Hot fragmentation of nuclei

Trautmann, W.

doi:10.1016/s0375-9474(01)00543-7

Cited by 9 publications

(7 citation statements)

References 50 publications

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“…[12,13]). It was confirmed by experimental results [26], and by rather sophisticated calculations of Fermionic Molecular Dynamics [27] and Antisymmetrized Molecular Dynamics [28]. The reason for large fluctuations of the temperature and A max , can be clear from Figs.…”

Section: Temperature and Bimodalitysupporting

confidence: 64%

Isospin and symmetry energy effects on nuclear fragment production in liquid-gas-type phase transition region

2005

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We have demonstrated that the isospin of nuclei influences the fragment production during the nuclear liquid-gas phase transition. Calculations for Au 197 , Sn 124 , La 124 and Kr 78 at various excitation energies were carried out on the basis of the statistical multifragmentation model (SMM). We analyzed the behavior of the critical exponent τ with the excitation energy and its dependence on the critical temperature. Relative yields of fragments were classified with respect to the mass number of the fragments in the transition region. In this way, we have demonstrated that nuclear multifragmentation exhibits a 'bimodality' behavior. We have also shown that the symmetry energy has a small influence on fragment mass distribution, however, its effect is more pronounced in the isotope distributions of produced fragments. PACS. 25.70.Pq Multifragment emission and correlations -21.65.+f Nuclear matter -24.60.-k Statistical theory and fluctuations

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Section: Temperature and Bimodalitysupporting

confidence: 64%

Isospin and symmetry energy effects on nuclear fragment production in liquid-gas-type phase transition region

2005

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“…One may see from this figure that at an excitation energy of E* = 4 MeV/n (corresponding temperature T ≤ 5 MeV), there is a U-shape distribution corresponding to partitions with few small fragments and one big residual fragment. In the so called transition region (T ≈ 5 − 6 MeV), however, variation of T with E* exhibits a plateau-like behavior that can be interpreted as a sign of liquid-gas phase transition in the system [11,12,13], and one observes a smooth transformation for E* = 5 MeV/n in the same figure. At high temperatures (T ≥ 6 MeV) for E* = 8 MeV/n, the big fragments disappear and an exponential-like fall-off is observed.…”

Section: Calculations and Resultsmentioning

confidence: 98%

Mass distributions for nuclear disintegration from fission to evaporation

Eren¹,

Buyukcizmeci²,

Ogul³

2007

Phys. Scr.

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By a proper choice of the excitation energy per nucleon we analyze the mass distributions of the nuclear fragmentation at various excitation energies. Starting from low energies (between 0.1 and 1 MeV/nucleon) up to higher energies about 12 MeV/n, we classified the mass yield characteristics for heavy nuclei (A > 200) on the basis of Statistical Multifragmentation Model. The evaluation of fragment distribution with the excitation energy show that the present results exhibit the same trend as the experimental ones.

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“…The study of nuclear properties at nonzero temperatures has been investigated since the pioneering works [1][2][3][4] describing the formation and decay of a compound nucleus induced by light projectiles in nuclear reactions. In the last years nuclear reactions involving high-energy projectiles and heavy ions producing a variety of excited nuclei have been investigated [1,[5][6][7][8]. Construction of the caloric curve furnishes one * ronai@ect.ufrn.br possible way of comparing nuclear temperatures and excitation energies [7].…”

Section: Introductionmentioning

confidence: 99%

Dirac-Hartree-Bogoliubov calculation for spherical and deformed hot nuclei: Temperature dependence of the pairing energy and gaps, nuclear deformation, nuclear radii, excitation energy, and entropy

2016

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Background: Unbound single-particle states become important in determining the properties of a hot nucleus as its temperature increases. We present relativistic mean field (RMF) for hot nuclei considering not only the self-consistent temperature and density dependence of the self-consistent relativistic mean fields but also the vapor phase that takes into account the unbound nucleon states. Purpose: The temperature dependence of the pairing gaps, nuclear deformation, radii, binding energies, entropy, and caloric curves of spherical and deformed nuclei are obtained in self-consistent RMF calculations up to the limit of existence of the nucleus. Method: We perform Dirac-Hartree-Bogoliubov (DHB) calculations for hot nuclei using a zero-range approximation to the relativistic pairing interaction to calculate proton-proton and neutron-neutron pairing energies and gaps. A vapor subtraction procedure is used to account for unbound states and to remove long range Coulomb repulsion between the hot nucleus and the gas as well as the contribution of the external nucleon gas. Results: We show that p-p and n-n pairing gaps in the 1 S 0 channel vanish for low critical temperatures in the range T c p ≈ 0.6-1.1 MeV for spherical nuclei such as 90 Zr, 124 Sn, and 140 Ce and for both deformed nuclei 150 Sm and 168 Er. We found that superconducting phase transition occurs at T c p = 1.03 pp (0) for 90 Zr, T c p = 1.16 pp (0) for 140 Ce, T c p = 0.92 pp (0) for 150 Sm, and T c p = 0.97 pp (0) for 168 Er. The superfluidity phase transition occurs at T c p = 0.72 nn (0) for 124 Sn, T c p = 1.22 nn (0) for 150 Sm, and T c p = 1.13 nn (0) for 168 Er. Thus, the nuclear superfluidity phase-at least for this channel-can only survive at very low nuclear temperatures and this phase transition (when the neutron gap vanishes) always occurs before the superconducting one, where the proton gap is zero. For deformed nuclei the nuclear deformation disappear at temperatures of about T c s = 2.0-4.0 MeV, well above the critical temperatures for pairing, T c p . If we associate the melting of hot nuclei into the surrounding vapor with the liquid-gas phase transition our results indicate that it occurs at temperatures around T = 8.0-10.0 MeV, somewhat higher than observed in many experimental results. Conclusions: The change of the pairing fields with the temperature is important and must be taken into account in order to define the superfluidity and superconducting phase transitions. We obtain a Hamiltonian form of the pairing field calibrated by an overall constant c pair to compensate for deficiencies of the interaction parameters and of the numerical calculation. When the pairing is not zero, the states close to the Fermi energy make the principal contribution to the anomalous density that appears in the pairing field. By including temperature through the use of the Matsubara formalism, the normal and anomalous densities are multiplied by a Fermi occupation factor. This leads to a reduction in the anomalous density and in the pairing as the temper...

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Hot fragmentation of nuclei

Cited by 9 publications

References 50 publications

Isospin and symmetry energy effects on nuclear fragment production in liquid-gas-type phase transition region

Isospin and symmetry energy effects on nuclear fragment production in liquid-gas-type phase transition region

Mass distributions for nuclear disintegration from fission to evaporation

Dirac-Hartree-Bogoliubov calculation for spherical and deformed hot nuclei: Temperature dependence of the pairing energy and gaps, nuclear deformation, nuclear radii, excitation energy, and entropy

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