V. Werner*, E. Williams*, P. von Brentano** and C. Scholl**
*Wright Nuclear Structure Laboratory, Yale University, New Haven, 272 Whitney Avenue, CT 06520–8124, U.S.A.
**Institut für Kernphysik, Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany.
Recibido el 1 de febrero de 2006
Aceptado el 30 de marzo de 2006
]]> Abstract
An overview of the concept of quadrupole shape invariants is given. Definitions and ways to derive shape invariants from data that were found in recent works are summarized, and the connection and sensitivity of shape invariants to the nuclear shape/phase transition is shown. First results of an ongoing survey of shape invariants for excited states are presented, investigating the critical point behavior as a function of angular momentum and energy. A manifestation of theoretical predictions appears to be found in the transitional Gd isotopes.
Keywords: Electromagnetic transitions; collective levels; collective models.
Resumen
Se presenta una revision del concepto de los invariantes de forma cuadrupolares, sus definiciones y las maneras de extraerlos de los datos experimentales. Se muestra la conexión y sensibilidad de invariantes de forma con las transiciones de fase en la física nuclear. Se discuten los primeros resultados de una investigación de invariantes de fase para estados excitados a través de un estudio del comportamiento del punto crítico como función del momento angular y la energía. Hay evidencia que las predicciones teóricas se manifiestan en los isótopos de Gd.
Descriptores: Transiciones electromagnéticas; excitaciones colectivas; modelos colectivos.
PACS: 23.20.–g, 25.20.Dc; 21.10.Re; 21.60.Ev
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Acknowledgments
For discussions we thank R.F. Casten, F. Iachello, R. Krucken, and E.A. McCutchan. This work was supported by USDOE under grant number DE–FG02–91ER40609, and by DFG under contract Br 799/11–1.
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