M. Shmid

A Four-detector System For γ - γ Angular Correlation Studies

Abstract A multiple detector system for γ - γ coincidence and angular correlation measurements is described. The system consists of four large coaxial Ge detectors set at fixed positions, enabling the measurement of γ - γ coincidences between any pair. Thus, six distinct angles are measured simultaneously. The performance of the system was studied with a 152 Eu source. An application for γ - γ correlation studies in 146 Ce is described. Systematic errors, if present, are shown to be less than 0.03 and 0.05 for A 2 and A 4 , respectively. The extension of this system to more than four detectors is straightforward.

Comparison between solid graphite and graphite cloth as a target backing material for an Isol system

Abstract A high temperature target-ion source system developed for the TRISTAN on-line isotope separator at Brookhaven National Laboratory is described. The system consists of a surface ionization chamber with a Re surface and 235U in a graphite target matrix. Both solid graphite and graphite cloth targets were tested. The overall separation efficiencies for isotopes of Rb, Cs, Sr, Ba, In, Ce,Pr, Nd and Pm which were extracted directly from the ion source were measured. Production rates were measured as a function of temperature up to 2000°C and the ion source performance was monitored over long periods of time. The performance of solid graphite targets was found to give superior stable operation with no deterioration in production rates for operation times of up to 2000 h. In contrast, graphite cloth targets exhibited deterioration in efficiency with time for most elements with differing rates. The production rates of Ce and Pr isotopes increases significantly during the first 400 h of operation, followed by a slow decrease.

Parabolic energy dependence of odd-odd multiplets in N=83 nuclides

The splitting and the displacement of low-lying πg72νf72 and πd52νf72 multiplets in the odd-odd N = 83 isotones are found to be described by a quadrupole interaction between the odd proton and odd neutron. The quenching and inversion of the πd52νf72 parabola is found to arise from the quasiparticle blocking effect as the occupancy of the d52 orbital changes.