最新刊期
卷 0 ， 期 0 ， 2020
- 摘要：Background: In recent years, along with the development of the radioactive ion beam facilities, much progress has been achieved in studies of unstable nuclei. Main discoveries include exotic halo and cluster structures around the drip lines; shell evolution and new magic numbers in unstable nuclei; new effective interactions such as tensor force, three-body forces, new spin-orbit force; new modes of collective motion such as soft giant dipole resonance; multi-step process and strong couplings in nuclear reaction with unstable nuclei. Purpose: This review is focused mainly on the outline of the experimental methods which has been intensively applied to investigate the new aspects of unstable nuclei. Methods: Recently many new techniques have been used to the measurement of the basic properties of the ground state of unstable nuclei. Decay measurement, nuclear reaction at low and intermediate energies, fast beam and zero-degree spectroscopy are also widely used. The special development of these methods related to the study of unstable nuclei has been emphasized. Results and Conclusion: Plenty new phenomena of unstable nuclei were observed, which greatly expanded our studies on nuclear physics. With the development of facilities and experimental techniques, we may expect new experimental data coming soon, which would refine our knowledge of the nuclear physics. Abstract关键词：Unstable nuclei;Nuclear structure;Nuclear reaction;Nuclear detection
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发布时间：2021-03-03 - 摘要：Background: Nucleon-pair correlations play an important role in low-lying states of atomic nuclei. Purpose: The aim is to study empirical proton-neutron interactions and investigate the contribution from spin-aligned proton-neutron pairs (with spin 9 and isospin 0) in low-lying states of 96Cd and 92Pd. Methods: The empirical proton-neutron interaction is obtained by using nuclear binding energies of a few neighboring nuclei and the nuclear shell model. The contribution from spin-aligned proton-neutron pairs in the shell model wave functions is evaluated by using the nucleon-pair approximation with isospin symmetry. Results: The empirical proton-neutron interaction is reasonably consistent with isoscalar interactions calculated by using the shell model. There exists an additional binding energy in both even-even and odd-odd nuclei originated from proton-neutron interactions. Spin-aligned isoscalar pairs play an important role in the 01+ , 21+ , 41+ , 61+ , 121+, 141+and 161+ states of 96Cd and the 01+ , 21+states of 92Pd. For the 01+ and 21+ states, the conventional isovector SD pairs are more relevant. Conclusion: Both isoscalar and isovector nucleon pairs play an important role in low-lying states of N=Z nuclei. This is a consequence of nonorthogonality feature of nucleon-pair basis.Cited关键词：Proton-neutron interaction;T=0 proton-neutron pair;Nucleon-pair approximation
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发布时间：2021-03-03 - 摘要：Background: Nuclear shell model is widely applied in the studies of light and medium-mass nuclei. The ground and excited state energies, electromagnetic properties and ? decay properties of these nuclei can be well understood by solving many body Schr?dinger equation with effective shell-model Hamiltonian in the model space. Purpose: The aim is to introduce the framework of shell model and its application in nuclei. Methods: The nuclear shell model is used to study properties of selected nuclei. Results: In psd region, a new effective shell-model Hamiltonian is introduced. The neutron drip-line of C, N, and O isotopes can be given with such Hamiltonian. The nuclei around A=20 with weakly bound proton are investigated through a modified shell model Hamiltonian. N=Z nucleus is good for studying the effect of proton-neutron pair. 46V and 50Mn have both T=0 and 1 rotational band. 92Pd can be understood under a spin alignment isoscalar scheme of proton-neutron pair. Mirror nuclei around N=Z in fp region can be used for the investigation of charge symmetry breaking effect of nuclear force. Conclusion: Nuclear shell model is proper and useful for the description of light and medium-mass nuclei. Abstract关键词：Nuclear shell model;Light and medium-mass nuclei;Low-lying states;Energy level;Electromagnetic transition;Proton-neutron pair
