New β-decay half-lives of heavy neutron-rich nuclei and performance studies of the GEM-TPC detector

This thesis presents results from the experiments aimed to measure new b-decay half-lives of neutron-rich nuclei near the N = 126 shell and investigate the performance of the GEM-TPC detector. Experimental requirements for the b-decay experiment included production, identification, and analysis of properties of heavy neutron-rich nuclei. In total, one experiment and two in-beam tests were conducted at the FAIR/GSI facility. Four new b-decay half-lives for isotopes ^197-198Re, ¹⁹⁵W, and ¹⁹¹Ta were measured. Additionally, the measured half-life values for ^199-200Os and ¹⁹⁶Re were consistent with literature values. Detailed analyses of the experiment and in-beam tests are presented, including a comparison with measured b-decay half-lives and predicted values from the FRDM + QRPA and CQRPA models. Consistently shorter half-life values than predictions were observed for nuclei near N = 126 shell. The performance analysis of the GEM-TPC detector provided information on its properties, such as x position resolution, y position resolution, cluster strip multiplicity, control sum, detection and tracking efficiencies, strip signal summation, and data digitization impact. Moreover, a clusterization was utilized for the first time in the data analysis of the GEM-TPC detector. The objectives of the studies were to increase our understanding about the properties of nuclei in the vicinity of the third r-process peak and to measure the capabilities of the GEM-TPC. The experimental results of the new b-decay halflives can be used to validate existing models and improve our understanding of the properties of these nuclei. The performance study of GEM-TPC provides information on its measuring capabilities and suitability for future investigations and assists in planning the future experiments.