2023 Vol. 40, No. 3
Display Method:
2023, 40(3): 327-340.
doi: 10.11804/NuclPhysRev.40.2022132
Abstract:
Proton decay of nuclei beyond the proton dripline provides a key spectroscopic tool to investigate the nuclear structures and nuclear stabilities under extreme isospin conditions. Recent experimental studies on the nuclear proton decay are first summarized, followed by the brief introduction of the major approaches of producing nuclei beyond the proton dripline, the main experimental methods of studying their proton decays, and the understanding of the decay mechanisms of dripline nuclei. On this basis, our recent experimental research on the four-proton decay of 18Mg is presented. The new isotope 18Mg, which is located two neutrons beyond the proton dripline, has been experimentally observed for the first time by using the invariant mass method. The decay energies and decay widths of the ground and first 2+ states in 18Mg have been determined. As the measured excitation energy of the\begin{document}$2_1^{\text{ + }}$\end{document} ![]()
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Proton decay of nuclei beyond the proton dripline provides a key spectroscopic tool to investigate the nuclear structures and nuclear stabilities under extreme isospin conditions. Recent experimental studies on the nuclear proton decay are first summarized, followed by the brief introduction of the major approaches of producing nuclei beyond the proton dripline, the main experimental methods of studying their proton decays, and the understanding of the decay mechanisms of dripline nuclei. On this basis, our recent experimental research on the four-proton decay of 18Mg is presented. The new isotope 18Mg, which is located two neutrons beyond the proton dripline, has been experimentally observed for the first time by using the invariant mass method. The decay energies and decay widths of the ground and first 2+ states in 18Mg have been determined. As the measured excitation energy of the
2023, 40(3): 341-347.
doi: 10.11804/NuclPhysRev.40.2022134
Abstract:
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2023, 40(3): 348-355.
doi: 10.11804/NuclPhysRev.40.2022004
Abstract:
Half-lives of spontaneous nuclear decay processes are calculated by a generalized liquid drop model (GLDM). The potential barrier is constructed by a GLDM, taking into account the nuclear proximity, the mass asymmetry, the accurate nuclear radius, the phenomenological shell and pairing correction. The GLDM model is to continue reproducing the experimental data for\begin{document}$\alpha$\end{document} ![]()
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Half-lives of spontaneous nuclear decay processes are calculated by a generalized liquid drop model (GLDM). The potential barrier is constructed by a GLDM, taking into account the nuclear proximity, the mass asymmetry, the accurate nuclear radius, the phenomenological shell and pairing correction. The GLDM model is to continue reproducing the experimental data for
2023, 40(3): 356-361.
doi: 10.11804/NuclPhysRev.40.2023005
Abstract:
The reaction kinetics of weakly bound nuclei in the nearbarrier energy region is currently one of the hotspots in nuclear physics research.The quasielastic scattering of the\begin{document}$^{7}{\rm{Be}}$\end{document} ![]()
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The reaction kinetics of weakly bound nuclei in the nearbarrier energy region is currently one of the hotspots in nuclear physics research.The quasielastic scattering of the
2023, 40(3): 362-369.
doi: 10.11804/NuclPhysRev.40.2022052
Abstract:
In this paper, based on the KONUS dynamics theory, the beam dynamics design of a compact room-temperature cross-bar drift tube linear accelerator(CH-DTL) operating in pulsed mode is completed, and the key issues are carefully investigated. This DTL operates at 325 MHz, contains 29 acceleration gaps, and has a dynamics length of 1.3 m. It can accelerate\begin{document}$^{12}{\rm{C}}^{5+}$\end{document} ![]()
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In this paper, based on the KONUS dynamics theory, the beam dynamics design of a compact room-temperature cross-bar drift tube linear accelerator(CH-DTL) operating in pulsed mode is completed, and the key issues are carefully investigated. This DTL operates at 325 MHz, contains 29 acceleration gaps, and has a dynamics length of 1.3 m. It can accelerate
2023, 40(3): 370-376.
doi: 10.11804/NuclPhysRev.40.2022105
Abstract:
Beam envelope instability driven by space charge is an important factor causing the beam loss of intense beam superconducting linear accelerator. Zero-current period phase advance less than 90 degrees is the design principle of strong current superconducting linear accelerator generally followed in the world, and this design principle is proposed without considering acceleration. In this paper, the periodic instability under the condition of acceleration effect is analyzed by dynamic simulation. The results show that reasonable choice of focus change rate and acceleration gradient can reduce the influence of envelope instability, so that the strict limit of physical design period phase advance of less than 90 degrees can be broken and the acceleration efficiency of the accelerator can be improved.