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发布时间：2021-03-03 - 摘要：Background: The neutron microscopic optical potential is obtained by Green function method through nuclear matter approximation and local density approximation based on the effective Skyrme interaction. The presented Skyrme forces can not satisfactorily describe the nuclear reaction properties. Purpose: In the work, we propose a new set of Skyrme force parameterization of description nuclear reaction properties. Methods: The new Skyrme force parameterization is found by simultaneously fitting the characteristics of nuclear matter, the binding energy, charge radius, the neutron induced reaction cross sections and polarization data. These data include the total cross sections, nonelastic sections, elastic scattering angular distributions and analyzing powers for the target mass range 24≤A≤209 with incident neutron energies below 100 MeV. Results: The obtained Skyrme force is used to predict the neutron-actinide reactions with incident energies below 100 MeV. It is found that the calculations can give a satisfactory description of the experimental data. Conclusion: These results suggest that the obtained Skyrme force parameterization can not only describe the ground state properties, but for some quantities in the nuclear reaction. So, the obtained Skyrme force parameterization can be used to predict those data for the stable or unstable target in the mass range 23≤A≤239 with incident nucleon energies below 100 MeV. Abstract关键词：Neutron microscopic optical potential;Skyrme force parameters;Nuclear reaction properties;Nuclear matter properties
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发布时间：2021-03-03 - 摘要：Background: Quantum phase transition is of great interest in many areas of physics. Purpose: In this work, a new scheme is applied to describe the transitional nuclei with X(5) symmetry, from spherical to axially deformed shape-phase transition. Methods: In this new scheme, the usual SU(3) quadrupole-quadrupole interaction is replaced by an O(6) cubic interaction in the Interacting boson model (IBM). Results: The two X(5) candidates 154Gd and 98Sr nuclei are firstly investigated. The low-lying energy levels and E2 transition rates are calculated and compared with the experimental data. Conclusion: The results show that the new scheme can reasonably describe the experimental low-lying spectrum and the intraband and the interband E2 transitions. The present work is meaningful in understanding the new characteristics of symmetry by the higher order O(6) cubic interaction. Abstract关键词：Interacting boson model (IBM);Quantum phase transitions;Higher-order term
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发布时间：2021-03-03 - 摘要：Background: The interplay between the collective rotation and the quasi-particle alignment is a significant feature of nuclear structure at high spins. The g-factors of intra-band high spin states of the ground rotational band can provide direct and unique information on quasi-particle alignment since the g-factors of the high-j proton and the high-j neutron are positively large and negatively small, respectively. Purpose: The present work was motivated to measure g-factors of the rotational states of the positive parity yrast band in 108Cd and to study the quasi-particle alignment. Methods: High spin states of 108Cd were populated by the fusion-evaporation reaction 76Ge(37Cl,1p4n)108Cd at beam energy of 135 MeV from the HI-13 tandem accelerator at China Institute of Atomic Energy, and the g-factors were determined by the transient-magnetic filed-ion implantation perturbed angular distribution (TMF-IMPAD) method. Results: The measured g-factors of 2+, 4+ state are 0.33(11), 0.18(6), respectively. The h11/2 neutrons align at the 10+ state, which leads to the decrement of the g-factors. And the g7/2 neutrons align gradually from 10+ to 16+, which makes the g-factors increase. Conclusion: The g-factor of the bend head of the anti-magnetic rotation band, 16+ state, was measured and the value is ?0.09(3). Abstract关键词：g-factor;Transient-magnetic filed-ion implantation perturbed angular distribution (TMF-IMPAD) method;108Cd
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发布时间：2021-03-03 - 摘要：Background: The change of hadron properties in nuclear medium is a very active field for both experimental and theoretical research. The study of hypernuclei plays an important role in nuclear physics. Purpose: We aim to study the properties of Lambda hypernuclei and the medium modifications of baryon properties. The quark degrees of freedom are explicitly considered in the model, which enables us to investigate the medium modifications of baryons in a nuclear many-body system and provide a reasonable description of the system in a consistent manner. Methods: We use the Friedberg-Lee (FL) model to describe the nucleon and hyperon in nuclear matter and hypernuclei. The baryon is described as a bound state of three quarks in a nontopological soliton formed by a scalar composite gluon field. The baryons interact through the self-consistent exchange of scalar and vector mesons. The mesons couple directly to the quarks inside the baryons. Results: The properties of baryons are significantly modified in nuclear medium. At normal nuclear matter density, the nucleon radius increases by 13% or so with the parameter Set B, while the Lambda radius increases by 9% or so. The Lambda single-particle energies in hypernuclei are very close to the experimental values. Conclusion: It is shown that the present model is able to provide a reasonable description of Lambda hypernuclei without adjusting parameters, and at the same time it predicts a significant increase of the baryon radius in nuclear medium. Abstract关键词：Friedberg-Lee (FL) model;Nuclear matter;Medium effect;Hypernuclei
