2022 Vol. 39, No. 1
Display Method:
2022, 39(1): 1-15.
doi: 10.11804/NuclPhysRev.39.2021075
Abstract:
Within the framework of Lanzhou quantum molecular dynamics(LQMD) transport model, the isospin and in-medium effects on the hyperon production and kinetic energy spectra in the reaction of different heavy-ion reaction are investigated thoroughly. A repulsive hyperon-nucleon potential which is related to the hyperon momentum and baryon density from the chiral effective field theory is implemented into the model. The correction on threshold energy of the elementary hyperon cross section is taken into account. It is found that the\begin{document}$ \varSigma $\end{document} ![]()
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\begin{document}$\varSigma^{-}$\end{document} ![]()
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\begin{document}$\varSigma^{+}$\end{document} ![]()
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\begin{document}$\varSigma^{-}$\end{document} ![]()
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\begin{document}$\varSigma^{+}$\end{document} ![]()
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Within the framework of Lanzhou quantum molecular dynamics(LQMD) transport model, the isospin and in-medium effects on the hyperon production and kinetic energy spectra in the reaction of different heavy-ion reaction are investigated thoroughly. A repulsive hyperon-nucleon potential which is related to the hyperon momentum and baryon density from the chiral effective field theory is implemented into the model. The correction on threshold energy of the elementary hyperon cross section is taken into account. It is found that the
2022, 39(1): 16-22.
doi: 10.11804/NuclPhysRev.39.2021071
Abstract:
The effect of the two forms of momentum-dependence potential on the directed flow and elliptic flow of neutron, proton, hydrogen isotopes, and charged particles are explored with the ultrarelativistic quantum molecular dynamics(UrQMD) model. The results show that the directed flow is almost insensitive to the momentum-dependence potential for the given incompressibility\begin{document}$ K_0$\end{document} ![]()
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The effect of the two forms of momentum-dependence potential on the directed flow and elliptic flow of neutron, proton, hydrogen isotopes, and charged particles are explored with the ultrarelativistic quantum molecular dynamics(UrQMD) model. The results show that the directed flow is almost insensitive to the momentum-dependence potential for the given incompressibility
2022, 39(1): 23-29.
doi: 10.11804/NuclPhysRev.39.2021081
Abstract:
Neutron-rich nuclei which are far away from the “ valley of stability ” on the chart of nuclides have always been a hotspot of nuclear physics. As a special kind of metastable excited states of deformed neutron-rich nuclei, high-K isomers usually are prolate, while oblate high-K isomers are rare. A recent experiment suggested that the\begin{document}$ {K}^{\mathrm{\pi }}={7}^{-} $\end{document} ![]()
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\begin{document}$ {K}^{\mathrm{\pi }}={9}^{-} $\end{document} ![]()
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\begin{document}$ {K}^{\mathrm{\pi }}={7}^{-} $\end{document} ![]()
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Neutron-rich nuclei which are far away from the “ valley of stability ” on the chart of nuclides have always been a hotspot of nuclear physics. As a special kind of metastable excited states of deformed neutron-rich nuclei, high-K isomers usually are prolate, while oblate high-K isomers are rare. A recent experiment suggested that the
2022, 39(1): 30-36.
doi: 10.11804/NuclPhysRev.39.2022001
Abstract:
We apply linear Regge trajectory and relatived quark model to revisit the low-lying excited singly-heavy mesons and explain the narrow mass splitting of these excited states to arise mainly from relativistic effect of the light quarks. The P-wave masses of the singly heavy mesons (D,\begin{document}$ {D_s} $\end{document} ![]()
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\begin{document}$ {B_s} $\end{document} ![]()
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\begin{document}$ {J^ + } $\end{document} ![]()
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\begin{document}$ J = 0 $\end{document} ![]()
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\begin{document}$ 1 $\end{document} ![]()
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\begin{document}$ 2 $\end{document} ![]()
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\begin{document}$ {B_s} $\end{document} ![]()
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\begin{document}$ {0^ + } $\end{document} ![]()
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\begin{document}$ {D_{s{\text{0}}}}\left( {{\text{2\;317}}} \right) $\end{document} ![]()
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\begin{document}$ {D_{s{\text{1}}}}\left( {{\text{2\;460}}} \right) $\end{document} ![]()
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We apply linear Regge trajectory and relatived quark model to revisit the low-lying excited singly-heavy mesons and explain the narrow mass splitting of these excited states to arise mainly from relativistic effect of the light quarks. The P-wave masses of the singly heavy mesons (D,
2022, 39(1): 37-44.
