2019 Vol. 36, No. 4
Display Method:
2019, 36(4): 395-399.
doi: 10.11804/NuclPhysRev.36.04.395
Abstract:
We report the results of the energy dependence of specific heat (CV) of hadronic matter in a multiphase transport (AMPT) model and compared with the experimental results from Ref.[PhysRevC.94.044901]. The temperature high order fluctuations in Au+Au collisions in AMPT model are also reported. CV is a thermodynamic quantity that characterizes the equation of state of the system. For a system undergoing phase transition, CV is expected to diverge at the critical point. Fluctuations of temperature are sensitive observables to probe the QCD critical point. The CV is extracted by analyzing the data on event-by-event mean transverse momentum (<pT>). The <pT> distributions in finite pT ranges are converted to distributions of effective temperature (Teff). The CV is extracted from the Teff distributions. The fluctuations of temperature are measured by calculating the high order cumulants of the Teff distributions. We find that both CV and high order cumulants of the temperature show monotonic distributions in energy dependence, which is expected that there is no phase transition critical point in the AMPT model. At low energies, a sharp drop of CV from the experimetal results is observed and it deviates from the AMPT results. The AMPT model can provide a non-critical background, which can provides a good reference for comparison with experimental results to search for the QCD critical point.
We report the results of the energy dependence of specific heat (CV) of hadronic matter in a multiphase transport (AMPT) model and compared with the experimental results from Ref.[PhysRevC.94.044901]. The temperature high order fluctuations in Au+Au collisions in AMPT model are also reported. CV is a thermodynamic quantity that characterizes the equation of state of the system. For a system undergoing phase transition, CV is expected to diverge at the critical point. Fluctuations of temperature are sensitive observables to probe the QCD critical point. The CV is extracted by analyzing the data on event-by-event mean transverse momentum (<pT>). The <pT> distributions in finite pT ranges are converted to distributions of effective temperature (Teff). The CV is extracted from the Teff distributions. The fluctuations of temperature are measured by calculating the high order cumulants of the Teff distributions. We find that both CV and high order cumulants of the temperature show monotonic distributions in energy dependence, which is expected that there is no phase transition critical point in the AMPT model. At low energies, a sharp drop of CV from the experimetal results is observed and it deviates from the AMPT results. The AMPT model can provide a non-critical background, which can provides a good reference for comparison with experimental results to search for the QCD critical point.
2019, 36(4): 400-407.
doi: 10.11804/NuclPhysRev.36.04.400
Abstract:
Based on the Improved Quantum Molecular Dynamics model (ImQMD), the difference of central collision in experiment and theory for low-intermediate energy heavy ion collisions is investigated. By analyzing the two kinds of central collisions, we find there is 50% difference on the charge distribution, and also on its average kinetic energy for heavier fragments, especially at the beam energy of 50 MeV/u. While, for the coalescence invariant neutron proton yield ratio, the calculations show there are about 5% ~ 15% difference. Our results evidence that the impact parameter smearing effects must be considered for tightly constraining the nuclear equation of state and the in-medium nucleon-nucleon cross sections by heavy ion collision.
Based on the Improved Quantum Molecular Dynamics model (ImQMD), the difference of central collision in experiment and theory for low-intermediate energy heavy ion collisions is investigated. By analyzing the two kinds of central collisions, we find there is 50% difference on the charge distribution, and also on its average kinetic energy for heavier fragments, especially at the beam energy of 50 MeV/u. While, for the coalescence invariant neutron proton yield ratio, the calculations show there are about 5% ~ 15% difference. Our results evidence that the impact parameter smearing effects must be considered for tightly constraining the nuclear equation of state and the in-medium nucleon-nucleon cross sections by heavy ion collision.