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发布时间：2021-03-03 - 摘要：Background: Breakup is an important reaction channel in the scattering of loosely bound nuclei especially at sub-barrier energies. Experimental efforts have been put to study the influence of breakup on sub-barrier fusion. Purpose: In order to explore the breakup effects of weakly bound nuclei on different target nuclei, we systematically analyzed the angular distribution of their elastic scatterings. Methods: The barrier parameters of reaction systems were obtained by the S?o Paulo potential, and the total cross sections were obtained from the experimental angular distribution of elastic scattering. Results: The F(x)s were obtained for weakly and tightly bound projectiles on light, medium-mass and heavy target nuclei, and compared with the universal function F0(x) which has no coupling channels. Conclusion: From the comparison we can conclude that the breakup effect is not important for weakly bound projectiles on the light target nuclei, while it is suppressed on medium-mass and heavy target nuclei above the Coulomb barrier and is enhanced for some weakly bound projectiles at sub-barrier energies. More experiments need to be developed on medium-mass and heavy target nuclei. Abstract关键词：Reaction function;Weakly bound nuclei;Elastic scattering;Dynamic effect
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发布时间：2021-03-03 - 摘要：Background: The investigation of beta-delayed proton decay mode has become a powerful tool to study the proton-rich nuclei and their nuclear structure. Purpose: The aim is to study exotic nuclei with extremely low production rates and purity. Methods: The experiment of beta-delayed proton emission of 37Ca was performed at the First Radioactive Ion Beam Line in Lanzhou (RIBLL). Ions were implanted into a double-sided silicon detector (DSSD), where the subsequent decays were correlated to the preceding implantation under a continuous beam-mode. Results: The energy spectrum of delayed protons from 37Ca B decay, half-life and decay branching ratios were measured. Conclusion: The experimental results are in reasonable agreement with the literature, demonstrating the feasibility of our detection approach and the reliability of our data analysis procedure. This allows for development of more powerful detection arrays and further research on nuclei closer to proton-drip line on the basis of present work.Cited关键词：B-delayed proton emission;Double-sided silicon detector (DSSD);Proton spectrum;Half-life;Decay branching ratio
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发布时间：2021-03-03 - 摘要：Background: In big bang nucleosynthesis (BBN) network, 11B(p,γ)12C reaction is believed to be one of the most important reactions for the production of 12C nucleus, and precise measurement of this reaction rates is helpful to understand the abundance of 12C. At energies of astrophysical interest, direct measurement of 11B(p,γ)12C reaction is very difficult because of the coulomb barrier, but it can be derived by the proton spectroscopic factor of 12C. Elastic transfer reaction is a good tool to extract single nucleon spectroscopic factor because the reaction has same entrance and exit channels and involves only one spectroscopic factor. So the angular distribution of the 12C(11B,12C)11B elastic transfer reaction was chosen to extract the proton spectroscopic factor of 12C. Purpose: This paper’s purpose is to calculate the proton spectroscopic factor of 12C and deduce the astrophysical S(E)-factors and reaction rates of 11B(p,γ)12C direct radiative capture reaction. Methods: The angular distribution of 12C(11B,12C)11B elastic transfer reaction was measured by using the Q3D magnetic spectrograph of HI-13 tandem accelerator and two-dimensional position sensitive silicon detector (2D-PSSD). The proton spectroscopic factor of 12C was then derived by using the distorted wave Born approximation (DWBA) analysis. Results: The proton spectroscopic factor of 12C was determined and then the astrophysical S(E)-factors and reaction rates of 11B(p,γ)12C direct radiative capture reaction were deduced successfully. Conclusion: 12C(11B,12C)11B elastic transfer reaction is a good tool to extract the proton spectroscopic factor of 12C, and then the astrophysical S-factors and reaction rates of 11B(p,γ)12C direct radiative capture reaction could be deduced by using the proton spectroscopic factor of 12C. The BBN network calculation which includes 11B(p,γ)12C is underway. Abstract关键词：Q3D magnetic spectrograph;Angular distribution of elastic transfer reaction;Direct radiative capture reaction;Proton spectroscopic factor;Astrophysical reaction rates
