Cooling dynamics in multi-fragmentation processes

¹ National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University - East Lansing, MI 48824, USA
² Department of Physics, University of Wisconsin - Madison, WI 53706, USA
³ Instituto de Fisica, Universidade Federal do Rio de Janeiro Cidade Universitária, CP 68528, 21941-972 Rio de Janeiro, Brazil
⁴ Department of Chemistry and IUCF, Indiana University Bloomington, IN 47405, USA
⁵ Department of Chemistry, Washington University St. Louis, MO 63130, USA

Received: 16 February 2006
Accepted: 10 April 2006

Abstract

Fragment energy spectra of neutron-deficient isotopes are significantly more energetic than those of neutron-rich isotopes of the same element. This trend is well beyond what can be expected for the bulk multi-fragmentation of an equilibrated system. It can be explained, however, if some of these fragments are emitted earlier through the surface of the system while it is expanding and cooling.