Beam envelope instability driven by space charge is an important factor causing the beam loss of intense beam superconducting linear accelerator. Zero-current period phase advance less than 90 degrees is the design principle of strong current superconducting linear accelerator generally followed in the world, and this design principle is proposed without considering acceleration. In this paper, the periodic instability under the condition of acceleration effect is analyzed by dynamic simulation. The results show that reasonable choice of focus change rate and acceleration gradient can reduce the influence of envelope instability, so that the strict limit of physical design period phase advance of less than 90 degrees can be broken and the acceleration efficiency of the accelerator can be improved.
2023, 40(3): 377-384.
doi: 10.11804/NuclPhysRev.40.2022070
Abstract:
The SSW(Single Stretched Wire) method is a high-quality magnetic field measurement technique that offers benefits like excellent positioning precision, quick measurement and tiny aperture magnets measurement. It is widely employed in the field of accelerator engineering magnetic field measurement and has been adopted by numerous overseas institutions. In this study, a set of SSW magnetic field measurement platforms are constructed based on the theory of the SSW measurement method, and a number of tests are run on a standard quadrupole to examine the signal processing technique and confirm the measurement accuracy. The findings demonstrate that the SSW system's magnetic center measurement repeatability is better than ±6 μm, which satisfies the test requirements for the majority of accelerator projects. In the future, this system will continue to be improved and widely used in the magnetic field measurement of related devices.
The SSW(Single Stretched Wire) method is a high-quality magnetic field measurement technique that offers benefits like excellent positioning precision, quick measurement and tiny aperture magnets measurement. It is widely employed in the field of accelerator engineering magnetic field measurement and has been adopted by numerous overseas institutions. In this study, a set of SSW magnetic field measurement platforms are constructed based on the theory of the SSW measurement method, and a number of tests are run on a standard quadrupole to examine the signal processing technique and confirm the measurement accuracy. The findings demonstrate that the SSW system's magnetic center measurement repeatability is better than ±6 μm, which satisfies the test requirements for the majority of accelerator projects. In the future, this system will continue to be improved and widely used in the magnetic field measurement of related devices.
2023, 40(3): 385-400.
doi: 10.11804/NuclPhysRev.40.2022099
Abstract:
Betavoltaic batteries have great application potential in the field of low-power electronic devices, such as micro-electro-mechanical-systems(MEMS), due to their long service life, high power density, small scale, strong environmental adaptability and sustainable power supply. At present, the structure design of this type of isotope battery is unsatisfactory, the carrier recombination is serious and the output performance is low. In view of the existing deficiencies, this paper introduced the research progress on the optimization design of betavoltaic batteries in the Isotope Battery Research Group of Jilin University. By using the Monte Carlo code and the finite element analysis software, a simulation model which can accurately predict the output performance of this type of isotope battery was established, and the transport and collection characteristics of radiation-induced carriers were investigated. GaAs was selected as the energy conversion semiconductor material for the experimental preparation of isotope batteries, and the hole/electron transport layers were introduced to the GaAs-based energy converter to enhance the transport and collection of radiation-induced carriers. Moreover, the established simulation model was used to predict the output performance of betavoltaic batteries based on wide-bandgap semiconductor materials. The effect factors on battery conversion efficiency were analyzed, and the relationship between battery conversion efficiency and semiconductor material bandgap was clarified. In addition, a core-shell nanowire betavoltaic battery was proposed to improve the absorption rate of beta particles and reduce the surface recombination rate of radiation-induced carriers. Finally, in order to further improve the output performance of betavoltaic batteries, the ideal of energy carrying-energy converting integration was proposed.
Betavoltaic batteries have great application potential in the field of low-power electronic devices, such as micro-electro-mechanical-systems(MEMS), due to their long service life, high power density, small scale, strong environmental adaptability and sustainable power supply. At present, the structure design of this type of isotope battery is unsatisfactory, the carrier recombination is serious and the output performance is low. In view of the existing deficiencies, this paper introduced the research progress on the optimization design of betavoltaic batteries in the Isotope Battery Research Group of Jilin University. By using the Monte Carlo code and the finite element analysis software, a simulation model which can accurately predict the output performance of this type of isotope battery was established, and the transport and collection characteristics of radiation-induced carriers were investigated. GaAs was selected as the energy conversion semiconductor material for the experimental preparation of isotope batteries, and the hole/electron transport layers were introduced to the GaAs-based energy converter to enhance the transport and collection of radiation-induced carriers. Moreover, the established simulation model was used to predict the output performance of betavoltaic batteries based on wide-bandgap semiconductor materials. The effect factors on battery conversion efficiency were analyzed, and the relationship between battery conversion efficiency and semiconductor material bandgap was clarified. In addition, a core-shell nanowire betavoltaic battery was proposed to improve the absorption rate of beta particles and reduce the surface recombination rate of radiation-induced carriers. Finally, in order to further improve the output performance of betavoltaic batteries, the ideal of energy carrying-energy converting integration was proposed.
