2019 Vol. 36, No. 1
Display Method:
2019, 36(1): 1-36.
doi: 10.11804/NuclPhysRev.36.01.001
Abstract:
The matter state inside neutron stars (NSs) is an exciting problem in nuclear physics, particle physics and astrophysics. The equation of state (EOS) of NSs plays a crucial role in the present multimessenger astronomy, especially after the event of GW170817. Thanks to accruing studies with advanced telescopes and radioactive beam facilities, the unknown EOS of supranuclear matter could soon be understood. We review the current status of the EOS for pulsar-like compact objects, that have been studied with both microscopic many-body approaches and phenomenological models. The appearance of strange baryonic matter and strange quark matter are also discussed. We compare the theoretical predictions with different data coming from both nuclear physics experiments and astrophysical observations. Despite great progresses obtained in dense nuclear matter properties, there are various challenges ahead, such as the model dependence of the constraints extracted from either experimental or observational data, the lack of a consistent and rigorous many-body treatment of all parts of the star, the dependence of many observables on the turbulent dynamics of relevant hot dense system. As LIGO is about to run again and discover more NS merger events, multimessenger observations are expected to finally unravel the mystery of NS structure.
The matter state inside neutron stars (NSs) is an exciting problem in nuclear physics, particle physics and astrophysics. The equation of state (EOS) of NSs plays a crucial role in the present multimessenger astronomy, especially after the event of GW170817. Thanks to accruing studies with advanced telescopes and radioactive beam facilities, the unknown EOS of supranuclear matter could soon be understood. We review the current status of the EOS for pulsar-like compact objects, that have been studied with both microscopic many-body approaches and phenomenological models. The appearance of strange baryonic matter and strange quark matter are also discussed. We compare the theoretical predictions with different data coming from both nuclear physics experiments and astrophysical observations. Despite great progresses obtained in dense nuclear matter properties, there are various challenges ahead, such as the model dependence of the constraints extracted from either experimental or observational data, the lack of a consistent and rigorous many-body treatment of all parts of the star, the dependence of many observables on the turbulent dynamics of relevant hot dense system. As LIGO is about to run again and discover more NS merger events, multimessenger observations are expected to finally unravel the mystery of NS structure.
2019, 36(1): 37-42.
doi: 10.11804/NuclPhysRev.36.01.037
Abstract:
The 14O(α, p)17F reaction is one of the important breakout reactions in type I X-ray burst. This work reported a new cross section measurement of its reverse reaction of 1H(17F,α)14O. The experiment was performed using the CNS radioactive ion beam separator (CRIB), located at the Center for Nuclear Study (CNS), the University of Tokyo. The sequent background measurement was carried out at Radioactive Beam Line in Lanzhou (RIBLL1). 17F beam was produced via the transfer reaction of 2H(16O, n)17F, subsequently separated and purified by CRIB and bombarded a thick hydrogen H2 gas target. The recoiling α particles were measured by three △E-E silicon telescopes at three different angles. The total cross sections of 1H(17F,α)14O have been derived at Ec.m.=2.7~3.4 MeV based on an isotropic angular distribution assumption. Our results are consistent with the previous ones in the energy region of Ec.m.>3 MeV, and we also obtained some new data in the low energy region, which partly support the destructive interference between the direct and resonant reaction mechanism predicted by the theory.
The 14O(α, p)17F reaction is one of the important breakout reactions in type I X-ray burst. This work reported a new cross section measurement of its reverse reaction of 1H(17F,α)14O. The experiment was performed using the CNS radioactive ion beam separator (CRIB), located at the Center for Nuclear Study (CNS), the University of Tokyo. The sequent background measurement was carried out at Radioactive Beam Line in Lanzhou (RIBLL1). 17F beam was produced via the transfer reaction of 2H(16O, n)17F, subsequently separated and purified by CRIB and bombarded a thick hydrogen H2 gas target. The recoiling α particles were measured by three △E-E silicon telescopes at three different angles. The total cross sections of 1H(17F,α)14O have been derived at Ec.m.=2.7~3.4 MeV based on an isotropic angular distribution assumption. Our results are consistent with the previous ones in the energy region of Ec.m.>3 MeV, and we also obtained some new data in the low energy region, which partly support the destructive interference between the direct and resonant reaction mechanism predicted by the theory.
