2014 Vol. 31, No. 4
Display Method:
2014, 31(4): 429-437.
doi: 10.11804/NuclPhysRev.31.04.429
Abstract:
Nuclear symmetry energy characterizing the isospin dependent part of equation of state, is a hot topic in nuclear physics and astrophysics. Although many theoretical and experimental efforts have been performed, due to its difficulty, this problem remains unsolved. There are many approaches to deal with this issue, including nuclear many-body theories, heavy ion reactions, and nuclear giant resonances. Recently,significant progress has been made in constraining the density dependence of the symmetry energy around the saturation density. We explore the symmetry energy around the saturation density with the help of the properties of finite nuclei to reduce the uncertainty as far as possible. It is found that the symmetry energy (coefficient) of 208Pb equals that of nuclear matter at reference density ρA = 0.55ρ0 . This relation links the symmetry energy of the nuclear matter and the one of finite nuclei, with the help of which one can explore the density dependence of the symmetry energy. Thus, the central issue is to obtain the symmetry energy (coefficient) of 208Pb. We exacted it with the experimental −-decay energies of heavy nuclei and with nuclear mass differences, and then to constrain the density dependent symmetry energy at subsaturation density.
Nuclear symmetry energy characterizing the isospin dependent part of equation of state, is a hot topic in nuclear physics and astrophysics. Although many theoretical and experimental efforts have been performed, due to its difficulty, this problem remains unsolved. There are many approaches to deal with this issue, including nuclear many-body theories, heavy ion reactions, and nuclear giant resonances. Recently,significant progress has been made in constraining the density dependence of the symmetry energy around the saturation density. We explore the symmetry energy around the saturation density with the help of the properties of finite nuclei to reduce the uncertainty as far as possible. It is found that the symmetry energy (coefficient) of 208Pb equals that of nuclear matter at reference density ρA = 0.55ρ0 . This relation links the symmetry energy of the nuclear matter and the one of finite nuclei, with the help of which one can explore the density dependence of the symmetry energy. Thus, the central issue is to obtain the symmetry energy (coefficient) of 208Pb. We exacted it with the experimental −-decay energies of heavy nuclei and with nuclear mass differences, and then to constrain the density dependent symmetry energy at subsaturation density.
2014, 31(4): 438-443.
doi: 10.11804/NuclPhysRev.31.04.438
Abstract:
We present a new basis selection algorithm for truncated shell model calculations. In this method the basis is taken as the correlated eigenvectors of the Hamiltonian in each shell-model partition. A truncation scheme is established by naturally taking the low-lying correlated basis vectors in the different partitions, which is equivalent to the j-j coupling scheme of the shell model when all correlated basis vectors are considered. The calculations are compared with standard shell model calculations. The convergence properties of the correlated basis method are also discussed. The calculation results show that one can get both good convergence of energies and wave functions, which indicate the effectiveness of correlated basis shell-model calculation.
We present a new basis selection algorithm for truncated shell model calculations. In this method the basis is taken as the correlated eigenvectors of the Hamiltonian in each shell-model partition. A truncation scheme is established by naturally taking the low-lying correlated basis vectors in the different partitions, which is equivalent to the j-j coupling scheme of the shell model when all correlated basis vectors are considered. The calculations are compared with standard shell model calculations. The convergence properties of the correlated basis method are also discussed. The calculation results show that one can get both good convergence of energies and wave functions, which indicate the effectiveness of correlated basis shell-model calculation.
2014, 31(4): 444-452.
doi: 10.11804/NuclPhysRev.31.04.444
Abstract:
The nuclear reaction rates in the astrophysical environment are indispensable input parameters in different astrophysics theories, and play important roles in understanding the astrophysical nuclear synthesis and the evolution of the universe. However，at the astrophysical temperature, the nuclear reactions proceed at very low energies. Due to the Coulumb barrier the reaction cross sections are very small, so that the direct measurement is almost impossible. The Trojin horse theory provides a useful method to measure indirectly the low energy two body cross sections by measuring the suitable three body reactions. Some approximations are applied in the theory to get convenient formula. This paper introduces the Trojin horse theory and its application in astrophysics nuclear reactions.
