Thesis (Ph. D.)--Duke University, 2007. / Includes bibliographical references.

Studying nuclei beyond the proton dripline can provide valuable information on the structure of nuclei at the limits of stability, where the strong nuclear force starts to be overcome by Coulomb repulsion between protons. Simple experimental observables, such as excitation energies and lifetimes of excited states in these proton-unbound nuclei can provide information on the nuclear wave function. Experimental data, such as that presented in this work, can then be used to improve models of nuclear structure at the proton dripline. This thesis presents data from a recoil-decay tagged differential plunger experiment undertaken at the University of Jyvaskyla in 2014. A fusion-evaporation reaction was used to populate excited states in the deformed ground-state proton emitter 113Cs. The JUROGAM-RITU-GREAT experimental setup was used to correlate gamma rays emitted from these excited states with protons emitted from 113Cs and the differential plunger for unbound nuclear states (DPUNS) was placed at the target position to measure the excited state lifetimes. The lifetime of the (11/2+) state in the most intense rotational band of 113Cs was measured to be tau = 24(6) ps, while a limit of tau is less than or equal to 5 ps was found for the lifetime of the higher energy (15/2+) state. The lifetime of proton emission was measured to be tau = 24.2(2) microseconds. The experimental data were used to test the predictions of a non adiabatic quasi-particle model for proton-emitting nuclei, which was employed to deduce the deformation of the states in 113Cs. Wave functions from the non adiabatic quasi-particle model were used to independently calculate proton-emission rates, gamma-ray transition rates and excited state energies as functions of deformation. The deformation of 113Cs could then be extracted from the intersection of the different theoretical values and experimental observables. A deformation of beta2 = 0.22(6)was extracted from the (11/2+) excitation energy and lifetime. The deformation values taken from the proton-emission rate and the lifetime limit of the (15/2+) state were also consistent with this value. The consistency of the different deformations calculated shows the effectiveness of the non adiabatic quasi-particle method when used to calculate the properties of deformed ground-state proton-emitters.

