Hy Zhang

Measurement of reaction cross section for proton-rich nuclei ( A< 30) at intermediate energies

Radioactive ion beams were produced through the projectile fragmentation induced by 69 MeV/nucleon Ar-36 primary beam on a Be-9\ target. Measurements of reaction cross sections (sigma(R)s) for 44 nuclei with A < 30 (mostly proton-rich), on carbon were performed on RIBLL (Radioactive Ion Beam Line in Lanzhou) of HIRFL (Heavy Ion Research Facility in Lanzhou) at intermediate energies around 30 MeV/nucleon by a transmission method. The experimental sigma(R) values for Al-23 and P-27 are abnormally large compared with their neighboring nuclei. Together with the previous experimental facts such as the binding energy and ground state data, it suggests anomalously large matter root-mean-square radii and proton halo structure in Al-23 and in P-27. There is an enhancement for the sigma(R) of F-17 + C-12 compared with the neighboring isotopes. Considering that the ground state of F-17 is 1d(5/2), this can indicate that there is a proton skin in F-17. The calculation of relativistic density-dependent Hartree model (RDDH) shows that the nuclei Al-23 and P-27 may have proton-halo structure and F-17 may have proton-skin structure. The significance of these measurements is discussed

Isospin influences on particle emission and critical phenomena in nuclear dissociation

Features of particle emission and critical point behavior are investigated as functions of the isospin of disassembling sources and temperature at a moderate freeze-out density far medium-size Xe isotopes in the framework of the isospin-dependent lattice gas model. Multiplicities of emitted light particles, isotopic, and isobaric ratios of light particles show the strong dependence on the isospin of the dissociation source, but double ratios of light isotope pairs and the critical temperature determined by the extreme values of some critical observables are insensitive to the isospin of the systems. Values of the power law parameter of cluster mass distribution, mean multiplicity of intermediate mass fragments (IMF), information entropy, and Campis second moment also show a minor dependence on the isospin of Xe isotopes at the critical point. In addition, the slopes of the average multiplicities of the neutrons (N-n), protons (N-p), charged particles (N-CP), and IMFs (N-IMF), slopes of the largest fragment mass number (A(max)), and the excitation energy per nucleon of the disassembling source (E*/A) to temperature are investigated as well as variances of the distributions of N-n, N-p, N-CP, N-IMF, A(max), and E*/A. It is found that they can be taken as additional judgements to the critical phenomena. [S0556-2813(99)302108-1].

Theoretical study on the properties of some superheavy nuclei

Abstract The structures of some superheavy nuclei are investigated using self-consistent relativistic mean-field (RMF) model. The calculated binding energies and alpha-decay energies are in good agreement with experimental data. The theoretical lifetime reasonably agrees with the data. The properties of some unknown superheavy nuclei are predicted. A discussion on the deformed shell around Z=108 is made.

Directed and elliptic flows in heavy ion collisions at intermediate energies

A theoretical investigation of directed and elliptic flows for different light particles and fragments in collisions of 40Ca + 40Ca and 112Sn + 112Sn is conducted below 100 MeV/nucleon in the isospin-dependent quantum molecular dynamics model. With increasing incident energy, the directed flow rises from negative to positive, while the elliptic flow decreases with the increasing incident energies. The directed flow for 40Ca + 40Ca system is not sensitive to the nuclear equation of states (EOS), but the directed flow for 112Sn + 112Sn system is sensitive to the EOS. However, the elliptic flows for both 40Ca + 40Ca and 112Sn + 112Sn systems are not sensitive to EOS. A study of the dependence of directed and elliptic flows on fragment charge (mass) is also performed. The information on EOS can be extracted by investigating the directed flow at intermediate energies when the combined mass is large or small.

