October 4, 2001
The relationship between nuclear temperature and excitation energy of hot nuclei formed by 8 GeV/c negative pion and antiproton beams incident on 197Au has been investigated with the ISiS 4-pidetector 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-3He/4He) and (d/t-3He/4He) are in agreement below E*/A ~ 7 MeV when corrected for secondary decay. Comparison of these caloric curves to those from other experiments shows some differences that may be attributable to instrumentation and analysis procedures. The caloric curves from this experiment are also compared with the predictions from the SMM multifragmentation model.
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December 2, 1997
Realistic caloric curves are obtained for $^{197}Au + ^{197}Au$ reaction with incident energy ranging from 35 to 130 MeV/nucleon in the dynamic statistical multifragmentation model. It is shown that for excitation energy 3 to 8 MeV/nucleon, the temperature remains constant in the range 5 to 6 MeV, which is close to experiment. The mechanism of energy deposition through the tripartition of colliding system envisaged in this model together with inter-fragment nuclear interactio...
June 25, 1999
Excitation-energy distributions have been derived from measurements of 5.0-14.6 GeV/c antiproton, proton and pion reactions with $^{197}$Au target nuclei, using the ISiS 4$\pi$ detector array. The maximum probability for producing high excitation-energy events is found for the antiproton beam relative to other hadrons, $^3$He and $\bar{p}$ beams from LEAR. For protons and pions, the excitation-energy distributions are nearly independent of hadron type and beam momentum above ...
April 20, 2006
An extensive study of GeV light-ion-induced multifragmentation and its possible interpretation in terms of a nuclear liquid-gas phase transition has been performed with the Indiana Silicon Sphere (ISiS)4 pi detector array. Measurements were performed with 5-15 GeV/c p, pbar, and pion beams incident on $^{197}$Au and 2-5 GeV $^3$He incident on $^{nat}$Ag and $^{197}$Au targets. Both the reaction dynamics and the subsequent decay of the heavy residues have been explored. The da...
January 22, 1998
Breakup temperatures in central collisions of 197Au + 197Au at bombarding energies E/A = 50 to 200 MeV were determined with two methods. Isotope temperatures, deduced from double ratios of hydrogen, helium, and lithium isotopic yields, increase monotonically with bombarding energy from 5 MeV to 12 MeV, in qualitative agreement with a scenario of chemical freeze-out after adiabatic expansion. Excited-state temperatures, derived from yield ratios of states in 4He, 5Li, 6Li, and...
July 8, 1996
We report on temperature measurements of nuclear systems formed in the Au+Au collisions at incident energies of 50, 100, 150, 200 and 1000 A MeV. The target spectator matter was studied at the highest energy and the interacting zone (participants) at the lower ones.The temperature deduced from the isotope ratios was compared with the one deduced via the excited states population. An unexpected disagreement was found between the two measurements.
September 20, 2000
The measurement and interpretation of isotopic yield ratios in heavy ion reactions at intermediate and high energies are discussed and the usefulness of these observables for establishing equilibrium properties and for determining thermodynamic parameters is illustrated. The examples are mainly taken from work performed with lighter projectiles at intermediate and high energies and from studies of spectator reactions at relativistic energies. As an application, the caloric cu...
October 30, 1999
Fragment kinetic energy spectra for reactions induced by 8.0 GeV/c $\rm{\pi^-}$ beams incident on a $\rm{^{197}}$Au target have been analyzed in order to deduce the possible existence and influence of thermal expansion. The average fragment kinetic energies are observed to increase systematically with fragment charge but are nearly independent of excitation energy. Comparison of the data with statistical multifragmentation models indicates the onset of extra collective therma...
April 4, 1997
We report on new measurements of breakup temperatures for target spectators from 197Au + 197Au reactions at 1000 MeV per nucleon. The temperatures rise with decreasing impact parameter from 4 MeV for peripheral to about 10 MeV for the most central collisions, in good agreement with previous results for projectile spectators at 600 MeV per nucleon. The measured temperatures agree quantitatively with the breakup temperatures predicted by the statistical multifragmentation mod...
August 31, 1999
The microcanonical multifragmentation model from [Al. H. Raduta and Ad. R. Raduta, Phys. Rev. C 55, 1344 (1997); 56, 2059 (1997); 59, 323 (1999)] is refined and improved by taking into account the experimental discrete levels for fragments with $A \le 6$ and by including the stage of sequential decay of the primary excited fragments. The caloric curve is reevaluated and the heat capacity at constant volume curve is represented as a function of excitation energy and temperatur...
December 1, 2012
This work focuses on the study of temperature associated with the final heavy fragments in reactions induced by both the neutron-proton symmetric and the neutron-rich projectiles, and with incident energy ranges from 60$A$ MeV to 1$A$ GeV. Isobaric yield ratio (IYR) is used to determine the temperature of heavy fragments. Cross sections of measured fragment in reactions are analyzed, and a modified statistical abrasion-ablation (SAA) model is used to calculate the yield of fr...