2023, 40(3): 401-409.
doi: 10.11804/NuclPhysRev.40.2022104
Abstract:
The radioactive source terms are often distributed inside the detection target, which are difficult to be located and measured directly. In order to monitor the dose level of radioactive source terms during the waste treatment and nuclear facilities decommissioning, in this research we propose an activity inversion method of radioactive source terms based on convolutional neural network(CNN), and establishes the correlation between the radiation field flux and the source term activity. In this method, source terms calculation models are established for waste steel barrel, concrete barrel with built-in filter, square box with built-in air filter and pippeline in primary circuit of reactor, and the samples are learned based on CNN for source term activity inversion. Compared the activity inversion results with the simulated measured values, the average error can be controlled at about 10%, which verifies the effectiveness of the proposed method. In addition, the accuracy of prediction and stability performance of this method are superior to other activity inversion methods. Which proves that the combination of CNN and source term activity inversion has high application value in the fields of waste disposal and nuclear facilities decommissioning.
The radioactive source terms are often distributed inside the detection target, which are difficult to be located and measured directly. In order to monitor the dose level of radioactive source terms during the waste treatment and nuclear facilities decommissioning, in this research we propose an activity inversion method of radioactive source terms based on convolutional neural network(CNN), and establishes the correlation between the radiation field flux and the source term activity. In this method, source terms calculation models are established for waste steel barrel, concrete barrel with built-in filter, square box with built-in air filter and pippeline in primary circuit of reactor, and the samples are learned based on CNN for source term activity inversion. Compared the activity inversion results with the simulated measured values, the average error can be controlled at about 10%, which verifies the effectiveness of the proposed method. In addition, the accuracy of prediction and stability performance of this method are superior to other activity inversion methods. Which proves that the combination of CNN and source term activity inversion has high application value in the fields of waste disposal and nuclear facilities decommissioning.
2023, 40(3): 410-417.
doi: 10.11804/NuclPhysRev.40.2022087
Abstract:
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2023, 40(3): 418-425.
doi: 10.11804/NuclPhysRev.40.2022041
Abstract:
NICA(Nuclotron-based Ion Collider fAcility) is a heavy ion collider based on superconducting particle accelerator developed by China and Russia. According to the requirements of data receiving and sending in NICA ROC(NICA Readout and Control) ASIC, designed for ITS front-end data collection and transmission in NICA MPD, a Low Voltage Differential Signaling(LVDS) high-speed serial interface circuit is designed as the data interface between NICA ROC and front-end readout ASICs, and the pre-emphasis technique is employed to reduce the inter-symbol interference. Based on 130 nm CMOS technology, the circuit design, simulation, layout design, and tape-out of LVDS receiver and driver have been completed. A test system is designed for this high-speed serial interface chip. The test results show that the LVDS transceiver can achieve 800 Mbps receiving and transmitting data rate, and the differential output voltage is about 260 mV, with the Bit Error Ratio(BER) less than\begin{document}${1 \times 10}^{-13}$\end{document} ![]()
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NICA(Nuclotron-based Ion Collider fAcility) is a heavy ion collider based on superconducting particle accelerator developed by China and Russia. According to the requirements of data receiving and sending in NICA ROC(NICA Readout and Control) ASIC, designed for ITS front-end data collection and transmission in NICA MPD, a Low Voltage Differential Signaling(LVDS) high-speed serial interface circuit is designed as the data interface between NICA ROC and front-end readout ASICs, and the pre-emphasis technique is employed to reduce the inter-symbol interference. Based on 130 nm CMOS technology, the circuit design, simulation, layout design, and tape-out of LVDS receiver and driver have been completed. A test system is designed for this high-speed serial interface chip. The test results show that the LVDS transceiver can achieve 800 Mbps receiving and transmitting data rate, and the differential output voltage is about 260 mV, with the Bit Error Ratio(BER) less than
2023, 40(3): 426-432.