doi: 10.11804/NuclPhysRev.39.2021045
Abstract:
Long-term stable operation is one of difficult and frontier topics in the field of high-current linear accelerators. In this article, taking the China initiative Accelerator Driven System(CiADS) accelerator as an example, of whose virtual model implemented with TraceWin software by using simulation data, a segmented failure compensation method of superconducting(SC) cavity by artificial intelligence algorithm has been proposed. The neighboring elements of the failure cavities are used to rematch the beam envelope, while all the downstream cavities are used to compensate the beam energy. Compared with traditional optimization methods, this research can realize the failure compensation of low energy SC section, and has the advantages of fast calculation speed and strong versatility. It provides new feasibility for the practical application of component failure compensation.
Long-term stable operation is one of difficult and frontier topics in the field of high-current linear accelerators. In this article, taking the China initiative Accelerator Driven System(CiADS) accelerator as an example, of whose virtual model implemented with TraceWin software by using simulation data, a segmented failure compensation method of superconducting(SC) cavity by artificial intelligence algorithm has been proposed. The neighboring elements of the failure cavities are used to rematch the beam envelope, while all the downstream cavities are used to compensate the beam energy. Compared with traditional optimization methods, this research can realize the failure compensation of low energy SC section, and has the advantages of fast calculation speed and strong versatility. It provides new feasibility for the practical application of component failure compensation.
2022, 39(1): 45-53.
doi: 10.11804/NuclPhysRev.39.2021049
Abstract:
The low-level radio frequency control system(LLRF) is mainly used to control the electric field and resonate frequency of the accelerating cavity to ensure the stable operation of the accelerator and output high-quality beam. The LLRF software provides a graphical user interface, and realize the functions such as data display and storage, as well as some algorithm like automatic logic and so on. A well-designed LLRF software improves the operability of the LLRF and reduces the amount of manual work and failure rate. This paper introduces the development and design of LLRF software for China spallation neutron source(CSNS) linac, mainly including feedforward automatic calculation, automatic frequency control of acceleration cavity, frequency detuning algorithm, automatic RF power up and so on. Finally, the amplitude and phase stability index of the system is better than the required design index, and meets the requirements of long-term stable operation.
The low-level radio frequency control system(LLRF) is mainly used to control the electric field and resonate frequency of the accelerating cavity to ensure the stable operation of the accelerator and output high-quality beam. The LLRF software provides a graphical user interface, and realize the functions such as data display and storage, as well as some algorithm like automatic logic and so on. A well-designed LLRF software improves the operability of the LLRF and reduces the amount of manual work and failure rate. This paper introduces the development and design of LLRF software for China spallation neutron source(CSNS) linac, mainly including feedforward automatic calculation, automatic frequency control of acceleration cavity, frequency detuning algorithm, automatic RF power up and so on. Finally, the amplitude and phase stability index of the system is better than the required design index, and meets the requirements of long-term stable operation.
2022, 39(1): 54-64.
doi: 10.11804/NuclPhysRev.39.2021011
Abstract:
Accelerator mass spectrometry(AMS) is the most sensitivity measurement technique for the long-lived radioisotopes up to now and has been widely used in archaeology, geology, environment, physics and other fields. With the development of technology, the AMS devices are developing towards the miniaturization. The miniaturization of AMS device has been well applied. In this paper, the key technologies of AMS for long-life radionuclide high-sensitivity analysis are comprehensively discussed, and the characteristic technologies used in the miniaturized AMS system are systematically introduced. Finally, the devices and performances of two miniaturization AMS system developed by China Institute of Atomic Energy are discussed.
Accelerator mass spectrometry(AMS) is the most sensitivity measurement technique for the long-lived radioisotopes up to now and has been widely used in archaeology, geology, environment, physics and other fields. With the development of technology, the AMS devices are developing towards the miniaturization. The miniaturization of AMS device has been well applied. In this paper, the key technologies of AMS for long-life radionuclide high-sensitivity analysis are comprehensively discussed, and the characteristic technologies used in the miniaturized AMS system are systematically introduced. Finally, the devices and performances of two miniaturization AMS system developed by China Institute of Atomic Energy are discussed.
