D. Sohler

Unveiling the Intruder Deformed02+State inSi34

The 02(+) state in 34Si has been populated at the GANIL-LISE3 facility through the β decay of a newly discovered 1(+) isomer in 34Al of 26(1) ms half-life. The simultaneous detection of e(+)e(-) pairs allowed the determination of the excitation energy E(02(+))=2719(3)  keV and the half-life T(1/2)=19.4(7) ns, from which an electric monopole strength of ρ(2)(E0)=13.0(0.9)×10(-3) was deduced. The 2(1)(+) state is observed to decay both to the 0(1)(+) ground state and to the newly observed 0(2)(+) state [via a 607(2) keV transition] with a ratio R(2(1)(+)→0(1)(+)/2(1)(+)→0(2)(+))=1380(717). Gathering all information, a weak mixing with the 0(1)(+) and a large deformation parameter of β=0.29(4) are found for the 0(2)(+) state, in good agreement with shell model calculations using a new SDPF-U-MIX interaction allowing np-nh excitations across the N=20 shell gap.

Structure of high-spin states in Pd-100

High-spin states of the neutron deficient 100 Pd nucleus have been investigated via the 50 Cr( 58 Ni, 4pα )a nd 70 Zn( 36 S,6n) heavy-ion induced reactions. For the detection of evaporated particles and γ rays the NORDBALL array equipped with ancillary detectors and the E UROGAM II detector system were utilized. By the use of in-beam spectroscopic methods 89 transitions belonging to 100 Pd have been observed, 49 of which were identified for the first time. The level scheme has been extended

Nuclear structure study ofN19,21nuclei byγspectroscopy

The structure of neutron-rich nitrogen nuclei has been studied by use of neutron removal reaction and inelastic scattering. Mass and charge deformations have been deduced for the first excited state of 21 N, which indicates the partial persistence of the N = 14 subshell closure in nitrogen isotopes. The spectroscopic information obtained on the structure of 19,21 N confirms the results from a previous experiment.

Nuclear Structure around the N=16 subshell closure

In‐beam gamma‐spectroscopy using fragmentation reactions of both stable and radioactive beams have been performed in order to study the structure of excited states in the neutron‐rich 18,20C, 21–24O and 23,25F isotopes. For the produced fragments, γ‐ray energies, intensities and γγ coincidences have been measured. Based on this information new level schemes are proposed up to the neutron separation energy for some of these isotopes. The systematics of the 2+ energy has been extended up to 20C in the C isotopic chain. Level schemes are suggested for 21O and 22O. The non observation of any γ‐ray from 23O and 24O suggests that their excited states lie above the neutron decay thresholds. The study of F isotopes provides hint of the possible change in nuclear structure between the F and O isotopic chains. These results, together with the size of the N=14 and N=16 shell gaps in C,O,F isotopes are discussed in the framework of shell model calculations.

Maximally aligned states in Ag-99

Abstract:Excited states of 99Ag were populated via the 50Cr + 58Ni (261 MeV) reaction using the NORDBALL detector array equipped with charged-particle and neutron detector systems for reaction channel separation. On the basis of the measured γγ-coincidence relations and angular distribution ratios a significantly extended level scheme has been constructed up to Ex ∼ 7.8 MeV and I = 35/2. The experimental results were described within the framework of the shell model. Candidates for states fully aligned in the πg9/2-3ν(d5/2, g7/2)2 valence configuration space were found at 4109 and 6265 keV.

Neutron excitations across the N=50 shell gap in 102In

The structure of In-102 has been investigated by in-beam gamma-spectroscopic methods. Knowledge on the excited states of this nucleus has significantly been extended. Three cascades of transitions were observed to exceed the spin-energy domain spanned by the pig(9/2)(-1)v(d(5/2),g(7/2))(3) configurations. The new high spin states at similar to 4 MeV excitation energy could be assigned to the pig(9/2)(-1)v(d(5/2), g(7/2))(2)h (11/2) configuration, while at least those at 4.733, 5.192 and 5.853 MeV most likely arise from the vg(9/2) --> vd(5/2), g(7/2) one-particle-one-hole excitation across the N = 50 shell closure.

Nuclear structure studies of

The structure of the

^{24}

^{24}

F

F nucleus has been studied at GANIL using the

Study of 45Ar through (d, p) reaction at SPIRAL

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