doi: 10.11804/NuclPhysRev.40.2022073
Abstract:
To solve the measurement of the weak coupled signals from beam position monitors in a heavy ion accelerator with low intensity beam, a broad band low noise preamplifier with a high input impedance is designed and developed, which has a broad band response over almost 2 decades of frequency. This design is based on a cascade multistage amplification.The input stage, consisting of 2 folded N-channel junction field effect transistors (N-JFET), adopts a cascade and source following structure to minimize the input voltage noise. A high voltage open-loop gain is obtained by using the characteristic impedance of a constant current source. The output stage is a current mode feedback op-amp which provides a broad band frequency response and enough output power. The whole circuit has a high sensitivity, low noise and distortion. From the measurement, the achieved gain is 36.2 dB with a flatness of less than ±0.3 dB from 34 kHz to 38.47 MHz. The input voltage noise density is 0.76 nV/\begin{document}$ \sqrt{\mathrm{H}\mathrm{z}} $\end{document} ![]()
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To solve the measurement of the weak coupled signals from beam position monitors in a heavy ion accelerator with low intensity beam, a broad band low noise preamplifier with a high input impedance is designed and developed, which has a broad band response over almost 2 decades of frequency. This design is based on a cascade multistage amplification.The input stage, consisting of 2 folded N-channel junction field effect transistors (N-JFET), adopts a cascade and source following structure to minimize the input voltage noise. A high voltage open-loop gain is obtained by using the characteristic impedance of a constant current source. The output stage is a current mode feedback op-amp which provides a broad band frequency response and enough output power. The whole circuit has a high sensitivity, low noise and distortion. From the measurement, the achieved gain is 36.2 dB with a flatness of less than ±0.3 dB from 34 kHz to 38.47 MHz. The input voltage noise density is 0.76 nV/
2023, 40(3): 433-438.
doi: 10.11804/NuclPhysRev.40.2022071
Abstract:
A large number of pixel sensor chips are integrated on the beam detector in CEE experiment, in order to provide stable power voltage for these chips, and meet the high requirements of silicon pixel chips for small area and low power consumption of power supply circuit, a low voltage differential linear regulator(Low-dropout regulator, LDO) circuit compensated by a single Miller capacitor is realized in 130 nm CMOS process of GSMC. The proposed LDO based on the flip voltage following(Flipped Voltage Follower, FVF) structure which can achieve high stability, fast transient performance and ultra-low power consumption when the load current changes rapidly, and does not require off-chip capacitance when using small transistors. The experimental results show that the structure can drive a capacitive load of 0~100 pF when the load current is 20 mA, the line regulation is 3.3 mV/V, the quiescent current is 8.5 μA, and the layout area is only 103.5 μm×95.2 μm, which is suitable for highly complex detector system chips.
A large number of pixel sensor chips are integrated on the beam detector in CEE experiment, in order to provide stable power voltage for these chips, and meet the high requirements of silicon pixel chips for small area and low power consumption of power supply circuit, a low voltage differential linear regulator(Low-dropout regulator, LDO) circuit compensated by a single Miller capacitor is realized in 130 nm CMOS process of GSMC. The proposed LDO based on the flip voltage following(Flipped Voltage Follower, FVF) structure which can achieve high stability, fast transient performance and ultra-low power consumption when the load current changes rapidly, and does not require off-chip capacitance when using small transistors. The experimental results show that the structure can drive a capacitive load of 0~100 pF when the load current is 20 mA, the line regulation is 3.3 mV/V, the quiescent current is 8.5 μA, and the layout area is only 103.5 μm×95.2 μm, which is suitable for highly complex detector system chips.
2023, 40(3): 439-445.
doi: 10.11804/NuclPhysRev.40.2022081
Abstract:
The surface morphology, compositions, diameters, SiC grains and phase characteristics of SiC fibers irradiated by 246.8 MeV Ar16+ ions at different fluences were studied by means of field emission scanning electron microscopy(FE-SEM) and transmission electron microscopy(TEM). SEM results show that with the increase of the ion fluence, the diameter of SiC fiber first decreases and then increases. Moreover, at the highest fluence (2.7×1015 ions/cm2) irradiation, the surface roughness of SiC fiber increases evidently, and a brittle fracture occurred. Meanwhile, the carbon concentration on SiC fiber surface decreases and silicon concentration increases gradually with the ion fluences, accompanied by an adsorption of oxygen. TEM observations reveal that with an increase in ion fluences, the size of SiC grains first decreases and then increases, and some amorphization occurred. Furthermore, a transformation from the amorphization to the recrystallization was observed at the highest fluence irradiation.