The nuclear reaction rates in the astrophysical environment are indispensable input parameters in different astrophysics theories, and play important roles in understanding the astrophysical nuclear synthesis and the evolution of the universe. However，at the astrophysical temperature, the nuclear reactions proceed at very low energies. Due to the Coulumb barrier the reaction cross sections are very small, so that the direct measurement is almost impossible. The Trojin horse theory provides a useful method to measure indirectly the low energy two body cross sections by measuring the suitable three body reactions. Some approximations are applied in the theory to get convenient formula. This paper introduces the Trojin horse theory and its application in astrophysics nuclear reactions.
2014, 31(4): 453-459.
doi: 10.11804/NuclPhysRev.31.04.453
Abstract:
The Primakoff effect is a powerful experimental tool in the nuclear and particle physics, as it has excellent kinematic filters. The future electron-ion collider (EIC) facility has a lot of advantages, such as high center-of-mass energy, high luminosity, broad kinematic range, low background, high particle detection efficiency and various ion species. It will open a door for new era of the Primakoff experiments to test fundamental QCD symmetries, to study the electro-weak properties of hadron and to search for new physics beyond the standard model. The Primakoff experiment is another highlight of the EIC machine.
The Primakoff effect is a powerful experimental tool in the nuclear and particle physics, as it has excellent kinematic filters. The future electron-ion collider (EIC) facility has a lot of advantages, such as high center-of-mass energy, high luminosity, broad kinematic range, low background, high particle detection efficiency and various ion species. It will open a door for new era of the Primakoff experiments to test fundamental QCD symmetries, to study the electro-weak properties of hadron and to search for new physics beyond the standard model. The Primakoff experiment is another highlight of the EIC machine.
2014, 31(4): 460-467.
doi: 10.11804/NuclPhysRev.31.04.460
Abstract:
The charged particles resulting in high energy heavy ion collisions consist of two parts: One is from the hot and dense matter produced in collisions. The other is the leading particles. We suppose that the hot and dense matter expands and freezes out into the charged particles according to the evolution-dominated hydrodynamics, and the leading particles are from participants with approximately the same energy. On the basis of this assumption, we get the pseudorapidity distributions of the charged particles produced in high energy heavy ion collisions, and make a comparison with the experimental data presented by PHOBOS Collaboration at BNL-RHIC in Cu-Cu collisions at (sNN)1/2= 62.4 and 200 GeV. The theoretical predictions are in good accordance with experimental measurements.
The charged particles resulting in high energy heavy ion collisions consist of two parts: One is from the hot and dense matter produced in collisions. The other is the leading particles. We suppose that the hot and dense matter expands and freezes out into the charged particles according to the evolution-dominated hydrodynamics, and the leading particles are from participants with approximately the same energy. On the basis of this assumption, we get the pseudorapidity distributions of the charged particles produced in high energy heavy ion collisions, and make a comparison with the experimental data presented by PHOBOS Collaboration at BNL-RHIC in Cu-Cu collisions at (sNN)1/2= 62.4 and 200 GeV. The theoretical predictions are in good accordance with experimental measurements.
2014, 31(4): 468-474.
doi: 10.11804/NuclPhysRev.31.04.468
Abstract:
High intense muons are required by many applications in muon science. A large acceptance channel for surface muons was designed at China Spallation Neutron Source (CSNS) using a superconducting solenoid and an internal target, which can provide a large solid angle to collect intense surface muons. Compared to conventional separate target and collection system based on quadrupole magnets, a superconducting solenoid with large aperture can collect two orders larger of surface muons. This device was simulated by Geant4 and G4beamline. By analyzing the surface muon production ratio produced by the process that protons bombard four different materials, we chose the graphite as the target material. Then comparing the intensity of surface muon by different angles between the axis of the capture solenoids and the proton beam line, we proposed the capture and transport solenoid system with higher muon production ratio. Finally, the yield of surface muon at the exit of decay solenoid can be up to 108/s.
