Caloric curve of 8 GeV/c negative pion and antiproton + Au reactions

The relationship between nuclear temperature and excitation energy of hot nuclei formed by 8 GeV/c negative pion and antiproton beams incident on Au-197 has been investigated with the ISiS 4pi detector array at the BNL AGS accelerator. The double-isotope-ratio technique was used to calculate the temperature of the hot system. The two thermometers used, (p/d-He-3/He-4) and (d/t-He-3/He-4), are in agreement below E*/Asimilar to8 MeV when corrected for secondary decay. Caloric curves derived from successive segments of the H and He kinetic energy spectra show a systematic decrease in temperature as the kinetic energy bin decreases, consistent with "cooling curve" behavior. When extrapolated to the evaporative-peak region, these results provide good agreement with caloric curves measured for similar systems. The caloric curves from this experiment are also compared with the predictions from the SMM multifragmentation model.