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Register a new userThe critical temperature of nuclear matter and fragment distributions in multifragmentation of finite nuclei
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The fragment production in multifragmentation of finite nuclei is affected by the critical temperature of nuclear matter. We show that this temperature can be determined on the basis of the statistical multifragmentation model (SMM) by analyzing the evolution of fragment distributions with the excitation energy. This method can reveal a decrease of the critical temperature that, e.g., is expected for neutron-rich matter. The influence of isospin on fragment distributions is also discussed.
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Multifragmentation reactions are dominating processes for the decomposition of highly excited nuclei leading to the fragment production in heavy-ion collisions. At high energy reactions strange particles are abundantly produced. We present a novel development of the Statistical multifragmentation model (SMM) as its generalization for the hyper-matter which is formed after the hyperon capture. In this way, it is possible to describe its disintegration into normal and hyper-nuclei. Some properties of hyper-nuclei and their binding energies can be determined from the comparison of the isotope yields. The main focus of this method is to investigate strange and multi-strange hypernuclei since their properties are not easy to measure in traditional hyper-nuclei experiments.
The incompressibility (compression modulus) $K_{rm 0}$ of infinite symmetric nuclear matter at saturation density has become one of the major constraints on mean-field models of nuclear many-body systems as well as of models of high density matter in astrophysical objects and heavy-ion collisions. We present a comprehensive re-analysis of recent data on GMR energies in even-even $^{rm 112-124}$Sn and $^{rm 106,100-116}$Cd and earlier data on 58 $le$ A $le$ 208 nuclei. The incompressibility of finite nuclei $K_{rm A}$ is expressed as a leptodermous expansion with volume, surface, isospin and Coulomb coefficients $K_{rm vol}$, $K_{rm surf}$, $K_tau$ and $K_{rm coul}$. textit{Assuming} that the volume coefficient $K_{rm vol}$ is identified with $K_{rm 0}$, the $K_{rm coul}$ = -(5.2 $pm$ 0.7) MeV and the contribution from the curvature term K$_{rm curv}$A$^{rm -2/3}$ in the expansion is neglected, compelling evidence is found for $K_{rm 0}$ to be in the range 250 $ < K_{rm 0} < $ 315 MeV, the ratio of the surface and volume coefficients $c = K_{rm surf}/K_{rm vol}$ to be between -2.4 and -1.6 and $K_{rm tau}$ between -840 and -350 MeV. We show that the generally accepted value of $K_{rm 0}$ = (240 $pm$ 20) MeV can be obtained from the fits provided $c sim$ -1, as predicted by the majority of mean-field models. However, the fits are significantly improved if $c$ is allowed to vary, leading to a range of $K_{rm 0}$, extended to higher values. A self-consistent simple (toy) model has been developed, which shows that the density dependence of the surface diffuseness of a vibrating nucleus plays a major role in determination of the ratio K$_{rm surf}/K_{rm vol}$ and yields predictions consistent with our findings.
Heavy mesons in nuclear matter and nuclei are analyzed within different frameworks, paying a special attention to unitarized coupled-channel approaches. Possible experimental signatures of the properties of these mesons in matter are addressed, in particular in connection with the future FAIR facility at GSI.
We systematically investigate the vacuum stability and nuclear properties in the effective chiral model with higher order terms in $sigma$. We evaluate the model parameters by considering the saturation properties of nuclear matter as well as the normal vacuum to be globally stable at zero and finite baryon densities. We can find parameter sets giving moderate equations of state, and apply these models to finite nuclei.
In peripheral collisions of relativistic heavy ions highly excited spectators containing Lambda-hyperons can be produced. Such strange spectator matter may undergo a break-up into many fragments (multifragmentation) as it is well established for ordinary nuclear systems. We generalize the statistical multifragmentation model, previously successfully used for the description of experimental data, for the case of hypernuclear systems. We predict relative yields of hypernuclei and the main characteristics of such a break-up. We point at a connection of this phenomenon with a liquid-gas phase transition in hypermatter.
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