insertion loss and high return loss at the passbands along with wide upper stopband attenuation. The measured result is in a good agreement with the corresponding simulation result.

Radon and its daughters are one of the most important background sources for low-background liquid scintillator (LS) detectors. The study of the diffusion behavior of radon in the LS contributes to the analysis of the related background caused by radon. Methodologies and devices for measuring radon's diffusion coefficient and solubility in materials are developed and described. The radon diffusion coefficient in the LS was measured for the first time and the solubility coefficient was also obtained. In addition, the radon diffusion coefficient in the polyolefine film which is consistent with data in the literature was measured to verify the reliability of the diffusion device.

The Fermilab Mu2e experiment aims to observe charged lepton flavor violation through the direct conversion of a muon to an electron. This can be accomplished with the considerable challenge of manipulating and transporting large numbers of protons confined to a narrow phase space region without significant particle losses or deterioration of beam quality before reaching the production target. In this paper we report the first results from the commissioning the beamline upstream the Mu2e production target. We first discuss the evolution of the beam distribution in x-y  plane after collecting a series of beam profiles along the line. Then, we discuss the beam evolution in phase-space by measuring the beam's Twiss parameters using two independent techniques. Finally, with the aid of numerical simulations we compare our measured data with design parameters and discuss similarities and differences observed.

The Back-n white neutron source at the China Spallation Neutron Source (CSNS) provides neutrons in the continuous energy region from 0.5 eV to 200 MeV. A spectrometer named Light charged Particle Detector Array (LPDA) is designed for the study of (n, lcp) reactions at Back-n. The main detector of the LPDA spectrometer, a 16-unit ΔE-ΔE-E telescope array, is composed of two arrays of 8-unit ΔE-ΔE-E  telescope. Each telescope unit consists of a Low-Pressure Multi-Wire Proportional Chamber (LPMWPC), a Si-PIN detector, and a CsI(Tl) scintillator detector. In 2021, a neutron-proton (n-p) scattering reaction cross-section measurement experiment was accomplished as the first experiment of the telescope array. Protons can be clearly identified in the ΔE-E spectrum (LPMWPC + Si-PIN) and the ΔE-E spectrum (Si-PIN + CsI(Tl)). Cross sections of the n-p scattering reaction in the neutron energy range of several MeV are extracted. The ΔE-E method also provides new measurement opportunities for many-body neutron induced light charged-particle emission reactions.

The excellent wall condition is essential for fusion devices to generate reproducible high-parameter plasma. Wall conditioning techniques should be validated before applying on large fusion devices to reduce potential risk. Helimak, a toroidal steady state magnetic confinement device, was reassembled and upgraded to a technical validation platform for wall conditioning. A new control system has been developed to achieve the upgrade of Helimak. The control system is based on a distributed control architecture, which provides not only efficient development but also flexible control mechanisms. For each auxiliary subsystem, a corresponding local control module is developed to drive and control a variety of equipment. The control network ensures real-time transmitting of the parameters and data. A dedicated trigger network and timing control module can improve synchronization and real-time performance. Data acquisition system based on mature commercial busses provides sufficient data acquisition capabilities for diagnostic tools. The data management system uses MDSplus to provide convenient data access. An independent interlock and safety system is designed for comprehensive and reliable personal protection. After engineering commissioning, the Helimak has realized wall conditioning by electron cyclotron resonance heating (ECRH) plasma at different resonance positions. The flexibility of control systems allows the installation of more wall conditioning tools in the future that will provide the ability to validate combined wall conditioning techniques. Helimak will become a low-cost, reliable technology verification platform, which will help to achieve advanced scenarios in tokamak and stellarator.

