Critical phenomena in nuclear fragmentation

Bonasera, A.; Bruno, M.; Dorso, C. O.; Mastinu, P.

doi:10.1007/bf03548882

Cited by 98 publications

(127 citation statements)

References 125 publications

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“…The results obtained from the analysis of the gamma-ray spectra in different mass regions provided evidence for a mass dependence of the limiting excitation energy (or temperature) for the existence of the GDR. The disappearance of the collective motion has been interpreted by some theoreticians as one of the possible signatures for a phase transitions in nuclei [106,107]. From this point of view, probing the limits of the collective motion in nuclei represents complementary approach to extract information on the liquid-gas phase transition which has been investigated using different experimental probes and theoretical approaches.…”

Section: Mass Dependence Of the Gdr Quenchingmentioning

confidence: 99%

The hot GDR revisited

Santonocito

Blumenfeld

2020

Eur. Phys. J. A

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The properties of the Isovector Giant Dipole Resonance are reviewed as a function of the temperature of the state on which it is built. The experimental methods, based on scintillation detectors efficient for the detection of high energy gamma-rays, are described. Methods for determining the excitation energy and temperature from the measurement of light charged particle energy spectra taking pre-equilibrium emission into account are presented. The resonance properties, energy, width and strength, are followed as a function of increasing temperature. The data are analyzed in the framework of the statistical model, which is briefly presented, by using the codes CASCADE and DCASCADE. Various prescriptions for the characteristics of the resonance as well as theoretical models are incorporated into these statistical codes in view of a direct comparison with the data. The successes and deficiencies of the Thermal Shape Fluctuation model at low temperatures are discussed. A salient feature is the surprisingly abrupt disappearance of dipole strength above a limiting temperature which depends on the nuclear mass. Several models taking into account the competition between the time scales of collective degrees of freedom and nuclear lifetime only roughly reproduce the trend of the data. This disappearance of strength is tentatively linked to the nuclear liquid–gas phase transition.

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Section: Mass Dependence Of the Gdr Quenchingmentioning

confidence: 99%

The hot GDR revisited

Santonocito

Blumenfeld

2020

Eur. Phys. J. A

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“…In this paper, the reactions of 40 Ca+ 40 Ca at incident energies E int /A = 40MeV-120MeV were simulated by IQMD model which takes into account the in-medium NNCS in the process of two-body collisions. A soft nuclear equation of state is used in the present simulation.…”

Section: Resultsmentioning

confidence: 99%

“…As an example, Fig. 1(a) shows the time evolution of average density ρ and differential hard photon production probability in the reaction of 40 Ca+ 40 Ca@60 MeV/nucleon at an impact parameter b = 0.0 fm, respectively. It is found that the hard photon production probability is sensitive to the density during the whole evolution process.…”

Section: Definitions Of Directs Photon and Thermal Photonsmentioning

confidence: 99%

“…direct photon and thermal photon sources) in space and time according to the experimental evidence as well as the Boltzmann-Uehling-Uhlenbeck (BUU) model calculations [36,37]. Although there are some hot fragments formed in heavy-ion collisions which could result in a larger width of giant dipole resonance (GDR) energy spectrum and the energy of GDR photons might be higher than 30MeV [40], the GDR strength is much weaker than the bremsstrahlung photon cross section. So generally, the photons with energy above 30MeV is dominated by hard photons [41].…”

Section: Introductionmentioning

confidence: 99%

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Azimuthal anisotropy and multiplicities of hard photons and free nucleons in intermediate-energy heavy-ion collisions

Wang,

Ma,

Cao

et al. 2020

Preprint

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Anisotropic flow can offer significant information of evolution dynamics in heavy-ion collisions. A systematic study of the directed flow v1 and elliptic flow v2 of hard photons and free nucleons is performed for 40 Ca+ 40 Ca collisions in a framework of isospin dependent quantum molecular dynamics (IQMD) model. The study firstly reveals that thermal photons emitted in intermediate-energy heavy-ion collisions have the behaviors of directed and elliptic flows. The interesting phenomena of incident energy dependence of v1 and v2 for thermal photons in central collisions also confirmed that it can be regarded as a good probe of evolution dynamics. Moreover, the multiplicities of hard photons and free nucleons and their correlation are also investigated. We find that direct photon emission is positively related to free nucleons emission, however, there exists an anti-correlation for thermal photons with free nucleons.

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“…Starting in the 1980's, a lot of attention has been paid to the identification and characterization of the occurrence of a nuclear liquid-gas phase transition. On one hand, indications of critical behavior were obtained assuming a Fisher-like scaling relation for fragment mass distributions [1,2,3,4]. On the other, it has been claimed that the observed critical behavior in static observables is compatible with a first order phase transition [5,6,7,8,9].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of kinetic energy fluctuations due to expansion

et al. 2004

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Global equilibrium fragmentation inside a freeze out constraining volume is a working hypothesis widely used in nuclear fragmentation statistical models. In the framework of classical Lennard Jones molecular dynamics, we study how the relaxation of the fixed volume constraint affects the posterior evolution of microscopic correlations, and how a non-confined fragmentation scenario is established. A study of the dynamical evolution of the relative kinetic energy fluctuations was also performed. We found that asymptotic measurements of such observable can be related to the number of decaying channels available to the system at fragmentation time.Comment: 6 pages, 4 figure

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Critical phenomena in nuclear fragmentation

Cited by 98 publications

References 125 publications

The hot GDR revisited

The hot GDR revisited

Azimuthal anisotropy and multiplicities of hard photons and free nucleons in intermediate-energy heavy-ion collisions

Enhancement of kinetic energy fluctuations due to expansion

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