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1
Przibislawsky, Csilla. "Authentic neutral mask : a new method of drama therapy." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ47878.pdf.
Testo completo
2
Cui, Jun. "Analysis of Titan's Neutral Upper Atmosphere from Cassini Ion Neutral Mass Spectrometer Measurements in the Closed Source Neutral Mode." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/195580.
Testo completoAbstract (sommario):
In this thesis I present an in-depth study of the distribution of various neutral species in Titan’s upper atmosphere, at altitudes between 950 and 1,500 km for abundant species (N₂, CH₄ as well as their isotopes) and between 950 and 1,200 km for most minor species. However, the study of the H2 distribution on Titan is extended to an altitude as high as 6,000 km in the exosphere. The analysis is based on a large sample of Cassini/INMS (Ion Neutral Mass Spectrometer) measurements in the CSN (Closed Source Neutral) mode, obtained during 15 close flybys of Titan. The densities of abundant species including N₂, CH₄ and H₂ are determined directly from their main channels. However, to untangle the overlapping cracking patterns of minor species, the technique of Singular Value Decomposition (SVD) is used to determine simultaneously the densities of various hydrocarbons, nitriles and oxygen compounds. All minor species except for ⁴⁰Ar present density enhancements measured during the outbound legs. This can be interpreted as a result of wall effects, which could be either adsorption/desorption or heterogeneous surface chemistry on the chamber walls. In the thesis, I use a simple model to describe the observed time behavior of minor species. Results on their atmospheric abundances are provided both in terms of direct inbound measurements assuming ram pressure enhancement and values corrected for wall adsorption/desorption. Among all minor species of photochemical interest, the INMS data provide direct observational evidences for C₂H₂, C₂H₄, C₂H₆, CH₃C₂H, C₄H₂, C₆H₆, HC₃N and C₂N₂ in Titan’s upper atmosphere. Upper limits are put for other minor species. The globally averaged distribution of N₂, CH₄ and H₂ are each modeled with the diffusion approximation. The N₂ profile suggests an average thermospheric temperature of 154 K. The CH₄ and H₂ distribution constrains their fluxes to be 3.0×10⁹ cm⁻² s⁻¹ and 1.3×10¹⁰ cm⁻² s⁻¹, referred to Titan’s surface. The H₂ escape flux is about a factor of ∼3 higher than the Jeans value, which is interpreted as enhanced thermal escape driven primarily by an upward conductive heat flux. Such a conclusion is based on kinetic model calculations in the 13-moment approximation that require energy continuity at the upper boundary. On the other hand, a proper interpretation of the observed CH4 escape has to rely on the detailed nonthermal processes, which are still unknown at the present time. The INMS observations of the nitrogen isotope ratio implies ¹⁴N/¹⁵N= 131.6 near Titan’s surface. The profile of carbon isotope ratio combining INMS and GCMS results implies that both CH₄ and its isotope escape from Titan’s exobase with roughly the same drift velocity, in contrast to the Jeans case which requires that CH₄ escapes with a much larger velocity due to its smaller mass. The INMS data also suggest horizontal/diurnal variations of temperature and neutral gas distribution in Titan’s thermosphere. The equatorial regions, the ramside, as well as the nightside hemisphere of Titan appear to be warmer and present some evidences for the depletion of light species such as CH₄. Meridional variations of most heavy species are also observed, with a trend of depletion toward the north pole. Though some of the above variations might be interpreted by either the solardriven models or plasma-driven models, a physical scenario that reconciles all the observed horizontal/diurnal variations in a consistent way is still missing, With a careful evaluation of the effect of restricted sampling, some of the features shown in the INMS data are more likely to be observational biases.
3
Wheeler, Susan F. "Structural determination of complex anionic oligosaccharides by mass spectrometry." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365367.
Testo completo
4
Chen, Xiaohong. "Neutralization-reionization mass spectrometric and computational studies of elusive neutral intermediates /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8643.
Testo completo
5
Nogowski, René. "Precision Measurement of the Mass Difference of Neutral and Charged B Mesons." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1200514656539-83248.
Testo completoAbstract (sommario):
This work presents a precision determination of the mass difference of neutral and charged B mesons, m(B0) - m(B+). The measurement is based on a data sample of about 232 million B-meson pairs recorded with the BABAR detector at the e+e- storage-ring system PEP-II. In events of e+e- --> Upsilon(4S) --> B Bbar, B0 and B+ mesons are fully reconstructed in decays B+ --> J/psi K+ and B0 --> J/psi K*0 using the subsequent decays J/psi --> l+ l- and K*0 --> K+ pi- for the reconstruction of J/psi mesons and K*0 resonances, respectively. The determination of the mass difference from the measurement of the invariant B-meson masses suffers from detector-resolution effects. To reach the desired sensitivity, the B-meson momenta are measured in the center-of-mass system, the Upsilon(4S) rest frame. Since their energy is also known in the center-of-mass system, this method leads to the mass difference using the relativistic energy-momentum relation. For this purpose, three different fit methods are performed to the spectra of the B momenta. The obtained result is m(B0) - m(B+) = (+0.33 +- 0.05 +- 0.03) MeV/c^2, where the first error is statistical and the second estimates the systematic uncertainty of this measurement, which agrees well with the current world average. However, the combined error of this measurement is substantially smaller than that in the current world average, and the significance of m(B0) - m(B+) being non-zero has exceeded the 5 sigma level.
6
Lenkewitz, Mark [Verfasser]. "Neutral Pion Electroproduction off Light Nuclei in Chiral Perturbation Theory / Mark Lenkewitz." Bonn : Universitäts- und Landesbibliothek Bonn, 2013. http://d-nb.info/1045872075/34.
Testo completo
7
Nogowski, René. "Precision Measurement of the Mass Difference of Neutral and Charged B Mesons." Doctoral thesis, Technische Universität Dresden, 2007. https://tud.qucosa.de/id/qucosa%3A23992.
Testo completoAbstract (sommario):
This work presents a precision determination of the mass difference of neutral and charged B mesons, m(B0) - m(B+). The measurement is based on a data sample of about 232 million B-meson pairs recorded with the BABAR detector at the e+e- storage-ring system PEP-II. In events of e+e- --> Upsilon(4S) --> B Bbar, B0 and B+ mesons are fully reconstructed in decays B+ --> J/psi K+ and B0 --> J/psi K*0 using the subsequent decays J/psi --> l+ l- and K*0 --> K+ pi- for the reconstruction of J/psi mesons and K*0 resonances, respectively. The determination of the mass difference from the measurement of the invariant B-meson masses suffers from detector-resolution effects. To reach the desired sensitivity, the B-meson momenta are measured in the center-of-mass system, the Upsilon(4S) rest frame. Since their energy is also known in the center-of-mass system, this method leads to the mass difference using the relativistic energy-momentum relation. For this purpose, three different fit methods are performed to the spectra of the B momenta. The obtained result is m(B0) - m(B+) = (+0.33 +- 0.05 +- 0.03) MeV/c^2, where the first error is statistical and the second estimates the systematic uncertainty of this measurement, which agrees well with the current world average. However, the combined error of this measurement is substantially smaller than that in the current world average, and the significance of m(B0) - m(B+) being non-zero has exceeded the 5 sigma level.
8
Sangaroon, Siriyaporn. "Study of Collimated Neutron Flux Monitors for MAST and MAST Upgrade." Doctoral thesis, Uppsala universitet, Tillämpad kärnfysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-221591.
Testo completoAbstract (sommario):
Measurements of the neutron emission, resulting from nuclear fusion reactions between the hydrogen isotopes deuterium and tritium, can provide a wealth of information on the confinement properties of fusion plasmas and how these are affected by Magneto-Hydro-Dynamic (MHD) instabilities. This thesis describes work aimed to develop neutron measurement techniques for nuclear fusion plasma experiments, specifically regarding the performance and design of collimated neutron flux monitors (neutron cameras) for the Mega Ampere Spherical Tokamak, MAST, and for MAST Upgrade. The first part of the thesis focuses on the characterization of a prototype neutron camera installed at MAST and provides an account of the very first measurements of the neutron emissivity along its collimated fields of view. It is shown that the camera has sufficient temporal and spatial resolution to measure the effect of MHD instabilities on the neutron emissivity. The neutron camera fulfils the requirement on the measurements of the neutron count rate profile with less than 10 % statistical uncertainty in a time resolution of 1 ms. The instrument's more rudimentary capabilities to provide information on the neutron energy distribution are also presented and discussed. The encouraging results obtained with the prototype neutron camera show the potential of a collimated neutron flux monitor at MAST and suggest that an upgraded instrument for MAST Upgrade will provide crucial information on fast ions behavior and other relevant physics issues. The design of such an upgraded instrument for MAST Upgrade is discussed in the second part of the thesis. Two design options are explored, one consisting of two collimator arrays in the horizontal direction, another more traditional design with lines-of-sight in the poloidal cross section plane. On the basis of the experience gained with the prototype neutron camera and on the exploratory design and estimated performance for the upgraded camera presented here, a conceptual design of a neutron camera upgrade is proposed.
