Study of the energy levels of ⁶⁹Ga using nuclear photoexcitation

Elastic and inelastic scattering of monochromatic photons were used for studying nuclear energy levels in ⁶⁹Ga; the photons were produced by thermal neutron capture in copper and vanadium. The decay of one resonance at 7306 keV excited by the copper γ source and another resonance at 6874 keV excited by the vanadium γ source were studied in detail and 30 low-lying levels were observed from the ground state up to 3.4 MeV, 17 of which are believed to be new levels in ⁶⁹Ga. The angular distribution of some elastic and inelastic lines were measured and the following spin determinations were made (keV, J^π): 320, 1/2^-, (3/2^-); 574, 5/2^-; 872, 3/2^-; 1488, 3/2^-, 7/2^-; 1525 (1/2, 3/2); 1891, 3/2^- (1978), (1/2, 3/2); 2457, 3/2; 2484, 5/2; (2565), (1/2, 3/2); 2660, 3/2; 3051, (3/2, 7/2); 3076, 5/2; 3318, (7/2); 6874, 1/2⁽⁺⁾ and 7306, 5/2⁺, where parentheses denote uncertain Jπ assignments. The parity of the 7306-keV level was directly determined using a Compton polarimeter. The total radiative width of the 7306-keV level was measured and found to be Γ=0.105±0.020 eV. For the 6874-keV level, a positive correlation coefficient was obtained, ρ=0.69, between the (γ,γ′) and (d,n) transition strengths leading to the same final states in ⁶⁹Ga. The levels of ⁶⁹Ga are compared with recent theoretical calculations.