The radiation detector output is often shaped into Gaussian or quasi-Gaussian shape to improve the measurement performance. An adaptive digital Step-Gaussian filter is presented for quasi-Gaussian pulse shaping in this paper. It can be applied for both exponential decay input and step input. The transfer function of the filter is established. The amplitude-frequency features of the new filter are compared with the PZC-(RC)ⁿ filter and the CR-(RC)ⁿ filter. The results indicate that the new filter has the same amplitude-frequency features as the PZC-(RC)ⁿ filter and it possesses more effective filter performance than the CR-(RC)ⁿ filter. An X-ray fluorescence measurement system based on a FAST-SDD detector is set up for experiments. The proposed filter is verified by the measured pulses that are generated from a manganese sample. The shape of the filter output shows that the Step-Gaussian filter can eliminate the undershoot that exists in the CR-(RC)ⁿ filter output. The amplitude spectrums with different shaping times are created to study the shape of the characteristic peak. The results show that the Step-Gaussian filter can cancel the low-energy peak tailing of the 5.89 keV peak. The peak shape parameter, FWTM/FWHM ratio, is also introduced to evaluate the performance of peak shape improvement. The 5.89 keV peaks of the spectrums that are generated by using Step-Gaussian filter are closer to Gaussian distribution than that of the CR-(RC)ⁿ  filter.

The Large Hadron Collider (LHC) at CERN will undergo major upgrades to increase the instantaneous luminosity up to 5–7.5×10³⁴ cm^-2s^-1. This High Luminosity upgrade of the LHC (HL-LHC) will deliver a total of 3000–4000 fb^-1 of proton-proton collisions at a center-of-mass energy of 13–14 TeV. To cope with these challenging environmental conditions, the strip tracker of the CMS experiment will be upgraded using modules with two closely-spaced silicon sensors to provide information to include tracking in the Level-1 trigger selection. This paper describes the performance, in a test beam experiment, of the first prototype module based on the final version of the CMS Binary Chip front-end ASIC before and after the module was irradiated with neutrons. Results demonstrate that the prototype module satisfies the requirements, providing efficient tracking information, after being irradiated with a total fluence comparable to the one expected through the lifetime of the experiment.

This article presents a new method for estimating the electron temperature of the Proto-sphera's screw pinch. The temperature radial profile is obtained by a self-consistent modeling of a 1D MHD equilibrium along with a 0D power balance of the plasma column, given measurements and estimates of the axial pinch plasma current, of the plasma rotational frequency and, at the equatorial plane, of the electron density radial profile, of the edge poloidal magnetic field, of the edge electron temperature and of the neutrals pressure in the vacuum vessel. The plasma is considered in equilibrium with its neutral phase and in constant rotation. A MATLAB code has been developed with the aim of estimating the MHD radial equilibrium profiles, the thermodynamic plasma state and the neutrals profile. The numerical estimates are compared with available experimental data showing a good agreement.

Compact accelerator machines are capable of producing accelerating gradients in the GV/m scale, which is significantly higher than the MV/m scale of conventional machines. As accelerators are widely used in many fields, such as industrial, research institutes, and medical applications, the development of these machines will undoubtedly have a profound impact on people's daily lives. SPARC_LAB, a test facility at INFN-LNF (Laboratori Nazionali di Frascati), is focused on enhancing particle accelerator research infrastructure using innovative plasma acceleration concepts. Within SPARC_LAB, we utilize plasma-filled capillaries with lengths of up to tens of centimeters. However, the plasma formation process is critical to ensure proper oversight of the plasma properties, which subsequently affects the dynamics of the electron bunch to be accelerated. One of the most critical points that significantly affects the properties of the electron beam passing through the plasma source is the shot-by-shot stability of the plasma density along the longitudinal dimension of the plasma-discharge capillary. Therefore, this paper aims to investigate the shot-by-shot stability of the plasma density during discharge, contributing to further advancements in the field of plasma acceleration.

The MOPSv2 chip is an Application Specific Integrated Circuit (ASIC) to provide the temperature and the voltage monitoring data of individual front-end detector modules to the DCS of the ATLAS ITk Pixel detector. The chip implements CANopen in a hardwired logic, provides the possibility of remote reset without a power cycle and automated on-chip frequency trimming using CAN messages. The chip has proven to be radiation hard during testing up to an ionizing dose of 500 Mrad, immune to Single Event Upsets (SEUs) and works reliably under irradiation at high operating temperatures of up to 40 °C. In this paper, the functionality and performance of the second version of the chip will be discussed, and also results from the irradiation campaigns will be presented.

