Neutron-Capture Gamma-Ray Studies of the Level Structure of theTe124Nucleus

The $\gamma$-ray spectrum resulting from thermal-neutron capture in ${\mathrm{Te}}^{123}$ was investigated with the Argonne 7.7-m bent-crystal spectrometer. The observed spectrum consisted of 75 $\gamma$ rays with energies between 100 keV and 1.1 MeV. The spectrometer used a new split-source technique which allowed simultaneous measurement of the ${\mathrm{Te}}^{123}(n, \gamma ){\mathrm{Te}}^{124}$ spectrum from capturing samples with two different isotopic enrichments of ${\mathrm{Te}}^{123}$ and thus gave immediate isotopic identification for the ($n, \gamma$) spectrum. The ${\mathrm{Te}}^{123}(n, \gamma ){\mathrm{Te}}^{124}$ spectrum was also measured with Ge(Li) detectors in the energy regions 0.5-4.0 MeV (112 lines) and 5.5-9.5 MeV (63 lines) by use of the Argonne in-pile facility. The associated spectrometer has a long, split NaI ring which surrounds a Ge(Li) detector and was used to enhance the full-energy spectrum (anticoincidence) and the double-escape spectrum (coincidence). The above thermal-neutron-capture spectrum was combined with the results of an average-resonance-capture spectrum taken with the same Ge(Li) facility but with the target surrounded with boron. These ($n, \gamma$) experiments were then combined with all previous work to develop and extend the level scheme of ${\mathrm{Te}}^{124}$ and to define many of the details of the $\gamma$ decay of these levels. The new values for the first 15 level energies (keV) and $J^{\pi }$ are ground state, $0^{+}$; 602.42±0.02, $2^{+}$; 1247.99±0.05, $4^{+}$; 1324.82±0.05, $2^{+}$; (1655.9±0.2, $0^{+}$); (1736.5±0.3); (1747.40±0.16); 1956.18±0.11, $3^{\pm }$, $4^{+}$; 2037.68±0.07, $2^{+}$; 2090.65±0.35, $0^{+}$, $2^{+}$; 2152.04±0.15, $0^{+}$, $2^{+}$; 2181.20±0.40, 1, 2; 2293.10±0.30, $3^{-}$; 2322.57±0.20, $0^{+}$, $2^{+}$; 2452.9±2.6, $0^{+}$, $2^{+}$. The parentheses indicate uncertainty in the level assignments, while the italic numerals indicate new spin and parity values. The relative...