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Understanding gluon density distributions and how they are modified in nuclei are among the most important goals in nuclear physics. In recent years, diffractive vector meson production measured in ultra-peripheral collisions (UPCs) at heavy-ion colliders has provided a new tool for probing the gluon density. In this Letter, we report the first measurement of $J/\psi$ photoproduction off the deuteron in UPCs at the center-of-mass energy $\sqrt{s_{_{\rm NN}}}=200~\rm GeV$ in d$+$Au collisions. The differential cross section as a function of momentum transfer $-t$ is measured. In addition, data with a neutron tagged in the deuteron-going Zero-Degree Calorimeter is investigated for the first time, which is found to be consistent with the expectation of incoherent diffractive scattering at low momentum transfer. Theoretical predictions based on the Color Glass Condensate saturation model and the gluon shadowing model are compared with the data quantitatively. A better agreement with the saturation model has been observed. With the current measurement, the results are found to be directly sensitive to the gluon density distribution of the deuteron and the deuteron breakup, which provides insights into the nuclear gluonic structure., Comment: Final published version Phys. Rev. Lett. 128, 122303

The isotope Xe-135 has a large thermal neutron absorption cross section and is considered to be the most important fission product. A very small amount of such neutron poison may significantly affect the reactor reactivity since they will absorb the neutrons from chain reaction, therefore monitoring their atomic density variation during reactor operation is extremely important. In a molten reactor system, Xe-135 is entrained in the liquid fuel and continuously circulates through the core where the neutron irradiation functions and the external core where only nuclei decay occurs, at the same time, an off-gas removal system operates for online removing Xe-135 through helium bubbling. These unique features of MSR complicate the Xe-135 dynamic behaviors, and the calculation method applied in the solid fuel reactor system is not suitable. From this point, we firstly analytically deduce the nuclei evolution law of Xe-135 in the flowing salt with an off-gas removal system functioning. A study of Xe-135 dynamic behavior with the core power change, shutdown, helium bubbling failure and startup then is conducted, and several valuable conclusions are obtained for MSR design.

MSR (Molten salt reactor) is a reactor with the fission material dissolved in the fluoride salt as the fuel, which continuously circulates through the primary loop. The liquid fuel makes the online refueling and reprocessing be possible, consequently, more fuel cycle options would be presented due to the introduction of various refueling fuel type and reprocessing mode (continuous / batch reprocessing) comparing with that of the solid fuel reactor systems. It is important to evaluate all the possible fuel cycle options and screen out the promising ones to narrow the R&D activities of TMSR (Thorium-based Molten-Salt Reactor nuclear energy system) program. In this study, we firstly established a screening and decision-making framework, then conducted an initial evaluation work and identified the potential promising fuel cycle options. Synthesizing the goal of TMSR program and technology readiness, we proposed a “Three-steps” fuel cycle development strategy with the aim for gradually increasing the thorium resource utilization while considering the challenges of the reprocessing technology.

High-energy heavy-ion collisions produce abundant hyperons and nucleons. A dynamical coalescence model coupled with the ART model is employed to study the production probabilities of light clusters, deuteron (d), triton (t), helion ((3)He), and hypertriton ((3)(A)H) at subthreshold energy of A production (approximate to 1 GeV per nucleon). We study the dependence on the reaction system size of the coalescence penalty factor per additional nucleon and entropy per nucleon. The Strangeness Population Factor (S(3) =(3)(A)H/((3)He x A/p)) shows an extra suppression of hypertriton comparing to light clusters of the same mass number. This model predicts a hypertriton production cross-section of a few mu b in (36)Ar+(36)Ar, (40)Ca+(40)Ca and (56)Ni+(56)Ni in 1 A GeV reactions. The production rate is as high as a few hypertritons per million collisions, which shows that the fixed-target heavy-ion collisions at CSR (Lanzhou/China) at A subthreshold energy are suitable for breaking new ground in hypernuclear physics.

The correlation between neutron-to-proton yield ratio (R(np)) and neutron skin thickness (delta(np)) in neutron-rich projectile induced reactions is investigated within the framework of the Isospin-Dependent Quantum Molecular Dynamics (IQMD) model. The density distribution of the Droplet model is embedded in the initialization of the neutron and proton densities in the present IQMD model. By adjusting the diffuseness parameter of neutron density in the Droplet model for the projectile, the relationship between the neutron skin thickness and the corresponding R(np) is obtained. The results show strong linear correlation between R(np) and delta(np) for neutron-rich Ca and Ni isotopes. It is suggested that R(np) may be used as an experimental observable to extract delta(np) for neutron-rich nuclei, which is very interesting in the study of the nuclear structure of exotic nuclei, the equation of state (EOS) of asymmetric nuclear matter and neutron-rich matter in astrophysics, etc.