2019, 36(1): 43-48.
doi: 10.11804/NuclPhysRev.36.01.043
Abstract:
Ground-state shape (phase) crossover in Er and Yb isotopes is manifested in the axially deformed Nilsson mean-field plus extended pairing model. The energy ratio R02+/21+, the odd-even mass differences and the information entropy are calculated under the present model, reproduce the shape (phase) crossover behaviors of these quantities in 155-163Er and 157-165Yb isotopes. From the analysis of these quantities as functions of the quadrupole deformation parameter and the overall pairing interaction strength, it is shown that the crossover is mainly driven by the competition between the pairing interaction and the quadrupole deformation, which thus provides the origin of the shape (phase) crossover in the present model.
Ground-state shape (phase) crossover in Er and Yb isotopes is manifested in the axially deformed Nilsson mean-field plus extended pairing model. The energy ratio R02+/21+, the odd-even mass differences and the information entropy are calculated under the present model, reproduce the shape (phase) crossover behaviors of these quantities in 155-163Er and 157-165Yb isotopes. From the analysis of these quantities as functions of the quadrupole deformation parameter and the overall pairing interaction strength, it is shown that the crossover is mainly driven by the competition between the pairing interaction and the quadrupole deformation, which thus provides the origin of the shape (phase) crossover in the present model.
2019, 36(1): 49-54.
doi: 10.11804/NuclPhysRev.36.01.049
Abstract:
During heavy ion accelerator operation, the charge exchange effect between ions and residual gas molecules is the key factor to influence beam lifetime. The charge exchange process has ions lost on the wall and leads to a dynamical vacuum change, which will seriously affect the accelerator operation and reduce the extraction beam intensity. The Institute of Modern Physics' future project, called High Intensity heavy ion Accelerator Facility (HIAF), will be built in Huizhou city, Guangdong Province, China. The Booster Ring (BRing) will provide 2×11 ppp 238U35+ for nuclear physics experiments. This article studies the track of particle U36+ before impacting on the wall, which is the reference particle U35+ losing one electron, and gets the U36+ loss distribution along the BRing. The simulation result shows that U36+ will be influenced seriously by dispersion elements, and will be lost in the drift sections after the dipoles. Collimators made out of materials with low desorption will be installed in the particles lost positions. The collimator efficiency after optimization can be larger than 95%. It also shows BRing average pressure change and beam intensity change between collimators on and off. The result points out that the BRing average pressure change will be less than 10% with collimators on, which makes BRing operate stably.
During heavy ion accelerator operation, the charge exchange effect between ions and residual gas molecules is the key factor to influence beam lifetime. The charge exchange process has ions lost on the wall and leads to a dynamical vacuum change, which will seriously affect the accelerator operation and reduce the extraction beam intensity. The Institute of Modern Physics' future project, called High Intensity heavy ion Accelerator Facility (HIAF), will be built in Huizhou city, Guangdong Province, China. The Booster Ring (BRing) will provide 2×11 ppp 238U35+ for nuclear physics experiments. This article studies the track of particle U36+ before impacting on the wall, which is the reference particle U35+ losing one electron, and gets the U36+ loss distribution along the BRing. The simulation result shows that U36+ will be influenced seriously by dispersion elements, and will be lost in the drift sections after the dipoles. Collimators made out of materials with low desorption will be installed in the particles lost positions. The collimator efficiency after optimization can be larger than 95%. It also shows BRing average pressure change and beam intensity change between collimators on and off. The result points out that the BRing average pressure change will be less than 10% with collimators on, which makes BRing operate stably.
