Angular momentum in the 6He+209Bi reaction deduced from isomer ratio measurements

P. A. DeYoung, B. Atallah, B. Hughey, P. L. Jolivette, M. Kern, G. F. Peaslee, V. Guimarães, J. J. Kolata, D. Peterson, P. Santi, R. White-Stevens, E. F. Aguilera, E. Martinez-Quiroz, F. D. Becchetti, M. Y. Lee, J. A. Zimmerman, J. D. Hinnefeld, and O. A. Capurro
Phys. Rev. C 62, 047601 – Published 8 September 2000
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Abstract

The angular momentum distribution of the compound nucleus is a fundamental characteristic of the reaction dynamics and can provide insight into reactions involving neutron- or proton-rich projectiles. Specifically, following the fusion of 6He with 209Bi (at center-of-mass energies of 18 to 27 MeV), 212At is formed by the evaporation of three neutrons from the compound nucleus. The decay process leaves the residual 212At in either the ground state (Jπ=1, T1/2=314 ms) or a metastable state (Jπ=9, T1/2=119 ms). The ratio of the number of residual 212mAt to the total number of 212At residual nuclei is sensitive to the original momentum distribution of the compound nucleus. The measured isomer ratio is consistent with that predicted by standard models. This agreement is observed even at the lower energies where the measured three neutron evaporation cross section is greatly enhanced compared to model calculations. While the inclusion of coupling to the neutron-transfer channels improves the agreement with the observed cross-section data somewhat, the predicted isomer ratio then diverges from the measured ratio.

  • Received 15 March 2000

DOI:https://doi.org/10.1103/PhysRevC.62.047601

©2000 American Physical Society

Authors & Affiliations

P. A. DeYoung, B. Atallah, B. Hughey, P. L. Jolivette, M. Kern, and G. F. Peaslee

  • Department of Physics, Hope College, Holland, Michigan 49422-9000

V. Guimarães, J. J. Kolata, D. Peterson, P. Santi, and R. White-Stevens

  • Physics Department, University of Notre Dame, Notre Dame, Indiana 46556-5670

E. F. Aguilera and E. Martinez-Quiroz

  • Departamento del Acelerador, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, C.P. 11801, D.F., Mexico

F. D. Becchetti, M. Y. Lee, and J. A. Zimmerman

  • Physics Department, University of Michigan, Ann Arbor, Michigan 48109

J. D. Hinnefeld

  • Physics Department, Indiana University - South Bend, South Bend, Indiana 46615

O. A. Capurro

  • Laboratorio TANDAR, Departamento de Física, Comisión Nacional de Energía Atómica, (1429) Buenos Aires, Argentina

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Vol. 62, Iss. 4 — October 2000

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