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Gamma spectroscopy of the doubly - odd ¹��T1 nucleus.Ramashidzha, Tshifhiwa Marius January 2006 (has links)
<p>The odd &ndash / odd Tl nuclei with A &ge / 190 have moderate oblate nuclear deformation and show rotational bands built on different quasiparticle excitations. Several phenomena, not yet fully understood, were observed in these nuclei, such as large signature splitting in the yrast band (built on a &pi / h9/2&otimes / &nu / i13/2 configuration), possible non &ndash / axiality of the nuclear shape, etc. In this work the high &ndash / spin states in 194Tl were studied. The 194Tl nuclei were produced in the 181Ta (18O, 5n) 194Tl reaction at a beam energy of 93 MeV and the &gamma / - rays were detected using the AFRODITE array. The obtained extended level scheme of 194Tl is presented and discussed in this work. CSM (Cranking shell model) and TRS (Total Routhians Surface) models were both applied to interpret the results for band 1. The results were compared with the neighboring isotone 193Hg.</p>
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Gamma spectroscopy of the doubly - odd ¹��T1 nucleus.Ramashidzha, Tshifhiwa Marius January 2006 (has links)
<p>The odd &ndash / odd Tl nuclei with A &ge / 190 have moderate oblate nuclear deformation and show rotational bands built on different quasiparticle excitations. Several phenomena, not yet fully understood, were observed in these nuclei, such as large signature splitting in the yrast band (built on a &pi / h9/2&otimes / &nu / i13/2 configuration), possible non &ndash / axiality of the nuclear shape, etc. In this work the high &ndash / spin states in 194Tl were studied. The 194Tl nuclei were produced in the 181Ta (18O, 5n) 194Tl reaction at a beam energy of 93 MeV and the &gamma / - rays were detected using the AFRODITE array. The obtained extended level scheme of 194Tl is presented and discussed in this work. CSM (Cranking shell model) and TRS (Total Routhians Surface) models were both applied to interpret the results for band 1. The results were compared with the neighboring isotone 193Hg.</p>
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Use of BC-523a liquid scintillator for simultaneous neutron spectroscopy and gamma counting with the implementation of a neutron history reconstruction algorithm /Frey, Wesley D. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 86-90). Also available on the World Wide Web.
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Gamma spectroscopy of the doubly– ODD 194Tl NucleusRamashidzha, Tshifhiwa Marius January 2006 (has links)
Magister Scientiae - MSc / The odd – odd Tl nuclei with A ≥ 190 have moderate oblate nuclear deformation and show rotational bands built on different quasiparticle excitations. Several phenomena, not yet fully understood, were observed in these nuclei, such as large signature splitting in the yrast band (built on a πh9/2⊗νi13/2 configuration), possible non – axiality of the nuclear shape, etc. In this work the high – spin states in 194Tl were studied. The 194Tl nuclei were produced in the 181Ta (18O, 5n) 194Tl reaction at a beam energy of 93 MeV and the γ - rays were detected using the AFRODITE array. The obtained extended level scheme of 194Tl is presented and discussed in this work. CSM (Cranking shell model) and TRS (Total Routhians Surface) models were both applied to interpret the results for band 1. The results were compared with the neighboring
isotone 193Hg. / South Africa
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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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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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