Two-dimensional Neutron Detector Research Articles

Orientation mapping of YbSn3 single crystals based on Bragg-dip analysis using a delay-line superconducting sensor

Recent progress in high-power pulsed neutron sources has stimulated the development of the Bragg-dip and Bragg-edge analysis methods using a two-dimensional neutron detector with high temporal resolution to resolve the neutron energy by the time-of-flight method. A delay-line current-biased kinetic inductance detector (CB-KID) is a two-dimensional superconducting sensor with a high temporal resolution and multi-hit capability. Here, it is demonstrated that a delay-line CB-KID with a 10B neutron conversion layer can be applied to high-spatial-resolution neutron transmission imaging and spectroscopy up to 100 eV. Dip structures are observed in the transmission spectra of YbSn3 single crystals, induced by Bragg diffraction and nuclear resonance absorption. The orientation mapping of YbSn3 crystals is successfully performed via the analysis of observed Bragg-dip positions in the transmission spectra.

Crystalline Orientation of CaF2 window determined by Neutron Transmission Imaging using a Delay Line Current-Biased Kinetic-Inductance Detector

The combination of a high speed two-dimensional neutron detector and an intensive pulsed neutron source provides not only neutron transmission imaging but also information on crystal structures, orientations and constituent elements by analyzing neutron transmission spectra. The delay-line current-biased kinetic-inductance detector (CB-KID) is a two-dimensional superconducting neutron detector with high spatial and temporal resolutions, and multi-hit tolerance. We demonstrated that the delay-line CB-KID with a 10B neutron conversion layer can be applied for neutron transmission measurements up to 100 keV. We observed two-different dip structures in the transmission spectra in a CaF2 single crystal, i.e., one is from the Bragg diffraction and the other is from nuclear resonance absorption. We consider that some duplicated structures in resonance absorption dips are originating from a double-bunch structure of proton pulses for producing pulsed neutrons in the accelerator.

A two-dimensional neutron detector assembly at the China Mianyang Research Reactor

A two-dimensional neutron detector consisting of 96 3He position-sensitive proportional counters was assembled at the China Mianyang Research Reactor. With a count rate limit that is higher than that of the initial multi-wire proportional chamber detector at CMRR, it will be used for the small-angle neutron scattering spectrometer Suanni. The problems caused by low air pressure and γ radiation in the working environment are pretreated, and detector performance is evaluated and compared with that of the initial proportional chamber. Now the new detector is ready to be used for Suanni.

Development of a Flat-Panel and Resistor-Type Photomultiplier Tube System for High Position-Resolution Two-Dimensional Neutron Detector

Development of a Flat-Panel and Resistor-Type Photomultiplier Tube System for High Position-Resolution Two-Dimensional Neutron Detector

Intelligent pulse light source in the performance calibration system of two-dimensional neutron detector

Chinese Spallation Neutron Source (CSNS) project will use numerous two-dimensional (2D) neutron detectors whose ZnS (Ag) scintillator is doped with 6Li. To ensure the consistency of all neutron detectors, a calibration system for the performance of 2D neutron detectors is designed. For radiation protection, the state control of the radiation source gets more and more strict. It is impossible to directly carry out experiments with massive radioactive particles. Thus, the following scheme has been designed. The controlled pulsed laser light source on a 2D mobile platform is used to replace the neutron bombardment to generate the photon. The pulse signal drives the laser diode to generate pulse light. The pulse light source located on the 2D platform is controlled by the core controller, and goes to the wavelength shift fiber through the optical fiber. The host computer (PC) receives the signal from the electronics system, processes data, and automatically calibrates the performance parameters. As shown by the experimental results, the pulse light source can perfectly meet all requirements of 2D neutron detector calibration system.

Two-dimensional imaging of charge/discharge by Bragg edge analysis of electrode materials for pulsed neutron-beam transmission spectra of a Li-ion battery

Transmission measurement of a commercial Li-ion battery was performed using the pulsed neutron beam provided by the Japan Spallation Neutron Source. A high position resolution two-dimensional neutron detector recorded the neutrons that went through the battery sample. The transmission spectra for each partitioned area on the battery sample were fitted by a function taking into account the coherent elastic scattering of neutrons on the electrode materials. Using the fitting results, we succeeded in obtaining the charge/discharge images through the quantitative crystal surface densities.

