Several large sources of 1ce nuclei were identified for the Wasatch Weather Modification Experimental Area. When stable air masses remained over the area for several days, ice nuclei concentrations as large as 1750 per liter (measured at -20 C) were found at the surface. ConcentralX tions as large as 6000 per liter were measured with an airborne 1ce nuclei counter over the smelter industry of the Salt Lake Valley. Ice nuclei concentrations during storm periods were usually less than 3 per liter, indicating an excellent potential for increasing precipitation amounts over the Wasatch Mountains through the release of artificial ice nuclei. Ice nuclei measurements taken during and following seeding activities indicate that nuclei are not being trapped in the Cache Valley and are not being funnelled into areas upwind of the seeding generators. The measure ments also indicated that nuclei are getting into the seeding area, at least at the ground level. Residual lee nuclei were found in the experimental area--an average oF 7.5 hours for ground seeders and 4.6 hours For airborne seeders--following seeding activities. Stability, wind direction, and cloud top temperatures were found to be the meteorological conditions most closely related to ice nuclei concentrations although this could not be shown through the use of statistical tests.

Active galactic nuclei (AGN) ubiquitously show outflows. It is now widely recognized that these outflows are key components in the evolution of super-massive black holes and their host galaxies. As important as these outflows are, we still lack sufficient understanding of their structure and energetics. The majority of the work presented in this thesis involved photoionization modeling of AGN outflows along with analysis of density diagnostics in order to determine the distances and energetics of observed outflows. The main findings of these analyses are that 1) outflows are often at distances of hundreds to thousands of parsecs from the central supermassive black hole and 2) quasars outflows can be sufficiently powerful to provide feedback in galactic evolution scenarios. We also find in some cases that the recombination timescales of metal ions are long compared with the flux variability timescales. The large distances we find provide a challenge to current outflow models. For example, these outflows cannot be connected with an accretion disk surrounding the supermassive black hole as assumed in some models. Furthermore, the outflows may be out of equilibrium as we find in Mrk 509. In this case, a thorough understanding of time-dependent photoionization effects is necessary. In this thesis, I include early steps toward understanding time-dependent photoionization as well as ionization studies of accretion disk winds. The main results of these theoretical studies is that 1) the appearance of multiple ionization components in an outflow can be an artifact of the incorrect assumption that the outflow is in ionization equilibrium and 2) the shielding gas required in accretion-disk-wind models should have a clear signature in UV spectra, but none has been observed to date. / Ph. D.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18080号 / 理博第3958号 / 新制||理||1570(附属図書館) / 30938 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 上田 佳宏, 准教授 岩室 史英, 教授 長田 哲也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20171号 / 理博第4256号 / 新制||理||1612(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 永江 知文, 教授 中家 剛, 教授 大西 明 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20898号 / 理博第4350号 / 新制||理||1624(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 田中 貴浩, 准教授 樽家 篤史, 教授 川合 光 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Previously developed Zn decay schemes were limited by a number of factors including low production rates and detector efficiencies making it impossible to place weak transitions. Furthermore, most of the published results are from initial exploratory measurements while subsequent studies in this region either ignored the data obtained from the Zn decays or was not analyzed due to the focus on more exotic nuclei. In the current experiments, a nearly pure beam of the Cu isotope was provided by the Holifield Radioactive Ion Beam Facility (HRIBF) for the study of the Cu -> Zn -> Ga -> Ge β-decay chain using the Low-energy Radioactive Ion Beam Spectroscopy Station (LeRIBSS) setup. The high efficiency of the detector system along with the nearly pure primary beam allowed a detailed study of the γ-ray emission from the decay chain without any member of the decay chain being dominant. The γγ and βγ gamma coincidence data obtained from the experiment was used to develop revised decay schemes in which statistical significance for each observed coincidence peak was determined quantitatively. Presented in this work are updated and expanded decay schemes with new energy levels along with new βeeding intensities and logft values for the Zn -> Ga decays. In each of the Zn decays, a number of new energy levels and transitions have been proposed to the structure of respective Ga isotopes in addition to correcting discrepancies from previous works. The 74Zn β decay now has 29 new γ rays assigned to 74Ga in addition to previous 35 transitions (Winger et al., 1989} depopulating 19 energy states, including 7 new ones. The maximum level energy is increased from previous 1086- to 1555-keV. Similarly, the updated 75Zn decay scheme has its level energy increased from previous (Ekstrom et al., 1986) 3209- to 3924-keV, with addition of 37 new energy levels and 53 new γ rays. New decay scheme for 76Zn is established up to 2603 keV, similar to previous literature (Ekstrom et al.) with addition of 4 new energy levels and total of 5 new γ-ray transitions. In case of 77Zn decay, we proposed the decay scheme up to 3948 keV with addition of 8 new energy levels and 10 new γ-ray transitions.

