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The neutron-rich isotopes Fe65,67 and Co65 have been produced at the LISOL facility, Louvain-La-Neuve, in the proton-induced fission of U238. Beams of these isotopes have been extracted with high selectivity by means of resonant laser ionization combined with mass separation. Yrast and near-yrast levels of Co65 have also been populated in the Ni64+U238 reaction at Argonne National Laboratory. The level structure of Co65 could be investigated by combining all the information from both the Fe65 and Co65β decay and the deep-inelastic reaction. The Fe65, Co65, and Fe67 decay schemes and the Co65 yrast structure are fully established. The Co65,67 level structures can be interpreted as resulting from the coexistence of core-coupled states with levels based on a low-energy proton-intruder configuration. © 2009 The American Physical Society.

Excited states in the odd-AGa71,73,75,77 nuclei have been populated in deep-inelastic reactions of a Ge76 beam at 530 MeV with a thick U238 target. High-spin sequences built upon the 9/2+, 5/2-, and 3/2- states were identified in all four isotopes. A comparison of the observed structures with the yrast positive-parity states in the neighboring even-even Zn cores indicates that the newly identified levels may be regarded as arising from the relatively weak coupling of the odd proton to the core states. However, significant contributions from broken pairs are expected to be present in this region of excitation energy. The present data set also provides clarification of previously reported decay paths of the low-energy levels in Ga71,73,75,77. © 2009 The American Physical Society.

The high-spin yrast structure of the 210Bi nucleus was investigated using -ray coincidence spectroscopy following deep-inelastic reactions in the 208Pb+208Pb system. Cascades of rays following the decay of a new isomer were identified. Spin-parity assignments to the states known from previous studies as well as to newly located excitations were made based on the measured angular distributions of rays combined with a transition conversion coefficient analysis.

Excited states in the N = 30 neutron-rich 49K have been studied using multi-nucleon transfer reactions with thin targets and the PRISMA-CLARA spectrometer combined with thick-target - coincidence data from Gammasphere. The d3/2 proton-hole state is located 92 keV above the s1/2 ground state and the proton-particle f7/2 state is suggested at 2104 keV. Three other levels are established as involving the coupling to 2+ of two neutrons above the N = 28 shell. The measured or estimated lifetimes served to reinforce the interpretation of the observed level structure which is found to be in satisfactory agreement with shell model calculations.

Lifetimes of low-lying excited states of the neutron-rich 44, 46Ar nuclei, populated via multinucleon transfer reactions, are measured by means of the differential recoil distance Doppler shift method. The extracted electromagnetic transition probabilities are compared with previous intermediate-energy Coulomb-excitation measurements and with large-scale shell-model calculations. The increase in the deduced B(E2 ; 2+→0+) transition probability from 44Ar to the closed-shell nucleus 46Ar contradicts the earlier results of Coulomb-excitation experiments. Shell-model calculations using different effective interactions agree with the new measured values.

The neutron-rich isotopes Fe65,67 and Co65 have been produced at the LISOL facility, Louvain-La-Neuve, in the proton-induced fission of U238. Beams of these isotopes have been extracted with high selectivity by means of resonant laser ionization combined with mass separation. Yrast and near-yrast levels of Co65 have also been populated in the Ni64+U238 reaction at Argonne National Laboratory. The level structure of Co65 could be investigated by combining all the information from both the Fe65 and Co65β decay and the deep-inelastic reaction. The Fe65, Co65, and Fe67 decay schemes and the Co65 yrast structure are fully established. The Co65,67 level structures can be interpreted as resulting from the coexistence of core-coupled states with levels based on a low-energy proton-intruder configuration. © 2009 The American Physical Society.

The neutron-rich isotopes 65,67Fe and 65Co have been produced at the LISOL facility, Louvain-La-Neuve, in the proton-induced fission of 238U. Beams of these isotopes have been extracted with high selectivity by means of resonant laser ionization combined with mass separation. Yrast and near-yrast levels of 65Co have also been populated in the 64Ni+238U reaction at Argonne National Laboratory. The level structure of 65Co could be investigated by combining all the information from both the 65Fe and 65Co beta decay and the deep-inelastic reaction. The 65Fe, 65Co and 67Fe decay schemes and the 65Co yrast structure are fully established. The 65,67Co level structures can be interpreted as resulting from the coexistence of core-coupled states with levels based on a low-energy proton-intruder configuration., 17 pages, 13 figures, preprint

New level structures are proposed for neutron-rich127,129,131In populated in the decay of127,129,131Cd. No evidence for the presence of 1-particle- 2-hole intruder structures in the neutron-rich In isotopes is observed.

The lifetimes of the first excited states of the N=30 isotones Ca-50 and Sc-51 have been determined using the Recoil Distance Doppler Shift method in combination with the CLARA-PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. This extends the lifetime knowledge beyond the f(7/2) shell closure and allows us to derive the effective proton and neutron charges in the fp shell near the doubly magic nucleus Ca-48, using large-scale, shell-model calculations. These results indicate an orbital dependence of the core polarization along the fp shell.

The neutron-rich isotopes Fe65,67 and Co65 have been produced at the LISOL facility, Louvain-La-Neuve, in the proton-induced fission of U238. Beams of these isotopes have been extracted with high selectivity by means of resonant laser ionization combined with mass separation. Yrast and near-yrast levels of Co65 have also been populated in the Ni64+U238 reaction at Argonne National Laboratory. The level structure of Co65 could be investigated by combining all the information from both the Fe65 and Co65β decay and the deep-inelastic reaction. The Fe65, Co65, and Fe67 decay schemes and the Co65 yrast structure are fully established. The Co65,67 level structures can be interpreted as resulting from the coexistence of core-coupled states with levels based on a low-energy proton-intruder configuration.