Evaluation of two-dimensional multiwire neutron detector with individual line readout under pulsed neutron irradiation

A multiwire-type, two-dimensional neutron detector system using individual line readout and optical signal transmission is developed for use in the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC). First, irradiation experiments using pulsed neutrons are performed at the J-PARC/MLF, in which the time-of-flight spectra can be measured and clear images produced. The detector system exhibits a gamma-ray sensitivity of 8.2 × 10-9, a position linearity deviation of less than 0.5%, and a spatial response of 1.8 mm full width at half maximum. Finally, the validity of the detector system is confirmed via neutron reflectometry using a Ni/Ti multilayer.

USING LIGHT TO SEE NEUTRONS AND ACCESSING THE 2D HIGH RESOLUTION: BAROTRON: A NEW PULSE FOR NEUTRON SCATTERING

Since first years of exploitation in 1960-70, neutron scattering has emerged as a unique and non-destructive means to probing inside matter properties at the nanometer length scales. Because the neutron production is scarce and expensive, the detection has to be extremely efficient. We take advantage of the recent improvements of light sensors in photon detection and detection dynamics, to develop a new type of two-dimensional neutron detector combining high detection efficiency and high spatial resolution. A prototype named Barotron (from the name of the inventor) has been built on this strategy. This 2D-neutron detector displays exceptional performances: Wide reciprocal space observation, spatial resolution lower than 0.5mm, low detection threshold (

Preliminary Experiment of Magnetic Imaging Using Polarized Pulsed Neutrons at HUNS

Imaging using polarized neutrons is one of the most attractive techniques in the neutron imaging field, because of its capability to visualize magnetic field inside materials or spaces by analyzing neutron polarization. An advanced method, which can quantify the magnetic field by combining the time-of-flight method with a polarization analysis of pulsed neutrons, has been developed at J-PARC. To introduce this method to the compact accelerator-driven neutron source, we have started the magnetic imaging experiments at Hokkaido University Neutron Source (HUNS). Using an experimental system consisting of a pair of magnetic super-mirrors as a polarizer and an analyzer, a spin flipper, and a two-dimensional neutron detector, we obtained the polarization of 90% at the wavelength over 6Å. The first demonstration experiments were performed for coil samples. As a result, an oscillatory behaviour of polarization depending on the wavelength due to the neutron spin's Larmor precession was clearly observed.

Development of two-dimensional multiwire-type neutron detector system with individual line readout and optical signal transmission

A multiwire-type two-dimensional neutron detector system with a sensitive area of 128×128mm2 is developed for use in the Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex. The system can achieve a short response time and high spatial resolution using the individual line readout method. Optical devices have been incorporated in the system for long-distance signal transmission and insulation between a detector head in the neutron shielding and signal processing circuits in the data acquisition room. The detector system exhibits a pulse-pair resolution of 1μs, an average spatial resolution of less than 2mm full width at half-maximum in the sensitive region, and a two-dimensional homogeneity of 8.3% in all pixels.

Two-dimensional Neutron Detector with GEM and its Applications

To improve material structure analysis using thermal (cold) neutrons at several pulsed neutron sources, we have developed a new gas detector for neutrons that employs a gas electron multiplier (GEM) as the detector. For neutron detection, both surfaces of a single GEM foil are coated with boron, and to increase efficiency, several GEM foils are stacked in a chamber. A prototype chamber was constructed with 10 cm × 10 cm GEM foils, and several beam tests were performed at a research reactor in Japan and at pulsed neutron sources (Hokkaido University and the Japan Proton Accelerator Research Complex). We achieved a detection efficiency of 30% for 0.22-nm thermal neutrons and a position resolution of ∼0.5 mm. In addition, we demonstrate two applications.