Measurements of internal magnetic fields are of primary importance in laboratory plasma physics; the most common diagnostic method is Faraday rotation measurement by means of polarimetry. Faraday rotation measurements are integrated along a line of sight: the overall rotation is proportional to the plasma density, magnetic field and probing wavelength, as well as to the integration segment length and hence to the plasma dimensions. As a results, measurements of small magnetic fields in small, low density plasmas becomes non-trivial; on the other hand, this is typically the situation of small, self organized laboratory experiments. Being the probing wavelength practically limited to the THz region by diffraction phenomena, the use of a multipass scheme is actually the only way to improve the diagnostic sensitivity. This work discuss an application study of a multipass cavity to the PROTO-SPHERA experiment, but the results can be easily generalized to others of similar characteristics. In particular, different layouts are analyzed (straight, folded, annular cavity) discussing the overall stability region, the impact of changes in plasma refraction and the overall performances in terms of photon lifetime. The performance analysis features a discussion on continuous vs pulsed regime as well as on some basic detection schemes (direct, closed loop feedback).

We present a design of the scalable processor capable of providing an artificial neural network (ANN) functionality and in-house developed tools for automatic conversion of an ANN model designed with the TensorFlow library into an HDL code. The hardware is described in SystemVerilog and the synthesized module of the processor can perform calculations of a neural network with the speed exceeding 100 MHz. Our in-house designed software tool for ANN conversion supports translation of an arbitrary multilayer perceptron neural network into a state machine module, which performs necessary calculations. It is also dynamically reconfigurable so that the ANN operating on the hardware can be changed after it is deployed as an ASIC. The project aims the in-pixel implementation towards an X-ray photon energy estimation. The energy estimation shall be delivered with accuracy that exceeds the accuracy of an ADC converter that feeds the ANN with data.

Lithium fluoride (LiF) crystals and thin films have been successfully investigated as X-ray imaging detectors based on optical reading of visible photoluminescence emitted by stable radiation-induced F₂ and F⁺₃ colour centres. In this work, the visible photoluminescence response of optically-transparent LiF film detectors of three different thicknesses, grown by thermal evaporation on Si(100) substrates and irradiated with monochromatic 7 keV X-rays at several doses in the range between 13 and 4.5 × 10³ Gy, was carefully investigated by fluorescence optical microscopy. For all the film thicknesses, the photoluminescence response linearly depends on the irradiation dose in the investigated dose range. The lowest detected dose, delivered to the thinnest LiF film, only 0.5 μm thick, is estimated 13 Gy. Edge-enhancement imaging experiments, conducted by irradiating LiF film detectors at the same energy placing an Au mesh in front of them at a distance of 15 mm, allowed estimating a spatial resolution of (0.38 ± 0.05) μm, which is comparable to the microscope one. This very high spatial resolution in LiF film radiation detectors based on colour centres photoluminescence is combined with the availability of a wide field of view on large areas.

The new electronics of the ATLAS Tile Calorimeter for the HL-LHC interfaces the on-detector and off-detector electronics by means of a Daughterboard. The Daughterboard is positioned on-detector featuring commercial SFPs+, CERN GBTx ASICs, ProASIC FPGAs and Kintex Ultrascale FPGAs. The design minimizes single points of failure and mitigates radiation damage by means of a double redundant scheme, Triple Mode Redundancy, Xilinx Soft Error Mitigation IP, CRC/FEC for link data transfer, and SEL protection circuitry. We present an updated summary of the TID, NIEL and SEE qualification tests, and performance studies of the Daughterboard revision 6 design.

LiDAR is an acronym of "Light Detection and Ranging", which is to measure the distance to an object ("Ranging") by detecting the light being reflected ("Light Detection"). The "hands-on" lab is made of two sections: (1) overviewing the technology, the application, and the key devices of LiDAR, and (2) a laboratory where we operate a LiDAR setup, do calibration, and look into signals in the electronics. In the section (1), we learn the "basics" of the LiDAR. In the section (2), we learn "real stuff" by using a LiDAR setup. We use a simple desktop LiDAR setup developed by Hamamatsu photonics K.K. (HPK), adapted for the hands-on lab in collaboration with the author. The LiDAR setup, which is using "cutting-edge" solid-state devices, is a direct time-of-flight LiDAR equipped with a 905 nm laser diode and a 16-ch MPPC photon counting image sensor. The light emitter is a pulsed solid-state laser (PLD) of 905 nm infra-red light. The light receiver (a photon counting image sensor (PCI)) is a linear-array of 16 channel MPPC (a solid-state photomultiplier) with a readout ASIC. The setup is also equipped with a visible-light camera, with which we correlate the visual image with the feature of the LiDAR setup. In the LiDAR laboratory, we do "aiming" (i.e., calibrate) by detecting the infra-red laser light, and correlating visual imaging and LiDAR "ranging". We get insight into the LiDAR setup by monitoring time-of-flight (TOF) and energy (pulse height with time-over-threshold technology (TOT)) signals in the electronics with an oscilloscope. Through the process, we learn the real stuff of LiDAR and the issues associated.

