Intermediate Energy Heavy Ion Research Articles

Hundreds-GeV Au ion generation by 1022–24 W cm−2 laser pulses interacting with high-Z grain doped gas

Collision of intermediate-energy heavy ions is an important way to investigate the state of high-density nuclear matter and formation of quark gluon plasmas. In this paper, we demonstrate from two-dimensional particle-in-cell simulations that hundreds-GeV Au79+ ions can be generated by ultrashort ∼1022–24 W cm−2 lasers interacting with high-Z grain doped gas. Under extremely intense laser field, strong γ-ray radiation has resulted in massive laser energy loss, and the invoked radiation reaction trapping of electrons weakens the heavy ion acceleration. However, due to hole-boring acceleration and multi-body expansion acceleration of high-Z grains, the energy conversion efficiency from laser to heavy ions is still up to 32%. Our results might provide an effective routine to carry out the experimental explorations of heavy-ion collisions by using hundreds-petawatt laser facilities.

Effects of cluster correlations on fragment emission in C12+C12 at 50 MeV/nucleon

The effects of cluster correlations have been studied in the $^{12}\mathrm{C}+^{12}\mathrm{C}$ reaction at 50 MeV/nucleon, using three antisymmetrized molecular dynamics (AMD) models, the AMD (AMD/D) without any additional cluster correlations, AMD/D-COALS with nucleon correlations based on a coalescence prescription for light cluster formations with $A\ensuremath{\le}4$, and AMD-cluster with an extended cluster correlation in two-nucleon collision processes and a special treatment for intermediate fragment formation with $A\ensuremath{\le}9$. The angular distributions and energy spectra of fragments have been simulated and compared with the available experimental data. It is found that the cluster correlations take a crucial role to describe the productions of light charged particles (LCPs) and intermediate mass fragments (IMFs), and the AMD-cluster studied here provides a consistent overall reproduction of the experimental data. It is also shown that the significant effects of the secondary decay processes are involved for the fragment production besides the dynamical productions in the AMD stage. Detailed LCP and IMF production mechanisms involved in the intermediate energy heavy ion collisions are discussed.

Investigation of fusion probabilities in the reactions with Cr52,54, Ni64 , and Zn68 ions leading to the formation of Z=120 superheavy composite systems

Background: The formation of superheavy nuclei in fusion reactions is suppressed by a competing quasifission process. The competition between the formation of the compound nucleus and the quasifission depends strongly on the reaction entrance channel. Purpose: The investigation of fission and quasifission processes in the formation of Z=120 superheavy composite systems in the Cr52,54+Cm248 and Zn68+Th232 reactions, and their comparison with the Ni64+U238 reaction at energies in the vicinity of the Coulomb barrier. Methods: Mass-energy distributions of fissionlike fragments formed in the reactions Cr52,54+Cm248 and Zn68+Th232 at energies near the Coulomb barrier were measured using the double-arm time-of-flight spectrometer CORSET. Results: Capture cross sections for the reactions under investigation were measured. The most probable fragment masses and total kinetic energies as well as their variances in dependence on the interaction energy were studied for asymmetric and symmetric fragments. The fusion probabilities were estimated from the analysis of mass-energy distributions. Conclusions: The estimated fusion probability drops down by a factor of 103 in the Cr54+Cm248 reaction compared to the reactions of Ca48 ions with actinides. Among the studied reactions, the Cr54+Cm248 is the most favorable one for the production of the superheavy element with Z=120.1 MoreReceived 3 August 2020Accepted 2 September 2020DOI:https://doi.org/10.1103/PhysRevC.102.044605©2020 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFissionLow & intermediate energy heavy-ion reactionsNuclear fusionPropertiesA ≥ 220Nuclear Physics

