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Register a new userRevised analysis of $^{40}$Ca+$^{96}$Zr fusion reactions
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Fusion data for $^{40}$Ca+$^{96}$Zr are analyzed by coupled-channels calculations that are based on a standard Woods-Saxon potential and include couplings to multiphonon excitations and transfer channels. The couplings to multiphonon excitations are the same as used in a previous work. The transfer couplings are calibrated to reproduce the measured neutron transfer data. This type of calculation gives a poor fit to the fusion data. However, by multiplying the transfer couplings with a $sqrt{2}$ one obtains an excellent fit. The scaling of the transfer strengths is supposed to simulate the combined effect of neutron and proton transfer, and the calculated one- and two-nucleon transfer cross sections are indeed in reasonable agreement with the measured cross sections.
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The production of $rm{^3_Lambda H}$ and $rm{{^3_{overline Lambda}overline H}}$, as well as $rm{^3H}$, $rm{{^3overline H}}$, $rm{^3He}$, and $rm{{^3overline {He}}}$ are studied in central collisions of isobars $^{96}_{44}$Ru+$^{96}_{44}$Ru and $^{96}_{40}$Zr+$^{96}_{40}$Zr at $sqrt{s_{rm{NN}}}=200$ GeV, using the dynamically constrained phase-space coalescence model and the {footnotesize PACIAE} model with chiral magnetic effect. The yield, yield ratio, coalescence parameters, and strangeness population factor of (anti-)hypertriton and (anti-)nuclei produced in isobaric $^{96}_{44}$Ru+$^{96}_{44}$Ru and $^{96}_{40}$Zr+$^{96}_{40}$Zr collisions are predicted. The (anti-)hypertriton and (anti-)nuclei production is found to be insensitive to the chiral magnetic effects. Experimental data of Cu+Cu, Au+Au and Pb+Pb collisions from RHIC, LHC, and the results of {footnotesize PACIAE+DCPC} model are presented in the results for comparison.
In the hydrodynamic model description of heavy ion collisions, the elliptic flow $v_2$ and triangular flow $v_3$ are sensitive to the quadrupole deformation $beta_2$ and octupole deformation $beta_3$ of the colliding nuclei. The relations between $v_n$ and $beta_n$ have recently been clarified and were found to follow a simple parametric form. The STAR Collaboration have just published precision $v_n$ data from isobaric $^{96}$Ru+$^{96}$Ru and $^{96}$Zr+$^{96}$Zr collisions, where they observe large differences in central collisions $v_{2,mathrm{Ru}}>v_{2,mathrm{Zr}}$ and $v_{3,mathrm{Ru}}<v_{3,mathrm{Zr}}$. Using a transport model simulation, we show that these orderings are a natural consequence of $beta_{2,mathrm{Ru}}ggbeta_{2,mathrm{Zr}}$ and $beta_{3,mathrm{Ru}}llbeta_{3,mathrm{Zr}}$. We are able to reproduce the centrality dependence of the $v_2$ ratio qualitatively and $v_3$ ratio quantitatively, and extract values of $beta_2$ and $beta_3$ that are consistent with those measured at low energy nuclear structure experiments. STAR data provide the first direct evidence of strong octupole correlations in the ground state of $^{96}$Zr in heavy ion collisions. Our analysis demonstrates that flow measurements in high-energy heavy ion collisions, especially using isobaric systems, are a new precision tool to study nuclear structure physics.
Anomalous Viscous Fluid Dynamics (AVFD) model calculations for $mathrm{^{96}_{44}Ru +, ^{96}_{44}Ru}$ and $mathrm{^{96}_{40}Zr +, ^{96}_{40}Zr}$ collisions ($sqrt{s_{rm NN}} = 200$ GeV) are used in concert with a charge-sensitive correlator, to test its ability to detect and characterize the charge separation difference expected from the Chiral Magnetic Effect (CME) in these isobaric collisions. The tests indicate a larger charge separation for $mathrm{^{96}_{44}Ru +, ^{96}_{44}Ru}$ than for $mathrm{^{96}_{40}Zr +, ^{96}_{40}Zr}$ collisions, and a discernible CME-driven difference of $sim 10$% in the presence of realistic non-CME backgrounds. They also indicate a strategy for evaluating the relative influence of the background correlations, present for each isobar. These results suggest that charge separation measurements for these isobaric species could serve to further constrain unambiguous identification and characterization of the CME in upcoming measurements at RHIC.
We study pre-equilibrium giant dipole resonance excitation and fusion in the neutron-rich system $^{132}$Sn+$^{48}$Ca at energies near the Coulomb barrier, and we compare photon yields and total fusion cross sections to those of the stable system $^{124}$Sn+$^{40}$Ca. The dynamic microscopic calculations are carried out on a three-dimensional lattice using both the Time-Dependent Hartree-Fock method and the Density Constrained TDHF method. We demonstrate that the peak of the GDR excitation spectrum occurs at a substantially lower energy than expected for an equilibrated system, thus reflecting the very large prolate elongation of the dinuclear complex during the early stages of fusion. Our theoretical fusion cross-sections for both systems agree reasonably well with recent data measured at HRIBF.
An approach to the Generator Coordinate Method (GCM) using Skyrme-type effective forces and Woods-Saxon construction potential is applied to calculate the single-particle proton and neutron overlap functions in $^{40}$Ca. The relationship between the bound-state overlap functions and the one-body density matrix has been used. These overlap functions are applied to calculate the cross sections of one-nucleon removal reactions such as ($e,ep$), ($gamma,p$) and ($p,d$) on $^{40}$Ca on the same theoretical footing. A consistent description of data for the different reactions is achieved. The shapes of the experimental cross sections for transitions to the $3/2^{+}$ ground state and the first $1/2^{+}$ excited state of the residual nuclei are well reproduced by the overlap functions obtained within the GCM. An additional spectroscopic factor accounting for correlations not included in the overlap function must be applied to the calculated results to reproduce the size of the experimental cross sections.
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