A line driver with configurable pre-emphasis is implemented in a 65 nm CMOS process. The driver utilizes a three-tap feed-forward equalization architecture. The relative delays between the taps are selectable in increments of 1/16th of the unit interval via an 8-stage delay-locked loop and digital interpolator. It is also possible to control the output amplitude and source impedance for each tap via a programmable array of eight source-series terminated drivers. The entire design consumes 9 mW from a 1.2 V supply at 1 Gb/s.

Non-invasive range measurement of particle beams is important to prevent deviation of the irradiated area in particle therapy. In this study, we made an experiment of imaging carbon-ion beams by setting the projection ranges into an acrylic target from 4.29 cm to 7.65 cm by a pitch of 0.21 cm. Secondary electron bremsstrahlung (SEB) generated on the beam trajectories were detected for the imaging by use of a pinhole camera system consisting of a pinhole collimator and a position-sensitive cadmium-telluride semiconductor detector (CdTe imager). Beam images were acquired, and their profiles along the longitudinal axis were numerically analyzed, to obtain a suitable parameter that was strongly correlated with the set range. Then we could propose a scheme to measure the particle beam range in the target during irradiation by use of the CdTe imager. As a result, the range shift can be measured in the case of the acrylic target with an accuracy of 0.1 cm.

The LUX-ZEPLIN (LZ) detector is a dual-phase liquid xenon time projection chamber (TPC) installed at the Sanford Underground Research Facility (Lead, South Dakota) at a depth of 1478 meters. Although the main objective of LZ is the direct detection of dark matter, its low background environment allows for the search of other rare processes, such as the neutrinoless double beta decay of xenon isotopes ¹³⁴Xe and ¹³⁶Xe with the respective Q-values of 826 keV and 2458 keV. The sensitivity of the detector to these decays is directly determined by the energy resolution, which, in turn, is degraded by non-uniformities in detector response. In this work, we present a novel method to correct, in the data, the non-uniformity of the light collected by an array of photosensors in a scintillation detector. This method is based on the knowledge of the light response functions of individual photosensors. With these techniques, we report, at a very early phase of the detector operations, a state-of-the-art energy resolution (σ/μ) of (0.67 ± 0.01)% at 2614 keV for the fiducial volume of 5.6 tonnes of liquid xenon.

For the High-Luminosity upgrade of the LHC, the current ATLAS inner detector will be replaced with a new silicon charged-particle tracker, the ITk, which consists of the ITk Pixel and the ITk Strip subdetector. The high voltage multiplexing (HV-Mux) GaNFETs are radiation-tolerant transistors that permit switching off high voltage to malfunctioning sensors on the ITk Strip modules. To ensure the reliability of the GaNFETs in the high radiation environment expected at the HL-LHC, a sample of the production batch was exposed to gamma radiation. The GaNFETs were characterized pre-irradiation and post-irradiation, and monitored during irradiation.

Recent advancements in high-dose-rate brachytherapy have led to remarkable clinical outcomes. However, these new developments can cause unknown uncertainties with respect to actual dose delivery, which are yet to be clarified. Therefore, an accurate dose verification system is required. Currently, procedures for image-guided adaptive brachytherapy are constrained by the following limitations: (1) patient transportation between the treatment room and CT/MR (computerized tomography/magnetic resonance) imaging room can displace the application position, (2) the physiological and anatomical changes in the patient's body cannot be observed during the treatment schedule involving 3–10 fraction, and (3) the movement of the radioactive source inside the body is impossible to track. This study proposes a concept of an integrated online imaging system, which is based on integrated CT and single-photon emission computed tomography (SPECT), namely, the C-arm CT/SPECT system—a combination of a C-arm fluoroscopic x-ray imaging system and an attachable parallel-hole collimator over the imaging detector. The Geant4 software is used to simulate the application of the C-arm CT/SPECT system for ¹⁹²Ir-based brachytherapy in a pelvis-like phantom. To improve the image quality of C-arm CT/SPECT acquired with limited-angle information, we utilized an adaptive-steepest-descent-projection-onto-convex-sets framework that incorporates additional prior information for the proposed system. Furthermore, we confirmed that SPECT images can be obtained using a parallel-hole collimator and estimated the dose distribution in the medium and CT/SPECT fusion imaging during treatment. This strategy is expected to be effectively implemented in online image-guided adaptive brachytherapy and patient-dose verification.