High intense muons are required by many applications in muon science. A large acceptance channel for surface muons was designed at China Spallation Neutron Source (CSNS) using a superconducting solenoid and an internal target, which can provide a large solid angle to collect intense surface muons. Compared to conventional separate target and collection system based on quadrupole magnets, a superconducting solenoid with large aperture can collect two orders larger of surface muons. This device was simulated by Geant4 and G4beamline. By analyzing the surface muon production ratio produced by the process that protons bombard four different materials, we chose the graphite as the target material. Then comparing the intensity of surface muon by different angles between the axis of the capture solenoids and the proton beam line, we proposed the capture and transport solenoid system with higher muon production ratio. Finally, the yield of surface muon at the exit of decay solenoid can be up to 108/s.
2014, 31(4): 475-781.
doi: 10.11804/NuclPhysRev.31.04.475
Abstract:
High- eld conventional magnets and superconducting magnets for three new projects, which can include Heavy Ion Medical Machine (HIMM), High Intensity heavy ion Accelerator Facility (HIAF), and Accelerator Driven sub-critical System (ADS) project, are under construction or design at Institute of Modern Physics (IMP). In conventional magnet of HIMM, air trim slot and removable pole were used jointly for improving the conventional magnets' quality. The measurements of the magnetic eld distribution in the median plane of the working area have been carried out. Results from Opera-3D simulation show good agreement with the measurement data. For superconducting dipole coil prototype in HIAF Project, which is in design phase, the R&D of cable-around-conduit conductor, 80 K thermal shield , the coil case and a smart coupled mechanical analysis method were described. And for SC solenoid magnet of C-ADS Injector-II, which is in test phase, magnetic eld and strain measurement technology at IMP were introduced during excitation and quench. The present results and methods
may provide some basis experiences on the construction of the magnet at IMP.
High- eld conventional magnets and superconducting magnets for three new projects, which can include Heavy Ion Medical Machine (HIMM), High Intensity heavy ion Accelerator Facility (HIAF), and Accelerator Driven sub-critical System (ADS) project, are under construction or design at Institute of Modern Physics (IMP). In conventional magnet of HIMM, air trim slot and removable pole were used jointly for improving the conventional magnets' quality. The measurements of the magnetic eld distribution in the median plane of the working area have been carried out. Results from Opera-3D simulation show good agreement with the measurement data. For superconducting dipole coil prototype in HIAF Project, which is in design phase, the R&D of cable-around-conduit conductor, 80 K thermal shield , the coil case and a smart coupled mechanical analysis method were described. And for SC solenoid magnet of C-ADS Injector-II, which is in test phase, magnetic eld and strain measurement technology at IMP were introduced during excitation and quench. The present results and methods
may provide some basis experiences on the construction of the magnet at IMP.
2014, 31(4): 482-488.
doi: 10.11804/NuclPhysRev.31.04.482
Abstract:
The βg of cavity in superconducting linac will determine how many cavities and cavity-types will be used in a project, and then it will affect to the total costs. In this paper, to get the most suitable βg of cavity,a linear approximation model has been proposed and a code has been developed combined with the algorithm of the particle swarm optimization(PSO). Then it was been examined in the project of China Accelerator Driven sub-critical System(C-ADS). Finally it was passed and got a set of the most suitableβg and the corresponding physical design. The new design has certain advantages over the existing design for the number of cavity type has been reduced while the total number of cavities was not increased.
The βg of cavity in superconducting linac will determine how many cavities and cavity-types will be used in a project, and then it will affect to the total costs. In this paper, to get the most suitable βg of cavity,a linear approximation model has been proposed and a code has been developed combined with the algorithm of the particle swarm optimization(PSO). Then it was been examined in the project of China Accelerator Driven sub-critical System(C-ADS). Finally it was passed and got a set of the most suitableβg and the corresponding physical design. The new design has certain advantages over the existing design for the number of cavity type has been reduced while the total number of cavities was not increased.