Production of Bh266 in the Cm248(Na23,5n)Bh266 reaction and its decay properties

The nuclide Bh266 was produced in the Cm248(Na23,5n)Bh266 reaction at beam energies of 125.9, 130.6, and 135.3 MeV. Decay properties of Bh266 were investigated with a rotating wheel apparatus for α and spontaneous fission (SF) spectrometry under low background conditions attained by a gas-jet transport system coupled to the RIKEN gas-filled recoil ion separator. Based on genetically correlated α−α and α-SF decay chains, a total of 23 chains were assigned to Bh266 and its daughter nuclide Db262 and granddaughter Lr258. The half-life of Bh266 was measured to be T1/122=10.0−1.7+2.6s which is an order of magnitude longer than the literature data. The α-particle energies of Bh266 disperse widely in the range of Eα=8.62–9.40MeV. The maximum production cross section for the Cm248(Na23,5n)Bh266 reaction was determined to be σ=57±14 pb at 130.6 MeV, whereas the upper limit for the Cm248(Na23,4n)Bh267 reaction was σ≤14 pb at 121.2 MeV. These cross sections are discussed by comparing with the literature data as well as the theoretical calculations.1 MoreReceived 11 June 2020Accepted 30 July 2020DOI:https://doi.org/10.1103/PhysRevC.102.024625©2020 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasAlpha decayFissionLow & intermediate energy heavy-ion reactionsNuclear fusionNuclear reactionsPropertiesA ≥ 220Nuclear Physics

Low Density In-Medium Effects on Light Clusters from Heavy-Ion Data.

The modification of the ground state properties of light atomic nuclei in the nuclear and stellar medium is addressed, using chemical equilibrium constants evaluated from a new analysis of the intermediate energy heavy-ion (Xe+Sn) collision data measured by the INDRA Collaboration. Three different reactions are considered, mainly differing by the isotopic content of the emission source. The thermodynamic conditions of the data samples are extracted from the measured multiplicities allowing for a parametrization of the in-medium modification, determined with the single hypothesis that the different nuclear species in a given sample correspond to a unique common value for the density of the expanding source. We show that this correction, which was not considered in previous analyses of chemical constants from heavy-ion collisions, is necessary, since the observables of the analyzed systems show strong deviations from the expected results for an ideal gas of free clusters. This dataset is further compared to a relativistic mean-field model, and seen to be reasonably compatible with a universal correction of the attractive σ-meson coupling.

The Nuclear Equation of State in Heavy Ion Collisions

We present several possibilities offered by the dynamics of intermediate energy heavy ion collisions to investigate the nuclear matter equation of state (EoS) beyond the ground state. In particular the relation between the reaction dynamics and the high density nuclear EoS is discussed by comparing theoretical results with experiments.

Erratum: Constituent quark-light vector mesons effective couplings in a weak background magnetic field [Phys. Rev. D 97 , 014022 (2018)

Received 13 January 2020Accepted 21 January 2020DOI:https://doi.org/10.1103/PhysRevD.101.039902© 2020 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBosonizationHadron-hadron interactionsLow & intermediate energy heavy-ion reactionsParticle interactionsQuark modelStrong interactionParticles & FieldsNuclear Physics

Constraints on EOS from finite nuclei, heavy ion collisions and neutron stars

We present several possibilities offered by nuclear structure, the dynamics of intermediate energy heavy ion collisions and neutron stars to investigate the nuclear matter equation of state (EoS) beyond the ground state. In particular the high density nuclear EoS of asymmetric matter, i.e. the symmetry energy, is discussed.

