The description of Dynamic Albedo of Neutrons (DAN) experiment is presented, as a part of the NASA’s Mars Science Laboratory mission onboard the mars rover Curiosity. The instrument DAN includes ...Pulsing Neutron Generator (PNG) producing pulses of 14.1 MeV neutrons for irradiation of subsurface material below the rover, and Detectors and Electronics (DE) unit, which operates the instrument itself and measures the die-away time profiles of epithermal and thermal neutrons following each neutron pulse. It is shown that the DAN investigation will measure a content of hydrogen along the path of the MSL rover, and it will also provide information about a depth distribution of hydrogen at 10–20 regions selected for the detailed studies and sampling analysis.
The present paper discusses results of full-scale experimental and numerical investigations of influence of construction materials of portable pulsed neutron generators ING-031, ING-07, ING-06 and ...ING-10-20-120 (VNIIA, Russia) to their radiation characteristics formed during and after an operation (shutdown period). In particular, it is shown that an original monoenergetic isotropic angular distribution of neutrons emitted by TiT target changes into the significantly anisotropic angular distribution with a broad energy spectrum stretching to the thermal region. Along with the low-energetic neutron part, a significant amount of photons appears during the operation of generators. In the pulse mode of operation of neutron generator, a presence of the construction materials leads to the “tailing” of the original neutron pulse and the appearance of an accompanying photon pulse at ~3ns after the instant neutron pulse. In addition to that, reactions of neutron capture and inelastic scattering lead to the creation of radioactive nuclides, such as 58Co, 62Cu, 64Cu and 18F, which form the so-called activation radiation. Thus, the selection of a portable neutron generator for a particular type of application has to be done considering radiation characteristics of the generator itself. This paper will be of interest to users of neutron generators, providing them with valuable information about limitations of a specific generator and with recommendations for improving the design and performance of the generator as a whole.
The results obtained by measuring the angular and energy distributions of gamma rays originating from the inelastic scattering of 14.1-MeV neutrons by carbon and oxygen nuclei are presented. The ...measurements in question were performed by the tagged-neutron method in a beam of an ING-27 standard portable neutron generator. The angular distributions of gamma rays emitted by the 2
+
state of
12
С at 4.43 MeVand the 3
−
state of
16
O at 6.13 MeV were obtained.
3-D imaging of subsurface structure in planetary missions Litvak, M.L.; Barmakov, Y.N.; Belichenko, S.G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2020, Letnik:
963
Journal Article
Recenzirano
Ground tests using the Tagged Neutrons Method/Associated Particle Imaging methodology (TNM/API) have been conducted for a hypothetical scenario of gamma-ray measurements on the Mars surface. The main ...objective was to study applicability of TNM/API to detect heterogeneities in the subsurface under a martian lander or rover. We analyzed a possibility for identifying the soil layering structure where subsurface layers can be rich or deficit with some chemical elements. It was found that the TNM/API can be used to perform a 3-D modeling of subsurface and reveal layers enriched with carbon and layers with different concentrations of silicon.
We have conducted ground tests to study the applicability of the Tagged Neutrons Method/Associated Particle Imaging methodology (TNM/API) for the making precise gamma ray spectroscopic measurements ...onboard lander missions to the Solar system planets. Our analysis was focused on the requirement to distinguish between the spacecraft background and the subsurface signal so as to correctly evaluate the elemental composition of planetary soils. The measurements were performed in a configuration where the gamma spectrometer was surrounded by significant amounts of material that imitated a spacecraft structure. It was found that the TNM/API can substantially suppress the spacecraft background and identify the true intensities of the gamma lines attributed to major soil elements such as O, Na, Mg, Al, Si and Fe and evaluate their concentrations with an accuracy of 2–10%.
Specific features of 3-D detection arrays of plastic scintillators Bogolubov, E.P.; Koshelev, A.P.; Mikerov, V.I. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2011, Letnik:
652, Številka:
1
Journal Article
Recenzirano
This paper describes the 3-D array of scintillation detectors made of a plastic scintillator. Its operation is based on obtaining simultaneously the signal arrival time, spatial coordinates, and ...amplitude of scintillation signal produced in detection elements by radiation. Such arrays are capable of identifying and localizing neutron and gamma sources, discriminating signals from these sources, and reducing the background caused by gamma rays, cosmic-ray muons, and neutrons.
We present a summary of the physical principles and design of the Dynamic Albedo of Neutrons (DAN) instrument onboard NASA's 2009 Mars Science Laboratory (MSL) mission. The DAN instrument will use ...the method of neutron-neutron activation analysis in a space application to study the abundance and depth distribution of water in the martian subsurface along the path of the MSL rover.
The portable pulsed neutron generators developed and designed by VNIIA are presented. The neutron methods are good tools for non-destructive assay of dangerous materials. The samples of various ...systems for the detection of high explosives in luggage, identification of toxic agents in chemical munitions, and also for the prevention of illicit trafficking of fissile elements in passengers’ luggage are discussed.
The article presents main scientific tasks and description of the ADRON-LR instrument (active detector of neutrons and gamma-rays), which was developed at the IKI RAS for the Russian lunar landing ...mission
Luna-25
. The measurement technique and results are presented of ground-based experiments with models of lunar soil with different hydrogen content, which confirmed high sensitivity of the method of active neutron sensing for evaluation of water content and major elements of planetary matter.
A physical model describing in detail the process of fast neutron imaging in luminescent screens is presented. The detection quantum efficiency, luminosity and inherent spatial resolution of the ...screen were calculated using this model. Properties of transparent and disperse screens were compared. Two imaging systems were suggested to improve the detection efficiency and spatial resolution. A stack consisting of alternating neutron converters and image plates can help in obtaining both high spatial resolution and efficiency. A system containing a screen of special form and a diaphragm can be of use especially in the case of the fan beam.
