Search

The delayed coincidence method with special reference to the in-beam experiments is considered as a means of identification and the lifetime measurements of isomeric states, as well as, the method of the investigation of radiations populating isomeric states. Isomers are detected and correlated with prompt events if they occur within a certain time of the prompt event. The 16O +208Pb reaction was investigated using the OSIRIS-II and the EAGLE arrays at HIL-UW. About eighty nuclei were identified as fission fragments among the reaction products. Several known isomeric transitions associated with reaction products in neutron-rich nuclei region were detected, as well as some new candidates were observed. [ABSTRACT FROM AUTHOR]

Low-lying 0+ states, close in energy to the first excited 2+ state, have been observed in even--even molybdenum isotopes, indicating shape coexistence in these nuclei. Results of our previous Coulomb excitation measurements of 96Mo and 98Mo supported the shape coexistence scenario. A series of Coulomb excitation experiments to study the neighboring stable 100Mo isotope was performed on beams of the Warsaw Cyclotron. During the re- cent experiment with 100Mo target the new dedicated set-up for Coulomb excitation measurements was used at HIL. First results are presented. The performance of the new detection system opens promising possibilities for future Coulomb excitation experiments. [ABSTRACT FROM AUTHOR]

The beam pulse structure of the HIL cyclotron and thick target γ - γ co-incidence measurements in the in-beam and off-beam modes have been used to search for isomers in the A &asymph; 120 mass region using heavy-ion reactions. The half-life of the 2721 keV, (25/2+) level in 121Sb was determined in the off-beam mode to be 167 ± 19 µs. Two deexcitation sequences of this isomer are proposed. The isomeric state is considered to be of 3-quasiparticle nature π(d5/2)ν(h²11/2)10+. [ABSTRACT FROM AUTHOR]

The lifetime of levels in 128Cs and 132La have been measured in-beam of the Warsaw University Cyclotron using DSA method. The absolute M1 and E2 transition probabilities have been deduced. Two cases have been found: 132La where the B(E2) values in yrast and partner bands differ up to 30 times and 128Cs - the B(E2) values in both bands differ only few times. It seems that bands in 128Cs are better candidates for chiral partner bands than the ones in 132La. [ABSTRACT FROM AUTHOR]

Coulomb excitation experiment of 100Mo has recently been performed using 40Ar beam from the Warsaw Cyclotron. Three lowest 2+ states, two 4+ and one 0+ excited states have been observed. It is a continuation of the systematic study of 96Mo and 98Mo nuclei having low lying 0+ excited state, with energy very close to the first 2+ state. [ABSTRACT FROM AUTHOR]

The Coulomb excitation experiment to study electromagnetic properties of the heaviest stable Mo isotope, 100Mo, was performed using a 76 MeV 32S beam from the Warsaw cyclotron U-200P. Magnitudes and relative signs of 26 E1, El, E3, and M1 matrix elements coupling nine low-lying states in 100Mo were determined using the least-squares code GOSIA. Diagonal matrix elements (related to the spectroscopic quadrupole moments) of the 2f1+, 22+, and 23+ states as well as the 41+ state were extracted. The resulting set of reduced E2 matrix elements was complete and precise enough to obtain, using the quadrupole sum rules approach, quadrupole deformation parameters of 100Mo in its two lowest 0+ states: ground and excited. The overall deformation of the 0¹ and 0² states in 100Mo is of similar magnitude, in both cases larger compared to what was found for the neighboring isotopes 96Mo and 98Mo. At the same time, the asymetry parameters obtained for both states strongly differ, indicating a triaxial shape of the 100Mo nucleus in the ground state and a prolate shape in the excited 0+ state. Low-energy quadrupole excitations of the 100Mo nucleus were studied in the frame of the general quadrupole collective Bohr Hamiltonian model (GBH). The potential energy and inertial functions were calculated using the adiabatic time-dependent Hartree-Fock-Bogoliubov (ATDHFB) method starting from two possible variants of the Skyrme effective interaction: SHI and Sly4. The overall quadrupole deformation parameters resulting from the GBH calculations with the SLy4 variant of the Skyrme interaction are slightly closer to the experimentally obtained values than those obtained using SUI. [ABSTRACT FROM AUTHOR]