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[en] Excited states of neutron-rich nucleus ⁸²Ge were studied from the spontaneous fission of ²⁵²Cf. Eleven new transitions and seven new levels in ⁸²Ge were identified by using X(Dy)-γ-γ and γ-γ-γ triple coincidences. Possible excited deformed rotational bands are observed, for the first time, in this nuclear region. Coexistence of the spherical ground and deformed excited shapes is proposed in ⁸²Ge. These deformed rotational bands can be formed by two-particle, two-hole excitations with the 0⁺ pairing energy states of the ν9/2[404]^-2 x 1/2[431]² configuration across the N=50 closed shell.

[en] High spin states are observed for the first time in the neutron-rich nuclei ^151,153Pr, ¹⁵⁷Sm, and ⁹³Kr from the spontaneous fission of ²⁵²Cf. Twenty new transitions in ¹⁵¹Pr, twelve in ¹⁵³Pr, five in ¹⁵⁷Sm, and four in ⁹³Kr were identified by using x-ray(Pr/Sm)-γ-γ and γ-γ-γ triple coincidences. From the measured total internal conversion coefficients α_T of four low-energy transitions in ^151,153Pr, we determine that two bands in each nucleus have opposite parity. The interlacing E1 transitions between the bands suggest a form of parity doubling in ^151,153Pr. New bands in ¹⁵⁷Sm and ⁹³Kr are reported. The half-life of the 354.8 keV state in ⁹³Kr is measured to be 10(2) ns.

[en] The results of the experiments aimed at the synthesis of Fl isotopes in the ²³⁹Pu + ⁴⁸Ca and ²⁴⁰Pu + ⁴⁸Ca reactions are presented. The experiment was performed using the Dubna gas-filled recoil separator at the U400 cyclotron. In the ²³⁹Pu+⁴⁸Ca experiment one decay of spontaneously fissioning ²⁸⁴Fl was detected at 245-MeV beam energy. In the ²⁴⁰Pu+⁴⁸Ca experiment three decay chains of ²⁸⁵Fl were detected at 245 MeV and four decays were assigned to ²⁸⁴Fl at the higher ⁴⁸Ca beam energy of 250 MeV. The α-decay energy of ²⁸⁵Fl was measured for the first time and decay properties of its descendants ²⁸¹Cn, ²⁷⁷Ds, ²⁷³Hs, ²⁶⁹Sg, and ²⁶⁵Rf were determined more precisely. The cross section of the ²³⁹Pu(⁴⁸Ca,3 n )²⁸⁴Fl reaction was observed to be about 20 times lower than those predicted by theoretical models and 50 times less than the value measured in the 244Pu+⁴⁸Ca reaction. The cross sections of the ²⁴⁰Pu(⁴⁸Ca,4-3 n )²⁸⁴,²⁸⁵Fl at both ⁴⁸Ca energies are similar and exceed that observed in the reaction with lighter isotope ²³⁹Pu by a factor of 10. The decay properties of the synthesized nuclei and their production cross sections indicate rapid decrease of stability of superheavy nuclei with departing from the neutron number N=184 predicted to be the next magic number. (paper)

[en] It has been shown that there are significant deviations from the expected U(5) dynamical symmetry for ^{110,112,114,116}Cd. However, there is very significant mixing with intruder states in this region. In this paper, we investigated states in the heavier ^120,124,126Cd populated via beta decay. These nuclei exhibit similar patterns to the lighter Cd isotopes even though the intruder states are much higher in energy.

[en] Analysis of high statistics triple coincidence fission γ data from ²⁵²Cf at Gammasphere including angular correlations yielded well-expanded high-spin level schemes with more complete and reliable spin/parity assignments for ⁸²Ge, ^118,120,122Cd and ^114,115Rh. Both the quasi-particle/hole couplings and quasi-rotational degrees of freedom are implied to play roles in these Cd isotopes. Evidence for triaxial shapes and octupole components in the Cd isotopes is presented. These Cd isotopes may have triaxial deformations. High-spin level schemes of ^114,115Rh have been established for the first time. The existence of a relatively large signature splitting and an yrare band shows typical features of a triaxially deformed nucleus. Possible excited deformed rotational bands are observed, for the first time, in ⁸²Ge. From the multipole mixing ratio measurement, the ground state configurations of ^109,111Ru, as well as excited states in ^103,107Mo and ¹¹¹Ru were determined

[en] High-spin excited states in the neutron-rich nucleus ¹¹⁵Rh have been identified for the first time by studying prompt γ rays from the spontaneous fission of ²⁵²Cf with the Gammasphere detector array. A new yrast band and a sideband are built in ¹¹⁵Rh. This level scheme is proposed to be built on the 7/2⁺ ground state. The existence of a large signature splitting and an yrare band in ¹¹⁵Rh shows typical features of a triaxially deformed nucleus. The rigid triaxial rotor plus particle model is used to interpret the level structure of ¹¹⁵Rh. The level energies, the γ branching ratios, the large signature splitting in the yrast band, and the inverted signature splitting in the yrare band in ¹¹⁵Rh are reproduced very well. Strong K mixing occurs in ¹¹⁵Rh at high spin.

[en] The odd-odd neutron-rich nucleus ¹⁵²Pr has been studied from the spontaneous fission of ²⁵²Cf with Gammasphere. A high-spin level scheme of ¹⁵²Pr has been established for the first time. Angular correlation and internal conversion coefficient measurements are used to determine the transition multipolarities. The possible configurations of the bandhead have been discussed based on systematics and total Routhian surface calculations.

[en] High-spin excited states in the very neutron-rich nucleus ¹¹⁴Rh have been studied by examining the prompt γ rays emitted in the spontaneous fission of ²⁵²Cf with the Gammasphere detector array. A high-spin level scheme of ¹¹⁴Rh has been established for the first time with 13 new levels. The level scheme is proposed to be built on a 7^- state. The existence of a relatively large signature splitting and an yrare band show features which may indicate triaxial deformation. The phenomenon of signature inversion has been observed in ¹¹⁴Rh at I=12 (ℎ/2π). The observed signature inversion of ¹¹⁴Rh is interpreted successfully in terms of the triaxial projected shell model. Theoretical calculations suggest that the negative-parity, yrast band of ¹¹⁴Rh has the two-quasi-particle configuration of πg_9/2 x νh_11/2, consistent with the systematics of odd-odd Rh isotopes. The signature inversion at spin 12 (ℎ/2π) may be attributed to the change of rotational mode, from quasi-particle aligned rotation at low spins to collective rotation at high spins.