Development of high flux thermal neutron generator for neutron activation analysis

Vainionpaa, J.H.; Chen, Allan X.; Piestrup, M. A.; Gary, C. K.; Jones, Glenn; Pantell, R. H.

doi:10.1016/j.nimb.2014.12.077

Cited by 15 publications

(7 citation statements)

References 8 publications

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“…A fast neutron-dominant window can be defined as t <1 μs from neutron creation, where only thermal neutrons from the previous pulses are present in the cavity. The neutron generator that will be used for the instrument has a pulse fall-off time in the range 10–30 μs [ 23 ]. Thus, in the simulated data, we can define a the time window t <30 μs from neutron creation, containing all the fast neutrons and a significant contribution of thermal neutrons, to provide an approximate representation of the neutron flux and gamma emissions in the instrument as the pulse switches off.…”

Section: Resultsmentioning

confidence: 99%

“…The hydrogen peak counts in the gamma-ray energy spectra from Section 3.5 can be used to estimate the measurement time requirements for hydrogen. For normal operation of the instrument, the anticipated neutron flux from the neutron generator is in the range of 1 − 5 × 10 9 neutrons/s using a pulsing frequency of approximately 1 kHz, potentially reaching up to 1 × 10 11 neutrons/s as the generator system improves [ 23 ]. With a generator flux of 1 × 10 9 neutrons/s, we extrapolate from the fitted peak area of 64±11 counts per 10 8 initial neutrons to estimate that 0.32 of data result in a 10% Poisson uncertainty contribution to the signal estimate.…”

Section: Discussionmentioning

confidence: 99%

“…The neutrons are generated isotropically and uniformly over a disk of 5 cm in diameter at the centre of the beam-facing side of the copper target disk of the instrument’s neutron generator. All neutrons are generated with an initial energy of 2.5, as would result from the deuterium-deuterium fusion reaction in the neutron generator [ 23 ]. All neutrons are created in the simulation at time t = 0 within their event.…”

Section: Methodsmentioning

confidence: 99%

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Design of a novel instrument for active neutron interrogation of artillery shells

Bélanger-Champagne

Vainionpää²,

Peura

et al. 2017

PLoS ONE

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The most common explosives can be uniquely identified by measuring the elemental H/N ratio with a precision better than 10%. Monte Carlo simulations were used to design two variants of a new prompt gamma neutron activation instrument that can achieve this precision. The instrument features an intense pulsed neutron generator with precise timing. Measuring the hydrogen peak from the target explosive is especially challenging because the instrument itself contains hydrogen, which is needed for neutron moderation and shielding. By iterative design optimization, the fraction of the hydrogen peak counts coming from the explosive under interrogation increased from % to % (statistical only) for the benchmark design. In the optimized design variants, the hydrogen signal from a high-explosive shell can be measured to a statistics-only precision better than 1% in less than 30 minutes for an average neutron production yield of 109 n/s.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Design of a novel instrument for active neutron interrogation of artillery shells

Bélanger-Champagne

Vainionpää²,

Peura

et al. 2017

PLoS ONE

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“…Neutron source, gamma ray detection system and its appropriate radiation shielding are essential components of a PGNAA facility. Different neutron sources like radioisotope neutron sources, research reactors, and accelerators were used for PGNAA [3,[7][8][9][10]. Research reactors and accelerators provide better quality for PGNAA rather than radioisotope neutron sources in less time due to higher neutron flux.…”

Section: Introductionmentioning

confidence: 99%

Feasibility study on PGNAA experiments using a prototype neutron beam at Isfahan MNSR

et al. 2023

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In this study, the feasibility study of Prompt Gamma Neutron Activation Analysis (PGNAA) experiments at Isfahan Miniature Neutron Source Reactor (MNSR) has been done using a prototype neutron beam. This neutron beam was not originally created for this purpose, but previous studies on this neutron beam have shown that it has enough neutron flux to carry out some irradiations outside the reactor core. This prototype neutron beam provided a neutron flux of order 105 n·cm-2·s-1 and a circular diameter of 5 cm for the experiments. In addition, an appropriate setup for High Purity Germanium detector (HPGe) was done at the beam outlet, where the sample is irradiated. A simple shield was also installed to prevent radiation damage to the detector. Experiments were conducted for bulk samples of salt solution with different concentrations and the prompt gamma spectrums have been obtained and analyzed.

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“…Thus, the energy spectrum of the neutron beam and the magnitudes of the neutron flux within the specific energy groups are of technical importance. Accordingly, research reactors are frequently employed owing to the high flux values [4][5][6], whereas neutrons generators are generally preferred for the mid-scale irradiation campaigns [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Neutronic Analysis of a Nuclear-Chicago NH3 Neutron Howitzer

Topuz,

Reyhancan

2018

Preprint

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Neutron howitzers are the irradiation instruments, generally used for the chemical analysis in the research laboratories, where the neutron sources are encapsulated within a moderating medium and the target materials are irradiated at the channels inserted through the corresponding neutron sources. In this study, we employ Monte Carlo simulations by using the MCNP5 code in order to perform the neutronic analysis of a Nuclear-Chicago NH3 neutron howitzer with a 5-Ci 239 Pu-Be neutron source. This neutron howitzer is a cylindrical drum that is covered by aluminum at the level of outermost layer, and the cylindrical body is filled with paraffin for the neutron moderation. The drum consists of two vertical and two horizontal irradiation channels and a vertical source channel in which the 5-Ci 239 Pu-Be neutron source is located and moved upward or downward by the aid of a plexiglass rod. We focus our study on the two horizontal irradiation channels, separated by an angle of 120 • , which are infilled with a cylindrical plexiglass bar. We construct our geometry by respecting the dimensional properties of the NH3 howitzer components and we define a biased cylindrical source of 1.02 in.×4.425 in. by taking into account the neutron energy spectrum and source strength of the 5-Ci 239 Pu-Be neutron source. We determine the neutron flux within the plexiglass bar for various energy bins in the energy range between 0 and 10.5 MeV, and also, we investigate the axial variation of the neutron flux along the plexiglass region in the horizontal irradiation channels. Our simulation results show that a significant number of thermal neutrons as well as a non-negligible population of fast neutrons propagate through the plexiglass bar, thereby demonstrating the opportunity to profit from a wide range of energy spectrum for the neutron activation analysis.

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Development of high flux thermal neutron generator for neutron activation analysis

Cited by 15 publications

References 8 publications

Design of a novel instrument for active neutron interrogation of artillery shells

Design of a novel instrument for active neutron interrogation of artillery shells

Feasibility study on PGNAA experiments using a prototype neutron beam at Isfahan MNSR

Neutronic Analysis of a Nuclear-Chicago NH3 Neutron Howitzer

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