A resonance problem on the low-lying resonant state in the 9Be system

Abstract

The photo-disintegration cross section of 9Be is investigated in a framework of the α + α + n three-body cluster model. Much interest is concentrated on the nature of the 1/2+ state of 9Be located just above the three-body threshold. The existence of this 1/2+ resonance is a long-standing problem and has been a topic of quite interest in relation to the breakup mechanism of 9Be into the 8Be(0+)+n and (α + α + n) channels. The newly measured breakup cross sections of the 1/2+ state of Ref. [1] is inconsistent with the old experimental values [2, 3]. The purpose of this study is to clarify the properties of the 1/2+ state of 9Be with the possibility of a genuine three-body (α + α + n) resonance or the two-body (8Be(0+)+n) virtual state.