Study of the development of shell closures at N = 32,34 and approaches to sub-segment interaction-point determination in 32-fold segmented high-purity germanium detectors

The even 52--56Ti isotopes have been studied with intermediate-energy Coulomb excitation and absolute B(E2; 0 + → 2+1 ) transition rates have been deduced. Our data confirm the presence of a sub-shell closure at neutron number N = 32 in neutron-rich titanium isotopes above the doubly-magic nucleus 48Ca and provide no direct evidence for the predicted N = 34 closure. Large-scale shell model calculations with the most recent effective interactions are unable to reproduce the magnitude of the measured strengths in the semi-magic Ti isotopes and their strong variation with neutron number.;Sub-segment position resolution of the gamma-ray interaction points has been demonstrated for the cylindrically-symmetric 32-fold segmented HPGe detectors of the NSCL/MSU Segmented Germanium detector Array (SeGA) using digital electronics. Waveforms of the real charge signals from segments that contain interaction points and induced charge signals from neighboring segments were digitally recorded by 100 MHz ADCs. Simple integrated quantities (amplitudes, areas, peak times) were extracted from the waveforms. By analyzing the asymmetry of the induced signals we could determine the proximity of the interaction point to segments without net-charge deposition, attaining sub-segment position resolution along the crystals symmetry axis. The radial position of the interaction point was determined through an analysis of the rise times of the real charge signals. Although less precise than other methods involving a complete waveform analysis, the use of integrated quantities simplifies the problem of sub-segment interaction position estimation.