We put forward a new design of a compact beam transport system for intense laser-driven proton therapy,where instead of using conventional pulsed solenoids,our design relies on a helical coil irradiated by a nanosecon...We put forward a new design of a compact beam transport system for intense laser-driven proton therapy,where instead of using conventional pulsed solenoids,our design relies on a helical coil irradiated by a nanosecond laser pulse to generate strong magnetic fields for focusing protons.A pair of dipole magnets and apertures are employed to further filter protons with large divergences and low energies.Our numerical studies combine particle-in-cell simulations for laser-plasma interaction to generate high-energy monoenergetic proton beams,finite element analysis for evaluating the magnetic field distribution inside the coil,and MonteCarlo simulations for beam transport and energy deposition.Our results show that with this design,a spread-out Bragg peak in a range of several centimeters to a deep-seated tumor with a dose of approximately 16.5 cGy and fluctuation around 2% can be achieved.The instantaneous dose rate reaches up to 10^(9)Gy/s,holding the potential for future FLASH radiotherapy research.展开更多
All-inorganic reflective phosphor-in-glass film(PiGF) converter has garnered widespread attentions for high brightness laser-driven white lighting,while its poor color quality and low luminescence stability have been ...All-inorganic reflective phosphor-in-glass film(PiGF) converter has garnered widespread attentions for high brightness laser-driven white lighting,while its poor color quality and low luminescence stability have been inevitable roadblocks.Herein,the bicolor PiGF containing green-emitting Y3Al3.08Ga1.92O12:Ce3+(YAGG) and red-emitting CaAlSiN_(3):Eu^(2+)(CASN) phosphors bonded on Al2O3substrate was prepared for enabling high color quality laser-driven white lighting in reflective configuration.The bicolor PiGF has high quantum efficiency and good structure stability.By optimizing the CASN content,PiGF thickness and Al_(2)O_(3) content,the reflective bicolor PiGF based white laser diode(LD)displays good luminescence performance with a luminous flux of 451.5 lm and a luminous efficacy of142.3 lm/W and high color quality with a color rendering index(CRI) of 85.3 and a correlated color temperature(CCT) of 5177 K under the incident laser power of 3.15 W,and still has excellent luminescence and color stabilities(CRI and CCT) under the continuous laser excitation of 5.61 W,attributed to the good thermal conductivity and high reflectivity of Al_(2)O_(3) substrate and scattering enhancement effect of Al_(2)O_(3) particles.It can be foreseen that the reflective bicolor PiGF converter provides a promising strategy for enabling high quality laser-driven white lighting.展开更多
In the exploration of celestial bodies,such as Mars,the Moon,and asteroids,X-ray fluorescence analysis has emerged as a critical tool for elemental analysis.However,the varying selection rules and excitation sources i...In the exploration of celestial bodies,such as Mars,the Moon,and asteroids,X-ray fluorescence analysis has emerged as a critical tool for elemental analysis.However,the varying selection rules and excitation sources introduce complexity.Specifically,these discrepancies can cause variations in the intensities of the characteristic spectral lines emitted by identical elements.These variations,compounded by the minimal energy spacing between these spectral lines,pose substantial challenges for conventional silicon drift detectors(SDD),hindering their ability to accurately differentiate these lines and provide detailed insights into the material structure.To overcome this challenge,a cryogenic X-ray spectrometer based on transition-edge sensor(TES)detector arrays is required to achieve precise measurements.This study measured and analyzed the K-edge characteristic lines of copper and the diverse L-edge characteristic lines of tungsten using a comparative analysis of the electron and X-ray excitation processes.For the electron excitation experiments,copper and tungsten targets were employed as X-ray sources,as they emit distinctive X-ray spectra upon electron-beam bombardment.In the photon excitation experiments,a molybdenum target was used to produce a continuous spectrum with the prominent Mo Kαlines to emit pure copper and tungsten samples.TES detectors were used for the comparative spectroscopic analysis.The initial comparison revealed no substantial differences in the Kαand Kβlines of copper across different excitation sources.Similarly,the Lαlines of tungsten exhibited uniformity under different excitation sources.However,this investigation revealed pronounced differences within the Lβline series.The study found that XRF spectra preferentially excite outer-shell electrons,in contrast to intrinsic spectra,owing to different photon and electron interaction mechanisms.Photon interactions are selection-ruledependent and involve a single electron,whereas electron interactions can involve multiple electrons without such limitations.This leads to varied excitation transitions,as evidenced in the observed Lβline series.展开更多