Investigations on light proton-rich nuclei with exotic structure

Abstract One of the proton halo candidates 23Al and its isotopes are systematically investigated in the nonlinear Relativistic Mean-Field and Skyrme Hartree-Fock approaches. It is shown that there exists the energy inversion of ( 5 2 ) + (202) and ( 1 2 ) + (211) orbitals in 23Al nucleus and which may produce the large enhancement of reaction cross section comparing with its neighboring nuclei. Meanwhile, it is obvious to see that the isospin effect of the pairing correlation plays a great role to the separation energy when the Al isotopes approach to the proton drip line. In addition, the ground state and excited state of 9B, 13N are also investigated in the RMF model. There may exist the halo structure in 13N when the last proton of 13N occupies in the first excited state.

Dynamical spacetimes in conformal gravity

Abstract The conformal gravity remarkably boosts our prehension of gravity theories. We find a series of dynamical solutions in the W 2 -conformal gravity, including generalized Schwarzschild–Friedmann–Robertson–Walker (GSFRW), charged generalized Schwarzschild–Friedmann–Robertson–Walker (CGSFRW), especially rotating Friedmann–Robertson–Walker (RFRW), charged rotating Friedmann–Robertson–Walker (CRFRW), and a dynamical cylindrically symmetric solutions. The RFRW, CRFRW and the dynamical cylindrically symmetric solutions are never found in the Einstein gravity and modified gravities. The GSFRW and CGSFRW solutions take different forms from the corresponding solutions in the Einstein gravity.

Study of incident energy and isospin dependencies of total reaction cross section via the BUU model

The incident energy and isospin dependencies of total reaction cross sections sigma(R) have been researched by using the Boltzmann-Uehling-Uhlenbeck (BUU) model. When the width parameter of square-type or 140-type density distribution is obtained by fitting the sigma(R) at relativistic energies, the calculated result with BUU-model can reproduce the experimental data at intermediate energies better than that with Glauber-model of optical limit approximation. The systematical underestimation of sigma(R) at intermediate energy was removed out by BUU calculation framework. It is found that sigma(R) is sensitive to nuclear equation of state (EOS). It is also found that the difference factor (d) defined in text is sensitive to the nuclear structure such as neutron halo and neutron skin, etc

Higgs inflation on braneworld

We discuss a Higgs inflation model in the warped DGP braneworld background. It generates reasonable primordial perturbations. At the same time, with enhanced nonminimal coupling, it overcomes the severe problem in the Higgs inflation in four dimensions, which. says that the effective field theory becomes invalid at an energy scale far below the energy scale for inflation exit. Furthermore, we present the constraints for the parameters confronted to PLANCK and related observations. PLANCK low-l data almost fixes the inflation energy scale in this Higgs inflation model with specific brane parameters.

Possible exotic structure in light proton-rich nuclei

Radioactive ion beams were produced through the projectile fragmentation induced by 69MeV/nucleon 36Ar primary beam on a 9Be target. Measurements of reaction cross section (σR) for some proton-rich nuclei on carbon target at intermediate energies around 30MeV/nucleon have been performed on RIBLL of HIRFL by transmission method and transmission plus transportation method. The experimental σR values for 23Al and 27P are abnormally large compared with their neighboring nuclei and that of 17F has an enhancement compared with the neighboring isotopes. It suggests anomalously large matter root-mean-square radii and proton halo structure in 23Al and 27P. The experimental σR values and momentum distribution of fragmentation reaction product for 31Cl, 32Cl, 33Cl, 28S, 29S were performed also on RIBLL by transmission and transportation method. These data are in analyzing. The calculation of relativistic density-dependent Hartree shows that the nuclei 23Al, 27P, 31Cl may have proton-halo structure and 17F, 32Cl may ...

Proton halos in exotic light nuclei

The current study on proton halos in exotic light nuclei is reviewed and discussed. We place emphasis on the newly discovered proton halo in 23Al. A measurement of the reaction cross section of N=10 isotones and Z=13 isotopes is performed at Lanzhou in China. An abnormal increase in the reaction cross section is observed for 23Al. This abnormal increase, combined with other data, strongly suggests that there is a proton halo in 23Al. The possible cause for a proton halo in 23Al is analyzed, and it is found that deformation can be important for it. Other candidates for proton halos are predicted.