Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298151
Title: K-isomerism at high-spin beyond the fusion limit
Author: Wheldon, Carl
ISNI:       0000 0001 3566 6628
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 1999
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Abstract:
New high-K isomers have been populated in Ta and W by bombarding thick targets with pulsed 238U beams at 1600 MeV. The new inelastically excited multi-quasiparticle states include Kpi = 21/2- and 29/2- 3-quasiparticle isomers in 181Ta and Kpi = 7- and (16+) isomers in 186W. The Kpi = (16+) state in 186w has t1/2≥3 ms and extends the 4-quasiparticle isomer systematics beyond the limit accessible with fusion-evaporation reactions, using stable beams and targets, for the first time. In addition, a t1/2≥1 ms 3-quasiparticle isomeric state feeding a strongly coupled rotational band has been populated in Ta by nucleon transfer. The excitation energies of the intrinsic states are compared to predictions of blocked BCS calculations. A different study of high-K states used a radioactive 14C beam at 67 MeV to investigate the high-spin structure of Os. New rotational bands built on multi-quasiparticle states with Kpi = 5-, 7-, 9-, 10+ and 15+ are observed. The first crossing of the ground-state band at I = 14 h, is interpreted as involving a high-K t-band structure and explained using a two-band mixing model. The structure at higher angular momentum is dominated by intrinsic states, that exhibit a dramatic loss of isomerism. Potential-energy-surface calculations, with Lipkin-Nogami pairing, show these configurations to be triaxial, accounting for the breakdown in K conservation. The relation between the K projection and the total angular momentum is investigated for these non-axial states.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.298151  DOI: Not available
Keywords: TANTALUM 181 TARGET; TUNGSTEN 186 TARGET; URANIUM 238 REACTIONS; GEV RANGE 01-10; HIGH SPIN STATES; ISOMERIC NUCLEI; OSMIUM 186 TARGET; ROTATIONAL STATES
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