The surface morphology, compositions, diameters, SiC grains and phase characteristics of SiC fibers irradiated by 246.8 MeV Ar16+ ions at different fluences were studied by means of field emission scanning electron microscopy(FE-SEM) and transmission electron microscopy(TEM). SEM results show that with the increase of the ion fluence, the diameter of SiC fiber first decreases and then increases. Moreover, at the highest fluence (2.7×1015 ions/cm2) irradiation, the surface roughness of SiC fiber increases evidently, and a brittle fracture occurred. Meanwhile, the carbon concentration on SiC fiber surface decreases and silicon concentration increases gradually with the ion fluences, accompanied by an adsorption of oxygen. TEM observations reveal that with an increase in ion fluences, the size of SiC grains first decreases and then increases, and some amorphization occurred. Furthermore, a transformation from the amorphization to the recrystallization was observed at the highest fluence irradiation.
2023, 40(3): 446-453.
doi: 10.11804/NuclPhysRev.40.2022084
Abstract:
As a vital sample preparation method for 14C graphite, the Zn-Fe reduction method has been widely used in various laboratories. However, there is still insufficient to improve the efficiency of graphite synthesis and reduce modern carbon pollution and other conditions test methodology. In this work, 14C graphite samples were prepared based on the Zn-Fe reduction method, and the experimented key parameters such as the reduction reaction temperature, reaction time, reagent dosage, Fe powder precleaned, and other factors were investigated and determined. For 14C graphite sample(≈1 mg), the amount of Zn is between 18~22 mg, and the amount of Fe is between 2.5~3.0 mg. Fe is precleaned by heating to 400 °C for 3h under air environment, and the reduction process is treated by heating at 650 °C for 8 h in a condensing graphite reduction furnace. Compared with background samples (commercial graphite) and standard samples (OX-II, IECA-C8, CSC) the results showed that the performance under this condition is better than before. It provides a basis for optimizing the 14C graphite preparation method, and lays a foundation for reducing the background level of trace 14C graphite prepared by Zn-Fe reduction method.
As a vital sample preparation method for 14C graphite, the Zn-Fe reduction method has been widely used in various laboratories. However, there is still insufficient to improve the efficiency of graphite synthesis and reduce modern carbon pollution and other conditions test methodology. In this work, 14C graphite samples were prepared based on the Zn-Fe reduction method, and the experimented key parameters such as the reduction reaction temperature, reaction time, reagent dosage, Fe powder precleaned, and other factors were investigated and determined. For 14C graphite sample(≈1 mg), the amount of Zn is between 18~22 mg, and the amount of Fe is between 2.5~3.0 mg. Fe is precleaned by heating to 400 °C for 3h under air environment, and the reduction process is treated by heating at 650 °C for 8 h in a condensing graphite reduction furnace. Compared with background samples (commercial graphite) and standard samples (OX-II, IECA-C8, CSC) the results showed that the performance under this condition is better than before. It provides a basis for optimizing the 14C graphite preparation method, and lays a foundation for reducing the background level of trace 14C graphite prepared by Zn-Fe reduction method.
2023, 40(3): 454-458.
doi: 10.11804/NuclPhysRev.40.2022107
Abstract:
By TCAD, the model for single event transient(SET) in SOI 4H-SiC FinFET device at 14 nm technology node was simulated. With the temperature range from 258 to 398 K, the influence of the bias voltages on SET was analyzed and the potential mechanism was also discussed. The simulation results indicate that due to the temperature increase, the Femi energy of the device changes and the band gap reduces, which increases the driven current. Then it leads to improve the immunity to SET. However, because of the bias voltage increase, the inner electrical field in the device enhances, resulting in the rate of the charge collected increase, which increases the sensitivity to SET. Due to the competitive relationship between the impacts of the temperature and the bias voltage on SET, when the temperature is 398 K and the bias voltage is 0.4 V, the weakest SET is obtained. Compared with SET obtained at 300 K and 0.8 V, the weakest one is with the relative decrements of the current peak and the collected charge being 22.77%, 50.83%, respectively.
By TCAD, the model for single event transient(SET) in SOI 4H-SiC FinFET device at 14 nm technology node was simulated. With the temperature range from 258 to 398 K, the influence of the bias voltages on SET was analyzed and the potential mechanism was also discussed. The simulation results indicate that due to the temperature increase, the Femi energy of the device changes and the band gap reduces, which increases the driven current. Then it leads to improve the immunity to SET. However, because of the bias voltage increase, the inner electrical field in the device enhances, resulting in the rate of the charge collected increase, which increases the sensitivity to SET. Due to the competitive relationship between the impacts of the temperature and the bias voltage on SET, when the temperature is 398 K and the bias voltage is 0.4 V, the weakest SET is obtained. Compared with SET obtained at 300 K and 0.8 V, the weakest one is with the relative decrements of the current peak and the collected charge being 22.77%, 50.83%, respectively.