Production and properties of -meson under the extreme hot dense matter which is formed in Au + Au collisions at RHIC energy have been briefly reviewed. The issues are focused on transverse momentum (pT) spectra of , elliptic flow of , nuclear modification factor of , the ratio of ?(pT)/(pT) versus pT, the ratio of ?(pT/3)/(pT/2) versus pT/nq, spin alignment of and the enhancement of etc. These observables give the significant information of the strange quark dynamics in hot dense matter under the extreme condition.

The astrophysical reaction rate of 12C(?, ?)16O plays a key role in massive star evolution. However, this reaction rate and its uncertainties have not been well determined yet, especially at T9 = 0.2. The existing results even disagree with each other to a certain extent. In this paper, the E1, E2 and total (E1+E2) 12C(?, ?)16O reaction rates are calculated in the temperature range from T9 = 0.3 to 2 according to all the available cross section data. A new analytic expression of the 12C(?, ?)16O reaction rate is brought forward based on the reaction mechanism. In this expression, each part embodies the underlying physics of the reaction. Unlike previous works, some physical parameters are chosen from experimental results directly, instead of all the parameters obtained from fitting. These parameters in the new expression, with their 3? fit errors, are obtained from fit to our calculated reaction rate from T9 = 0.3 to 2. Using the fit results, the analytic expression of 12C(?, ?)16O reaction rate is extrapolated down to T9 = 0.05 based on the underlying physics. The 12C(?, ?)16O reaction rate at T9 = 0.2 is (8.78 ? 1.52) ? 1015 cm's?1 mol?1. Some comparisons and discussions about our new 12C(?, ?)16O reaction rate are presented, and the contributions of the reaction rate correspond to the different part of reaction mechanism are given. The agreements of the reaction rate below T9 = 2 between our results and previous works indicate that our results are reliable, and they could be included in the astrophysical reaction rate network. Furthermore, we believe our method to investigate the 12C(?, ?)16O reaction rate is reasonable, and this method can also be employed to study the reaction rate of other astrophysical reactions. Finally, a new constraint of the supernovae production factor of some isotopes are illustrated according to our 12C(?, ?)16O reaction rates.

Assuming a core plus valence nucleon structure, one-nucleon removal reaction is investigated within the framework of few-body Glauber theory. Fermi-type distribution is used for the core density, while the wavefunction of the valence nucleon is calculated by solving the single particle eigenvalue problem of the Schrodinger equation with the Woods-Saxon potential. The parallel momentum distribution (P(parallel to)) of the fragments is calculated for isotopes with 3 < Z < 18. A remarkable scaling property is observed from the dependence of the dimensionless quantity R(v)(2)/R(c)(2) on the full width at half maximum of the parallel momentum distribution (FWHM(P parallel to)). R(v)(2)/R(c)(2) is a measure of the exotic extent of the nuclear halo. Based on the obtained scaling law, FWHM(P parallel to) can be used as an experimental observable to extract R(v)(2)/R(c)(2) and measure the exotic extent for the nuclear halo.

The isoscaling behavior in the reaction system (58,64)Ni + (9)Be has been studied by using the heavy-ion phase-space exploration(HIPSE) model. The extracted isoscaling parameters alpha and beta for both heavy and light fragments for HIPSE model calculations are in good agreement with recent experimental data. The investigation shows that the parameters in the HIPSe model have some effect on the isoscaling parameter. The isoscaling parameters for hot and cold fragments have been extracted.

The temperature dependent width of the fission fragment distributions was simulated in the Langevin equation by taking two-parameter exponential form of the fission fragment mass variance at scission point for each fission event. The result can reproduce experimental data well, and it permits to make reliable estimate for unmeasured product yields near symmetry fission.

Based on the facility of the Shanghai Laser Electron Gamma Source (SLEGS), the transmutation for nuclear wastes such as Cs-137 and I-129 is investigated. It is found that nuclear waste can be transmuted efficiently via photonuclear reaction triggered by gamma photons generated from Compton backscattering between CO2 laser photons and 3.5 GeV electrons. The nuclear activities of Cs-137 and I-129 are evaluated and compared with the results of transmutation triggered by bremsstrahlung gamma photons driven by ultra intense laser. Due to the better character of gamma photon spectrum as well as the high brightness of gamma photons, the transmutation rate of Compton backscattering method is much higher than that of the bremsstrahlung method.