β-ray-induced X-ray spectroscopy(BIXS)is a promising technique for tritium analysis that offers several unique advantages,including substantial detection depth,nondestructive testing capabilities,and ease of operatio...β-ray-induced X-ray spectroscopy(BIXS)is a promising technique for tritium analysis that offers several unique advantages,including substantial detection depth,nondestructive testing capabilities,and ease of operation.For thin solid tritium-containing samples with substrates,the currently used BIXS analysis method can measure the tritium depth profile and content when the sample thickness is known.In this study,a backpropagation(BP)neural network algorithm was used to predict the tritium content and thickness of a thin solid tritium-containing sample with substrates and a uniformly distributed tritium profile.A semi-analytical method was used to generate datasets for training and testing the BP neural network.A dataset ofβ-decay X-ray spectra from 420 tritium-containing zirconium models with different known thicknesses and tritium-tozirconium ratios was used as the input data.The corresponding zirconium thicknesses and tritium-to-zirconium ratios served as the output for training and testing the BP neural network.The mean relative errors(MREs)of the zirconium thickness in the training and test datasets were 0.56%and 0.42%,respectively,whereas the MREs of the tritium-to-zirconium ratio were 0.59%and 0.38%,respectively.Furthermore,the trained BP neural network demonstrates excellent predictive capability across various levels of statistical uncertainty.For the experimentalβ-decay X-ray spectra of two tritium-containing samples,the predicted zirconium thicknesses and tritium-to-zirconium ratios showed good agreement with the results obtained through the elastic backscattering spectrometry(EBS).展开更多
The energetic bremsstrahlung photons up to 100 MeV produced in heavy ion collisions can be used as a sensitive probe for short-range correlation in atomic nuclei. The energy of the γ-rays can be measured by collectin...The energetic bremsstrahlung photons up to 100 MeV produced in heavy ion collisions can be used as a sensitive probe for short-range correlation in atomic nuclei. The energy of the γ-rays can be measured by collecting the Čerenkov light in the medium induced by the fast electrons generated in the Compton scattering or electromagnetic shower of the incident γray. Two types of detectors based on pure water and lead glass as sensitive materials were designed for this purpose. The γresponse and optical photon propagation in the detectors were simulated based on electromagnetic and optical processes in Geant4. The inherent energy resolutions of 0.022(4) + 0.51(2)∕E^(1/2)_(γ) for water and 0.0026(3) + 0.446(3)∕E^(1/2)_(γ) for lead glass were obtained. The geometry sizes of the lead glass and water were optimized to 30 cm × 30 cm × 30 cm and 60 cm × 60 cm ×120 cm, respectively, to detect high-energy γ-rays at 160 MeV. The Hough transform method was applied to reconstruct the direction of the incident γ-rays, providing the ability to experimentally distinguish the high-energy γ-rays produced in the reactions on the target from random background cosmic-ray muons.展开更多
The poloidal magnetic field( B_(p)) plays a critical role in plasma equilibrium, confinement and transport of magnetic confinement devices. Multiple diagnostic methods are needed to complement each other to obtain a m...The poloidal magnetic field( B_(p)) plays a critical role in plasma equilibrium, confinement and transport of magnetic confinement devices. Multiple diagnostic methods are needed to complement each other to obtain a more accurate B_(p) profile. Recently, the laser-driven ion-beam trace probe(LITP) has been proposed as a promising tool for diagnosing B_(p) and radial electric field( E_(r)) profiles in tokamaks [Yang X Y et al 2014 Rev. Sci. Instrum. 