The lifetimes of the first excited states of the N=30 istones 50Ca and 51Sc have been determined using a novel techinique that combines the Recoil Distance Doppler Shift method with the CLARA-PRISMA sepctrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. This exteneds the lifetime knowledge beyond the f7/2 shell closure and allows to derive the effective proton and neutron charges in the fp shell near the doubly-magic nucleus 48Ca, using large-scale shell-model claculations. These results seem to indicate an orbital dependence of the core polarization along the fp shell.

Excited states in the odd-AGa71,73,75,77 nuclei have been populated in deep-inelastic reactions of a Ge76 beam at 530 MeV with a thick U238 target. High-spin sequences built upon the 9/2+, 5/2-, and 3/2- states were identified in all four isotopes. A comparison of the observed structures with the yrast positive-parity states in the neighboring even-even Zn cores indicates that the newly identified levels may be regarded as arising from the relatively weak coupling of the odd proton to the core states. However, significant contributions from broken pairs are expected to be present in this region of excitation energy. The present data set also provides clarification of previously reported decay paths of the low-energy levels in Ga71,73,75,77.

Two prompt γ rays of energies 2020 and 554 keV were observed in coincidence with delayed transitions depopulating the 19/2- isomer in the Z=29, N=42 Cu71 nucleus. The newly identified transitions are proposed to deexcite the 4776- and 5330-keV levels above the 19/2- isomer. Based on the comparison with the low-lying positive-parity states observed in the Z=42, N=50 Mo92 nucleus, spin and parity 23/2- are proposed for the 4776-keV level in Cu71. The high-energy, 2020-keV transition is interpreted as arising from the breaking of the N=40 neutron core. Shell-model calculations with a Ni56 core reproduce the (23/2-)→(19/2-) gap well, suggesting that the 23/2- state is dominated by πp3/2ν((fp)10(g9/2)4) configurations. The present result constitutes further evidence supporting the view that the N=40 subshell closure persists in Cu71, herewith challenging recent suggestions that the coupling of two or more proton or neutron quasiparticles induces a large polarization of the Ni68 core. © 2009 The American Physical Society.

The low-lying yrast states in the Ca-51 and Sc-52 nuclei were investigated to obtain information on the evolution of the p(1/2) and f(5/2) neutron single-particle orbitals in neutron-rich nuclei near proton number Z=20. Level structures associated with neutron excitations into these two orbitals and with proton excitations across the Z=20 shell gap were identified. Shell-model calculations with the recently proposed GXPF1A interaction account reasonably well for the fp-shell states. The energy separation between the nu p(1/2) and nu f(5/2) orbitals in the Ca isotopes appears to be overestimated by the GXPF1A Hamiltonian.

The lifetimes of the first excited states of nuclei around the doubly-magic nucleus 48Ca have been determined using a novel method that combines the Recoil Distance Doppler Shift (RDDS) method with the CLARA-PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. This novel method and some preliminary results on lifetimes are presented.

The low-lying yrast states in the 51 Ca and 52 Sc nuclei were investigated to obtain information on the evolution of the p 1 / 2 and f 5 / 2 neutron single-particle orbitals in neutron-rich nuclei near proton number Z = 20. Level structures associated with neutron excitations into these two orbitals and with proton excitations across the Z = 20 shell gap were identified. Shell-model calculations with the recently proposed GXPF1A interaction account reasonably well for the fp -shell states. The energy separation between the νp 1 / 2 and νf 5 / 2 orbitals in the Ca isotopes appears to be overestimated by the GXPF1A Hamiltonian. ispartof: Physical Review C, Nuclear Physics vol:77 issue:1 status: published

The level structures of 55 Vand 55 Ti, the two nuclei with a single nucleon outside the semi-magic 54 22 Ti 32 core, have been investigated in order to provide new tests of full pf -shell calculations with the GXPF1A interaction. The addition of a proton does not appear to affect the N = 32 shell gap significantly, although comparisons between calculations and experiment at high spins ( I π 21 / 2 − ) indicate the need for a larger model space for an accurate description of the data in this regime. The energy separation between the νp 1 / 2 and νf 5 / 2 orbitals in neutron-rich Ti isotopes is not large enough to result in an N = 34 shell gap. However, comparisons between the 55 Ti data and the calculations argue for the presence of a sizable N = 34 gap in 54 Ca. ispartof: Physics Letters B vol:650 issue:2 pages:135-140 status: published

γ rays from neutron-rich Ti nuclei in the vicinity of N = 32 have been studied at Gammasphere using deep-inelastic reactions induced by 48 Ca beams on thick 208 Pb and 238 U targets. The 53 Ti yrast cascade was identified for the first time, and the location in energy of states with spin up to I = 21/2 was determined. The excitations of 53 Ti provide new tests of effective interactions for full- pf -shell calculations. Comparisons between theory and experiment for the highest spin states in 53 Ti favor the recently proposed GXPF1A interaction, which accounts for the appearance of a neutron subshell closure at N = 32 in Ti isotopes as well as for the lack of a similar subshell closure at N = 34, as predicted by earlier calculations with another interaction ispartof: Physical Review C, Nuclear Physics vol:72 issue:4 status: published

The level structure of 2254Ti32 has been explored for the first time by combining β-decay measurements from fragmentation products with prompt γ-ray spectroscopy following deep inelastic reactions. The latter technique was also instrumental in tracing 52Ti30 to higher spin. The data provide new tests of effective interactions for full pf-shell calculations in neutron-rich nuclei above 48Ca. The data indicate the presence of a significant subshell gap at N = 32 and comparisons between theory and experiment suggest an additional shell closure at N = 34 in Ca and Ti isotopes.