<div> We consider the existence of a force that could produce a non-null result in the Eötvös experiment while producing a null result in the Eöt-Wash experiment. We introduce a general force, in the form of its Taylor series expansion, and determine the response of each experiment to that force. We can then determine which terms of the expansion are important to each experiment. A trial force, in the form of a mixed vector-scalar interaction is introduced and we analyze the resulting Eötvös parameters for various values of the strengths and ranges of the interactions. We find that under certain conditions the Eötvös parameter for the Eöt-Wash experiment can be made zero while the Eötvös parameter for the Eötvös experiment is nonzero.</div><div> </div><div><br></div><div> Next, we examine the possibility of a wind force appearing in the MICROSCOPE experiment. This wind would be due to the satellite's motion through a particle background which couples to the differential accelerometer through a baryon-number dependent interaction. We determine the signal that would be measured by MICROSCOPE satellite and compare the power spectrum density of this signal to the published power spectrum density of the experiment. </div><div> </div><div><br></div><div> Additionally, we present a new theoretical framework for the time-variation of nuclear decay rates. This new framework is motivated by the results of numerous experiments which show a periodicity of one year. The fractional decay rate of these experiments are constant, regardless of isotope. We find that a novel neutrino interaction, in the form of an index of refraction, successfully generates the constant fractional decay rates. Using the optical theorem and the relativistic Breit-Wigner distribution makes the index of refraction consistent with neutrino speed measurements. We conclude by describing other systems where the index of refraction could create observable oscillations.</div><div><br></div><div> </div><div> Finally, we consider the suppression of beta decay rates through the Pauli exclusion principle due to the presence of background cosmic and solar neutrinos. We derive the suppression factor for both thermalized and non-thermalized neutrinos.</div>

Neste trabalho são apresentados resultados experimentais referentes ao decaimento beta do Nb POT.92, obtidos a partir de medidas da atividade gama residual que segue a reação Nb POT.93 (gamma, n). A alimentação do nível a 2067 keV do Zr POT.92 foi determinada com boa precisão. A não observação de transições gama que envolvem os níveis 0 POT.+ e 4 POT.+ do Zr POT.92 permitiram, a partir de uma analise estatística rigorosa determinar-se limites superiores para a alimentação desses níveis. Os resultados experimentais obtidos, bem como diversos outros disponíveis na bibliografia especializada, foram analisados a luz do modelo de camadas, explorando-se especialmente a contribuição do orbital de nêutrons g IND.7/2 nos primeiros níveis excitados do Zr POT.92. Os cálculos foram feitos usando-se valores publicados para os elementos de matriz da interação residual próton-próton e supondo-se uma interação delta superficial para a interação nêutron-nêutron. / We have investigated the beta decay of Nb POT.92 measuring the residual gamma activities associated with the Nb POT.93 (gamma, n) reaction. The beta branch to the 2067 keV Zr POT.92 level has been determined. Unobserved gamma-rays, with a rigorous statistical analysis, allow the determination of upper limits to beta transitions to the 0 POT.+ and 4 POT.+ levels of Zr POT.92. We have compared ours and other published results with the predictions of shells model, exploring the g IND.7/2 neutron orbit contribution to the levels of Zr POT.92 The shell model calculations have been made using published values for the proton-proton matrix elements. The neutron-neutron matrix elements have been determined assuming a surface delta interaction.

Early in the history of the field of nuclear science, experiments were performed to ascertain whether the half-lives of the radioactive substances being studied – isotopes then called the “radium emanation” [222Rn], “radium A” [218Po], “radium B” [214Pb], and “radium C” [214Bi] - were dependent upon any external factors. At that time, the external factors deemed most likely to affect half-life were temperature and pressure. After several experiments, designed to pick up any change in half-life in the course of changing temperature or pressure, had failed to find any significant changes, it was concluded that half-life does not depend on the physical properties of external environment. And that was the state of the field for a long time - for almost 100 years, in fact. Fairly recently, however, half-life measurements were recorded, and published, that seemed to show a change in half-life at the few percent level for certain radioactive nuclides which were exposed to extremes of temperature - thus challenging the long-held belief in the unchangeability of half-lives. In addition to half-life changes caused by temperature change, other experiments seemed to find half-life changes caused by other external influences, including the chemical environment of the decaying radioactive nuclide, and even the distance between Earth and the Sun at the time of the half-life measurement. In this study we present evidence that the initial beliefs in the immutability of radioactive half-life (with the exception of a few nuclides decaying by electron capture whose orbital electrons are involved in both the decay and also in the chemical bonding of those nuclides) is indeed correct; we have done this by performing precise half-life measurements on the β− emitter 198Au, the EC emitter 97Ru, and on the β− emitter 198Au when sited in gold(III) oxide, Au2O3, (an insulator for practical purposes). We have performed various experiments designed to detect any half-life change at the level of a few parts in 10^4 due to change in temperature, physical environment, or the Earth-Sun distance. In these experiments, we have found no significant half-life change due to any of these external factors. These results represent the most accurate demonstrations of the immutability of radioactive half-life change ever made.

