Excited states of 12C above the alpha-decay threshold

Abstract

The excitation energy spectrum of 12C is important for both structural and astrophysical reasons; here we present evidence for a new state in 12C. The two reactions 12C(4He, 4He+4He+4He)4He and 9Be(4He,4He+4He+4He)n were measured using an array of four double sided strip detectors. Excited states in 12C were reconstructed filtered by the condition that the alpha-decay proceeded via the 8Be ground-state. In both measurements evidence was found for a new state at 13.3(0.2) MeV with a width 1.7(0.2) MeV. Angular correlation measurements from the 12C(4He, 4He+4He+4He)4He reaction indicates that the state may have J π=4+. © Published under licence by IOP Publishing Ltd.