2019, 36(1): 55-61.
doi: 10.11804/NuclPhysRev.36.01.055
Abstract:
Heavy ion therapy is the most advanced and effective method of radiotherapy. Because it has the advantage that it has minimal damage to surrounding healthy tissue and the greatest cancer celling killing effect. The relationship between heavy ion Bragg peak and beam energy requires the accelerator to switch the beam between different energy. The PXI RF control system plays an important role in Heavy Ion Medical Machine(HIMM). It can automatically change the waveform files according to the optical event. The system is mainly consisted by three FPGA cards, based on PXI bus, and mainly use the technology such as SOPC, DSP and so on. The PXI RF control system for HIMM has been tested through a long-term stability experiments, the system meets the proposed requirements.
Heavy ion therapy is the most advanced and effective method of radiotherapy. Because it has the advantage that it has minimal damage to surrounding healthy tissue and the greatest cancer celling killing effect. The relationship between heavy ion Bragg peak and beam energy requires the accelerator to switch the beam between different energy. The PXI RF control system plays an important role in Heavy Ion Medical Machine(HIMM). It can automatically change the waveform files according to the optical event. The system is mainly consisted by three FPGA cards, based on PXI bus, and mainly use the technology such as SOPC, DSP and so on. The PXI RF control system for HIMM has been tested through a long-term stability experiments, the system meets the proposed requirements.
2019, 36(1): 62-70.
doi: 10.11804/NuclPhysRev.36.01.062
Abstract:
The accelerator driven subcritical system (ADS) has put forward unprecedented demands on the stability and beam trip of the accelerator operation. Depending on analysis, failure of the superconducting cavities is a major cause for beam trip of the superconducting cavity. Therefore, a new method of piecewise compensation is proposed to improve the stability of high power superconductivity linac. The piecewise compensation scheme proposed in this paper is compared with the existing global compensation and local compensation technology. While guaranteeing the beam quality of the accelerator and without beam loss transmission, the piecewise compensation method can optimize the number of superconducting cavities involved in energy compensation and reduce the demand for the backup redundancy of power sources of the superconducting cavities. At the end of the paper, the multi-particle simulation of piecewise compensation aims at the physical design of CiADS superconducting linac. The result shows that 48% of superconducting cavities modify the cavity's Epeak during the compensation process and the demanded redundancy of total power sources is less than 20% under the premise of successful compensation for the failure of superconducting cavities through the piecewise compensation method.
The accelerator driven subcritical system (ADS) has put forward unprecedented demands on the stability and beam trip of the accelerator operation. Depending on analysis, failure of the superconducting cavities is a major cause for beam trip of the superconducting cavity. Therefore, a new method of piecewise compensation is proposed to improve the stability of high power superconductivity linac. The piecewise compensation scheme proposed in this paper is compared with the existing global compensation and local compensation technology. While guaranteeing the beam quality of the accelerator and without beam loss transmission, the piecewise compensation method can optimize the number of superconducting cavities involved in energy compensation and reduce the demand for the backup redundancy of power sources of the superconducting cavities. At the end of the paper, the multi-particle simulation of piecewise compensation aims at the physical design of CiADS superconducting linac. The result shows that 48% of superconducting cavities modify the cavity's Epeak during the compensation process and the demanded redundancy of total power sources is less than 20% under the premise of successful compensation for the failure of superconducting cavities through the piecewise compensation method.
2019, 36(1): 71-77.
doi: 10.11804/NuclPhysRev.36.01.071
Abstract:
As the development of high flux neutron sources and neutron scattering spectrometers in China, more and more neutron detectors with high detection efficiency, high position resolution, high time resolution and low gamma sensitivity are need ungently. 3He based neutron detector is one of the best options. Recently, because of the 3He gas shortage and its expensive price, we must find a new replacement of 3He. A two-dimensional position sensitive neutron detector based on multi-layer Multi Wires Proportional Chambers (mMWPC) with 10B4C converter was proposed in this paper. The neutron detection efficiency, position resolution and γ compression were simulated with Geant4 and Garfield++. The results show that with 40 layers of neutron convertor, high themal neutron (E=0.025 eV) detection of~54%, best position resolution of 2.6 mm (FWHM) and high n/γ rejection ratio of~107 with the threshold of 200 keV can be achieved, which can meet the requirements of most spectrometers. This simulation results lay a good foundation for the next step of detector construction and test.
