The decay schemes of ⁷⁶As, ²⁰⁷Bi and ⁷⁵Se have been studied using Ge(Li) detectors and coincidence techniques with particular emphasis on the weaker modes of gamma decay. The feasibility of detecting weak modes of gamma decay is discussed and supporting electronic systems which have been developed to yield data suitable for reduction and analysis with computer programmes are described. Low energy gamma transitions in the decay of ⁷⁵Se were studied using an X-ray Ge(Li) detector. Two previouslyunconfirmed transitions at 24.4 keV and 80.8 keV have beendetected and their positions in the decay scheme of ⁷⁶As have been established. In the decay of ²⁰⁷Bi, an upper limit of 0.014 +/- 0.008 relative to the 570 keV transition as 100 has been placed on the intensity of the 'l-forbidden' gamma transition at 328 keV. The decay scheme of ⁷⁶As has been shown to include two previously unreported gamma-rays at 220 keV and 316 keV and coincidence experiments have indicated a new energy level at 2006 keV. Several gamma-rays and level energies suggested by previous authors were not confirmed by this work.

Gamma rays following the decay of ¹⁶⁰Tb and ¹⁸⁸W were detected in both singles and coincidence in order to establish the energy level scheme of the two medium mass nuclei ¹⁶⁰Dy and 1880s. Two large volume Ge(Li) detectors together with a plastic scintillation counter were incorporated in a Dual Parameter Energy-Time Spectrometer to measure the gamma-gamma coincidence spectra: the half-life of the first excited state of ¹⁶⁰Dy was measured. An intrinsic Germanium detector was used to measure low energy transitions. New levels and transitions are proposed, relative intensities, log ft values, multipolarities, spins/parities and transition probabilities are deduced. The nuclear properties of ¹⁶⁰Dy and ¹⁸⁸Os are analysed in terms of current nuclear models. The deviations from the predictions of the symmetric rotor model for the states in ¹⁶⁰Dy are explained in terms of band-mixing. The Coriolis coupling is applied to the negative states which gives good account to the electric dipole transition probabilities. The possible effect of the recently discovered sub-shell closure at Z = 64 is investigated for ¹⁶⁰Dy, a nucleus with proton number (Z=66) exactly midway between the closures at 50 and 82, and the number of neutrons (N=94) above the limit of 90. Energy levels, B(E2) absolute values and ratios are compared with IBM-1 calculations assuming either a single Z = 50-82 shell or a subshell closure at Z = 64. The latter calculation improves agreement with experiment. The O(6) limit description is applied to the ¹⁸⁸Os nucleus. Particular attention is made to the 0⁺ states and M1 transitions, the presence of which form the basic test for an 0(6) type nucleus. The calculations in the context of IBM-1 were undertaken with the aid of the computer codes PHINT and FBEM.

The Wolfenstein p-p parameters P, D and R have been measured at the four laboratory scattering angles 6, 9, 15 and 24 degrees together with a single R' measurement at the 15 degree angle. Statistical error on each measurement is typically 0.025. A 518 MeV polarized proton beam was produced at TRIUMF from a Lamb Shift source and free p-p scattering was observed from a liquid hydrogen target. Components of the initial and final polarizations were measured; the former by scintillator telescopes viewing a CH2 target, the latter by a large solid angle acceptance (carbon) Polarimeter utilizing multiwire proportional chambers. A separate experiment was undertaken to calibrate the Polarimeter at 9 energies and the results from the analysis of this data were used in the final calculation of the Wolfenstein parameters. Time-of-flight and momentum analysis were undertaken to remove inelastic protons and pions above threshold. Straight tracks through the final Polarimeter were rejected by beam defining counters for overall efficiency of the experiments. A superconducting solenoid was used in the R and R' measure-ments to precess the vertical primary beam polarization by ± 90 degrees into the horizontal plane before the hydrogen target. The polarization of the primary beam was reversed at its source for the four parameter's measurements allowing data to be recorded for two polarization orientations. The R' parameter required a precession magnet in the secondary beamline to precess the longitudinal polarization into the horizontal plane. The measured Wolfenstein parameters have been used in asingle energy phase shift analysis at 515 MeV to improve the precision of the isovector nucleon-nucleon phases.

The states populated in the beta decay of As⁷⁶ and Ga⁷² were investigated by measuring the gamma-ray transitions in Se⁷⁶ and Ge⁷² using 25cc., 33cc. and 60cc. true-coaxial Gs(Li) detectors. A dual-parameter data collection system was constructed to study gamma-gamma coincidence. Options were provided to enable corrections of the undesired contributions from Compton background and chance coincidences. Its performance was shown to be very reliable and effective. Coincidence experiments were performed with the 25cc. and 33cc. Ge(Li) detectors using the conventional fast-slow system in the case of As⁷⁶ and the dual-parameter system was used in coincidence work on Ga⁷² employing the 33cc. and 60cc. detectors. The energies and intensities of measured gamma-rays were determined. The level schemes were constructed and the log ft and parity were deduced. The collective aspects of certain states were discussed and some comparisons with the pure vibrational and two other collective models were attempted.

We present a computer program tailored to the calculation of single particle inclusive reaction observables and two models for the incorporation of absorptive type corrections in the triple Regge region which do not require the inclusion of free parameters. We conclude that the first model we present is not sufficiently realistic and so requires the derivation of the second, more sophisticated model in the Regge-eikonal approximation. Both models were used to examine the observables for pseudo-scalar meson production via charge exchange.

