Experimental studies of nuclides far from stability with the TRISTAN II fission-product separator at the Brookhaven National Laboratory (Yrast bands; delayed-neutron spectra). Final report, January 1, 1980-November 30, 1982

The research program under this contract consisted of two projects; one was the study of yrast bands and the other the study of energy spectra of beta-delayed neutrons. Both utilized the TRISTAN mass separaotr at Brookhaven National Laboratory. The nuclides of interest for the yrast band project were ot produced at TRISTAN during the period of the contract, so effort was limited to planning and to presentation of papers. The neutron project required the design, construction, testing, and calibration of apparatus that is not commercially available. Neutron detectors were later made available onloan. The time-of-flight method was used, beta and neutron signals from scintillators detectors providing start and stop signals. He-3 gas and Li-6 glass scintillators were used for neutrons, plastic for betas. The best timing resolution was 2.7 nsec FWHM; including geometrical contributions,neutron FWHM energy resolution as good as 2.7% at 14 keV was obtained at 50 cm flight path. This is sufficient to deduce the natural line width of the 14 keV resonance in Sr-95. Background neutrons and gamma rays limit the system sensitivity at present, but improvements appear feasible that will permit deduction of leveldensities and in some cases widths of a number of neutron-rich nuclides that are inaccessible to study by any other probe. The data bear on optical models and neutron cross sections for such nuclides