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发布时间：2021-03-03 - 摘要：Background: Nuclear exotic structures become an important hotspot of nuclear physics, especially halo structure and a cluster states of light nuclei. Purpose: Many detailed properties of light nuclei structures are still not clear. To find a powerful way of nuclear structure research is very helpful. Methods: An extension of quantum molecular dynamics model (EQMD) is used for halo structure and ? cluster states of light nuclei. Results: Nuclear matter density distributions with halo structure and ? cluster structure are studied. Binding energy of nuclei with exotic structure is studied. Conclusion: EQMD model is a good tool for studies of nuclear exotic structure. Abstract关键词：Exotic structures;Halo;a cluster;Quantum molecular dynamics (QMD)
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发布时间：2021-03-03 - 摘要：Background: Chemical properties of projectile residues are important in studying the symmetry energy using isobaric yield ratio (IYR) and isoscaling methods. Purpose: The correlation between chemical properties of intermediate mass residues and reaction systems is to be studied. It is hoped that the symmetry energy information can be extracted more precisely. Methods: In the framework of the grand-canonical ensemble theory, the /T difference between two heave-ion reactions, which was labeled as 21/T, was extracted by using isobaric yield ratio difference (IBD) method. Results: By comparing the 21/T among six different combinations 48Ca+9Be/40Ca+9Be, 48Ca+9Be/58Ni+9Be, 64Ni+9Be/40Ca+9Be, 64Ni+9Be/58Ni+9Be, 58Ni+9Be/ 40Ca+9Be, 48Ca+9Be/ 64Ni+9Be, it was proved that /T depends on the reaction system. In different reactions, the values of /T were not fixed. When the double neutron-to-proton ratios (N/Z)21=1.17, 21/T can be approximately a constant. Conclusion: Symmetry energy can be more reasonable in isoscaling and IBD methods, when double neutron-to-proton ratios (N/Z)21=1.17 between two similar reaction system.Cited关键词：Transfer reaction;Distorted wave Born approximation (DWBA);Spectroscopic factors;Reaction rate
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发布时间：2021-03-03 - 摘要：Background: Nuclear spin-orbit interaction is important in understanding magic number and shell structure of finite nuclei. Although it has been extensively studied in nuclear structure, its effect in nuclear reactions was long overlooked. Purpose: To be consistent, same nuclear force should be used in both studies of nuclear structure and nuclear reactions. Heavy-ion collisions provide more freedom to study the detailed properties of in-medium nuclear spin-orbit interaction. Methods: In this proceeding, we summarize our recent studies on introducing nucleon spin degree of freedom and spin-related mean-field potentials from nuclear spin-orbit interaction into IBUU (Isospin-dependent Boltzmann-Uehling-Uhlenbeck) transport model. Results: The spin differential transverse flow is sensitive to the strength of the spin-orbit coupling and serves as a useful probe for in-medium spin-orbit interaction. The difference of the spin differential transverse flow for neutrons and protons can be used to study the isospin dependence of the spin-orbit coupling, while spin differential flow of nucleons with high transverse momentum at different beam energies can be used to exact information of the density dependence of the nuclear spin-orbit interaction. Conclusion: With more spin-related probes proposed in the near future, intermediate-energy heavy-ion collisions may become a useful method in studying in-medium nuclear spin-orbit interaction. Abstract关键词：Heavy-ion collisions;Spin-orbit coupling;IBUU (Isospin-dependent Boltzmann-Uehling-Uhlenbeck) transport model
