  In the domain of Fermi energy, it is extremely complex to isolate
experimentally fragments and particles issued from the cooling of a hot nucleus
produced during a heavy ion collision. This paper presents a new method to
characterize more precisely hot Quasi-Projectiles. It tries to take into
account as accurately as possible the distortions generated by all the other
potential participants in the nuclear reaction. It is quantitatively shown that
this method is a major improvement respect to classic calorimetries used with a
4$\pi$ detector array. By detailing and deconvolving the different steps of the
reconstitution of the hot nucleus, this study shows also the respective role
played by the experimental device and the event selection criteria on the
quality of the determination of QP characteristics.