2014, 31(4): 489-493.
doi: 10.11804/NuclPhysRev.31.04.489
Abstract:
The control of the superconducting magnet power supply (SMPS) is very important for Superconducting Electron Cyclotron Resonance Ion source with Advanced design in Lanzhou(SECRAL). In order to improve the safety and the reliability of the SMPS, a remote control system was designed and implemented.There are four power supplies needed to be controlled with suitable strategy to avoid the quench of the superconducting magnet. These four power supplies are used to supply four superconducting solenoids. Because the value and the changing rates of the current for these four solenoids are different, the power supplies must be operated synchronously to keep the current of the solenoids balanced. In this paper, we provide a detailed description for the control strategy of the four power supplies and the architecture of the hardware and the software. A serial switch is used for protocol conversion between TCP/IP and RS232 in firmware. And the software is implemented using VC++. The system can operate the four power supplies automatically after it is triggered. With the help of the control system, operation of the SMPS gets easier and safer.
The control of the superconducting magnet power supply (SMPS) is very important for Superconducting Electron Cyclotron Resonance Ion source with Advanced design in Lanzhou(SECRAL). In order to improve the safety and the reliability of the SMPS, a remote control system was designed and implemented.There are four power supplies needed to be controlled with suitable strategy to avoid the quench of the superconducting magnet. These four power supplies are used to supply four superconducting solenoids. Because the value and the changing rates of the current for these four solenoids are different, the power supplies must be operated synchronously to keep the current of the solenoids balanced. In this paper, we provide a detailed description for the control strategy of the four power supplies and the architecture of the hardware and the software. A serial switch is used for protocol conversion between TCP/IP and RS232 in firmware. And the software is implemented using VC++. The system can operate the four power supplies automatically after it is triggered. With the help of the control system, operation of the SMPS gets easier and safer.
2014, 31(4): 494-498.
doi: 10.11804/NuclPhysRev.31.04.494
Abstract:
The light output response of BC501A liquid scintillator to -rays has been studied. The pulseheightspectra of BC501A (Φ5.08 cm x 5.08 cm) for different PMT high voltages have been measured using 137Cs, 60Co γ-ray sources. The Geant4 simulated pulse-height spectra showed a good agreement with experimental data. The energy resolution functions and energy calibration curves have been obtained by comparing measured light output distribution with simulated one. The position of the Compton edge relative to the position of the maximum and the half height of the spectra has also been studied using Geant4 in detail. The value of Nc/Nmax at the position of Compton edge decreases from 0.8 to 0.7 with the increase of incident -rays energy (0.2~0.3
MeV).
The light output response of BC501A liquid scintillator to -rays has been studied. The pulseheightspectra of BC501A (Φ5.08 cm x 5.08 cm) for different PMT high voltages have been measured using 137Cs, 60Co γ-ray sources. The Geant4 simulated pulse-height spectra showed a good agreement with experimental data. The energy resolution functions and energy calibration curves have been obtained by comparing measured light output distribution with simulated one. The position of the Compton edge relative to the position of the maximum and the half height of the spectra has also been studied using Geant4 in detail. The value of Nc/Nmax at the position of Compton edge decreases from 0.8 to 0.7 with the increase of incident -rays energy (0.2~0.3
MeV).
2014, 31(4): 499-504.
doi: 10.11804/NuclPhysRev.31.04.499
Abstract:
The silicon strip array detector is one of external target facility subsystems in the Cooling Storage Ring on the Heavy Ion Research Facility at Lanzhou (HIRFL-CSR). Using the ASICs, the front-end electronics module has been developed for the silicon strip array detectors and can implement measurement of energy of 96 channels. The performance of the front-end electronics module has been tested. The energy linearity of the front-end electronics module is better than 0.3% for the dynamic range of 0.1 ~ 0.7 V. The energy resolution is better than 0.45%. The maximum channel crosstalk is better than 10%. The channel consistency is better than 1.3%. After continuously working for 24 h at room temperature, the maximum drift of the zero-peak is 1.48 mV.