The dependence between neutron skin thickness and neutron abrasion cross section (sigma(nabr)) for neutron-rich nuclei is investigated within the framework of the statistical abrasion ablation model. Assuming that the density distributions for proton and neutron are of Fermi-type, and adjusting the diffuseness parameter of neutron density distribution in the droplet model, we find out the good linear correlation between the neutron skin thickness and the abrasion cross section sigma(nabr) for neutron-rich nuclei. The uncertainty of neutron skin thickness determined from sigma(nabr) is very small. It is suggested that sigma(nabr) can be used as a new experimental observable to extract the neutron skin thickness for neutron-rich nucleus. The scaling behaviours between neutron skin thickness and sigma(nabr), separately, for isotopes of Na26-35, Ar44-56, Ca48-60, Ni67-78 are also investigated.

We investigate the applicability of the independent atom model JAM) to elastic electron scattering from complex polyatomic molecules, namely C4H10 and C6H6, in the energy range 100-1000eV. The cross sections of the elastic electron scattering are calculated by employing the JAM together with the relativistic partial waves. The incorporation of both the modified absorption potential and the extended structural factor in the JAM makes the elastic differential cross sections and momentum transfer cross sections have a good agreement with the available experimental data. The present simple model seems to be insensitive to the complexity of the target molecules so that the proposed procedure can be quite useful for calculation of electron scattering from bio-molecules.

We investigate the differential cross sections (DCS) of elastic electron scattering from CH4, CF4 and SF6 at six impact energies in a range of 100-700eV by employing the independent atom model (IAM) together with the relativistic partial waves. The atom is present in an optical potential which is complex, spherically symmetric, and energy dependent. The optical potential of the atom is the sum of the direct static, dynamic polarization, local exchange and modified absorption potentials. The results obtained by using a modified absorption potential show significant improvements on the unmodified absorption potential results. The present results are generally in good agreement with experimental data available. In addition, the present results indicate that the structure of molecule manifests the observable effects on electron-molecule scattering.

A sequential decay model is used to study isoscaling, i.e. the factorization of the isotope ratios from sources of different isospins and sizes over a broad range of excitation energies, into fugacity terms of proton and neutron number, R21(N,Z) = Y2(N,Z)/Y1(N,Z) = Ce(αN+βZ). It is found that the isoscaling parameters α and β have a strong dependence on the isospin difference of equilibrated source and excitation energy, no significant influence of the source size on α and β has been observed. It is found that α and β decrease with the excitation energy and are linear functions of 1/T and Δ(Z/A)2 or Δ(N/A)2 of the sources. Symmetry energy coefficient Csym is constrained from the relationship of α and source Δ(Z/A)2, β and source Δ(N/A)2.

Ne and Mg isotope chains are investigated based on constrained calculations in the framework of a deformed relativistic mean-field (RMF) model with the NL075 parameter set. The calculated quadrupole deformation and binding energy are compared with other theoretical results as well as the available experimental data. It shows that the calculated deformations of Ne and Mg with the NL075 are more accurate than those obtained with the NL-SH. It is predicted that 19,29,32Ne and 20,31Mg maybe have a triaxial deformation and 25−28Ne and 27−30Mg exhibit a shape coexistence probably. The closure effect of neutron number N=8 for 20Mg is predicted to be very weak.

Distribution of the parallel momentum of $^{28}$Si fragments from the breakup of 30.7 MeV/nucleon $^{29}$P has been measured on C targets. The distribution has the FWHM with the value of 110.5 $\pm$ 23.5 MeV/c which is consistent quantitatively with Galuber model calculation assuming by a valence proton in $^{29}$P. The density distribution is also predicted by Skyrme-Hartree-Fock calculation. Results show that there might exist the proton-skin structure in $^{29}$P., Comment: 4 pages, 4 figures

We analyze in detail the numerical results of superheavy nuclei in deformed relativistic mean-field model and deformed Skyrme–Hartree–Fock model. The common points and differences of both models are systematically compared and discussed. Their consequences on the stability of superheavy nuclei are explored and explained. The theoretical results are compared with new data of superheavy nuclei from GSI and from Dubna and reasonable agreement is reached. Nuclear shell effect in superheavy region is analyzed and discussed. The spherical shell effect disappears in some cases due to the appearance of deformation or superdeformation in the ground states of nuclei, where valence nucleons occupy significantly the intruder levels of nuclei. It is shown for the first time that the significant occupation of valence nucleons on the intruder states plays an important role for the ground state properties of superheavy nuclei. Nuclei are stable in the deformed or superdeformed configurations. We further point out that one cannot obtain the octupole deformation of even-even nuclei in the present relativistic mean-field model with the σ, ω and ρ mesons because there is no parityviolating interaction and the conservation of parity of even-even nuclei is a basic assumption of the present relativistic mean-field model.

