Dissertations / Theses: 'Neutron flux measurement'

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Negoita, Cezar Ciprian. "Measurement of neutron flux spectra in a Tungsten Benchmark by neutron foil activation method." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1096547324156-18744.

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The nuclear design of fusion devices such as ITER (International Thermonuclear Experimental Reactor), which is an experimental fusion reactor based on the "tokamak" concept, rely on the results of neutron physical calculations. These depend on the knowledge of the neutron and photon flux spectra which is particularly important because it permits to anticipate the possible answers of the whole structure to phenomena such as nuclear heating, tritium breeding, atomic displacements, radiation shielding, power generation and material activation. The flux spectra can be calculated with transport codes, but validating measurements are also required. An important constituent of structural materials and divertor areas of fusion reactors is tungsten. This thesis deals with the measurement of the neutron fluence and neutron energy spectrum in a tungsten assembly by means of multiple foil neutron activation technique. In order to check and qualify the experimental tools and the codes to be used in the tungsten benchmark experiment, test measurements in the D-T and D-D neutron fields of the neutron generator at Technische Universität Dresden were performed. The characteristics of the D-D and D-T reactions, used to produce monoenergetic neutrons, together with the selection of activation reactions suitable for fusion applications and details of the activation measurements are presented. Corrections related to the neutron irradiation process and those to the sample counting process are discussed, too. The neutron fluence and its energy distribution in a tungsten benchmark, irradiated at the Frascati Neutron Generator with 14 MeV neutrons produced by the T(d, n)4He reaction, are then derived from the measurements of the neutron induced &#947;-ray activity in the foils using the STAYNL unfolding code, based on the linear least-square-errors method, together with the IRDF-90.2 (International Reactor Dosimetry File) cross section library. The differences between the neutron flux spectra measured by means of neutron foil activation and the neutron flux spectra obtained in the same assembly, making use of an NE213 liquid-scintillation spectrometer were studied. The comparison of measured neutron spectra with the spectra calculated with the MCNP-4B (Monte Carlo neutron and photon transport) code, which allows a crucial test of the evaluated nuclear data used in fusion reactor design, is discussed, too. In conclusion, this thesis shows the applicability of the neutron foil activation technique for the measurement of neutron flux spectra inside a thick tungsten assembly irradiated with 14 MeV from a D-T generator
Die Konstruktion von Fusionsreaktoren wie ITER (International Thermonuclear Experimental Reactor), der ein experimenteller Fusionsreaktor ist und auf dem "Tokamak"-Konzept beruht, basiert unter neutronenphysikalischen Gesichtspunkten auf den Ergebnissen von umfangreichen Simulationsrechnungen. Diese setzen die Kenntnis der Spektren des Neutronen- und Photonenflusses voraus die besonders wichtig ist, weil sie, die möglichen Antworten der ganzen Struktur auf physikalische Prozesse vorauszuberechnen erlaubt wie z.B.: Heizen durch nukleare Prozesse, Tritium-Brüten, Atomverschiebung, Abschirmung von Strahlung, Leistungserzeugung und Materialaktivierung. Die Flußspektren können mittels Transportcodes berechnet werden, aber es werden auch Messungen zu ihrer Bestätigung benötigt. Ein wichtiger Bestandteil des Strukturmaterials und der Divertor-Flächen der Fusionsreaktoren ist Wolfram. Diese Dissertation behandelt die Messungen der Neutronspektren und ?fluenz in einer Wolfram-Anordnung mittels der Multifolien-Neutronenaktivierungstechnik. Um die anzuwendenden experimentellen Geräte und die Codes, die im Wolfram-Benchmark-Experiment eingesetzt werden, zu überprüfen und zu bestimmen, wurden Testmessungen in den D-T und D-D Neutronenfeldern des Neutronengenerator der Technischen Universität Dresden durchgeführt. Die Eigenschaften der D-T und D-D Reaktionen, die für die Erzeugung von monoenergetischen Neutronen verwendet werden, sowie die Auswahl der Aktivierungsreaktionen, die für Fusionsanwendungen geeignet sind und die Aktivierungsmessung werden detailliert vorgestellt. Korrekturen, die sich auf den Neutronen-Bestrahlungsprozess und auf den Probenzählungsprozess beziehen, werden ebenfalls besprochen. Die Neutronenfluenz und ihre Energieverteilung in einem Wolfram-Benchmark, bestrahlt am Frascati Neutronen Generator mit 14 MeV-Neutronen aus der T(d, n)4He Reaktion, werden aus den Messungen der &#947;-Strahlenaktivität, die von Neutronen in den Folien induziert ist, durch den STAYNL Entfaltungscode, der auf der Methode der kleinsten Fehlerquadrate basiert, zusammen mit der IRDF-90.2 Wirkungsquerschnitt-Bibliothek abgeleitet. Die Unterschiede zwischen den Neutronenflußspektren, die mit Hilfe der Multifolien-Neutronenaktivierung ermittelt wurden, und den Neutronenflußspektren, gemessen im selben Aufbau mit einem NE-213 Flüssigszintillator, wurden untersucht. Die gemessenen Neutronenspektren werden den aus MCNP-4B Rechnungen (Monte Carlo neutron and photon transport) ermittelten Spektren gegenüber gestellt. Der Vergleich stellt einen wichtigen Test der evaluierten Kerndaten für Fusionsreaktorkonzepte dar. Zusammenfassend zeigt diese Arbeit die Anwendbarkeit der Multifolien-Neutronenaktivierungstechnik bei Messungen der Neutronenflussspektren innerhalb eines massiven Wolframblocks bei Bestrahlung mit schnellen Neutronen aus D-T Generatoren

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2

Negoita, Cezar C. [Verfasser]. "Measurement of Neutron Flux Spectra in a Tungsten Benchmark by Neutron Foil Activation Method / Cezar C Negoita." Aachen : Shaker, 2004. http://d-nb.info/1186575115/34.

