dorsal/arxiv
View SchemaGeneralized entropy and temperature in nuclear multifragmentation
| Authors | A. Atalmi, M. Baldo, G. F. Burgio, A. Rapisarda |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/9806053 |
| URL | https://arxiv.org/abs/nucl-th/9806053 |
| DOI | 10.1103/PhysRevC.58.2238 |
| Journal | Phys.Rev. C58 (1998) 2238-2248 |
Abstract
In the framework of a 2D Vlasov model, we study the time evolution of the "coarse-grained" Generalized Entropy (GE) in a nuclear system which undergoes a multifragmentation (MF) phase transition. We investigate the GE both for the gas and the fragments (surface and bulk part respectively). We find that the formation of the surface causes the growth of the GE during the process of fragmentation. This quantity then characterizes the MF and confirms the crucial role of deterministic chaos in filling the new available phase-space: at variance with the exact time evolution, no entropy change is found when the linear response is applied. Numerical simulations were used also to extract information about final temperatures of the fragments. From a fitting of the momentum distribution with a Fermi-Dirac function we extract the temperature of the fragments at the end of the process. We calculate also the gas temperature by averaging over the available phase space. The latter is a few times larger than the former, indicating a gas not in equilibrium. Though the model is very schematic, this fact seems to be very general and could explain the discrepancy found in experimental data when using the slope of light particles spectra instead of the double ratio of isotope yields method in order to extract the nuclear caloric curve.
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"abstract": "In the framework of a 2D Vlasov model, we study the time evolution of the\n\"coarse-grained\" Generalized Entropy (GE) in a nuclear system which undergoes a\nmultifragmentation (MF) phase transition. We investigate the GE both for the\ngas and the fragments (surface and bulk part respectively). We find that the\nformation of the surface causes the growth of the GE during the process of\nfragmentation. This quantity then characterizes the MF and confirms the crucial\nrole of deterministic chaos in filling the new available phase-space: at\nvariance with the exact time evolution, no entropy change is found when the\nlinear response is applied. Numerical simulations were used also to extract\ninformation about final temperatures of the fragments. From a fitting of the\nmomentum distribution with a Fermi-Dirac function we extract the temperature of\nthe fragments at the end of the process. We calculate also the gas temperature\nby averaging over the available phase space. The latter is a few times larger\nthan the former, indicating a gas not in equilibrium. Though the model is very\nschematic, this fact seems to be very general and could explain the discrepancy\nfound in experimental data when using the slope of light particles spectra\ninstead of the double ratio of isotope yields method in order to extract the\nnuclear caloric curve.",
"arxiv_id": "nucl-th/9806053",
"authors": [
"A. Atalmi",
"M. Baldo",
"G. F. Burgio",
"A. Rapisarda"
],
"categories": [
"nucl-th",
"chao-dyn",
"cond-mat.stat-mech",
"nlin.CD",
"nucl-ex"
],
"doi": "10.1103/PhysRevC.58.2238",
"journal_ref": "Phys.Rev. C58 (1998) 2238-2248",
"title": "Generalized entropy and temperature in nuclear multifragmentation",
"url": "https://arxiv.org/abs/nucl-th/9806053"
},
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