Effective field theory (EFT) provides a framework to exploit separation of scales in the physical system in order to perform systematic model-independent calculations. There has been significant interest in applying the methods of EFT to halo nuclei. Using halo effective field theory, I provide a model-independent calculation of the radiative neutron capture on lithium-7 over an energy range where the contribution from the 3+ resonance becomes important. This reaction initiate the sequence in the carbon-nitrogen-oxygen (CNO) cycle in the inhomogeneous BBN models, and determine the amount of heavy element production from its reaction rate. One finds that a satisfactory description of the capture reaction, in the present single-particle approximation, suggests the use of a resonance width about three times larger than the experimental value. Power counting arguments that establish a hierarchy for the electromagnetic one- and two-body currents is also presented. The neutron capture of Lithium7 calculation has direct impact on the proton capture on beryllium7 which plays an important role in the neutrino experiments studying physics beyond the Standard Model of particle physics. As a further study of halo nuclei interactions, the cross section of radiative capture of a neutron by carbon-14 is calculated by considering the dominant contribution from electric dipole transition. This is also a part of the CNO cycle and as the slowest reaction in the chain it limits the flow of the production of heavier nuclei A > 14. The cross section is expressed in terms of the elastic scattering parameters of an effective range expansion. Contributions from both the resonant and non-resonant interactions are calculated. Significant interferences between these leads to a capture contribution that deviates from a simple Breit-Wigner resonance form. Using EFT, I present electromagnetic form factors of several halo nuclei. The magnetic dipole moment and the charge radii of carbon-15, beryllium-11, and carbon-19 halo systems are considered. Prediction is made for the magnetic moment in the leading order. I can only provide some estimates for the form factors in next-to-leading order where two-body currents appear. The estimates are based on power counting unless the effective range and the magnetic moment are known. Charge radii for three systems have also been estimated at LO and NLO.

<p> Thermal neutron capture studies have been made of the odd-odd nuclei, 20F, 24Na, 28Al, 32P, 36Cl and 40K. The gamma ray spectra have been studied using a Ge(Li) pair spectrometer and revised decay schemes are presented for these nuclei. The Q-values and gamma ray multiplicities have been obtained for the reactions studied. The average partial widths for primary Ml and El transitions have been calculated for the six nuclei and compared with the theoretical estimates. The features of the capture gamma ray spectra are discussed and it is observed that for the six nuclei studied, the total intensity in the spectrum above the energy of 0.3 times the Q-value is nearly the same (~1.4 photons/capture).</p> / Thesis / Doctor of Philosophy (PhD)

<p> In vivo and in vitro studies on the biosynthesis of vasopressin in the supraoptic nuclei of the dog and guinea pig1 using 35s-cysteine and 3H-tyrosine have suggested that vasopressin could be synthesized by wa;y of a precursor, which is modified to release active hormone. In vivo injection of 3H-tyrosine into the cerebrospinal fluid of rats2 had resulted in incorporation of the label into both oxytocin and vasopressin. In this work, an attempt was made to develop an in vitro system for the biosynthesis of oxytocin. Incubations of either 3H-isoleucine or 14c-leucine with rat hypothalamic neuronal perikaya, ribosomes and cell sap, cell sap, fractions of cell sap and homogenate, and incubations of 3H-isoleucine and l4C-leucine with rat hypothalamic tissue fragments were analyzed for the incorporation of label into purified hormone. Gel filtration, partition chromatography, high voltage electrophoresis, and thin layer chromatography were applied, followed by measurement of radio-activity and biological activity. It is concluded that in no reproducible case was either radioactive isotope incorporated into material with the chromatographic and biological properties of oxytocin. Other radioactive products of incubation were detected in hypothalamic cell sap, ribosomes and cell sap, and homogenate. In hypothalamic homogenate incubations, considerable degradation of both oxytocin and other material absorbing at 280 nm was observed. It is suggested that future investigations should attempt to first develop isolation procedures for the labelled hormone produced in vivo, and then reduce the complexity of the system in small stages, through the cultured hypothalamic-neurohypophyseal system of Sachs3 to simpler in vitro systems. </P> / Thesis / Master of Science (MSc)

<p> The properties of the levels of 21Ne and 29Si have been studied via γ-ray angular distribution and linear polarization measurements and γ-γ coincidence studies yielding a number of new spin-parity assignments to the states of both nuclei. Comparison of the results with the Nilsson model for odd nuclei indicate that for 21Ne, good agreement is in general obtained. Nevertheless, a number of interesting discrepancies exist with regard to the negative parity states of 21Ne and explanations have been proposed for some of these. The agreement is also quite good for 29Si with a calculation using a minimum of free parameters, confirming the oblate shape for this nucleus.</p> / Thesis / Doctor of Philosophy (PhD)