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3

PERSIANI, RINO. "Measurement of the muon-induced neutron flux at LNGS with the LVD experiment." Doctoral thesis, Università degli studi di Catania, 2011. http://hdl.handle.net/20.500.11769/538580.

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Persiani, Rino <1980&gt. "Measurement of the muon-induced neutron flux at LNGS with the LVD experiment." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3897/1/persiani_rino_tesi.pdf.

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In this thesis we describe in detail the Monte Carlo simulation (LVDG4) built to interpret the experimental data collected by LVD and to measure the muon-induced neutron yield in iron and liquid scintillator. A full Monte Carlo simulation, based on the Geant4 (v 9.3) toolkit, has been developed and validation tests have been performed. We used the LVDG4 to determine the active vetoing and the shielding power of LVD. The idea was to evaluate the feasibility to host a dark matter detector in the most internal part, called Core Facility (LVD-CF). The first conclusion is that LVD is a good moderator, but the iron supporting structure produce a great number of neutrons near the core. The second conclusions is that if LVD is used as an active veto for muons, the neutron flux in the LVD-CF is reduced by a factor 50, of the same order of magnitude of the neutron flux in the deepest laboratory of the world, Sudbury. Finally, the muon-induced neutron yield has been measured. In liquid scintillator we found $(3.2 \pm 0.2) \times 10^{-4}$ n/g/cm$^2$, in agreement with previous measurements performed at different depths and with the general trend predicted by theoretical calculations and Monte Carlo simulations. Moreover we present the first measurement, in our knowledge, of the neutron yield in iron: $(1.9 \pm 0.1) \times 10^{-3}$ n/g/cm$^2$. That measurement provides an important check for the MC of neutron production in heavy materials that are often used as shield in low background experiments.

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5

Persiani, Rino <1980&gt. "Measurement of the muon-induced neutron flux at LNGS with the LVD experiment." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3897/.

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In this thesis we describe in detail the Monte Carlo simulation (LVDG4) built to interpret the experimental data collected by LVD and to measure the muon-induced neutron yield in iron and liquid scintillator. A full Monte Carlo simulation, based on the Geant4 (v 9.3) toolkit, has been developed and validation tests have been performed. We used the LVDG4 to determine the active vetoing and the shielding power of LVD. The idea was to evaluate the feasibility to host a dark matter detector in the most internal part, called Core Facility (LVD-CF). The first conclusion is that LVD is a good moderator, but the iron supporting structure produce a great number of neutrons near the core. The second conclusions is that if LVD is used as an active veto for muons, the neutron flux in the LVD-CF is reduced by a factor 50, of the same order of magnitude of the neutron flux in the deepest laboratory of the world, Sudbury. Finally, the muon-induced neutron yield has been measured. In liquid scintillator we found $(3.2 \pm 0.2) \times 10^{-4}$ n/g/cm$^2$, in agreement with previous measurements performed at different depths and with the general trend predicted by theoretical calculations and Monte Carlo simulations. Moreover we present the first measurement, in our knowledge, of the neutron yield in iron: $(1.9 \pm 0.1) \times 10^{-3}$ n/g/cm$^2$. That measurement provides an important check for the MC of neutron production in heavy materials that are often used as shield in low background experiments.

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6

Medina, Ricardo. "Measurement of neutron flux and spectrum-averaged cross sections for an in-pile PWR loop." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/14095.

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TARDELLI, TIAGO C. "Avaliação de dados nucleares para dosimetria de nêutrons." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10587.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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CAVALIERI, TASSIO A. "Emprego do NCNP no estudo dos TLDs 600 e 700 visando a implementação da caracterização do feixe de irradiação na instalação de BNCT do IEA-R1." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10565.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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9

Montagu, Thierry. "Transformées stabilisatrices de variance pour l'estimation de l'intensité du Shot Noise : application à l'estimation du flux neutronique." Electronic Thesis or Diss., Université Côte d'Azur, 2024. http://www.theses.fr/2024COAZ5015.