2019, 36(4): 408-413.
doi: 10.11804/NuclPhysRev.36.04.408
Abstract:
The first excited state plays a significant role for all excited states of nuclei besides the ground state. The first excitation energy which can directly reflect the stability of the nuclei to some extent is one of the most important features of the excited states. Through statistical analysis of the first excitation energies of 2 125 nuclei, one can find that the first excitation energies at the traditional magic number positions are significantly higher than those of the adjacent nuclei, as well as the nuclei with the highest first excited energy of both the isotopic and isotonic chains. For a small number of nuclei significantly deviating from the positions of the traditional magic number, it is also found that their high first excitation energies were the Isobaric Analog States (IAS) of the adjacent nuclei or some mixed levels of fissile nuclei. For the highest first excitation energy of the isotopic and isotonic chains, the number of their spins and parities with 2+ of the first excited state is most up to 42%. For even-even nuclei in the range of mass number 100~200, the first excitation energies can be described by the exponential decay function with the valence nucleon NpNn.
The first excited state plays a significant role for all excited states of nuclei besides the ground state. The first excitation energy which can directly reflect the stability of the nuclei to some extent is one of the most important features of the excited states. Through statistical analysis of the first excitation energies of 2 125 nuclei, one can find that the first excitation energies at the traditional magic number positions are significantly higher than those of the adjacent nuclei, as well as the nuclei with the highest first excited energy of both the isotopic and isotonic chains. For a small number of nuclei significantly deviating from the positions of the traditional magic number, it is also found that their high first excitation energies were the Isobaric Analog States (IAS) of the adjacent nuclei or some mixed levels of fissile nuclei. For the highest first excitation energy of the isotopic and isotonic chains, the number of their spins and parities with 2+ of the first excited state is most up to 42%. For even-even nuclei in the range of mass number 100~200, the first excitation energies can be described by the exponential decay function with the valence nucleon NpNn.
2019, 36(4): 414-418.
doi: 10.11804/NuclPhysRev.36.04.414
Abstract:
The Jinping Underground laboratory for Nuclear Astrophysics(JUNA) group is planing to take the advantage of the ultra-low background of China Jinping Underground Laboartory(CJPL) and a high current accelerator based on an 2.45 GHz ECR ion source to study some key reactions of the nuclear astrophysics at their stellar energies for the first time. The experiments in JUNA project need proton, He+ and He2+ beams with intensities of 10, 10 and 2 emA, respectively. The most challenging part of the design and fabrication of ECR ion source is the production of the He2+ beam with intensities at the level of milliamperes. The traditional particle identification method based on magnetic rigidity is difficult to distinguish the He2+ and H+ ions because of their similar mass-to-charge ratios. Therefore, a novel method using nuclear reactions has been developed in this work for the identification of A/q=2 beam species from the ion source. The result shows that the 2.45 GHz ECR ion source can't produce the He2+ beam with a intensity of milliampere. Based on this result, a 14.5 GHz ECR ion source has been developed which has produced 2 emA He2+ beam successfully.
The Jinping Underground laboratory for Nuclear Astrophysics(JUNA) group is planing to take the advantage of the ultra-low background of China Jinping Underground Laboartory(CJPL) and a high current accelerator based on an 2.45 GHz ECR ion source to study some key reactions of the nuclear astrophysics at their stellar energies for the first time. The experiments in JUNA project need proton, He+ and He2+ beams with intensities of 10, 10 and 2 emA, respectively. The most challenging part of the design and fabrication of ECR ion source is the production of the He2+ beam with intensities at the level of milliamperes. The traditional particle identification method based on magnetic rigidity is difficult to distinguish the He2+ and H+ ions because of their similar mass-to-charge ratios. Therefore, a novel method using nuclear reactions has been developed in this work for the identification of A/q=2 beam species from the ion source. The result shows that the 2.45 GHz ECR ion source can't produce the He2+ beam with a intensity of milliampere. Based on this result, a 14.5 GHz ECR ion source has been developed which has produced 2 emA He2+ beam successfully.
