Nuclear Data Sheets for A = 84

Abstract

The evaluated spectroscopic data are presented for 12 known nuclides of mass 84 (Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo). Except for the stable nuclides84Sr and84Kr, extensive new data are available for all the other nuclides since the 1997 evaluation by J.K. Tuli (1997Tu02) of A = 84 nuclides. Many precise Penning-trap mass measurements since AME-2003 for A = 84 nuclides (2009Re03,2008Ha23,2008We10,2007Ke09,2006Ka48,2006De36,2006Ri15) have resulted in improved Q values and separation energies. However, many deficiencies still remain. Some examples are given below. Excited-state data for84Ga and84As are nonexistent, and those for84Ge are scarce. The radioactive decay schemes of84Ga,84Ge,84Se,84Y (39.5 min),84Y (4.6 s),84Zr and84Nb suffer from incompleteness and that for84Mo decay is not known at all. The energy ordering of the two activities (39.5 min and and 4.6 s) of84Y is not well established, although, high-spin with tentative spin-parity of (6+) is adopted here as the ground state of84Y based on weak arguments. From a conference report published in 2000, it is clear that extensive experiments were done to investigate decays of84Zr and84Y, but details of these studies never appeared in literature and none were made available to the evaluators when requested from original authors. This evaluation was carried out as part of ENSDF workshop for Nuclear Structure and Decay Data Evaluators, organized and hosted by the "Horia Hulubei" National Institute for Physics and Nuclear Engineering, Bucharest, Romania during March 30, 2009 - April 3, 2009. Names of the evaluators principally responsible for evaluation of individual nuclides are given under the respective Adopted data sets.