2023, 40(3): 459-465.
doi: 10.11804/NuclPhysRev.40.2022106
Abstract:
SiC DT-MOSFET are prone to single event burnout(SEB) effect under heavy ion incident conditions. In this work, the TCAD program is used to simulate and calculate the spatial distribution of physical quantities such as drain curren, current densityt, lattice temperature, collision ionization and power density inside the device, and evaluate the influence of bias voltage on SEB effect. According to the simulation results, the transient current source formed by the incident ions turns on the parasitic bipolar transistor, the high drain source voltage maintains the avalanche effect in the device, and then the positive feedback mechanism of the device is established. Finally, the generated transient high current leads to the thermal damage of the device. Therefore, the main cause of SEB effect in SiC DT-MOSFET is the conduction of parasitic bipolar transistor and the establishment of positive feedback mechanism. In addition, the effect of strong electric field on collision ionization, lattice temperature and power density distribution is evaluated, and the reason why the peak region of power density corresponds to the peak region of lattice temperature is revealed, which provides data support for the anti nuclear reinforcement technology of SiC DT-MOSFET.
SiC DT-MOSFET are prone to single event burnout(SEB) effect under heavy ion incident conditions. In this work, the TCAD program is used to simulate and calculate the spatial distribution of physical quantities such as drain curren, current densityt, lattice temperature, collision ionization and power density inside the device, and evaluate the influence of bias voltage on SEB effect. According to the simulation results, the transient current source formed by the incident ions turns on the parasitic bipolar transistor, the high drain source voltage maintains the avalanche effect in the device, and then the positive feedback mechanism of the device is established. Finally, the generated transient high current leads to the thermal damage of the device. Therefore, the main cause of SEB effect in SiC DT-MOSFET is the conduction of parasitic bipolar transistor and the establishment of positive feedback mechanism. In addition, the effect of strong electric field on collision ionization, lattice temperature and power density distribution is evaluated, and the reason why the peak region of power density corresponds to the peak region of lattice temperature is revealed, which provides data support for the anti nuclear reinforcement technology of SiC DT-MOSFET.
2023, 40(3): 466-471.
doi: 10.11804/NuclPhysRev.40.2022067
Abstract:
Particle therapy is an advanced radiotherapy modality and quality assurance(QA) is an important technical stage linked to the safety and efficacy of particle therapy. For the QA of beam performance in particle therapy, irradiation field uniformity, size and position of the beam spot, and so on are concerned in the lateral direction while the relation between energy and range, dose distribution, and so on in the longitudinal direction. At present, the methods usually used in QA measurements for particle therapy are applied in a manner of single item or off-line analysis, thereby leading to low efficiency and poor real-time performance. To aid the technique of beam performance verification in particle therapy, a software system dedicated to the method of planar fluorecence detection was developed, where C++ programming language, the interface development framework Qt5 and the computer vision library OpenCV were adopted. Lateral particle beam parameter and longitudinal range (energy) verification could be conducted with the software system, and the raw data of carbon-ion beam performance obtained in the Heavy Ion Medical Machine(HIMM) in Wuwei were employed to conduct the testing of software algorithms and functions. The successful testing demonstrated that the software system could be used in integrated fluorecence detection systems and was able to realize modular analyses of particle beam performance. Thus, the versatile software system developed in this work expands the use scope of the planar fluorecence detection technique and improves the verification efficiency of beam therapeutic performance in particle therapy significantly.
Particle therapy is an advanced radiotherapy modality and quality assurance(QA) is an important technical stage linked to the safety and efficacy of particle therapy. For the QA of beam performance in particle therapy, irradiation field uniformity, size and position of the beam spot, and so on are concerned in the lateral direction while the relation between energy and range, dose distribution, and so on in the longitudinal direction. At present, the methods usually used in QA measurements for particle therapy are applied in a manner of single item or off-line analysis, thereby leading to low efficiency and poor real-time performance. To aid the technique of beam performance verification in particle therapy, a software system dedicated to the method of planar fluorecence detection was developed, where C++ programming language, the interface development framework Qt5 and the computer vision library OpenCV were adopted. Lateral particle beam parameter and longitudinal range (energy) verification could be conducted with the software system, and the raw data of carbon-ion beam performance obtained in the Heavy Ion Medical Machine(HIMM) in Wuwei were employed to conduct the testing of software algorithms and functions. The successful testing demonstrated that the software system could be used in integrated fluorecence detection systems and was able to realize modular analyses of particle beam performance. Thus, the versatile software system developed in this work expands the use scope of the planar fluorecence detection technique and improves the verification efficiency of beam therapeutic performance in particle therapy significantly.