85 11E429]. The spherical tokamak(ST) is a promising compact device with high plasma beta and naturally large elongation. However, when applying LITP to diagnosing B_(p) in STs, the larger B_(p) invalidates the linear reconstruction relationship for conventional tokamaks, necessitating the development of a nonlinear reconstruction principle tailored to STs. This novel approach employs an iterative reconstruction method based on Newton's method to solve the nonlinear equation. Subsequently,a simulation model to reconstruct the B_(p) profile of STs is developed and the experimental setup of LITP is designed for EXL-50, a middle-sized ST. Simulation results of the reconstruction show that the relative errors of B_(p) reconstruction are mostly below 5%. Moreover, even with 5 mm measurement error on beam traces or 1 cm flux surface shape error, the average relative error of reconstruction remains below 15%, initially demonstrating the robustness of LITP in diagnosing B_(p) profiles in STs.展开更多
Laser-accelerated high-flux-intensity heavy-ion beams are important for new types of accelerators.A particle-in-cell program(Smilei) is employed to simulate the entire process of Station of Extreme Light(SEL) 100 PW l...Laser-accelerated high-flux-intensity heavy-ion beams are important for new types of accelerators.A particle-in-cell program(Smilei) is employed to simulate the entire process of Station of Extreme Light(SEL) 100 PW laser-accelerated heavy particles using different nanoscale short targets with a thickness of 100 nm Cr, Fe, Ag, Ta, Au, Pb, Th and U, as well as 200 nm thick Al and Ca. An obvious stratification is observed in the simulation. The layering phenomenon is a hybrid acceleration mechanism reflecting target normal sheath acceleration and radiation pressure acceleration, and this phenomenon is understood from the simulated energy spectrum,ionization and spatial electric field distribution. According to the stratification, it is suggested that high-quality heavy-ion beams could be expected for fusion reactions to synthesize superheavy nuclei. Two plasma clusters in the stratification are observed simultaneously, which suggest new techniques for plasma experiments as well as thinner metal targets in the precision machining process.展开更多
To detect radioactive substances with low activity levels,an anticoincidence detector and a high-purity germanium(HPGe)detector are typically used simultaneously to suppress Compton scattering background,thereby resul...To detect radioactive substances with low activity levels,an anticoincidence detector and a high-purity germanium(HPGe)detector are typically used simultaneously to suppress Compton scattering background,thereby resulting in an extremely low detection limit and improving the measurement accuracy.However,the complex and expensive hardware required does not facilitate the application or promotion of this method.Thus,a method is proposed in this study to discriminate the digital waveform of pulse signals output using an HPGe detector,whereby Compton scattering background is suppressed and a low minimum detectable activity(MDA)is achieved without using an expensive and complex anticoincidence detector and device.The electric-field-strength and energy-deposition distributions of the detector are simulated to determine the relationship between pulse shape and energy-deposition location,as well as the characteristics of energy-deposition distributions for fulland partial-energy deposition events.This relationship is used to develop a pulse-shape-discrimination algorithm based on an artificial neural network for pulse-feature identification.To accurately determine the relationship between the deposited energy of gamma(γ)rays in the detector and the deposition location,we extract four shape parameters from the pulse signals output by the detector.Machine learning is used to input the four shape parameters into the detector.Subsequently,the pulse signals are identified and classified to discriminate between partial-and full-energy deposition events.Some partial-energy deposition events are removed to suppress Compton scattering.The proposed method effectively decreases the MDA of an HPGeγ-energy dispersive spectrometer.Test results show that the Compton suppression factors for energy spectra obtained from measurements on ^(152)Eu,^(137)Cs,and ^(60)Co radioactive sources are 1.13(344 keV),1.11(662 keV),and 1.08(1332 keV),respectively,and that the corresponding MDAs are 1.4%,5.3%,and 21.6%lower,respectively.展开更多
