Changing source characteristics during multifragment decay

The spatial-temporal extent of the emitting system for central collisions in ⁸⁴Kr + ¹⁹⁷Au at E/A = 35, 55, and 70 MeV is probed using fragment-fragment velocity correlation functions. Selection on fragment pairs of high velocity yields a stronger fragment-fragment Coulomb interaction than for inclusive fragment pairs. This result is consistent with fragment emission from a source of decreased spatial-temporal extent. The universality of this association and the effect of different selection criteria are explored. The sensitivity of the spatial-temporal extent deduced by the correlation function technique to measurement uncertainties, assumed source characteristics, and rotational effects is assessed. {} 1996 The American Physical Society.