Heat partition in theE/A=8.5 MeVGe74+165Ho reaction

The excitation-energy distribution of projectilelike fragments formed in the E/A=8.5 MeV ${}_{}{}^{74}{}_{}{}^{}\mathrm{d}$/rGe${+}^{165}$Ho reaction has been obtained by applying a statistical evaporation calculation to the difference between primary fragment mass yields derived from kinematic coincidence measurements and directly measured yields. A gradual transition from approximate equipartition of excitation energy for small energy losses to a division that favors the targetlike fragment for highly damped events is observed, in agreement with previous measurements. For a given energy loss, heat partition is found to correlate with the direction of net nucleon transfer. The variances of the excitation-energy distributions are shown to increase monotonically as a function of energy loss. The average data are compared with predictions of the nucleon exchange transport model. The results suggest that energy-loss mechanisms in addition to nucleon exchange may be important in the early stages of the collision.