scholarly journals Measurement of ambient neutrons in an underground laboratory at the Kamioka Observatory

2018 ◽  
Vol 2018 (12) ◽  
Author(s):  
Keita Mizukoshi ◽  
Ryosuke Taishaku ◽  
Keishi Hosokawa ◽  
Kazuyoshi Kobayashi ◽  
Kentaro Miuchi ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Energy Spectrum ◽  
Neutron Flux ◽  
Thermal Neutron Flux ◽  
Spectral Shape ◽  
Underground Laboratory ◽  
Energy Spectra ◽  
Detector Response ◽  
Total Neutron ◽  
Important Input

Abstract Ambient neutrons are one of the most serious backgrounds for underground experiments searching for rare events. The ambient neutron flux in an underground laboratory at the Kamioka Observatory was measured using a $\mathrm{^3He}$ proportional counter with various moderator setups. Since the detector response largely depends on the spectral shape, the energy spectra of the neutrons transported from the rock to the laboratory were estimated by Monte Carlo simulations. The ratio of the thermal neutron flux to the total neutron flux was found to depend on the thermalizing efficiency of the rock. Therefore, the ratio of the count rate without a moderator to that with a moderator was used to determine this parameter. Consequently, the most likely neutron spectrum predicted by the simulations for the parameters determined by the experimental results was obtained. The result suggests an interesting spectral shape, which has not been indicated in previous studies. The total ambient neutron flux is $(23.5 \pm 0.7 \ \mathrm{_{stat.}} ^{+1.9}_{-2.1} \ \mathrm{_{sys.}}) \times 10^{-6}$ cm$^{-2}$ s$^{-1}$. This result, especially the energy spectrum information, could be a new and important input for estimating the background in current and future experiments in the underground laboratory at the Kamioka Observatory.

scholarly journals Monte-Carlo-Based Estimation of the X-ray Energy Spectrum for CT Artifact Reduction

2021 ◽  
Vol 11 (7) ◽  
pp. 3145
Author(s):  
Ehsan Nazemi ◽  
Nathanaël Six ◽  
Domenico Iuso ◽  
Björn De Samber ◽  
Jan Sijbers ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Energy Spectrum ◽  
Energy Spectra ◽  
Detector Response ◽  
Ct Scanner ◽  
Beam Hardening ◽  
Image Reconstruction Techniques ◽  
X Ray ◽  
Degrade Image Quality

Beam hardening and scattering effects can seriously degrade image quality in polychromatic X-ray CT imaging. In recent years, polychromatic image reconstruction techniques and scatter estimation using Monte Carlo simulation have been developed to compensate for beam hardening and scattering CT artifacts, respectively. Both techniques require knowledge of the X-ray tube energy spectrum. In this work, Monte Carlo simulations were used to calculate the X-ray energy spectrum of FleXCT, a novel prototype industrial micro-CT scanner, enabling beam hardening and scatter reduction for CT experiments. Both source and detector were completely modeled by Monte Carlo simulation. In order to validate the energy spectra obtained via Monte Carlo simulation, they were compared with energy spectra obtained via a second method. Here, energy spectra were calculated from empirical measurements using a step wedge sample, in combination with the Maximum Likelihood Expectation Maximization (MLEM) method. Good correlation was achieved between both approaches, confirming the correct modeling of the FleXCT system by Monte Carlo simulation. After validation of the modeled FleXCT system through comparing the X-ray spectra for different tube voltages inside the detector, we calculated the X-ray spectrum of the FleXCT X-ray tube, independent of the flat panel detector response, which is a prerequisite for beam hardening and scattering CT artifacts.

The fast neutron energy spectrum and the thermal neutron flux distribution in the experimental channel of the VVR reactor

Atomic Energy ◽  
1962 ◽  
Vol 12 (2) ◽  
pp. 127-132 ◽  
Author(s):  
N. V. Zvonov ◽  
A. I. Mis'kevich ◽  
I. V. Rogozhkin ◽  
V. I. Tereshchenko ◽  
Zh. I. Turkov ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Neutron Flux ◽  
Thermal Neutron ◽  
Fast Neutron ◽  
Neutron Energy ◽  
Flux Distribution ◽  
Thermal Neutron Flux ◽  
Neutron Energy Spectrum ◽  
Experimental Channel ◽  
Neutron Flux Distribution

scholarly journals Assessment of neutrons from secondary cosmic rays at mountain altitudes – Geant4 simulations of environmental parameters including soil moisture and snow cover