9
Woods, P. J. "Mass measurements of light neutron rich nuclei." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374579.
Testo completo
10
Klimek, Iwona. "Modelling and Measurements of MAST Neutron Emission." Doctoral thesis, Uppsala universitet, Tillämpad kärnfysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-282122.
Testo completoAbstract (sommario):
Measurements of neutron emission from a fusion plasma can provide a wealth of information on the underlying temporal, spatial and energy distributions of reacting ions and how they are affected by a wide range of magneto-hydro-dynamic (MHD) instabilities. This thesis focuses on the interpretation of the experimental measurements recorded by neutron flux monitors with and without spectroscopic capabilities installed on the Mega Ampere Spherical Tokamak (MAST). In particular, the temporally and spatially resolved measurements of the neutron rate measured by the neutron camera, which also possesses spectroscopic capabilities, are combined with the temporally resolved measurements of the total neutron rate provided by the absolutely calibrated fission chamber in order to study the properties of the fast ion distributions in different plasma scenarios. The first part of the thesis describes in detail the two forward modelling methods, which employ the set of interconnected codes developed to interpret experimental observations such as neutron count rate profiles and recoil proton pulse height spectra provided by the neutron camera. In the second part of the thesis the developed methods are applied to model the neutron camera observations performed in a variety of plasma scenarios. The first method, which involves only TRANSP/NUBEAM and LINE2 codes, was used to validate the neutron count rate profiles measured by the neutron camera in three different plasma scenarios covering the wide range of total neutron rate typically observed on MAST. In addition, the first framework was applied to model the changes in the total and local neutron rates caused by fishbone instability as well as to estimate the Hydrogen and Deuterium ion ratio. The second modelling method, which involves TRANSP/NUBEAM, LINE2, DRESS and NRESP, was used to validate the measured recoil proton pulse height spectra in a MHD-quiescent plasma scenario.
11
Parry, Christopher Mark. "Spectroscopy of neutron deficient mass A=130 nuclei." Thesis, University of York, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313864.
Testo completo
12
Chen, Hongwen. "Investigations of ionic and neutral species in the gas phase by tandem mass spectrometry." Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/7647.
Testo completoAbstract (sommario):
A major application of tandem mass spectrometry is the study of gas-phase ion chemistry. Gas-phase ion chemistry involving ion thermochemistry and ion dissociation characteristics, is one of the foundations of analytical chemistry. A signal (peak) in a mass spectrum is only identified by its mass-to-charge ratio (m/z) and may represent several isomeric ions. Isomeric species having the same element composition can be distinguished by tandem mass spectrometry. An investigation of isomeric (C,H$\sb3,$N,O) $\sp{+-}$ ions provides such an example, where four isomeric ions ( (H$\sb2$NC(H)O) $\sp{+-}$, (H$\sb2$NCOH) $\sp{+-}$, (H$\sb3$CNO) $\sp{+-}$ and (H$\sb2$CNOH) $\sp{+-}$) and their neutral counterparts were identified by a combination of experimental results and a recent high level ab initio molecular orbital theory calculation. Many elusive neutral species of great interest have been accessed by a tandem mass spectrometric technique, neutralization-reionization mass spectrometry (NRMS), which was developed in the last decade. In this thesis, three oxides of carbon, O=C=C=O, C=C=O and O=C=C=C=O, which have been the object of many studies by experimentalists and theoreticians for almost a century, were first observed as stable neutral species in the gas phase by NRMS. In the gas phase, structures of isomeric species having unique behaviours, such as the two cis and trans isomeric 2-buten-dicarboxylic acids, maleic and fumaric acids, can be defined by full investigations of their molecular ions and major fragment ions. The investigations which involved studies of ion thermochemistry and ion dissociation characteristics as well as the use of isotopically labelled compounds provide more information than an early work which used only conventional mass spectrometric techniques.
13
Bekele, Selemon. "Neutral kaon correlations in Au-Au collisions at center of mass energy of 200 GeV per nucleon pair." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1086177649.
Testo completo
14
Viel, Simon. "Search for new neutral high-mass resonances decaying into muon pairs with the ATLAS detector." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/49948.
Testo completoAbstract (sommario):
The question of physics beyond the Standard Model remains as crucial as it was before the discovery of a Higgs boson at the Large Hadron Collider, as the theoretical and experimental shortcomings of the Standard Model remain unresolved. Indeed, theoretical problems such as the hierarchy of energy scales, the Higgs mass fine-tuning and the large number of postulated parameters need to be addressed, while the experimental observations of dark matter, dark energy and neutrino masses are not explained by the Standard Model. Many hypotheses addressing these issues predict the existence of new neutral high-mass resonances decaying into muon pairs.
This dissertation documents a search for this process using 25.5 inverse femtobarns of proton-proton collision data collected by the ATLAS experiment in Run‑I of the Large Hadron Collider. After evaluating the performance of the detector for reconstructing muons at very high momentum, the event yields observed as a function of the invariant mass of muon pairs are compared with expected values from Standard Model processes.
The observed yields are found to be in good agreement with Standard Model predictions, and no significant excess of events is found. New gauge bosons with couplings to fermions equal to these of the Standard Model Z boson and with masses lower than 2.53 TeV are therefore excluded at 95% confidence level. A statistical combination with the results of the search for the same particle decaying into electron pairs yields a lower mass limit of 2.90 TeV at 95% confidence level. Limits are also placed in the context of two classes of models inspired by Grand Unification Theories: gauge theories with the E₆ symmetry group, as well as Minimal Z' Models.<br>Science, Faculty of<br>Physics and Astronomy, Department of<br>Graduate
15
Savaloni, Hadi. "Elastic scattering of 3.0 MeV polarised neutrons by medium mass nuclei." Thesis, University of Edinburgh, 1985. http://hdl.handle.net/1842/11370.
Testo completo
16
Caamano, Monica. "New isomers in the neutron-rich A~190 mass region." Thesis, University of Surrey, 2002. http://epubs.surrey.ac.uk/844621/.
Testo completoAbstract (sommario):
Previously unobserved isomeric states in 188Ta,190W, 192Re, 193Re, 195Os, 197Ir, 198Ir, 200Pt, 201Pt, 202Pt and 203Au, with half-lives ranging from 10 ns to 290 mus have been populated and studied using a fragmentation reaction in conjunction with a forward focussing spectrometer. In most cases, this provided the first ever spectroscopic data made available for the nucleus, and 200Pt presented the first new seniority 4 state, on the basis of gamma-gamma coincidences, following a fragmentation reaction. Half-lives have been measured and tentative level schemes have been drawn for each isomer, spins and parities being consistent with blocked BCS calculations, hindrance factors, systematics and the relative intensities of gamma-rays and X-rays (where possible). Isomeric ratios have been measured, values ranging from 1 % to 64 %. Potential Energy Surface calculations were performed in parallel to the blocked BCS calculations, in order to provide deformation parameters, excitation energies and quasiparticle configurations. Ground state (or lowest level) shape calculations reveal a change from axially symmetric, through triaxial, to spherical shapes across the data set, from 188Ta to 203Au, as 208Pb approached. Weisskopf hin-drance factors provide evidence for the erosion of the goodness of the K-quantum number, compatible with soft or axially symmetric shapes. The prolate-oblate phase transition region, with respect to tungsten, osmium and platinum, shows 195Os to be the pivotal nucleus in the osmium isotopic chain, with a calculated triaxial ground state. On comparison with the systematics of the region, results obtained for 190W show evidence for a Z = 74 sub-shell closure, analogous to that at Z = 64. Finally, new isotopes, 167Tb, 170Dy and 199Ir were discovered.