2019, 36(4): 419-425.
doi: 10.11804/NuclPhysRev.36.04.419
Abstract:
The Spectrometer Ring (SRing), which is an important component of the High Intensity heavy-ion Accelerator Facility (HIAF), has to be optimized for the closed orbit correction system. Since the maximum horizontal β function of the isochronous mode (γt=1.43) is very large, the field imperfections and alignment deviations of the magnets will cause large closed orbit distortion (COD), which will result in the distortions of linear optics. Therefore, the closed orbit correction is critical to the operation of SRing. In the simulations, the Singular Value Decomposition (SVD) algorithm is adopted. The repeated correction method is applied and the response matrices are multi-calculated before each correction. The influences of BPM reading errors are analyzed. In addition, the effects of reduced singular values are analytically expressed and simulated. As a result, the closed orbits are corrected to be less than 0.8 mm, and the linear optics is also well optimized.
The Spectrometer Ring (SRing), which is an important component of the High Intensity heavy-ion Accelerator Facility (HIAF), has to be optimized for the closed orbit correction system. Since the maximum horizontal β function of the isochronous mode (γt=1.43) is very large, the field imperfections and alignment deviations of the magnets will cause large closed orbit distortion (COD), which will result in the distortions of linear optics. Therefore, the closed orbit correction is critical to the operation of SRing. In the simulations, the Singular Value Decomposition (SVD) algorithm is adopted. The repeated correction method is applied and the response matrices are multi-calculated before each correction. The influences of BPM reading errors are analyzed. In addition, the effects of reduced singular values are analytically expressed and simulated. As a result, the closed orbits are corrected to be less than 0.8 mm, and the linear optics is also well optimized.
2019, 36(4): 426-432.
doi: 10.11804/NuclPhysRev.36.04.426
Abstract:
In order to meet the needs of the automatic control of the newly developed 400 kV small heavy nuclide accelerator mass spectrometer (AMS) facility of China Institute of Atomic Energy, an automatic control system for the facility was designed and implemented. The article describes the system structure from two aspects of hardware and software, virtual instrument LabWindows/CVI9.0, PLC, database, configuration software, etc., to form a friendly human-computer interaction interface, and improve the reliability of the system. Self-designed gas stripper control with high automation level realizes synchronous monitoring, control of gas flow and vacuum. The combination of the zero indication and target number display of the automatic target change control achieves the target change function more accurately and improves the degree of facility automation. After a long time test, the measurement and control system realize the automatic control and local operation requirements of the accelerator mass spectrometry system.
In order to meet the needs of the automatic control of the newly developed 400 kV small heavy nuclide accelerator mass spectrometer (AMS) facility of China Institute of Atomic Energy, an automatic control system for the facility was designed and implemented. The article describes the system structure from two aspects of hardware and software, virtual instrument LabWindows/CVI9.0, PLC, database, configuration software, etc., to form a friendly human-computer interaction interface, and improve the reliability of the system. Self-designed gas stripper control with high automation level realizes synchronous monitoring, control of gas flow and vacuum. The combination of the zero indication and target number display of the automatic target change control achieves the target change function more accurately and improves the degree of facility automation. After a long time test, the measurement and control system realize the automatic control and local operation requirements of the accelerator mass spectrometry system.
2019, 36(4): 433-440.
doi: 10.11804/NuclPhysRev.36.04.433
Abstract:
It is necessary to measure beam parameters with beam diagnostics detectors for HIMM(Heavy Ion Medical Machine), most of which are interceptive detectors that will be inserted into the center of the beam pipeline while measuring the beam parameters and be pulled out when the measurement is finished. Furthermore, some of the detectors need to be controlled harmonically. In this paper, the architecture of the motion control system is designed and implemented based on the EtherCAT protocol. The client-server software system based on OPC UA protocol is developed and tested with beam. The motion control system of all beam diagnostics detectors has passed the verification of the CFDA(China-Food and Drug Administration) and been running since 2017 with beam. The results show that the system is of high stability and transplantability characters, the control accuracy and control mode can fully meet the application requirements.
