J. Gizon

In-band M1 and E2 transition rates and collective structures in 128Ba

Abstract Subpicosecond mean lifetimes of eight excited states in 128Ba populated via the 96Zr(36S,4n) reaction were measured by the Doppler-shift attenuation (DSA) technique using a line-shape analysis. The differential decay-curve method (DDCM) was applied for the lifetime determination. The B(E2) values in the yrast band indicate that the first band-crossing is with a proton S-band. The configuration πh 11 2 d 5 2 of the negative-parity semi-decoupled bands is confirmed by the measured B(E2, I → I − 2) and B(M1, I → I − 1) transition strengths. The higher-lying “dipole” band in 128Ba can be described as a high-K four-quasiparticle band built on the prolate configuration (πh 11 2 d 5 2 ) ⊗ (νh 11 2 g 7 2 ) .

Conversion electron measurements in the124Laβ-decay. Spin and parity assignments in124Ba

Low-lying energy levels in124Ba have been investigated from124Laβ-decay by using He-jet technique. Spin and parity assignments have been deduced from internal conversion electron measurements. Aβ-vibrational band based on a second 0+ state has been identified. Experimental level energies have been compared with IBFA-2 calculations.

Identification and structure of yrast levels in theN=89 odd-odd158Tm nucleus

Excited levels have been identified in the odd-odd158Tm nucleus produced in the150Sm (14N,6n) reaction. The observed level structure based on an isomeric state (T1/216±4 ns) is interpreted as a rotational aligned band.

Collective band structures and particle alignments in 124Ba, 125Ba and 125Cs

Abstract High-spin states of 124Ba, 125Ba and 125Cs have been populated in the reactions 110Cd + 18O at 80MeV and 96Zr + 34S at 160 MeV and studied using nuclear spectroscopy techniques. Several bands have been established in 124Ba and previously known band structures in125Ba and 125Cs extended up to ( 43 2 − ) levels. Results concerning crossing frequencies and quasiparticle configurations are deduced from experimental routhians and aligned angular momenta. We propose that the two positive-parity bands in 124Ba are generated by h 11 2 proton and h 11 2 neutron alignments and the three negative-parity bands by the coupling of h 11 2 , g 7 2 neutrons and h 11 2 , g 7 2 or g 9 2 protons.

Level structures of 119,121Xe excited in (12C, 3nγ) reactions and analysis of the h112 bands in the IBF model

Abstract Levels in 119, 121 Xe excited by the reactions 110, 112 Cd( 12 C, 3nγ) 119, 121 Xe have been studied by in-beam γ-ray spectroscopic techniques. Several bands have been observed: h 11 2 and g 7 2 in 119, 121 Xe , a decoupled one in 121 Xe. A new level structure in 119 Xe found for the first time is assigned as the g 9 2 band generated by one hole in the g 9 2 neutron shell. The connections between these bands have been fixed in both nuclei. A detailed analysis is made for the h 11 2 level structure. An interpretation is given in terms of the interacting boson-fermion model where h 11 2 , f 7 2 and h 9 2 fermion configurations are included.

High-spin study of 128Ce and systematics of quasiparticle pair alignment

Abstract High-spin states have been studied in 128 Ce, produced in the 100 Mo( 32 S,4n) reaction, using the Euroball γ -ray spectrometer. A quadruples analysis ( γ 4 ) of the data has extended several bands to high spin. Systematics of quasiparticle alignments in cerium isotopes and relevant isotonic chains are discussed and compared to Woods–Saxon cranking calculations.

Identification and decay of102In, new neutron deficient isotope close to100Sn

Abstract102In, [T1/2=(24±4)s], has been identified for the first time using an on-line mass isotopic separator operating on nuclear reactions induced by heavy ions. Gamma-rays observed both in102In→102Cd decay and in-beam measurements allow to build a partial level scheme for102Cd. Systematics of the two first excited states of even cadmium isotopes shows the special behaviour of the lightest one.

Niveaux de 165Tm atteints dans la réaction 165Ho(α, 4nγ)165Tm

Abstract The γ-rays following the 165Ho(α, 4nγ)165Tm reaction have been studied with Ge(Li) detectors. By means of γ-γ coincidences the rotational bands built on the 1 2 + [411], 7 2 + [404], 7 2 − [523] and 1 2 − [541] intrinsic states are identified.

Alignments and band termination in99,100Ru

Abstracth11/2 neutron and g9/2 proton alignments in99,100Ru deduced from comparisons of experimental Routhians and aligned angular momenta to cranking model calculations. There is indication of band termination in100Ru.

In-beam spectroscopic studies of the nucleus 105Cd

Abstract High spin states in 105Cd have been studied using reactions 106Cd(p, pn), 106Cd(3He, 2p2n), 92Zr(16O, 3n) and 76Ge(34S, 5n). The excited levels are dominated by a negative parity band structure up to spin 47 2 − and a positive parity structure up to spin 27 2 + . The negative parity structure is based on ν h 11 2 excitations and undergoes a band crossing at h ω ≈ 0.44 MeV . This band crossing is interpreted as an alignment of a g 7 2 neutron pair. The positive parity excitations are understood as due to ν g 7 2 and ν d 5 2 configurations. The results are discussed in terms of spin diabatic surface calculations.