Investigation of particle-unbound excited states in light nuclei with resonance-decay spectroscopy using a Be12 beam

Resonance-decay spectroscopy is used to study particle-unbound excited states produced in interactions of E/A=50 MeV Be12 on polyethylene and carbon targets. The particle-unbound states are produced in a variety of reaction mechanisms, ranging from projectile fragmentation to proton pickup. New proton-decaying excited states are observed in Li9(E*=14.1±0.1 MeV, Γ=207±49 keV) and Be10(E*=20.4±0.1 MeV, Γ=182±74 keV). In addition a new α-decaying state is observed in B13(E*=13.6±0.1 MeV, Γ≤320 keV). Also found was a Be8 state with E*=23 MeV, Γ=616±30 keV, which decays to the p+3H+α channel. Correlation between the fragments indicates that the decay is initiated by a proton emission to the 4.63-MeV state of Li7 and the spin of the state is J>2. A second T=2 state was confirmed in B12 at 14.82 MeV, which decays to the p+11Be, 3H+9Be, and α+8Li channels. Its width was found to be Γ≤100 keV and its spin is consistent with Jπ=2+. © 2008 The American Physical Society.link_to_subscribed_fulltex