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In fusion plasmas, essential plasma parameters can be inferred from x-ray and neutron measurements. The analysis of emitted neutron spectra can give access to the fuel ion ratio and ion temperature, while the local x-ray plasma emissivity contains information about electron temperature, magnetic axis, and concentration of impurities that can be estimated with the help of dedicated tomographic inversion and synthetic diagnostic tools. We report on ongoing efforts dedicated to x-ray and neutron diagnostics of tokamak plasmas. A methodology to determine the core impurity concentration and electron temperature from multiple line-integrated x-ray measurements in different energy bands is introduced. It is first validated with synthetic measurements and then applied on WEST experimental data. Regarding neutron measurements, a thin-foil proton recoil spectrometer using a gas electron multiplier (GEM) detector is being developed to measure fast neutron energy spectra. The modeling of the energy response function of this NS-GEM prototype, intended for future applications of fusion plasma spectrometry, is presented and discussed. [ABSTRACT FROM AUTHOR]

Plastic organic scintillators such as the blue-emitting BCF-12 are versatile and inexpensive tools. Recently, BCF-12 scintillators have been foreseen for investigation of the spatial distribution of neutrons emitted from dense magnetized plasma. For this purpose, small-area (5 mm × 5 mm) detectors based on BCF-12 scintillation rods and Hamamatsu photomultiplier tubes were designed and constructed at the Institute of Nuclear Physics. They will be located inside the neutron pinhole camera of the PF-24 plasma focus device. Two different geometrical layouts and approaches to the construction of the scintillation element were tested. The aim of this work was to determine the efficiency of the detectors. For this purpose, the experimental investigations using a neutron generator and a Pu–Be source were combined with Monte Carlo computations using the Geant4 code. [ABSTRACT FROM AUTHOR]

We present cases of so-called artifacts observed in the response of neutron detectors in the vicinity of formation boundaries (e.g., in neutron logging for geophysical prospecting). The appearance of artifacts is related mainly to differences in the neutron transport properties of adjacent media: the fast neutron slowing-down length and the absorption cross section of thermal neutrons. The basis for examining the causes of the appearance of artifacts on the profiling curve was a numerical experiment consisting of our measuring the counts of the thermal neutron detector of the neutron probe under given measurement conditions in the well. The detector response was determined with a 1 cm step in the vicinity of the border of two geological formations, significantly different in terms of neutron parameters, which allowed accurate registration of artifacts on the logging curve. The numerical code MCNP6 with the ENDF B-VII.1 data library was used to solve neutron transport problems in complex systems and to explain the presence of artifacts on the basis of the physics of neutron transport and the spatial-energy distribution of neutron fields in the vicinity of formation boundaries., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The paper presents an analysis and discussion of the problem of underestimation of neutron signal amplitude in profiling of the thin-layers rock media. The corresponding neutron profiles were modeled using the Monte Carlo method, and the formalism of the general neutron parameter GNP was used to analyze the results. We show that the degradation of the thin layer signal amplitude depends on the layer thickness, and on the difference in the neutron properties of the layer and its surrounding medium., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

A signal of a spectrometric gamma-gamma density tool in specific borehole conditions has been numerically calculated. Transport of gamma rays, from a point (137)Cs gamma source situated in a borehole tool, through rock media to detectors, has been simulated using a Monte Carlo code. The influence of heterogeneity of the rock medium surrounding the borehole on the signal of the detectors has been examined. This heterogeneity results from the presence of an interface between two different geological layers, parallel to the borehole wall. The above conditions may occur in horizontal logging, when the borehole is drilled along the boundary of geological layers. It is possible to assess the distance from the boundary on the basis of the responses of the gamma-gamma density tool, using the classic interpretation "spine & ribs" procedure. The effect of different densities of the bordered layers on the tool response has been analyzed. The presented calculations show the wide possibilities of numerical modeling of the complex borehole geometry and solving difficult interpretation problems in nuclear well logging., (Copyright © 2010 Elsevier Ltd. All rights reserved.)