Beta decay asymmetry in mirror nuclei: A=9

Investigations of light nuclei close to the drip lines have revealed new and intriguing features of the nuclear structure. The occurrence of halo structures in loosely bound systems has had a great impact on the nuclear physicsresearch in the last years, as intriguing, but not yet solved, is the nature of transitions with very large beta strength. We report here on the investigation of this latter feature by an accurate measurement of the beta decayasymmetry between the mirror nucleiin the A=9 mass chain.