This study proposes a novel feature extraction approach for radionuclide identification to increase the precision of identification of the gamma-ray energy spectrum set.For easier utilization of the information contai...This study proposes a novel feature extraction approach for radionuclide identification to increase the precision of identification of the gamma-ray energy spectrum set.For easier utilization of the information contained in the spectra,the vectors of the gamma-ray energy spectra from Euclidean space,which are fingerprints of the different types of radionuclides,were mapped to matrices in the Banach space.Subsequently,to make the spectra in matrix form easier to apply to image-based deep learning frameworks,the matrices of the gamma-ray energy spectra were mapped to images in the RGB color space.A deep convolutional neural network(DCNN)model was constructed and trained on the ImageNet dataset.The mapped gamma-ray energy spectrum images were applied as inputs to the DCNN model,and the corresponding outputs of the convolution layers and fully connected layers were transferred as descriptors of the images to construct a new classification model for radionuclide identification.The transferred image descriptors consist of global and local features,where the activation vectors of fully connected layers are global features,and activations from convolution layers are local features.A series of comparative experiments between the transferred image descriptors,peak information,features extracted by the histogram of the oriented gradients(HOG),and scale-invariant feature transform(SIFT)using both synthetic and measured data were applied to 11 classical classifiers.The results demonstrate that although the gamma-ray energy spectrum images are completely unfamiliar to the DCNN model and have not been used in the pre-training process,the transferred image descriptors achieved good classification results.The global features have strong semantic information,which achieves an average accuracy of 92.76%and 94.86%on the synthetic dataset and measured dataset,respectively.The results of the statistical comparison of features demonstrate that the proposed approach outperforms the peak-searching-based method,HOG,and SIFT on the synthetic and measured datasets.展开更多
Cell voltage is a widely used signal that can be measured online from an industrial aluminum electrolysis cell.A variety of parameters for the analysis and control of industrial cells are calculated using the cell vol...Cell voltage is a widely used signal that can be measured online from an industrial aluminum electrolysis cell.A variety of parameters for the analysis and control of industrial cells are calculated using the cell voltage.In this paper,the frequency segmentation of cell voltage is used as the basis for designing filters to obtain these parameters.Based on the qualitative analysis of the cell voltage,the sub-band instantaneous energy spectrum(SIEP)is first proposed,which is then used to quantitatively represent the characteristics of the designated frequency bands of the cell voltage under various cell conditions.Ultimately,a cell condition-sensitive frequency segmentation method is given.The proposed frequency segmentation method divides the effective frequency band into the[0,0.001]Hz band of lowfrequency signals and the[0.001,0.050]Hz band of low-frequency noise,and subdivides the lowfrequency noise into the[0.001,0.010]Hz band of metal pad abnormal rolling and the[0.01,0.05]Hz band of sub-low-frequency noise.Compared with the instantaneous energy spectrum based on empirical mode decomposition,the SIEP more finely represents the law of energy change with time in any designated frequency band within the effective frequency band of the cell voltage.The proposed frequency segmentation method is more sensitive to cell condition changes and can obtain more elaborate details of online cell condition information,thus providing a more reliable and accurate online basis for cell condition monitoring and control decisions.展开更多
<strong>Purpose:</strong> The energy spectrum of a linear accelerator used for dose calculations is determined during beam commissioning by iteratively adjusting the spectrum and comparing calculated and m...<strong>Purpose:</strong> The energy spectrum of a linear accelerator used for dose calculations is determined during beam commissioning by iteratively adjusting the spectrum and comparing calculated and measured percent depth-dose curves. Direct measurement of the energy spectrum using pulse mode detectors is particularly challenging because of the high-energy, high fluence nature of these beams and limitations of the detector systems. This work implements a Compton scattering (CS) spectroscopy setup and presents detector corrections and spectral unfolding techniques to measure the spectrum of a 6 MV linear accelerator using a pulse mode detector. <strong>Methods:</strong> Spectral measurements were performed using a Varian Clinac 21EX linear accelerator and a high-purity germanium (HPGe) detector. To reduce fluence to the detector, a custom-built lead shield and a CS spectrometry setup were used. The detector was placed at CS angles of 46<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>, 89<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>, and 125<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>. At each of these locations, a detector response function was generated to account for photon interactions within the experimental geometry. Gold’s deconvolution algorithm was used to unfold the energy spectrum. The measured spectra were compared to simulated spectra, which were obtained using an experimentally benchmarked model of the Clinac 21EX in MCNP6. <strong>Results:</strong> Measurements were acquired and detector response corrections were calculated for all three CS angles. A comparison of spectra for all CS angles showed good agreement with one another. The spectra for all three angles were averaged and showed good agreement with the MCNP6 simulated spectrum, with all points above 400 keV falling within 4%, which was within the uncertainty of the measurement and statistical uncertainty. <strong>Conclusions:</strong> The measurement of the energy spectrum of a 6 MV linear accelerator using a pulse-mode detector is presented in this work. For accurate spectrum determination, great care must be taken to optimize the detector setup, determine proper corrections, and to unfold the spectrum.展开更多
