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Monte Carlo model of a capture gamma ray analyzer for a seafloor core sampleAlmasoumi, Abdullah Muhammad Sultan 06 December 1989 (has links)
Of great benefit, but not limited to seafloor mineral
exploration, is a technique that fairly rapidly determines the
composition of a drilled vibracore (in a time comparable to the time
involved in obtaining the core). The rapid assessment is desired to
predict whether a given region warrants further exploration by
coring.
A proposed monitoring system, based on neutron capture gamma
ray analysis, consists of a container tank filled with water and
tubular extensions that house a Cf-252 neutron source and a
detector positioned within the tank. The core sample is passed
through the system in stop and count steps. The net count rates, due
to "signature" capture gamma rays from neutron capture in elements
in the core sample, are proportional to the amount of the element
responsible for emitting the capture gamma ray.
The proposed system was modeled and simulated by the Monte Carlo
method to predict the relationship between the response of the
detector and the elemental concentrations within the sample.
Accurate and detailed treatment of neutron transport and gamma ray
production and attenuation within the system were employed not only
to predict the relationship of the photopeak responses with respect
to elemental concentrations, but also to permit investigation of the
design parameters and structural material changes in the system.
The developed Monte Carlo code utilizes a variety of variance
reduction techniques, such as implicit absorption with Russian
Roulette and deterministic production of the gamma rays of interest,
along with a form of correlated sampling to predict simultaneously
the responses over a range of interest of the elemental
concentrations. The predicted results were compared with predictions
obtained from a well established general purpose Monte Carlo code
(MCNP). / Graduation date: 1990
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¹⁴C(n,γ) ¹⁵C as a Test Case in the Evaluation of a New Method to Determine Spectroscopic Factors Using Asymptotic Normalization CoefficientsMcCleskey, Matthew Edgar 2011 December 1900 (has links)
With new radioactive isotope accelerators coming online in the next decade, the problem of extracting reliable nuclear structure information from reactions with unstable nuclei deserves considerable attention. A method has been proposed to determine spectroscopic factors (SFs) using the asymptotic normalization coefficient (ANC) to fix the external contribution of a nonperipheral reaction, reducing the uncertainty in the SF. The ¹⁵C[left right arrow]¹⁴C+n system was chosen as a test case for this new method. The direct neutron capture rate on ¹⁴C is important for a variety of topics of interest in astrophysics, and the ANC for ¹⁵C[left right arrow]¹⁴C+n was also used to calculate this reaction rate. The objective of the first part of this work was to find the ANC for ¹⁵C[left right arrow]¹⁴C+n. This was done in two independent experiments. First, the heavy ion neutron transfer reaction ¹³C(¹⁴C,¹⁵C)¹²C was measured at 12 MeV/nucleon. Second, the inverse kinematics reaction d(¹⁴C,p)¹⁵C was measured using the new Texas Edinburgh Catania Silicon Array (TECSA). The next phase of the experimental program was to measure a reaction with a non-negligible interior contribution, for which ¹⁴C(d,p)¹⁵C at 60 MeV deuteron energy was used. This reaction turned out to be more peripheral than anticipated, and as a result, the ANC for the ground state was extracted from this measurement as well. The final results for the three measurements are C²2s1/2 = 1.96±0.16 fm⁻¹ for the ground state and C²1d5/2 = (4.23±0.38)·10⁻³ fm⁻¹ for the first excited state. Because the 60 MeV ¹⁴C(d,p)¹⁵C reaction turned out to have a very weak dependence on the interior, the SF could not be determined for the ¹⁴C+n ground state in ¹⁵C using the new method. A lower limit of 1.05 was found for the first excited state. It is possible that other reactions might turn out to be more suitable for this method, however, the difficulty encountered at this relatively high deuteron energy highlights a substantial problem likely to be seen in other applications. Using the ANCs determined in this work, the astrophysical ¹⁴C(n,γ)¹⁵C reaction rate was calculated. The resulting value for the cross section for capture to the ground state at 23 keV was σgs(23 keV)=5.1±0.4 μb and to the first excited state was σexc(23 keV)=0.2±0.02 μb.
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Monte Carlo design and simulation of a shipboard ²⁵²Cf-based PGNAA analyzer for the sensitivity analysis of seafloor coresAnand, Ajay, 1961- 14 May 1991 (has links)
The seabed is envisaged to meet the increased future demands for
minerals from the rapidly growing industrialized societies of the world.
Shipboard analysis of cores can significantly reduce the cost and time
spent at the exploratory drilling stage by obviating the need to go back
to land for analysis. It can further speed the exploration process by
enabling a quick modification of the exploration plan based on the
results of the shipboard analysis.
A ²⁵²Cf-based analyzer utilizing the prompt gamma neutron
activation analysis technique has been designed. The analyzer is a
spherical iron shell with the source at its center. The seabed core is
passed through a hollow composite tube which is positioned a short
distance directly below the source and the resulting prompt gamma rays
are collimated to a HPGe detector. The rest of the sphere is filled
with paraffin. The gamma ray flux at the detector is converted into a
count rate by using a semi-empirical detector response function. This
count rate data are then used to determine the sensitivity and detection
limits for the chosen elements (Mg, Al, Ti, Cr, Mn, Fe, Ni and Cu).