It is necessary to measure beam parameters with beam diagnostics detectors for HIMM(Heavy Ion Medical Machine), most of which are interceptive detectors that will be inserted into the center of the beam pipeline while measuring the beam parameters and be pulled out when the measurement is finished. Furthermore, some of the detectors need to be controlled harmonically. In this paper, the architecture of the motion control system is designed and implemented based on the EtherCAT protocol. The client-server software system based on OPC UA protocol is developed and tested with beam. The motion control system of all beam diagnostics detectors has passed the verification of the CFDA(China-Food and Drug Administration) and been running since 2017 with beam. The results show that the system is of high stability and transplantability characters, the control accuracy and control mode can fully meet the application requirements.
2019, 36(4): 441-446.
doi: 10.11804/NuclPhysRev.36.04.441
Abstract:
HIMM (Heavy Ion Medical Machine) is a self-designed and independently developed medical accelerator device in China, the stability and reliability of the whole accelerator control system is higher than that of the industrial system. Ion source gas valve is an important component of ion source to generate beam. The gas flow rate and mixing ratio directly affects the vacuum, ionization efficiency and stability of ion source. This paper introduces the gas control system based on Mitsubishi servo motor and Phoenix PLC for HIMM ion source system. The system structure, hardware composition, PLC program, interface program and data analysis are presented. In order to ensure the stability of the system, hard interlocking with vacuum values and remote switching functions are added to the motion control. The actual test shows that the system runs stably and the positioning accuracy can reach 0.1?, which meets the design requirements.
HIMM (Heavy Ion Medical Machine) is a self-designed and independently developed medical accelerator device in China, the stability and reliability of the whole accelerator control system is higher than that of the industrial system. Ion source gas valve is an important component of ion source to generate beam. The gas flow rate and mixing ratio directly affects the vacuum, ionization efficiency and stability of ion source. This paper introduces the gas control system based on Mitsubishi servo motor and Phoenix PLC for HIMM ion source system. The system structure, hardware composition, PLC program, interface program and data analysis are presented. In order to ensure the stability of the system, hard interlocking with vacuum values and remote switching functions are added to the motion control. The actual test shows that the system runs stably and the positioning accuracy can reach 0.1?, which meets the design requirements.
2019, 36(4): 447-455.
doi: 10.11804/NuclPhysRev.36.04.447
Abstract:
Positron emission tomography (PET) is a technology intensive complex medical product containing thousands of detector and data sampling channels, which leads to difficult debugging, excessive iterations, timeconsuming and high cost in early R&D stage. For solving this problem, a PET electrical simulation system was constructed in the paper based on Gate (Geant4 application for tomographic emission) and MATLAB (matrix laboratory, Mathworks Inc.). Firstly, the annihilation events with TOF (time-of flight) information are recorded by Gate and converted into photon pulse signals using DiSER (digital-single-event-reconstruction) model. The pulses are quantified by ADC (analog-to-digital converter) and transferred to the co-simulation module of FPGA (field programmable gate array) and MATLAB to verify the feasibility of FPGA-based hardware acquisition algorithm. Secondly, the data latched by co-simulation platform is presented to the coincidence processor implementable by FPGA in a pipelined manner to verify the algorithm's validity and optimality. Finally, the proposed simulation model is verified by experiments using a TOF-PET prototype and the Gate-Matlab co-simulation platform presented in the paper can span the development lifecycle of PET, and the basic ideas and principles can be extended to other fields flexibly.
Positron emission tomography (PET) is a technology intensive complex medical product containing thousands of detector and data sampling channels, which leads to difficult debugging, excessive iterations, timeconsuming and high cost in early R&D stage. For solving this problem, a PET electrical simulation system was constructed in the paper based on Gate (Geant4 application for tomographic emission) and MATLAB (matrix laboratory, Mathworks Inc.). Firstly, the annihilation events with TOF (time-of flight) information are recorded by Gate and converted into photon pulse signals using DiSER (digital-single-event-reconstruction) model. The pulses are quantified by ADC (analog-to-digital converter) and transferred to the co-simulation module of FPGA (field programmable gate array) and MATLAB to verify the feasibility of FPGA-based hardware acquisition algorithm. Secondly, the data latched by co-simulation platform is presented to the coincidence processor implementable by FPGA in a pipelined manner to verify the algorithm's validity and optimality. Finally, the proposed simulation model is verified by experiments using a TOF-PET prototype and the Gate-Matlab co-simulation platform presented in the paper can span the development lifecycle of PET, and the basic ideas and principles can be extended to other fields flexibly.