2021 ◽  
Author(s):  
Thomas Brall ◽  
Vladimir Mares ◽  
Rolf Bütikofer ◽  
Werner Rühm
Keyword(s):  
Monte Carlo ◽  
Soil Moisture ◽  
Cosmic Rays ◽  
Monte Carlo Simulations ◽  
Neutron Flux ◽  
Snow Cover ◽  
Neutron Energy ◽  
Neutron Fluence ◽  
Environmental Parameters ◽  
Total Neutron

Abstract. Ground based measurements of neutrons from secondary cosmic rays are affected by environmental parameters, particularly hydrogen content in soil. To investigate the impact of these parameters, Geant4 Monte Carlo simulations were carried out. In a previous study the model used for the Geant4 Monte Carlo simulations was already validated by measurements performed with an Extended Range Bonner Sphere Spectrometer (ERBSS) at Zugspitze, Germany, and at Jungfraujoch, Switzerland. In the present study a sensitivity analysis including different environmental parameters (i.e., slope of mountain, snow height, soil moisture, and range of albedo neutrons) and their influence on the flux of neutrons from secondary cosmic rays was performed with Geant4. The results are compared with ERBSS measurements performed in 2018 at the Environmental Research Station “Schneefernerhaus” located at the Zugspitze, Germany. It is shown that the slope of the Zugspitze mountain reduces the neutron flux from secondary cosmic rays between about 25 % and 50 % as compared to a horizontal surface, depending on neutron energy and snow cover. An increasing height of snow cover, simulated as snow water equivalent (SWE), reduces the total neutron flux exponentially down to a factor of about 2.5 as compared to soil without any snow cover, with a saturation for snow heights greater than 10 cm to 15 cm SWE, depending on neutron energy. Based on count rates measured with the individual spheres of the ERBSS, SWE values were deduced for the whole year 2018. Specifically, mean SWE values deduced for the winter months (January to March) are between 6.7 and 10.1 cm or more, while those for the summer months (July to September) are between 2.1 and 3.6 cm. Soil moisture of 5 % water mass fraction in limestone leads to a decrease of the total neutron flux by about 35 % compared to dry limestone. At a height of 1.5 m above ground, 86 % of the total albedo neutron fluence at the detector position are from a ground area with a radius of about 75 m. It is concluded that measurement of neutrons from secondary cosmic radiation can be used to gain information on height of snow cover and its seasonal changes, soil moisture, but also information on local geometry such as mountain topography. Because the influence of such parameters on neutron fluence from secondary cosmic rays depends on neutron energy, analysis of the whole neutron energy spectrum is beneficial.

scholarly journals Neutrons production on the IPHI accelerator for the validation of the design of the compact neutron source SONATE

2020 ◽  
Vol 231 ◽  
pp. 01007
Author(s):  
Hoang Ngoc Tran ◽  
Frédéric Ott ◽  
Jacques Darpentigny ◽  
Anthony Marchix ◽  
Alain Letourneau ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Neutron Flux ◽  
Neutron Scattering ◽  
Thermal Neutron ◽  
Neutron Source ◽  
Thermal Neutron Flux ◽  
Gold Foil ◽  
Proton Accelerator ◽  
Good Agreement

We aim at building a compact accelerator-based neutron source (CANS) which would provide a thermal neutron flux on the order of 4x1012 n.s-1.cm-2.sr-1. Such a brilliance would put compact neutron sources on par with existing medium flux neutron research reactors for neutron scattering experiments. We performed the first neutron production tests on the IPHI proton accelerator at Saclay at a proton energy of 3 MeV. The thermal neutron flux were measured using gold foil activation and 3He detectors. The measured flux were compared with GEANT4 Monte Carlo simulations (10.4) in which the whole experimental setup was modelled. There is a good agreement between the experimental measurements and the Monte-Carlo simulations. The available modelling tools will allow us to optimize the whole Target Moderator Reflector assembly together with the neutron scattering spectrometer geometries for the design of the neutron scattering facility SONATE.

scholarly journals Characteristics of Atmospheric Kinetic Energy Spectra during the Intensification of Typhoon Lekima (2019)

2020 ◽  
Vol 10 (17) ◽  
pp. 6029 ◽  
Author(s):  
Hepeng Zheng ◽  
Yun Zhang ◽  
Yuan Wang ◽  
Lifeng Zhang ◽  
Jun Peng ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Tropical Cyclone ◽  
Kinetic Energy ◽  
Spectral Shape ◽  
Energy Spectra ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Physical Processes ◽  
Rotational Mode ◽  
Atmospheric Energy

