scholarly journals Neutron Propagation in Atmosphere

2014 ◽  
Author(s):  
John Leacock
Keyword(s):  
Neutron Propagation

scholarly journals Measurement and simulation of the neutron propagation time distribution inside a neutron monitor

2021 ◽  
pp. 102617
Author(s):  
K. Chaiwongkhot ◽  
D. Ruffolo ◽  
W. Yamwong ◽  
J. Prabket ◽  
P.-S. Mangeard ◽  
...  
Keyword(s):  
Neutron Monitor ◽  
Time Distribution ◽  
Propagation Time ◽  
Neutron Propagation

scholarly journals A new approach to search for free neutron-antineutron oscillations using coherent neutron propagation in gas

2020 ◽  
Vol 808 ◽  
pp. 135636 ◽  
Author(s):  
V. Gudkov ◽  
V.V. Nesvizhevsky ◽  
K.V. Protasov ◽  
W.M. Snow ◽  
A.Yu. Voronin
Keyword(s):  
New Approach ◽  
Free Neutron ◽  
Neutron Propagation

Neutron Propagation in Moving Matter: The Fizeau Experiment with Massive Particles

1981 ◽  
Vol 46 (24) ◽  
pp. 1551-1554 ◽  
Author(s):  
A. G. Klein ◽  
G. I. Opat ◽  
A. Cimmino ◽  
A. Zeilinger ◽  
W. Treimer ◽  
...  
Keyword(s):  
Massive Particles ◽  
Neutron Propagation

Space asymptotic method for the study of neutron propagation

2006 ◽  
Vol 33 (10) ◽  
pp. 932-940 ◽  
Author(s):  
S. Dulla ◽  
B.D. Ganapol ◽  
P. Ravetto
Keyword(s):  
Asymptotic Method ◽  
Neutron Propagation

Performance, Accuracy and Efficiency Evaluation of a Three-Dimensional Whole-Core Neutron Transport Code AGENT

2006 ◽  
Author(s):  
Tatjana Jevremovic ◽  
Mathieu Hursin ◽  
Nader Satvat ◽  
John Hopkins ◽  
Shanjie Xiao ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Neutron Transport ◽  
Three Dimensional ◽  
Open Architecture ◽  
Coarse Mesh ◽  
Research Reactors ◽  
Acceleration Techniques ◽  
Performance Accuracy ◽  
Transport Code ◽  
Neutron Propagation

The AGENT (Arbitrary GEometry Neutron Transport) an open-architecture reactor modeling tool is deterministic neutron transport code for two or three-dimensional heterogeneous neutronic design and analysis of the whole reactor cores regardless of geometry types and material configurations. The AGENT neutron transport methodology is applicable to all generations of nuclear power and research reactors. It combines three theories: (1) the theory of R-functions used to generate real three-dimensional whole-cores of square, hexagonal or triangular cross sections, (2) the planar method of characteristics used to solve isotropic neutron transport in non-homogenized 2D) reactor slices, and (3) the one-dimensional diffusion theory used to couple the planar and axial neutron tracks through the transverse leakage and angular mesh-wise flux values. The R-function-geometrical module allows a sequential building of the layers of geometry and automatic submeshing based on the network of domain functions. The simplicity of geometry description and selection of parameters for accurate treatment of neutron propagation is achieved through the Boolean algebraic hierarchically organized simple primitives into complex domains (both being represented with corresponding domain functions). The accuracy is comparable to Monte Carlo codes and is obtained by following neutron propagation through real geometrical domains that does not require homogenization or simplifications. The efficiency is maintained through a set of acceleration techniques introduced at all important calculation levels. The flux solution incorporates power iteration with two different acceleration techniques: Coarse Mesh Rebalancing (CMR) and Coarse Mesh Finite Difference (CMFD). The stand-alone originally developed graphical user interface of the AGENT code design environment allows the user to view and verify input data by displaying the geometry and material distribution. The user can also view the output data such as three-dimensional maps of the energy-dependent mesh-wise scalar flux, reaction rate and power peaking factor. The AGENT code is in a process of an extensive and rigorous testing for various reactor types through the evaluation of its performance (ability to model any reactor geometry type), accuracy (in comparison with Monte Carlo results and other deterministic solutions or experimental data) and efficiency (computational speed that is directly determined by the mathematical and numerical solution to the iterative approach of the flux convergence). This paper outlines main aspects of the theories unified into the AGENT code formalism and demonstrates the code performance, accuracy and efficiency using few representative examples. The AGENT code is a main part of the so called virtual reactor system developed for numerical simulations of research reactors. Few illustrative examples of the web interface are briefly outlined.

Updated Mapping of the Hydrogen Distribution in the Lunar Polar Regions

2020 ◽  
Author(s):  
Anton Sanin ◽  
Igor Mitrofanov ◽  
Boris Bakhtin ◽  
Maxim Litvak
Keyword(s):  
Gravitational Field ◽  
Lunar Regolith ◽  
Soil Layer ◽  
Galactic Cosmic Rays ◽  
Neutron Production ◽  
Polar Regions ◽  
Neutron Lifetime ◽  
Neutron Spectra ◽  
Subsurface Soil ◽  
Neutron Propagation

<p><span>It is well known that methods of nuclear physics allow one to study distribution of hydrogen-bearing compounds in the upper 1–2 m subsurface soil layer of atmosphereless celestial bodies or planets with thin atmospheres like Mars by measuring neutron spectra leak from the surface. For this study one needs not only to measure neutron spectra but to perform also a set of numerical simulations of the neutron production by the Galactic Cosmic Rays (GCRs) in subsurface soil, leakage of these neutrons from the surface, their transport to the neutron spectrometer on the orbit and processes of neutron interactions with the instrument’s detectors. These simulations make possible a model dependent deconvolution of the measured data to obtain the hydrogen concentration and/or other soil properties at a particular region of the planet.</span></p><p><span>Currently a number of numerical codes are being used for simulations of the neutron production and transport in planetary applications. All these codes provide a reasonable precision both in modeling of laboratory experiments and nuclear planetology tasks. However, the gravitational field description appropriate for simulation of a neutron propagation on planetary scales is not well addressed. For the planetary scales, it is not just enough to implement a uniform gravitational field (this option is available in some numerical codes). The planetary gravity should be described as a full-scale central force field with its potential depending from the distance from the center of planet. </span></p><p><span>We have developed a method of accounting effects of lunar gravity force and finite neutron lifetime on the spectral and angular distributions of neutron flux at different altitudes above Moon surface. This method was implemented to reprocess the data gathered by the collimated detectors of LEND instrument operated onboard NASA LRO spacecraft. The gravitational field description appropriate for simulation of a neutron propagation on planetary scales was not well addressed earlier. </span></p><p><span>As the result of the updated LEND data reprocessing with the discussed method, we obtained a new estimations of Water Equivalent Hydrogen (WEH) abundance in the lunar regolith and new maps of WEH distribution in the lunar polar regions. It is shown that difference of new derived values of WEH is about 0.08 wt% larger in comparison with the previously estimated value. The updated polar maps shows slightly different WEH distribution over the polar regions in comparison to the early published. The new polar maps will be used to select the landing sites of future landers.</span></p>

Neutron propagation in air at ground level

1968 ◽  
Vol 25 (2) ◽  
pp. 878-881
Author(s):  
P. A. Yampol'skii ◽  
V. F. Kokovikhin ◽  
N. A. Kondurushkin ◽  
A. V. Bolyatko
Keyword(s):  
Ground Level ◽  
Neutron Propagation
Sign in / Sign up

Export Citation Format

Share Document