Helium Clustering in Neutron-Rich Be Isotopes

Measurements of the helium-cluster breakup and neutron removal cross sections for neutron-rich Be isotopes A=10-12,14 are presented. These have been studied in the 30 to 42 MeV/u energy range where reaction measurements are proposed to be sensitive to the cluster content of the ground-state wave-function. These measurements provide a comprehensive survey of the decay processes of the Be isotopes by which the valence neutrons are removed revealing the underlying alpha-alpha core-cluster structure. The measurements indicate that clustering in the Be isotopes remains important up to the drip-line nucleus 14^Be and that the dominant helium-cluster structure in the neutron-rich Be isotopes corresponds to alpha-Xn-alpha.Comment: 5 pages, 2 tables and 3 figure

Breakup reaction studies of 10Be and 10,11B using a 10Be beam

The structure of 10Be has been investigated by inelastic scattering to states above the breakup threshold using the reaction 12C(10Be,10Be* → 6He+4/He)12C at Ebeam=302 MeV. Excited states in 10Be were observed at 9.6±0.1 and 10.2±0.1 MeV. No evidence was observed for the population of the 4 + member of the ground-state band of 10Be indicating the shell-model-like structure of the ground state. In addition, the decay of 8Be, 10B, and 11B, populated in the two-neutron, proton pickup, breakup and 1p pickup reactions, was reconstructed through the detection of coincident 4He+4He, 4He+6Li, and 4He+7Li particles. Cross sections for the formation of the 8Be, 9Be, 10B, and 11B were also deduced. Contrary to expectations, the two-neutron removal results in the production of 8Be predominantly (80%) in the first excited (2+) state. This suggests that dynamical excitations play an important role in the neutron removal process.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Breakup reaction studies of Be-10 and B-10,11 using a Be-10 beam

The structure of [Formula Presented] has been investigated by inelastic scattering to states above the breakup threshold using the reaction [Formula Presented] at [Formula Presented]. Excited states in [Formula Presented] were observed at [Formula Presented] and [Formula Presented]. No evidence was observed for the population of the [Formula Presented] member of the ground-state band of [Formula Presented] indicating the shell-model-like structure of the ground state. In addition, the decay of [Formula Presented], [Formula Presented], and [Formula Presented], populated in the two-neutron, proton pickup, breakup and [Formula Presented] pickup reactions, was reconstructed through the detection of coincident [Formula Presented], [Formula Presented], and [Formula Presented] particles. Cross sections for the formation of the [Formula Presented], [Formula Presented], [Formula Presented], and [Formula Presented] were also deduced. Contrary to expectations, the two-neutron removal results in the production of [Formula Presented] predominantly [Formula Presented] in the first excited [Formula Presented] state. This suggests that dynamical excitations play an important role in the neutron removal process. © 2004 The American Physical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Breakup reaction studies of 10Be and 10,11B using a 10Be beam

The structure of 10Be has been investigated by inelastic scattering to states above the breakup threshold using the reaction 12C(10Be,10Be* → 6He+4/He)12C at Ebeam=302 MeV. Excited states in 10Be were observed at 9.6±0.1 and 10.2±0.1 MeV. No evidence was observed for the population of the 4 + member of the ground-state band of 10Be indicating the shell-model-like structure of the ground state. In addition, the decay of 8Be, 10B, and 11B, populated in the two-neutron, proton pickup, breakup and 1p pickup reactions, was reconstructed through the detection of coincident 4He+4He, 4He+6Li, and 4He+7Li particles. Cross sections for the formation of the 8Be, 9Be, 10B, and 11B were also deduced. Contrary to expectations, the two-neutron removal results in the production of 8Be predominantly (80%) in the first excited (2+) state. This suggests that dynamical excitations play an important role in the neutron removal process.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Neutron removal and cluster breakup of 14B and 14Be

Measurements of the neutron removal and cluster breakup cross sections for the neutron-rich nuclei 14Be and 14B have been performed at 34.4 and 40.8 MeV/nucleon, respectively. Enhancement of the first chance cluster breakup cross section for 14Be compared to that of 14B provides evidence for a well-developed He cluster structure of the ground state of 14Be. Measurements of both the cross sections and decay-particle velocities suggest that multistep processes play an important role in the excitation and decay of both 14B and 14Be.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Measurements of the breakup and neutron removal cross sections for **16C

CHARISS

High-energy two-neutron removal from Be10

A kinetically complete measurement of the C12(Be10, α+α+n) and (Be10, α+α) 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 Be10, allowed the reconstruction of the excitation energy in the Be8 and Be9 systems. States in Be8 were identified, in particular the ground and first-excited states; and in Be9, 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 Be10 ground state and the two-step removal via inelastic excitations of the Be10(2+) and Be9(5/2-) excited states. © 2005 The American Physical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe