2012 Vol. 29, No. 2
Display Method:
2012, 29(2): 117-122.
doi: 10.11804/NuclPhysRev.29.02.117
Abstract:
The properties of dense matter are studied within the relativistic meanfield theory. The equation of state (EOS) of dense matter are constructed covering a wide range of temperature, proton fraction, and density for the use of supernova simulations. The relativistic meanfield theory is employed to describe the uniform matter, while the ThomasFermi approximation is adopted to describe the nonuniform matter. The EOS of neutron star matter is discussed with the inclusion of hyperons. It is found that the EOS at high density can be significantly softened by the inclusion of hyperons. The 1S0 superfluidity of Λ hyperons may exist in massive neutron stars.
The properties of dense matter are studied within the relativistic meanfield theory. The equation of state (EOS) of dense matter are constructed covering a wide range of temperature, proton fraction, and density for the use of supernova simulations. The relativistic meanfield theory is employed to describe the uniform matter, while the ThomasFermi approximation is adopted to describe the nonuniform matter. The EOS of neutron star matter is discussed with the inclusion of hyperons. It is found that the EOS at high density can be significantly softened by the inclusion of hyperons. The 1S0 superfluidity of Λ hyperons may exist in massive neutron stars.
2012, 29(2): 123-128.
doi: 10.11804/NuclPhysRev.29.02.123
Abstract:
The nucleonnucleon cross sections in symmetric nuclear matter were investigated in the framework of the extended Brueckner-Hartree-Fock(BHF) approach with Argonne V14 two body interaction. The influences of the ground state correlation and the rearrangement contribution of the threebody force (TBF) on the cross section have been obtained and discussed separately for identical and nonidentical nucleon collisions. It is shown that the magnitudes of the cross section are increased by the effects of the ground state correlation in low momentum transfers，and are suppressed in medium with increasing density when the rearrangement contribution of the TBF force is considered.
The nucleonnucleon cross sections in symmetric nuclear matter were investigated in the framework of the extended Brueckner-Hartree-Fock(BHF) approach with Argonne V14 two body interaction. The influences of the ground state correlation and the rearrangement contribution of the threebody force (TBF) on the cross section have been obtained and discussed separately for identical and nonidentical nucleon collisions. It is shown that the magnitudes of the cross section are increased by the effects of the ground state correlation in low momentum transfers，and are suppressed in medium with increasing density when the rearrangement contribution of the TBF force is considered.
2012, 29(2): 129-132.
doi: 10.11804/NuclPhysRev.29.02.129
Abstract:
In the framework of the modified Fisher model， correlations between the symmetryenergy coefficient in semiclassical mass formula to temperature (asym/T) and the isobaric yield ratio in Heavyion collisions are established. asym/Tof neutronrich fragments are extracted using these correlations. It is found that the Coulombenergy term has little effect on asym/T of fragments， while the reference isobars adopted have great influence on the extracted a sym/T of fragments.
In the framework of the modified Fisher model， correlations between the symmetryenergy coefficient in semiclassical mass formula to temperature (asym/T) and the isobaric yield ratio in Heavyion collisions are established. asym/Tof neutronrich fragments are extracted using these correlations. It is found that the Coulombenergy term has little effect on asym/T of fragments， while the reference isobars adopted have great influence on the extracted a sym/T of fragments.
2012, 29(2): 133-138.
doi: 10.11804/NuclPhysRev.29.02.133
Abstract:
Three different collision modes ( Bellybelly， Bellytip and Tiptip) of the deformed uranium nucleus 238U bombarding the deformed 238U in strongly damped reaction at the incident energy 980 MeV has been investigated based on the improved quantum molecular dynamics (ImQMD) model. The formation and properties of the formed composite system during the reaction process were carefully studied including the lifetime， the shape configuration and the angular distribution of primary fragment. It was found that the Bellytip mode is suitable for producing the superheavy fragments， and the composite system has the longest lifetime in this mode.