Monte Carlo simulations using the Monte Carlo neutron photon
coupled transport code, MCNP, were carried out for a parametric study of
important variables influencing the design of the analyzer. These
parameters included the moderator type, source to sample distance and
sample porosity. MCNP was then used to model the analyzer and to
generate the neutron flux profiles in the sample and the prompt gamma
flux at the detector.
Due to the non-availability of the prompt gamma data for most of
the elements of economic interest in the ENDF/B-V cross section
libraries associated with MCNP, the point kernel photon transport code
ISOSHLD-II (modified for high energy gamma rays) was used to generate
the gamma flux at the detector for specific elements. The ISOSHLD-II
source term was calculated based on known gamma production data (thermal
capture only) and the thermal neutron flux in the sample obtained from
MCNP computations.
The sensitivity and detection limits obtained from the isotopic
source based analyzer were compared for the case of aluminum with values
reported from reactor facilities.
The results obtained indicate that the analyzer designed in this
work could prove suitable for the on-line analysis of many elements of
economic interest in seabed cores at the 1 weight percent level. / Graduation date: 1992
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Optimized accelerator based epithermal neutron beams for boron neutron capture therapy /Kudchadker, Rajat, January 1996 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 146-151). Also available on the Internet.
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Optimized accelerator based epithermal neutron beams for boron neutron capture therapyKudchadker, Rajat, January 1996 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 146-151). Also available on the Internet.
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Targeting CD37 and folate receptor for cancer therapy strategies based on engineered protein and liposomes /Zhao, Xiaobin. January 2007 (has links)
Thesis (Ph. D.)--Ohio State University, 2007. / Full text release at OhioLINK's ETD Center delayed at author's request
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PARITY VIOLATION IN THE HADRONIC WEAK INTERACTIONJanuary 2012 (has links)
abstract: This thesis deals with the first measurements done with a cold neutron beam at the Spallation Neutron Source at Oak Ridge National Laboratory. The experimental technique consisted of capturing polarized cold neutrons by nuclei to measure parity-violation in the angular distribution of the gamma rays following neutron capture. The measurements presented here for the nuclei Chlorine ( 35Cl) and Aluminum ( 27Al ) are part of a program with the ultimate goal of measuring the asymmetry in the angular distribution of gamma rays emitted in the capture of neutrons on protons, with a precision better than 10-8, in order to extract the weak hadronic coupling constant due to pion exchange interaction with isospin change equal with one ( hπ 1). Based on theoretical calculations asymmetry in the angular distribution of the gamma rays from neutron capture on protons has an estimated size of 5·10-8. This implies that the Al parity violation asymmetry and its uncertainty have to be known with a precision smaller than 4·10-8. The proton target is liquid Hydrogen (H2) contained in an Aluminum vessel. Results are presented for parity violation and parity-conserving asymmetries in Chlorine and Aluminum. The systematic and statistical uncertainties in the calculation of the parity-violating and parity-conserving asymmetries are discussed. / Dissertation/Thesis / Ph.D. Physics 2012
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Avaliacao dosimetrica da solucao fricke gel usando a tecnica de espectrofotometria para aplicacao na dosimetria de eletrons e neutrons / Dosimetric evaluation of the fricke gel dosimeter using the spectrophotometric technique for application in electron and neutron dosimetryMANGUEIRA, THYAGO F. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:26:53Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:05Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Caracterização do campo de nêutrons na instalação para estudo e, BNCT no reator IEA-R1 / Neutron field characterization in the installation for BNCT study in the IEA-R1 reactorCARNEIRO JUNIOR, VALDECI 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:54:33Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:52Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN/CNEN-SP
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Avaliacao dosimetrica da solucao fricke gel usando a tecnica de espectrofotometria para aplicacao na dosimetria de eletrons e neutrons / Dosimetric evaluation of the fricke gel dosimeter using the spectrophotometric technique for application in electron and neutron dosimetryMANGUEIRA, THYAGO F. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:26:53Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:05Z (GMT). No. of bitstreams: 0 / Neste trabalho as principais características dosímetricas da solução Fricke Xilenol Gel (FXG) foram estabelecidas para futura aplicação clínica na dosimetria de elétrons. As curvas de dose resposta para feixes de nêutrons térmicos para pesquisa em Terapia por Captura de Nêutrons (BNCT) e feixes elétrons de aplicação industrial também foram determinadas. A técnica padrão de leitura utilizada foi espectrofotometria. Para o feixe clínico as reprodutibilidades intra e inter-lotes da solução FXG são melhores que 1,4 % e 5,1 % respectivamente, o comportamento da resposta para o intervalo de dose entre 0,2 e 40 Gy é linear e independente da energia e da taxa de dose para o intervalo estudado. Devido aos efeitos da oxidação natural do FXG o tempo ótimo entre o preparo e a irradiação é de 24h e o comportamento da curva de dose resposta não se altera no período estudado para a variação da absorvância líquida do dosímetro. Para o estudo com o campo de nêutrons as curvas de dose resposta do FXG apresentaram comportamento linear em todo intervalo de dose estudado, e para campos industriais de elétrons o comportamento é exponencial decrescente. De acordo com os resultados obtidos para os feixes de radiação estudados, não houve alteração na posição das bandas características do espectro de absorção do FXG. Como testes adicionais, foi determinada a viabilidade do uso do método de leitura do FXG por imagens fotográficas digitais e aplicação do FXG na dosimetria para braquiterapia intracavitária. O bom desempenho do dosímetro FXG nos testes realizados indica que este pode ser utilizado na avaliação tridimensional da dose em tratamento radioterápicos. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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