M. Serris

High-spin structure of 155Dy

Abstract High-spin states in 155Dy have been studied by γ-γ coincidence measurements via the 124Sn(36S, 5n)155Dy reaction at a beam energy of 155 MeV. Additional information has also been extracted from the reaction 156Gd(3He, 4n)155Dy at 39 MeV beam energy. Eight rotational bands have been populated and observed up to high spin (I⩽ 93 2 ) . The band features have been analysed within the framework of the cranked-shell model. The i 13 2 neutron alignments and the h 11 2 proton alignments are discussed. B(M1)/B(E2) ratios have also been extracted for the strongly coupled bands to deduce further information on the detailed structure of these bands. The highest states (above spin 30) of two of the negative-parity bands gain energy rapidly with respect to a rigid rotor, which is consistent with properties expected for terminating bands.

High spin structures in 194 Hg

High spin states in the isotope194Hg were populated using the150Nd (48Ca,4n) reaction at a beam energy of 213 MeV. The analysis ofγ-γ coincidences has revealed two new structures at excitation energies above 6 MeV and at moderate spin. The two structures are a manifestation of the deviation of nucleus from the collective rotation which dominates its lower excitation behaviour. A comparison with similar structures in the neighbouring Hg isotopes is also attempted.

High spin levels in119Te

High spin levels in119Te have been populated following the96Zr (30Si, α 3n)119Te reaction at a beam energy of 135 MeV. The subsequentγ-ray deexcitation was studied usingγ-ray spectroscopic methods. New levels and several spin and parity assignments up toJπ=55/2− were established. The decay scheme at high-spin exhibits single-particle characteristics associated with the fully aligned ν(h11/2)3 π(g7/2)2 configuration for the 39/2− level, while the 55/2− level could be interpreted as fully aligned π(d5/2)2ν h112/5 g72/−2) configuration.

Isomeric Cross‐Section Study of Neutron‐Induced Reactions on Ge

The 72Ge(n,α)69mZn, 74Ge(n,α)71mZn, 76Ge(n,2n)75g+mGe reaction cross sections have been measured from 9.6 to 11.4 MeV and studied, along with data from literature, within the frame of the statistical model using the code EMPIRE‐II.

Neutron induced reactions at the Athens Tandem Accelerator of NCSR “Demokritos”

In the 5.5 MV tandem T11/25 Accelerator Laboratory of NCSR “Demokritos” monoenergetic neutron beams have been used in the energy range 7–11.5 MeV, produced via the 2H(d,n) reaction. The flux variation of the neutron beam is monitored by using a BF3 detector, while an investigation of the energy dependence of the neutron fluence is carried out via the multiple foil activation technique. The 232Th(n,2n)231Th and 241Am(n,2n)240Am as well as (n,2n), (n,p) and (n,α) reactions on natural Ge and Hf isotopes, have been investigated from threshold up to 11.5 MeV, by using the activation method. The cross section values have been determined relative to the 197Au(n,2n)196Au, 27Al(n,α)24Na and 93Nb(n,2n) reference reaction cross sections.

Neutron activation measurements on natural Ge and Hf

Cross section measurements of neutron induced reactions on isotopes of natural Ge and Hf have been carried out at the 5.5 MV Tandem accelerator of the NCSR “Demokritos” in Athens, Greece, using the activation technique. The measurements have been performed at neutron incident energies 8.8, 9.6, 10.6, 11.1, 11.4 MeV for the case of Ge and at 8.8, 9.6, 11.1, 11.4 MeV for the Hf one. In all cases the target material was Ge and HfO2 powder of high purity.