Three different collision modes ( Bellybelly， Bellytip and Tiptip) of the deformed uranium nucleus 238U bombarding the deformed 238U in strongly damped reaction at the incident energy 980 MeV has been investigated based on the improved quantum molecular dynamics (ImQMD) model. The formation and properties of the formed composite system during the reaction process were carefully studied including the lifetime， the shape configuration and the angular distribution of primary fragment. It was found that the Bellytip mode is suitable for producing the superheavy fragments， and the composite system has the longest lifetime in this mode.
2012, 29(2): 139-144.
doi: 10.11804/NuclPhysRev.29.02.139
Abstract:
The neutronneutron (nn) quasifree scattering (QFS) at 25.0 MeV and nn final state interaction (FSI) at 17.4 MeV in the nd breakup reaction were studied in this work. First， the absolute breakup cross section was measured with an accuracy of <5 % in the nn QFS. The measured data was analyzed by MonteCarlo simulation based on modern realistic NN potentials (CDBonn， Argonne ??18， Nijm I and II). The measured data exceeds the theoretical prediction based on CDBonn by (16.0±4.6%). Second， the proton emission spectrum around 0° was measured in the nd breakup reaction at 17.4 MeV with kinematical incomplete setup. The data was analyzed by MonteCarlo simulation based on CDBonn. The nn scattering length determined in this work was a nn=（-16.8±0.6） fm.
The neutronneutron (nn) quasifree scattering (QFS) at 25.0 MeV and nn final state interaction (FSI) at 17.4 MeV in the nd breakup reaction were studied in this work. First， the absolute breakup cross section was measured with an accuracy of <5 % in the nn QFS. The measured data was analyzed by MonteCarlo simulation based on modern realistic NN potentials (CDBonn， Argonne ??18， Nijm I and II). The measured data exceeds the theoretical prediction based on CDBonn by (16.0±4.6%). Second， the proton emission spectrum around 0° was measured in the nd breakup reaction at 17.4 MeV with kinematical incomplete setup. The data was analyzed by MonteCarlo simulation based on CDBonn. The nn scattering length determined in this work was a nn=（-16.8±0.6） fm.
2012, 29(2): 145-148.
doi: 10.11804/NuclPhysRev.29.02.145
Abstract:
Ce was produced by bombarding an enriched target of 92Mo with 187 MeV 40Ca beam and studiedby using a heliumjet fast tape transport system in combination with X-γ and γ-γ coincidencemeasurements. An EC/β+ decay scheme of 126Ce was proposed for the first time. A group of lowlying states associated with the lowspin isomer in 126La feeding by β decay was possibly from the groundstate EC/β+ decay of 126Ce with the measured half-life 12(4) s. Another group of lowlying states associated with the highspin isomer in 126La feeding by β decay was possibly from a highspin isomer EC/β+ decay of 126Ce with the measured half-life 57(9) s. However， the physical reason for the existence of a highspin isomer in even-even nucleus 126Ce is still an open problem.
Ce was produced by bombarding an enriched target of 92Mo with 187 MeV 40Ca beam and studiedby using a heliumjet fast tape transport system in combination with X-γ and γ-γ coincidencemeasurements. An EC/β+ decay scheme of 126Ce was proposed for the first time. A group of lowlying states associated with the lowspin isomer in 126La feeding by β decay was possibly from the groundstate EC/β+ decay of 126Ce with the measured half-life 12(4) s. Another group of lowlying states associated with the highspin isomer in 126La feeding by β decay was possibly from a highspin isomer EC/β+ decay of 126Ce with the measured half-life 57(9) s. However， the physical reason for the existence of a highspin isomer in even-even nucleus 126Ce is still an open problem.
