A Systematic Study on the Neutron Skyshine from Nuclear Facilities—Part I. Monte Carlo Analysis of Neutron Propagation in Air-over-Ground Environment from a Monoenergetic Source

Nakamura, Takashi; Kosako, Toshiso

doi:10.13182/nse81-a21351

Cited by 27 publications

(7 citation statements)

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“…Figure shows the comparison of the flux of a neutron beam for different distances calculated with our simulation tool with the results presented in Figure 8 of [ Nakamura and Kosako , ]. In [ Nakamura and Kosako , ] they do not use distinct initial energies but rather energy groups. We compare a 1.5 MeV beam with a beam in energy group 14 (1–2.02 MeV) and a 150 keV beam with energy group 16 (67.4–247 keV).…”

Section: Modelsupporting

confidence: 88%

“…The simulation results and the data by Nakamura and Kosako [] for the flux r ·Φ( r ) of neutron beams of different energies E 0 as a function of distance r .…”

Section: Modelmentioning

confidence: 99%

“…Since the mass of molecular hydrogen is close to the one of a neutron, the energy transfer from a neutron to a recoiling hydrogen molecule is significant, even for small scattering angles, and the neutron loses much more energy than through the collision with air molecules. Nakamura and Kosako [1981] for the flux r ⋅ Φ(r) of neutron beams of different energies E 0 as a function of distance r.…”

Section: Neutron Cross Sectionsmentioning

confidence: 99%

“…Section 3 not only presents the attenuation of neutrons in air but also will show that the implementation of the above mentioned cross sections and algorithms yields attenuation lengths comparable to those mentioned in literature. For further validation we compare with data provided by Nakamura and Kosako [1981]. They calculate the total neutron flux r ⋅ Φ(r) of an almost monoenergetic upward directed neutron beam at distance r from the source for different initial energy groups where the flux Φ = N n ∕(4 r 2 ) is defined as the number of neutrons N n passing through a sphere with radius r. Figure 5 shows the comparison of the flux of a neutron beam for different distances calculated with our simulation tool with the results presented in Figure 8 of [Nakamura and Kosako, 1981].…”

Section: Neutron Cross Sectionsmentioning

confidence: 99%

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Production mechanisms of leptons, photons, and hadrons and their possible feedback close to lightning leaders

2017

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It has been discussed that lightning flashes emit high‐energy electrons, positrons, photons, and neutrons with single energies of several tens of MeV. In the first part of this paper we study the absorption of neutron beams in the atmosphere. We initiate neutron beams of initial energies of 350 keV, 10 MeV, and 20 MeV at source altitudes of 4 km and 16 km upward and downward and see that in all these cases neutrons reach ground altitudes and that the cross‐section areas extend to several km2. We estimate that for terrestrial gamma‐ray flashes approximately between 10 and 2000 neutrons per ms and m2 are possibly detectable at ground, at 6 km, or at 500 km altitude. In the second part of the paper we discuss a feedback model involving the generation and motion of electrons, positrons, neutrons, protons, and photons close to the vicinity of lightning leaders. In contrast to other feedback models, we do not consider large‐scale thundercloud fields but enhanced fields of lightning leaders. We launch different photon and electron beams upward at 4 km altitude. We present the spatial and energy distribution of leptons, hadrons, and photons after different times and see that leptons, hadrons, and photons with energies of at least 40 MeV are produced. Because of their high rest mass hadrons are measurable on a longer time scale than leptons and photons. The feedback mechanism together with the field enhancement by lightning leaders yields particle energies even above 40 MeV measurable at satellite altitudes.

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Section: Modelsupporting

confidence: 88%

“…The simulation results and the data by Nakamura and Kosako [] for the flux r ·Φ( r ) of neutron beams of different energies E 0 as a function of distance r .…”

Section: Modelmentioning

confidence: 99%

Section: Neutron Cross Sectionsmentioning

confidence: 99%

Section: Neutron Cross Sectionsmentioning

confidence: 99%

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Production mechanisms of leptons, photons, and hadrons and their possible feedback close to lightning leaders

2017

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“…Gui et al 13) explained in detail several approximating formulas 7,[14][15][16][17][18] of the LBRF and the CBRF for neutrons and secondary gammarays. However, the neutron energy was limited to 14 MeV in their work.…”

Section: S(e )R(e X)mentioning

confidence: 99%

Validity of the Four-Parameter Empirical Formula in Approximating the Response Functions for Gamma-ray, Neutron, and Secondary Gamma-ray Skyshine Analyses

Harima

Hirayama

Sakamoto

et al. 2003

Journal of Nuclear Science and Technology

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A four-parameter approximating formula, R= A e a x b f (x), accurately represents the skyshine line beam response function (LBRF) as a function of the distance (x) of the source-to-detector separation. Here, A is a constant for a given source energy and f (x)=e cx x dx is a damping factor. The four parameters are obtained as follows. (1) The value of parameter a corresponds to that of the LBRF at x=1 meter, which is the result of integrating the basic dose spectrum due to a single scattering particle from an emitted beam for a specified angle and a specified source energy. (2) The value of parameter b corresponds to the slope of a straight line of the response function, log R vs. log x, in the range of small distance from a source, where a single scattering particle dominates. (3) The damping factor ( f (x)) represents the attenuation trend of the LBRF at distances far from the source; the values of parameters c and d control the quantity of attenuation. The necessary reference LBRF data for point mono-directional photon source energies ranging from 0.1 to 10 MeV were generated using the EGS4 Monte Carlo code at 20 emission angles from 0.0 to 180• for 24 source-detector distances up to 2,000 m. The validity of using the four-parameter formula to interpolate the LBRF in the source-todetector distance, in the emitted angle, and in the energy was also ascertained. Furthermore, this formula was applied to the skyshine conical beam response function (CBRF) for a neutron and an associated secondary gamma-ray with the source energy ranged from thermal to 3 GeV. It was ascertained that the CBRF could be accurately approximated by an interpolation of the fitting parameters at an arbitrary distance and emitted cosine angle.

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A.1 Neutron skyshine

Fassó¹,

Göbel²,

Höfert³

et al.

Shielding Against High Energy Radiation

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A Systematic Study on the Neutron Skyshine from Nuclear Facilities—Part I. Monte Carlo Analysis of Neutron Propagation in Air-over-Ground Environment from a Monoenergetic Source

Cited by 27 publications

References 0 publications

Production mechanisms of leptons, photons, and hadrons and their possible feedback close to lightning leaders

Production mechanisms of leptons, photons, and hadrons and their possible feedback close to lightning leaders

Validity of the Four-Parameter Empirical Formula in Approximating the Response Functions for Gamma-ray, Neutron, and Secondary Gamma-ray Skyshine Analyses

A.1 Neutron skyshine

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