A candidate for proton halo nucleus 23Al is investigated based on the constrained calculations in the framework of the deformed relativistic mean field (RMF) model with the NL075 parameter set. It is shown by the constrained calculations that the ground state of 23Al has a large deformation that corresponds to the prolate shape. With that large deformation, the non-constrained RMF calculation predicts that there appears an inversion between the 2s1/2 [211] and 1d5/2 [202] shells. The valence proton of 23Al is weakly bound and occupies 2s1/2 [211] and 1d5/2 [202] with the weights of 56% and 29%, respectively. The calculated RMS radius for matter is in agreement with the experimental one. It is also predicted that the difference between the proton RMS radius and the neutron one is very large. This suggests that there exists a proton halo in 23Al.

The structures of two couples of mirror nuclei 17F and 17O, 17Ne and 17N in the ground state and in the first excited state are investigated using the relativistic mean-field approach. Two-proton halo in 17Ne in the first excited state and in the ground state and two-neutron halo in 17N in the first excited state are suggested. Meanwhile, one-proton halo in 17F in the first excited state and one-neutron halo in 17O in the first excited state are also suggested. The skin structure appears in 17F and 17N in the ground state.

We illustrate typical experimental reaction cross sections sigma(R) which have obtained on RIBLL at Heavy Ion Research Facility of the Institute of Modern Physics (IMP) at Lanzhou. The corresponding nuclear radii are extracted from the measured experimental sigma(R) using the Glauber model. Meanwhile, theoretical nuclear radii are also calculated using Relativistic density-dependent Hartree and spherical relativistic mean-field theory with Pauli blocking. For comparison, the nuclear radii of these nuclei are also calculated using the empirical radius format in which the deformation has been taken into account. From the given experimental and theoretical nuclear radii, we suggest that there may exist proton halo structure in Al-23, P-27 and may exist proton skin structure in Al-24. We also End that the deformation plays a great role to the nuclear radii.

Properties of nuclei N-13,N-15 and B-9 are investigated in the relativistic mean-field theory with NLZ and NL3 force parameters. The calculated binding energies are very close to the experimental ones. The calculations show that the first excited state (1p(1/2)) in B-9, the first excited state (2s(1/2)) in N-13 and the second excited state (2s(1/2)) in N-15 are weakly bound. In particular, for N-13 and N-15, the proton density distributions in the two above excited states have a long tail and the rms radii of the last proton are greatly larger compared with their respective matter radii. It is predicted that a proton halo exists in the first excited state of N-13 and in the second excited state of N-15, respectively. It also indicates that the first excited state in B-9 is a proton skin state.

Measurements of the total reaction cross sections (sigma (R)) for some proton-rich nuclei (N = 11 - 15 isotones) on a carbon target at intermediate energies have been performed on the Radioactive Ion Beam Line of the Heavy Ion Research Facility in Lanzhou. A larger enhancement of sigma (R) for P-27 has been observed than for its neighbours. Evidence for a proton halo in P-27 has been revealed in the Glauber analysis of the total reaction cross sections in terms of the difference factor d.

Hard photon emitted from energetic heavy ion collisions is of very interesting since it, does not, experience the late-stage nuclear interaction, therefore it is useful to explore the early-stage information of matter phase. In this work, we ha re, calculated the impact parameter and beam energy dependence for azimuthal asymmetry characterized by directed transverse flow parameter F and elliptic asymmetry coefficient nu 2, of direct photons and the corresponding free protons in intermediate energy heavy-ion collisions. It is further shown the anti-correlated azimuthal asymmetry between direct, photons and free protons.

Using an isospin-dependent quantum molecular dynamics (IQMD) model, we study the (15)C induced reactions front 30-120 MeV/nucleon systematically. Here the valence neutron of (15)C is assigned at both 1d5/2 and 2s1/2 states respectively in order to study the density effect of reaction mechanism. It is believed that the existent neutron halo structure at the 2s1/2 state of (15)C will affect the light particle emission evidently. In our calculation, the different density distributions of (15)C at two states are calculated by relativistic mean field (RMF) model and introduced in the initiation of IQMD model, respectively. It is found that some observables such as emission fragmentation multiplicity, emission neutron/proton ratio and emission neutrons' kinetic energy spectrum are sensitive to the initial density distribution.