2022, 39(1): 65-72.
doi: 10.11804/NuclPhysRev.39.2021035
Abstract:
To improve the ability of particle identification of the RIBLL2 separator at the HIRFL-CSR complex, a new high-performance detector for measuring fragment starting time and position at the F1 dispersive plane has been constructed and installed, and a method for achieving precise Bρ determination has been developed using the experimentally derived ion-optical transfer matrix elements from the measured position and ToF information. Using the high-performance detectors and the precise Bρ determination method, the fragments produced by the fragmentation of 78Kr at 300 MeV/nucleon were identified clearly at the RIBLL2-ETF under full momentum acceptance. The atomic number Z resolution of σZ~0.19 and the mass-to-charge ratio A/Q resolution of σA/Q~5.8×10−3 were obtained for the 75As33+ fragment. This great improvement will increase the collection efficiency of exotic nuclei, extend the range of nuclei of interest from the A<40 mass region up to the A~80 mass region, and promote the development of radioactive nuclear beam experiments at the RIBLL2 separator.
To improve the ability of particle identification of the RIBLL2 separator at the HIRFL-CSR complex, a new high-performance detector for measuring fragment starting time and position at the F1 dispersive plane has been constructed and installed, and a method for achieving precise Bρ determination has been developed using the experimentally derived ion-optical transfer matrix elements from the measured position and ToF information. Using the high-performance detectors and the precise Bρ determination method, the fragments produced by the fragmentation of 78Kr at 300 MeV/nucleon were identified clearly at the RIBLL2-ETF under full momentum acceptance. The atomic number Z resolution of σZ~0.19 and the mass-to-charge ratio A/Q resolution of σA/Q~5.8×10−3 were obtained for the 75As33+ fragment. This great improvement will increase the collection efficiency of exotic nuclei, extend the range of nuclei of interest from the A<40 mass region up to the A~80 mass region, and promote the development of radioactive nuclear beam experiments at the RIBLL2 separator.
2022, 39(1): 73-80.
doi: 10.11804/NuclPhysRev.39.2021039
Abstract:
A statistical correction method is proposed to suppress the pile-up background events in data analysis. This method is verified by a cosmic muon lifetime measurement experiment, achieved by a plastic scintillator detector using the timing coincidence method, where dominant background events originate from pile up muons and electronic noise. To complement the intrinsic shortcoming of relatively rare decay events from registered cosmic muon events in the local laboratory, Monte Carlo simulation is applied to generate large samples in order to cross check the new method. The measurement of the muon lifetime in our setup gives a result of\begin{document}$\tau_\mu^{\rm exp} = 2.19 \pm 0.07 \ \mu \text{s}$\end{document} ![]()
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\begin{document}$\tau_{\mu}' = 2.27 \pm 0.07 ~\mu \text{s}$\end{document} ![]()
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A statistical correction method is proposed to suppress the pile-up background events in data analysis. This method is verified by a cosmic muon lifetime measurement experiment, achieved by a plastic scintillator detector using the timing coincidence method, where dominant background events originate from pile up muons and electronic noise. To complement the intrinsic shortcoming of relatively rare decay events from registered cosmic muon events in the local laboratory, Monte Carlo simulation is applied to generate large samples in order to cross check the new method. The measurement of the muon lifetime in our setup gives a result of
2022, 39(1): 81-87.
doi: 10.11804/NuclPhysRev.39.2021023
Abstract:
As one of the key components in high precision time measurement based on discrimination and time digitization, the time-to-digital converter(TDC) is widely used in many fields. This paper presents the design and testing of a DLL based TDC prototype ASIC named DHR TDC with a large detectable range and high resolution in 180 nm CMOS technology. A test module was designed and the test platform was set up for the TDC performance evaluation. Test results indicate that this TDC achieves a time resolution of better than 60 ps RMS with an averaged bin size of around 156 ps, as well as a measurement dynamic range of up to 20 µs, and its differential nonlinearity(DNL) and integral nonlinearity(INL) are better than 0.13 LSB and 0.15 LSB, respectively.
As one of the key components in high precision time measurement based on discrimination and time digitization, the time-to-digital converter(TDC) is widely used in many fields. This paper presents the design and testing of a DLL based TDC prototype ASIC named DHR TDC with a large detectable range and high resolution in 180 nm CMOS technology. A test module was designed and the test platform was set up for the TDC performance evaluation. Test results indicate that this TDC achieves a time resolution of better than 60 ps RMS with an averaged bin size of around 156 ps, as well as a measurement dynamic range of up to 20 µs, and its differential nonlinearity(DNL) and integral nonlinearity(INL) are better than 0.13 LSB and 0.15 LSB, respectively.
