  We propose event by event velocity fluctuations of nuclear fission fragments
as an additional interesting observable that gives access to the nuclear
temperature in an independent way from spectral measurements and relates the
diffusion and friction coefficients for the relative fragment coordinate in
Kramer-like models (in which some aspects of fission can be understood as the
diffusion of a collective variable through a potential barrier). We point out
that neutron emission by the heavy fragments can be treated in effective theory
if corrections to the velocity distribution are needed.