As the development of high flux neutron sources and neutron scattering spectrometers in China, more and more neutron detectors with high detection efficiency, high position resolution, high time resolution and low gamma sensitivity are need ungently. 3He based neutron detector is one of the best options. Recently, because of the 3He gas shortage and its expensive price, we must find a new replacement of 3He. A two-dimensional position sensitive neutron detector based on multi-layer Multi Wires Proportional Chambers (mMWPC) with 10B4C converter was proposed in this paper. The neutron detection efficiency, position resolution and γ compression were simulated with Geant4 and Garfield++. The results show that with 40 layers of neutron convertor, high themal neutron (E=0.025 eV) detection of~54%, best position resolution of 2.6 mm (FWHM) and high n/γ rejection ratio of~107 with the threshold of 200 keV can be achieved, which can meet the requirements of most spectrometers. This simulation results lay a good foundation for the next step of detector construction and test.
2019, 36(1): 78-84.
doi: 10.11804/NuclPhysRev.36.01.078
Abstract:
Scintillator detectors are widely used in modern nuclear and particle physics experiments. Studying the light attenuation of scintillator detector (LASD) is vitally important for extracting proper measurements of energy and time. In this paper, we integrate the isotropic fluorescence over solid angle to study the influence on overall light-intensity from varying optical path at different angle. Based on numerical results, a universal formula for describing LASD is derived. Under certain condition, our formula can be written as a form of widely-used double-exponential function. The universal formula describes the experimental data of PSD at DAMPE, reducing the maximum deviation at far-side of the scintillator from~10% to less than 2%. Moreover, our model also deciphers Kaiser's experiment, Gierlik's experiment and Platino's experiment successfully.
Scintillator detectors are widely used in modern nuclear and particle physics experiments. Studying the light attenuation of scintillator detector (LASD) is vitally important for extracting proper measurements of energy and time. In this paper, we integrate the isotropic fluorescence over solid angle to study the influence on overall light-intensity from varying optical path at different angle. Based on numerical results, a universal formula for describing LASD is derived. Under certain condition, our formula can be written as a form of widely-used double-exponential function. The universal formula describes the experimental data of PSD at DAMPE, reducing the maximum deviation at far-side of the scintillator from~10% to less than 2%. Moreover, our model also deciphers Kaiser's experiment, Gierlik's experiment and Platino's experiment successfully.
2019, 36(1): 85-90.
doi: 10.11804/NuclPhysRev.36.01.085
Abstract:
Compared to THGEM (Thick Gas Electron Multiplier), the novel Multilayer Thick Gaseous Electron Multiplier (M-THGEM) has many advantages, such as continuous avalanche zone, more compact structure, high gain at low pressure and low operating voltage, and easy to make large-area production. In the presented work, two types of the M-THGEM detector (two or three layers) were modeled, and their main principle and performances were also studied by simulation. Two types of the detector were molded and simulated by using the finite element software (ANSYS), and the electric field distribution and nodes information lists were figured out. The effective gain and induced signal from M-THGEM detector at different gas pressures and operating voltages were studied with the Garfield++ package. The simulation results shown that M-THGEM can obtain a stable higher gain around 105 in an environment where has a low pressure even in 200 Torr and within a pure inertia gas such as He. At this condition, the width of the induced signal from the three-layers structure is around 120 ns. Additionally, an asymmetric way of the applied voltage was studied and aim to reduce the efficiency of ion feedback, and our results show that this method is effective.
Compared to THGEM (Thick Gas Electron Multiplier), the novel Multilayer Thick Gaseous Electron Multiplier (M-THGEM) has many advantages, such as continuous avalanche zone, more compact structure, high gain at low pressure and low operating voltage, and easy to make large-area production. In the presented work, two types of the M-THGEM detector (two or three layers) were modeled, and their main principle and performances were also studied by simulation. Two types of the detector were molded and simulated by using the finite element software (ANSYS), and the electric field distribution and nodes information lists were figured out. The effective gain and induced signal from M-THGEM detector at different gas pressures and operating voltages were studied with the Garfield++ package. The simulation results shown that M-THGEM can obtain a stable higher gain around 105 in an environment where has a low pressure even in 200 Torr and within a pure inertia gas such as He. At this condition, the width of the induced signal from the three-layers structure is around 120 ns. Additionally, an asymmetric way of the applied voltage was studied and aim to reduce the efficiency of ion feedback, and our results show that this method is effective.
