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\ifmmode\pm\else\textpm\fi{}4, 475\ifmmode\pm\else\textpm\fi{}5, 630\ifmmode\pm\else\textpm\fi{}6, 695\ifmmode\pm\else\textpm\fi{}7, 745\ifmmode\pm\else\textpm\fi{}8, 765\ifmmode\pm\else\textpm\fi{}8, 1050\ifmmode\pm\else\textpm\fi{}10, 1105\ifmmode\pm\else\textpm\fi{}8, 1110\ifmmode\pm\else\textpm\fi{}11, 1365\ifmmode\pm\else\textpm\fi{}10, 1565\ifmmode\pm\else\textpm\fi{}13, 1795\ifmmode\pm\else\textpm\fi{}15, 2040\ifmmode\pm\else\textpm\fi{}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 $\frac{E2}{M1}>~225$ for the 630-kev transition (2+ \ensuremath{\rightarrow} 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\ifmmode\pm\else\textpm\fi{}0.3. The intensity of the annihilation gamma rays decays with a half-life of 205\ifmmode\pm\else\textpm\fi{}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 ${\mathrm{Rh}}^{102}$.