2022, 39(1): 88-94.
doi: 10.11804/NuclPhysRev.39.2021040
Abstract:
To monitor the irradiation dose and position of heavy ion beam with the imaging methods in the treatment of the heavy ion tumor radiotherapy, an In-Beam Positron Emission Tomography(In-beam PET) will be mounted in Heavy-Ion Medical Machine(HIMM) in China. In In-beam PET, the event data is collected by the detector array and digitized by front-end Data Acquisition Units(DAQU). Then digitized data will be sent to the Central Processing Module (CPM) through the optical fiber link, and finally transmitted to the host sever via the PCIe interface. A single DAQU can obtain a maximum data rate of 2.2 Gbit/s, which imposes high requirements on the transmission bandwidth of the optical fiber link accordingly. As the core of DAQU is Cyclone V FPGA and the core of CPM is Kintex-7 FPGA, the realization of reliable real-time communication between FPGAs of different companies is a challenge. This paper presents a new design and the implementation of the optical fiber link for In-beam PET, aiming to realize the stable communication between Cyclone V FPGA and Kintex-7 FPGA. The performance of the design shows that it can meet the demand of high stability and high accuracy in real-time.
To monitor the irradiation dose and position of heavy ion beam with the imaging methods in the treatment of the heavy ion tumor radiotherapy, an In-Beam Positron Emission Tomography(In-beam PET) will be mounted in Heavy-Ion Medical Machine(HIMM) in China. In In-beam PET, the event data is collected by the detector array and digitized by front-end Data Acquisition Units(DAQU). Then digitized data will be sent to the Central Processing Module (CPM) through the optical fiber link, and finally transmitted to the host sever via the PCIe interface. A single DAQU can obtain a maximum data rate of 2.2 Gbit/s, which imposes high requirements on the transmission bandwidth of the optical fiber link accordingly. As the core of DAQU is Cyclone V FPGA and the core of CPM is Kintex-7 FPGA, the realization of reliable real-time communication between FPGAs of different companies is a challenge. This paper presents a new design and the implementation of the optical fiber link for In-beam PET, aiming to realize the stable communication between Cyclone V FPGA and Kintex-7 FPGA. The performance of the design shows that it can meet the demand of high stability and high accuracy in real-time.
2022, 39(1): 95-100.
doi: 10.11804/NuclPhysRev.39.2021029
Abstract:
Simulation programmes which combine the quantum model and Monte Carlo method by Schulz et al. are developed to reconstruct the experimental spectra of the single ionization in collisions between 100 MeV/u\begin{document}${\rm{C}}^{6+}$\end{document} ![]()
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\begin{document}${\rm{C}}^{6+}$\end{document} ![]()
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Simulation programmes which combine the quantum model and Monte Carlo method by Schulz et al. are developed to reconstruct the experimental spectra of the single ionization in collisions between 100 MeV/u
2022, 39(1): 101-107.
doi: 10.11804/NuclPhysRev.39.2021030
Abstract:
A new type of F/M steel (SIMP steel) and two kinds of ODS steels (MA956 and Eurofer-ODS steels) were irradiated by 2 MeV He ions to fluence of 1×1017 ions/cm2 at 500 and 600 °C. After irradiation, swelling behaviors and effect of nanostructures (such as grain boundaries, precipitates and nano-oxide particles) on the nucleation and growth of He bubbles were studied by transmission electron microscope. The results show that both SIMP and Eurofer-ODS steels exhibit better swelling resistance than MA956 ODS steel at 500 °C, because the grain boundaries or precipitates pronouncedly inhibit the growth of He bubbles. The Eurofer-ODS steel shows best swelling resistance due to the inhibition of He bubbles growth by the grain boundary and oxide interface at 600 °C. The present work shows that nanostructures in materials inhibit the process of He bubble growth under high He fluence conditions, but the degree of inhibition varies with different materials.
A new type of F/M steel (SIMP steel) and two kinds of ODS steels (MA956 and Eurofer-ODS steels) were irradiated by 2 MeV He ions to fluence of 1×1017 ions/cm2 at 500 and 600 °C. After irradiation, swelling behaviors and effect of nanostructures (such as grain boundaries, precipitates and nano-oxide particles) on the nucleation and growth of He bubbles were studied by transmission electron microscope. The results show that both SIMP and Eurofer-ODS steels exhibit better swelling resistance than MA956 ODS steel at 500 °C, because the grain boundaries or precipitates pronouncedly inhibit the growth of He bubbles. The Eurofer-ODS steel shows best swelling resistance due to the inhibition of He bubbles growth by the grain boundary and oxide interface at 600 °C. The present work shows that nanostructures in materials inhibit the process of He bubble growth under high He fluence conditions, but the degree of inhibition varies with different materials.