The silicon strip array detector is one of external target facility subsystems in the Cooling Storage Ring on the Heavy Ion Research Facility at Lanzhou (HIRFL-CSR). Using the ASICs, the front-end electronics module has been developed for the silicon strip array detectors and can implement measurement of energy of 96 channels. The performance of the front-end electronics module has been tested. The energy linearity of the front-end electronics module is better than 0.3% for the dynamic range of 0.1 ~ 0.7 V. The energy resolution is better than 0.45%. The maximum channel crosstalk is better than 10%. The channel consistency is better than 1.3%. After continuously working for 24 h at room temperature, the maximum drift of the zero-peak is 1.48 mV.
2014, 31(4): 505-510.
doi: 10.11804/NuclPhysRev.31.04.505
Abstract:
Monte Carlo simulation is one of the most important numerical simulation methods in nuclear logging. Formation models can be conveniently built with MCNP code, which provides a simple and effective approach for fundamental study of nuclear logging. Monte Carlo method is employed to set up formation models under logging while drilling condition, and the characteristic of azimuthal gamma imaging is simulated. The results present that the azimuthal gamma imaging shows a sinusoidal curve features. The imaging can be used to accurately calculate the relative dip angle of borehole and thickness of radioactive formation. The larger relative dip angle of borehole and the thicker radioactive formation lead to the larger height of the sinusoidal curve in the imaging. The borehole size has no affect for the calculation of the relative dip angle, but largely affects the determination of formation thickness. The standoff of logging tool has great influence for the calculation of the relative dip angle and formation thickness. If the gamma ray counts meet the demand of counting statistics in nuclear logging, the effect of borehole fluid on the imaging can be ignored.
Monte Carlo simulation is one of the most important numerical simulation methods in nuclear logging. Formation models can be conveniently built with MCNP code, which provides a simple and effective approach for fundamental study of nuclear logging. Monte Carlo method is employed to set up formation models under logging while drilling condition, and the characteristic of azimuthal gamma imaging is simulated. The results present that the azimuthal gamma imaging shows a sinusoidal curve features. The imaging can be used to accurately calculate the relative dip angle of borehole and thickness of radioactive formation. The larger relative dip angle of borehole and the thicker radioactive formation lead to the larger height of the sinusoidal curve in the imaging. The borehole size has no affect for the calculation of the relative dip angle, but largely affects the determination of formation thickness. The standoff of logging tool has great influence for the calculation of the relative dip angle and formation thickness. If the gamma ray counts meet the demand of counting statistics in nuclear logging, the effect of borehole fluid on the imaging can be ignored.
2014, 31(4): 511-515.
doi: 10.11804/NuclPhysRev.31.04.511
Abstract:
In order to excite the ions in the Lanzhou Penning Trap (LPT), two sets of RF phase splitters by using the principle of transformer have been developed, one of which is applied for the quadruple excitation and works at a frequency of 200 kHz 4 MHz and the other is for the dipole excitation and works at a frequency of 1700 ~1750 Hz. Their amplitude-frequency and phase-frequency characteristic curves in the condition of without-load and with-load have been tested in detail. The results showed that the amplitudes and the phases
of both RF phase splitters have met their design requirements.
In order to excite the ions in the Lanzhou Penning Trap (LPT), two sets of RF phase splitters by using the principle of transformer have been developed, one of which is applied for the quadruple excitation and works at a frequency of 200 kHz 4 MHz and the other is for the dipole excitation and works at a frequency of 1700 ~1750 Hz. Their amplitude-frequency and phase-frequency characteristic curves in the condition of without-load and with-load have been tested in detail. The results showed that the amplitudes and the phases
of both RF phase splitters have met their design requirements.
2014, 31(4): 516-521.
doi: 10.11804/NuclPhysRev.31.04.516
Abstract:
FinFET presents more advantages than current bulk CMOS technologies, such as high speed, high density, lower power, more functionality and high scalability. A 3D single event effect model of nano-scale FinFET is simulated by using ISE TCAD. The considered physical models include mobility model, quantum effect model, recombination model and radiation effect model. The effects of the doping concentration, gate voltage, ion energy, parasitic capacitor, and technologies nodes on single event transient current in FinFET are analyzed. The possible mechanisms behind these effects are also presented. The results indicate some potential hardened technologies. It includes decreasing source doping concentration, increasing drain and substrate doping concentration, reducing ion energy,upgrading gate voltage (Vg) and optimizing parasitic capacitor.