Simulation program for multiwire-type two-dimensional neutron detector with individual readout

We are currently developing a multiwire-type two-dimensional neutron detector system for use at the Materials and Life Science Experimental Facility at J-PARC. This system can attain a high response time and a high spatial resolution using the individual line readout method, and the performance parameters of the system strongly depend on a gas composition and pressure of a fill gas that is a gas mixture of He-3 and CF4. A simulation program for our system was developed to determine this gas condition. In addition, a small detector prototype was fabricated to evaluate the simulation program. The program involves the following calculations for each gas condition: the probability of a reaction between a neutron and He-3, the ranges of secondary particles generated by the nuclear reaction, the ejection angle of the particles, the wall effect caused by the conversion gap, and the pitch of the multiwire element. The simulation results agreed well with the experimental results obtained using the small detector prototype. Thus, it was confirmed that the simulation program can be effectively used to determine the gas composition and pressure when the required spatial resolution and detection efficiency are known.

Development of a two-dimensional neutron detector with a GEM

Development of a two-dimensional neutron detector with a GEM

Two-dimensional neutron scattering study of the bulk microstructure of polytetrafluoroethylene under uniaxial stress

The effect of a uniaxial stress on the microstructural organization of the phase IV of the bulk polytetrafluoroethylene is examined. Due to the absence of hydrogen, this semicrystalline polymer is particularly adapted to neutron scattering. The experiment was performed using a pioneering two-dimensional neutron detector Barotron, illustrating this tool benefit in this research field. It will be shown that a high degree of alignment of the crystallites is obtained from lowest elongation rates. The two-dimensional analysis distinguished the structural contributions, affected or not by the mechanical deformation, and identified the amorphous from the crystalline components of the polymer.

Optimization of a micro-strip gas chamber as a two-dimensional neutron detector using gadolinium converter

A micro-strip gas chamber (MSGC) has been under development as a two-dimensional position sensitive detector for neutron scattering experiments at the high-intensity proton accelerator facilities. The MSGC requirements as a neutron detector are high counting rate, high detection efficiency, high positional resolution, stability and large area coverage. The purpose of this paper is to verify the properties of Gadolinium as a MSGC converter. The arrangements of a capillary plate and MSGC gas pressure have been optimized by simulation of a Gadolinium converter. As a result of that, a position resolution of 160 μm and n/γ ratio of 200 were obtained at the gas pressure of 0.02 atm. In view of γ-ray sensitivity, the further improvement is required for practical applications.

A simple neutron microscope using a compound refractive lens

Images obtained with a high-magnification simple neutron microscope using a compound refractive lens are presented in this letter. The short focal length of the stack of Al biconcave lenses facilitated the setup of a simple neutron microscope at the D22 small angle scattering beam line at the Institut Laue Langevin, Grenoble, France that achieved a 35× magnification and a 214 μm resolution. Higher-resolution images could be obtained using improved neutron lens systems that enhance beam delivery from neutron sources and produce high-quality images in combination with higher resolution two-dimensional neutron detectors.

Two-dimensional gaseous microstrip detector for thermal neutrons

The two-dimensional neutron detector [1] presented here is equipped with a MicroStrip (MS) plate with an anode-cathode structure on the front side and perpendicularly placed electrodes on the back side. Its sensitive area is 80 × 80 mm 2. The substrate is the electronic conducting-glass Schott S8900. A resistive line engraved on the plate allows position localisation by charge division. The acquisition chain consists of five amplifiers and five analogue to digital converters, coupled with a multiparameter card installed in a PC. The present configuration permits an on-line acquisition of two-dimensional neutron images with a spatial resolution of 1.3 mm in both directions. The detection efficiency is 46% with a gap of 15 mm for thermal neutrons of 1.8 Å wavelength.

Two-dimensional neutron detector based on a position-sensitive photomultiplier

Abstract A new type of two-dimensional neutron scintillation detector with high spatial resolution based on a position-sensitive photomultiplier has been investigated. With a 6Li glass scintillator a spatial resolution of 1.0 mm was measured. The integral linearity over the detection area of 55 × 45 mm2 is ⩽1.5 mm. The detector homogeneity is within 10% at a discriminator level at 60% of the average peak height. The spatial resolution is expressed by a geometrical parameter which could be evaluated from light experiments and by the number of photoelectrons per neutron capture.