Kinetic energy spectra for fragments and break-up density in multifragmentation

We investigate the possibility, in nuclear fragmentation, to extract information on nuclear density at break-up from fragment kinetic energy spectra using a simultaneous scenario for fragment emission. It is found that a decrease of peak centroids for kinetic energy spectra of fragments with increasing excitation energy can be observed at constant low density, which is different from recently published results of Viola et al. [V.E. Viola, K. Kwiatkowski, J.B. Natowitz, S.J. Yennello, Phys. Rev. Lett. 93 (2004) 132701].