B. S. Gao

Characteristics of a CsI(Tl) Compton-suppressed clover detector

The performance of a four fold segmented clover detector coupled to a CsI-suppressed shield has been tested using several standard radioactive sources. The summing characteristics, hit patterns and absolute efficiency were measured in both crystal and clover modes. Peak-to-total ratios of 57.3% and 45.6% in suppressed clover mode have been determined for 137Cs and 60Co sources, respectively. A Geant4 simulation of the suppressed clover detector, including the segmentation of the germanium crystals, has been created, and the simulation results agreed very well with the experimental data.

Experiment for synthesis of neutron- deficient protactinium isotopes

The complete fusion reaction 40 Ca+ 175 Lu was studied at a beam energy of 5.1 MeV u �1 . Evaporation residues recoiled from the target were separated from the primary beam by the gas-filled recoil separator SHANS and then implanted into the focal plane detection system. Based on the energy-positiontime correlation measurement, neutron-deficient nuclei − 208 213 Ac, 212 Pa and 211 Th produced in this reaction were identified. Previously reported decay properties of the ground state in 212 Pa were confirmed and improved values of − + 5.1 1.7 ms and 8.250(20) MeV for the half-life and α-particle energy of 212 Pa were obtained. No correlated decay chain arising from 211 Pa was observed and an upper limit for the cross section of 211 Pa was estimated.

High-spin level structure in deformed odd-odd ~(186)Au

High-spin states in deformed odd-odd 186Au have been reinvestigated via the 172Yb(19F,5nγ) fusion-evaporation reaction.Detailed analysis of γ-γ coincidence relationships leads to a revised high-spin level scheme for 186Au.New spin values are assigned to the prolate πh9/2i13/2 and πi13/2i13/2 bands in 186Au according to the level spacing systematics as well as the existing knowledge in odd-odd neighboring nuclei.Based on the new spin assignments,both bands exhibit the characteristics of low-spin signature inversion.The properties of signature splitting for the prolate πh9/2i13/2 and πi13/2i13/2 and oblate πh-111/2νi-131/2 bands in Au isotopes have been discussed.A new rotational band built on Ix=(20+) state has been identified and assigned as the oblate πh-111/2  νi-232h-19/12 configuration.

Properties of the {pi}h{sub 11/2} band in the stable nucleus {sup 193}Ir

Excited states in the stable nucleus {sup 193}Ir have been investigated through an in-beam {gamma}-ray spectroscopic technique following the {sup 192}Os({sup 7}Li, {alpha}2n) reaction at a beam energy of 44 MeV. A level scheme built on the {pi}h{sub 11/2} isomer has been extended to high-spin states using eleven newly observed {gamma} transitions. The {pi}h{sub 11/2} band is proposed to be formed by coupling an h{sub 11/2} proton to a core with large triaxial deformation. Three-quasiparticle states are suggested in {sup 193}Ir on referring to the similar states in {sup 187}Ir. The features of signature splitting in the {pi}h{sub 11/2} bands of {sup 187-193}Ir are discussed with the help of total Routhian surface calculations.