FinFET presents more advantages than current bulk CMOS technologies, such as high speed, high density, lower power, more functionality and high scalability. A 3D single event effect model of nano-scale FinFET is simulated by using ISE TCAD. The considered physical models include mobility model, quantum effect model, recombination model and radiation effect model. The effects of the doping concentration, gate voltage, ion energy, parasitic capacitor, and technologies nodes on single event transient current in FinFET are analyzed. The possible mechanisms behind these effects are also presented. The results indicate some potential hardened technologies. It includes decreasing source doping concentration, increasing drain and substrate doping concentration, reducing ion energy,upgrading gate voltage (Vg) and optimizing parasitic capacitor.
2014, 31(4): 522-527.
doi: 10.11804/NuclPhysRev.31.04.522
Abstract:
The homogeneity of beam is an important physical parameter in the ground-test accelerator of single event effects (SEEs), it can affect the SEEs evaluation accuracy. Nuclear track detector cannot get the beam profile promptly. A uniformity measurement system based on the Position sensitive parallel plate avalanche detector (PPAC) was built to fulfil the homogeneity analysis in real time during the SEE test. Here its construction and principle, the method of analysis and the result of beam test are described. To validate the result of PPAC, a PET film was synchronously irradiated before the PPAC. In comparison with the obtained results of PET films observation, the uniformity value from the PPAC has an estimated maximum error of 5%.The PPAC has about 1 mm position resolution and 50 mm x 50 mm sensitive area. Which can satisfy the
requirement of uniformity analysis on SEEs test by accelerator irradiation.
The homogeneity of beam is an important physical parameter in the ground-test accelerator of single event effects (SEEs), it can affect the SEEs evaluation accuracy. Nuclear track detector cannot get the beam profile promptly. A uniformity measurement system based on the Position sensitive parallel plate avalanche detector (PPAC) was built to fulfil the homogeneity analysis in real time during the SEE test. Here its construction and principle, the method of analysis and the result of beam test are described. To validate the result of PPAC, a PET film was synchronously irradiated before the PPAC. In comparison with the obtained results of PET films observation, the uniformity value from the PPAC has an estimated maximum error of 5%.The PPAC has about 1 mm position resolution and 50 mm x 50 mm sensitive area. Which can satisfy the
requirement of uniformity analysis on SEEs test by accelerator irradiation.
2014, 31(4): 528-532.
doi: 10.11804/NuclPhysRev.31.04.528
Abstract:
The PET membranes are irradiated by 32S ions. The 32S ions were produced by the HI-13 tandem accelerator in China Institute of Atomic Energy. The membranes used for the experiment have been aged in air for three months. The PET membranes are etched in the particular device. Sodium hydroxide solution is used as etchant. The effects of different concentration of sodium hydroxide solution and etching temperature on the pore shape have been studied. The pores have a diameter of 0.2~ 0.93 μm respectively in different
membranes and the taper angle have been calculated. The pore diameter, etchant concentration and etching temperature respectively as a function of the taper angle under different etching conditions are displayed. The experiment result showed that low concentrations of sodium hydroxide solution with high temperature make the pore taper angle and pore size relatively smaller and the pore more close to a cylinder which enables us to conclude the proper etching condition for producing. Meanwhile, Pore taper angle was relatively minimal on 0.5 mol/L sodium hydroxide solution, at 90 ℃ with etching time in 2 hours.