A reconstruction algorithm for unfolding neutron energy spectra has been developed,based for the first time on the potential reduction interior point algorithm.This algorithm can be easily applied to neutron energy sp...A reconstruction algorithm for unfolding neutron energy spectra has been developed,based for the first time on the potential reduction interior point algorithm.This algorithm can be easily applied to neutron energy spectrum reconstruction in the recoil proton method.We transform the neutron energy spectrum unfolding problem into a typical nonnegative linear complementarity problem.The recoil proton energy spectrum and response matrix at angles of 0?and 30?are generated by the Geant4 simulation toolkit.Several different neutron energy test spectra are also employed.It is found that this unfolding algorithm is stable and provides efficient,accurate results.展开更多
Objective Neutron energy spectrum unfolding is a key technique for neutron detection.It is essentially an inversion problem.The GRAVEL algorithm has been widely used in this field,and the PRIP algorithm transforms neu...Objective Neutron energy spectrum unfolding is a key technique for neutron detection.It is essentially an inversion problem.The GRAVEL algorithm has been widely used in this field,and the PRIP algorithm transforms neutron energy spectrum unfolding into a typical nonnegative linear complementarity problem and solves it by interior point algorithm for potential reduction.Methods These two algorithms are applied to unfold several different neutron energy test spectra and actual D-T fusion neutron energy spectrum.Results and Conclusion By comparison,it can be concluded that the PRIP algorithm is highly computationally efficient and fast converging,and the GRAVEL algorithm solution results match up more with the expected results.展开更多
The prediction of reactor antineutrino spectra will play a crucial role as reactor experiments enter the precision era.The positron energy spectrum of 3.5 million antineutrino inverse beta decay reactions observed by ...The prediction of reactor antineutrino spectra will play a crucial role as reactor experiments enter the precision era.The positron energy spectrum of 3.5 million antineutrino inverse beta decay reactions observed by the Daya Bay experiment,in combination with the fission rates of fissile isotopes in the reactor,is used to extract the positron energy spectra resulting from the fission of specific isotopes.This information can be used to produce a precise,data-based prediction of the antineutrino energy spectrum in other reactor antineutrino experiments with different fission fractions than Daya Bay.The positron energy spectra are unfolded to obtain the antineutrino energy spectra by removing the contribution from detector response with the Wiener-SVD unfolding method.Consistent results are obtained with other unfolding methods.A technique to construct a data-based prediction of the reactor antineutrino energy spectrum is proposed and investigated.Given the reactor fission fractions,the technique can predict the energy spectrum to a 2%precision.In addition,we illustrate how to perform a rigorous comparison between the unfolded antineutrino spectrum and a theoretical model prediction that avoids the input model bias of the unfolding method.展开更多
Introduction The parameters of detector can play important roles in analyzing the nuclear pulses.When getting these parameters,we can establish the mathematical model of the detector output signal and then achieve amp...Introduction The parameters of detector can play important roles in analyzing the nuclear pulses.When getting these parameters,we can establish the mathematical model of the detector output signal and then achieve amplitude,time and other information of pulse simultaneously by one measurement,which can further improve the utilization of the signal.Purposes and methods In this paper,one 500 MHz digitization card was used to measure the pulses of a scintillator detector,and a bi-exponential mathematical model was used to fit the shape of the pulse,from which the decay time of the scintillator as well as the time constant of the PMT can be well obtained.Based on these parameters,the accurate energy spectrum measurement and the reconstruction of piled-up pulses are studied on.Results It was experimentally verified that this method can significantly improve the energy resolution,up to 6.31%at 661.7 keV for NaI detector(ϕ40 mm×40 mm).In addition,the piled-up pulses are well reconstructed.Conclusions For detectors with a single fluorescence decay time,a bi-exponential model can be set and used to fit the output pulse to get the parameters of the detectors.This model can be applied to obtain energy spectrum,reconstruction pulse of pile-up and so on.展开更多
Proposed is a two-dimensional(2D)spectrum analysis system for acquiring the statistical information of radioactive particles on two dimensions,i.e.energy and time.Based on pulse width modulation readout circuit,such a...Proposed is a two-dimensional(2D)spectrum analysis system for acquiring the statistical information of radioactive particles on two dimensions,i.e.energy and time.Based on pulse width modulation readout circuit,such a system with 4-channels is designed,which converts the radiation signal into a rectangular pulse signal with pulse width modulated.The pulse width,occurrence time,and pulse count of the rectangular pulses are measured simultaneously with digital counters,so that the 2D spectra on energy and time of the radioactive particles can be obtained efficiently based on bi-parameter statistical analysis.A prototype of this 2D system is tested with gamma rays from 241Am isotopes,from which both the correlated 2D spectra and the independent spectra on energy and time are obtained.The energy spectra of four channels shows all characteristic peaks of 241Am gamma rays,among which the full-energy peak at 59.5keV exhibits energy resolution of about 5-6%,suggesting a good energy resolution and channel uniformity of the system.The regression of the time spectra of the characteristic peaks can give the time constants of each characteristic peak,revealing the time characteristics of the nuclear reactions in the radiative source.展开更多