2019, 36(4): 456-461.
doi: 10.11804/NuclPhysRev.36.04.456
Abstract:
In this work, we designed an FPGA-based digital anti-coincidence gamma-ray spectrometer system to reduce the effect of the natural background radiation and Compton scattering on detection of the low-level radioactivity. In this system, the anti-coincidence detector consists of a NaI(Tl) detector with a size of Φ75 mm×75 mm and an annular NaI(Tl) detector (Φ145 mm×95 mm×80 mm), the FPGA and the ADC were employed to sample the pulse signal from the main detector and the annular NaI(Tl) detector synchronously. We designed the related algorithms running in FPGA, such as signal acquisition and caching, anti-coincidence discrimination, and trapezoidal shaping. In the natural background measurement, the digital anti-coincidence gamma-ray spectrometer system reached a count rate of 191.80 cps and a suppression of background radiation coefficient of 2.69. In the 137Cs source irradiation experiment at the center of the front face of the anti-coincidence detector, the peak to total ratio reaches 0.41 and the energy resolution is 6.99%. The peak to total ratio reaches 0.30 and the energy resolution is 7.48% when the 137Cs source is placed in the middle part of the anti-coincidence detector. The experimental results show that the FPGA-based digital anti-coincidence gamma-ray spectrometer system in this paper can reduce the influence of natural background radiation and Compton scattering effectively, and can be used for on-site radioactivity detection and low-level radioactivity measurements.
In this work, we designed an FPGA-based digital anti-coincidence gamma-ray spectrometer system to reduce the effect of the natural background radiation and Compton scattering on detection of the low-level radioactivity. In this system, the anti-coincidence detector consists of a NaI(Tl) detector with a size of Φ75 mm×75 mm and an annular NaI(Tl) detector (Φ145 mm×95 mm×80 mm), the FPGA and the ADC were employed to sample the pulse signal from the main detector and the annular NaI(Tl) detector synchronously. We designed the related algorithms running in FPGA, such as signal acquisition and caching, anti-coincidence discrimination, and trapezoidal shaping. In the natural background measurement, the digital anti-coincidence gamma-ray spectrometer system reached a count rate of 191.80 cps and a suppression of background radiation coefficient of 2.69. In the 137Cs source irradiation experiment at the center of the front face of the anti-coincidence detector, the peak to total ratio reaches 0.41 and the energy resolution is 6.99%. The peak to total ratio reaches 0.30 and the energy resolution is 7.48% when the 137Cs source is placed in the middle part of the anti-coincidence detector. The experimental results show that the FPGA-based digital anti-coincidence gamma-ray spectrometer system in this paper can reduce the influence of natural background radiation and Compton scattering effectively, and can be used for on-site radioactivity detection and low-level radioactivity measurements.
2019, 36(4): 462-470.
doi: 10.11804/NuclPhysRev.36.04.462
Abstract:
The safety of spent fuel pools in nuclear power plants is a very important safety issue for nuclear power plants, and the performance of neutron absorbing materials is related to the safety of spent fuel pools. The hanging piece of the same kind of neutron absorbing material is placed in the spent fuel pool, and the reliability of the neutron absorbing material in the spent fuel pool can be evaluated by periodically checking the performance of the hanging piece. The development of our B4C_Al alloy coupon testing equipment is expected to play an important role in assessing the safety of spent fuel pools in nuclear power plants. The test equipment firstly establishes a standard curve by using the standard samples with known surface density of 10B, and then the surface density of the sample would be calculated according to the neutron transmittance, thereby reflecting the neutron absorption capacity of the spent fuel pool storage material, and providing a technical means for the safety inspection of reactor spent fuel pools. The equipment is the first boron aluminum alloy coupon testing equipment in China. The development of this equipment lays the experimental foundation for the future non-destructive inspection of domestic boron-containing neutron absorption materials.