17
Krauss, Miriam Ilana. "X-ray spectroscopy of neutron star low-mass X-ray binaries." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/45408.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2007.<br>Includes bibliographical references (p. 133-150).<br>In this thesis, I present work spanning a variety of topics relating to neutron star lowmass X-ray binaries (LMXBs) and utilize spectral information from X-ray observations to further our understanding of these sources. First, I give an overview of important X- ray astrophysics relevant to the work I present in subsequent chapters, as well as information about the X-ray observatories from which I obtained my data. In the next three chapters, I consider spectra-both high- and low-resolution--of accretion-powered millisecond X-ray pulsars, a unique and relatively new class of objects. In addition to analysis of the pulsar XTE J1814-338, I compare a broader sample of pulsars with a sample of atoll sources in order to better understand why the latter class do not contain persistently pulsating neutron stars. In particular, I test the hypothesis that pulsations in the atoll sources are suppressed by a high-optical- depth scattering region. Using X-ray color-color diagrams to define a selection criterion based on spectral state, I analyze Rossi X-ray Timing Explorer (RXTE) spectra from all the sources, and use a Comptonization model to obtain measurements of their optical depths. I then discuss efforts to spatially resolve X-ray jets from the accretion-powered millisecond pulsar SAX J1808.4-3658 and the Z source XTE J1701-462. Each was observed by the Chandra X-ray Observatory to produce a high-spatial-resolution image. This work was motivated in part by my analysis of XTE J1814-338, which found an apparent excess of infrared flux which could be attributed to jet emission. Next, I discuss the measured temperatures of thermonuclear X-ray bursts. The detection of line features in these bursts, and hence from the surfaces of neutron stars, has been an important goal for high-resolution X-ray spectroscopy. A measurement of the wavelengths of identified line features would yield a measurement of the neutron star's gravitational redshift, which would help constrain current models for the neutron star equation of state.<br>(cont.) Although such a measurement has been made for one source, other searches have not been able to repeat this measurement. I consider the effects of burst temperature on the formation of discrete spectral features, using a large sample of bursts observed by the RXTE PCA. Finally, I present analysis of high-resolution Chandra HETG spectra of a sample of Galactic LMXBs. High-resolution spectra are able to resolve line features, such as the prominent Ne and O emission lines in the ultracompact X-ray binary 4U 1626-67. They also allow for more precise measurements of photoelectric absorption edges, which can otherwise hinder the determination of continuum spectral components, particularly in the lower-energy spectral regions.<br>by Miriam Ilana Krauss.<br>Ph.D.
18
Lin, Dacheng. "The accretion process in neutron-star low-mass X-ray binaries." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/62866.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Cataloged from student submitted PDF version of thesis.<br>Includes bibliographical references (p. 207-221).<br>There had been long-standing fundamental problems in the spectral studies of accreting neutron stars (NSs) in low-mass X-ray binaries involving the X-ray spectral decomposition, the relations between subtypes (mainly atoll and Z sources), and the origins of different X- ray states. Atoll sources are less luminous and have both hard and soft spectral states, while Z sources have three distinct branches (horizontal(HB)/normal(NB)/flaring(FB)) whose spectra are mostly soft. I analyzed more than twelve-year RXTE observations (~ 2500 in total) of four atoll sources Aql X-1, 4U 1608-522, 4U 1705-44, and 4U 1636-536. I developed a hybrid spec- tral model for accreting NSs. In this model, atoll hard-state spectra are described by a single-temperature blackbody (BB), presumed to model emission from the boundary layer where the accreted material impacts the NS surface, and a strong Comptonized compo- nent, modeled by a cutoffpl power law (CPL). Atoll soft-state spectra are described by two thermal components, i.e., a multicolor disk (MCD) and a BB, with additional weak Comp- tonized component, modeled by a single power law. I found that the accretion disk in most of the soft state is truncated at a constant value, most probably at the innermost stable circular orbit (ISCO), predicted by general relativity. This allows us to derive upper limits of magnetic fields on the NS surface of the above four atoll sources. The apparent emission area of the boundary layer is small, ~1/16 of the whole NS surface, but is fairly constant, spanning the hard and soft states. All this was not seen if the classical models for thermal emission plus high Comptonization were used instead. By tracking the accretion rate onto the NS surface, I inferred a strong mass jet in the hard state. My study of 4U 1705-44 using broadband spectra from Suzaku and BeppoSAX supported the above results. From my spectral study of the above four atoll sources, I also found that in a part of the soft state with frequent occurrences of kilohertz quasi-periodic oscillations (kHz QPOs), the accretion disk appears to be truncated at larger radii than in other parts of the soft state where the disk is presumably truncated at the ISCO. Thus the production of kHz QPOs in accreting NSs should be closely related to the behavior of the accretion disk. It is well known that the kHz QPO amplitude spectrum tracks the BB, even though we see no changes in the BB spectral evolution track when kHz QPOs are present. The simplest interpretation is that accretion oscillations are imparted in the inner disk and then seen as the waves impact the NS surface in the boundary layer. The transient XTE J1701-462 (2006-2007) is the only source known to exhibit properties of both the Z and atoll types. I carried out the state/branch classifications of all the ~900 RXTE observations. The Z-source branches evolved substantially in the X-ray color-color diagram during this outburst. In the decay, the HB, NB and FB disappeared successively, with the NB/FB transition evolving to the atoll-source soft state. Spectral analyses using my new spectral model show that the inner disk radius maintains at a nearly constant value, presumably at ISCO, when the source behaves as an atoll source in the soft state, but increases with accretion rates when the source behaves as a Z source at high luminosity. We interpreted this as local Eddington limit effects and advection domination in the accretion disk. The disks in the two Z vertices probably represent two stable accretion configurations, and we speculate that the lower (NB/FB) vertex represents a standard thin disk and the upper (HB/NB) vertex a slim disk. The changes in the accretion rate are responsible for movement of Z-source branches and the evolution from one source type to another. However, the three Z-source branches are caused by three mechanisms that operate at a roughly constant accretion rate. The FB is an instability tied to the Eddington limit. It is formed as the inner disk radius temporarily decreases toward the ISCO. The NB is traced out mostly due to changes in the boundary layer emission area, as a result of the system transiting from a standard thin disk to a slim disk. The HB is formed with the increase in Comptonization, consistent with strong radio emission detected from this branch.<br>by Dacheng Lin.<br>Ph.D.
19
Ryan, Garrett. "Maximum Mass Restraint of Neutron Stars: Quarks, Pion, Kaons, and Hyperons." Scholarship @ Claremont, 2017. http://scholarship.claremont.edu/cmc_theses/1535.
Testo completoAbstract (sommario):
This thesis explores the topic of maximum mass stability of neutron stars. The outer structure is detailed and explores nuclear pasta phases, the neutron drip line, and density transitions of matter in the crust and atmosphere layers. Other discussion points include superfluids in the crust and core, vortex roles in neutron stars, and magnetic field effects on the EOS in neutron stars. The inner core is studied in much more detail due to its significant role in EOS. The variety of stars include pion condensate stars, kaon condensate stars, npeu stars, npeu stars with the inclusion of hyperons, quark-hybrid stars, and strange stars. Included with these is a description of nucleon-nucleon, nucleon-nucleon-nucleon interactions, the appearance factors that affect hyperon species, and the formation process of kaons, pions, quarks, and hyperons. The ending EOS are compared with their maximum mass values to determine which ones are likely to limit the mass of neutron stars.
20
Garcia, Krystine. "Bioinformatics Pipeline for Improving Identification of Modified Proteins by Neutral Loss Peak Filtering." Ohio University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1440157843.
Testo completo
21
DeWolf, R. S. "Charged and neutral particle production in proton-antiproton interactions at 200 and 900 GeV centre of mass energies." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481568.
Testo completo
22
Wilson, Roderick Charles. "The design, construction and characterisation of an ion optical system for Sputtered Neutral and Secondary Ion Mass Spectrometry." Thesis, University of Manchester, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334920.
Testo completo
23
Cui, J., Y. T. Cao, P. P. Lavvas, and and T. T. Koskinen. "THE VARIABILITY OF HCN IN TITAN’S UPPER ATMOSPHERE AS IMPLIED BY THE CASSINI ION-NEUTRAL MASS SPECTROMETER MEASUREMENTS." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621401.
Testo completoAbstract (sommario):
HCN is an important constituent in Titan's upper atmosphere, serving as the main coolant in the local energy budget. In this study, we derive the HCN abundance at the altitude range of 960-1400 km, combining the Ion-Neutral Mass Spectrometer data acquired during a large number of Cassini flybys with Titan. Typically, the HCN abundance declines modestly with increasing altitude and flattens to a near constant level above 1200 km. The data reveal a tendency for dayside depletion of HCN, which is clearly visible below 1000 km but weakens with increasing altitude. Despite the absence of convincing anti-correlation between HCN volume mixing ratio and neutral temperature, we argue that the variability in HCN abundance makes an important contribution to the large temperature variability observed in Titan's upper atmosphere.
