The γ-ray spectrum resulting from thermal-neutron capture in Te123 was investigated with the Argonne 7.7-m bent-crystal spectrometer. The observed spectrum consisted of 75 γ rays with energies between 100 keV and 1.1 MeV. The spectrometer used a new split-source technique which allowed simultaneous measurement of the Te123(n,γ)Te124 spectrum from capturing samples with two different isotopic enrichments of Te123 and thus gave immediate isotopic identification for the (n,γ) spectrum. The Te123(n,γ)Te124 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,γ) experiments were then combined with all previous work to develop and extend the level scheme of Te124 and to define many of the details of the γ decay of these levels. The new values for the first 15 level energies (keV) and Jπ 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±, 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 intensities of γ rays from states at ∼2 MeV suggest that E2 transitions to the two-phonon states at 1248 and 1325 keV are enhanced relative to transitions to states at 0 and 602 keV; so these 2-MeV levels are very likely collective and possibly vibrational. The (n,γ) data imply a neutron binding energy En=9425±2keV for Te124. © 1969 The American Physical Society.