[Objective] To study the effect of 60Co γ-rays irradiation on Botrytis cinerea biocontrol strains—Bacillus subtilis NCD-2. [Method] NCD-2 cells were irradiated at different doses of γ-rays from 100 to 2 000 Gy. The...[Objective] To study the effect of 60Co γ-rays irradiation on Botrytis cinerea biocontrol strains—Bacillus subtilis NCD-2. [Method] NCD-2 cells were irradiated at different doses of γ-rays from 100 to 2 000 Gy. The strains were screened by plate confrontation method and Oxford cup diffusion. [Result] The curves of the relationship of irradiation dose and mutation and lethal rate were obtained. The results showed that lethal rate increased with the increasing of irradiation dose. The lethal rate of 1 000 Gy irradiation dose reached 99.50%. The mutation rate increased below 500 Gy and decreased above 500 Gy. The highest mutation rate occurred when the irradiation dose was between 400 and 700 Gy, and the average mutation rate was above 15%. The optimal irradiation dose was 500 Gy, when the average mutation rate was 26.51% and lethal rate was 77.71%. [Conclusion] This study provided references for γ-rays irradiation mutation of Bacillus subtilis.展开更多
[Objective] This study was to explore the mutagenic effect of 60Co γ-ray on Solanum tuberosum chromosomes.[Method] The 60Co γ-ray at different irradiation doses was applied to treat the minitubers of potato variety ...[Objective] This study was to explore the mutagenic effect of 60Co γ-ray on Solanum tuberosum chromosomes.[Method] The 60Co γ-ray at different irradiation doses was applied to treat the minitubers of potato variety ＇Favorita＇,and the genomic mutations in VM1 and VM2 gene rations in treatments with different doses were analyzed by SRAP markers.[Resalt] Thirty pairs of SRAP primers out of 88 pairs exhibited polymorphism with a rate of 34.1％ in the bulked selection of VM1 generation.A total of 225 bands were obtained,of which 64 were polymorphic with a rate of 28.4％.The polymorphism was reflected in the forms of deleted bands and added bands.Based on the result of the bulked selection of VM1 generation,25 primers with polymorphism were selected to scan VM2 generation.Five primers performed poorly,and nine of the rest 20 pairs revealed polymorphism and obtained nine polymorphic bands,of which only four bands were detected in VM1 generation and the other five ones were newly deleted bands.Only 9.8％ of the bands detected in VM1 generation were obtained in VM2 generation.Eventually,nine stable and dear polymorphic bands were recovered and cloned,and DNA sequences of six bands of them were acquired by sequencing.According to the comparative analysis,five fragments sequences were similar to potato chromosome with a similarity rate of 77％-89％,three of them located at the resistance gene cluster; another one fragment had a similarity of 93％ with some regions of the No.5 chromosome in tomato.[Conclusion] 60Co γ-ray irradiation can cause mutation of genomic DNA in potato;there is no significant correlation between the number of polymorphic bands and the irradiation dose; potymorphic bands are characterized by a larger number of deleted bands than that of the added ones.展开更多
[Objective] This study aimed to investigate the mutagenic effect of 60 Co γ-rays irradiation on turf characteristics of Buchloe dactyloides （Nutt.） Engelm. [Method] Buffalo grass were irradiated with 60 Co γ-rays ...[Objective] This study aimed to investigate the mutagenic effect of 60 Co γ-rays irradiation on turf characteristics of Buchloe dactyloides （Nutt.） Engelm. [Method] Buffalo grass were irradiated with 60 Co γ-rays at five different radiation intensities （1 200, 1 400, 1 600, 1 800, 2 000 Gy） to determine the related turf characteristics and analyze the mutagenic effect of 60 Co γ-rays at different radiation intensities on buffalo grass. [Result] Germination rates of buffalo grass irradiated by different radiation intensities of 60 Co γ-rays varied inconsistently, and the root length and bud length were shorter than the control; compared with the control, the height of irradiated seedlings was significantly reduced, and the number of tillers, plant height, leaf length and leaf blade width were smaller than the control; however, the stolon length, stolon diameter and number of stolon nods had no significant difference compared with the control. [Conclusion] This study laid foundation for determining the appropriate radiation intensity of 60 Co γ-rays and selecting useful mutants of buffalo grass.展开更多
We report a γ-ray irradiation reduction method to prepare MnO/reduced graphene oxide （rCO） nanocomposite for the anode of lithium ion batteries. γ-Ray irradiation provides a clean way to generate homogeneously dis...We report a γ-ray irradiation reduction method to prepare MnO/reduced graphene oxide （rCO） nanocomposite for the anode of lithium ion batteries. γ-Ray irradiation provides a clean way to generate homogeneously dispersed MnO nanoparticles with finely tuned size on rGO surface without the use of surfactant. The MnO/rGO composite enables a fully charge/discharge in 2 min to gain a reversible specific capacity of 546 （mA-h）/g which is 45 higher than the theoretical value of commercial graphite anode.展开更多