It was revealed that an average energy of special boundaries is proportional to APB energy in the alloys with the L12 superstructure. This fact proves the appearance of the GAPBs in the planes of location of special b...It was revealed that an average energy of special boundaries is proportional to APB energy in the alloys with the L12 superstructure. This fact proves the appearance of the GAPBs in the planes of location of special boundaries in coincidence sites of ordered alloys. It was determined that the more energy of special boundaries in ordered alloys, the more energy of complex stacking fault. There is a correlation between the distribution of special boundaries as a function its relative energy and ordering energy: the more ordering energy, the more degree of washed away of distribution. The correlation between average relative energy of special boundaries and ordering energy was detected: the more ordering energy, the more average energy of special boundaries. The reverse dependence between ordering energy and average number of special boundaries in grains limited by boundaries of general type was discovered.展开更多
This paper reports on the results of calculations using a Monte Carlo code (MCNP5) to study the properties of photons,electrons and photoneutrons obtained in the converted target and their transportations in x-ray rad...This paper reports on the results of calculations using a Monte Carlo code (MCNP5) to study the properties of photons,electrons and photoneutrons obtained in the converted target and their transportations in x-ray radiography.A comparison between measurements and calculations for bremsstrahlung and photoneutrons is presented.The radiographic rule and the effect of the collimator on the image are studied with the experimental model.The results provide exact parameters for the optimal design of radiographic layout and shielding systems.展开更多
Transplutonium isotopes are scarce and need to be produced by irradiation in high flux reactors.However,their production is inefficient,and optimization studies are necessary.This study analyzes the physical nature of...Transplutonium isotopes are scarce and need to be produced by irradiation in high flux reactors.However,their production is inefficient,and optimization studies are necessary.This study analyzes the physical nature of transplutonium isotope produc-tion using ^(252)Cf,^(244)Cm,^(242)Cm,and ^(238)Pu as examples.Traditional methods based on the Monte Carlo burnup calculation have the limitations of many calculations and cannot analyze the individual energy intervals in detail;thus,they cannot sup-port the refined evaluation,screening,and optimization of the irradiation schemes.After understanding the physical nature and simplifying the complexity of the production process,we propose a rapid diagnostic method for evaluating radiation schemes based on the concepts“single energy interval value(SEIV)”and“energy spectrum total value(ESTV)”.The rapid diagnostic method not only avoids tedious burnup calculations,but also provides a direction for optimization.The optimal irradiation schemes for producing ^(252)Cf,^(244)Cm,^(242)Cm,and ^(238)Pu are determined based on a rapid diagnostic method.Optimal irradiation schemes can significantly improve production efficiency.Compared with the initial scheme,the optimal scheme improved the production efficiency of ^(238)Pu by 7.41 times;^(242)Cm,11.98 times;^(244)Cm,65.20 times;and ^(252)Cf,15.08 times.Thus,a refined analysis of transplutonium isotope production is conducted and provides a theoretical basis for improving production efficiency.展开更多
AD = 1 position-dependent mass approach to constructing nonlinear quantum states for a modified Coulomb potential is used to generate Gazeau–Klauder coherent states. It appears that their energy eigenvalues are scale...AD = 1 position-dependent mass approach to constructing nonlinear quantum states for a modified Coulomb potential is used to generate Gazeau–Klauder coherent states. It appears that their energy eigenvalues are scaled down by the quantum number and the nonlinearity coefficient. We study the basic properties of these states, which are found to be undefined on the whole complex plane, and some details of their revival structure are discussed.展开更多
A class of quasi-exact solutions of the Rabi Hamiltonian,which describes a two-level atom interacting witha single-mode radiation field via a dipole interaction without the rotating-wave approximation,are obtained by ...A class of quasi-exact solutions of the Rabi Hamiltonian,which describes a two-level atom interacting witha single-mode radiation field via a dipole interaction without the rotating-wave approximation,are obtained by using awavefunction ansatz.Exact solutions for part of the spectrum are obtained when the atom-field coupling strength and thefield frequency satisfy certain relations.As an example,the lowest exact energy level and the corresponding atom-fieldentanglement at the quasi-exactly solvable point are calculated and compared to results from the Jaynes-Cummings andcounter-rotating cases of the Rabi Hamiltonian.展开更多
