Angular correlation studies of electromagnetic transitions following the 16O(τ, α)15O reaction

Abstract

Abstract A particle-gamma angular correlation coincidence technique enabling the measurement of 0° coincidences was used to study levels in 15 O at 5.24 MeV (J π = 5 2 + ) , 6.18 MeV (J π = 3 2 − ) , 6.79 MeV (J π = 3 2 + ) and 6.86 MeV (J π = 5 2 + ) . The multipole mixing ratios of the de-excitation γ-rays were determined as the following: x (5.24→ 0) = +0.08±0.08 an E3/M2 mixture; x (6.86 → 5.24) = +0.04±0.03, an E2/M1 mixture; x (6.79 → 0) = −0.02±0.02, an M2/E1 mixture and x (6.18 → 0) = −0.121 ±0.008 an E2/M1 mixture. The latter value is to be compared with x (( E 2/ M 1) = +0.13 ±0.02 for the mirror 6.323 MeV transition in 15 N indicating |x( 15 O )| ≦ |x( 15 N )| contrary to previous findings (10). The results obtained, together with those corresponding to mirror transitions in 15 N are compared with recent IPM and core polarization theoretical investigations.