Inγ-ray imaging,localization of theγ-ray interaction in the scintillator is critical.Convolutional neural network(CNN)techniques are highly promising for improvingγ-ray localization.Our study evaluated the generali...Inγ-ray imaging,localization of theγ-ray interaction in the scintillator is critical.Convolutional neural network(CNN)techniques are highly promising for improvingγ-ray localization.Our study evaluated the generalization capabilities of a CNN localization model with respect to theγ-ray energy and thickness of the crystal.The model maintained a high positional linearity(PL)and spatial resolution for ray energies between 59 and 1460 keV.The PL at the incident surface of the detector was 0.99,and the resolution of the central incident point source ranged between 0.52 and 1.19 mm.In modified uniform redundant array(MURA)imaging systems using a thick crystal,the CNNγ-ray localization model significantly improved the useful field-of-view(UFOV)from 60.32 to 93.44%compared to the classical centroid localization methods.Additionally,the signal-to-noise ratio of the reconstructed images increased from 0.95 to 5.63.展开更多
Volumetric fraction distribution measurement is a constituent part of process tomography system in oil-water-gas multiphase flow. With the technological development of nuclear radial inspection, dual-energy γ-ray tec...Volumetric fraction distribution measurement is a constituent part of process tomography system in oil-water-gas multiphase flow. With the technological development of nuclear radial inspection, dual-energy γ-ray techniques make it possible to investigate the concentration of the different components on the cross-section of oil-water-gas multiphase pipe-flow. The dual-energy gamma-ray technique is based on materials attenuation coefficients measurement comprised of two radioactive isotopes of 241Am and 241Cs which have emission energies at 59.5 keV and 662 keV in this project. Nuclear instruments and data acquisition system were designed to measure the material’s attenuation dose rate and a number of static tests were conducted at the Multiphase Laboratory, Institute of Mechanics, Chinese Academy of Sciences. Three phases of oil-water-gas media were inves- tigated for their possible use to simulate different media volumetric fraction distributions in experimental vessels. Attenuation intensities were measured, and the arithmetic of linear attenuation coefficients and the equations of volumetric fractions were studied. Investigation of an unexpected measurement error from attenuation equations revealed that a modified arithmetic was involved and finally the system achieved acceptable accuracy in experimental research.展开更多
It is of particular interest to investigate nuclear fusion reactions generated by high-intensity lasers in plasma environments that are similar to real astrophysical conditions.We have experimentally investigated2H(d,...It is of particular interest to investigate nuclear fusion reactions generated by high-intensity lasers in plasma environments that are similar to real astrophysical conditions.We have experimentally investigated2H(d,p)3H,one of the most crucial reactions in big bang nucleosynthesis models,at the Shenguang-Ⅱlaser facility.In this work,we present a new calibration of CR-39 solidstate track detectors,which are widely employed as the main diagnostics in this type of fusion reaction experiment.We measure the dependence of the track diameter on the proton energy.It is found that the track diameters of protons with different energies are likely to be identical.We propose that in this case,the energy of the reaction products can be obtained by considering both the diameters and gray levels of these tracks.The present results would be very helpful for analyzing the2 H(d,p)3H reaction products recorded with the same batch of CR-39 solid-state track detectors.展开更多
