Comparison of 1A GeV Au-197+C data with thermodynamics: The nature of the phase transition in nuclear multifragmentation - art. no. 054602

Citation
Rp. Scharenberg et al., Comparison of 1A GeV Au-197+C data with thermodynamics: The nature of the phase transition in nuclear multifragmentation - art. no. 054602, PHYS REV C, 6405(5), 2001, pp. 4602
Citations number
82
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
PHYSICAL REVIEW C
ISSN journal
0556-2813 → ACNP
Volume
6405
Issue
5
Year of publication
2001
Database
ISI
SICI code
0556-2813(200111)6405:5<4602:CO1GAD>2.0.ZU;2-#
Abstract
Multifragmentation MF results from 1A GeV Au on C have been compared with t he Copenhagen statistical multifragmentation model (SMM). The complete char ge, mass, and momentum reconstruction of the Au projectile was used to iden tify high momentum ejectiles leaving an excited remnant of mass A, charge Z , and excitation energy E* which subsequently multifragments. Measurement o f the magnitude and multiplicity (energy) dependence of the initial free vo lume 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 fragmen t charge yield distributions, fragment multiplicity distributions, caloric curve, critical exponents, and the critical scaling function are explored i n this comparison. The two stage structure of SMM is used to determine the effect of cooling of the primary hot fragments. Average fragment yields wit h Z greater than or equal to3 are essentially unaffected when the excitatio n energy is less than or equal to7 MeV/nucleon. SMM studies suggest that th e experimental critical exponents are largely unaffected by cooling and eve nt mixing. The nature of the phase transition in SMM is studied as a functi on of the remnant mass and charge using the microcanonical equation of stat e. For light remnants A less than or equal to 100, backbending is observed indicating negative specific heat, while for A less than or equal to 170 th e effective latent heat approaches zero. Thus for heavier systems this tran sition can be identified as a continuous thermal phase transition where a l arge nucleus breaks up into a number of smaller nuclei with only a minimal release of constituent nucleons. Z less than or equal to2 particles are pri marily emitted in the initial collision and after MF in the fragment deexci tation process.