24
Blom, Erik. "Characterization of γ-rays at MAST". Thesis, Uppsala universitet, Tillämpad kärnfysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388424.
Testo completoAbstract (sommario):
The γ-ray characterizing possibility of the neutron collimated flux monitor (in short, Neutron Camera) at the Mega Ampere Spherical Tokamak (MAST) is explored. Typically used to monitor neutron emission, the Neutron Camera has excellent neutron/γ-ray discrimination properties and thus presents the opportunity to measure spatially and temporally resolved γ-ray emission - a possibility of an additional fusion diagnostics method with already existing equipment. An Online Data Analysis (ODA) code was used to analyze the data on γ-rays from several plasma discharges with similar plasma parameters. A high statistics temporal distribution of the γ-ray emission and a lower statistics spatial distribution were analyzed. However, the low energy resolution and range for the Neutron Camera γ-ray measurements revealed few conclusive results on the origin of the higher energy γ-rays. Detection systems with higher energy resolution and range are suggested for an extensive analysis of γ-ray emission at MAST Upgrade.
25
Al-Garni, Sareh D. "Search for long lived isomers in the neutron-rich mass 180 region." Thesis, University of Surrey, 2002. http://epubs.surrey.ac.uk/843292/.
Testo completoAbstract (sommario):
Nuclei in the A~ 180 region were populated and investigated in a series of deep-inelastic reactions involving an 11.4 MeV per nucleon 136Xe beam produced by the GSI UNILAC accelerator, impinging on a selection of tantalum, tungsten and rhenium targets. The reaction products were released from both thermal (TIS) and FEBIAD ion sources and subsequently mass-separated using the GSI on-line mass separator. This work concentrates on the observation of gamma rays associated with the decay of the well known Kpi= 37/2--, t1/2 = 51.4 min. isomer in 177Hf. Due to the anomalous half-life characteristics and unexpectedly high yield of this decay, it is interpreted as being fed via the beta-decay of a high-K isomer in 177Lu. By comparing the experimental findings with the results obtained from multi-quasiparticle blocked-BCS-Nilsson calculations (which predict a low-lying state with Kpi = 39/2-- in 177Lu), the proposed decay is suggested to be an energetically favoured Kpi= 39/2-- five-quasiparticle state in 177Lu. A half-life of 7.7+/-3.0 min. is determined for this previously unreported A = 177 beta-decay path, also involving 89-keV and 1003-keV gamma-ray transitions in association with hafnium X-rays. In addition, two previously unreported transitions (2016 and 2114 keV) were assigned to 182Hf as a result of their coincidence with Hf X-rays and the 98 keV 2+ → 0+ decay of that nucleus.
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Allen, Jessamyn Leigh. "Accretion flows and neutron star heating in low-mass X-ray binaries." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/115023.
Testo completoAbstract (sommario):
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2017.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 149-166).<br>X-ray binaries are excellent test beds for studies of high-energy accretion flows and the properties of compact objects. Neutron star (NS) low-mass X-ray binaries (LMXBs) vary in brightness by almost 8 orders of magnitude and are hosts to diverse accretion flows, transporting varying amounts of energy and mass toward the central NS, as well as expelling significant mass from the binary. This thesis aims to shed light on the accretion flow properties across the mass and luminosity scale, with particular emphasis on constraining the matter accreted on the neutron star surface and the resulting heating, which has important implications for measurements of the NS mass and radius. We have utilized X-ray instruments with substantially different sensitivities in flux and resolving power, each suited to our focused study of the accretion flows in a particular luminosity regime. In our study of the accretion disk wind in GX 13+1, we analyzed the Chandra High-Energy Transmission Grating spectrum of the NS binary accreting near its Eddington limit. We found multiple plasmas with different ionization states and velocities produce the observed absorption complex, in contrast to previous analyses that only found one absorption zone. The accretion disk wind expels mass from the disk at a rate comparable to the accretion onto the NS, and is consistent with a Comptonheated outflow, the driving mechanism likely behind all accretion disk winds in NS LMXBs and, possibly, all BH LXMBs. Frequent monitoring with the Swift X-Ray Telescope allowed us to observe SAX J1750.8-2900 in the relatively short-lived transition between outburst and quiescence. We found its X-ray spectrum softens towards lower luminosities, which can either be due to a radiatively-inefficient accretion flow or an increasing contribution of the boundary layer emission as the source's flux decreases. This work contributes to the establishment of spectral softening as a common property of the accretion flow in NS LMXBs between outburst and quiescence. We also found the transition does not produce significant NS heating. In our studies of NS LMXB quiescent emission, we utilized an XMM-Newton observation of Cen X-4 while the source was at its brightest quiescent luminosity ever recorded. We found the first evidence of multi-temperature thermal emission in a non-pulsing quiescent NS. We have interpreted the hotter of the two thermal components as a potential hotspot on the NS surface, indicative of a magnetically channeled accretion flow and motivation for further studies into NS heating in quiescence. Finally, we present the results from a recent XMM observation of the extremely faint system SAX J1810.8-2609. We find that the thermal component is consistent with a cooling NS radiating heat from nuclear reactions activated during outburst. We also present a revised estimate of the time-averaged mass accretion rate based on a more detailed outburst history and a range of outburst properties, finding the outburst history is in agreement with the quiescent thermal luminosity and discounting assertions of enhanced cooling mechanisms in the NS of SAX J1810.8-260.<br>by Jessamyn Leigh Allen.<br>Ph. D.
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Nättilä, J. (Joonas). "Mass and radius constraints for neutron stars using the cooling tail method." Master's thesis, University of Oulu, 2013. http://urn.fi/URN:NBN:fi:oulu-201312041966.
Testo completoAbstract (sommario):
Neutron stars (NS) are the most compact objects that can be directly observed. They can be used to study properties of matter at supranuclear densities. This in turn gives us information to separate between numerous theoretical equations of states of dense matter. Thermonuclear (type-I) X-ray bursts from low mass X-ray binaries can be used to address this issue. Some of these bursts can be so energetic that they cause the whole photosphere of the NS to expand. The cooling of these photospheric radius expansion bursts can be compared to theoretical atmosphere models to obtain the mass and radius measurements of the NS. These measurements can then be used to differentiate between the different equations of state.
We present a set of differential equations needed to compute these atmospheric models. We introduce an exact treatment of Compton scattering via the relativistic integral equation and an angle-dependent redistribution function. Using these equations, we can construct a set of atmosphere models in plane-parallel approximation in a local thermodynamical equilibrium for hot NSs. The emergent spectra is then fitted by a diluted blackbody to obtain the dilution factor w and the colour-correction factor f_c. On the other hand, the observed spectra from X-ray bursting neutron stars are close to thermal and can be fitted with a blackbody with two free parameters: the observed blackbody temperature T_bb and the normalization K. By equating the dilution factor w and the normalization K, we obtain a relation between the theoretical atmosphere models and the observations. This connection is the main idea of the so called cooling tail method. We then introduce a small correction to this method and discuss the consequences.
A common problem encountered using this method is that different bursts from a given system can yield completely different mass and radius measurements. This fact casts a doubt on the robustness of the entire method. We study the burst emission from 4U 1608--52 at various persistent fluxes. We find a strong dependence of the burst properties on the flux before the burst. Bursts that ignite during the hard state at a low accretion rate show strong evolution of the apparent blackbody radius which is consistent with the model predictions of the neutron star atmosphere models. On the other hand, bursts occurring during the soft state at a higher accretion rate show constant apparent radius, which is inconsistent with the models.
We then use the hard state bursts only to constrain the neutron star mass and radius from our set of sources. By taking only the physically relevant results into account, we also get information of the chemical composition of the atmosphere. This then gives us a way to conclude if the atmosphere is hydrogen- or helium-rich. After we know the chemical composition, we constrain the NS radius to be between 12 and 16 km. This implies a stiff equation of state of neutron star matter.
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Brinkfeldt, Klas. "Instrumentation for energetic Neutral atom measurements at Mars, Venus and The Earth." Doctoral thesis, Kiruna : Swedish Institute of Space Physics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-657.
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He, Yanyi. "2+1 correlation between neutral pions and charged hadrons in gold-gold collisions at center of mass energy = 200GeV." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1465704.