β and γ bands in N=88 , 90, and 92 isotones investigated with a five-dimensional collective Hamiltonian based on covariant density functional theory: Vibrations, shape coexistence, and superdeformation

A comprehensive systematic study is made for the collective β and γ bands in even-even isotopes with neutron numbers N=88 to 92 and proton numbers Z=62(Sm) to 70 (Yb). Data, including excitation energies, B(E0) and B(E2) values, and branching ratios from previously published experiments are collated with new data presented for the first time in this study. The experimental data are compared to calculations using a five-dimensional collective Hamiltonian (5DCH) based on the covariant density functional theory (CDFT). A realistic potential in the quadrupole shape parameters V(β,γ) is determined from potential energy surfaces (PES) calculated using the CDFT. The parameters of the 5DCH are fixed and contained within the CDFT. Overall, a satisfactory agreement is found between the data and the calculations. In line with the energy staggering S(I) of the levels in the 2γ+ bands, the potential energy surfaces of the CDFT calculations indicate γ-soft shapes in the N=88 nuclides, which become γ rigid for N=90 and N=92. The nature of the 02+ bands changes with atomic number. In the isotopes of Sm to Dy, they can be understood as β vibrations, but in the Er and Yb isotopes the 02+ bands have wave functions with large components in a triaxial superdeformed minimum. In the vicinity of Sm152, the present calculations predict a soft potential in the β direction but do not find two coexisting minima. This is reminiscent of Sm152 exhibiting an X(5) behavior. The model also predicts that the 03+ bands are of two-phonon nature, having an energy twice that of the 02+ band. This is in contradiction with the data and implies that other excitation modes must be invoked to explain their origin.20 MoreReceived 4 July 2018Revised 5 June 2019DOI:https://doi.org/10.1103/PhysRevC.100.044324©2019 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCollective levelsCollective modelsElectromagnetic transitionsLow & intermediate energy heavy-ion reactionsNuclear density functional theoryNuclear spin & parityNucleon induced nuclear reactionsProperties150 ≤ A ≤ 189Nuclear Physics

Erratum: Fusion and quasi-elastic scattering in the Li6,7+Au197 systems [Phys. Rev. C 89 , 024607 (2014)

Received 22 August 2019DOI:https://doi.org/10.1103/PhysRevC.100.039902©2019 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasLow & intermediate energy heavy-ion reactionsNuclear fusionNuclear reactionsTransfer reactionsNuclear Physics

α -spectroscopy studies of the new nuclides Pt165 and Hg170

The new nuclides Pt165 and Hg170 were produced in the reactions Mo92(Kr78,5n) and Ru96(Kr78,4n) at bombarding energies of 418 MeV and 390 MeV, respectively. For Hg170 an α-particle energy of Eα=7590(30)keV and half-life of t1/2=0.08−0.04+0.40ms were deduced, while for Pt165 the corresponding values were 7272(14) keV and 0.26−0.09+0.26ms. Comparison of the reduced α-decay widths with systematics indicates that both α decays are unhindered. Although combining the measured α-decay Q values with extrapolated masses suggests that both new nuclides are unbound to two-proton emission by more than 1 MeV, their α-decay half-lives are too short for this decay mode to compete. Improved data were also obtained for Pt166,167, produced via the Ru96(Kr78,α4n) and Ru96(Kr78,α3n) reactions at bombarding energies of 390 MeV and 418 MeV.Received 13 May 2019DOI:https://doi.org/10.1103/PhysRevC.100.014305©2019 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasAlpha decayLifetimes & widthsLow & intermediate energy heavy-ion reactionsNuclear structure & decaysRare & new isotopesTransfer reactionsProperties150 ≤ A ≤ 189TechniquesNuclear data analysis & compilationParticle sources & targetsRadiation detectorsSpectrometers & spectroscopic techniquesNuclear Physics

Intermediate Energy Reactions Versus Heavy-Ion Fusion: Light Particle Emission and Post-Saddle Friction in the Presence of Deformation Effects**Supported by the National Nature Science Foundation of China under Grant No. 11575044 and the Foundation of Nanjing University of Finance & Economics under Grant No. JGY1859