The Deep Underground Neutrino Experiment (DUNE) will be using a liquid argon time projection chamber (LAr TPC) with optically separated modules in the Near Detector (ND) complex. A prototype experiment, DUNE ND-LAr 2 × 2, is composed of four test modules. They detect ionization charge through a pixel-based readout and scintillation light through fibers in light collection modules and light traps called ArCLights. The light detection performance for two modules of DUNE ND-LAr 2 × 2 that took cosmic ray data at the University of Bern is shown. We present further the role of the 2 × 2 prototype in DUNE and how it is used to demonstrate the reconstruction capabilities of its light detectors in terms of energy thresholds and timing resolution.

The MALTA CMOS monolithic silicon pixel sensors has been developed in the Tower 180 nm CMOS imaging process. It includes an asynchronous readout scheme and complies with the ATLAS inner tracker requirements for the HL-LHC. Several 4-chip MALTA modules have been built using Al wedge wire bonding to demonstrate the direct transfer of data from chip-to-chip and to read out the data of the entire module via one chip only. Novel technologies such as Anisotropic Conductive Films (ACF) and nanowires have been investigated to build a compact module. A lightweight flex with 17 μm trace spacing has been designed, allowing compact packaging with a direct attachment of the chip connection pads to the flex using these interconnection technologies. This contribution shows the current state of our work towards a flexible, low material, dense and reliable packaging and modularization of pixel detectors.

Being installed as close as 5.5 mm to the beam axis, the Micro Vertex Detector (mvd) of the cbm experiment will be exposed to a sizable flow of heavy beam ions and nuclear fragments. The cmos Monolithic Active Pixel Sensor for the mvd, mimosis, must resist the related heavy ion impacts without permanent damage or frequent interrupt of operation as caused by single event effects (see). We motivate the requirements on the sensor and introduce our concept for protecting the device against sees. Moreover, we report the results of a related test campaign carried out with the first full size sensor prototype, mimosis-1, and different heavy ion beams at gsi.

Our group has been developing DPECT (Double Photon Emission CT) to enhance nuclear medicine diagnostics using cascade nuclides that emit multiple gamma rays simultaneously. It is possible to detect the local environment around the nuclide by examining the angular correlation of the emitted cascade gamma-rays. In this study, with the goal of developing a new imaging method combining ultrasound and nuclear medicine, we investigated the effect of ultrasound on cascade gamma-ray emission and found that the angular correlation could be changed by a micro-electric field around ¹¹¹In in an aqueous solution caused by ultrasound irradiation. Using 8 × 8 array of GAGG scintillators as a detector and Hamamatsu Photonics 8 × 8 MPPCs as a photomultiplier, eight detectors were used and arranged in a ring shape to surround the point source ¹¹¹In from 360° direction. For the readout system, using a dynamic ToT board, read out its channel information, energy information as ToT signal, and detection time information simultaneously and independently concerning gamma-ray detection. We measured the angular correlation change with four types of ultrasound intensities of 0.05 V, 0.10 V, 0.15 V, and 0.20 V input voltage, and found that the gamma-ray emission angle distribution decreased by about up to 5% around the 90° direction and increased by about up to 5% around 0° and 180° for an ultrasound with an input voltage of 0.15 V or higher.

We perform a detailed simulation of a pixelated CdTe detector using the GEANT4 toolkit completed with a custom code emulating the detector's electronic response. We demonstrate that a measured tungsten X-ray spectrum can be majorly restored back to the original incident spectrum using the developed model, without requiring the dedicated hardware charge sharing correction.

Bismuth germanium oxide (Bi₄Ge₃O₁₂, BGO) scintillation crystals are widely used as detectors in the fields of particle physics and astrophysics due to their high density, and thus higher efficiency for gamma-ray detection. Owing to their good chemical stability, they can be used in any environment. For rare-event searches, such as dark matter and coherent elastic neutrino-nucleus scattering, BGO crystals are essential to comprehend the response of nuclear recoil. In this study, we have analyzed the events of neutron elastic scattering with oxygen in BGO crystals. Then, we have measured the quenching factor for oxygen recoil energy in the BGO crystal as a function of recoil energy by using a monoenergetic neutron source.

We present the cost-effective production of superconducting radio frequency (SRF) cavities made of medium grain (MG) niobium (Nb) discs directly sliced from forged and annealed billet. This production method provides clean surface conditions and reliable mechanical characteristics with sub-millimeter average grain size resulting in stable SRF cavity production. We propose to apply this material to particle accelerator in the science and industrial applications. The science applications require high field gradients(≥ 30 MV/m) particularly in pulsed mode. The industrial applications require high Q₀ values with moderate gradients (∼ 20 MV/m) in CW mode operation. This paper describes the MG Nb disc production recently demonstrated and discusses future prospects for application in advanced particle accelerators in the science and industrial applications.

A beam position monitor (BPM) is built and tested to monitor the stability of high intensity proton beams accelerated by a 70 MeV cyclotron for ISOL operation in the aspects of beam position and current. The prototype BPM has four pick-up electrodes with a length of 19 cm and uses Libera Spark™ to process signals. It was firstly tested using a moving wire method to calibrate beam positions and further tested when installed in the beam line together with a beam profile monitor during beam commissioning of the cyclotron. The prototype system produced well-defined signals for two transverse directions with a resolution of 0.1 mm and for beam intensity up to 600 μA. A beam-stop signal can be issued by the readout program for the Spark when beam instabilities evaluated by the program reach certain limits set for each operation. The non-destructive BPM monitoring of high-current beams will be integrated into the safety PLC after a series of ISOL operation are carried out.

Gold wire is commonly used for quality assurance (QA) of the neutron beam in a boron neutron capture therapy (BNCT) system. It is set in water and irradiated with the neutron beam, and then 412-keV gamma photons from the activated gold wire are measured by a semiconductor detector. Since this procedure takes time and labor, a more efficient method is desired. To reduce the time and labor to measure the radioactivity of an activated gold wire, we carried out imaging of 412-keV gamma photons from the activated gold wire using a developed high-energy gamma camera. After the gold wire was set in the depth direction in a water-filled phantom and irradiated with neutron beams using the BNCT system, gamma photon imaging was conducted with the developed high-energy gamma camera. On the measured image, a depth profile was set to obtain the neutron distribution, and this was compared with the profile sequentially measured with a semiconductor detector. An image of the 412-keV gamma photons was obtained with an imaging time of 1.5 hours. The estimated depth profile of the neutron beam from the gamma camera image closely matched that measured with a semiconductor detector. Imaging of the gamma photons emitted from the activated gold wire was possible, and it offers an efficient method to measure the thermal neutron distribution of the BNCT system. This method has the potential to reduce the time and labor for QA of a BNCT system.

Muon veto is an important technique of many low background experiments. With the push in improving the sensitivity and statistics, the size of the detector for particle experiments has also been increasing. Therefore, there is a greater demand on the size of the muon veto system to efficiently identify muon events passing through the detector, minimizing the associated dead time of the target detector, and simultaneously fitting in the space requirements. In this paper, two designs of muon veto detectors composed of 200 cm×20 cm×2 cm plastic scintillator strip and a wavelength shifting(WLS) fiber coupled with SiPM, are tested. We use cosmic muons to examine the plastic scintillator along the length by scintillator cubes as probes and therefore measuring photoelectron numbers as a function of position. The design of layout-4 meets the needs of JUNO-TAO and is a compact and cheap candidate.

A prototype of tungsten pins beam dump was tested with high power electron beam at the JUDITH 2 facility. A maximum electron beam power of 40 kW was applied on a nominal beam spot area of 4 × 4 cm². This corresponds to the highest achieved beam power density of 1.4 kW/cm². Approximately 16% of the deposited energy was removed by radiation at the highest beam power values, corresponding to estimated surface temperature of ≈ 3100 K. The results of the irradiation test are presented. The further improvements of the prototype are discussed. This result provides an encouraging input for possible design of a full power beam dump for SARAF Phase II.