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Atanasov, Dinko [Verfasser], and Klaus [Akademischer Betreuer] Blaum. "Precision mass measurements for studies of nucleosynthesis via the rapid neutron-capture process : penning-trap mass measurements of neutron-rich cadmium and caesium isotopes / Dinko Atanasov ; Betreuer: Klaus Blaum." Heidelberg : Universitätsbibliothek Heidelberg, 2016. http://d-nb.info/1180615743/34.
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Song, Yang. "Unstructured Nodal Discontinuous Galerkin Method for Convection-Diffusion Equations Applied to Neutral Fluids and Plasmas." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/99291.
Testo completoAbstract (sommario):
In recent years, the discontinuous Galerkin (DG) method has been successfully applied to solving hyperbolic conservation laws. Due to its compactness, high order accuracy, and versatility, the DG method has been extensively applied to convection-diffusion problems. In this dissertation, a numerical package, texttt{PHORCE}, is introduced to solve a number of convection-diffusion problems in neutral fluids and plasmas. Unstructured grids are used in order to randomize grid errors, which is especially important for complex geometries. texttt{PHORCE} is written in texttt{C++} and fully parallelized using the texttt{MPI} library. Memory optimization has been considered in this work to achieve improved efficiency. DG algorithms for hyperbolic terms are well studied. However, an accurate and efficient diffusion solver still constitutes ongoing research, especially for a nodal representation of the discontinuous Galerkin (NDG) method. An affine reconstructed discontinuous Galerkin (aRDG) algorithm is developed in this work to solve the diffusive operator using an unstructured NDG method. Unlike other reconstructed/recovery algorithms, all computations can be performed on a reference domain, which promotes efficiency in computation and storage. In addition, to the best of the authors' knowledge, this is the first practical guideline that has been proposed for applying the reconstruction algorithm on a nodal discontinuous Galerkin method. TVB type and WENO type limiters are also studied to deal with numerical oscillations in regions with strong physical gradients in state variables. A high-order positivity-preserving limiter is also extended in this work to prevent negative densities and pressure. A new interface tracking method, mass of fluid (MOF), along with its bound limiter has been proposed in this work to compute the mass fractions of different fluids over time. Hydrodynamic models, such as Euler and Navier-Stokes equations, and plasma models, such as ideal-magnetohydrodynamics (MHD) and two-fluid plasma equations, are studied and benchmarked with various applications using this DG framework. Numerical computations of Rayleigh-Taylor instability growth with experimentally relevant parameters are performed using hydrodynamic and MHD models on planar and radially converging domains. Discussions of the suppression mechanisms of Rayleigh-Taylor instabilities due to magnetic fields, viscosity, resistivity, and thermal conductivity are also included.
This work was partially supported by the US Department of Energy under grant number DE-SC0016515.
The author acknowledges Advanced Research Computing at Virginia Tech for providing computational resources and technical support that have contributed to the results reported within this work. URL: http://www.arc.vt.edu<br>Doctor of Philosophy<br>High-energy density (HED) plasma science is an important area in studying astrophysical phenomena as well as laboratory phenomena such as those applicable to inertial confinement fusion (ICF). ICF plasmas undergo radial compression, with an aim of achieving fusion ignition, and are subject to a number of hydrodynamic instabilities that can significantly alter the implosion and prevent sufficient fusion reactions. An understanding of these instabilities and their mitigation mechanisms is important allow for a stable implosion in ICF experiments. This work aims to provide a high order accurate and robust numerical framework that can be used to study these instabilities through simulations.
The first half of this work aims to provide a detailed description of the numerical framework, texttt{PHORCE}. texttt{PHORCE} is a high order numerical package that can be used in solving convection-diffusion problems in neutral fluids and plasmas. Outstanding challenges exist in simulating high energy density (HED) hydrodynamics, where very large gradients exist in density, temperature, and transport coefficients (such as viscosity), and numerical instabilities arise from these region if there is no intervention. These instabilities may lead to inaccurate results or cause simulations to fail, especially for high-order numerical methods. Substantial work has been done in texttt{PHORCE} to improve its robustness in dealing with numerical instabilities. This includes the implementation and design of several high-order limiters. An novel algorithm is also proposed in this work to solve the diffusion term accurately and efficiently, which further enriches the physics that texttt{PHORCE} can investigate.
The second half of this work involves rigorous benchmarks and experimentally relevant simulations of hydrodynamic instabilities. Both advection and diffusion solvers are well verified through convergence studies. Hydrodynamic and plasma models implemented are also validated against results in existing literature. Rayleigh-Taylor instability growth with experimentally relevant parameters are performed on both planar and radially converging domains. Although this work is motivated by physics in HED hydrodynamics, the emphasis is placed on numerical models that are generally applicable across a wide variety of fields and disciplines.
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Simutkin, Vasily. "Fragment Mass Distributions in Neutron-Induced Fission of 232Th and 238U from 10 to 60 MeV." Doctoral thesis, Uppsala universitet, Tillämpad kärnfysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-134952.
Testo completoAbstract (sommario):
Since its discovery, the phenomenon of nuclear fission is the object of extensive theoretical and experimental studies. However, we are still far from a complete understanding of the fission process. Nuclear theory can satisfactorily explain the process of neutron-induced fission at thermal neutron energies, but it meets problems at high neutron energies. However, new applications are nowadays developed involving neutron-induced fission in this energy domain. An example of such an application is accelerator-driven systems (ADS) which are dedicated to transmutation of highly radioactive nuclear waste. Conceptual studies of ADS require new nuclear data on neutron-induced reactions within a wide incident energy range. Along with structural, spallation target and other materials, data on neutron-induced fission are especially required for two nuclides, 232Th and 238U. At present, however, there are no published neutron-induced fission yield data for either 232Th or 238U at energies above 20 MeV. In this thesis, I present measurements of fission fragment mass yields at neutron energies from 10 to 60 MeV for 232Th and 238U. The experiment was done at the Louvain-la-Neuve quasi-monoenergetic neutron beam facility. A multi-section Frisch-gridded ionization chamber was used as the fission fragment detector. The fission fragment mass yields were measured at peak neutron energies of 33, 45, and 60 MeV. In addition, data for the neutron-energy intervals 9-11, 16-18, and 24-26 MeV were also extracted from the low-energy tail. The measurement results show that the symmetric fission component increases with incident neutron energy for both uranium and thorium, but it is more enhanced for thorium. The uranium results were compared to the only existing set of experimental data for neutron energies above 20 MeV. Reasonable agreement was found. However, our data show a lower symmetric fission component. For thorium, the present data are the first above 20 MeV. Model calculations with the TALYS code have also been done. This code is based on the multi-modal random neck-rupture model extended for higher excitation energies. We included a phenomenological model into the code and achieved a good description of our experimental results.<br>Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 723
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Shirley, Robert Edward 1972. "Mass transfer and accretion in the eccentric neutron-star binary Circinus X-1." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/47699.
Testo completoAbstract (sommario):
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1998.<br>Includes bibliographical references (p. 199-206).<br>I have carried out a project to study the eccentric neutron-star binary Circinus X-1 through an extensive series of observational studies with the Rossi X-ray Timing Explorer satellite and through theoretical computer models I developed to explore mass transfer and evolution in an eccentric binary. We also organized two multi-frequency campaigns to study correlated variability in different frequency bands. The X-ray observations showed that the intensity of Cir X- 1 currently maintains a bright baseline level, with strong flares occurring after phase zero of each 16.55-day cycle of the source. This behavior is thought to be due to enhanced mass transfer occurring near periastron of a highly eccentric binary orbit. Dips below the baseline intensity level also occur near phase zero. I modeled the evolution of the energy spectrum during dips with a variably absorbed bright component plus a fainter unabsorbed component. I show that variability not attributable to absorption dips is related to the spectral/intensity states of the "Z source" class of low-mass X-ray binaries (LMXBs), namely motion along (or shifts of) the horizontal, normal, and flaring branches of the "Z" track in color-color and hardness-intensity diagrams. I found rapid X-ray variability properties associated with each spectral/intensity state: On the horizontal branch, quasi-periodic oscillations (QPOs) in the X-ray intensity shift in frequency from 1.3 to 35 Hz. On the normal branch, a different QPO occurs at about 4 Hz. On the flaring branch only strong aperiodic variability occurs. I modeled the evolution of the energy spectra associated with each of these branches. To study mass transfer in an eccentric binary, I developed computer codes for transfer via Rochelobe overflow and from a stellar wind. I derive theoretical mass accretion profiles and compare them to the observed profile of the X-ray intensity. In order to explore the possible evolutionary history of Circinus X-1, I developed a binaryevolution computer code for a neutron-star and low-mass companion in an eccentric orbit. I use this code in a population-synthesis study to show that the number of systems in the Galaxy expected to resemble Cir X-1 is of order unity, consistent with its unique status as an LMXB with high eccentricity.<br>by Robert E. Shirley.<br>Ph.D.
