R.M. Clark
Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A.
Recibido el 13 de enero de 2006
Aceptado el 14 de marzo de 2006
Abstract
]]> This paper is divided in two main sections focusing on different aspects of collective nuclear behavior. In the first section, solutions are considered for the collective pairing Hamiltonian. In particular, an approximate solution at the critical point of the pairing transition from harmonic vibration (normal nuclear behavior) to deformed rotation (superconducting behavior) in gauge space is found by analytic solution of the Hamiltonian. The eigenvalues are expressed in terms of the zeros of Bessel functions of integer order. The results are compared to the pairing bands based on the Pb isotopes. The second section focuses on the experimental search for the Giant Pairing Vibration (GPV) in nuclei. After briefly describing the origin of the GPV, and the reasons that the state has remained unidentified, a novel idea for populating this state is presented. A recent experiment has been performed using the LIBERACE+STARS detector system at the 88–Inch Cyclotron of LBNL to test the idea.Keywords: Collective models; pairing; Pb isotopes.
Resumen
Este artículo consiste en dos secciones en las cuales se presentan aspectos diferentes del comportamiento colectivo nuclear. En la primera parte, se consideran soluciones para Hamiltonianos describiendo el apareamiento colectivo. En particular, se discute una solución aproximada para el punto crítico de la transición de apareamiento entre vibraciones armónicas (comportamiento regular) y rotaciones deformadas (comportamiento superconductor). Se hace una comparación con las bandas de apareamiento en los isótopos de Pb. La segunda sección se concentra en la busqueda experimental de la vibración de apareamiento gigante (GPV por sus siglas en inglés) en la física nuclear. Después de haber discutido el origin de la GPV y las razones por las cuales hasta la fecha no ha sido identificada, se presenta una idea novedosa para poblar esta modo de excitación. Recientemiente, se llevó a cabo un experimento con el detector LIBERACE+STARS en el ciclotrón de LBNL para comprobar este método.
Descriptores: Modelos colectivos; apareamiento; isótopos de Pb.
PACS:21.60.–n;21.10.Re
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]]>Acknowledgments
This work has been supported in part by the U.S. DoE under Contract No. DE–AC02–05CH11231 (LBNL). Different parts of this work were performed in close collaboration with A.O. Macchiavelli, L. Fortunato, R. Krucken, and the members of the LIBERACE+STARS collaboration from LLNL and LBNL. I'd also like to thank the operations staff of the 88–Inch Cyclotron.
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