Investigations show that X-ray-boosted photoionization(XBP) has the following advantages for in-situ measurements of ultrahigh laser intensity I and field envelope F(t)(time t,pulse duration τL,carrier-envelope-phase...Investigations show that X-ray-boosted photoionization(XBP) has the following advantages for in-situ measurements of ultrahigh laser intensity I and field envelope F(t)(time t,pulse duration τL,carrier-envelope-phase Φ):accuracy,dynamic range,and rapidness.The calculated XBP spectra resemble inversely proportional functions of the photoelectron momentum shift.The maximum momentum p and the observable value Q(defined as a double integration of a normalized photoelectron energy spectrum,PES) linearly depend on I1/2 and τL,respectively.Φ and F(t) can be determined from the PES cut-off energy and peak positions.The measurable laser intensity can be up to and over 1018 W/cm2 by using high energy X-rays and highly charged inert gases.展开更多
The results of a study of the energy spectra of the activation of intrinsic defects of a photosensitive film made from the CdSe<sub>x</sub>S<sub>1-x</sub> solid solution depending on the condit...The results of a study of the energy spectra of the activation of intrinsic defects of a photosensitive film made from the CdSe<sub>x</sub>S<sub>1-x</sub> solid solution depending on the conditions of preparation and heat treatment in various media are presented. It is shown that at x = 0.8 cadmium vacancies create a deep level with an activation energy Е<sub>v</sub> + (0.63 ± 0.02) eV, a complex of chlorine atom with a cadmium vacancy creates a level Е<sub>v</sub> + (0.43 ± 0.02) eV, as well as the fast recombination center Еv + (0.92 ± 0.02) eV. The formation of selenium vacancies due to the introduction of chlorine and its combination with cadmium leads to the appearance of a sticking level Е<sub>c</sub> - (0.19 ± 0.02) eV. CdSe<sub>0.8</sub>S<sub>0.2</sub> films can be used to develop light emitting diodes, photo sensors, IR and visible lasers.展开更多
In the present paper,the turbulent cavitating flow generated by a Clark-Y hydrofoil is investigated by large eddy simulation(LES)combined with Zwart-Gerber-Belamri(ZGB)cavitation model.In order to shed light on the in...In the present paper,the turbulent cavitating flow generated by a Clark-Y hydrofoil is investigated by large eddy simulation(LES)combined with Zwart-Gerber-Belamri(ZGB)cavitation model.In order to shed light on the influence of cavitation on turbulent energy distribution among scales,energy spectrum obtained from the three-dimensional velocity field is firstly applied to turbulent cavitating flow.Spatial and spectral distributions of turbulent kinetic energy are studied for both non-cavitating flow and cavitating flow.Cavitation is found to have a significant effect on the original turbulent flow by inducing more large-scale turbulent structures.The energy spectrum of cloud cavitating flow also experiences a periodic evolution as cavitation develops,and a large amount of turbulent kinetic energy is found to generate as the first shedding,cutoff and second shedding of cavities happen.展开更多
Novel measurements of the neutron energy spectra of the 9Be(d,n)10B reaction with a thick beryllium target are performed using a fast neutron time-of-flight(TOF)spectrometer for the neutron emission angles θ=0°a...Novel measurements of the neutron energy spectra of the 9Be(d,n)10B reaction with a thick beryllium target are performed using a fast neutron time-of-flight(TOF)spectrometer for the neutron emission angles θ=0°and 45°,and the incident deuteron energies are 250 and 300 keV,respectively.The neutron contributions from the 9Be(d,n)10B reaction are distributed relatively independently for the ground state and the first,second,and third excited states of 10B.The branching ratios of the 9Be(d,n)10B reaction for the different excited states of 10B are obtained for the neutron emission angles θ=0°and 45°,and the incident deuteron energies are 250 and 300 keV,respectively.The branching ratio of the 9Be(d,n)10B reaction for the third excited state decreases with increase in the incident deuteron energy,and the branching ratios for the ground state and the second excited state increase with increase in the neutron emission angle.展开更多
To maintain the calmness of the harbor,rubble mound breakwaters are one of the practical measures to protect sailing and mooring waters.This paper investigates the effect of relocated rubble mound breakwaters on tranq...To maintain the calmness of the harbor,rubble mound breakwaters are one of the practical measures to protect sailing and mooring waters.This paper investigates the effect of relocated rubble mound breakwaters on tranquillity in Busan yacht range and the impact of bridge piers at the entrance of the yacht range based on physical hydraulic modeling using multi-directional random waves.It is obtained that the sufficient tranquillity can be due to securely moored yachts,owing to newly relocated rubble mound breakwaters away from piers.The experimental results also showed the distribution of the energy difference’dependence on various wave directions.The experimental findings are valuable for the design of Busan yacht marina,and are of reference to other port projects.展开更多
In this article,we study the DKP equation for the oscillator in a G?del-type space-time background.We derive the final form of this equation in a flat class of G?del-type space-time and solve it analytically,and evalu...In this article,we study the DKP equation for the oscillator in a G?del-type space-time background.We derive the final form of this equation in a flat class of G?del-type space-time and solve it analytically,and evaluate the eigenvalues and corresponding eigenfunctions,in detail.展开更多
In this paper,we investigate the relativistic quantum dynamics of spin-0 massive charged particles in a G?del-type space-time with electromagnetic interactions.We derive the radial wave equation of the Klein-Gordon eq...In this paper,we investigate the relativistic quantum dynamics of spin-0 massive charged particles in a G?del-type space-time with electromagnetic interactions.We derive the radial wave equation of the Klein-Gordon equation with an internal magnetic flux field and Coulombtype potential in the Som-Raychaudhuri space-time with cosmic string.We solve this equation and analyze the analog effect in relation to the Aharonov-Bohm effect for bound states.展开更多
基金supported by the National Defense Fundamental Research Project(No.JCKY2020404C004)Sichuan Science and Technology Program(No.22NSFSC0044).