The safety of spent fuel pools in nuclear power plants is a very important safety issue for nuclear power plants, and the performance of neutron absorbing materials is related to the safety of spent fuel pools. The hanging piece of the same kind of neutron absorbing material is placed in the spent fuel pool, and the reliability of the neutron absorbing material in the spent fuel pool can be evaluated by periodically checking the performance of the hanging piece. The development of our B4C_Al alloy coupon testing equipment is expected to play an important role in assessing the safety of spent fuel pools in nuclear power plants. The test equipment firstly establishes a standard curve by using the standard samples with known surface density of 10B, and then the surface density of the sample would be calculated according to the neutron transmittance, thereby reflecting the neutron absorption capacity of the spent fuel pool storage material, and providing a technical means for the safety inspection of reactor spent fuel pools. The equipment is the first boron aluminum alloy coupon testing equipment in China. The development of this equipment lays the experimental foundation for the future non-destructive inspection of domestic boron-containing neutron absorption materials.
2019, 36(4): 471-476.
doi: 10.11804/NuclPhysRev.36.04.471
Abstract:
A fission chamber coated with two layers of 238U fissile materials has been developed for the measurements of fast neutrons. The developed fission chamber can operate in the pulse mode, the mean square voltage mode, and the current mode to perform the flux measurement over a large dynamic range. The pulse mode of the fission chamber has been tested with a 252Cf neutron source by measuring the detection efficiency. To evaluate both the mean square voltage mode and the current mode, the pulse amplitudes from the fission chamber in different gas pressures have been measured with the 252Cf source. Then, the pulse amplitudes from the fission chamber have also simulated with the Geant4 Monte Carlo software tool. The simulation can explain measured results, detection efficiency is highest[(4.30±0.7)×10-7] when gas pressure is 2.64×105 Pa and energy spectrum of fission fragments is clearly, so the fission chamber can work in different modes.
A fission chamber coated with two layers of 238U fissile materials has been developed for the measurements of fast neutrons. The developed fission chamber can operate in the pulse mode, the mean square voltage mode, and the current mode to perform the flux measurement over a large dynamic range. The pulse mode of the fission chamber has been tested with a 252Cf neutron source by measuring the detection efficiency. To evaluate both the mean square voltage mode and the current mode, the pulse amplitudes from the fission chamber in different gas pressures have been measured with the 252Cf source. Then, the pulse amplitudes from the fission chamber have also simulated with the Geant4 Monte Carlo software tool. The simulation can explain measured results, detection efficiency is highest[(4.30±0.7)×10-7] when gas pressure is 2.64×105 Pa and energy spectrum of fission fragments is clearly, so the fission chamber can work in different modes.
2019, 36(4): 477-483.
doi: 10.11804/NuclPhysRev.36.04.477
Abstract:
Enhanced low-dose-rate sensitivity (ELDRS), with more degradation occurring at low dose rate for bipolar transistors and integrated circuits (ICs), is considered to be one of the major concerns for total ionizing dose hardness-assurance testing intended for space missions. In this paper, the research progress of ELDRS effect and low dose rate accelerated evaluation technology are reviewed. Combined with the difficult issues of ELDRS effect, the latest research results on ELDRS effect are given. The results from temperature-switching irradiation (TSI) are shown to be conservative with respect to low dose rates irradiation, and the irradiation time can be shorten from 7.7 months to 11 hours. And also the TSI for estimating ELDRS can be applied the SET (Single Event Transients) effect of bipolar circuits with low dose rate irradiation. Similarly, a conservative and rapid evaluation results can be obtained.
