Direct Observation of Competing M1 and M3 Transitions in B 10

AbstraktAbstract

Excited states in 10B were populated with the 10Bðp; p0γÞ10B reaction at 8.5 MeV and their γ decay was investigated via coincidence γ-ray spectroscopy. The emitted γ rays were measured using large-volume LaBr3∶Ce and CeBr3 detectors placed in anti-Compton shields. This allowed the observation of weak γ-ray transitions, such as the M3 transition between the Jπ ; T ¼ 0þ; 1 isobaric analog state (IAS) and the Jπ ; T ¼ 3þ; 0 ground state and the E2 transition between the Jπ ; T ¼ 2þ 1 ; 0 state and the IAS, i.e., performing measurements of branching ratios at the level of λ ≥ 10−4. For the first time in 10B, the competing M1 and M3 transitions from the decay of the IAS have been observed in a γ spectroscopy experiment. The experimental results are compared with ab initio no-core shell model calculation using the newest version of the local position-space chiral N3LO nucleon-nucleon interaction. The calculations reproduce correctly the ordering of the bound states in 10B, and are in reasonable agreement with the observed branching ratios and reduced transition probabilities.

Excited states in 10B were populated with the 10Bðp; p0γÞ10B reaction at 8.5 MeV and their γ decay was investigated via coincidence γ-ray spectroscopy. The emitted γ rays were measured using large-volume LaBr3∶Ce and CeBr3 detectors placed in anti-Compton shields. This allowed the observation of weak γ-ray transitions, such as the M3 transition between the Jπ ; T ¼ 0þ; 1 isobaric analog state (IAS) and the Jπ ; T ¼ 3þ; 0 ground state and the E2 transition between the Jπ ; T ¼ 2þ 1 ; 0 state and the IAS, i.e., performing measurements of branching ratios at the level of λ ≥ 10−4. For the first time in 10B, the competing M1 and M3 transitions from the decay of the IAS have been observed in a γ spectroscopy experiment. The experimental results are compared with ab initio no-core shell model calculation using the newest version of the local position-space chiral N3LO nucleon-nucleon interaction. The calculations reproduce correctly the ordering of the bound states in 10B, and are in reasonable agreement with the observed branching ratios and reduced transition probabilities.