<p> Space radiation exposure to astronauts will need to be carefully monitored on future missions beyond low earth orbit. NASA has proposed an updated radiation risk framework that takes into account a significant amount of radiobiological and heavy ion track structure information. These models require active radiation detection systems to measure the energy and ion charge Z. </p><p> However, current radiation detection systems cannot meet these demands. The aim of this study was to investigate several topics that will help next generation detection systems meet the NASA objectives. Specifically, this work investigates the required spatial resolution to avoid coincident events in a detector, the effects of energy straggling and conversion of dose from silicon to water, and methods for ion identification (Z) using machine learning. </p><p> The main results of this dissertation are as follows: 1. Spatial resolution on the order of 0.1 cm is required for active space radiation detectors to have high confidence in identifying individual particles, i.e., to eliminate coincident events. 2. Energy resolution of a detector system will be limited by energy straggling effects and the conversion of dose in silicon to dose in biological tissue (water). 3. Machine learning methods show strong promise for identification of ion charge (Z) with simple detector designs.</p><p>

Non-spherical components of the nucleon wave function are measured through p(e,e'p)π experiment at the Δ+(1232) resonance for Q2 = 0.04, 0.09, and 0.13 (GeV/c)2 utilizing the Jefferson National Accelerator Facility (JLab) pulsed beam and Hall A spectrometers. The new data extend the measurements of the Coulomb quadrupole amplitude to the lowest momentum transfer ever reached. The results disagree with predictions of constituent quark models and are in reasonable agreement with dynamical calculations that include pion cloud effects, chiral effective field theory and lattice calculations. The reported measurements indicate that improvement is required to the theoretical calculations and provide valuable input that will allow their refinements. The Coulomb to magnetic multipole ratio (CMR) and generalized polarizability (GP) of the nucleon are also measured through virtual Compton scattering (VCS) for Q² = 0.2 (GeV/c)2 utilizing the Mainz Microtron (MAMI) continuous beam and A1 spectrometers. This data represents the first low Q² GP measurement at the Δ+(1232) resonance. The GP measurement explores a region where previous data and theoretical calculations disagree. The CMR measurement will be the first VCS extraction to compare with world data generated through pion electroproduction. The Dispersion Relation (DR) model used for the VCS extraction provides a new theoretical framework for the data signal and backgrounds that is largely independent from the pion electroproduction models. The independence of the DR from the traditional models provides a strong crosscheck on the ability of the models to isolate the data signal. / Physics

<p>A new external microprobe beamline for irradiation experiments has been commissioned and constructed at the Louisiana Accelerator Center. This microprobe was designed to use the Oxford Triplet lens con?guration with no scanning system. The beamline was designed to allow for the post focus expansion of the ion beam to create an even ?led of current distribution at a sample. The samples are irradiated in air in a glove box so that a Biosaftey-Level 2 (BSL-2) environment is created, reducing risk of contamination for biological sample irradiation. The nature of a microprobe allows the ?ux, and therefore the dose, to be su?ciently low for space radiation studies. The beamline was designed using WinTRAX [18] and constriction has been completed. This thesis is an overview of what a microprobe is, how the new microprobe was designed, and how the beamline was constricted.

<p>This thesis presents the design and simulation of a multi-channel integrated circuit (IC) that will be used in nuclear physics experiments. The chip is being designed as a companion chip for another IC used in particle identification called PSD8C. The IC described in this thesis is used to create precise timing pulses for starting time-to-voltage converters (TVCs) and gated integrators on the PSD8C. These timing pulses are created using a technique called Constant Fraction Discrimination (CFD). Each of the sixteen channels in the IC contains a Nowlin circuit, leading-edge discriminator, zero-cross discriminator, and a one-shot circuit to generate the output. The IC will support input pulse amplitudes between 15 mV and 1.5 V (both positive and negative), and input pulse rise times between 2 nsec and 192 nsec. The IC will feature a programmable output pulse width between 50 nsec and 500 nsec. The IC will have an average power dissipation of 220 mW and occupy an area of 2.4 x 3.5 mm. The variation (due to process and mismatch) in the trailing edge of the output timing pulse will be less than 5 nsec (for pulse width of 50 nsec). The assosciated jitter the output timing pulse is ?20 psec (for the 50 nsec pulse width mode). Most importantly the output pulse firing time variation will be independent of the input amplitude, having a time walk of only 500 psec or less (for input pulse rise time constants of 2 nsec). The IC has been named CFD16C and the design presented is implemented in a 0.35 micron NWELL process.

<p> Oscillating single neutron stars are considered to be important quasi-continuous sources for gravitational wave emission and detection at the Laser Interferometer Gravitational-Wave Observatory (LIGO). In order to detect these oscillations above the noise level in the detector, LIGO data must be compared to theoretical templates of the signal, which means predicting the signal amplitude and frequency range. In this thesis, we compute the two most important eigenfrequencies of superfluid neutron stars where the signal might be peaked. To calculate this spectrum, we first construct the background structure of the neutron star using realistic microscopic models of dense and interacting nuclear matter. For this purpose, we use the CompOSE database which provides an array of such models with thermodynamically consistent interpolation. The fluid pertubation equations of the equilibrium configuration, including superfluidity in a two-fluid model, are solved numerically in the non-relativistic limit, yielding the eigenfrequencies upon imposing suitable boundary conditions. We find that the modes of the superfluid star support modes that are very close to the corresponding normal fluid star, but there also appear one or two purely superfluid modes, the lower one of which is intermediate between the two lowest order modes of the normal fluid. Thus, in the event that these oscillation modes can be observed, we can confirm the theoretical prediction of neutron superfluidity in neutron stars. A part of the results presented in this thesis have been published as a proceedings article in Jaikumar, Monroy and Klaehn, <i> Universe</i> 4, 58 (2018).</p><p>