2023, 40(3): 472-477.
doi: 10.11804/NuclPhysRev.40.2022085
Abstract:
In an accelerator driven sub-critical system(ADS), it is very important to automatically control the beam intensity of the accelerator. The method for controlling the beam intensity with a proportion-integral-differential(PID) controller has been studied for the China initiative Accelerator Driven System(CiADS) facility. Firstly, in order to quickly find the global optimal parameters of the PID controller, Genetic Algorithm is used for determining the parameters of the PID controller, where the method for initializing the population in the algorithm has been improved. Secondly, a model of beam intensity is built by considering the proton beam with a Gaussian distribution of a given FWHM(Full Width at Half Maximum) at the Low Energy Beam Transport(LEBT) line of the accelerator, in order to evaluate the proposed control method with the extracted PID parameters. The simulations based on the model of beam intensity have indicated that the beam intensity varies with either the different value of FWHM or the different position of beam center. Thirdly, both the automatic and manual control functions for the beam intensity have been implemented in a distributed control system(DCS) system. In the automatic control function, the measured value of the beam intensity is sent to the DCS system and is compared with the setting value. Then, the new values of the aperture size and the rotation angle of the aperture are calculated with the PID controller and are used to adjust the beam intensity. Finally, the accuracy of the rotation angle of the aperture is measured by using the manual function in the DCS system. The measurement results show that the deviation of the angle adjustment of the aperture is less than 0.002 degree, and the adjustment accuracy of the beam intensity is 0.000 05 A.
In an accelerator driven sub-critical system(ADS), it is very important to automatically control the beam intensity of the accelerator. The method for controlling the beam intensity with a proportion-integral-differential(PID) controller has been studied for the China initiative Accelerator Driven System(CiADS) facility. Firstly, in order to quickly find the global optimal parameters of the PID controller, Genetic Algorithm is used for determining the parameters of the PID controller, where the method for initializing the population in the algorithm has been improved. Secondly, a model of beam intensity is built by considering the proton beam with a Gaussian distribution of a given FWHM(Full Width at Half Maximum) at the Low Energy Beam Transport(LEBT) line of the accelerator, in order to evaluate the proposed control method with the extracted PID parameters. The simulations based on the model of beam intensity have indicated that the beam intensity varies with either the different value of FWHM or the different position of beam center. Thirdly, both the automatic and manual control functions for the beam intensity have been implemented in a distributed control system(DCS) system. In the automatic control function, the measured value of the beam intensity is sent to the DCS system and is compared with the setting value. Then, the new values of the aperture size and the rotation angle of the aperture are calculated with the PID controller and are used to adjust the beam intensity. Finally, the accuracy of the rotation angle of the aperture is measured by using the manual function in the DCS system. The measurement results show that the deviation of the angle adjustment of the aperture is less than 0.002 degree, and the adjustment accuracy of the beam intensity is 0.000 05 A.
2023, 40(3): 478-484.
doi: 10.11804/NuclPhysRev.40.2022093
Abstract:
The Accelerator Driven subcritical System(ADS) is driven by spallation neutrons, which is generated during the proton bombarding the spallation target, to make the subcritical reactor operate stably and continuously. It has high potential to transmute the long-lived minor-actinides and produce cleaner nuclear energy. During the coupling process of the accelerator and reactor, the beam pipeline penetrates through the top cover of the reactor, and spallation neutrons and fission neutrons in the core tend to leak through the pipeline in large quantities. In order to reduce the equipment activation and reduce the personnel radiation dose received during the maintenance, it’s necessary to carry out relevant shielding design work. In the radiation shielding design of thermal spectrum reactor, the thermal neutron fluence rate is usually limited to 105 n/(cm2 · s) to reduce equipment activation and ensure maintainability. For the Accelerator Driven subcritical System, the leakage neutrons from the top cover are fast neutrons with high fluence rate. It is necessary to carry out the shielding design analysis according to an appropriate equivalent thermal neutron fluence rate. This work takes the China initiative Accelerator Driven System(CiADS) as a reference to analyze the expected radiant energy release of activated nuclides generated by the leakage neutrons, and a leakage neutron equivalent fluence rate is obtained. The applicability for this thermal neutron equivalent fluence rate is evaluated. Studies have shown that leakage neutrons with an average fluence rate of 9.292×105 n/(cm2 · s) are equivalent to thermal neutrons with a fluence rate of 105 n/(cm2 · s) in the expected radiant energy release. In the radiation shielding design, the neutron fluence rate limit outside the top cover can be conservatively taken as 8×105 n/(cm2 · s). This research work proposes a method for selecting the equivalent neutron fluence rate in the design of the ADS external activation shield, which can be used in the fast spectrum neutron shielding analysis. The thermal neutron equivalent fluence rate obtained in this paper can provide reference for the shielding design and analysis of CiADS.
