Gamma-rays from the Reaction Al27 (p, γ)Si28

Abstract

Gamma-rays from the reaction Al 27 ( p , γ)Si 28 have been studied at the four resonances occurring at E p =226, 294, 326, and 405 kev by the use of a large NaI crystal scintillation spectrometer. The gamma-ray transitions from the resonance states to the levels in Si 28 at 1.78 Mev(1st), 4.62 Mev(2nd), 6.91 Mev, and 8.58 Mev were observed. Spins and parities of these levels and some of the resonance levels are deduced from the anisotropies of gamma-rays as follows: 4.62 Mev, J =4 (+) ; 6.91 Mev, J =2 ± or 4 + ; 8.58 Mev, J =3 + ; 11.90 Mev, J =4 (-) ; 11.98 Mev, J =4 - . J =4 (+) for the second excited state suggests the collective nature of this excited v level which has been expected from the other evidences found in neighbouring nuclei. The gamma-ray yield and the branching ratios of each resonance level are also given.