Observation of β-delayed 2He emission from the proton-rich nucleus 22Al

The β-delayed two-proton emission from 22Al was investigated experimentally through the implantation-decay method. A β-delayed two-proton decay branch from 22Al were identified based on the coincidence of the charged particles and γ-ray signals. The relative momentum (qpp) and the opening angle (θpp) distributions of the two β-delayed protons are measured and a strong peak at qpp∼20MeV/c, as well as a peak at θpp∼30∘ are observed clearly. The β-delayed 2He emission from 22Al with a probability of 29 (13)% by fitting the experimental data with the results of Monte Carlo simulations.