Multinucleon-Transfer Reactions as a Gateway to Neutron-Rich Actinides and Nuclei near the N=82 and Z=50 Shell Closures

In the present work, reaction products in the 136Xe+238U multinucleon-transfer reaction at 1 GeV were investigated employing the high-resolution position-sensitive gamma-ray tracking array AGATA coupled to the large-solid-angle mass spectrometer PRISMA at the Laboratori Nazionali di Legnaro (INFN, Italy). Beam-like reaction products were identified and selected by the PRISMA spectrometer. Recoils and fission fragments were tagged by DANTE micro-channel plate detectors installed within the scattering chamber. Fission and transfer events are discriminated by exploiting kinematic coincidences between the binary reaction products. Mass yields and relative cross-section distributions are extracted and compared with calculations based on the GRAZING model for multinucleon-transfer reactions. Furthermore, population yields for nuclei in the actinide region are obtained and compared to X-ray yields measured by AGATA. Perspectives and limitations for the production of the hard-to-reach neutron-rich isotopes are discussed. A Doppler correction for the target-like nuclei enables gamma-ray spectroscopy of the heavy reaction partner. Nuclear structure information of neutron-rich actinide nuclei are a benchmark for theoretical models providing predictions for the heaviest nuclei. An extension of the ground-state rotational band in 240U is achieved and evidence for an extended first negative-parity band in 240U is found. The results are compared to recent mean-field and density-functional theory calculations. Furthermore, multinucleon-transfer reactions are a gateway to nuclei in the vicinity of the Z=50 and N=82 shell closures. Nuclei in this region serve as a benchmark for nuclear shell-model calculations based on modern effective interactions, but are difficult to populate due to a lack of suitable beam-target combinations. Excited reaction products were measured after multinucleon transfer in 136Xe+238U at 1 GeV and 136Xe+208Pb at 930 MeV with the AGATA tracking array coupled to PRISMA at LNL (INFN, Italy) as well as in the 136Xe + 198Pt multinucleon-transfer reaction employing the high-efficiency gamma-ray spectrometer GAMMASPHERE in combination with the gas-detector array CHICO at LBNL. Moreover, Xe and Ba isotopes were populated in fusion-evaporation reactions using the HORUS gamma-ray array at the University of Cologne. The high-spin level schemes of 132Xe, 133Xe, 134Xe, 135Xe and 137Ba were considerably extended to higher energies. The 2058-keV state in 135Xe is identified as a 9.0(9)-ns isomer, closing a gap in the systematics along the N=81 isotones. Latest shell-model calculations reproduce the experimental findings. The experimentally-deduced reduced transition strengths of the isomer decays are compared to shell-model predictions. A detailed picture of the lower-mass N50 region of the Segrè chart is drawn. Another part of this thesis covers double-sided silicon strip detectors (DSSSD) which are employed for the detection of charged particles providing position and energy information. Intersecting areas of both p- and n-side strips form individual pixel segments resulting in a high detector granularity. However, due to limitations in fabrication and the response of the readout electronics, the performance of different channels may vary. Typically, charged particles do not illuminate homogeneously the detector surface during in-beam experiments. Consequently, radiation damages of the detector are distributed non-uniformly. Position-resolved charge-collection losses for front- and back-side segments were investigated for an in-beam experiment and by performing radioactive source measurements. A novel position-resolved calibration method for radiation-damaged DSSSDs, based on mutual consistency of p-side and n-side charges, was developed. It yields a significant enhancement of the energy resolution and the performance of radiation-damaged parts of the detector