The intensification of Typhoon Lekima (2019) is simulated with the Weather Research and Forecasting model to study the atmospheric horizontal kinetic energy (HKE) spectra and corresponding spectral HKE budgets under the control of real tropical cyclone (TC). The results show that the TC has the ability to modify the canonical atmospheric energy spectrum during its evolution, which is dominated by its rotational mode. With the intensification of Lekima, the HKE spectrum in the troposphere swells over the central mesoscale and develops an arc-like shape. The stronger the TC, the more pronounced the arc-like shape is and the smaller scale it extends to. The roles various physical processes play at different heights and horizontal scales during the intensification of Lekima are investigated and the dependence of the effect of physical processes on scale and height is revealed. Meanwhile, the potential relationship between the intensification of TC, the activation of energy activity at smaller scales, and the downscale extension of the arc-like spectral shape is found.

scholarly journals Energy and flux measurement of the neutrons produced in a gas cell

2019 ◽  
Vol 3 ◽  
pp. 196
Author(s):  
G. Doukellis ◽  
T. Paradellis ◽  
S. Kossionides
Keyword(s):  
Monte Carlo ◽  
Energy Distribution ◽  
Neutron Flux ◽  
Semiconductor Detector ◽  
Silicon Detector ◽  
Flux Measurement ◽  
Energy Spectra ◽  
Gas Cell ◽  
Monte Carlo Techniques

The neutron flux and energy distribution of the neutrons produced in a gas cell were measured using a silicon semiconductor detector. The energy spectra produced by the borbardment of the silicon detector with neutrons were simulated using Monte Carlo techniques and were compared with the measured spectra

scholarly journals Assessment of neutrons from secondary cosmic rays at mountain altitudes – Geant4 simulations of environmental parameters including soil moisture and snow cover

2021 ◽  
Vol 15 (10) ◽  
pp. 4769-4780
Author(s):  
Thomas Brall ◽  
Vladimir Mares ◽  
Rolf Bütikofer ◽  
Werner Rühm
Keyword(s):  
Monte Carlo ◽  
Soil Moisture ◽  
Cosmic Rays ◽  
Monte Carlo Simulations ◽  
Neutron Flux ◽  
Snow Cover ◽  
Neutron Energy ◽  
Environmental Parameters ◽  
Environmental Research ◽  
Total Neutron

Abstract. Ground-based measurements of neutrons from secondary cosmic rays are affected by environmental parameters, particularly hydrogen content in soil. To investigate the impact of these parameters, in particular snow cover, Geant4 Monte Carlo simulations were carried out. In a previous study the model used for the Geant4 Monte Carlo simulations was already validated by measurements performed with an extended-range Bonner sphere spectrometer (ERBSS) at Zugspitze, Germany, and at Jungfraujoch, Switzerland. In the present study a sensitivity analysis including different environmental parameters (i.e. slope of mountain, snow height, and soil moisture) and their influence on the flux of neutrons from secondary cosmic rays was performed with Geant4. The results are compared with ERBSS measurements performed in 2018 at the Environmental Research Station Schneefernerhaus located at the Zugspitze, Germany. It is shown that the slope of the Zugspitze mountain reduces the neutron flux from secondary cosmic rays between about 25 % and 50 % as compared to a horizontal surface, depending on neutron energy and snow cover. An increasing height of snow cover, simulated as snow water equivalent (SWE), reduces the total neutron flux exponentially down to a factor of about 2.5 as compared to soil without any snow cover, with a saturation for snow heights greater than 10 to 15 cm SWE, depending on neutron energy. Based on count rates measured with the individual spheres of the ERBSS, SWE values were deduced for the whole year 2018. Specifically, mean SWE values deduced for the winter months (January to March) are between 6.7 and 10.1 cm or more, while those for the summer months (July to September) are between 2.1 and 3.6 cm. Soil moisture of 5 % water mass fraction in limestone leads to a decrease of the total neutron flux by about 35 % compared to dry limestone. It is concluded that the measurement of neutrons from secondary cosmic radiation can be used to gain information on the height of snow cover and its seasonal changes, on soil moisture, and on local geometry such as mountain topography. Because the influence of such parameters on neutron flux from secondary cosmic rays depends on neutron energy, analysis of the whole neutron energy spectrum is beneficial.

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