2012, 29(2): 149-153.
doi: 10.11804/NuclPhysRev.29.02.149
Abstract:
The radiative and pureleptonic decays of Bcmesons are of hadrons uncertainty in theoretical calculations. Using three types of the Bc meson wave functions which describe the characteristics of the QCD nonperturbative and by controlling the parameters in them, the uncertainties of Bc meson decay caused by the hadron decay model are studied in detail. The theoretical results show the branching ratios are (1.819 81~3.189 61)×10-5, which are sensitive to the type of wave functions.
The radiative and pureleptonic decays of Bcmesons are of hadrons uncertainty in theoretical calculations. Using three types of the Bc meson wave functions which describe the characteristics of the QCD nonperturbative and by controlling the parameters in them, the uncertainties of Bc meson decay caused by the hadron decay model are studied in detail. The theoretical results show the branching ratios are (1.819 81~3.189 61)×10-5, which are sensitive to the type of wave functions.
2012, 29(2): 154-157.
doi: 10.11804/NuclPhysRev.29.02.154
Abstract:
The Betatron oscillation and the synchrotron oscillation for the particles are effected by the dipole field perturbation and the cooling effect. Both effects are considered in the paper and the synchrotron motion equation of the particle in the synchroton is reduced to the general pendulum equation in the classical mechanics frame. The stabilities of the system caused by dipole field perturbation and cooling are analyzed by using Melnikov method. The thresholds entered a Smale horseshoe chaos are derived in detail and the stability conditions for the system caused by dipole field perturbation and cooling are dicussed. The results show that the critical condition or the stability thresholds are related to the system parameters. The chaos or an instability can be avoided or controlled in principle by regulating some parameters of the system.
The Betatron oscillation and the synchrotron oscillation for the particles are effected by the dipole field perturbation and the cooling effect. Both effects are considered in the paper and the synchrotron motion equation of the particle in the synchroton is reduced to the general pendulum equation in the classical mechanics frame. The stabilities of the system caused by dipole field perturbation and cooling are analyzed by using Melnikov method. The thresholds entered a Smale horseshoe chaos are derived in detail and the stability conditions for the system caused by dipole field perturbation and cooling are dicussed. The results show that the critical condition or the stability thresholds are related to the system parameters. The chaos or an instability can be avoided or controlled in principle by regulating some parameters of the system.
2012, 29(2): 158-161.
doi: 10.11804/NuclPhysRev.29.02.158
Abstract:
The principle of design and calculation of the power synthesis in the solidstate amplifier are described in this paper. The working frequency of the synthesizer is 80.5 MHz. The output continuous wave power is more than 20 kW; The synthesizer power capacity is analyzed. The theoretical calculation results, Computer Simulation Technology (CST) simulated results are compared with the measured results of the actual 3 dB couplers. The analysis of the measured results and CST calculated results shows that the simulation is in agreement with the measurement results which meet the design requirements of the solidstate amplifier. Except the coupling coefficient, the isolation, the VSWR and other parameters are better than the design target. When the output power is 20 kW, the sampling waveform has no deform and the temperature of the synthesizer is stable.
The principle of design and calculation of the power synthesis in the solidstate amplifier are described in this paper. The working frequency of the synthesizer is 80.5 MHz. The output continuous wave power is more than 20 kW; The synthesizer power capacity is analyzed. The theoretical calculation results, Computer Simulation Technology (CST) simulated results are compared with the measured results of the actual 3 dB couplers. The analysis of the measured results and CST calculated results shows that the simulation is in agreement with the measurement results which meet the design requirements of the solidstate amplifier. Except the coupling coefficient, the isolation, the VSWR and other parameters are better than the design target. When the output power is 20 kW, the sampling waveform has no deform and the temperature of the synthesizer is stable.
2012, 29(2): 162-168.
doi: 10.11804/NuclPhysRev.29.02.162
Abstract:
The principle of time of flight (TOF) positron emission tomography (PET) and a brief review of the history of TOF-PET are introduced. The factors influencing the time resolution of a TOF-PET scanner are presented， especially focus on the intrinsic properties of scintillators and frontend electronics. Challenges and achievements of the structure of data organization and image reconstruction are reviewed. Finally， the benefits of TOF-PET on image quality improvement and tumor detection are emphasized.