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Le Shot Noise est un processus aléatoire qui permet notamment de modéliser fidèlement le nombre d'occurrences des interactions entre particules physiques et leurs détecteurs associés ; ce nombre définit l'intensité du processus. Lorsque l'intensité est faible, il est possible d'individualiser les interactions dont les temps d'arrivées sont modélisés par le processus de Poisson. Dans le cas contraire, les évènements ne sont plus discernables (ils « s'empilent »), mais le théorème de Campbell - qui établit les cumulants du ShotNoise - permet de remonter à l'intensité du processus. L'estimation des deux premiers cumulants est réalisée grâce à la moyenne et à la variance empiriques de trajectoires du Shot Noise. Il est remarqué que les variances de ces estimateurs et des estimateurs de l'intensité du Shot Noise correspondants dépendent de leurs moyennes respectives. Cette propriété d'hétéroscédasticité étant observée en théorie et en pratique, une approche par transformées stabilisatrices de variance est proposée via la Delta method. Celles-ci sont calculées ainsi que leur biais, et les transformées inverses associées. Leurs propriétés asymptotiques sont vérifiées par des simulations numériques. Dans le cadre applicatif des mesures de flux neutroniques qui reposent sur l'estimation des deux premiers cumulants du Shot Noise et qui ont également pour finalité l'estimation de l'intensité du processus aléatoire, des transformées stabilisatrices de variance sont spécifiquement établies ainsi que leurs biais et leurs transformées inverses. Elles sont finalement combinées à un filtre de Kalman adaptatif pour débruiter le flux neutronique. Des simulations sont menées pour caractériser les performances de filtrage. Le débruitage de signaux réels est également réalisé
The Shot noise is a random process that can be used to accurately model the numberof occurrences of physical particles impinging their associated detectors ; this numberis referred to as the intensity of the process. When this number is small, it is possible to individualize the recorded events whose arrival times are modelled thanks to the Poisson process. In the opposite case, the events are no longer discernible (they ”pile up”), but Campbell's theorem - which establishes the cumulants of the Shot Noise - still allows to estimate the intensity of the process. The estimation of the two first cumulants is classically achevied with the empirical mean and the empirical variance. It is noted in this work, that the variances of theses two estimators and their corresponding estimators of the Shot Noise intensity are functions of their respective means. This property ofheter heteroscedasticity being observed both in theory and practice, an approach by variance stabilizing transforms is proposed using the "Delta method". These are calculated as well as their bias, and their corresponding inverse transforms. Their asymptotic properties are verified thanks to numerical simulations. In the applicative context of neutron flux measurements, which rely on the estimation of the first two cumulants of the Shot Noise and which also have the purpose of estimating the intensity of this random process,variance stabilizing transforms are specifically established as well as their biases and their inverse transforms. They are finally combined with an adaptive Kalman filter in order to denoise the neutron flux measurements. Numerical simulations are carried out to assessfiltering performances. Denoising of real signals is also performed

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CHIESA, DAVIDE. "Development and experimental validation of a Monte Carlo simulation model for the Triga Mark II reactor." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/50064.

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In recent years, many computer codes, based on Monte Carlo methods or deterministic calculations, have been developed to separately analyze different aspects regarding nuclear reactors. Nuclear reactors are very complex systems, which require an integrated analysis of all the variables which are intrinsically correlated: neutron fluxes, reaction rates, neutron moderation and absorption, thermal and power distributions, heat generation and transfer, criticality coefficients, fuel burnup, etc. For this reason, one of the main challenges in the analysis of nuclear reactors is the coupling of neutronics and thermal-hydraulics simulation codes, with the purpose of achieving a good modeling and comprehension of the mechanisms which rule the transient phases and the dynamic behavior of the reactor. This is very important to guarantee the control of the chain reaction, for a safe operation of the reactor. In developing simulation tools, benchmark analyses are needed to prove the reliability of the simulations. The experimental measurements conceived to be compared with the results coming out from the simulations are really precious and can provide useful information to improve the description of the physics phenomena in the simulation models. My PhD research activity was held in this framework, as part of the research project Analysis of Reactor COre (ARCO, promoted by INFN) whose task was the development of modern, flexible and integrated tools for the analysis of nuclear reactors, relying on the experimental data collected at the research reactor TRIGA Mark II, installed at the Applied Nuclear Energy Laboratory (LENA) at the University of Pavia. In this way, once the effectiveness and the reliability of these tools for modeling an experimental reactor have been demonstrated, these could be applied to develop new generation systems. In this thesis, I present the complete neutronic characterization of the TRIGA Mark II reactor, which was analyzed in different operating conditions through experimental measurements and the development of a Monte Carlo simulation tool (relied on the MCNP code) able to take into account the ever increasing complexity of the conditions to be simulated. First of all, after giving an overview of some theoretical concepts which are fundamental for the nuclear reactor analysis, a model that reconstructs the first working period of the TRIGA Mark II reactor, in which the “fresh” fuel was not heavily contaminated with fission reaction products, is described. In particular, all the geometries and the materials are described in the MCNP simulation model with good detail, in order to reconstruct the reactor criticality and all the effects on the neutron distributions. The very good results obtained from the simulations of the reactor at low power condition -in which the fuel elements can be considered to be in thermal equilibrium with the water around them- are then used to implement a model for simulating the full power condition (250kW), in which the effects arising from the temperature increase in the fuel-moderator must be taken into account. The MCNP simulation model was exploited to evaluate the reactor power distribution and a dedicated experimental campaign was performed to measure the water temperature within the reactor core. In this way, through a thermal-hydraulic calculation tool, it has been possible to determine the temperature distribution within the fuel elements and to include the description of the thermal effects in the MCNP simulation model. Thereafter, since the neutron flux is a crucial parameter affecting the reaction rates and thus the fuel burnup, its energy and space distributions are analyzed presenting the results of several neutron activation measurements. Particularly, the neutron flux was firstly measured in the reactor's irradiation facilities through the neutron activation of many different isotopes. Hence, in order to analyze the energy flux spectra, I implemented an analysis tool, based on Bayesian statistics, which allows to combine the experimental data from the different activated isotopes and reconstruct a multi-group flux spectrum. Subsequently, the spatial neutron flux distribution within the core was measured by activating several aluminum-cobalt samples in different core positions, thus allowing the determination of the integral and fast flux distributions from the analysis of cobalt and aluminum, respectively. Finally, I present the results of the fuel burnup calculations, that were performed for simulating the current core configuration after a 48 years-long operation. The good accuracy that was reached in the simulation of the neutron fluxes, as confirmed by the experimental measurements, has allowed to evaluate the burnup of each fuel element from the knowledge of the operating hours and the different positions occupied in the core over the years. In this way, it has been possible to exploit the MCNP simulation model to determine a new optimized core configuration which could ensure, at the same time, a higher reactivity and the use of less fuel elements. This configuration was realized in September 2013 and the experimental results confirm the high quality of the work done. The results of this Ph.D. thesis highlight that it is possible to implement analysis tools -ranging from Monte Carlo simulations to the fuel burnup time evolution software, from neutron activation measurements to the Bayesian statistical analysis of flux spectra, and from temperature measurements to thermal-hydraulic models-, which can be appropriately exploited to describe and comprehend the complex mechanisms ruling the operation of a nuclear reactor. Particularly, it was demonstrated the effectiveness and the reliability of these tools in the case of an experimental reactor, where it was possible to collect many precious data to perform benchmark analyses. Therefore, for as these tools have been developed and implemented, they can be used to analyze other reactors and, possibly, to project and develop new generation systems, which will allow to decrease the production of high-level nuclear waste and to exploit the nuclear fuel with improved efficiency.

