No abstract

Lifetimes of low-lying levels in 57 Ni have been investigated using the reaction 54 Fe(a, ») 57 Ni and the Doppler-shift attenuation method. The lifetimes are not in agreement with single-particle predictions and, together with the presence of new low-lying levels in 57 Ni, confirm the presence of core excitation of 56 Ni.

W'e have experimentally located a polarization extremum (A"= -1) in triton~elastic scattering near Et = 11.1 MeV,~c.m. = 95 . This is the first application and test of a Lamb-shift polarized tritium ion source which has been installed on the Los Alamos tandem accelerator. The results verify the accuracy of the quench-ratio method for the determination of the polarization of the triton beam.NUCLEAR REACTIONS He(t, t); E, =10.2 -11.7 MeV, measured A (0). Demonstrated existence of A, =-1 point.

The 0.76-, 1.70-, 2.32-, 2.79-, and 3.54-MeV levels of Si 31 have been studied using a collinear geometry with the observed particles being detected in an annular solid-state counter placed at 180° relative to the beam direction. The above levels were populated by the Si 30 (d,/>)Si 31 reaction with deuteron energies of 3.01 and 3.22 MeV. 7 radiation was detected by a 7.62X7.62-cm Nal crystal at five angles between 26° and 90° relative to the beam direction. From the analysis of the experimental correlations, spin determinations of f, f, J, and f were established for the 1.70-, 2.32-, 3.14-, and 3.54-MeV levels, respectively. An isotropic correlation was measured for the level at 760 keV, in agreement with the known spin of | for this level. The analysis for the 2.79-MeV level agrees with the spin value of f which is indicated from the shape of the l n~2 angular distribution from the Si 30 (d,p) reaction corresponding to population of this level. In addition, information on the 7-ray multipole mixing ratios and 7-ray branching ratios for many of the above levels was determined.