A decaying nucleus undergoes a change in deformation when it fissions. This affects the particle emission in the fission process. Using the dynamical Langevin model, we investigate the role of deformation in the sensitivity of post-saddle neutrons and light charged particles (LCPs) to the post-saddle friction strength (β) for heavy nuclei 240Am produced with different initial conditions: (i) a low excitation energy E* and a large spin ℓ (provided via a fusion mechanism) and (ii) a high E* and a large ℓ as well as a higher E* but a small ℓ (provided in peripheral and near-central intermediate energy heavy-ion reactions, respectively). It is shown that deformation obviously enhances the sensitivity of post-saddle neutrons to β at intermediate-energy peripheral collisions and that for case (i), the drop of LCPs emission due to deformation makes post-saddle LCPs to be almost insensitive to β, but for case (ii) LCPs still have a significant change with β. Furthermore, we find that post-saddle LCPs display a greater sensitivity to β for near-central collisions than for peripheral collisions. These results suggest that given the deformation effects, to better probe post-saddle dissipation properties with neutrons (LCPs) in experiments, it is best to choose those excited heavy nuclear systems populated in peripheral (near-central) collisions at intermediate energies.

Magnetic field effects on photon emission in intermediate energy heavy-ion collisions

Photon production cross section in heavy-ion collisions is estimated by employing the elementary process of proton-neutron bremsstrahlung in a Boltzmann-Uehling-Uhlenbeck model. With taking the electromagnetic field into account for simulating the reactions, the magnetic effects are considered in different impact parameter regions for the collisions of 14N + 208Pb at incident energy of 40 MeV/nucleon in the laboratory system. We investigated the energy spectra, production rates, and the polar angular distributions of photons. In particular, the directed flow $ v_{1}$ and elliptic flow $ v_{2}$ are extracted for both photons and free nucleons. In contrast with unaffected nucleon flows by the magnetic field, photon flows do display magnetic field effect.

Erratum: Temperature dependence of nuclear fission time in heavy-ion fusion-fission reactions [Phys. Rev. C 96 , 054611 (2017)

Received 25 January 2018DOI:https://doi.org/10.1103/PhysRevC.98.019905©2018 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFissionHydrodynamic modelsLow & intermediate energy heavy-ion reactionsStatistical phenomena & chaosThermal & statistical modelsNuclear Physics

Angular distribution of elastic scattering induced by F17 on medium-mass target nuclei at energies near the Coulomb barrier

The elastic scattering angular distributions were measured for 50- and 59-MeV F17 radioactive ion beam on a Y89 target. The aim of this work is to study the effect of the breakup of the proton halo projectile on the elastic scattering angular distribution. The experimental data were analyzed by means of the optical model with the double-folding São Paulo potential for both real and imaginary parts. The theoretical calculations reproduced the experimental data reasonably well. It is shown that the method of the data analysis is correct. In order to clarify the difference observed at large angles for the 59-MeV incident energy data, Continuum-Discretized Coupled-Channels (CDCC) calculations were performed to consider the breakup coupling effect. It is found that the experimental data show the Coulomb rainbow peak and that the effect of the coupling to the continuum states is not very significant, producing only a small hindrance of the Coulomb rainbow peak and a very small enhancement of the elastic scattering angular distribution at backward angles, suggesting that the multipole response of the neutron halo projectiles is stronger than that of the proton halo systems.2 MoreReceived 29 November 2017DOI:https://doi.org/10.1103/PhysRevC.97.044618©2018 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBreakup reactionsDirect reactionsLow & intermediate energy heavy-ion reactionsNucleon distributionUnstable nuclei induced nuclear reactionsProperties6 ≤ A ≤ 19TechniquesOptical, coupled-channel & distorted wave modelsNuclear Physics

Reinvestigation of the excited states in the proton emitter Lu151 : Particle-hole excitations across the N=Z=64 subshell