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Raaf, Jennifer Lynne. "A Measurement of the Neutrino Neutral Current π⁰ Cross Section at MiniBooNE." Cincinnati, Ohio : University of Cincinnati, 2005. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1116006438.

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Thesis (Ph. D.)--University of Cincinnati, 2005.
Title from electronic thesis title page (viewed Jul. 11, 2006). Includes abstract. Keywords: neutrino; neutral current; cross section; single pion; resonant; coherent; flux-averaged. Includes bibliographical references.

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Giuliano, Dominic Richard. "Neutron Flux Measurements and Calculations in the Gamma Irradiation Facility Using MCNPX." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282570075.

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Cox-Mobrand, Gary A. "Data integrity and electronic calibrations for the neutral current detector phase measurement of the 8B solar neutrino flux at the Sudbury Neutrino Observatory /." Thesis, Connect to this title online; UW restricted, 2008. http://hdl.handle.net/1773/9647.

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Versari, Federico <1992&gt. "Measurement of the atmospheric electron and muon neutrino flux with the ANTARES neutrino telescope." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amsdottorato.unibo.it/9664/1/PhD_Thesis____.pdf.

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This thesis presents a combined measurement of the energy spectra of atmospheric electron and muon neutrinos in the energy range between around 100 GeV and 50 TeV with the ANTARES neutrino telescope. The analysis uses 3012 days of detector livetime in the period from 2007 to 2017, and selects 1016 neutrino interacting in (or close to) the instrumented volume of the detector, yielding shower-like events and starting track events. The contamination by atmospheric muons is suppressed at the level of a few per mill by different steps in the selection analysis, including a Boosted Decision Tree classifier. The distribution of reconstructed events is unfolded in terms of electron and muon neutrino fluxes and the derived energy spectra are compared with previous measurements.

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15

George, Tyrel Daniel Frank. "Design and testing of long-lifetime active sensor arrays for in-core multi-dimensional flux measurements." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/35229.

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Master of Science
Department of Mechanical and Nuclear Engineering
Douglas S. McGregor
Fission chambers are a common type of detector used to determine the neutron flux and power of a nuclear reactor. Due to the limited space and high neutron flux in a reactor core, it is difficult to perform real-time flux measurements with present-day in-core instrumentation. Micro-pocket fission detectors, or MPFDs, are relatively small in size and have low neutron sensitivity while retaining a large neutron to gamma ray discrimination ratio, thereby, allowing them to be used as active neutron flux monitors inside a nuclear reactor core. The micro-pocket fission chamber allows for multiple detectors to be inserted into a flux port or other available openings within the nuclear reactor core. Any material used to construct the MPFD must be rugged and capable of sustaining radiation damage for long periods of time. Each calibrated MPFD provides measurements of the flux for a discrete location. The size of these detectors allows for a spatial map of the flux to be developed, enabling real-time analysis of core burnup, power peaking, and rod shadowing. Small diameter thermocouples can be included with the array to also measure the temperature at each location. The following document details the research and development of MPFDs for long term use in nuclear power reactors. Previous MPFD designs were improved, miniaturized, and optimized for long term operations in reactor test ports designed for passive measurements of fluence using iron wires. Detector chambers with dimensions of 0.08 in x 0.06 in x 0.04 in were attached to a common cathode and individual anodes to construct an array of the MPFDs. Each array was tested at the Kansas State University TRIGA Mark II nuclear reactor to demonstrate functionality. The linear response in reactor power was measured. These arrays have also demonstrated reactor power tracking by following reactivity changes in steady state operations and reactor pulsing events. Stability testing showed consistent operation at 100 kW for several hours. The MPFDs have been demonstrated to be a viable technology for in-core measurements.

