LOW-LYING STATES IN RB86 FROM (D,P), (D,T), AND (N,GAMMA) REACTIONS

The energy levels of Rb86 have been studied through the neutron stripping and pickup reactions Rb85(d, p)Rb86 and Rb87(d, t)Rb86, and the thermal-neutron-capture reaction Rb85(n, γ)Rb86. Enriched targets were bombarded with 12-MeV deuterons, and proton and triton spectra were observed with a magnetic spectrograph; proton angular distributions were compared with a distorted-wave Born-approximation (DWBA) calculation. Thermal-neutron-capture γ-ray spectra from both enriched Rb85 and natural rubidium targets have been studied in the energy intervals 50-2000 keV and 5000-8500 keV with a Ge(Li) spectrometer system. 32 low-energy γ-ray transitions were incorporated into a level scheme defined by the combined (d, p), (d, t), and the primary (n, γ) measurements. Tentative spin and parity assignments for 18 levels below 1505 keV are proposed on the basis of assigned orbital angular momentum transfers and γ-ray population and decay modes. The low-lying states of Rb86 are discussed in terms of shell-model proton-neutron configurations; comparison is made with a zero-range spin-dependent calculation. Although correlation between the data and positive parity levels predicted by the simple model is not entirely satisfactory, reasonable agreement has been found for low-lying negative parity levels. © 1969 The American Physical Society.