The spectra of $\gamma$ rays from the capture of neutrons by ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$ were measured at the Livermore 100-MeV linac for neutrons from 2 eV to 3 keV with a Ge(Li)-NaI three-crystal spectrometer. Neutron resonances were resolved to 200-eV neutron energy. Individual primary $\gamma$-ray transitions to final states in ${}_{}{}^{182}{}_{}{}^{}\mathrm{Ta}$ were resolved to 1778-keV excitation energy. These transitions were used to place 110 states with spin and parity assignments in the ${}_{}{}^{182}{}_{}{}^{}\mathrm{Ta}$ level diagram. A set of 1240 $E1$ transition strengths was extracted from 19 neutron resonances of known spin and parity. The most likely ${\chi }^2$ fit to the distribution of these widths yielded 1.38 ± 0.11 degrees of freedom. The $E1$ transition strengths were also examined for correlations with the reduced neutron widths of the initial and final states. The $E1$ strength function was extracted for $E_{\gamma }=4.3\mathrm{} \mathrm{to} 6.1$ MeV and compared with previous results.

NUCLEAR REACTIONS ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}(n,\gamma )$, $E=2\mathrm{} \mathrm{eV}-3 \mathrm{keV}$ measured $\sigma (E,E_{\gamma })$, $E_{\gamma }$, $I_{\gamma }$; deduced $Q$, ${}_{}{}^{182}{}_{}{}^{}\mathrm{Ta}$ levels; extracted ${\Gamma }_{\gamma i}$ distribution, strength function, correlation coefficients. Natural target, three-crystal Ge(Li)-NaI spectrometer.

• Received 27 December 1976

DOI:https://doi.org/10.1103/PhysRevC.16.574