Showing papers by "R. Wadsworth published in 2004"

GEANT Monte Carlo simulations for the GREAT spectrometer

Abstract: GEANT Monte Carlo simulations for the recently developed GREAT spectrometer are presented. Some novel applications of the spectrometer for γ -ray, conversion-electron and β -decay spectroscopy are discussed. The conversion-electron spectroscopy of heavy nuclei with strongly converted transitions and the extension of the recoil decay tagging method to β -decaying nuclei are considered in detail.

αdecay and recoil decay tagging studies ofTl183

Abstract: High-spin states in the nucleus {sup 183}Tl have been studied using the recoil decay tagging and recoil tagging techniques. The data have enabled new structures to be identified which are believed to be based on prolate f{sub 7/2}, h{sub 9/2}, and oblate h{sub 9/2} configurations. In addition, the prolate i{sub 3/2} structure has also been extended. The systematics of the newly identified structures will be discussed. The {alpha} decay of {sup 183}Tl has also been investigated. Examination of both delayed and prompt {gamma} rays in coincidence with the prominent 6333-keV {alpha} decay, together with an investigation of the effects of the summing of L electrons, allow assignment of transitions and the construction of tentative low-spin decay schemes for {sup 179}Au and {sup 175}Ir.

High-spin spectroscopy and quasiparticle alignments in 124,125Ce

Abstract: Rotational bands have been studied to high spins in the neutron-deficient $^{124,125}\mathrm{Ce}$ nuclei The nuclei were populated using the $^{64}\mathrm{Zn}(^{64}\mathrm{Zn},2p2n)^{124}\mathrm{Ce}$ and $^{64}\mathrm{Zn}(^{64}\mathrm{Zn},2pn)^{125}\mathrm{Ce}$ reactions, with a beam energy of $260\phantom{\rule{03em}{0ex}}\text{MeV}$ High-fold $\ensuremath{\gamma}$-ray coincidence data were collected using the Gammasphere germanium-detector array The Microball charged-particle detector array was used to provide channel selection The previously established level structures of both $^{124,125}\mathrm{Ce}$ have been extended to high spins $(\ensuremath{\sim}30\ensuremath{\hbar})$ In addition, several new bands have been identified The alignments of pairs of ${h}_{11∕2}$ neutrons and protons are observed in both nuclei The alignments are compared to the predictions of Woods-Saxon cranked shell model calculations and to the systematics of ${h}_{11∕2}$ quasiparticle alignments in neighboring nuclei The apparent ability of the cranked shell model to explain the ${h}_{11∕2}$ neutron alignments in $^{124,125}\mathrm{Ce}$ highlights the previously reported discrepancies between experiment and theory for the $^{128}\mathrm{Ce}$ isotope and, to a lesser extent, $^{126}\mathrm{Ce}$

High-spin study of rotational structures in 72 Br

Abstract: High-spin states in Br-72(35)37 were studied using the Ca-40(Ar-36,3pn) reaction The existing level scheme has been significantly modified and extended Evidence has been found for a spin reassignment of -1h to the previously observed negative-parity band, which carries implications for the interpretation of a signature inversion in this structure One signature of the previously assigned positive-parity band is interpreted as negative parity and has been extended to I-pi=(22(-)) and its signature partner has been observed up to I-pi=(19(-)) for the first time The remaining positive-parity band has been extended to I-pi=(29(+)) A sequence of states observed to I-pi=(22(+)) may be the signature partner of this structure Configurations have been assigned to each of these three structures through comparisons to cranked Nilsson-Strutinsky calculations (Less)

First identification of {gamma}-ray transitions in {sup 107}Te

Abstract: Gamma-ray transitions in {sup 107}Te have been identified for the first time. The experiment, which utilized the recoil decay tagging technique, was performed at the accelerator laboratory of the University of Jyvaeskylae, Finland. Prompt gamma rays produced in {sup 58}Ni({sup 52}Cr,3n){sup 107}Te{sup *} reactions were detected by the JUROGAM {gamma}-ray spectrometer. The gamma rays belonging to {sup 107}Te were selected based on the recoil identification provided by the RITU gas-filled recoil separator and the GREAT focal plane spectrometer. A first excited state at 90 keV, tentatively of g{sub 7/2} character, is proposed.

Chirality in the A∼100 region

Abstract: Evidence for chirality in nuclei has been found in N ∼ 75 isotopes in the A ∼ 130 mass region. This phenomenon is a signature of triaxiality in nuclei and there is a clear need to study other regions of the Segre chart to see if further examples can be found. Potential Energy Surface (PES) calculations suggest that the N ∼ 57–63, Z ∼ 43–45 region is another promising island of triaxiality. The present experimental study with the Euroball γ‐ray array, using the reaction 96Zr(13C, p2n) at 51 MeV is aimed to search for chirality in 106Rh. Channel selection of 106Rh was done using the charged‐particle array DIAMANT. The yrast level scheme, studied previously in fusion‐fission work, has been confirmed and extended in the present study. In addition, a new strongly coupled band, lying at an excitation energy of ∼ 300 keV above the yrast band, has been found. The two structures show the characteristic properties of the chiral phenomenon.