High-energy two-neutron removal from $^{10}$Be

Expérience GANILA kinetically complete measurement of the $^{12}$C($^{10}$Be, alpha+alpha+n) and ($^{10}$Be, 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 $^{10}$Be, allowed the reconstruction of the excitation energy in the $^{8}$Be and $^{9}$Be systems. States in $^{8}$Be were identified, in particular the ground and first-excited states; and in $^{9}$Be, 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 10Be ground state and the two-step removal via inelastic excitations of the $^{10}$Be(2$^{+}$) and $^{9}$Be(5/2$^{-}$) excited states