文摘This study proposes a novel feature extraction approach for radionuclide identification to increase the precision of identification of the gamma-ray energy spectrum set.For easier utilization of the information contained in the spectra,the vectors of the gamma-ray energy spectra from Euclidean space,which are fingerprints of the different types of radionuclides,were mapped to matrices in the Banach space.Subsequently,to make the spectra in matrix form easier to apply to image-based deep learning frameworks,the matrices of the gamma-ray energy spectra were mapped to images in the RGB color space.A deep convolutional neural network(DCNN)model was constructed and trained on the ImageNet dataset.The mapped gamma-ray energy spectrum images were applied as inputs to the DCNN model,and the corresponding outputs of the convolution layers and fully connected layers were transferred as descriptors of the images to construct a new classification model for radionuclide identification.The transferred image descriptors consist of global and local features,where the activation vectors of fully connected layers are global features,and activations from convolution layers are local features.A series of comparative experiments between the transferred image descriptors,peak information,features extracted by the histogram of the oriented gradients(HOG),and scale-invariant feature transform(SIFT)using both synthetic and measured data were applied to 11 classical classifiers.The results demonstrate that although the gamma-ray energy spectrum images are completely unfamiliar to the DCNN model and have not been used in the pre-training process,the transferred image descriptors achieved good classification results.The global features have strong semantic information,which achieves an average accuracy of 92.76%and 94.86%on the synthetic dataset and measured dataset,respectively.The results of the statistical comparison of features demonstrate that the proposed approach outperforms the peak-searching-based method,HOG,and SIFT on the synthetic and measured datasets.
基金This work was supported by the Program of the National Natural Science Foundation of China(61988101,61773405,and 61751312).
文摘Cell voltage is a widely used signal that can be measured online from an industrial aluminum electrolysis cell.A variety of parameters for the analysis and control of industrial cells are calculated using the cell voltage.In this paper,the frequency segmentation of cell voltage is used as the basis for designing filters to obtain these parameters.Based on the qualitative analysis of the cell voltage,the sub-band instantaneous energy spectrum(SIEP)is first proposed,which is then used to quantitatively represent the characteristics of the designated frequency bands of the cell voltage under various cell conditions.Ultimately,a cell condition-sensitive frequency segmentation method is given.The proposed frequency segmentation method divides the effective frequency band into the[0,0.001]Hz band of lowfrequency signals and the[0.001,0.050]Hz band of low-frequency noise,and subdivides the lowfrequency noise into the[0.001,0.010]Hz band of metal pad abnormal rolling and the[0.01,0.05]Hz band of sub-low-frequency noise.Compared with the instantaneous energy spectrum based on empirical mode decomposition,the SIEP more finely represents the law of energy change with time in any designated frequency band within the effective frequency band of the cell voltage.The proposed frequency segmentation method is more sensitive to cell condition changes and can obtain more elaborate details of online cell condition information,thus providing a more reliable and accurate online basis for cell condition monitoring and control decisions.
文摘<strong>Purpose:</strong> The energy spectrum of a linear accelerator used for dose calculations is determined during beam commissioning by iteratively adjusting the spectrum and comparing calculated and measured percent depth-dose curves. Direct measurement of the energy spectrum using pulse mode detectors is particularly challenging because of the high-energy, high fluence nature of these beams and limitations of the detector systems. This work implements a Compton scattering (CS) spectroscopy setup and presents detector corrections and spectral unfolding techniques to measure the spectrum of a 6 MV linear accelerator using a pulse mode detector. <strong>Methods:</strong> Spectral measurements were performed using a Varian Clinac 21EX linear accelerator and a high-purity germanium (HPGe) detector. To reduce fluence to the detector, a custom-built lead shield and a CS spectrometry setup were used. The detector was placed at CS angles of 46<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>, 89<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>, and 125<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>. At each of these locations, a detector response function was generated to account for photon interactions within the experimental geometry. Gold’s deconvolution algorithm was used to unfold the energy spectrum. The measured spectra were compared to simulated spectra, which were obtained using an experimentally benchmarked model of the Clinac 21EX in MCNP6. <strong>Results:</strong> Measurements were acquired and detector response corrections were calculated for all three CS angles. A comparison of spectra for all CS angles showed good agreement with one another. The spectra for all three angles were averaged and showed good agreement with the MCNP6 simulated spectrum, with all points above 400 keV falling within 4%, which was within the uncertainty of the measurement and statistical uncertainty. <strong>Conclusions:</strong> The measurement of the energy spectrum of a 6 MV linear accelerator using a pulse-mode detector is presented in this work. For accurate spectrum determination, great care must be taken to optimize the detector setup, determine proper corrections, and to unfold the spectrum.