Enhanced low-dose-rate sensitivity (ELDRS), with more degradation occurring at low dose rate for bipolar transistors and integrated circuits (ICs), is considered to be one of the major concerns for total ionizing dose hardness-assurance testing intended for space missions. In this paper, the research progress of ELDRS effect and low dose rate accelerated evaluation technology are reviewed. Combined with the difficult issues of ELDRS effect, the latest research results on ELDRS effect are given. The results from temperature-switching irradiation (TSI) are shown to be conservative with respect to low dose rates irradiation, and the irradiation time can be shorten from 7.7 months to 11 hours. And also the TSI for estimating ELDRS can be applied the SET (Single Event Transients) effect of bipolar circuits with low dose rate irradiation. Similarly, a conservative and rapid evaluation results can be obtained.
2019, 36(4): 484-491.
doi: 10.11804/NuclPhysRev.36.04.484
Abstract:
The irradiation resistance capability of structural components in nuclear reactors has a great influence on the system's service life and safety. In this work, the CiADS coupling model between spallation target and subcritical reactor is established by MCNPx2.70, and the atomic dissociation cross sections for CiADS candidate materials are processed by the nuclear data processing software NJOY2016. The irradiation damages for three kinds of stainless steels, 316L, 15-15Ti, SIMP and one kind of ZTA ceramics are calculated and analyzed under three conditions with the number of fuel assemblies of 30, 42 and 72, respectively. When used as CiADS fuel cladding, SIMP steel has the lowest rate of irradiation damage among the three candidate steels. The calculated irradiation damage rate are 1.16, 1.61 and 12.0 dpa/a when the number of fuel assemblies are 30, 42 and 72, respectively. The irradiation damage rate for the fuel cladding made of ZTA materials is much higher than that of the candidate steels. The CiADS center tube suffers the strongest neutron irradiation for the portion near the reaction area between the accelerator beam and the spallation target. The maximum irradiation damage rate is about 2.7 dpa/a for the center tube made of 316L steel when the fuel assemblies are 30.
The irradiation resistance capability of structural components in nuclear reactors has a great influence on the system's service life and safety. In this work, the CiADS coupling model between spallation target and subcritical reactor is established by MCNPx2.70, and the atomic dissociation cross sections for CiADS candidate materials are processed by the nuclear data processing software NJOY2016. The irradiation damages for three kinds of stainless steels, 316L, 15-15Ti, SIMP and one kind of ZTA ceramics are calculated and analyzed under three conditions with the number of fuel assemblies of 30, 42 and 72, respectively. When used as CiADS fuel cladding, SIMP steel has the lowest rate of irradiation damage among the three candidate steels. The calculated irradiation damage rate are 1.16, 1.61 and 12.0 dpa/a when the number of fuel assemblies are 30, 42 and 72, respectively. The irradiation damage rate for the fuel cladding made of ZTA materials is much higher than that of the candidate steels. The CiADS center tube suffers the strongest neutron irradiation for the portion near the reaction area between the accelerator beam and the spallation target. The maximum irradiation damage rate is about 2.7 dpa/a for the center tube made of 316L steel when the fuel assemblies are 30.
2019, 36(4): 492-498.
