Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userDifferential analysis of incompressibility in neutron-rich nuclei
119
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Both the incompressibility Ka of a finite nucleus of mass A and that ($K_{infty}$) of infinite nuclear matter are fundamentally important for many critical issues in nuclear physics and astrophysics. While some consensus has been reached about the $K_{infty}$, accurate theoretical predictions and experimental extractions of $K_{tau}$ characterizing the isospin dependence of Ka have been very difficult. We propose a differential approach to extract the Kt and Ki independently from the Ka data of any two nuclei in a given isotope chain. Applying this new method to the Ka data from isoscalar giant monopole resonances (ISGMR) in even-even Pb, Sn, Cd and Ca isotopes taken by U. Garg {it et al.} at the Research Center for Nuclear Physics (RCNP), Osaka University, Japan, we find that the $^{106}$Cd-$^{116}$Cd and $^{112}$Sn-$^{124}$Sn pairs having the largest differences in isospin asymmetries in their respective isotope chains measured so far provide consistently the most accurate up-to-date Kt value of $K_{tau}=-616pm 59$ MeV and $K_{tau}=-623pm 86$ MeV, respectively, largely independent of the remaining uncertainties of the surface and Coulomb terms in expanding the $K_{rm A}$, while the $K_{infty}$ values extracted from different isotopes chains are all well within the current uncertainty range of the community consensus for $K_{infty}$. Moreover, the size and origin of the Soft Sn Puzzle is studied with respect to the Stiff Pb Phenomenon. It is found that the latter is favored due to a much larger (by $sim 380$ MeV) Kt for Pb isotopes than for Sn isotopes, while the Ki from analyzing the Ka data of Sn isotopes is only about 5 MeV less than that from analyzing the Pb data.
rate research
Read More
We calculate the ground, first intrinsic excited states and density distribution for neutron-rich thorium and uranium isotopes, within the framework of relativistic mean field(RMF) approach using axially deformed basis. The total nucleon densities are calculated, from which the cluster-structures inside the parent nuclei are determined. The possible modes of decay, like {alpha}-decay and b{eta} -decay are analyzed. We find the neutron-rich isotopes are stable against {alpha}-decay, however they are very much unstable against b{eta} -decay. The life time of these nuclei predicted to be tens of second against b{eta} -decay.
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.
The symmetry energy obtained with the effective Skyrme energy density functional is related to the values of isoscalar effective mass and isovector effective mass, which is also indirectly related to the incompressibility of symmetric nuclear matter. In this work, we analyze the values of symmetry energy and its related nuclear matter parameters in five-dimensional parameter space by describing the heavy ion collision data, such as isospin diffusion data at 35 MeV/u and 50 MeV/u, neutron skin of $^{208}$Pb, and tidal deformability and maximum mass of neutron star. We obtain the parameter sets which can describe the isospin diffusion, neutron skin, tidal deformability and maximum mass of neutron star, and give the incompressibility $K_0$=250.23$pm$20.16 MeV, symmetry energy coefficient $S_0$=31.35$pm$2.08 MeV, the slope of symmetry energy $L$=59.57$pm$10.06 MeV, isoscalar effective mass $m_s^*/m$=0.75$pm$0.05 and quantity related to effective mass splitting $f_I$=0.005$pm$0.170. At two times normal density, the symmetry energy we obtained is in 35-55 MeV. To reduce the large uncertainties of $f_I$, more critical works in heavy ion collisions at different beam energies are needed.
In this work we investigate the possible condensation of tetraneutron resonant states in the lower density neutron rich gas regions inside Neutron Stars (NSs). Using a relativistic density functional approach we characterize the system containing different hadronic species including, besides tetraneutrons, nucleons and a set of light clusters ($^3$He, $alpha$ particles, deuterium and tritium). $sigma,omega$ and $rho$ mesonic fields provide the interaction in the nuclear system. We study how the tetraneutron presence could significantly impact the nucleon pairing fractions and the distribution of baryonic charge among species. For this we assume that they can be thermodynamically produced in an equilibrated medium and scan a range of coupling strengths to the mesonic fields from prescriptions based on isospin symmetry arguments. We find that tetraneutrons may appear over a range of densities belonging to the outer NS crust carrying a sizable amount of baryonic charge thus depleting the nucleon pairing fractions.
We discuss the present status of the description of the structure of the very neutron rich nuclei, in the framework of modern large scale shell model calculations. Particular attention is paid to the interaction related issues, as well as to the problems of the shell model approach at the neutron drip line. We present detailed results for nuclei around N=20 and, more briefly, we discuss some salient features of the regions close to N=8, 28 and 40. We show that most experimental features can be understood in a shell model context.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