O Laboratório de Metrologia Nuclear (LMN) do Instituto de Pesquisas Energéticas e Nucleares (IPEN) realizou a padronização primária dos radionuclídeos 64Cu e 166Ho. Esses radioisótopos são utilizados na Medicina Nuclear em investigações diagnósticas e em radioterapia. A atividade absoluta foi determinada utilizando o método de coincidências 4πβ(PC)- γ associado à técnica de extrapolação de eficiência. Para isto, foram utilizados um contador proporcional em geometria 4π acoplado ao um contador de cintilação NaI (Tl). Para a padronização do 64Cu foram utilizados dois sistemas para registro de dados: sistema TAC e sistema SCS. No sistema TAC é utilizado o módulo Time to Amplitude Converter (TAC) associado a um analisador multicanal, sendo que a eficiência do detector 4πPC foi variada por meio de absorvedores externos e foi aplicado fator de correção para as eficiências beta denominado fator Kawada. No sistema SCS (Software Coincidence System) o registro dos eventos foi feito por meio da digitalização dos pulsos, a eficiência do detector 4πPC foi variada por discriminação eletrônica e a atividade foi obtida pela extrapolação biparamétrica. A padronização do 166Ho em sistema de coincidências 4πβ(PC)- γ foi realizada utilizando o sistema de aquisição de dados por software, SCS (Software Coincidence System). Para determinação das probabilidade de emissão gama dos radionuclídeos foi utilizado um espectrômetro gama HPGe calibrado com ampolas padrão de 152Eu, 60Co, 133Ba, 137Cs e 241Am, calibradas no sistema primário 4πβ(PC)- γ. A probabilidade de emissão gama por decaimento do fóton de 1345,7 keV do 64Cu obtida foi de 0,472 (10) % apresentando um bom acordo com os dados da literatura. A probabilidade de emissão gama por decaimento do fóton gama de 1379,45 keV do 166Ho foi de 0,936 (4) %. Por meio destas medidas foi possível também a determinação das intensidades relativas de outros fótons emitidos por este radionuclídeo. Os resultados obtidos foram concordantes com a literatura dentro da incerteza experimental. / The procedure followed by the Nuclear Metrology Laboratory (LMN) at the Nuclear and Energy Research Institute (IPEN) for the primary standardization of 64Cu and 166Ho is described. These radionuclides are widely applied to Nuclear Medicine such as in diagnostic investigations and in radiotherapy. The absolute activity of both radionuclides were determined by the efficiency extrapolation method applied to 4πβ(PC)-γ coincidence counting system using a proportional counter in 4π geometry coupled with NaI(Tl) scintillation counter. The primary standardisation of 64Cu for the conventional coincidence counting, the events were registered using a Time to Amplitude Converter (TAC) system associated with a multi-channel analyzer and by a software coincidence counting system, SCS, a digital method for primary activity measurements that simplifies the setting of optimal coincidence parameters. For perfoming the standardization of 64Cu in the TAC system, the efficiency of the 4πβ(PC)-γ detector was varied using external absorbers and in order to correct the beta efficiency, the Kawada factor was applied. In the SCS counting, the events were registered by means of pulse digitalization and the efficiencies (εEC and εβ) were varied through eletronic discrimination. The biparametric method was used for determining the absolute activity and the result was in good agreement with the ones obtained with TAC system. The standardization of 166Ho in the primary system was performed using the software coincidence counting, SCS. The gamma-ray emission probability per decay of the main transitions of both radionuclides were determined using the results obtained from the primary method, the 4πβ(PC)-γ coincidence system, associated with a calibrated HPGe gamma-ray spectrometer with standard ampoules of 152Eu, 60Co, 133Ba, 137Cs e 241Am, previously standardized in the 4πβ(PC)-γ system. The gamma-ray emission probability per decay of the 1345,7 keV transition of 64Cu was 0,472 (10) %, in good agreement with the literature. The gamma-ray emission probability per decay of the 1379,45 keV transition of 166Ho was 0,936 (4) %. It were also determined the relative gamma ray emmission probability of other gamma rays for this nuclide . All the results obtained were in good agreement with the literature.

L'émission gamma des novae à, et en dessous, de 511 keV provient essentiellement de l'annihilation des positrons venant de la décroissance beta+ du 18F. L'interprétation de cette émission, à l'aide d'observations par le satellite INTEGRAL par exemple, nécessite une bonne connaissance de la nucléosynthèse du 18F. Dans ce contexte, le taux de la réaction 18F(p,alpha)15O est le moins bien connu à cause de deux résonances correspondant aux niveaux excités Ex = 6.419 et 6.449 MeV dans le 19Ne dont les largeurs protons sont totalement inconnues. Nous avons déterminé ces largeurs protons par le biais d'une réaction de transfert d'un nucléon D(18F,p alpha)15N peuplant les niveaux analogues, dans le 19F, des niveaux d'intérêt astrophysique. Nous avons utilisé un faisceau radioactif de 18F accéléré à 14 MeV au Centre de Recherche du Cyclotron de Louvain--la--Neuve sur une cible de CD2 en cinématique inverse ainsi que le détecteur multi--piste au silicium LEDA. Une analyse en DWBA a permi de déterminer la largeur proton de ces deux résonances et a montré qu'elles ne pouvaient pas être négligées dans le calcul du taux de réaction. Une étude détaillée des incertitudes restantes sur le taux de réaction a été entreprise et particulièrement en ce qui concerne les interférences entre ces résonances et une autre résonance à plus haute énergie dans le 19Ne. Le taux de réaction ainsi établi diffère peu de l'ancien taux nominal mais repose maintenant sur des bases plus solides permettant une meilleure interprétation des futures observations gamma des novae et donc une meilleure contrainte des modèles astrophysiques.