H. Hua

Studies Around A∼100 Using Binary Reactions

The structure of stable and neutron‐rich nuclei with Z∼42 and N∼58 have been studied following binary heavy‐ion reactions between a 136Xe beam and a thin, self‐supporting 100Mo target. Discrete states at spins of 20ℏ and above have been identified and these data allow both gamma‐ray fold and binary‐fragment particle angular distribiution analyses to be made. On the basis of these results, suggestions are made for future directions of this research extending to higher spin states in this region where more exotic nuclear shapes are predicted.

Observation of an isomeric state in {sup 197}Au

Wheldon, C. Valiente-Dobon, J. J. Regan, P. H. Pearson, C. J. Wu, C. Y. Smith, J. F. Macchiavelli, A. O. Cline, D. Chakrawarthy, R. S. Chapman, R. Cromaz, M. Fallon, P. Freeman, S. J. Gelletly, W. Goergen, A. G. Hayes, A. B. Hua, H. Langdown, S. D. Lee, I. Y. Liang, X. Podolyak, Zs. Sletten, G. Teng, R. Ward, D. Warner, D. D. Yamamoto, A. D.

Structure And Decay Of Neutron-Rich Nuclides In The 115 {<=} A {<=} 138 Mass Range And r-Process Nucleosynthesis

The structure and decay of neutron‐rich r‐process nuclides has been studied by a variety of means that take advantage of enhanced selectivity to permit identification of exotic nuclides. New level structures are presented for 134,135Sb along with data for Ag isomers and Cd yrast structures. Some of the properties measured play an important role in calculations of the yields of elements and isotopes produced in r‐process nucleosynthesis that takes place at high temperature in the presence of large densities of neutrons.

Population of 195Os via a deep‐inelastic reaction

The present work reports on the 76195Os isotope, which is the most neutron‐rich osmium isotope for which transitions have been measured. It has been populated following a multi‐nucleon transfer reaction between a thin 78198Pt target and an 850‐MeV 54136Xe beam. Evidence from γ‐ray coincidences has been found for an Iπ = (272−) isomeric state with a measured half‐life of 26 ± 9ns.

Structural Evolution in the (N,Z,Iπ) Coordinate Frame for A∼100

Multinucleon transfer reactions between a thin 100Mo target and a 136Xe beam at an energy of 700 MeV have been used to investigate the evolution of structure with increasing angular momentum in a range of nuclei with A∼100. The use of kinematically complete experiments coupled with isomer tagging allow the selection of specific exit channels. The evolution from quasi‐vibrational states at low spins to quasi‐rotational structures following the population of a low‐Ω, ‘rotationally aligned’ h11/2 neutron configuration is demonstrated to be a standard feature of the region using the so‐called E‐Gamma Over Spin (E‐GOS) empirical prescription. This treatment is extended to odd‐A nuclei.

Structure Of Neutron‐Rich Nuclei In A∼100 Region Observed In Fusion‐Fission Reactions

Neutron‐rich nuclei around A∼100 were populated as fission fragments produced by the 238U(α,f) fusion‐fission reaction. The deexcitation γ rays were detected by Gammasphere in coincidence with the detection of both fission fragments by the Rochester 4π heavy‐ion detector array, CHICO. This technique allows Doppler‐shift corrections to be applied for the observed γ rays on an event‐by‐event basis thus establishing the origin of γ rays from either fission fragment. In addition, it allows observation of γ‐ray transitions from states with short lifetimes and offers the opportunity to study nuclear species beyond the reach of the spontaneous fission process. With these advantages, one can extend the spectroscopic study to higher spins than those derived using the thick‐target technique, and to more neutron‐rich nuclei than those derived from spontaneous fissions. Among the new and interesting phenomena identified in this rapid shape‐changing region, the most distinct result is the evidence for a prolate‐to‐obl...