Search for beta-delayed proton emission from 11Be

We report on an attempt to reproduce the observation of beta(-)-delayed proton emission from Be-11 through detection of the final state nucleus Be-10 with accelerator mass spectrometry. Twelve samples were collected at the ISOLDE facility at CERN at different separator settings, allowing tests of different sources of contamination to be carried out. The observed amounts of Be-10 per collected Be-11 rule out several contamination sources, but do not agree internally. Formation of BeH molecular ions in the ion source may explain our data, in which case an upper limit of the beta p branching ratio of 2.2 x 10(-6) can be derived.