2019, 36(1): 91-95.
doi: 10.11804/NuclPhysRev.36.01.091
Abstract:
Metal nanowires, as one of the most crucial components of nanoelectronic devices in the future, have attracted enormous attention. Therefore, it is of great significance to investigate the electrical properties of single metal nanowires. Herein, the single Cu nanowire with diameter of 64 nm was successfully prepared by using single-ion track template method combined with electrochemical deposition approach, and its I-V curve was measured. Such a diameter represents the thinnest one as comparing the reported ones obtained by the same method. The results illustrated that the process of formation and growth, as well as the final diameter of single nanochannel in template can be monitored and measured by conductance method. During the electrochemical deposition, the dynamic evolution of the deposition of nanowire can be clearly reflected through the deposition current and deposition time. At the same time, I-V measurements reveal that the Cu nanowire has typical metallic characteristic. For the first time, the resistivity of such a thin nanowire is obtained and its resistivity is 3.46 μΩ·cm which is around twice that of Cu bulk materials. The increase of resistivity is believed coming from finite size effects and may be related to the electrons scattering at the grain boundaries and surfaces.
Metal nanowires, as one of the most crucial components of nanoelectronic devices in the future, have attracted enormous attention. Therefore, it is of great significance to investigate the electrical properties of single metal nanowires. Herein, the single Cu nanowire with diameter of 64 nm was successfully prepared by using single-ion track template method combined with electrochemical deposition approach, and its I-V curve was measured. Such a diameter represents the thinnest one as comparing the reported ones obtained by the same method. The results illustrated that the process of formation and growth, as well as the final diameter of single nanochannel in template can be monitored and measured by conductance method. During the electrochemical deposition, the dynamic evolution of the deposition of nanowire can be clearly reflected through the deposition current and deposition time. At the same time, I-V measurements reveal that the Cu nanowire has typical metallic characteristic. For the first time, the resistivity of such a thin nanowire is obtained and its resistivity is 3.46 μΩ·cm which is around twice that of Cu bulk materials. The increase of resistivity is believed coming from finite size effects and may be related to the electrons scattering at the grain boundaries and surfaces.
2019, 36(1): 96-103.
doi: 10.11804/NuclPhysRev.36.01.096
Abstract:
This paper describes the development of a fast robust optimization tool that takes advantage of the GPU technologies. The objective function of the robust optimization model considered nine boundary dose distributions——two for ±range uncertainties, six for ±set-up uncertainties along anteroposterior (A-P), lateral (R-L) and superior{inferior (S-I) directions, and one for nominal situation. The nine boundary influence matrices were calculated using an in-house dose engine for proton pencil beams of a finite size, while the conjugate gradient method was applied to minimize the objective function. The GPU platform was adopted to accelerate both the proton dose calculation algorithm and the conjugate gradient method. Three clinical cases-one head and neck cancer case, one lung cancer case and one prostate cancer case-were investigated to demonstrate the clinical significance of the proposed robust optimizer. Compared with conventional planning target volume (PTV) based IMPT plans, the proposed method was found to be conducive in designing robust treatment plans that were less sensitive to range and setup uncertainties. The three cases showed that targets could achieve high dose uniformity while organs at risks (OARs) were under better protection against setup and range errors. The run times for the three cases were around 10 s for 100 iterations. The GPU-based fast robust optimizer developed in this study can serve to improve the reliability of traditional proton treatment planning by achieving a high level of robustness in a much shorter time.
