EVIDENCE FOR HALO IN QUENCHING OF HE-6 BETA-DECAY INTO ALPHA AND DEUTERON

The He-6 beta decay into a and deuteron is studied with different simple models and with a semi-microscopic model based on variational microscopic wave functions expanded in a three-center harmonic-oscillator basis. The latter approach allows us to show that this decay is quenched by a cancellation between the internal and halo contributions to the Gamow-Teller matrix element. An extreme sensitivity to the halo description up to distances as large as 15 fm is observed. Contrary to several available effective forces, the Volkov force V2 reproduces the measured beta-decay transition probabilities.