Measurement Of The High Energy Neutron Flux Above And Below Ground

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Measurement Of The High Energy Neutron Flux Above And Below Ground

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Author : Caleb Daniel Roecker
language : en
Publisher:
Release Date : 2016

Measurement Of The High Energy Neutron Flux Above And Below Ground written by Caleb Daniel Roecker and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.

High-energy neutrons produce secondary particles through spallation, which create a ubiquitous and prominent background in a wide range of rare-event particle and nuclear physics experiments. Above ground, the high-energy neutron energy-dependent flux has been measured, but with significantly varying results. Below ground, only two previous measurements have succeeded in observing these neutrons, and communicated their results in a fashion useful to others. In a separate effort, a model of the neutron energy-dependent flux was previously developed for measurements below 1000 m.w.e. No comparisons to this model and the measured neutron flux have been performed. In an effort to provide new and independent measurements above and below ground, the Multiplicity and Recoil Spectrometer (MARS) was designed, constructed, and deployed to the Kimballton Underground Research Facility (KURF). MARS is a transportable 1 m^3 detector composed of plastic scintillator Gd based neutron detectors, and a lead spallation target. MARS uses neutron spallation in the lead to transform an incident high-energy neutron into many lower energy secondary neutrons. By recording the secondary neutron multiplicity over many incident neutron events, the incident neutron energy spectrum can be inferred. This multiplicity method employed by MARS represents a new approach in high-energy neutron spectroscopy, which requires a new algorithm to correct the observed signal into a neutron spectrum. A recently developed Markov Chain Monte Carlo (MCMC) inversion algorithm, with a calibrated Monte Carlo model of MARS, is used to perform this inversion. Using this new multiplicity method, MARS performed measurements at the surface of Earth and at depths of 377 meters water equivalent (m.w.e.), 540 m.w.e., and 1450 m.w.e. Due to the transportable nature of MARS, minimal detector related systematic bias exists between these measurements. The minimal bias between these measurements at multiple depths will allow for the creation of a depth-dependent predictive model of the high-energy neutron energy-dependent flux. This dissertation introduces the new multiplicity measurement approach, the MCMC inversion algorithm, the Monte Carlo model and associated calibrations, and presents results from the four measurements. Above ground, the MARS measurement results agree with most of the previous measurements in the energy range between 90 MeV and 250 MeV. Above 250 MeV the MARS results report slightly lower flux than most of the previous measurements, but are still within the spread of all previous measurements. Below ground, no direct comparison can be made to the MARS results at 377 m.w.e. The MARS result at 540 m.w.e. appears to be in rough agreement with one of the previous below ground measurements, at the one measured energy where the results overlap. At 1450 m.w.e., the MARS results shows reasonable agreement with previous simulation predictions. The rough agreement of the MARS results, at all relevant locations, with previous measurements and existing simulation where applicable, provide confidence that all MARS measurements have produced the correct high-energy neutron energy-dependent flux. Above ground, the new independent results strengthen the results of previous measurements. Below ground, the three measurements provide consistent results with minimal detector related bias between measurements due to the transportable nature of MARS, that will be used to produce a depth-dependent model of the high-energy neutron energy-dependent flux. For the rare-event particle and nuclear physics experiments affected by high-energy neutron backgrounds, this model will allow for the prediction of the high-energy neutron background at different measurement locations, a more robust instrumental design, and the ability to estimate the high-energy neutron background contribution in their final measured data; the confidence in the results of these experiments will be improved.

Measurement Of Neutron Flux And Spectra For Physical And Biological Applications

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Author : National Committee on Radiation Protection and Measurements (U.S.)
language : en
Publisher:
Release Date : 1960

Measurement Of Neutron Flux And Spectra For Physical And Biological Applications written by National Committee on Radiation Protection and Measurements (U.S.) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1960 with Neutron flux categories.

Measurement Of Neutron And Muon Fluxes 100 M Underground With The Scibath Detector

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Author :
language : en
Publisher:
Release Date : 2014

Measurement Of Neutron And Muon Fluxes 100 M Underground With The Scibath Detector written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.

The SciBath detector is an 80 liter liquid scintillator detector read out by a three dimensional grid of 768 wavelength-shifting fibers. Initially conceived as a fine-grained charged particle detector for neutrino studies that could image charged particle tracks in all directions, it is also sensitive to fast neutrons (15-200 MeV). In fall of 2011 the apparatus performed a three month run to measure cosmic-induced muons and neutrons 100~meters underground in the FNAL MINOS near-detector area. Data from this run has been analyzed and resulted in measurements of the cosmic muon flux as \num{0.80\pm0.04}~\si{\m^{-2}\s^{-1}}, the cosmogenic fast neutron flux as \num{1.5\pm1.4e-2}~\si{\m^{-2}\s^{-1}}, and the neutron production rate from muon spallation in liquid scintillator as \num{3.8\pm3.2e-4}~$n/\mu$~\si{(\g\per\cm^2)^{-1}}. Additionally, the cosmic muon angular distribution and neutron energy distribution have been measured. These results can be extrapolated to future measurements of fast-neutron backgrounds at other underground facilities. This thesis presents a summary of the physics relevant to underground muons and fast neutrons, the SciBath detector, the analysis methodology that was used for the results presented, and comparisons between our results and those of other experiments and simulations.