doi: 10.11804/NuclPhysRev.36.04.492
Abstract:
Gold nanoparticles coated with 11-mercaptoundecanoic acid (mAuNPs) in diameter of 15 mm were synthesized using the ligand exchange method. The synthesized gold nanoparticles mAuNPs were characterized by transmission electron microscopy and Zetasizer. Then, the MTT assay was used to evaluate the toxicity of mAuNPs to mouse melanoma B16-f10 cells. All subsequent irradiation experiments were performed under a carbon ion beam with a linear energy transfer (LET) value of 50 keV/μm. First, coumarin-3-carboxylic acid (3-CCA) was used as a fluorescent probe to detect the radiation enhancement effect of mAuNPs on hydroxyl radicals in aqueous solution. Second, dichlorofluorescein diacetate (DCFH-DA) was used to evaluate the radiation enhancement effect of mAuNPs on intracellular reactive oxygen species (ROS). More importantly, the radiosensitizing effect of mAuNPs on B16-F10 cells under irradiation with carbon ions was assessed with the clonogenic survival assay. Our experimental results showed that mAuNPs had nearly no toxicity to mouse melanoma B16-F10 cells. The yield of hydroxide radicals in ultra-pure water in the presence of mAuNPs after exposure to carbon ions increased by a factor of 1.08~2.95. At a co-culture concentration of 5 μg/mL, mAuNPs increased the level of intracellular ROS and the sensitizer enhancement ratio (SER) of mAuNPs in B16-F10 cells at 10% survival level was 1.15. Thus, our study indicates that mAuNPs have radiation enhancement effect on melanoma cells under heavy ion irradiation.
Gold nanoparticles coated with 11-mercaptoundecanoic acid (mAuNPs) in diameter of 15 mm were synthesized using the ligand exchange method. The synthesized gold nanoparticles mAuNPs were characterized by transmission electron microscopy and Zetasizer. Then, the MTT assay was used to evaluate the toxicity of mAuNPs to mouse melanoma B16-f10 cells. All subsequent irradiation experiments were performed under a carbon ion beam with a linear energy transfer (LET) value of 50 keV/μm. First, coumarin-3-carboxylic acid (3-CCA) was used as a fluorescent probe to detect the radiation enhancement effect of mAuNPs on hydroxyl radicals in aqueous solution. Second, dichlorofluorescein diacetate (DCFH-DA) was used to evaluate the radiation enhancement effect of mAuNPs on intracellular reactive oxygen species (ROS). More importantly, the radiosensitizing effect of mAuNPs on B16-F10 cells under irradiation with carbon ions was assessed with the clonogenic survival assay. Our experimental results showed that mAuNPs had nearly no toxicity to mouse melanoma B16-F10 cells. The yield of hydroxide radicals in ultra-pure water in the presence of mAuNPs after exposure to carbon ions increased by a factor of 1.08~2.95. At a co-culture concentration of 5 μg/mL, mAuNPs increased the level of intracellular ROS and the sensitizer enhancement ratio (SER) of mAuNPs in B16-F10 cells at 10% survival level was 1.15. Thus, our study indicates that mAuNPs have radiation enhancement effect on melanoma cells under heavy ion irradiation.
2019, 36(4): 499-504.
doi: 10.11804/NuclPhysRev.36.04.499
Abstract:
To study the biological effects of 12C6+ ion beams on dry seeds of Artemisia annua L, there are four indicators:survival rate, root length, hypocotyls length, plant height. The results showed that survival rate and root length decreased with increasing doses. While the hypocotyl length first increased and then decreased, the plant height showed a trend of overall decrease, but the plant height increased and decreased at 60 and 90 Gy. After studying the application of M1 generation after irradiation of artemisinin SRAP(sequence related amplified polymorphism) technique, the results showed that the differences between control group and treatment group are embodied at the change of specific bands. All the results indicated that M1 seedings of Artemisia annua L. irradiated by 12C6+ ion has obvious biological effects on both the plant developments and genomic DNA variations.
To study the biological effects of 12C6+ ion beams on dry seeds of Artemisia annua L, there are four indicators:survival rate, root length, hypocotyls length, plant height. The results showed that survival rate and root length decreased with increasing doses. While the hypocotyl length first increased and then decreased, the plant height showed a trend of overall decrease, but the plant height increased and decreased at 60 and 90 Gy. After studying the application of M1 generation after irradiation of artemisinin SRAP(sequence related amplified polymorphism) technique, the results showed that the differences between control group and treatment group are embodied at the change of specific bands. All the results indicated that M1 seedings of Artemisia annua L. irradiated by 12C6+ ion has obvious biological effects on both the plant developments and genomic DNA variations.
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