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Armenta-Durazo, Miguel Alberto 1962. "Experimental determination of the epithermal flux shape-parameter factor, alpha, for the University of Arizona TRIGA Mark I reactor." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276888.

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Assuming an epithermal neutron flux distribution function of the form Φ'epi(E) α 1/E¹⁺ᵅ, the epithermal flux-shape parameter, alpha, and the integrated subcadmium to epicadmium flux ratio, f, were experimentally determined for two irradiation facilities in the University of Arizona TRIGA Mark I reactor. Two equivalent approaches: the Multimonitor method and the Non-linear least-squares method, based on integral (reaction rate) techniques applied to thin foils of gold, zirconium, vanadium, dysprosium, copper, manganese and molybdenum, were used. The Non-linear least-squares approach was found superior to the Multimonitor method on the basis of smaller resulting uncertainties. The resulting parameters are: α = -.0396±.0104 and f = 16.89 ± 1.08 for the Rabbit and α = -.0296 ±.0089 and f = 19.57 ± 1.26 for the Susan, where the reported uncertainties represent one sigma values.

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Murakami, Akira. "Measurement of Neutrino Oscillation Parameters with the Precise Neutrino Flux Prediction in the T2K Experiment." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/175122.

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Sonley, Thomas John. "A measurement of the atmospheric neutrino flux and oscillation parameters at the Sudbury Neutrino Observatory." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/52783.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 119-121).
Through-going muon events are analyzed as a function of their direction of travel through the Sudbury Neutrino Observatory. Based on simulations and previous measurements, muons with a zenith angle of 1 < cos([theta]zenith) < 0:4 are selected as atmospheric neutrino-induced muons. A two-neutrino analysis of these events agrees with the oscillation parameters observed by the Super Kamiokande and Minos experiments, and places 2-D limits of [delta]m2 23 = 1:8+7:1 ??1:1 103 eV2 at the 68% confidence level, and sin2(2[theta]23) > 0:33 at the 90% confidence level. In addition, the flux of atmospheric neutrinos is measured in 1-D with a 68% confidence level to be 1:24+0:11 0:10 times the prediction of the BARTOL group based on SNO data alone, and 1:27+/-0.09 times the prediction when the oscillation parameters are constrained by the Super Kamiokande and Minos results.
by Thomas John Sonley.
Ph.D.

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19

Zirnstein, Eric J. "Simulating hydrogen energetic neutral atom flux measurements for NASA's IBEX mission." Thesis, The University of Alabama in Huntsville, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3631388.

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The heliosphere is a “comet-like” bubble of plasma reaching from ∼10² to over 10³ astronomical units in size. It is created by the outflow of solar wind (SW) plasma and its interaction with the partially-ionized local interstellar medium (LISM). Due to its large size, it is unfeasible to take in situ measurements at the edges of this interaction. Therefore it is necessary to develop sensing techniques to remotely probe the heliosphere and its boundaries.

The NASA-funded Interstellar Boundary EXplorer (IBEX) mission is aimed at improving our understanding of the heliospheric interface. Launched in 2008 October, IBEX measures fluxes of energetic neutral atoms (ENAs) that are created through the SW–LISM interaction, as well as interstellar neutral atoms that permeate the heliospheric boundary. Out of the neutral atom species that IBEX can detect, hydrogen (H) atoms are the most abundant in interstellar space and the heliosphere. Hydrogen ENAs, in particular, are created when relatively energetic protons from the heliospheric plasma charge-exchange with interstellar H atoms. Due to their high energies, and thus large mean free paths, H ENAs can propagate large distances before ionizing (i.e., on the order of the size of the heliosphere), and can be detected by IBEX.

The purpose of this study is to simulate H ENA flux measurements at 1 AU and relate these to the IBEX mission. Three goals of this study that are of particular interest to IBEX are: (1) to simulate H ENA fluxes measured in the solar (inertial) and IBEX spacecraft frames of reference in order to better understand IBEX measurements made in different frames of reference; (2) to study the effects of pickup ions, i.e., non-thermalized ions, on H ENA fluxes, and determine how IBEX observations can reveal the properties of PUIs in the distant heliosphere; (3) to analyze the effects of a time-dependent solar cycle on IBEX H ENA measurements, particularly the “ribbon” of enhanced flux encircling the sky. The simulations are performed by post-processing a pre-simulated, “background” heliosphere containing plasma and neutral H properties (e.g., density, temperature, velocity) produced from a three-dimensional magnetohydrodynamic/kinetic simulation of the SW–LISM interaction.

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Manecki, Szymon M. "Annual Modulation Measurement of the Low Energy Solar Neutrino Flux with the Borexino Detector." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23250.

