Nuclear Data Sheets for A = 90

Abstract

The 1961 version of Nuclear Data Sheets for A=90and the 1970 Midstream Evaluation, A=90+J. B. Ball, M. W. Johns, and K. Way, Nuclear Data Tables8, 407 (1970)+, have been revised on the basis of experimental data received prior to May 1, 1975. Results from approximately 225 papers and communications chosen from the extensive literature for this A-chain have been included in the present evaluation. Numerous additional references dealing with reaction mechanism studies and nuclear structure theory are not included in this compilation, but are available upon request from the Nuclear Data Project. Data on nine A=90 nuclei are presented. The decay of 90Br has been observed, but the decay scheme has not been established. Recent unpublished results on 90Kr and 90Rb decays are presented. These results are not yet comlete, but appear to be considerably more extensive than previously published work. The particularly simple decay schemes for 90Sr and 90Y are wellk known. A few spin assignments have been proposed for levels in 90Sr, but additional reaction studies would be useful. Many spin assignments have been made for levels in 90Y, 90Zr, 90Nb, and 90Mo from a variety of decay and reaction studies. The results for 90Zr are particularly extensive. The decay schemes for 90Nb and 90Mo appear reasonably well established. Recent results on the decay of two 90Tc isomers are presented, but the decay schemes have not been established and the energy ordering of the two isomers is not known.