Structure of 12Be: intruder d-wave strength at N=8

The breaking of the N=8 shell-model magic number in the 12Be ground state has been determined to include significant occupancy of the intruder d-wave orbital. This is in marked contrast with all other N=8 isotones, both more and less exotic than 12Be. The occupancies of the 0 hbar omega neutron p1/2-orbital and the 1 hbar omega, neutron d5/2 intruder orbital were deduced from a measurement of neutron removal from a high-energy 12Be beam leading to bound and unbound states in 11Be.Comment: 5 pages, 2 figure

Spectroscopic studies of Dy-168,170 using CLARA and PRISMA

Preliminary results from an experiment aiming at Dy-170. Submitted to the LNL Annual Report 2008.Comment: 2 pages, 4 figures, Submitted to the LNL Annual Report 200

The detection of neutron clusters

A new approach to the production and detection of bound neutron clusters is presented. The technique is based on the breakup of beams of very neutron-rich nuclei and the subsequent detection of the recoiling proton in a liquid scintillator. The method has been tested in the breakup of 11Li, 14Be and 15B beams by a C target. Some 6 events were observed that exhibit the characteristics of a multineutron cluster liberated in the breakup of 14Be, most probably in the channel 10Be+4n. The various backgrounds that may mimic such a signal are discussed in detail.Comment: 11 pages, 12 figures, LPCC 01-1

Three-body correlations in Borromean halo nuclei

Three-body correlations in the dissociation of two-neutron halo nuclei are explored using a technique based on intensity interferometry and Dalitz plots. This provides for the combined treatment of both the n-n and core-n interactions in the exit channel. As an example, the breakup of 14Be into 12Be+n+n by Pb and C targets has been analysed and the halo n-n separation extracted. A finite delay between the emission of the neutrons in the reaction on the C target was observed and is attributed to 13Be resonances populated in sequential breakup.Comment: 5 pages, 4 figures, submitted to PR

Coulomb excitation of exotic nuclei at the R3B-LAND setup

Exotic Ni isotopes have been measured at the R3B-LAND setup at GSI in Darmstadt, using Coulomb excitation in inverse kinematics at beam energies around 500 MeV/u. As the experimental setup allows kinematically complete measurements, the excitation energy was reconstructed using the invariant mass method. The GDR and additional low-lying strength have been observed in 68Ni, the latter exhausting 4.1(1.9)% of the E1 energy-weighted sum rule. Also, the branching ratio for the non-statistical decay of the excited 68Ni nuclei was measured and amounts to 24(4)%.Comment: 11 pages, 7 figures. Invited Talk given at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

1n- and 2n-transfer with the Borromean nucleus 6^{6}He near the Coulomb barrier

Accepetd for publication in Physical Review LettersAngular distributions for 1n- and 2n-transfer are reported for the 6He + 65Cu system at Elab = 22.6 MeV. For the first time, triple coincidences between particles, neutrons and characteristic rays from the target-like residues were used to separate the contributions arising from 1n- and 2n-transfer. The differential cross sections for these channels, elastic scattering, and fusion were analyzed using a Coupled Reaction Channels approach. The large measured ratio of the 2n/1n cross section and the strong influence of 2n-transfer on other channels indicate that the di-neutron configuration of 6He plays a dominant role in the reaction mechanism

Quasiparticle alignments and alpha-decay fine structure of Pt-175

Excited states and decay properties of 175 Pt have been investigated using the 92 Mo ( 86 Sr , 2 p n ) fusion-evaporation reaction. The JUROGAM I γ -ray spectrometer and the GREAT spectrometer were used in conjunction with the gas-filled recoil separator RITU for the measurement of the radiation at the target and focal plane positions, respectively. Two new band structures, assigned to be based on the I π = ( 7 / 2 − ) ground state in 175 Pt, have been established and the known yrast band has been extended up to I π = ( 49 / 2 + ) . Rotational properties of the excited states in 175 Pt have been investigated within the cranked shell-model formalism. The low-frequency changes in the alignments of the positive- and negative-parity bands are interpreted as a sign of proton-pair excitations in the rotating core. Furthermore, the α -decay measurements reveal a candidate for a fourth α -decay branch in 175 Pt, feeding a non-yrast state in 171 Os

Structure around the island of inversion with single-neutron knockout reactions at GANIL

The nuclear structure of the 31Mg nucleus has been studied with the singleneutron knockout reaction. We report on the preliminary results of an experiment performed with the EXOGAM array coupled, for the first time, to the SPEG spectrometer at GANIL.We present a provisional result for the inclusive single-neutron knockout cross section of σinc= 90(5) mb. Preliminary exclusive cross sections for the measured bound states, including the ground state, are also presented. Finally, preliminary longitudinal momentum distributions for the ground state and first excited state are also shown. These results are compared to Monte Carlo Shell-Model calculations in the sd-pf region