4H-SiC Schottky Barrier Diodes for Efficient Thermal Neutron Detection

In this work, we present the improved efficiency of 4H-SiC Schottky barrier diodes-based detectors equipped with the thermal neutron converters. This is achieved by optimizing the thermal neutron converter thicknesses. Simulations of the optimal thickness of thermal neutron converters have been performed using two Monte Carlo codes (Monte Carlo N–Particle Transport Code and Stopping and Range of Ions in Matter). We have used 6LiF and 10B4C for the thermal neutron converter material. We have achieved the thermal neutron efficiency of 4.67% and 2.24% with 6LiF and 10B4C thermal neutron converters, respectively.

A novel method to improve the spatial resolution of GEM neutron detectors with a stopping layer

This paper proposes a novel method to improve the spatial resolution of ceramic GEM detectors by adding a stopping layer on top of the solid ¹⁰B4C neutron converter. This will restrict the emission of the secondary ion products of large angles and consequently improve the spatial resolution. The Monte Carlo program FLUKA is used to validate the method, and the verification experiments are carried out at the beam line #20 (BL20) of the China Spallation Neutron Source (CSNS). The experimental results are approximately in agreement with the simulations. The measured spatial resolution is 1.61 mm for the GEM neutron detector operated at ambient pressure with a 1-μm-thick ¹⁰B4C converter, and it is improved to ~0.8 mm by coating a 3-μm-thick titanium on top of the ¹⁰B4C converter.<br><br>

A novel method to improve the spatial resolution of GEM neutron detectors with a stopping layer

This paper proposes a novel method to improve the spatial resolution of ceramic GEM detectors by adding a stopping layer on top of the solid ¹⁰B4C neutron converter. This will restrict the emission of the secondary ion products of large angles and consequently improve the spatial resolution. The Monte Carlo program FLUKA is used to validate the method, and the verification experiments are carried out at the beam line #20 (BL20) of the China Spallation Neutron Source (CSNS). The experimental results are approximately in agreement with the simulations. The measured spatial resolution is 1.61 mm for the GEM neutron detector operated at ambient pressure with a 1-μm-thick ¹⁰B4C converter, and it is improved to ~0.8 mm by coating a 3-μm-thick titanium on top of the ¹⁰B4C converter.<br><br>

Experimental and Simulation Investigation of Micro- and Nano-Structured Neutron Detectors

We are investigating different micro- and nano-structure approaches to neutron detection based on inorganic scintillators. Specifically, we have been assessing various neutron converter-scintillator configurations through simulations and experiments. One promising inorganic scintillator is ZnO due to its relatively high light yield[1], reasonable optical transparency in the visible region[2], and relatively low refractive index[3] compared to other Zn-based crystals such as ZnS[4]. Accurate optical data and rigid simulation tools are necessary to optimize the dimensions of the neutron converter/scintillator systems. Accurate optical data are necessary since the optical parameters of a material depend on a variety of factors, including but not limited to its morphology, crystal structure, surface quality (surface roughness), as well as the temperature at which it was manufactured. Therefore, literature data show significant discrepancy when it comes to the optical parameters for the material and it is important to accurately measure these quantities for the specific sample of interest. Neutron detection is a complex process that includes neutron transport, charged particle transport, and light transport in the active detection medium. Hence, a rigid simulation tool is required to handle all these different areas of physics with sufficient accuracy. In this work, Geant4 has been chosen to carry out the simulations of these processes. Geant4 (GEometry ANd Tracking) is a toolkit used in various applications including high energy physics, astrophysics, and radiation detection[5]. The optical simulation capabilities of Geant4 have been validated by comparing the transmission and reflection data from UV-Vis spectroscopy to the Geant4 models for different Zn-based crystals. After validating the optical response of single crystals, simulation models were constructed to model more complex structures of ZnS-based alpha detection sheets (EJ-440) from Eljen Technology. Optical parameters validated with experimental results have been used in radiation simulation in Geant4. This study will serve as a basis for our ongoing effort to optimize and manufacture an efficient and compact fast neutron detection module with microand nano-structures.

Design and first tests of the S3 detector of reactor antineutrinos

The new experiment S3 devoted to the study of reactor antineutrinos was designed and constructed as a common activity of IEAP CTU in Prague and JINR (Dubna). The S3 detector is a compact, highly segmented polystyrene-based scintillating detector composed of 80 detector elements with a gadolinium neutron converter between elements layers. A positron and a neutron are produced in an inverse beta decay initiated with an electron antineutrino in the detector. A modular multi-channel fast ADC was developed for the data acquisition for the whole 80-channel S3 detector and the 4-channel cosmic veto system. The detector meets very strict safety rules of nuclear power plants and can be installed in a chamber located immediately under the reactor. The close vicinity from the reactor enables to study neutrino properties with a higher efficiency, to investigate neutrino oscillations at short baselines and try to verify the hypothesis of a sterile neutrino. The details of the design and construction of the S3 detector, as well as properties of the modular multi-channel fast ADC system, and first tests of the device are presented.

Development of the design method for the optimal design of the Neutron Converter experimental plant

The article discusses methods for optimizing the design of the Neutron Converter research plant design with parameters that are most suitable for a particular consumer. 38 similar plant structures with different materials and sources were calculated, on the basis of which the most optimal options were found. As part of the interaction between OKBM Afrikantov JSC and the Nizhny Novgorod State Technical University named after R. E. Alekseev, the Neutron Converter research plant was designed and assembled. The universal neutron converter is a device for converting a stream of fast neutrons emitted by isotopic sources into a "standardized" value of flux density with known parameters in the volume of the central part of the product, which is the working part of the universal neutron converter. To supply neutron converters to other customer organizations (universities, research organizations and collective centers), it is necessary to take into account the experience of operating an existing facility, as well as rationalize the design process of each specific instance in accordance with the requirements of the customer.

THERMAL AND FAST NEUTRON DOSE EQUIVALENT DISTRIBUTION MEASUREMENT OF 15-MV LINEAR ACCELERATOR USING A CR-39 NUCLEAR TRACK DETECTORS

The main purpose of this study is to measure the contribution of the thermal and fast neutron dose along the central axis of the 15 MV Elekta Precise linac in a tissue equivalent phantom. In order to achieve this purpose, different points were selected in three field sizes of 5 × 5 cm2, 10 × 10 cm2 and 15 × 15 cm2. Fast and thermal neutrons were measured using CR-39 nuclear track detectors with and without thermal neutron converter of 10B, respectively. According to the results, the fast neutron dose equivalent was decreased as the depth increased (field size 5 × 5, 10 × 10 and 15 × 15 cm2 fall from 0.35 to 0.15, 0.5 to 0.3 and 0.5 to 0.3, respectively). Thermal dose equivalent was increased as the depth increased in the tissue equivalent phantom (field size 5 × 5, 10 × 10 and 15 × 15 cm2 rise from 0.1 to 0.4, 0.4 to 0.8 and 0.4 to 0.9, respectively). In conclusion, at depth &lt;3 cm, most existing neutrons are fast and CR-39 films are sensitive to fast neutrons; therefore, they are more appropriate than thermoluminescent dosemeters in measuring neutron dose equivalent.