Search for the proposed near-threshold proton-emission resoance in ¹¹B and its implication on βp decay from ¹¹Be

Unusually large decay branching ratio for beta-delayed proton emission from the halo nucleus 11Be was first observed indirectly through detection of the final state nucleus 10Be using the accelerator mass spectroscopy technique. Direct observation of proton emission was claimed by a radioactive beam measurement at TRIUMF with the AT-TPC device, showing evidence of a possible new near-threshold resonance at excitation energy of 11.425 MeV in 11B. Other evidence of such a resonance was also shown in two other different radioactive experiments. However, a recent experiment via 10Be(d,n) uing the neutron time-of-flight technique find no evidence of its existence. At Notre Dame, we conducted a relative simple stable beam experiment to search for this propopsed resonance, by scaning the excitation energy range in 11B through two channels of 7Li(a,a) and 7Li(a,p) to populate near-threshold levels in 11B. The time-of-flight technique was used to separate different particle species and angular distributions from 20 to 150 degrees in the lab frame were measured. Preliminary results will be reported and its implication on possible new physics will also be discussed.