基金supported by Fundamental Research Funds for Central Universities(2016XS61)Opening Foundation of State Key Laboratory of Intense Pulsed Radiation Simulation and Effect
文摘A reconstruction algorithm for unfolding neutron energy spectra has been developed,based for the first time on the potential reduction interior point algorithm.This algorithm can be easily applied to neutron energy spectrum reconstruction in the recoil proton method.We transform the neutron energy spectrum unfolding problem into a typical nonnegative linear complementarity problem.The recoil proton energy spectrum and response matrix at angles of 0?and 30?are generated by the Geant4 simulation toolkit.Several different neutron energy test spectra are also employed.It is found that this unfolding algorithm is stable and provides efficient,accurate results.
基金Financial supports from the Fundamental Research Funds for the Central Universities(No.2016XS61)National Natural Science Foundation of China(No.1150050900)the Opening Foundation of State Key Laboratory of Intense Pulsed Radiation Simulation and Effect are gratefully acknowledged.
文摘Objective Neutron energy spectrum unfolding is a key technique for neutron detection.It is essentially an inversion problem.The GRAVEL algorithm has been widely used in this field,and the PRIP algorithm transforms neutron energy spectrum unfolding into a typical nonnegative linear complementarity problem and solves it by interior point algorithm for potential reduction.Methods These two algorithms are applied to unfold several different neutron energy test spectra and actual D-T fusion neutron energy spectrum.Results and Conclusion By comparison,it can be concluded that the PRIP algorithm is highly computationally efficient and fast converging,and the GRAVEL algorithm solution results match up more with the expected results.
基金Supported in part by the Ministry of Science and Technology of Chinathe U.S.Department of Energy,the Chinese Academy of Sciences,the CAS Center for Excellence in Particle Physics,the National Natural Science Foundation of China+3 种基金the Guangdong provincial governmentthe Shenzhen municipal government,the China General Nuclear Power Group,the Research Grants Council of the Hong Kong Special Administrative Region of China,the Ministry of Education in TWthe U.S.National Science Foundation,the Ministry of Education,Youth,and Sports of the Czech Republic,the Charles University Research Centre UNCE,the Joint Institute of Nuclear Research in Dubna,Russiathe National Commission of Scientific and Technological Research of Chile。
文摘The prediction of reactor antineutrino spectra will play a crucial role as reactor experiments enter the precision era.The positron energy spectrum of 3.5 million antineutrino inverse beta decay reactions observed by the Daya Bay experiment,in combination with the fission rates of fissile isotopes in the reactor,is used to extract the positron energy spectra resulting from the fission of specific isotopes.This information can be used to produce a precise,data-based prediction of the antineutrino energy spectrum in other reactor antineutrino experiments with different fission fractions than Daya Bay.The positron energy spectra are unfolded to obtain the antineutrino energy spectra by removing the contribution from detector response with the Wiener-SVD unfolding method.Consistent results are obtained with other unfolding methods.A technique to construct a data-based prediction of the reactor antineutrino energy spectrum is proposed and investigated.Given the reactor fission fractions,the technique can predict the energy spectrum to a 2%precision.In addition,we illustrate how to perform a rigorous comparison between the unfolded antineutrino spectrum and a theoretical model prediction that avoids the input model bias of the unfolding method.
文摘Introduction The parameters of detector can play important roles in analyzing the nuclear pulses.When getting these parameters,we can establish the mathematical model of the detector output signal and then achieve amplitude,time and other information of pulse simultaneously by one measurement,which can further improve the utilization of the signal.Purposes and methods In this paper,one 500 MHz digitization card was used to measure the pulses of a scintillator detector,and a bi-exponential mathematical model was used to fit the shape of the pulse,from which the decay time of the scintillator as well as the time constant of the PMT can be well obtained.Based on these parameters,the accurate energy spectrum measurement and the reconstruction of piled-up pulses are studied on.Results It was experimentally verified that this method can significantly improve the energy resolution,up to 6.31%at 661.7 keV for NaI detector(ϕ40 mm×40 mm).In addition,the piled-up pulses are well reconstructed.Conclusions For detectors with a single fluorescence decay time,a bi-exponential model can be set and used to fit the output pulse to get the parameters of the detectors.This model can be applied to obtain energy spectrum,reconstruction pulse of pile-up and so on.