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发布时间：2021-03-03 - 摘要：Background: The self-consistent Thomas-Fermi approximation has been widely used in atomic and nuclear physics. Many properties of nuclei can be described by the Thomas-Fermi approximation in good agreement with experimental data. Purpose: We studied the non-uniform nuclear matter using the self-consistent Thomas-Fermi approximation with a relativistic mean-field model. Methods: The non-uniform matter was assumed to be composed of a lattice of heavy nuclei surrounded by dripped nucleons. We determined the thermodynamically favored state by minimizing the free energy density with respect to the radius of the Wigner-Seitz cell, while the nucleon distribution in the cell was determined self-consistently in the Thomas-Fermi approximation. Results: A detailed comparison is made between the present results and previous calculations in the Thomas-Fermi approximation with a parameterized nucleon distribution that has been adopted in the widely-used-Shen-EOS (equation of state). Conclusion: It has been found that there is no obvious difference in nucleon distributions at lower densities, while the difference becomes noticeable near the transition density to uniform matter. For thermodynamical quantities, such as the free energy and entropy per baryon, the results of both methods generally agree well with each other. Abstract关键词：Non-uniform nuclear matter;Equation of state
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发布时间：2021-03-03 - 摘要：Background: Chemical properties of projectile residues are important in studying the symmetry energy using isobaric yield ratio (IYR) and isoscaling methods. Purpose: The correlation between chemical properties of intermediate mass residues and reaction systems is to be studied. It is hoped that the symmetry energy information can be extracted more precisely. Methods: In the framework of the grand-canonical ensemble theory, the Dm/T difference between two heave-ion reactions, which was labeled as Dm21/T, was extracted by using isobaric yield ratio difference (IBD) method. Results: By comparing the Dm21/T among six different combinations 48Ca+9Be/40Ca+9Be, 48Ca+9Be/58Ni+9Be, 64Ni+9Be/40Ca+9Be, 64Ni+9Be/58Ni+9Be, 58Ni+9Be/ 40Ca+9Be, 48Ca+9Be/ 64Ni+9Be, it was proved that Dm/T depends on the reaction system. In different reactions, the values of Dm/T were not fixed. When the double neutron-to-proton ratios (N/Z)21=1.17, Dm21/T can be approximately a constant. Conclusion: Symmetry energy can be more reasonable in isoscaling and IBD methods, when double neutron-to-proton ratios (N/Z)21=1.17 between two similar reaction system.Cited关键词：Isobaric yield ratio (IYR);Chemical properties;Grand canonical ensemble theory
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发布时间：2021-03-03 - 摘要：Background: Specific viscosity, defined as the ratio of shear viscosity to entropy density, was found as a probe of phase transition. It was observed that the specific viscosity reaches a local minimum at the critical point for both macroscopic and microscopic systems. In addition, a universal lower boundary was predicted by the AdS/CFT theory. In intermediate energy heavy-ion collisions, the studies on the relationship of specific viscosity and nuclear liquid-gas phase transition are still rare. Purpose: This paper gives a brief review for our calculations of the specific viscosity of nuclear fireball created in head-on Au+Au collisions in intermediate energy, for the study of liquid-gas phase transition. Besides, the influences of nucleon-nucleon cross section and symmetry energy on the specific viscosity are also addressed. Methods: The hot Thomas-Fermi formalism is employed to extract the thermal properties of the nuclear matter which is located in the central region of the collision. Two different methods, the Green-Kubo and Danielewicz’s parameterized formula, are used to evaluate the shear viscosity. Finally the correlation between specific viscosity and temperature or collision energy is presented. Results: In both cases, a local minimum of specific viscosity which has the value of around 10 times of the lower bound is found at certain temperature or beam energy. It is clearly shown that the calculated results are not sensitive to the symmetry energy but strongly influenced by the nucleon-nucleon cross section. Conclusion: Our calculations demonstrate that a local minimum of specific viscosity can be taken as a probe of nuclear liquid-gas phase transition which takes place at around 10 MeV. Furthermore, the lower bound of specific viscosity is still valid for nuclear liquid-gas phase transition. Abstract关键词：Intermediate energy heavy-ion collisions;Liquid-gas phase transition;Quantum molecular dynamics (QMD) model;Specific viscosity
