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By using freeze-out properties of multifragmenting hot nuclei produced in quasifusion central $^{129}$Xe+$^{nat}$Sn collisions at different beam energies (32, 39, 45 and 50 AMeV) which were estimated by means of a simulation based on…

Nuclear Experiment · Physics 2022-11-21 B. Borderie , S. Piantelli , J. D. Frankland , N. Le Neindre

An experimental indication of negative heat capacity in excited nuclear systems is inferred from the event by event study of energy fluctuations in $Au$ quasi-projectile sources formed in $Au+Au$ collisions at 35 A.MeV. The excited source…

Simulations based on experimental data obtained from multifragmenting quasi-fused nuclei produced in central $^{129}$Xe + $^{nat}$Sn collisions have been used to deduce event by event freeze-out properties in the thermal excitation energy…

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…

Nuclear Theory · Physics 2009-10-31 Al. H. Raduta , Ad. R. Raduta

Recent important progress on the knowledge of multifragmentation and phase transition for hot nuclei, thanks to the high detection quality of the INDRA array, is reported. It concerns i) the radial collective energies involved in hot…

Heat capacities of model systems with finite numbers of effective degrees of freedom are evaluated using canonical and microcanonical thermodynamics. Discrepancies between both approaches, which are observed even in the infinite-size limit,…

Quantum Physics · Physics 2017-02-16 Pavel Cejnar , Pavel Stránský

It is shown that negative heat capacity in nanoclusters is an artifact of applying equilibrium thermodynamic formalism on a small system trapped out of equilibrium in a particular structural motif representing only part of the energetically…

Materials Science · Physics 2007-05-23 Karo Michaelian , Ivan Santamaria-Holek

The heat capacity of iron isotopes is calculated within the interacting shell model using the complete $(pf+0g_{9/2})$-shell. We identify a signature of the pairing transition in the heat capacity that is correlated with the suppression of…

Nuclear Theory · Physics 2009-11-06 S. Liu , Y. Alhassid

Systems with long-range as well with short-range interactions should necessarily have a convex entropy S(E) at proper phase transitions of first order, i.e. when a separation of phases occurs. Here the microcanonical heat capacity c(E)=…

Statistical Mechanics · Physics 2007-05-23 D. H. E. Gross

Simulations based on experimental data obtained from multifragmenting quasifused nuclei produced in central 129Xe + natSn collisions have been used to deduce event by event freeze-out properties on the thermal excitation energy range 4-12…

Level densities for 93-98Mo have been extracted using the (3He,alpha gamma) and (3He,3He' gamma) reactions. From the level densities thermodynamical quantities such as temperature and heat capacity can be deduced. Data have been analyzed by…

Heat capacities of Na_N, N = 13, 20, 55, 135, 142, and 147, clusters have been investigated using a many-body Gupta potential and microcanonical molecular dynamics simulations. Negative heat capacities around the cluster melting-like…

Atomic and Molecular Clusters · Physics 2016-09-08 Juan A. Reyes-Nava , Ignacio L. Garzon , Karo Michaelian

A general discussion is made concerning the ways in which one can get signatures about a possible liquid-gas phase transition in nuclear matter. Microcanonical temperature, heat capacity and second order derivative of the entropy versus…

Nuclear Theory · Physics 2009-11-07 Al. H. Raduta , Ad. R. Raduta

The density profile of a hot nuclear system produced in intermediate energy heavy ion collisions is studied in a microcanonical formulation with a momentum and density dependent finite range interaction. The caloric curve and the density…

Nuclear Theory · Physics 2008-11-26 S. K. Samaddar , J. N. De , X. Vinas , M. Centelles

The dynamics and thermodynamics of phase transition in hot nuclei are studied through experimental results on multifragmentation of heavy systems (A>200) formed in central heavy ion collisions. Different signals indicative of a phase…

We consider a soluble model of multifragmentation which is similar in spirit to many models which have been used to fit intermediate energy heavy ion collision data. In this model $c_v$ is always positive but for finite nuclei $c_p$ can be…

Nuclear Theory · Physics 2009-11-10 C. B. Das , S. Das Gupta , A. Z. Mekjiani

Anomalous negative heat capacities have been claimed as indicators of first order phase transitions in finite systems in general, and fornuclear systems in particular. A thermodynamic approach allowing for all Q value terms is used to…

Nuclear Theory · Physics 2014-11-18 L. G. Moretto , J. B. Elliott , L. Phair , G. J. Wozniak

Deviations from an idealized equilibrium phase transition picture in nuclear multifragmentation is studied in terms of the entropic index. We investigate different heat-capacity features in the canonical quantum statistical model of nuclear…

Nuclear Theory · Physics 2007-05-23 K. K. Gudima , M. Ploszajczak , V. D. Toneev

Thanks to the high detection quality of the INDRA array, signatures related to the dynamics (spinodal decomposition) and thermodynamics (negative microcanonical heat capacity) of a liquid-gas phase transition have been simultaneously…

Experimental data for central collisions of $^{129}$Xe on $^{119}$Sn at beam energies of (a) 32 MeV/nucleon, (b) 39 MeV/nucleon, (c) 45 MeV/nucleon and (d) 50 MeV/nucleon are compared with results calculated using a hybrid model. We use a…

Nuclear Theory · Physics 2015-05-20 S. Mallik , G. Chaudhuri , S. Das Gupta
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