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This work reports a first attempt to measure the solar neutrino annual
flux modulation due to Earth\'s elliptical orbit with the Borexino detector. Borexino is a real-time calorimetric detector for low energy neutrino spectroscopy located in the underground laboratory of Gran Sasso, Italy. The experiment\'s main focus is the direct measurement of the 7Be solar neutrino flux of all flavors via neutrino-electron scattering in an ultra-pure scintillation liquid. The original goal of this work was to quantify sensitivity of the Borexino detector to a 7% peak-to-peak signal variation over the course of a year and study background stability. A Monte-Carlo simulated sample of the expected variation was prepared in two phases of data acquisition, Phase I that spans from May-2007 to May-2010 and Phase II from October-2011 to September-2012. The data was then fitted in the time domain with a sinusoidal function and analyzed with the Lomb-Scargle fast Fourier transformation in the search for significant periodicities between periods of 0.5 and 1.5 years. The search was performed in the energy window dominated by 7Be, [210; 760] keV, and 60-day bins in the case of the fit and 10-bins for the Lomb-Scargle scan. This work also contains study of the post-purification data of Phase II beyond September-2012 with a prediction for the future sensitivity and justification of the achieved background levels.
Ph. D.

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Loach, James Chilton. "Measurement of the Flux of 8B Solar Neutrinos at the Sudbury Neutrino Observatory." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490107.

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The Sudbury Neutrino Observatory (SNO) was a heavy water Cerenkov detector that had the unique ability to measure both the total il active flux of solar neutrino, using a neutral current (NC) interaction, and the flux of electron neutrinos, using a charged current (CC) interaction. The experiment has demonstrated that neutrinos 3 change flavour and that the total neutrino flux is consistent with the prediction of solar models.

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Wells, C. "The derivation of radiation flux parameters from thermoluminescent dosimetry measurements in mixed neutron/gamma ray fields." Thesis, University of Greenwich, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376564.

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Favorite, Jeffrey Alan. "Variational methods applied to nuclear reactor space-time neutronics." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/16670.

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Güver, Tolga, Feryal Özel, Herman Marshall, Dimitrios Psaltis, Matteo Guainazzi, and Maria Díaz-Trigo. "SYSTEMATIC UNCERTAINTIES IN THE SPECTROSCOPIC MEASUREMENTS OF NEUTRON STAR MASSES AND RADII FROM THERMONUCLEAR X-RAY BURSTS. III. ABSOLUTE FLUX CALIBRATION." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621974.

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Many techniques for measuring neutron star radii rely on absolute flux measurements in the X-rays. As a result, one of the fundamental uncertainties in these spectroscopic measurements arises from the absolute flux calibrations of the detectors being used. Using the stable X-ray burster, GS 1826-238, and its simultaneous observations by Chandra HETG/ACIS-S and RXTE/PCA as well as by XMM-Newton EPIC-pn and RXTE/PCA, we quantify the degree of uncertainty in the flux calibration by assessing the differences between the measured fluxes during bursts. We find that the RXTE/PCA and the Chandra gratings measurements agree with each other within their formal uncertainties, increasing our confidence in these flux measurements. In contrast, XMM-Newton EPIC-pn measures 14.0 +/- 0.3% less flux than the RXTE/PCA. This is consistent with the previously reported discrepancy with the flux measurements of EPIC-pn, compared with EPIC MOS1, MOS2, and ACIS-S detectors. We also show that any intrinsic time-dependent systematic uncertainty that may exist in the calibration of the satellites has already been implicity taken into account in the neutron star radius measurements.

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Wickremasinghe, Don Athula A. "HARP Targets Pion Production Cross Section and Yield Measurements: Implications for MiniBooNE Neutrino Flux." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439295324.

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Shiomi, Koji. "Measurement of K0L flux at the J-PARC neutral-kaon beam line for the K0L → π0νν experiment." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157765.

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Niederhausen, Hans. "Measurement of the High Energy Astrophysical Neutrino Flux Using Electron and Tau Neutrinos Observed in Four Years of IceCube Data." Thesis, State University of New York at Stony Brook, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10823307.

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The high-energy universe is known to be violent. Ultra High Energy Cosmic Rays (UHECRs) have been observed with kinetic energies exceeding 10²⁰ eV. Their origin, despite decades of observations, remains elusive. A unique probe of the sources and production mechanisms of these high energy cosmic rays can be neutrinos, since they are inevitably produced when high-energy protons interact. The IceCube Neutrino Observatory, located at the geographical South Pole in Antarctica, continuously monitors a total volume of 1 km³ of clear Antarctic ice for neutrino interactions. For this purpose, a total of 5160 optical sensors (photomultiplier tubes) have been melted deep into the glacier at depths between 1450m and 2450m. In 2013 IceCube reported one of its biggest discoveries, the observation of highly energetic neutrinos that are consistent with a possible extra-galactic origin.

