Study of 83-Neutron Nuclei by Deuteron Stripping Reactions

Abstract

A study of the 83-neutron nuclei ${\mathrm{Ba}}^{138}$, ${\mathrm{La}}^{139}$, and ${\mathrm{Pr}}^{141}$ was made by the ($d, p$) stripping reaction with 11-MeV deuterons. The outgoing protons were analyzed with a magnetic spectrometer, and angular distributions were measured for the well-resolved states. Excited levels, with spins and parities indicated in parentheses, were found at 0 ($\frac{7}{2}$-), 0.59 ($\frac{3}{2}$-), 1.07, 1.39, 1.67 ($\frac{5}{2}$-), 1.20 (½-), 2.44 (½-) MeV in ${\mathrm{Ba}}^{139}$; at 0 ($g_{\frac{7}{2}}{f}_{\frac{7}{2}}$), 0.25 ($g_{\frac{7}{2}}{f}_{\frac{7}{2}}$), 0.60 ($g_{\frac{7}{2}}{p}_{\frac{3}{2}}$), 0.71 ($g_{\frac{7}{2}}{p}_{\frac{3}{2}}$), 1.02, 1.31, 1.37, 1.46, 1.80, 1.88, 1.95, and 2.13 MeV in ${\mathrm{La}}^{140}$ ($d_{\frac{5}{2}}{f}_{\frac{7}{2}}$), 0.62 ($d_{\frac{5}{2}}{p}_{\frac{3}{2}}$), 1.02 ($d_{\frac{5}{2}}{p}_{\frac{3}{2}}$), 1.38 ($d_{\frac{5}{2}}{p}_{\frac{3}{2}}$), and 2.12 MeV in ${\mathrm{Pr}}^{142}$. The angular distributions were fitted with a distorted-wave Born approximation calculation to determine the angular momentum transfer. The absolute $Q$ values obtained agree with previous measurements. A comparison is made with earlier measurements on the 83-neutron nucleus ${\mathrm{Ce}}^{141}$.