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Joshi, Ubisha. "Characterization of Ionic Liquid As a Charge Carrier for the Detection of Neutral Organometallic Complexes Using Electrospray Ionization Mass Spectrometry." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc149615/.
Testo completoAbstract (sommario):
A novel application of ionic liquid as a charge carrier for the analysis and detection of neutral organometallic complexes using a mass spectrometer has been presented. The mass spectrometer detects only charged compounds which raise a difficulty in analyzing a neutral molecule that lacks a basic site to associate with charge. Therefore, an effective way of providing charge has always been an area of keen interest in the field of mass spectrometry. Ionic liquids have a very fascinating property of forming a cation-? interaction with other molecules to give a charged complex. In order to take advantage of this, it is important to know the geometric structure of the complex. Advanced methodologies like hydrogen-deuterium exchange and computational calculations have been used assisting in better understanding of the structure of the ionic liquid complexes.
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Dominguez, David Aaron Matzner. "Search for neutral Higgs Bosons in e+e- interactions at center-of-mass energies between 130 GeV and 183 GeV /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9907602.
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Bogdanov, Slavko, Craig O. Heinke, Feryal Özel, and Tolga Güver. "NEUTRON STAR MASS–RADIUS CONSTRAINTS OF THE QUIESCENT LOW-MASS X-RAY BINARIES X7 AND X5 IN THE GLOBULAR CLUSTER 47 TUC." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/622762.
Testo completoAbstract (sommario):
We present Chandra/ACIS-S subarray observations of the quiescent neutron star (NS) low-mass X-ray binaries X7 and X5 in the globular cluster 47 Tuc. The large reduction in photon pile-up compared to previous deep exposures enables a substantial improvement in the spectroscopic determination of the NS radius and mass of these NSs. Modeling the thermal emission from the NS surface with a non-magnetized hydrogen atmosphere and accounting for numerous sources of uncertainties, we obtain for the NS in X7 a radius of R = 11.1(-0.7)(+0.8) km for an assumed stellar mass of M = 1.4 M-circle dot (68% confidence level). We argue, based on astrophysical grounds, that the presence of a He atmosphere is unlikely for this source. Due to the excision of data affected by eclipses and variable absorption, the quiescent low-mass X-ray binary X5 provides less stringent constraints, leading to a radius of R = 9.6(-1.1)(+0.9) km, assuming a hydrogen atmosphere and a mass of M. =. 1.4 Me. When combined with all existing spectroscopic radius measurements from other quiescent low-mass X-ray binaries and Type I X-ray bursts, these measurements strongly favor radii in the 9.9-11.2 km range for a similar to 1.5 M-circle dot NS and point to a dense matter equation of state that is somewhat softer than the nucleonic ones that are consistent with laboratory experiments at low densities.
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Brodeur, Maxime. "First direct mass measurement of the two and four neutron halos ⁶He and ⁸He using the TITAN Penning trap mass spectrometer." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/24251.
Testo completoAbstract (sommario):
Neutron halo nuclei are distinguished by an extended matter radius and a small neutron separation energy compared to other nuclei. They are comprised of a core surrounded by at least one loosely bound neutron forming a halo structure. The size of the core is associated with the charge radius while the extent of the diffuse halo region, owing to quantum mechanical leakage of the valence neutron(s) wavefunction, depends exponentially on their separation energy. Predicting accurately the extreme behaviour of these nuclei is challenging for nuclear theory. These nuclei provide an ideal testing grounds of nuclear theory, leading to a deeper understanding of the strong force and nuclear interactions. Halo nuclei can be found amongst light nuclei and hence have few (A~10) nucleons. This makes them treatable using ab-initio methods. To test these theoretical approaches and consequently refine our knowledge of the nucleus, one requires both precise and accurate experimental data, such as ground state properties: masses (or separation energies) and sizes (charge and matter radii). In this thesis we present the mass measurement of the two- and four-neutrons halo ⁶,⁸He (t₁/₂ = 808 ms, 119 ms respectively) using the TITAN Penning trap as well as systematic studies of this system. The obtained mass are m(⁶He) = 6 018 885.883(57) u and m(⁸He) = 8 033 934.435(114) u. These values show deviations with literature of 4.0 and 1.7σ. Using our new masses, we re-evaluated the charge radius and obtained (rc²)¹/²(⁶He) = 2.056(10) fm and (rc²)c¹/²(⁸He) = 1.955(18) fm, which correspond to an improvement in the precision of 9% and 36% respectively. Using the charge radii and the binding energies of ⁶,⁸He, obtained from our more precise and accurate masses, we show that one can test the predictions of advanced ab-initio nuclear theories for these extreme systems. Using such comparison, we point to the needs of three-body interactions in order to explain the experimental observables.
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Griffin, Jeffrey Cliff. "Decay of mass-separated [superscript]195Bi to levels in [superscript]195Pb : collinear laser spectroscopy on mass-separated neutron-deficient lead isotopes." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/27319.
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Matoš, Milan. "Isochronous mass measurements of short-lived neutron rich nuclides at the FRS-ESR facilities." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972168656.
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Dietrich, Tim [Verfasser], Bernd [Gutachter] Brügmann, Stephan [Gutachter] Rosswog, and Mark [Gutachter] Hannam. "Binary neutron star merger simulations / Tim Dietrich ; Gutachter: Bernd Brügmann, Stephan Rosswog, Mark Hannam." Jena : Friedrich-Schiller-Universität Jena, 2016. http://d-nb.info/1177612704/34.
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Mayet, Pascale. "Isomers populated by projectile fragmentation in the neutron-rich A=180-200 mass region." Université Louis Pasteur (Strasbourg) (1971-2008), 2001. http://www.theses.fr/2001STR13131.
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Clark, Michael A. R. "Application of thermal neutron radiography for the mass transport of moisture through freezing soil." Thesis, Aston University, 1989. http://publications.aston.ac.uk/14320/.
Testo completoAbstract (sommario):
This thesis reports on the development of a technique to evaluate hydraulic conductivities in a soil (Snowcal) subject to freezing conditions. The technique draws on three distinctly different disciplines, Nuclear Physics, Soil Physics and Remote Sensing to provide a non-destructive and reliable evaluation of hydraulic conductivity throughout a freezing test. Thermal neutron radiography is used to provide information on local water/ice contents at anytime throughout the test. The experimental test rig is designed so that the soil matrix can be radiated by a neutron beam, from a nuclear reactor, to obtain radiographs. The radiographs can then be interpreted, following a process of remote sensing image enhancement, to yield information on relative water/ice contents. Interpretation of the radiographs is accommodated using image analysis equipment capable of distinguishing between 256 shades of grey. Remote sensing image enhancing techniques are then employed to develop false colour images which show the movement of water and development of ice lenses in the soil. Instrumentation is incorporated in the soil in the form of psychrometer/thermocouples, to record water potential, electrical resistance probes to enable ice and water to be differentiated on the radiographs and thermocouples to record the temperature gradient. Water content determinations are made from the enhanced images and plotted against potential measurements to provide the moisture characteristic for the soil. With relevant mathematical theory pore water distributions are obtained and combined with water content data to give hydraulic conductivities. The values for hydraulic conductivity in the saturated soil and at the frozen fringe are compared with established values for silts and silty-sands. The values are in general agreement and, with refinement, this non-destructive technique could afford useful information on a whole range of soils. The technique is of value over other methods because ice lenses are actually seen forming in the soil, supporting the accepted theories of frost action. There are economic and experimental restraints to the work which are associated with the use of a nuclear facility, however, the technique is versatile and has been applied to the study of moisture transfer in porous building materials and could be further developed into other research areas.
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Ansari, Saba. "Shape evolution in neutron-rich Zr, Mo and Ru isotopes around mass A=100." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS384/document.
