Laser Spectroscopy Of Neutron-Deficient Bismuth Isotopes

This thesis investigates the neutron-deficient isotopes 187,188,189,191Bi. A particular focus was placed on studying their alpha decay and isomeric states. The data analysed was gathered at the ISOLDE facility at CERN. Bi nuclei were produced through the collision of high energy protons with a uranium carbide target. A three-step laser ionisation process was used to extract two states of Bi: the ground state and an isomer. These were separately analysed. After mass
separation, the Bi nuclei were implanted into carbon foils with silicon (Si) detectors used to measure alpha decays and high purity germanium (HPGe) detectors used to measure gamma decays.
The alpha decay schemes of the ground state and the isomeric state of Bi were derived from the Si energy spectra. By doing this, the hyperfine structure (HFS) was established and isotope shifts were deduced. Conclusions drawn from this research will assist in deducing the evolution of deformation of bismuth nuclei. This work is a collaborative extension of the experiments undertaken at Gatchina, Russia, as described in the latest publication by A. Barzakh et al [1].
Gatchina cannot access the lightest isotopes of Bi, hence, the work completed at ISOLDE is paramount in gaining a full understanding of Bi.