基金supported by the National Natural Science Foundation of China(Grant No.61274048)the National Science Associated Foundation of China(Grant No.10876044)
文摘Proposed is a two-dimensional(2D)spectrum analysis system for acquiring the statistical information of radioactive particles on two dimensions,i.e.energy and time.Based on pulse width modulation readout circuit,such a system with 4-channels is designed,which converts the radiation signal into a rectangular pulse signal with pulse width modulated.The pulse width,occurrence time,and pulse count of the rectangular pulses are measured simultaneously with digital counters,so that the 2D spectra on energy and time of the radioactive particles can be obtained efficiently based on bi-parameter statistical analysis.A prototype of this 2D system is tested with gamma rays from 241Am isotopes,from which both the correlated 2D spectra and the independent spectra on energy and time are obtained.The energy spectra of four channels shows all characteristic peaks of 241Am gamma rays,among which the full-energy peak at 59.5keV exhibits energy resolution of about 5-6%,suggesting a good energy resolution and channel uniformity of the system.The regression of the time spectra of the characteristic peaks can give the time constants of each characteristic peak,revealing the time characteristics of the nuclear reactions in the radiative source.
基金B.V.Konovalova., N.A. Koneva and E.V.Kozlov acknowledge the INTAS for the partial support of this research under INTAS97-319
文摘It was revealed that an average energy of special boundaries is proportional to APB energy in the alloys with the L12 superstructure. This fact proves the appearance of the GAPBs in the planes of location of special boundaries in coincidence sites of ordered alloys. It was determined that the more energy of special boundaries in ordered alloys, the more energy of complex stacking fault. There is a correlation between the distribution of special boundaries as a function its relative energy and ordering energy: the more ordering energy, the more degree of washed away of distribution. The correlation between average relative energy of special boundaries and ordering energy was detected: the more ordering energy, the more average energy of special boundaries. The reverse dependence between ordering energy and average number of special boundaries in grains limited by boundaries of general type was discovered.
基金Project supported by the National Natural Science Foundation of China (Grant No.10576006)the Foundation of China Academy of Engineering Physics (Grant Nos.2007A01001 and 2009B0202020)
文摘This paper reports on the results of calculations using a Monte Carlo code (MCNP5) to study the properties of photons,electrons and photoneutrons obtained in the converted target and their transportations in x-ray radiography.A comparison between measurements and calculations for bremsstrahlung and photoneutrons is presented.The radiographic rule and the effect of the collimator on the image are studied with the experimental model.The results provide exact parameters for the optimal design of radiographic layout and shielding systems.
基金sponsored by Natural Science Foundation of Shanghai (NO.22ZR1431900)Science and Technology on Reactor System Design Technology Laboratory.
文摘Transplutonium isotopes are scarce and need to be produced by irradiation in high flux reactors.However,their production is inefficient,and optimization studies are necessary.This study analyzes the physical nature of transplutonium isotope produc-tion using ^(252)Cf,^(244)Cm,^(242)Cm,and ^(238)Pu as examples.Traditional methods based on the Monte Carlo burnup calculation have the limitations of many calculations and cannot analyze the individual energy intervals in detail;thus,they cannot sup-port the refined evaluation,screening,and optimization of the irradiation schemes.After understanding the physical nature and simplifying the complexity of the production process,we propose a rapid diagnostic method for evaluating radiation schemes based on the concepts“single energy interval value(SEIV)”and“energy spectrum total value(ESTV)”.The rapid diagnostic method not only avoids tedious burnup calculations,but also provides a direction for optimization.The optimal irradiation schemes for producing ^(252)Cf,^(244)Cm,^(242)Cm,and ^(238)Pu are determined based on a rapid diagnostic method.Optimal irradiation schemes can significantly improve production efficiency.Compared with the initial scheme,the optimal scheme improved the production efficiency of ^(238)Pu by 7.41 times;^(242)Cm,11.98 times;^(244)Cm,65.20 times;and ^(252)Cf,15.08 times.Thus,a refined analysis of transplutonium isotope production is conducted and provides a theoretical basis for improving production efficiency.
文摘AD = 1 position-dependent mass approach to constructing nonlinear quantum states for a modified Coulomb potential is used to generate Gazeau–Klauder coherent states. It appears that their energy eigenvalues are scaled down by the quantum number and the nonlinearity coefficient. We study the basic properties of these states, which are found to be undefined on the whole complex plane, and some details of their revival structure are discussed.
基金the U.S. National Science Foundation under Grant Nos. 0140300 and 0500291the Southeastern Universities Research Association, the National Natural Science Foundation of China under Grant Nos. 10175031+1 种基金 10575047the LSU-LNNU Joint Research Program under Grant No. C164063
文摘A class of quasi-exact solutions of the Rabi Hamiltonian,which describes a two-level atom interacting witha single-mode radiation field via a dipole interaction without the rotating-wave approximation,are obtained by using awavefunction ansatz.Exact solutions for part of the spectrum are obtained when the atom-field coupling strength and thefield frequency satisfy certain relations.As an example,the lowest exact energy level and the corresponding atom-fieldentanglement at the quasi-exactly solvable point are calculated and compared to results from the Jaynes-Cummings andcounter-rotating cases of the Rabi Hamiltonian.
