Badanie struktury kolektywnej w izotopach wapnia metodą wzbudzeń kulombowskich

Niniejsza praca jest poświęcona badaniu struktury superzdeformowanej w jądrze 42Ca. W pracy przedstawiono dwa komplementarne eksperymenty: wzbudzenia kulombowskiego jądra 42Ca, przeprowadzonego z wykorzystaniem układu AGATA+DANTE w INFN Laboratori Nazionali di Legnaro we Włoszech, oraz reakcji fuzji-ewaporacji 32S+12C, przeprowadzonej przy użyciu spektrometru promieniowania gamma EAGLE w Środowiskowym Laboratorium Ciężkich Jonów UW. Zaprezentowano wyniki analizy obu pomiarów. Wyznaczono bogaty zestaw zredukowanych elementów macierzowych przejść typu E2 opisujących strukturę elektromagnetyczną niskoleżących stanów wzbudzonych w izotopie 42Ca, z którego metodą nieważonych energetycznie kwadrupolowych reguł sum obliczono parametry deformacji tego jądra w~stanach 01+, 21+, 41+, 02+ oraz 22+. Po raz pierwszy opisano superdeformację stanów w paśmie bocznym. Wyniki zestawiono z przewidywaniami obliczeń na gruncie modelu powłokowego.This thesis is focused on investigation of the superdeformed structure in 42Ca. Two complementary experiments have been presented: Coulomb excitation of 42Ca performed using the AGATA+DANTE setup at the INFN Laboratori Nazionali di Legnaro, Italy, as well as the 32S+12C fusion-evaporation measurement carried out with the EAGLE gamma-ray spectrometer at the Heavy Ion Laboratory, University of Warsaw. Results from both measurements are shown. A rich set of reduced E2 matrix elements was determined, describing electromagnetic properties of low-lying states in 42Ca. Shape parameters for the 01+, 21+, 41+, 02+ and 22+ states in 42Ca were extracted using the non-energy-weighted quadrupole sum rules method. The superdeformed character of states in the side band has been described for the first time. The results are compared with the predictions of modern shell model calculations

Revised spin values of the 991 keV and 1599 keV levels in 140Sm

The previously accepted spin values of the 991 and 1599 keV levels in Sm140 have been revised and established as 2+ and 0(+), respectively. The γ−γ angular correlation method was used to determine the new spin values. The excited low-spin levels in Sm140 were populated in the Eu140→140Sm and Gd140→ Eu140→140Sm decays. The Gd140 and Eu140 nuclei were produced in the Cd112+S32 reaction at a beam energy of 155 MeV. © 2015 American Physical Societ

Spectroscopy of low-lying states in 140Sm

Electromagnetic transition strengths and spectroscopic quadrupole moments for 140Sm were measured by means of multi-step Coulomb excitation with radioactive beam at the ISOLDE facility at CERN. A complementary experiment was performed at the Heavy Ion Laboratory in Warsaw to assign spins for non-yrast states using the angular correlation technique. Based on the new experimental data previous spin assignments need to be revised

Shape coexistence in 94Zr studied via Coulomb excitation

In recent years, a number of both theoretical and experimental investigations have been performed focusing on the zirconium isotopic chain. In particular, state-of-the-art Monte Carlo shell-model calculations predict shape coexistence in these isotopes. In this context, the 94Zr nucleus, which is believed to possess a nearly spherical ground state, is particularly interesting since the purported deformed structure is basedon the low-lying 02+ state, making it amenable for detailed study. In order to provide definitive conclusionson the shapes of the low-lying states, two complementary experiments to study 94Zr by means of low-energy Coulomb excitation were performed. This data will allow the quadrupole moments of the 21,2+ levels to be extracted as well as for the deformation parameters of the 01,2+ states to be determined and, thus, definitive conclusions to be drawn on the role of shape coexistence in this nucleus for the first time. The first experiment was performed at the INFN Legnaro National Laboratory with the GALILEO-SPIDER setup, which, for the first time, was coupled with 6 lanthanum bromide scintillators (LaBr3:Ce) in order to maximize the γ-ray detection effciency. The second experiment was performed at the Maier-Leibnitz Laboratory (MLL) in Munich and used a Q3D magnetic spectrograph to detect the scattered 12C ions following Coulomb excitation of 94Zr targets

Shape coexistence in

In recent years, a number of both theoretical and experimental investigations have been performed focusing on the zirconium isotopic chain. In particular, state-of-the-art Monte Carlo shell-model calculations predict shape coexistence in these isotopes. In this context, the 94Zr nucleus, which is believed to possess a nearly spherical ground state, is particularly interesting since the purported deformed structure is basedon the low-lying 02+ state, making it amenable for detailed study. In order to provide definitive conclusionson the shapes of the low-lying states, two complementary experiments to study 94Zr by means of low-energy Coulomb excitation were performed. This data will allow the quadrupole moments of the 21,2+ levels to be extracted as well as for the deformation parameters of the 01,2+ states to be determined and, thus, definitive conclusions to be drawn on the role of shape coexistence in this nucleus for the first time. The first experiment was performed at the INFN Legnaro National Laboratory with the GALILEO-SPIDER setup, which, for the first time, was coupled with 6 lanthanum bromide scintillators (LaBr3:Ce) in order to maximize the γ-ray detection effciency. The second experiment was performed at the Maier-Leibnitz Laboratory (MLL) in Munich and used a Q3D magnetic spectrograph to detect the scattered 12C ions following Coulomb excitation of 94Zr targets