Delayed-neutron emission probabilities (P") were measured for 16 isotopes of Br, Rb, I, and Cs. Sources of chemically and mass separated nuclides were obtained from an on-line mass spectrometer facility. Neutrons were counted in a multitube polyethylene-moderated detector. The total number of precursor atoms was determined by direct counting of ions deposited on the first dynode of an electron multiplier. The P"values from this work generally agree with earlier measurements for the longer-lived precursors but are consistently higher for the shorter-lived precursors. A log-log plot of P"versus the reduced energy window (Q& -B")l(Q& -C) gives a straight line with a slope of 6.0~1.4 in agreement with simplified theoretical predictions. Half-lives of Rb and Cs nuclides measured by neutron decay curves are given. P", T&~2, on-line mass separation, polyethylene-moderated neutron counter.

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The activities Mo and Tc produced from neutron capture by natural Mo were chemically separated and studied using Ge(Li) p-ray detectors. Out of 185 transitions observed in the decay of Mo, 170 were assigned to 44 excited levels in Tc. For the decay of Tc, 26 of 27 transitions were placed among 10 excited levels in Hu. The interpretation of thẽ Tc level scheme using the shell. -model approach is not satisfactory even for a five-particle calculation. Systematics of odd-A level. structures in the region of A =101 indicate that the level structure of~O~T c could be due partly to the onset of col.lective effects.RADIOACTIVITY~Mo,~~Tc [from natural Mo(n, y)]; measured Ey, I y coin; deduced levels, logft's, 4,

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