The third and final phase of the Sudbury Neutrino Observatory (SNO) experiment utilized a series of 3He proportional counters called Neutral Current Detectors (NCDs) to detect the neutrons produced by the neutral current interactions of solar neutrinos in the detector. The number of neutrons detected by the NCDs, and hence the total flux of 8B solar neutrinos, has been determined using two novel signal extraction techniques which were designed to be robust against potential unexpected behaviour in the NCD background. These techniques yield total 8B solar neutrino flux measurements of 5.04(+0.42-0.40(stat))(+/-0.28(syst))x10E6/cm2/s and (4.40 - 6.43)x10E6/cm2/s, which are in good agreement with previous SNO results and with solar model predictions, and which confirm that previous NCD analyses were not unduly affected by unexpected background behaviour. The majority of the hardware from the now-completed SNO experiment will be reused to create a new liquid scintillator based neutrino experiment called SNO+. An important part of the SNO+ physics program will be a search for neutrinoless double beta decay, carried out by dissolving 150Nd into the scintillator. The sensitivity of the SNO+ experiment to neutrinoless double beta decay has been evaluated. If loaded at 0.1% (w/w) with natural neodymium, after 1 kTa of data taking SNO+ would have a 90%C.L. sensitivity equivalent to a neutrinoless double beta decay half life of 8.0x10E24a or better 50% of the time; if the experiment were run with neodymium enriched to 50% in 150Nd this limit improves to 57x10E24a. Under a reasonable choice for the 150Nd neutrinoless double beta decay matrix element, these half lives correspond to upper limits on the effective Majorana neutrino mass of 112 meV and 42 meV, respectively. These limits are competitive with those expected from all other near-term neutrinoless double beta decay experiments. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-09-10 21:07:00.25

No description available.

Η μελέτη της διπλής διάσπασης βήτα έχει πρωτεύουσα σπουδαιότητα για τη φυσική των νετρίνων. Θεωρείται ως ο καλύτερος τρόπος για να εξεταστεί ο θεμελιώδης χαρακτήρας των νετρίνων και να καθοριστεί η μάζα τους. Από πειραματικής πλευράς περίπου εννέα διαφορετικού τύπου ισότοπα χρησιμοποιούνται στα πειράματα. Μετά από μια γενική εισαγωγή ακολουθεί μια σύντομη συζήτηση σχετικά με τη φυσική των νετρίνων και της παρουσίας τους στις β διασπάσεις. Η πειραματική προσέγγιση, οι δυσκολίες που αντιμετωπίζουμε καθώς και η τρέχουσα πειραματική κατάσταση στις διπλές βήτα διασπάσεις συζητιούνται, ακολουθούμενες από μια σύντομη συζήτηση των ιδεών και των προτάσεων των μελλοντικών πειραμάτων που σχεδιάζονται. / Double beta decay research has a major role in neutrino physics. It is considered the best way to examine the nature of neutrinos and to determine their mass. From an experimental point of view, nine different isotopes are being used in the experiments. After a general introduction, a brief discussion about neutrino physics and their role in beta decays will follow. The experimental approach, the difficulties that we face and the current double beta decay experiments will be discussed, followed by another summary of the ideas and the proposals of the future experiments.

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Neste trabalho são apresentados resultados experimentais referentes ao decaimento beta do Nb POT.92, obtidos a partir de medidas da atividade gama residual que segue a reação Nb POT.93 (gamma, n). A alimentação do nível a 2067 keV do Zr POT.92 foi determinada com boa precisão. A não observação de transições gama que envolvem os níveis 0 POT.+ e 4 POT.+ do Zr POT.92 permitiram, a partir de uma analise estatística rigorosa determinar-se limites superiores para a alimentação desses níveis. Os resultados experimentais obtidos, bem como diversos outros disponíveis na bibliografia especializada, foram analisados a luz do modelo de camadas, explorando-se especialmente a contribuição do orbital de nêutrons g IND.7/2 nos primeiros níveis excitados do Zr POT.92. Os cálculos foram feitos usando-se valores publicados para os elementos de matriz da interação residual próton-próton e supondo-se uma interação delta superficial para a interação nêutron-nêutron. / We have investigated the beta decay of Nb POT.92 measuring the residual gamma activities associated with the Nb POT.93 (gamma, n) reaction. The beta branch to the 2067 keV Zr POT.92 level has been determined. Unobserved gamma-rays, with a rigorous statistical analysis, allow the determination of upper limits to beta transitions to the 0 POT.+ and 4 POT.+ levels of Zr POT.92. We have compared ours and other published results with the predictions of shells model, exploring the g IND.7/2 neutron orbit contribution to the levels of Zr POT.92 The shell model calculations have been made using published values for the proton-proton matrix elements. The neutron-neutron matrix elements have been determined assuming a surface delta interaction.

The beta+-decay half-lives of the neutron-deficient, odd-odd, N = Z nuclei, 74Rb, 78Y, 82NB and 86Tc were measured following the fragmentation of a primary 92Mo beam at an energy of 60 MeV per nucleon at the GANIL laboratory, France. They were measured by correlating beta+-decays with the implantation of unambiguously identified fragments. The deduced log10 ft1/2-values are consistent with 0+&rarr; 0+, Fermi superallowed transitions, which together with the measured beta+-detection efficiencies suggest T = 1, 1pi- 0+ ground states for these odd-odd, N = Z nuclei. These data represent the heaviest N = Z systems for which Fermi superallowed decays have been established. The results suggest that these nuclei can be used to extend the mass range used to test the Conserved Vector Current hypothesis of the standard model. In addition, an experiment using the reaction 58Ni + 28Si at a beam energy of 200 MeV was performed at the Laboratorio Nationale di Legnaro, Italy, using the EUROBALL spectrometer together with a charged particle silicon detector ball and an array of liquid scintillator neutron detectors. The measured values of the energies of the evaporated, charged-particles and those of the gamma-ray multiplicity (deduced using the liquid scintillator detectors), are used to implement a novel technique for the channel selection of weakly populated evaporation channels.