基金supported by the National Natural Science Foundation of China (Grant No. 11175010)
文摘Investigations show that X-ray-boosted photoionization(XBP) has the following advantages for in-situ measurements of ultrahigh laser intensity I and field envelope F(t)(time t,pulse duration τL,carrier-envelope-phase Φ):accuracy,dynamic range,and rapidness.The calculated XBP spectra resemble inversely proportional functions of the photoelectron momentum shift.The maximum momentum p and the observable value Q(defined as a double integration of a normalized photoelectron energy spectrum,PES) linearly depend on I1/2 and τL,respectively.Φ and F(t) can be determined from the PES cut-off energy and peak positions.The measurable laser intensity can be up to and over 1018 W/cm2 by using high energy X-rays and highly charged inert gases.
文摘The results of a study of the energy spectra of the activation of intrinsic defects of a photosensitive film made from the CdSe<sub>x</sub>S<sub>1-x</sub> solid solution depending on the conditions of preparation and heat treatment in various media are presented. It is shown that at x = 0.8 cadmium vacancies create a deep level with an activation energy Е<sub>v</sub> + (0.63 ± 0.02) eV, a complex of chlorine atom with a cadmium vacancy creates a level Е<sub>v</sub> + (0.43 ± 0.02) eV, as well as the fast recombination center Еv + (0.92 ± 0.02) eV. The formation of selenium vacancies due to the introduction of chlorine and its combination with cadmium leads to the appearance of a sticking level Е<sub>c</sub> - (0.19 ± 0.02) eV. CdSe<sub>0.8</sub>S<sub>0.2</sub> films can be used to develop light emitting diodes, photo sensors, IR and visible lasers.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51822903,11772305)the Science and Technology on Water Jet Propulsion Laboratory(Grant No.61422230101162223002).
文摘In the present paper,the turbulent cavitating flow generated by a Clark-Y hydrofoil is investigated by large eddy simulation(LES)combined with Zwart-Gerber-Belamri(ZGB)cavitation model.In order to shed light on the influence of cavitation on turbulent energy distribution among scales,energy spectrum obtained from the three-dimensional velocity field is firstly applied to turbulent cavitating flow.Spatial and spectral distributions of turbulent kinetic energy are studied for both non-cavitating flow and cavitating flow.Cavitation is found to have a significant effect on the original turbulent flow by inducing more large-scale turbulent structures.The energy spectrum of cloud cavitating flow also experiences a periodic evolution as cavitation develops,and a large amount of turbulent kinetic energy is found to generate as the first shedding,cutoff and second shedding of cavities happen.
基金Supported by the National Natural Science Foundation of China(11875155,11705071.12075105)the NSFC-Nuclear Technology Innovation Joint Fund(U1867213),the NSAF(U1830102)+1 种基金the Fundamental Research Funds for the Central Universities of China(zujbky-2020-kb09)the Projet of National Defense Science and Technology Industry for Nuclear Power Technology Inovation Center(HDLCXZX-2019-HD-33)。
文摘Novel measurements of the neutron energy spectra of the 9Be(d,n)10B reaction with a thick beryllium target are performed using a fast neutron time-of-flight(TOF)spectrometer for the neutron emission angles θ=0°and 45°,and the incident deuteron energies are 250 and 300 keV,respectively.The neutron contributions from the 9Be(d,n)10B reaction are distributed relatively independently for the ground state and the first,second,and third excited states of 10B.The branching ratios of the 9Be(d,n)10B reaction for the different excited states of 10B are obtained for the neutron emission angles θ=0°and 45°,and the incident deuteron energies are 250 and 300 keV,respectively.The branching ratio of the 9Be(d,n)10B reaction for the third excited state decreases with increase in the incident deuteron energy,and the branching ratios for the ground state and the second excited state increase with increase in the neutron emission angle.
基金supported for two years by Pusan National University Research Grant BK21 PLUS.
文摘To maintain the calmness of the harbor,rubble mound breakwaters are one of the practical measures to protect sailing and mooring waters.This paper investigates the effect of relocated rubble mound breakwaters on tranquillity in Busan yacht range and the impact of bridge piers at the entrance of the yacht range based on physical hydraulic modeling using multi-directional random waves.It is obtained that the sufficient tranquillity can be due to securely moored yachts,owing to newly relocated rubble mound breakwaters away from piers.The experimental results also showed the distribution of the energy difference’dependence on various wave directions.The experimental findings are valuable for the design of Busan yacht marina,and are of reference to other port projects.
文摘In this article,we study the DKP equation for the oscillator in a G?del-type space-time background.We derive the final form of this equation in a flat class of G?del-type space-time and solve it analytically,and evaluate the eigenvalues and corresponding eigenfunctions,in detail.
文摘In this paper,we investigate the relativistic quantum dynamics of spin-0 massive charged particles in a G?del-type space-time with electromagnetic interactions.We derive the radial wave equation of the Klein-Gordon equation with an internal magnetic flux field and Coulombtype potential in the Som-Raychaudhuri space-time with cosmic string.We solve this equation and analyze the analog effect in relation to the Aharonov-Bohm effect for bound states.
