Study of the Levels inLa140by (d,p) Stripping Reaction

The energy levels in ${}_{}{}^{140}{}_{}{}^{}\mathrm{La}$ were studied by means of ($d,p$) reaction spectroscopy using 10-MeV deuterons. The protons that emerged were analyzed by a single-gap, broad-range magnetic spectrograph with 13-keV resolution. We obtained the reaction $Q$ value of 2938±3 keV. Exposures were taken at eight angles ranging from 25° to 105°. All spectra were fitted, using a least-squares code, up to an excitation energy of 1860 keV. Seventy states were observed and the angular distributions of the most prominent groups were analyzed by means of distorted-wave Born-approximation stripping theory. Spins of the ${}_{}{}^{140}{}_{}{}^{}\mathrm{La}$ levels determined from previous decay-scheme studies and the present research, and the proton intensities observed in the ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}\mathrm{}(d,p)\mathrm{}$ ${}_{}{}^{140}{}_{}{}^{}\mathrm{La}$ reaction, can be satisfactorily explained in terms of the mixed configurations, ${\left(1\mathrm{}{g}_{\frac{7}{2}}\right)}_p{\left(2\mathrm{}{f}_{\frac{7}{2}}\right)}_n$ and ${\left(2\mathrm{}{d}_{\frac{5}{2}}\right)}_p{\left(2\mathrm{}{f}_{\frac{7}{2}}\right)}_n$. Above 600 keV, however, interpretation of states in terms of higher energy configurations appears also to require phonon-particle coupling.