In this dissertation we use IceCube data (recorded from 2012 to 2015) to study the spectral properties of this astrophysical neutrino flux with focus on electron and tau neutrino flavors. We developed a new neutrino identification and muon background rejection method using state-of-the-art machine-learning techniques, more specifically multi-class gradient boosted decision trees. In addition to enlarging the number of detected neutrino events (>10x increase over previous works), we lowered the energy threshold to below 1 TeV and thereby greatly improved upon the control and treatment of systematic uncertainties. The sample contains ~400 astrophysical electron and tau neutrinos, which increases the significance of the original discovery to beyond 8 standard deviations. We find the astrophysical neutrino flux to be well described by a single power-law consistent with expectations from Fermi-type acceleration of high-energy particles at astrophysical sources and obtain leading constraints on its properties. We further studied the possibility of additional spectral complexity, which significantly increases measurement uncertainties. No evidence for such scenarios was found. Finally we searched for a contribution from atmospheric neutrinos related to heavy meson (charm) decay in Earth's atmosphere and derive a flux upper limit of 4.8 times the benchmark pQCD flux prediction at 90% confidence level, dominated by systematic uncertainties, especially related to photon transport in the glacial ice.

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Blaszczyk, Flor de Maria. "T2K off-axis near detector muon neutrino flux measurement and absolute momentum scale calibration of the off-axis near detector tracker." Paris 7, 2011. http://www.theses.fr/2011PA077157.

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Dans cette thèse les résultats de la mesure du spectre en énergie des neutrino muoniques auprès du détecteur proche hors-axe de T2K et la calibration de l'échelle en impulsion absolue du trajectographe du détecteur proche sont présentés. Nous rappelons d'abord l'histoire et l'état des connaissances actuelles sur la physique du neutrino. Nous donnons aussi le cadre théorique requis à la compréhension des analyses présentées, en particulier le paramétrage des oscillations de neutrino et les modèles d'interaction neutrino-matière. Nous présentons ensuite T2K, une expérience hors-axe à longue ligne de base au Japon, qui envoie un faisceau de neutrinos muoniques depuis J-PARC vers Super-Kamiokande, avec un détecteur proche situé à 280m du site de production des neutrinos. Les objectifs principaux sont la mesure de l'angle thetalB et la mesure précise des paramètres dits atmosphériques. Nous décrivons les différents détecteurs, en particulier le trajectographe du détecteur proche et ses performances. Les outils requis pour les analyses, comme les techniques de reconstruction et de sélection de l'échantillon d'interactions courant chargé pour effectuer la mesure des flux énergétiques, sont expliqués. L'objectif principal de cette thèse, la mesure du spectre énergétique des neutrinos muoniques, est ensuite détaillé, en présentant les motivations de la mesure, les résultats obtenus avec le premier échantillon de données de T2K et les différentes erreurs systématiques étudiées. Finalement, nous présentons la calibration de l'échelle en impulsion absolue du trajectographe du détecteur proche obtenue par la reconstruction de la masse invariante des kaons neutres
In this thesis we present the results from the muon neutrino energy spectrum measurement at T2K's near detecter and T2K's near detecter tracker absolute momentum scale calibration. First we review the main historical steps and the current state of the art of neutrino physics as well as the theoretical framework required to understand the thesis physics analyses presented later on. In particular we focus on the neutrino oscillation parametrization and the neutrino-matter interaction models. We then describe T2K, an off-axis long baseline neutrino oscillation experiment in Japan which uses a muon neutrino beam sent from J-PARC to Super-Kamiokande, with a magnetized near detector located at 280m from the neutrino production site. T2K's main goals are measuring the last unknown angle of the PMNS matrix theta 13 through electron neutrino appearance in the neutrino muon beam and measuring precisely the atmospheric parameters through muon neutrino disappearance. We briefly describe the detectors, in particular the near detector tracker and its performance. We then present the analyses tools, such as the reconstruction techniques used and how the neutrino charged current interaction events needed for the energy spectrum measurement are selected. The main goal of the thesis, the muon neutrino energy spectrum measurement done with the first T2K data is explained next. We give the motivations for such measurement, the results obtained with the first T2K data sample, and the different systematic errors studied. Finally, the absolute momentum scale calibration of T2K's near detector tractor, done through the reconstruction of the neutral kaon invariant mass, is explained

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Pavin, Matej. "Measurements of hadron yields from the T2K replica target in the NA61/SHINE experiment for neutrino flux prediction in T2K." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066573/document.