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发布时间：2021-03-03 - 摘要：Background: Heavy ion reaction is a unique method to investigate the high temperature and density nuclear matter in laboratory, and the radial flow is a very important experimental probe. Purpose: This paper aims to obtain the radial flow and freeze-out temperature and then compare them with experimental results. Methods: By simulating the Au+Au collision at 1 A GeV in the Isospin dependent Quantum Molecular Dynamics (IQMD) framework, the Blast-wave model was applied to fitting the proton transverse momentum spectra and getting the radial flow and freeze-out temperature. Results: Results show that the radial flow decreases from central to peripheral collisions, and the value at central collisions is consistent with the FOPI experimental result and other theory results. Additionally, the radial flow profile ? has been analyzed in details and ?=0.336 has been determined in this work. Conclusion: The Blast-wave model can nicely describe the proton transverse momentum spectra, and give a reasonable radial flow value in comparison with the FOPI and EOS experimental results. Varying the flow profile ? leads to a large change on the shape of proton and deuteron spectra, and the value between 0?1 is supported. Abstract关键词：Heavy ion collisions;Centrality;Radial flow;Freeze out temperature;Radial flow profile
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发布时间：2021-03-03 - 摘要：Background: The yield ratio (P/T value) of proton to tritium from D-D nuclear reaction in solid is related to detection angle between direction of emitted particles and that of D ions in solid. Actually, the detection angle is changed by the multiple scattering of D ions with target atom. The P/T value is changed consequently. Purpose: The potential between D ion and target atoms could be derived from this yield ratio P/T in low energy region. Methods: The deuterated targets were obtained by bombarding metal foils with 10?20 keV D+ beam. Then, P/T values were measured in different targets at different energies. Simultaneously, a Monte Carlo computer program was used to simulate the P/T values with different multiple scattering potentials. Results: The simulated P/T values with the universal potential are systematically larger than the experimental results; P/T value is related to the target atomic number (Z). Conclusion: P/T value could be a probe to study inter atomic potential in metal targets. Abstract关键词：D-D nuclear reaction in low energy region;P/T value;Screened potential
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发布时间：2021-03-03 - 摘要：Background: Jet, produced by initial quantum chromodynamics QCD hard scatterings, is one of the important probes to study the properties of strongly-interacting matter because it interacts with the QCD medium and loses its energy when it passes through the QCD medium. Purpose: To understand the mechanism of jet quenching, a complementary study on fully reconstructed jet is essential. Methods: In this work, a multiphase transport model is utilized to study the dijet asymmetry, jet fragmentation function and jet shape. Results: The A Multi-Phase Transport model (AMPT) simulation results can basically describe the experimental data. Jet loses energy significantly for strong interactions between jets and partonic matter. Conclusion: Final dijet asymmetry is driven by both initial dijet asymmetry and partonic jet energy loss. Jet fragmentation function can be decomposed into fragmentation and coalescence parts. Compared with leading jet, the subleading jet shows a larger medium modification for its shapes, especially in central Pb+Pb collisions with a larger dijet asymmetry. Abstract关键词：Heavy-ion collisions;A Multi-Phase Transport model (AMPT);Full jet;Fragmentation function;Jet shape
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发布时间：2021-03-03 - 摘要：Background: The study of the diluted ferromagnetic semiconductors with a curie temperature well above room temperature has been paid too much attention, which has potential applications in spin electronics. Purpose: For a better understanding of the origin of the ferromagnetism, especially in the presence of O vacancies, the microscopic electronic structure and hyperfine fields are required. Methods: An ab initio calculations magnetic hyperfine fields in the Fe doped SnO2 were performed by the Wien2k code embodying the full-potential linearized augmented plane-wave method for two charge states of the impurity that occupies two different cases of the neutral impurity state Fe0and the charged acceptor state Fe1? or Fe2?. The Fe doped SnO2 can provide one or two electrons via oxygen donor vacancies. Results: The present results illustrate clearly that the energy level splitting of the Fe-3d orbit with O vacancies and without O vacancies for the (SnO2)15FeO2+1e and (SnO2)15FeO2+2e valences resulted in the increasing of the unpaired electrons and the leading of Fe atoms into the high spin states, producing the giant magnetic moment. Conclusion: The calculated Fe magnetic moment for the (SnO2)15FeO2+1e is 5μB, which is consistent with the magnetic moment of 5.1μB measured by the M?ssbauer spectroscopy. Abstract关键词：Hyperfine interaction;The first principles;WIEN2k;SnO2;Diluted magnetic semiconductor
