  Experimentally the temperature in a Bose--Einstein condensate is always
deduced resorting to the comparison between the Maxwell--Boltzmann velocity
distribution function and the density profile in momentum space. Though a
successful method it is an approximation, since it also implies the use of
classical statistical mechanics at temperatures close to the condensation
temperature where quantal effects play a relevant role. The present work puts
forward a new method in which we use an ultra--intense light pulse and a
nonlinear optical material as detectors for differences in times--of--flight.
This experimental value shall be compared against the result here calculated,
using the Bose--Einstein distribution function, which is a
temperature--dependent variable, and in this way the temperature of the
condensate is obtained.