This paper describes the development of a fast robust optimization tool that takes advantage of the GPU technologies. The objective function of the robust optimization model considered nine boundary dose distributions——two for ±range uncertainties, six for ±set-up uncertainties along anteroposterior (A-P), lateral (R-L) and superior{inferior (S-I) directions, and one for nominal situation. The nine boundary influence matrices were calculated using an in-house dose engine for proton pencil beams of a finite size, while the conjugate gradient method was applied to minimize the objective function. The GPU platform was adopted to accelerate both the proton dose calculation algorithm and the conjugate gradient method. Three clinical cases-one head and neck cancer case, one lung cancer case and one prostate cancer case-were investigated to demonstrate the clinical significance of the proposed robust optimizer. Compared with conventional planning target volume (PTV) based IMPT plans, the proposed method was found to be conducive in designing robust treatment plans that were less sensitive to range and setup uncertainties. The three cases showed that targets could achieve high dose uniformity while organs at risks (OARs) were under better protection against setup and range errors. The run times for the three cases were around 10 s for 100 iterations. The GPU-based fast robust optimizer developed in this study can serve to improve the reliability of traditional proton treatment planning by achieving a high level of robustness in a much shorter time.
2019, 36(1): 104-110.
doi: 10.11804/NuclPhysRev.36.01.104
Abstract:
The radiosensitizing effect of Honokiol (HNK) on non-small cell lung carcinoma (NSCLC) cell lines A549 and H1299 to low-linear energy transfer (LET) X-rays and high-LET carbon ions was investigated in this study. First, the inhibitory effects of HNK on the growth of A549 and H1299 cells were detected by CCK-8 assay, and 20 μmol/L HNK treatment was found to induce a growth inhibitory effect slightly in these two cell lines. Cells were pre-treated with HNK and then irradiated with X-rays and carbon ions of different doses. Cellular radiosensitivity, apoptosis and DNA damage were analyzed by clonogenic survival, Annexin-PI staining and γH2AX foci, respectively. The results showed the cells were more sensitive to carbon ion irradiation compared to X-rays and the radiosensitization of HNK was only observed after carbon ion irradiation. Furthermore, the co-treatment led to higher apoptosis rate 48 h after irradiation and increased the positive rate of γH2AX foci 24 h after irradiation in A549 and H1299 cells compared with those in the groups treated with carbon ion irradiation alone. These phenomena were not observed after X-ray irradiation. Our data suggest that the pre-treatment with HNK inhibited DNA DSB repair, induced apoptosis and then enhanced the cellular radiosensitivity to carbon ions in NSCLC cells.
The radiosensitizing effect of Honokiol (HNK) on non-small cell lung carcinoma (NSCLC) cell lines A549 and H1299 to low-linear energy transfer (LET) X-rays and high-LET carbon ions was investigated in this study. First, the inhibitory effects of HNK on the growth of A549 and H1299 cells were detected by CCK-8 assay, and 20 μmol/L HNK treatment was found to induce a growth inhibitory effect slightly in these two cell lines. Cells were pre-treated with HNK and then irradiated with X-rays and carbon ions of different doses. Cellular radiosensitivity, apoptosis and DNA damage were analyzed by clonogenic survival, Annexin-PI staining and γH2AX foci, respectively. The results showed the cells were more sensitive to carbon ion irradiation compared to X-rays and the radiosensitization of HNK was only observed after carbon ion irradiation. Furthermore, the co-treatment led to higher apoptosis rate 48 h after irradiation and increased the positive rate of γH2AX foci 24 h after irradiation in A549 and H1299 cells compared with those in the groups treated with carbon ion irradiation alone. These phenomena were not observed after X-ray irradiation. Our data suggest that the pre-treatment with HNK inhibited DNA DSB repair, induced apoptosis and then enhanced the cellular radiosensitivity to carbon ions in NSCLC cells.
2019, 36(1): 111-117.
doi: 10.11804/NuclPhysRev.36.01.111
Abstract:
Transition energies and rates of K, L, and M X-ray lines from electric-dipole transition of americium have been calculated using GRASP2K code based on the Dirac-Hartee-Fock method. The effects of the Breit interaction, vacuum polarization and self energy were taken into account. It is found that the present results agree within 0.04% with other experimental and theoretical values. Furthermore, we also calculated transition energies and rates of the K-, L-, and M-shell hole states of americium ions with charge states Am1+-Am6+ for the first time. It is found that the transition energies and rates change slightly relative to the corresponding results of americium atoms, which indicates that the outermost electrons can hardly affect inner-shell transition properties.