The principle of time of flight (TOF) positron emission tomography (PET) and a brief review of the history of TOF-PET are introduced. The factors influencing the time resolution of a TOF-PET scanner are presented， especially focus on the intrinsic properties of scintillators and frontend electronics. Challenges and achievements of the structure of data organization and image reconstruction are reviewed. Finally， the benefits of TOF-PET on image quality improvement and tumor detection are emphasized.
2012, 29(2): 169-172.
doi: 10.11804/NuclPhysRev.29.02.169
Abstract:
To detect the absolute neutron flux in a weak neutron field and restricted space， the fission fragment trapping detector was fabricated and the properties of the detector were studied. In this paper， the detector and shielding chamber used in neutron detection were described and the experimental measurements of the fission rate in specific condition were performed with the detection system and the result has been compared with that obtained by fission chamber. The influence of the shielding chamber on the measured results was analyzed.
To detect the absolute neutron flux in a weak neutron field and restricted space， the fission fragment trapping detector was fabricated and the properties of the detector were studied. In this paper， the detector and shielding chamber used in neutron detection were described and the experimental measurements of the fission rate in specific condition were performed with the detection system and the result has been compared with that obtained by fission chamber. The influence of the shielding chamber on the measured results was analyzed.
2012, 29(2): 173-177.
doi: 10.11804/NuclPhysRev.29.02.173
Abstract:
The feasible study of Monte Carlo simulation of lowenergy nuclear reaction was performed based on GEANT4. The reaction channel 6Li(n， α)3H， simulated insufficiently in the old version Geant4， can be given correct results in the new version (version 4.9.4). New cross section library was added into the program. The study of several nuclear reaction channels shows that the cross sections， the secondary particle energies and the branching ratios are consistent with the experimental values. For doped 6Li materials， the comparison of thermal neutrons detection efficiencies of experimental results， MCNP and GEANT4 simulations， shows that the simulations are reasonable. From the studies above， it is feasible to simulate the 6Li(n， α)3H reaction with GEANT4. It will provide helpful information for the further study of the position resolution of scintillation neutron detector.
The feasible study of Monte Carlo simulation of lowenergy nuclear reaction was performed based on GEANT4. The reaction channel 6Li(n， α)3H， simulated insufficiently in the old version Geant4， can be given correct results in the new version (version 4.9.4). New cross section library was added into the program. The study of several nuclear reaction channels shows that the cross sections， the secondary particle energies and the branching ratios are consistent with the experimental values. For doped 6Li materials， the comparison of thermal neutrons detection efficiencies of experimental results， MCNP and GEANT4 simulations， shows that the simulations are reasonable. From the studies above， it is feasible to simulate the 6Li(n， α)3H reaction with GEANT4. It will provide helpful information for the further study of the position resolution of scintillation neutron detector.
2012, 29(2): 178-183.
doi: 10.11804/NuclPhysRev.29.02.178
Abstract:
Based on the fully relativistic configuration interaction method, theoretical calculations are carried out for the dielectronic recombination (DR) rate coefficients of Xe8+ ions in the temperature region from 0.1 to 1 650 eV. The comparison of the DR rate coefficients from 4s, 4p and 4d subshell excitations shows that 4d subshell excitation dominates in the whole temperature region. The contribution from 4p subshell excitation is very important at temperature above 10 eV and the contributions from 4s subshell excitation is lower than 7.5% in the whole temperature region. Similarly, the comparison of the DR rate coefficients through △n=0, 1 and 2 core excitation shows that the contribution from △n=2 core excitation can not be neglected, the contributions from n′＞15 can also not be neglected. The DR rate coefficients of △n=0, 1 and 2 core excitation and the total DR rate coefficients are fitted with some parameters, which are in good agreement with theoretical calculations values (within 1% difference). The total DR rate coefficients are greater than radiative recombination (RR) and threebody recombination (TBR) rate coefficients at temperature above 1 eV. Therefore, the DR process can strongly influence the ionization balance of laser produced xenon plasmas.
