High-energy two-neutron removal from ¹⁰Be

A kinetically complete measurement of the C-12(Be-10, alpha+alpha+n) and (Be-10, alpha+alpha) reactions has been performed at a beam energy of 30 MeV/nucleon. The charged beam velocity particles were detected in an array of Si-CsI detectors placed at zero degrees, and the neutrons in an 81-element neutron array. The coincident detection of the final-state particles, produced in the breakup of Be-10, allowed the reconstruction of the excitation energy in the Be-8 and Be-9 systems. States in Be-8 were identified, in particular the ground and first-excited states; and in Be-9, states at 1.68, 2.43, and (2.78, 3.05) MeV were observed. The population of these levels, in particular the 2.43 MeV 5/2(-) level, suggests that collective excitations play an important role in the neutron removal process. Distorted wave Born approximation and Glauber-type calculations have been used to model the direct neutron removal from the Be-10 ground state and the two-step removal via inelastic excitations of the Be-10(2(+)) and Be-9(5/2(-)) excited states.