The diffraction detector for the EMD of the CSNS

On 23rd August 2018, the China Spallation Neutron Source (CSNS) located in Dongguan operated 4 neutron instruments. In the future, twenty neutron spectrometers will be built to provide multidisciplinary platforms for scientific research by national institutions, universities, and industries. Engineering Material Diffractometer (EMD), which will be used for strain measurements in engineering materials and components, will be constructed at the Beamline 8 in 2022. A novel thermal neutron detector, which will comply with the requirements of EMD application, is being developed. This detector will consist of 6LiF/ZnS(Ag) scintillation screens, wavelength shifting fiber (WLSF) arrays, a silicon photomultiplier (SiPM) and Application Specific Integrated Circuit (ASIC) read-out electronics. Each scintillation screen will be inclined with respect to the incident neutron beam at a grazing angle θ = 17°. Such geometry will not only improve the spatial resolution of detectors but also the neutron detection efficiency. The prototype of detector module has been tested at the neutron Beamline 20 at the CSNS. The experimental results obtained for this prototype illustrate that the pixel size of detector module is 3 mm and the detection efficiency exceeds 40% at the neutron wavelength of 1 Å. Based on these results, we design and manufacture the final version of the detector for the EMD application, which is characterized by low power consumption, highly integrated and easy to install. 70 such detectors will be installed till the end of 2021.

Development and performance evaluation of a multi-layer boron-lined detector for the CPHS-SANS instrument

A position-sensitive thermal neutron detector module based on multi-layer boron-lined tubes has been developed. It is designed for the CPHS (compact pulsed hadron source) SANS (small-angle neutron scattering) instrument [Loong et al. (2012). Phys. Procedia, 26, 8–18]. The detector module consists of 64 boron-lined tubes, arranged into an eight row by eight column structure. Several key aspects of the development of the detector prototype are briefly covered, including the detector module structure design, the readout electronic system and the digital filter of neutron waveforms. Preliminary characterization reveals that the detector module could achieve an average axial spatial resolution of 5.62 mm and a good position linearity. The detection efficiency measurement shows that more than 30% efficiency can be achieved for thermal neutrons on the CPHS. A virtual experiment was conducted to evaluate the performance of the multi-layer boron-lined tubes in SANS measurement; the effect of inside detector scattering of the multi-layer detector was simulated. The result shows that, by implementing proper data reduction, the impact of inside detector scattering on the Q (momentum transfer) value and Q resolution is negligible.

Scintillating thermal neutron detectors for cosmic ray soil moisture monitoring

Cosmic Ray Neutron Sensing (CRNS) is a powerful technique that allows non-invasive monitoring of soil moisture on length scales well matched for agricultural applications. One factor limiting the use of the technique within industrial agriculture settings is the high initial cost of Helium-3 or BF3 tubes typically used for ground level neutron monitoring. This paper discusses the use of Geant4 to design and optimise an alternative scintillator based epi-thermal neutron detector that may be applicable for challenges where cost is a higher driving factor than temporal resolution.

Calculation of response functions for cylindrical nested neutron spectrometer

In a recent work, a new neutron spectrometer, namely Cylindrical Nested Neutron Spectrometer (CNNS). It works under the same principles as a Bonner Sphere Spectrometer (BSS), except that different amounts of moderator around a thermal neutron detector are configured by adding or removing cylindrical shells. The CNNS consists of a 4mm x 4mm 6LiI(Eu) scintillator crystal and nested cylindrical polyethylenemoderators. The objective of this paper is describing the use of MCNPX code for determining a optimal ratio between height and diameter of the moderators in order to remain isotropic angular response to neutrons like BSS and determining of response functions for moderators of different diameters at 104 energy points from 0.001 eV to 19.95 MeV.

MBGEM: a stack of borated GEM detector for high efficiency thermal neutron detection

A new position-sensitive thermal neutron detector based on boron-coated converters has been developed as an alternative to today’s standard $$^3\mathrm{He}$$ 3 He -based technology for application to thermal neutron scattering. The key elements of the development are the boron-coated GEM foils (Sauli in Nucl Instrum Methods Phys Res Sect A Accel Spectrom Detect Assoc Equip 386:531, 1997) that are used as a multi-layer neutron converter via the $$^{10}\mathrm{B}(n,\alpha )^7\mathrm{Li}$$ 10 B ( n , α ) 7 Li reaction together with an efficient collection of the produced secondary electrons. This paper reports the test performed on a 3 layers converter prototype coupled to a GEMPix detector (Murtas in Radiat Meas 138:106421, 2020), carried out in order to study the possibility to produce a large-scale multi-layer neutron detector capable to reach high detection efficiency with high spatial resolution and able to sustain the high neutron flux expected in the new neutron spallation source under development like the ESS.

Nanometer-Sized Boron Loaded Liposomes Containing Fe3O4 Magnetic Nanoparticles and Tributyl Borate and Anti-Albumin from Bovine Serum Antibody for Thermal Neutron Detection

A shortage in the supply of 3He used for thermal neutron detector makes researchers to find 3He alternatives for developing new neutron detectors. Here, we prepared a neutron-sensitive composite liposome with tributyl borate and encapsulating with Fe3O4@oleic acid nanoparticles (Fe3O4@OA NPs), methylene blue (MB), or anti-albumin from bovine serum (anti-BSA). The tributyl borate compound was characterized by Fourier transform infrared spectroscopy (FT-IR). In addition, the morphology, element compositions, and magnetic properties of the composite liposome were investigated with transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and vibrating sample magnetometer (VSM), respectively. The results indicated that a typical ellipsoidal magnetic liposome structure was obtained, and the lengths of the minor axis and major axis were 49 ± 1 nm and 87 ± 3 nm, respectively. Under thermal neutron irradiation, the structure of composite liposome was destroyed, and encapsulated reporter molecules were released, which was detected by ultraviolet–visible (UV–vis) spectroscopy and surface plasmon resonance (SPR) technology. The response of this sensor based on a destructive assay shows a good correlation with neutron doses. Besides, the sensor has a neutron to gamma-ray rejection ratio of 1568 at a thermal neutron flux rate of 135.6 n/cm2·s, which makes it a promising alternative to 3He.