Decay ofRh102→Ru102

Abstract

The singles and coincident spectra of the gamma rays from the decay of ${\mathrm{Rh}}^{102}$, which was produced by the ($p, n$) reaction on ruthenium containing 97.2% ${\mathrm{Ru}}^{102}$, have been measured with scintillation spectrometers. The energies (in kev) of the gamma rays are: 415±4, 475±5, 630±6, 695±7, 745±8, 765±8, 1050±10, 1105±8, 1110±11, 1365±10, 1565±13, 1795±15, 2040±14, and 511 (annihilation gamma rays). Spins of the levels in ${\mathrm{Ru}}^{102}$ which are consistent with the directional angular correlations of gamma-ray cascades are: 475(2+), 1105(2+ and 4+, doublet), 1525(3), 1840(0+), 1870(3, 4, 5, or 6), 2040(2+), 2220(3), and 2270(?). A value of $\frac{E2\mathrm{}}{M1\mathrm{}}>~225$ for the 630-kev transition (2+ → 2+) was deduced from the composite correlation of the 630-475 kev cascades. The branching ratio of cascade to crossover transitions from the decay of the second 2+ state is 1.5±0.3. The intensity of the annihilation gamma rays decays with a half-life of 205±10 days. Gamma-ray spectra have been measured as a function of time for 920 days and a change in the relative population of the states is observed. From this we infer the existence of a long-lived isomeric state in ${\mathrm{Rh}}^{102}$.