Based on the fully relativistic configuration interaction method, theoretical calculations are carried out for the dielectronic recombination (DR) rate coefficients of Xe8+ ions in the temperature region from 0.1 to 1 650 eV. The comparison of the DR rate coefficients from 4s, 4p and 4d subshell excitations shows that 4d subshell excitation dominates in the whole temperature region. The contribution from 4p subshell excitation is very important at temperature above 10 eV and the contributions from 4s subshell excitation is lower than 7.5% in the whole temperature region. Similarly, the comparison of the DR rate coefficients through △n=0, 1 and 2 core excitation shows that the contribution from △n=2 core excitation can not be neglected, the contributions from n′＞15 can also not be neglected. The DR rate coefficients of △n=0, 1 and 2 core excitation and the total DR rate coefficients are fitted with some parameters, which are in good agreement with theoretical calculations values (within 1% difference). The total DR rate coefficients are greater than radiative recombination (RR) and threebody recombination (TBR) rate coefficients at temperature above 1 eV. Therefore, the DR process can strongly influence the ionization balance of laser produced xenon plasmas.
2012, 29(2): 184-188.
doi: 10.11804/NuclPhysRev.29.02.184
Abstract:
By using an incident electron beam with the high current and high energy， the guiding effect of the bended macroscopic quartz tube for the electron beam has been investigated. The angular distributions of outgoing electrons depending on the current and energy of incident electrons were measured. The dependences of electron transmitted fraction on energy and current of incident electrons are also shown. As the incident electron energy increasing， the electron transmitted fraction increases， but it decreases while the incident electron current increasing. The results have been compared with the present data. This work presents， the process of guiding electrons is essentially different from that of guiding highly charged ions， the guiding electron beam was caused by both elastic and inelastic collisions between electrons and inner walls of quartz tube， rather than selforganized charging effect on the surface of inner wall of quartz tube.
By using an incident electron beam with the high current and high energy， the guiding effect of the bended macroscopic quartz tube for the electron beam has been investigated. The angular distributions of outgoing electrons depending on the current and energy of incident electrons were measured. The dependences of electron transmitted fraction on energy and current of incident electrons are also shown. As the incident electron energy increasing， the electron transmitted fraction increases， but it decreases while the incident electron current increasing. The results have been compared with the present data. This work presents， the process of guiding electrons is essentially different from that of guiding highly charged ions， the guiding electron beam was caused by both elastic and inelastic collisions between electrons and inner walls of quartz tube， rather than selforganized charging effect on the surface of inner wall of quartz tube.
2012, 29(2): 189-195.
doi: 10.11804/NuclPhysRev.29.02.189
Abstract:
Signaling factors usually play an important role in bystander effect. In this work， human hepatoma QGY7703 cells in vitro were irradiated with highLET carbon ions. Concentrations of signaling factors such as TGF-β1 and NO were measured in the media of the irradiated QGY-7703 cells at different time points after irradiation. The conditioned media harvested at various times postirradiation were transferred to human hepatocyte L02 cells as bystander cells and then the influence of the conditioned media on survival fraction and cell viability of the bystander cells were determined. The results show that the irradiated cells regulate the concentration of the signaling factors released nearby themselves temporally and spatially， and the bystander cells response to the signaling factors differentially according to the concentration change. This work provides new basic data for exploring the bystander effect， especially caused by highLET radiation.