Testo completoAbstract (sommario):
La forme d’un noyau, ou la déviation de la distribution en masse par rapport à une forme sphérique, est une des propriétés fondamentales du noyau. Elle est gouvernée à la fois par des effets macroscopiques et microscopiques, tels que l'énergie de liaison donnée par le modèle de la goutte liquide ou la structure en couche du noyau, respectivement. L’étude de la forme des noyaux exotiques par spectrométrie gamma permet de tester finement différents modèles théoriques initialement développés pour les noyaux stables. L’objectif de cette thèse est l’étude de l’évolution de la forme des noyaux exotiques riches en neutrons dans les chaînes isotopiques allant du Zr (Z=40) au Pd (Z=46). Le plus souvent, la forme des noyaux évolue lentement de la forme sphérique, près des fermetures de couche ou des noyaux magiques (ou doublement magiques), à des formes allongées (prolate), pour des noyaux avec de nombreux nucléons de valence. Cependant, Les noyaux auxquels nous nous intéressons ont tendance à avoir des états excités qui évoluent rapidement en fonction du nombre de neutrons, ce qui peut être interprété comme des variations rapides de la forme du noyau. Ceci inclue dans de rares cas l'observation d'états de forme aplatie (oblate) et triaxiale. Jusqu'à présent, les propriétés connues de ces noyaux se limitent (principalement) aux énergies d'excitation. Les informations sur le degré de collectivité nucléaire (que l'on peut déduire de la durée de vie des états excités) sont rares, tandis que les informations directes de forme sont pratiquement inexistantes. L'estimation la plus simple de la déformation nucléaire dans les noyaux pairs peut être obtenue à partir de l'énergie du premier état 2⁺. Pour les isotopes du Sr (Z = 38) et du Zr (Z = 40), il a été observé que cette énergie diminue considérablement à N = 60, alors que son évolution est beaucoup plus progressive pour les isotopes du Mo (Z = 42). Des mesures précises de durée de vie constituent un élément clé de l'étude systématique de l'évolution de la déformation nucléaire et du degré de collectivité dans cette région. Des noyaux riches en neutrons dans la région de masse A = 100-120 ont été peuplés par la réaction de fusion-fission d'un faisceau de ²³⁸U à 6,2 MeV/u sur une cible ⁹Be. Le noyau composé ²⁴⁷Cm était produit à une énergie d'excitation de ∼45 MeV avant de fissionner. Le dispositif expérimental utilisé pour cette étude comprenait le spectromètre de masse de haute résolution VAMOS pour l'identification les noyaux en Z et A, le réseau de 35 détecteurs au germanium AGATA (Advanced γ-ray Tracking Array) AGATA, pour la spectroscopie de rayons γ, ainsi qu'un mécanisme de "plunger" pour mesurer la durée de vie jusqu'à quelques ps par la méthode RDDS (Recoil Distance Doppler Shift). De plus, la cible était entourée de 24 détecteurs LaBr₃ (Bromure de lanthane) pour mesurer des durées de vie plus de 100 ps avec la méthode du "fast-timing". La combinaison de spectromètres sophistiqués utilisée dans cette expérience a permis de mesurer des durées de vie d'états nucléaires allant de 100 picosecondes à quelques picosecondes. Dans cette thèse, nous exposerons de nouveaux résultats pour les états à courte durée de vie dans les noyaux riches en neutrons A∼100, en mettant l'accent sur les chaînes des Zr, Mo et Ru. Nous discuterons des techniques expérimentales utilisées pour évaluer les durées de vie ainsi que l'interprétation de celles-ci à l'aide de modèles de structures nucléaires récents<br>The shape of an atomic nucleus, ie. the deviation of its mass distribution from sphericity, is a fundamental property and governed by a delicate interplay of macroscopic and microscopic effects, such as the liquid-drop like binding energy and the nuclear shell structure, respectively. Studying nuclear shape properties using gamma ray spectroscopic methods allows detailed tests of different nuclear models, which were originally developed for stable nuclei. We proposed a project to study the evolution of nuclear shapes in exotic nuclei, far from the valley of stability, specifically in neutron-rich nuclei in the isotopic chains from Zr (Z=40) to Pd (Z=46). Usually, nuclear shapes are slowly evolving from spherical shapes around closed-shell or (doubly-) magic nuclei to elongated (prolate) shapes in nuclei with many valence nucleons. The nuclei of interest, however, show rapidly evolving patterns of excited states, which can be interpreted as rapid variations of the nuclear shape, including the rare observation of oblate (disk-like) and triaxial shapes. So far the known properties for these nuclei are (mainly) limited to excitation energies. Information on the nuclear collectivity, which can be deduced from the lifetime of the excited states, are sparse, while direct information of the shape is practically non existing. The simplest estimate of nuclear deformation in even-even nuclei can be obtained from the energy of the first 2⁺ state. For Sr (Z = 38) and Zr (Z = 40) isotopes this energy is observed to decrease dramatically at N = 60, while its evolution is much more gradual in Mo nuclei (Z = 42). Precise lifetime measurements provide a key ingredient in the systematic study of the evolution of nuclear deformation and the degree of collectivity in this region. Neutron-rich nuclei in the mass region of A = 100-120 were populated through the fusion-fission reaction of a ²³⁸U beam at 6.2 MeV/u on a ⁹Be target. The compound nucleus ²⁴⁷Cm was produced at an excitation energy of around 45 MeV before undergoing fission. The setup used for this study comprised the high-resolution mass spectrometer VAMOS in order to identify the nuclei in Z and A, the Advanced gamma ray Tracking Array AGATA of 35 germanium detectors to perform gamma ray spectroscopy, as well as a plunger mechanism to measure lifetimes down to a few ps using the Recoil Distance Doppler Shift method (RDDS). In addition, the target was surrounded by 24 Lanthanum Bromide (LaBr₃) detectors for a fast-timing measurement of lifetimes longer than 100 ps. The sophisticated set of spectrometers used in this experiment allowed measurement of nuclear lifetimes in a range from 100’s of picoseconds down to a few picoseconds. In this thesis, we will report on new lifetime results for short-lived states in neutron-rich (A ~ 100) nuclei, with an emphasis on the Zr, Mo and Ru chains. We will discuss the experimental techniques used to evaluate the lifetimes as well as their interpretation in terms of state-of-the-art nuclear structure models
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Collins, S. P. "Coincidence and directional correlation studies of '1'1'8Te, and a search for mixed-symmetry states in the A-50 mass region." Thesis, University of Sussex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378260.
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Mougeot, Maxime. "Nuclear Collectivity Studied through High Precision Mass Measurements of Neutron-rich Argon and Chromium Isotopes." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS455/document.
Testo completoAbstract (sommario):
Le lien étroit existant entre la masse d'un noyau et son énergie de liaison fait de la masse un observable incontournable pour enrichir notre compréhension de l'évolution de la structure nucléaire dans des régions de la carte des noyaux éloignées de la vallée de la stabilité. Dans cette thèse deux régions présentant d'importants changements structurales sont étudiés à travers des mesures de masses de haute précision effectuées à ISOLDE/CERN avec le spectromètre ISOLTRAP. De nombreux résultats de spectroscopie nucléaire indiquent que la chaîne isotopique du chrome présente les changements structurales les plus importants dans toute la région de déformation nucléaire observée au sud du nickel 68. Cette thèse présente les premières mesures de haute précision des isotopes 58-63Cr grâce à des techniques de spectrométrie de masse de pointe faisant appel à l'utilisation d'un piège de Penning ainsi qu'à un spectromètre en temps de vol de type MRToF-MS. Les mesures ainsi obtenues sont jusqu'à 300 fois plus précises que celles disponibles dans la littérature actuelle. Au contraire des résultats précédents, ces nouvelles mesures suggèrent une évolution progressive de l'état fondamental des chromes vers la déformation aux abords de N=40. La question de la persistance de la fermeture de couche à N=28 dans la chaine de l'argon est aussi abordée dans le cadre de cette thèse de doctorat à travers la mesure des isotopes 46-48 de l'argon. Les résultats d'une précision améliorée confirment la présence d'une forte fermeture de couche à N=28 dans l'argon. Pour chaque jeu de données la procédure d'analyse est détaillée. L'implication pour la physique nucléaire des résultats expérimentaux obtenus sont discutés de manière phénoménologique ainsi qu'à travers des modèles représentant l'état de l'art de la recherche en physique nucléaire théorique<br>Due to their inherent relationship with the binding energy, nuclear masses are the fingerprint of all the interactions taking place within the nucleus. As such, precise and accurate mass values are an essential ingredient to the comprehensive understanding of nuclear phenomena in exotic regions of the chart of nuclides. In this thesis, two key regions exhibiting dramatic structural evolution are investigated by means of high precision mass measurements performed with the online mass spectrometer ISOLTRAP at ISOLDE/CERN. Numerous spectroscopy results indicate that the chromium isotopic chain exhibits the most dramatic structural changes within the region situated south of 68Ni. This thesis reports on the first high-precision mass measurements of the neutron-rich 58-63Cr isotopes using the well established Penning trap mass spectrometry technique as well as the MRToF-MS technique pioneered at ISOLTRAP in recent years. The obtained mass values are up to 300 times more precise than the ones currently available in the literature. At odds with previous results, the new mass values exclude a sudden onset of ground-state collectivity rather favouring a smooth transition towards deformation approaching N=40. The question of the persistence of the N=28 shell closure in the Argon chain is also studied in this PhD work through the measurement of the neutron-rich 46-48Ar isotopes. The results of improved precision confirm the presence of a strong N=28 shell closure in the Argon chain. For both datasets, the detailed data analysis procedure will be presented. The implication of the obtained mass values for nuclear structure will be discussed through a phenomenological discussion of the binding energy trend. The results will also be discussed in the light of state of the art nuclear models including results from the promising valence-space formulation of the ab-initio IM-SRG formalism
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Troyer, Jon S. "Spectral-Timing Analysis of Kilohertz Quasi-Periodic Oscillations in Neutron Star Low Mass X-Ray Binaries." Thesis, Wayne State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10747548.
