Comparison of1AGeV197Au+Cdata with t

Abstract

Multifragmentation MF results from 1A GeV Au on C have been compared with the Copenhagen statistical multifragmentation model ͑SMM͒. The complete charge, mass, and momentum reconstruction of the Au projectile was used to identify high momentum ejectiles leaving an excited remnant of mass A, charge Z, and excitation energy E* which subsequently multifragments. Measurement of the magnitude and multiplicity ͑energy͒ dependence of the initial free volume and the breakup volume determines the variable volume parametrization of SMM. Very good agreement is obtained using SMM with the standard values of the SMM parameters. A large number of observables, including the fragment charge yield distributions, fragment multiplicity distributions, caloric curve, critical exponents, and the critical scaling function are explored in this comparison. The two stage structure of SMM is used to determine the effect of cooling of the primary hot fragments. Average fragment yields with Zу3 are essentially unaffected when the excitation energy is р7 MeV/nucleon. SMM studies suggest that the experimental critical exponents are largely unaffected by cooling and event mixing. The nature of the phase transition in SMM is studied as a function of the remnant mass and charge using the microcanonical equation of state. For light remnants Aр100, backbending is observed indicating negative specific heat, while for Aу170 the effective latent heat approaches zero. Thus for heavier systems this transition can be identified as a continuous thermal phase transition where a large nucleus breaks up into a number of smaller nuclei with only a minimal release of constituent nucleons. Zр2 particles are primarily emitted in the initial collision and after MF in the fragment deexcitation process.

Theoretical study of projectile fragmentation in theSn112+Sn112and<

“…[8]] is a useful tool for describing the fragment production in peripheral heavy-ion collisions at high energy [6,10,11,18]. In the present work, we consider the ensemble approach with the same parameters that were used for the interpretation of the ALADIN data [6].…”

“…[8,21,22] is used. It represents the main version used previously for successful comparisons with a variety of experimental data [6,10,11,18,[23][24][25]. We calculate the contributions of all breakup channels partitioning the system into various species.…”

Experimental reconstruction of excitation energies of primary hot isotopes in heavy ion collisions near the Fermi energy

“…An accurate modeling of these processes is not simple. Global features of the characteristic experimental observables, such as multiplicities, mass or charge distributions, and energy spectra or the mean energy of the fragments, have been well reproduced by both statistical multifragmentation models, such as microcanonical Metropolitan Monte Carlo model (MMMC) [1,2] and the statistical multifragmentation model (SMM) [2][3][4][5][6][7][8][9][10], and by transport-based models, such as antisymmetrized molecular dynamics (AMD) [11][12][13][14][15][16][17][18], stochastic mean field model (SMF) [19][20][21], and Improved quantum statistical model (ImQMD) [22][23][24][25][26], although they are based on quite different assumptions. The statistical models utilize a freeze-out concept.…”

Multiplicity derivative: A new signature of a first-order phase transition in intermediate-energy heavy-ion collisions

“…Most past investigations have suffered from ambiguity. An example was trying to fit an individual M a to a −τ f (a σ (T −T c )) [13][14][15][16][17]. Equally acceptable but quite approximate fits were found with very different models so no conclusions could be made.…”