Transition energies and rates of K, L, and M X-ray lines from electric-dipole transition of americium have been calculated using GRASP2K code based on the Dirac-Hartee-Fock method. The effects of the Breit interaction, vacuum polarization and self energy were taken into account. It is found that the present results agree within 0.04% with other experimental and theoretical values. Furthermore, we also calculated transition energies and rates of the K-, L-, and M-shell hole states of americium ions with charge states Am1+-Am6+ for the first time. It is found that the transition energies and rates change slightly relative to the corresponding results of americium atoms, which indicates that the outermost electrons can hardly affect inner-shell transition properties.
2019, 36(1): 118-123.
doi: 10.11804/NuclPhysRev.36.01.118
Abstract:
Neutron spectra produced through spallation reaction are key parameters in the design of Accelerator Driven Subcritical Systems. Since the energy span is large and reaction channels are complicated, no complete evaluated nuclear data library is ready for use. Suitable theoretical models are required to calculate the data. The CiADS (China initiative Accelerator Driven System) is going to be constructed in China. At the first stage, the adopted proton energy is about 250 MeV. FLUKA and GEANT4 are used to calculate the double differential cross sections at 7.5°, 30°, 60° and 150° induced by 256 MeV protons bombarding on thin aluminum, iron, lead and uranium targets, respectively. The double differential neutron yields at 30°, 60°, 120° and 150° are also calculated for 256 MeV protons bombarding on thick aluminum, iron and uranium targets, respectively. Three model lists INCLXX_HP, BIC_HP and BERT_HP implemented in GEANT4 are used separately. The calculation results are compared with corresponding experimental data. It is shown that results calculated with FLUKA and INCLXX_HP in GEANT4 fit the corresponding experimental data much better. The calculation results with BIC_HP overestimate the experimental data for thin targets in 5~30 MeV for more than 100%, except for aluminum at 150° and lead at 30°. For uranium target, the results calculated with BIC_HP is greater than the experimental results by more than 70% in the energy range 5~30 MeV at 30° and 60° and by more than 100% in the energy range above 5 MeV at 120° and 150°. In 20~100 MeV for aluminum, iron and lead targets, calculation results at 7.5° and 30° with BERT_HP underestimate the experimental data by more than 40%. And for uranium target, the experimental data up to 20 MeV are overestimated by more than 100%.
Neutron spectra produced through spallation reaction are key parameters in the design of Accelerator Driven Subcritical Systems. Since the energy span is large and reaction channels are complicated, no complete evaluated nuclear data library is ready for use. Suitable theoretical models are required to calculate the data. The CiADS (China initiative Accelerator Driven System) is going to be constructed in China. At the first stage, the adopted proton energy is about 250 MeV. FLUKA and GEANT4 are used to calculate the double differential cross sections at 7.5°, 30°, 60° and 150° induced by 256 MeV protons bombarding on thin aluminum, iron, lead and uranium targets, respectively. The double differential neutron yields at 30°, 60°, 120° and 150° are also calculated for 256 MeV protons bombarding on thick aluminum, iron and uranium targets, respectively. Three model lists INCLXX_HP, BIC_HP and BERT_HP implemented in GEANT4 are used separately. The calculation results are compared with corresponding experimental data. It is shown that results calculated with FLUKA and INCLXX_HP in GEANT4 fit the corresponding experimental data much better. The calculation results with BIC_HP overestimate the experimental data for thin targets in 5~30 MeV for more than 100%, except for aluminum at 150° and lead at 30°. For uranium target, the results calculated with BIC_HP is greater than the experimental results by more than 70% in the energy range 5~30 MeV at 30° and 60° and by more than 100% in the energy range above 5 MeV at 120° and 150°. In 20~100 MeV for aluminum, iron and lead targets, calculation results at 7.5° and 30° with BERT_HP underestimate the experimental data by more than 40%. And for uranium target, the experimental data up to 20 MeV are overestimated by more than 100%.
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