Testo completoAbstract (sommario):
<p> Kilohertz quasi-periodic oscillations or kHz QPOs are X-ray intensity variations observed in neutron star low-mass X-ray binary (LMXB) systems. In such systems, matter is transferred from a secondary low-mass star to a neutron star via the process of accretion. kHz QPOs occur on the timescale of the inner accretion flow and may carry signatures of the physics of strong gravity (<i>c<sup>2</sup> ~ GM/R</i>) and possibly clues to constraining the neutron star equation of state (EOS). No model to date has been able to illuminate the origin of kHz QPOs. Spectral-timing is a set of analysis techniques useful in deriving information about the nature of physical processes occurring within the accretion flow on the timescale of the kHz QPO. We present a comprehensive study of spectral-timing products of kHz QPOs from systems where data is available in NASA’s <i>Rossi X-ray Timing Explorer</i> (<i>RXTE</i>) archive to demonstrate the promise of these techniques and to gain insights regarding the origin of kHz QPOs. Using data averaged over the entire <i>RXTE</i> archive, we show correlated time-lags as a function of QPO frequency and energy, as well as energy-dependent covariance spectra for the various LMXB systems where spectral-timing analysis is possible. The similarity in trends in all sources suggest a common physical origin for kHz QPOs across the population. The diferences in results between lower and upper kHz QPOs lend further support to the evidence of the differing nature of the lower and upper kHz QPOs.</p><p>
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GUIMARAES, GUILHERME M. "Avaliação da concentração de metais e elementos traço em amostras de sedimento do reservatório Guarapiranga, São Paulo-SP, Brasil." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10002.
Testo completoAbstract (sommario):
Made available in DSpace on 2014-10-09T12:33:42Z (GMT). No. of bitstreams: 0<br>Made available in DSpace on 2014-10-09T14:04:01Z (GMT). No. of bitstreams: 0<br>Dissertação (Mestrado)<br>IPEN/D<br>Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Sugimura, Hitoshi. "Search for 6ΛH hypernucleus by the (π-,K+) reaction at J-PARC". 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188482.
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Trach, Maria S. "A Q-study of the effects of Novy Kanal reporters' gender on their preferences in coverage of gender neutral issues." Virtual Press, 2003. http://liblink.bsu.edu/uhtbin/catkey/1272771.
Testo completoAbstract (sommario):
It has been established that regardless of the fact that journalism in not a one-gender- profession anymore, news is still defined from a male perspective. A number of studies through the years examined the news content and determined that it continued male.Though news veterans acknowledge significant changes in m coming of women to the newsrooms, those changes sometimes are hard to detect on the personal level. Male and female reporters claim that even though gender can affect their approach to reporting, the final product they produce does not have gender marked on it. The present Q study is examined whether gender has an influence on reporter’s preferences in choosing a topic while covering gender-neutral issues. The participants of the study were 17 employees of the major Ukrainian TV channel "Novy Kanal.” In February of 2003 they were e-mailed 50 story ideas (constructed to include either two of five news values, such as magnitude, conflict, oddity, prominence and impact) and asked them to sort them according to their desire to cover these topics. Fourteen journalists and three editors responded. In May 2003 the sorts were analyzed with the PQMethod program, and three factors emerged representing three groups of people (Maximalists, Conservatives and Commoners) with different attitudes toward gender-neutral issues. The Maximalists, the largest group consisted only of reporters, were a sensation-oriented group of people. Magnitude and conflict were the most important news values for this factor. The Conservatives were characterized by the strong inclination towards official news, where conflict and impact played an important role. The Commoners preferred the human interest stories with oddity and impact.Each group consisted of an even number of men and women, and thus the study failed to support the notion that males and females share different attitudes toward neutral issues. No discrimination was evident toward women stories on the “Navy Kanal” TV channel. Surprisingly, men were more likely than women to choose active participants or acted as newsmakers.The findings suggested that it is women who are creating problems for the feminist movement, not men. Women correspondents at "Novy Kanal" are more immersed in patriarchal values than their male colleagues.<br>Department of Journalism
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Moussaoui, Roba. "Study of negative ions surface production in cesium-free H2 and D2 plasmas." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0328/document.
Testo completoAbstract (sommario):
Cette thèse porte sur l’étude de la production de surface des ions négatifs (IN) pour des applications dans la fusion thermonucléaire. Ce travail a été réalisé à l'aide d'une source plasma PHISIS. Les IN formés en surface de l'échantillon sont collectés et analysés avec un spectromètre de masse (SM). La fonction de la distribution en énergie des ions négatifs FDEIN est mesurée. Dans cette thèse, une technique de polarisation DC pulsée est introduite pour permettre l'étude de la production d'IN en surface sur des échantillons isolants comme le diamant. Un modèle qui calcule le taux de changement de la variation de la tension sur une surface isolante polarisée en mode pulsé est développé. De façon surprenante, la production d’IN en surface sur un diamant dopé au bore ou non dopé est beaucoup plus élevée en mode pulsé qu'en mode continu. Il est traité également la production d’IN en surface dans les conditions de faible tension de polarisation. Le meilleur rendement d’IN mesuré à faible polarisation est obtenu avec du diamant dopé au bore (BDD) et il est 2 fois plus élevé que celui mesuré sur HOPG (high oriented pyrolitic graphite). L'analyse de la production d’IN en surface à différents polarisations pour différents matériaux a été effectuée afin de corréler l'évolution du rendement d’IN aux changements d'état de surface. Une étude approfondie de la production en surface d'IN a été réalisée sur la surface de Nanoporous 12 CaO. 7Al2O3 electride surface. L'influence des conditions expérimentalles sur le rendement en IN a été étudiée. Dans cette contribution, nous montrons que ce matériau pourrait potentiellement être utilisé dans les sources d'ions négatifs sans césium<br>This thesis deals with negative ions (NI) surface production for applications in thermonuclear fusion. This work was conducted using a plasma source PHISIS. NI formed on a negatively biased sample surfaceare collected and analyzed with energy mass spectrometer (MS). Negative ion distribution function NIEDF is measured. A SIMION calculation was done to have a complete idea about MS transmission effect on the NIEDF. In the course of this thesis, a DC pulsed bias technique is introduced to enable the study of negative ion surface production on insulating samples as non-doped diamond layers. A model that calculate the rate of change of bias on insulator surface biased in pulsed mode is developed. Surprisingly, negative-ion surface production on boron-doped or non-doped diamond is much higher in pulsed mode than in continuous mode. This thesis deals also with negative ion surface production in low bias condition. The best NI yield measured at low bias is obtained with Boron doped diamond (BDD) ant it is 2 times higher than the one measured on HOPG (highly oriented pyrolytic graphite) surface. Analysis of NI surface production at different surface bias for different material were performed in order to correlate the NI yield evolution to the surface state changes.An extensive study of NI surface production was performed on Nanoporous 12CaO.7Al2O3 electride surface. The influence of surface temperature, bias and plasma exposure time on negative-ion yield was investigated. In this contribution, we show that the electride material has potentials to be used as a production surface in negative ion sources devoted to nuclear fusion application