E.F. Aguileraa,b*, E. Martinez–Quiroza, H. García–Martíneza,b, D. Lizcanoa, J. J. Kolatac, L. O. Lammc, G. Rogachevc, P.A. De Youngd, C. Guessd, U. Khadkad, P.J. Mearsd, F.D. Becchettie, Y. Chene, H. Jiange, J.D. Hinnefeldf, and G.F. Peasleeg
a Departamento del Acelerador, Instituto Nacional de Investigaciones Nucleares, Apartado postal 18–1027, 11801, México, D.F., México. * e–mail: efar@nuclear.inin.mx.
b Universidad Autónoma del Estado de México, C.P. 50000, Toluca, México.
c Physics Department, University of Notre Dame, Notre Dame, In, 46556–5670
d Department of Physics and Eng., Hope College, Holland, Mi, 49423–9000
e Physics Department, University of Michigan, Ann Arbor, Mi, 48109–1120
f Physics Department, Indiana University South Bend, South Bend, In, 46694–7111
]]> g Department of Chemistry, Hope College, Holland, Mi, 49423–9000
Recibido el 8 de febrero de 2005
Aceptado el 27 de marzo de 2005
Abstract
Proton angular distributions are measured for the exotic proton–halo nucleus 8B on a 58Ni target. The proton spectra are well described by statistical model calculations using the code PACE if both complete and incomplete fusion are taken into account. Fusion cross sections are deduced by using calculated proton multiplicities, a technique that is first successfully tested with the better known beam 6Li. The resulting fusion excitation function shows a large enhancement that requires a strikingly large barrier radius in order to be described, consistent with the assumption of a proton halo for 8B.
Keywords: Exotic nucleus; proton halo; complete and incomplete fusion.
Resumen
]]> Se midieron las distribuciones de protones producidos en la reacción del núcleo con halo protónico 8B con 58Ni. Si toma en cuenta tanto fusión completa como incompleta, los espectros de protones son bien descritos con el modelo estadístico implementado en el código PACE. Las secciones eficaces de fusión se deducen, usando las multiplicidades predichas. Primero se verificó la validez del método usando, aplicandolo en forma satisfactoria para un proyectil de 6Li. La función de excitación obtenida, presenta un acercamiento grande, que para ser descrito, requiere de un valor sorprendentemente grande del radio de la barrera, lo cual es consistente con la suposición del halo protónico para el 8B.Descriptores: Núcleo exótico; halo protónico; fusión completa e incompleta.
PACS: 25.60.–t;25.60.Pj;25.70.–z
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Acknowledgments
This work has been partially supported by CONACYT (Mexico) and by NSF under Grant Nos. PHY99–01133, PHY98–04869, PHY00–72314, and PHY98–70262. E. F. A. acknowledges the warm hospitality of all personnel at the Notre Dame Nuclear Structure Lab.
]]> References
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