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T2K est une expérience de neutrinos à longue ligne de base à base d'accélérateurs au Japon. Le but principal de l'expérience T2K est la recherche d'une violation de la PC dans le secteur du lepton en mesurant l'apparence (anti)neutrino des électrons dans un faisceau muon (anti)neutrino. Le flux (anti) neutrino initial est produit par les désintégrations des hadrons qui proviennent des interactions et des ré-interactions d'un faisceau de protons de 30 GeV avec une cible en graphite de 90 cm de long. La connaissance du flux de neutrinos T2K est limitée en raison des grandes incertitudes liées à la production de hadrons. Une série de mesures de production d'hadrons a été effectuée pour résoudre ce problème, dans l'expérience NA61/SHINE au CERN. Les mesures ont été effectuées avec un faisceau de protons et deux types de cibles : une cible en graphite mince et une réplique de la cible T2K. Les travaux présentés dans cette thèse se concentrent sur les données cibles de la réplique T2K prises en 2010 et sur le développement du logiciel d'analyse et d'étalonnage. Le but de ces mesures est de contraindre complètement la production de π+, π+, π-, K+, K+, K- et p provenant de la surface cible en mesurant les rendements différentiels en hadrons dans les cellules du momentum de particules sortant (p), l'angle polaire (θ) et la position longitudinale sur la surface cible (z). Cela permettra de réduire les incertitudes du flux de neutrinos T2K d'environ 10 % à moins de 5 %. Les prédictions de Fluka2011.2c.5 Les listes de physique Monte Carlo, NuBeam et QGSP_BERT de Geant4.10.03 ont été comparées aux données et il a été constaté que Fluka2011.c2.5 donne la meilleure prévision
T2K is an accelerator-based long-baseline neutrino experiment in Japan. The main goal of the T2K experiment is a search for CP violation in the lepton sector by measuring electron (anti) neutrino appearance in a muon (anti)neutrino beam. Initial (anti) neutrino flux is produced in decays of hadrons which originate from the interactions and the re-interactions of a 30 GeV proton beam with a 90 cm long graphite target. Knowledge of the T2K neutrino flux is limited due to large hadron production uncertainties. A series of hadron production measurements were done to solve this problem, in the NA61/SHINE experiment at CERN. Measurements were performed with a proton beam and two target types: a thin graphite target and a replica of the T2K target. Work presented in this thesis concentrates on the T2K replica target data taken in 2010 and the development of the analysis and calibration software. The aim of these measurements is to fully constrain production of π+ , π− , K+ , K− and p coming from the target surface by measuring differential hadron yields in the bins of outgoing particle momentum (p), polar angle (θ) and longitudinal position on the target surface (z). This will allow reduction of the T2K neutrino flux uncertainties from around 10% to below 5%. Predictions of Fluka2011.2c.5 Monte Carlo, NuBeam and QGSP_BERT physics lists from Geant4.10.03 have been compared to the data and it has been found that Fluka2011.c2.5 gives the best prediction

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Mohrmann, Lars [Verfasser], Marek [Akademischer Betreuer] Kowalski, Klas [Akademischer Betreuer] Hultqvist, and Alexander [Akademischer Betreuer] Kappes. "Characterizing cosmic neutrino sources : a measurement of the energy spectrum and flavor composition of the cosmic neutrino flux observed with the IceCube Neutrino Observatory / Lars Mohrmann. Gutachter: Marek Kowalski ; Klas Hultqvist ; Alexander Kappes." Berlin : Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://d-nb.info/1080229566/34.

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McCauley, Neil K. "Producing a background free data set for measurement of the charge current flux and day-night asymmetry at the Sudbury Neutrino Observatory." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270284.

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Ohmes, Martin Francis. "Deployment of a three-dimensional array of micro-pocket fission detector triads (MPFD[superscript]3) for real-time, in-core neutron flux measurements in the Kansas State University TRIGA Mark-II Nuclear Reactor." Diss., Kansas State University, 2012. http://hdl.handle.net/2097/13672.

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Doctor of Philosophy
Department of Mechanical and Nuclear Engineering
Douglas S. McGregor
A Micro-Pocket Fission Detector (MPFD) is a miniaturized type of fission chamber developed for use inside a nuclear reactor. Their unique design allows them to be located between or even inside fuel pins while being built from materials which give them an operational lifetime comparable to or exceeding the life of the fuel. While other types of neutron detectors have been made for use inside a nuclear reactor, the MPFD is the first neutron detector which can survive sustained use inside a nuclear reactor while providing a real-time measurement of the neutron flux. This dissertation covers the deployment of MPFDs as a large three-dimensional array inside the Kansas State University TRIGA Mark-II Nuclear Reactor for real-time neutron flux measurements. This entails advancements in the design, construction, and packaging of the Micro-Pocket Fission Detector Triads with incorporated Thermocouple, or MPFD[superscript]3-T. Specialized electronics and software also had to be designed and built in order to make a functional system capable of collecting real-time data from up to 60 MPFD[superscript]3-Ts, or 180 individual MPFDs and 60 thermocouples. Design of the electronics required the development of detailed simulations and analysis for determining the theoretical response of the detectors and determination of their size. The results of this research shows that MPFDs can operate for extended times inside a nuclear reactor and can be utilized toward the use as distributed neutron detector arrays for advanced reactor control systems and power mapping. These functions are critical for continued gains in efficiency of nuclear power reactors while also improving safety through relatively inexpensive redundancy.

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Ruhe, Tim [Verfasser], Wolfgang [Akademischer Betreuer] Rhode, and Claus [Gutachter] Gößling. "Data mining on the rocks : A measurement of the atmospheric muon neutrino flux using IceCube in the 59-string configuration and a novel data mining based approach to unfolding / Tim Ruhe. Betreuer: Wolfgang Rhode. Gutachter: Claus Gößling." Dortmund : Universitätsbibliothek Dortmund, 2013. http://d-nb.info/1106257421/34.

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Negoita, Cezar Ciprian [Verfasser]. "Measurement of neutron flux spectra in a Tungsten Benchmark by neutron foil activation method / vorgelegt von Cezar Ciprian Negoita." 2004. http://d-nb.info/97240600X/34.

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Dissertations / Theses on the topic 'Neutron flux measurement'

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