Signaling factors usually play an important role in bystander effect. In this work， human hepatoma QGY7703 cells in vitro were irradiated with highLET carbon ions. Concentrations of signaling factors such as TGF-β1 and NO were measured in the media of the irradiated QGY-7703 cells at different time points after irradiation. The conditioned media harvested at various times postirradiation were transferred to human hepatocyte L02 cells as bystander cells and then the influence of the conditioned media on survival fraction and cell viability of the bystander cells were determined. The results show that the irradiated cells regulate the concentration of the signaling factors released nearby themselves temporally and spatially， and the bystander cells response to the signaling factors differentially according to the concentration change. This work provides new basic data for exploring the bystander effect， especially caused by highLET radiation.
2012, 29(2): 196-201.
doi: 10.11804/NuclPhysRev.29.02.196
Abstract:
Clustered DNA damage which caused by high LET heavy ion radiation can lead to mutation, tumorigenesis and apoptosis. Promoting apoptosis of cancer cells is always the basis of cancer treatment. Clustered DNA damage has been the hot topic in radiobiology. The detect method is diversity, but there is not a detail and complete protocol to analyze clustered DNA damage. In order to provide reference for clustered DNA damage in the radiotherapy study, the clustered DNA damage characteristics, the latest progresses on clustered DNA damage and the detecting methods are reviewed and discussed in deteil in this paper.
Clustered DNA damage which caused by high LET heavy ion radiation can lead to mutation, tumorigenesis and apoptosis. Promoting apoptosis of cancer cells is always the basis of cancer treatment. Clustered DNA damage has been the hot topic in radiobiology. The detect method is diversity, but there is not a detail and complete protocol to analyze clustered DNA damage. In order to provide reference for clustered DNA damage in the radiotherapy study, the clustered DNA damage characteristics, the latest progresses on clustered DNA damage and the detecting methods are reviewed and discussed in deteil in this paper.
2012, 29(2): 202-207.
doi: 10.11804/NuclPhysRev.29.02.202
Abstract:
The paper presents feature parameter analysis and processing in fission timedependent signal of induced uranium components based on BPNeural Networks through the analysis of the measuring principle and signal characteristics of induced uranium components fission signal. The auto correlation functions and cross correlation functions are calculated by using unbiased estimate， and then the feature parameters of fission signal in different status are extracted by using feature abstraction method， comparative method and derivative method， and then applied to training and prediction by means of BPneural networks based on pattern recognition. Theoretical analysis and the results show that， it is effective to obtain feature parameters of induced uranium component fission signal via comparative method and derivative method. UsingBP neural network to recognize patter of fission signal， we got good results that verified the effectiveness and reasonability of the method.
The paper presents feature parameter analysis and processing in fission timedependent signal of induced uranium components based on BPNeural Networks through the analysis of the measuring principle and signal characteristics of induced uranium components fission signal. The auto correlation functions and cross correlation functions are calculated by using unbiased estimate， and then the feature parameters of fission signal in different status are extracted by using feature abstraction method， comparative method and derivative method， and then applied to training and prediction by means of BPneural networks based on pattern recognition. Theoretical analysis and the results show that， it is effective to obtain feature parameters of induced uranium component fission signal via comparative method and derivative method. UsingBP neural network to recognize patter of fission signal， we got good results that verified the effectiveness and reasonability of the method.
2012, 29(2): 208-215.
doi: 10.11804/NuclPhysRev.29.02.208
Abstract:
Takeing 135Xe produced by neutron induced fission of 235U as an example, the evaluation method for fission yield was introduced using the all experimental data available. The evaluation procedure includes the experimental data collection, correction, evaluation, error assessment and data analysis. The study of the uncertainty covariance, application of semiempirical theoretical calculation and the yield energydependence of 135Xe in the incident energy range 0~20 MeV were emphasized in this work.
Takeing 135Xe produced by neutron induced fission of 235U as an example, the evaluation method for fission yield was introduced using the all experimental data available. The evaluation procedure includes the experimental data collection, correction, evaluation, error assessment and data analysis. The study of the uncertainty covariance, application of semiempirical theoretical calculation and the yield energydependence of 135Xe in the incident energy range 0~20 MeV were emphasized in this work.
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