The Accelerator Driven subcritical System(ADS) is driven by spallation neutrons, which is generated during the proton bombarding the spallation target, to make the subcritical reactor operate stably and continuously. It has high potential to transmute the long-lived minor-actinides and produce cleaner nuclear energy. During the coupling process of the accelerator and reactor, the beam pipeline penetrates through the top cover of the reactor, and spallation neutrons and fission neutrons in the core tend to leak through the pipeline in large quantities. In order to reduce the equipment activation and reduce the personnel radiation dose received during the maintenance, it’s necessary to carry out relevant shielding design work. In the radiation shielding design of thermal spectrum reactor, the thermal neutron fluence rate is usually limited to 105 n/(cm2 · s) to reduce equipment activation and ensure maintainability. For the Accelerator Driven subcritical System, the leakage neutrons from the top cover are fast neutrons with high fluence rate. It is necessary to carry out the shielding design analysis according to an appropriate equivalent thermal neutron fluence rate. This work takes the China initiative Accelerator Driven System(CiADS) as a reference to analyze the expected radiant energy release of activated nuclides generated by the leakage neutrons, and a leakage neutron equivalent fluence rate is obtained. The applicability for this thermal neutron equivalent fluence rate is evaluated. Studies have shown that leakage neutrons with an average fluence rate of 9.292×105 n/(cm2 · s) are equivalent to thermal neutrons with a fluence rate of 105 n/(cm2 · s) in the expected radiant energy release. In the radiation shielding design, the neutron fluence rate limit outside the top cover can be conservatively taken as 8×105 n/(cm2 · s). This research work proposes a method for selecting the equivalent neutron fluence rate in the design of the ADS external activation shield, which can be used in the fast spectrum neutron shielding analysis. The thermal neutron equivalent fluence rate obtained in this paper can provide reference for the shielding design and analysis of CiADS.
2023, 40(3): 485-491.
doi: 10.11804/NuclPhysRev.40.2022090
Abstract:
In reactor calculation, deterministic calculation software such as ANISN is fast and suitable for complex physical thermal coupling calculation tasks. But for the deterministic calculation program, the calculation accuracy is mainly restricted by the making of multi-group cross section library. In this paper, based on the Monte Carlo software OpenMC, a multi-group cross section library for deterministic programs is developed. Firstly, modeling and calculation are carried out by using OpenMC. Then, the total reaction rate, neutron fission rate, absorption reaction rate, neutron flux and high-order Legendre scattering rate are calculated by different regions and energy groups. Finally, multi-group cross section data in BUGLE-96 format is obtained by Fortran cross section conversion program. In order to verify the reliability of the cross-section library, the new cross-section library is provided to ANISN program for benchmark calculation, and the calculation results are compared with Monte Carlo program and BUGLE-96 library. The results show that the Keff and flux calculated by the cross section library based on OpenMC and the cross section conversion program are consistent with those calculated by Monte Carlo program, and the error is smaller than that calculated by BUGLE-96 library, which verifies the effectiveness of the multi-group cross section library of neutron transport SN program.
In reactor calculation, deterministic calculation software such as ANISN is fast and suitable for complex physical thermal coupling calculation tasks. But for the deterministic calculation program, the calculation accuracy is mainly restricted by the making of multi-group cross section library. In this paper, based on the Monte Carlo software OpenMC, a multi-group cross section library for deterministic programs is developed. Firstly, modeling and calculation are carried out by using OpenMC. Then, the total reaction rate, neutron fission rate, absorption reaction rate, neutron flux and high-order Legendre scattering rate are calculated by different regions and energy groups. Finally, multi-group cross section data in BUGLE-96 format is obtained by Fortran cross section conversion program. In order to verify the reliability of the cross-section library, the new cross-section library is provided to ANISN program for benchmark calculation, and the calculation results are compared with Monte Carlo program and BUGLE-96 library. The results show that the Keff and flux calculated by the cross section library based on OpenMC and the cross section conversion program are consistent with those calculated by Monte Carlo program, and the error is smaller than that calculated by BUGLE-96 library, which verifies the effectiveness of the multi-group cross section library of neutron transport SN program.
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