The characteristics of intermediate mass fragments (IMFs: 3<=Z<=20) produced in mid-peripheral and central collisions are compared. We compare IMFs detected at mid-velocity with those evaporated from the excited projectile-like fragment (PLF*). On average, the IMFs produced at mid-velocity are larger in atomic number, exhibit broader transverse velocity distributions, and are more neutron-rich as compared to IMFs evaporated from the PLF*. In contrast, comparison of mid-velocity fragments associated with mid-peripheral and central collisions reveals that their characteristics are remarkably similar despite the difference in impact parameter. The characteristics of mid-velocity fragments are consistent with low-density formation of the fragments. Neutron deficient isotopes of even Z elements manifest higher kinetic energies than heavier isotopes of the same element for both PLF* and mid-velocity emission. This result may be due to the decay of long-lived excited states in the field of the emitting system.
@article{arxiv.nucl-ex/0501022,
title = {Comparison of mid-velocity fragment formation with projectile-like decay},
author = {S. Hudan and R. Alfaro and B. Davin and Y. Larochelle and H. Xu and L. Beaulieu and T. Lefort and R. Yanez and R. T. de Souza and R. J. Charity and L. G. Sobotka and T. X. Liu and X. D. Liu and W. G. Lynch and R. Shomin and W. P. Tan and M. B. Tsang and A. Vander Molen and A. Wagner and H. F. Xi},
journal= {arXiv preprint arXiv:nucl-ex/0501022},
year = {2009}
}