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发布时间：2021-03-03 - 摘要：Background: The spallation neutron source can generate pulsed white neutron beam and has the advantages such as very high neutron flux and low thermal power, which is used widely in many fields. One of its applications is for nuclear data measurement. However, up to now, no nuclear data measurement based on the white neutron has been carried out in China due to the lack of the white neutron source. Purpose: The China Spallation Neutron Source (CSNS), which is now under construction, will provide us a good opportunity to do nuclear data measurement with its back-streaming neutron beamline. This beamline can provide very intensive neutron flux and reasonable time resolution of white neutrons which are very suitable for nuclear data measurement. Methods: This paper introduces part of the physical design of the back-streaming neutron beamline, especially the Monte Carlo simulation of the two end-stations’ background and the collimator system. Results and Conclusion: According to the simulation results, the neutron and gamma background in the end-stations are very low. And the beam profile of the CSNS back-streaming white neutron source can be well controlled. With the low intensity of background and well designed beam profile, we can develop very high precision nuclear data measurement with the CSNS back-streaming white neutron source. Abstract关键词：China Spallation Neutron Source (CSNS);White neutron source;Nuclear data measurement;Monte Carlo simulation
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发布时间：2021-03-03 - 摘要：Background: Neutron evaluated data were needed by many researches, e.g., the safety traffic of nuclear reactor, design of new generated reactor and treatment of nuclear waste. Purpose: The photo-neutron source driven by 15-MeV electrons LINAC in Thorium molten salt reactor (TMSR) program was designed for Th-U cycle nuclear data measurement. Methods: The photo-neutron source combined with time of flight (TOF) spectra is the most accurate method in neutron energy measurement, which plays a very important role in thermal and resonance neutron cross section measurement. Results: It locats in Jiading campus of Shanghai Institute of Applied Physics (SINAP). In the first phase, a 15-MeV electron LINAC will be manufactured, and then a more high energy about 100-MeV LINAC will be used for the photo-neutron source. Conclusion: The facility (phase 1) will supply the 5-m TOF path and white spectrum neutron with flux ~104 n?s?1?cm?2 and low energy gamma ray ~1 MeV, and it will be used in neutron cross section measurement and gamma irradiation study. This is the first white neutron source facility designed for TMSR nuclear data measurement. Abstract关键词：Photo-neutron source;Th-U cycle;Nuclear data;Time of Flight (TOF);Neutron detector
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发布时间：2021-03-03 - 摘要：Background: It has already been confirmed that the SCRIT (Self-Confining Radioactive Isotope Ion Target) method can be used for electron scattering experiment for short-lived nuclei. An electron scattering facility consisting of a microtron type electron accelerator (RTM: Racetrack Microtron), an electron storage ring (SR2: SCRIT-equipped RIKEN Storage Ring) and an ISOL (Isotope Separator Online) involving an RI generator, had already been constructed in 2010 at RIKEN Nishina Center to realize electron scattering experiments for short-lived nuclei with SCRIT technique. Purpose: Ions of stable nuclei, 133Cs and 132Xe, were used as targets to evaluate the performance of this facility. Methods: In the testing experiment, the energy of electron beam was set to 150 MeV. The stored electron beam current was ~200 mA with lifetime ~200 min. To determine the achievable luminosity, elastically scattered electrons were measured by a detection system, which consists of a drift chamber, plastic scintillation detectors and two calorimeters. The trajectories and energies of scattered electrons were determined by the drift chamber and two calorimeters. The detector system covers the scattering angle from 25° to 50°. Results: From the vertex distribution and energy loss in the calorimeters of scattered electrons, the number of elastic scattered electrons from target ions was obtained and the luminosity was determined to be nearly 1027 cm?2?s?1 at beam current 200 mA, which is the required luminosity to determine the charge density distribution of the target nucleus. Conclusion: Except for the RI beam generator, the other parts of SCRIT electron scattering facility have been already constructed. The first experiment for this facility will be elastic electron scattering for short-lived Sn isotopes including a doubly magic nucleus 132Sn in 2015. Abstract关键词：RI nuclei;Electron scattering;Electron storage ring;Ion trapping
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发布时间：2021-03-03
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