For a characteristic c-ray with interlaced overlap peak, and the case where its reliable and credible net count cannot be obtained using the current high-purity germanium(HPGe) multichannel γ-ray spectrum software, t...For a characteristic c-ray with interlaced overlap peak, and the case where its reliable and credible net count cannot be obtained using the current high-purity germanium(HPGe) multichannel γ-ray spectrum software, two new methods are proposed herein to obtain the γ-ray net peak count from the interlaced overlap peak in the HPGe cray spectrometer system, of which one is the symmetric conversion method based on Gaussian distribution and the other is where the energy average value of two close γ-rays is regarded as the γ-ray energy. The experimental results indicate that the two methods mentioned above are reliable and credible. This study is significant for the development of better γ-ray spectrum processing software for measuring complex γ-ray spectra concerning the nuclear reaction cross section, neutron activation analysis, and analysis of transuranium elements, using an HPGe detector.展开更多
AIM:To evaluate the survival outcomes of patients with lacrimal gland adenoid cystic carcinoma who underwent eye-sparing surgery combined with ^(125I)seed implantation radiotherapy or local externalγ-ray radiotherapy...AIM:To evaluate the survival outcomes of patients with lacrimal gland adenoid cystic carcinoma who underwent eye-sparing surgery combined with ^(125I)seed implantation radiotherapy or local externalγ-ray radiotherapy.METHODS:In this retrospective comparative case series,the clinical records of 27 primary and 8 recurrent patients were reviewed.Univariate and multivariate analyses were used to identify risk factors associated with distant metastasis(DM),and the overall survival(OS)after the initial surgery was analyzed.RESULTS:The median follow-up after radiotherapy was 36 mo(range 6-120 mo).At the last follow-up after radiotherapy,26(74.3%)patients had no evidence of disease,7(20%)patients had DM,2(5.9%)patients died of DM,and 1 patient with DM was lost to follow-up.Univariate analyses showed that duration of symptoms,bone destruction,T stage classification,and wide excision surgery were risk factors influencing DM(P<0.05).The 5-year and 10-year OS rates after the initial surgery were 95.8%and 79.9%,respectively.The 5-year DM-free survival and disease-free survival rates after radiotherapy were 66.4%and 52.7%,respectively.CONCLUSION:^(125I)seed radiotherapy and local externalγ-ray radiotherapy may have similar therapeutic effects in preventing DM.Patients with T1/T2 stage disease have a better prognosis than those with T3/T4 stage disease.展开更多
By using a new method, ^60Co γ-ray irradiation, Fe3O4 magnetic nano-particles were successfully synthesized at room temperature under ambient pressure. The structure, morphology and magnetic properties of these nanop...By using a new method, ^60Co γ-ray irradiation, Fe3O4 magnetic nano-particles were successfully synthesized at room temperature under ambient pressure. The structure, morphology and magnetic properties of these nanoparticles were characterized by X-ray diffraction （XRD）, transmission electron microscope （TEM） and vibrating sample magnetometer （VSM）, respectively. The radiation formation mechanism was also discussed. The results show that the absorbed dose can greatly influence the structure, morphology and magnetic properties of the products. XRD and TEM studies show that the product prepared by γ-ray irradiation （10 kGy） is pure FesO4 phase and the mean diameter of these nano-particles is about 21 nm. The Fe3O4 nano-particles synthesized by γ-ray irradiation （10 kGy） are mainly in small cubic shape and the size uniformity of these particles is good.展开更多
基金supported by the National Key R&D Program of China(Nos.2022YFA1603200 and 2022YFA1603201)National Natural Science Foundation of China(Nos.12135001,11921006,12475243 and 11825502)+1 种基金Strategic Priority Research Program of CAS(No.XDA25050900)support from the National Natural Science Funds for Distinguished Young Scholar(No.11825502)。
文摘We put forward a new design of a compact beam transport system for intense laser-driven proton therapy,where instead of using conventional pulsed solenoids,our design relies on a helical coil irradiated by a nanosecond laser pulse to generate strong magnetic fields for focusing protons.A pair of dipole magnets and apertures are employed to further filter protons with large divergences and low energies.Our numerical studies combine particle-in-cell simulations for laser-plasma interaction to generate high-energy monoenergetic proton beams,finite element analysis for evaluating the magnetic field distribution inside the coil,and MonteCarlo simulations for beam transport and energy deposition.Our results show that with this design,a spread-out Bragg peak in a range of several centimeters to a deep-seated tumor with a dose of approximately 16.5 cGy and fluctuation around 2% can be achieved.The instantaneous dose rate reaches up to 10^(9)Gy/s,holding the potential for future FLASH radiotherapy research.