The PET membranes are irradiated by 32S ions. The 32S ions were produced by the HI-13 tandem accelerator in China Institute of Atomic Energy. The membranes used for the experiment have been aged in air for three months. The PET membranes are etched in the particular device. Sodium hydroxide solution is used as etchant. The effects of different concentration of sodium hydroxide solution and etching temperature on the pore shape have been studied. The pores have a diameter of 0.2~ 0.93 μm respectively in different
membranes and the taper angle have been calculated. The pore diameter, etchant concentration and etching temperature respectively as a function of the taper angle under different etching conditions are displayed. The experiment result showed that low concentrations of sodium hydroxide solution with high temperature make the pore taper angle and pore size relatively smaller and the pore more close to a cylinder which enables us to conclude the proper etching condition for producing. Meanwhile, Pore taper angle was relatively minimal on 0.5 mol/L sodium hydroxide solution, at 90 ℃ with etching time in 2 hours.
2014, 31(4): 533-537.
doi: 10.11804/NuclPhysRev.31.04.533
Abstract:
Heavy ion radiotherapy is a curative treatment for human malignancies and offers hopeful prospects for the treatment of cancer. Recent studies demonstrate that heavy ion irradiation leads to not only cell killing but also genomic instability. Expression of BTG1 inhibits the proliferation of cells and plays important roles in the progress from G0/G1 to S phase in cell cycle. In this study, we found that BTG1 was inducible in human renal cancer 786-O cells in the presence of carbon ion irradiation. Meanwhile, the results of qRT-PCR analyses displayed an inverse relationship between expression of BTG1 and microRNA-19b at different times. The up-regulation of BTG1, which was induced by carbon ion irradiation, was inhibited by microRNA-19b mimic transfected into 786-O cells. Subsequently, down-regulation of BTG1 increased the number of micronuclei in bi-nucleated cell of 786-O cells. Thus, we speculate that microRNA-19b leads to enhancement of heavy ion irradiation induced genomic instability by inhibiting the expression of BTG1 gene.
Heavy ion radiotherapy is a curative treatment for human malignancies and offers hopeful prospects for the treatment of cancer. Recent studies demonstrate that heavy ion irradiation leads to not only cell killing but also genomic instability. Expression of BTG1 inhibits the proliferation of cells and plays important roles in the progress from G0/G1 to S phase in cell cycle. In this study, we found that BTG1 was inducible in human renal cancer 786-O cells in the presence of carbon ion irradiation. Meanwhile, the results of qRT-PCR analyses displayed an inverse relationship between expression of BTG1 and microRNA-19b at different times. The up-regulation of BTG1, which was induced by carbon ion irradiation, was inhibited by microRNA-19b mimic transfected into 786-O cells. Subsequently, down-regulation of BTG1 increased the number of micronuclei in bi-nucleated cell of 786-O cells. Thus, we speculate that microRNA-19b leads to enhancement of heavy ion irradiation induced genomic instability by inhibiting the expression of BTG1 gene.
2014, 31(4): 538-542.
doi: 10.11804/NuclPhysRev.31.04.538
Abstract:
Transmissions of 300 and 600 keV O7+ ions through a single glass macrocapillary were investigated.The transmitted fraction and the deflection angle for various tilt angles were measured using the Distribution Sensitive Faraday Cup. The results show the incomplete guiding that the deflection angle is not equal to the tilt angle. The incomplete guiding results from that the potential established by the deposited charge is not strong enough in contrast to the high transverse velocity of the ions and it leads to the ions deviating from the capillary axis exiting out. The higher incident energy, the weaker guiding effect.
Transmissions of 300 and 600 keV O7+ ions through a single glass macrocapillary were investigated.The transmitted fraction and the deflection angle for various tilt angles were measured using the Distribution Sensitive Faraday Cup. The results show the incomplete guiding that the deflection angle is not equal to the tilt angle. The incomplete guiding results from that the potential established by the deposited charge is not strong enough in contrast to the high transverse velocity of the ions and it leads to the ions deviating from the capillary axis exiting out. The higher incident energy, the weaker guiding effect.