2022, 39(1): 108-113.
doi: 10.11804/NuclPhysRev.39.2021032
Abstract:
Molecular dynamics(MD) simulations were performed to investigate the effects of grain size on the mechanical properties of nano-polycrystalline iron doped with helium(He). Simulated X-ray diffraction(XRD) was used to explore the relationship between the generation of cracks and the distortion of crystal structural in nano-polycrystalline iron during tensile deformation. The simulation results show that the peak stresses are obviously decreased due to the introduction of He atoms into the grain boundaries of nano-polycrystalline iron. In addition, it is observed that the generation and growth of intergranular cracks are significantly enhanced by He atoms which are distributed at grain boundary(GB) regions during tensile simulation. The results suggest that the intergranular cracks are promoted by GB He atoms, and the size and number of cracks increase with the increasing grain size of nano-polycrystalline iron. The separation of peak {200} and {211} are significantly observed in the XRD patterns during loading. The diffraction angle of subpeaks is higher in the XRD patterns of nano-polycrystalline iron with GB He than in that without He during the strain range from 6% to 10%, and the diffraction angle of subpeaks and the growth of cracks increase with the increasing grain size. It is demonstrated that the degradation of mechanical property caused by intergranular cracks has close relationship with the change of structural distortion obtained by simulated XRD patterns in nano-polycrystalline iron.
Molecular dynamics(MD) simulations were performed to investigate the effects of grain size on the mechanical properties of nano-polycrystalline iron doped with helium(He). Simulated X-ray diffraction(XRD) was used to explore the relationship between the generation of cracks and the distortion of crystal structural in nano-polycrystalline iron during tensile deformation. The simulation results show that the peak stresses are obviously decreased due to the introduction of He atoms into the grain boundaries of nano-polycrystalline iron. In addition, it is observed that the generation and growth of intergranular cracks are significantly enhanced by He atoms which are distributed at grain boundary(GB) regions during tensile simulation. The results suggest that the intergranular cracks are promoted by GB He atoms, and the size and number of cracks increase with the increasing grain size of nano-polycrystalline iron. The separation of peak {200} and {211} are significantly observed in the XRD patterns during loading. The diffraction angle of subpeaks is higher in the XRD patterns of nano-polycrystalline iron with GB He than in that without He during the strain range from 6% to 10%, and the diffraction angle of subpeaks and the growth of cracks increase with the increasing grain size. It is demonstrated that the degradation of mechanical property caused by intergranular cracks has close relationship with the change of structural distortion obtained by simulated XRD patterns in nano-polycrystalline iron.
2022, 39(1): 114-120.
doi: 10.11804/NuclPhysRev.39.2021033
Abstract:
In carbon-ion radiotherapy, a variety of secondary particles are produced when carbon-ion beams pass through beam-line components during the dose delivery process and form an external radiation field. The predominant part of external radiation is from neutrons. As high LET radiation, low-dose neutron exposures have high relative biological effectiveness. Reducing the secondary neutrons can help to curb the risks of normal tissue complications and secondary cancers. The fluence and dose equivalent spectrums of exogenous neutrons induced by the passive beam delivery system of carbon ion therapy at different locations around the isocenter were simulated using the Monte Carlo method to evaluate the dose equivalent contribution of neutron radiation; The influence of the different collimating aperture sizes on the secondary neutron dose equivalent was also investigated. The simulation results show that high-energy neutrons had a certain contribution to the total neutron dose equivalent of the simulated locations, which account for up to 26%. Under real treatment conditions, as the collimating aperture size increased from closed to 15 cm×15 cm, the neutron dose equivalent decreased by approximately 85% at the isocenter and laterally distal locations, and about 70% at the distal locations in the beam direction. These results can be used to guide the study of secondary neutrons under different treatment conditions, and provide a basis for assessing non-therapeutic radiation received by patients under treatment conditions.