基金Project supported by the Science and Technology Project of Shenzhen City (JSGG20210802154213040)the Guangdong Basic and Applied Basic Research Foundation (2024A1515010001)the Shenzhen Postdoctoral Research Funding Project。
文摘All-inorganic reflective phosphor-in-glass film(PiGF) converter has garnered widespread attentions for high brightness laser-driven white lighting,while its poor color quality and low luminescence stability have been inevitable roadblocks.Herein,the bicolor PiGF containing green-emitting Y3Al3.08Ga1.92O12:Ce3+(YAGG) and red-emitting CaAlSiN_(3):Eu^(2+)(CASN) phosphors bonded on Al2O3substrate was prepared for enabling high color quality laser-driven white lighting in reflective configuration.The bicolor PiGF has high quantum efficiency and good structure stability.By optimizing the CASN content,PiGF thickness and Al_(2)O_(3) content,the reflective bicolor PiGF based white laser diode(LD)displays good luminescence performance with a luminous flux of 451.5 lm and a luminous efficacy of142.3 lm/W and high color quality with a color rendering index(CRI) of 85.3 and a correlated color temperature(CCT) of 5177 K under the incident laser power of 3.15 W,and still has excellent luminescence and color stabilities(CRI and CCT) under the continuous laser excitation of 5.61 W,attributed to the good thermal conductivity and high reflectivity of Al_(2)O_(3) substrate and scattering enhancement effect of Al_(2)O_(3) particles.It can be foreseen that the reflective bicolor PiGF converter provides a promising strategy for enabling high quality laser-driven white lighting.
基金supported by the National Key R&D Program of China(No.2022YFF0608303)the National Major Scientific Research Instrument Development Project(No.11927805)+4 种基金the NSFC Young Scientists Fund(No.12005134)the Shanghai-XFEL Beamline Project(SBP)(No.31011505505885920161A2101001)the Shanghai Municipal Science and Technology Major Project(No.2017SHZDZX02)the Open Fund of the Key Laboratory for Particle Astrophysics and CosmologyMinistry of Education of China。
文摘In the exploration of celestial bodies,such as Mars,the Moon,and asteroids,X-ray fluorescence analysis has emerged as a critical tool for elemental analysis.However,the varying selection rules and excitation sources introduce complexity.Specifically,these discrepancies can cause variations in the intensities of the characteristic spectral lines emitted by identical elements.These variations,compounded by the minimal energy spacing between these spectral lines,pose substantial challenges for conventional silicon drift detectors(SDD),hindering their ability to accurately differentiate these lines and provide detailed insights into the material structure.To overcome this challenge,a cryogenic X-ray spectrometer based on transition-edge sensor(TES)detector arrays is required to achieve precise measurements.This study measured and analyzed the K-edge characteristic lines of copper and the diverse L-edge characteristic lines of tungsten using a comparative analysis of the electron and X-ray excitation processes.For the electron excitation experiments,copper and tungsten targets were employed as X-ray sources,as they emit distinctive X-ray spectra upon electron-beam bombardment.In the photon excitation experiments,a molybdenum target was used to produce a continuous spectrum with the prominent Mo Kαlines to emit pure copper and tungsten samples.TES detectors were used for the comparative spectroscopic analysis.The initial comparison revealed no substantial differences in the Kαand Kβlines of copper across different excitation sources.Similarly,the Lαlines of tungsten exhibited uniformity under different excitation sources.However,this investigation revealed pronounced differences within the Lβline series.The study found that XRF spectra preferentially excite outer-shell electrons,in contrast to intrinsic spectra,owing to different photon and electron interaction mechanisms.Photon interactions are selection-ruledependent and involve a single electron,whereas electron interactions can involve multiple electrons without such limitations.This leads to varied excitation transitions,as evidenced in the observed Lβline series.