The excited states of the proton emitter Lu151 were reinvestigated in a recoil-decay tagging experiment at the Accelerator Laboratory of the University of Jyväskylä (JYFL). The level scheme built on the ground state of Lu151 was updated with five new γ-ray transitions. Large-scale shell model calculations were carried out in the model space consisting of the neutron and proton orbitals 0g7/2, 1d5/2, 1d3/2, 2s1/2, and 0h11/2 with the optimized monopole interaction in order to interpret the experimental level scheme of Lu151. It is found that the excitation energies of states above the 27/2− and 23/2+ isomeric levels in Lu151 can be sensitive to excitations from g7/2 and d5/2 to single-particle orbitals above N=Z=64.Received 11 October 2017DOI:https://doi.org/10.1103/PhysRevC.96.064307©2017 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasElectromagnetic transitionsEnergy levels & level densitiesLow & intermediate energy heavy-ion reactionsNuclear spin & parityNuclear structure & decaysProton emissionShell modelProperties150 ≤ A ≤ 189Nuclear Physics

Erratum: Optimal incident energies for production of neutron-deficient actinide nuclei in the reaction Ni58+U238 [Phys. Rev. C 95 , 044608 (2017)

Received 12 May 2017DOI:https://doi.org/10.1103/PhysRevC.95.059905©2017 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasLow & intermediate energy heavy-ion reactionsNuclear reactionsTransfer reactionsPropertiesA ≥ 220Nuclear Physics

Accurate isotopic fission yields of electromagnetically induced fission of U238 measured in inverse kinematics at relativistic energies

SOFIA (Studies On Fission with Aladin) is a novel experimental program, dedicated to accurate measurements of fission-fragment isotopic yields. The setup allows us to fully identify, in nuclear charge and mass, both fission fragments in coincidence for the whole fission-fragment range. It was installed at the GSI facility (Darmstadt), to benefit from the relativistic heavy-ion beams available there, and thus to use inverse kinematics. This paper reports on fission yields obtained in electromagnetically induced fission of U238.15 MoreReceived 14 February 2017DOI:https://doi.org/10.1103/PhysRevC.95.054603©2017 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFissionLow & intermediate energy heavy-ion reactionsNuclear reactionsPhotonuclear reactionsTechniquesNuclear data analysis & compilationNuclear Physics

Medium effect on the nuclear modification factor of protons and pions in intermediate-energy heavy ion collisions

Nuclear modification factor ($R_{cp}$) of protons and pions are investigated by simulating Au + Au collisions from 0.8 to 1.8$A$ GeV in a framework of an isospin-dependent quantum molecular dynamics (IQMD) model. $R_{cp}$ of protons rises with the increase of \pt~ at different beam energies owing to radial flow and Cronin effect. The rate of increase of \rcp~ is suppressed at higher beam energies. The significant difference of $R_{cp}$ between protons and pions indicates different medium effects between protons and pions. By changing the in-medium nucleon-nucleon cross section, the $R_{cp}$ of protons changes a lot, while the $R_{cp}$ of pions does not. Taking the pion absorption into account, the $R_{cp}$ of pions becomes close to unity without $p_{T}$ dependence after deactivating the reaction $\pi N \rightarrow \Delta$, while there is nearly no change on proton. This suggests that the pion absorption plays a dominant role on pion dynamics and have slight effect for proton dynamics.

Investigation of negative-parity states in Dy156 : Search for evidence of tetrahedral symmetry

An experiment populating low/medium-spin states in Dy156 was performed to investigate the possibility of tetrahedral symmetry in this nucleus. In particular, focus was placed on the low-spin, negative-parity states since recent theoretical studies suggest that these may be good candidates for this high-rank symmetry. The states were produced in the Nd148(C12,4n) reaction and the Gammasphere array was utilized to detect the emitted γ rays. B(E2)/B(E1) ratios of transition probabilities from the low-spin, negative-parity bands were determined and used to interpret whether these structures are best associated with tetrahedral symmetry or, as previously assigned, to octupole vibrations. In addition, several other negative-parity structures were observed to higher spin and two new sequences were established.Received 7 July 2016DOI:https://doi.org/10.1103/PhysRevC.95.014321©2017 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCollective levelsElectromagnetic transitionsLow & intermediate energy heavy-ion reactionsProperties150 ≤ A ≤ 189TechniquesCollective modelsNuclear Physics