In carbon-ion radiotherapy, a variety of secondary particles are produced when carbon-ion beams pass through beam-line components during the dose delivery process and form an external radiation field. The predominant part of external radiation is from neutrons. As high LET radiation, low-dose neutron exposures have high relative biological effectiveness. Reducing the secondary neutrons can help to curb the risks of normal tissue complications and secondary cancers. The fluence and dose equivalent spectrums of exogenous neutrons induced by the passive beam delivery system of carbon ion therapy at different locations around the isocenter were simulated using the Monte Carlo method to evaluate the dose equivalent contribution of neutron radiation; The influence of the different collimating aperture sizes on the secondary neutron dose equivalent was also investigated. The simulation results show that high-energy neutrons had a certain contribution to the total neutron dose equivalent of the simulated locations, which account for up to 26%. Under real treatment conditions, as the collimating aperture size increased from closed to 15 cm×15 cm, the neutron dose equivalent decreased by approximately 85% at the isocenter and laterally distal locations, and about 70% at the distal locations in the beam direction. These results can be used to guide the study of secondary neutrons under different treatment conditions, and provide a basis for assessing non-therapeutic radiation received by patients under treatment conditions.
2022, 39(1): 121-126.
doi: 10.11804/NuclPhysRev.39.2021064
Abstract:
The control method for the reactor power by adjusting the beam intensity has been studied for the China initiative Accelerator Driven System(CiADS) facility. In the proposed control method, the beam intensity can be adjusted continuously by changing the aperture size. The aperture size is adjusted automatically based on the PID controllers by comparing the setting power with the measured value. To evaluate the proposed method, a CiADS core model is built based on the point reactor kinetics equation. The simulations based on the CiADS core model have indicated that the reactor power varies with the beam intensity and that the reactor power can be controlled effectively by adjusting the aperture size. Finally, the automatic and manual control functions for the reactor power have been implemented in a Distributed Control System(DCS). In the automatic control function, the measured value of the reactor power is sent to the input-output model of DCS system and is compared with the setting value. Then, the new value of the aperture size is calculated with the PID controller and is sent the drive motor system of the aperture. In addition, the reactor power can also be adjusted by setting manually the aperture size in the control room.
The control method for the reactor power by adjusting the beam intensity has been studied for the China initiative Accelerator Driven System(CiADS) facility. In the proposed control method, the beam intensity can be adjusted continuously by changing the aperture size. The aperture size is adjusted automatically based on the PID controllers by comparing the setting power with the measured value. To evaluate the proposed method, a CiADS core model is built based on the point reactor kinetics equation. The simulations based on the CiADS core model have indicated that the reactor power varies with the beam intensity and that the reactor power can be controlled effectively by adjusting the aperture size. Finally, the automatic and manual control functions for the reactor power have been implemented in a Distributed Control System(DCS). In the automatic control function, the measured value of the reactor power is sent to the input-output model of DCS system and is compared with the setting value. Then, the new value of the aperture size is calculated with the PID controller and is sent the drive motor system of the aperture. In addition, the reactor power can also be adjusted by setting manually the aperture size in the control room.
2022, 39(1): 127-133.
doi: 10.11804/NuclPhysRev.39.2021077
Abstract:
Pulsed neutron source method(PNS) is an important technique for the reactivity measurement of accelerator driven sub-critical systems. The CiADS sub-critical reactor model is established using Monte Carlo code to simulate the neutron transport process bombarded by pulsed proton beam, and the time spectrum of neutron flux is obtained. A code is developed by Python programming language to finish the pulsed neutron superposition process. It can obtain a stable delayed neutron background and the variation of neutron flux at different positions of the core under the continuously pulsed period proton injection. The reactivity measurement simulation of the sub-critical reactor by PNS method come true. Subsequently, the PNS method is used to simulate the reactivity of the CiADS core under different sub-criticalities and detection positions, and the results is compared with the reference values. It shows that this method can accurately predict the reactivity of sub-critical reactor at high effective multiplication factor (\begin{document}$ k_{\mathrm{eff}} >0.94$\end{document} ![]()
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Pulsed neutron source method(PNS) is an important technique for the reactivity measurement of accelerator driven sub-critical systems. The CiADS sub-critical reactor model is established using Monte Carlo code to simulate the neutron transport process bombarded by pulsed proton beam, and the time spectrum of neutron flux is obtained. A code is developed by Python programming language to finish the pulsed neutron superposition process. It can obtain a stable delayed neutron background and the variation of neutron flux at different positions of the core under the continuously pulsed period proton injection. The reactivity measurement simulation of the sub-critical reactor by PNS method come true. Subsequently, the PNS method is used to simulate the reactivity of the CiADS core under different sub-criticalities and detection positions, and the results is compared with the reference values. It shows that this method can accurately predict the reactivity of sub-critical reactor at high effective multiplication factor (
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