2014, 31(4): 542-549.
doi: 10.11804/NuclPhysRev.31.04.542
Abstract:
Radial and axial fuel shuffling Traveling Wave Reactor (TWR)core were designed in detail, and burn-up calculation code MCORE was used to perform calculation and analysis. For the axial core, stable nuclide densities and power distribution were obtained, and the breeding-burning wave was simulated. For steady state, keff is 1.065, the drift speed is about 5.0 cm/a, and the burn-up is up to 400.0 MWD/kg-HM. For the 8 adial core, the fuel is shuffled from outside in, and the power distribution becomes stable after several shuffling steps. The results show that, asymptotic keff parabolically varies with the shuffling period, while the burn-up increases linearly with the shuffling period. To reduce the power peak, shuffling period 450 d is recognized as the best design. Asymptotic keff is 1.020, and the average burn-up is up to 156.0 MWD/kg-HM.
Radial and axial fuel shuffling Traveling Wave Reactor (TWR)core were designed in detail, and burn-up calculation code MCORE was used to perform calculation and analysis. For the axial core, stable nuclide densities and power distribution were obtained, and the breeding-burning wave was simulated. For steady state, keff is 1.065, the drift speed is about 5.0 cm/a, and the burn-up is up to 400.0 MWD/kg-HM. For the 8 adial core, the fuel is shuffled from outside in, and the power distribution becomes stable after several shuffling steps. The results show that, asymptotic keff parabolically varies with the shuffling period, while the burn-up increases linearly with the shuffling period. To reduce the power peak, shuffling period 450 d is recognized as the best design. Asymptotic keff is 1.020, and the average burn-up is up to 156.0 MWD/kg-HM.
2014, 31(4): 550-554.
doi: 10.11804/NuclPhysRev.31.04.550
Abstract:
We use Geant4 toolkit to model high-energy proton irradiating spallation target in an Accelerator-Driven sub-critical System (ADS). The simulated neutron leakage spectrum resulting from proton bombarding liquid metal targets of lead, lead-bismuth eutectic, and hydrargyrum are obtained. The neutron leakage yields from lead target and their axial integrated distributions are calculated with different incident proton energies.Considering the incident proton efficiency and the whole size and mass of the reactor core, the optimized target radius and target height are suggested to be a range of 16~ 24 cm and 100 cm, respectively, which is helpful for the physical and engineering design of the ADS spallation target.
We use Geant4 toolkit to model high-energy proton irradiating spallation target in an Accelerator-Driven sub-critical System (ADS). The simulated neutron leakage spectrum resulting from proton bombarding liquid metal targets of lead, lead-bismuth eutectic, and hydrargyrum are obtained. The neutron leakage yields from lead target and their axial integrated distributions are calculated with different incident proton energies.Considering the incident proton efficiency and the whole size and mass of the reactor core, the optimized target radius and target height are suggested to be a range of 16~ 24 cm and 100 cm, respectively, which is helpful for the physical and engineering design of the ADS spallation target.
2014, 31(4): 555-560.
doi: 10.11804/NuclPhysRev.31.04.555
Abstract:
Burnup analysis plays an important role in the design of ADS since subcritical reactor has complex geometry structure as well as anisotropic ux distribution caused by external source. In order to simulate burnup, a Monte-Carlo Activation and Depletion Code System (MCADS) has been developed combining advantages of MCNP in complex geometry neutron transport calculation with LITAC in fast and precise inventory calculation. Then, IAEA ADS-Benchmark (stage1) is worked out, verifying that the code can be used to deal with subcritical reactor with an external source. Also, burnup, source evolution, void reactivity, initial spatial power density distribution are gured out with the code, showing good agreement with results from other countries.
Burnup analysis plays an important role in the design of ADS since subcritical reactor has complex geometry structure as well as anisotropic ux distribution caused by external source. In order to simulate burnup, a Monte-Carlo Activation and Depletion Code System (MCADS) has been developed combining advantages of MCNP in complex geometry neutron transport calculation with LITAC in fast and precise inventory calculation. Then, IAEA ADS-Benchmark (stage1) is worked out, verifying that the code can be used to deal with subcritical reactor with an external source. Also, burnup, source evolution, void reactivity, initial spatial power density distribution are gured out with the code, showing good agreement with results from other countries.
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