Measurement Of Neutron Fluxes In The Region 30 To 500 Kev With Proportional Counters

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Author : D. H. Frisch
language : en
Publisher:
Release Date : 1946

Measurement Of Neutron Fluxes In The Region 30 To 500 Kev With Proportional Counters written by D. H. Frisch and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1946 with Neutron flux categories.

Two Neutron Energy Measurements In The Bulk Shielding Facility Using Radioactivants

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Author : J. B. Trice
language : en
Publisher:
Release Date : 1955

Two Neutron Energy Measurements In The Bulk Shielding Facility Using Radioactivants written by J. B. Trice and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1955 with Neutrons categories.

A Series Of Thermal Epithermal And Fast Neutron Measurements In The Mtr

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Author : J. B. Trice
language : en
Publisher:
Release Date : 1955

A Series Of Thermal Epithermal And Fast Neutron Measurements In The Mtr written by J. B. Trice and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1955 with Materials testing reactors categories.

Measurement Of Absorbed Dose Of Neutrons And Of Mixtures Of Neutrons And Gamma Rays

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Author : National Committee on Radiation Protection and Measurements (U.S.)
language : en
Publisher:
Release Date : 1961

Measurement Of Absorbed Dose Of Neutrons And Of Mixtures Of Neutrons And Gamma Rays written by National Committee on Radiation Protection and Measurements (U.S.) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1961 with Neutrons categories.

Measurement Of Absorbed Dose Of Neutrons And Of Mixtures Of Neutrons And Gamma Rays

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Author : National Committee on Radiation Protection and Measurements (U.S.)
language : en
Publisher:
Release Date : 1961

Measurement Of Absorbed Dose Of Neutrons And Of Mixtures Of Neutrons And Gamma Rays written by National Committee on Radiation Protection and Measurements (U.S.) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1961 with Neutrons categories.

Production Yield Of Muon Induced Neutrons In Lead

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Author : Holger Kluck
language : en
Publisher: Springer
Release Date : 2015-07-28

Production Yield Of Muon Induced Neutrons In Lead written by Holger Kluck and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-07-28 with Science categories.

The work presented in this book is a major step towards understanding and eventually suppressing background in the direct search for dark matter particles scattering off germanium detectors. Although the flux of cosmic muons is reduced by many orders of magnitude in underground laboratories, the remaining energetic muons induce neutrons through various processes, neutrons that can potentially mimic a dark matter signal. This thesis describes the measurement of muon-induced neutrons over more than 3 years in the Modane underground laboratory. The data are complemented by a thorough modeling of the neutron signal using the GEANT4 simulation package, demonstrating the appropriateness of this tool to model these rare processes. As a result, a precise neutron production yield can be presented. Thus, future underground experiments will be able to reliably model the expected rate of muon-induced neutrons, making it possible to develop the necessary shielding concept to suppress this background component.

Status Of The Dosimetry For The Radiation Effects Research Foundation Ds86

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Author : National Research Council
language : en
Publisher: National Academies Press
Release Date : 2001-10-04

Status Of The Dosimetry For The Radiation Effects Research Foundation Ds86 written by National Research Council and has been published by National Academies Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001-10-04 with Science categories.

The Committee on Dosimetry for the Radiation Effects Research Foundation (RERF) was set up more than a decade ago at the request of the U.S. Department of Energy. It was charged with monitoring work and experimental results related to the Dosimetry System 1986 (DS86) used by RERF to reconstruct the radiation doses to the survivors in Hiroshima and Nagasaki. At the time it was established, DS86 was believed to be the best available dosimetric system for RERF, but questions have persisted about some features, especially the estimates of neutrons resulting from the Hiroshima bomb. This book describes the current situation, the gamma-ray dosimetry, and such dosimetry issues as thermal-neutron discrepancies between measurement and calculation at various distances in Hiroshima and Nagasaki. It recommends approaches to bring those issues to closure and sets the stage for the recently convened U.S. and Japan Working Groups that will develop a new dosimetry for RERF. The book outlines the changes relating to DS86 in the past 15 years, such as improved numbers that go into, and are part of, more sophisticated calculations for determining the radiations from bombs that reach certain distances in air, and encourages incorporation of the changes into a revised dosimetry system.