基金supported by the National Natural Science Foundation of China(No.12175158)the Institute of Nuclear Physics and Chemistry,China Academy of Engineering Physics(No.HG2022022)。
文摘β-ray-induced X-ray spectroscopy(BIXS)is a promising technique for tritium analysis that offers several unique advantages,including substantial detection depth,nondestructive testing capabilities,and ease of operation.For thin solid tritium-containing samples with substrates,the currently used BIXS analysis method can measure the tritium depth profile and content when the sample thickness is known.In this study,a backpropagation(BP)neural network algorithm was used to predict the tritium content and thickness of a thin solid tritium-containing sample with substrates and a uniformly distributed tritium profile.A semi-analytical method was used to generate datasets for training and testing the BP neural network.A dataset ofβ-decay X-ray spectra from 420 tritium-containing zirconium models with different known thicknesses and tritium-tozirconium ratios was used as the input data.The corresponding zirconium thicknesses and tritium-to-zirconium ratios served as the output for training and testing the BP neural network.The mean relative errors(MREs)of the zirconium thickness in the training and test datasets were 0.56%and 0.42%,respectively,whereas the MREs of the tritium-to-zirconium ratio were 0.59%and 0.38%,respectively.Furthermore,the trained BP neural network demonstrates excellent predictive capability across various levels of statistical uncertainty.For the experimentalβ-decay X-ray spectra of two tritium-containing samples,the predicted zirconium thicknesses and tritium-to-zirconium ratios showed good agreement with the results obtained through the elastic backscattering spectrometry(EBS).
基金This work was supported by the Ministry of Science and Technology(No.2020YFE0202001)by the National Natural Science Foundation of China(Nos.11961141004 and 12205160)Tsinghua University Initiative Scientific Research Program.
文摘The energetic bremsstrahlung photons up to 100 MeV produced in heavy ion collisions can be used as a sensitive probe for short-range correlation in atomic nuclei. The energy of the γ-rays can be measured by collecting the Čerenkov light in the medium induced by the fast electrons generated in the Compton scattering or electromagnetic shower of the incident γray. Two types of detectors based on pure water and lead glass as sensitive materials were designed for this purpose. The γresponse and optical photon propagation in the detectors were simulated based on electromagnetic and optical processes in Geant4. The inherent energy resolutions of 0.022(4) + 0.51(2)∕E^(1/2)_(γ) for water and 0.0026(3) + 0.446(3)∕E^(1/2)_(γ) for lead glass were obtained. The geometry sizes of the lead glass and water were optimized to 30 cm × 30 cm × 30 cm and 60 cm × 60 cm ×120 cm, respectively, to detect high-energy γ-rays at 160 MeV. The Hough transform method was applied to reconstruct the direction of the incident γ-rays, providing the ability to experimentally distinguish the high-energy γ-rays produced in the reactions on the target from random background cosmic-ray muons.
基金the support of National Key Research and Development Program of China (No. 2022YFA1604600)State Key Laboratory of Advanced Electromagnetic Technology。
文摘The poloidal magnetic field( B_(p)) plays a critical role in plasma equilibrium, confinement and transport of magnetic confinement devices. Multiple diagnostic methods are needed to complement each other to obtain a more accurate B_(p) profile. Recently, the laser-driven ion-beam trace probe(LITP) has been proposed as a promising tool for diagnosing B_(p) and radial electric field( E_(r)) profiles in tokamaks [Yang X Y et al 2014 Rev. Sci. Instrum. 85 11E429]. The spherical tokamak(ST) is a promising compact device with high plasma beta and naturally large elongation. However, when applying LITP to diagnosing B_(p) in STs, the larger B_(p) invalidates the linear reconstruction relationship for conventional tokamaks, necessitating the development of a nonlinear reconstruction principle tailored to STs. This novel approach employs an iterative reconstruction method based on Newton's method to solve the nonlinear equation. Subsequently,a simulation model to reconstruct the B_(p) profile of STs is developed and the experimental setup of LITP is designed for EXL-50, a middle-sized ST. Simulation results of the reconstruction show that the relative errors of B_(p) reconstruction are mostly below 5%. Moreover, even with 5 mm measurement error on beam traces or 1 cm flux surface shape error, the average relative error of reconstruction remains below 15%, initially demonstrating the robustness of LITP in diagnosing B_(p) profiles in STs.
基金support from the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB34030000)the National Key R & D Program of China (No.2022YFA1602404)+2 种基金National Natural Science Foundation of China (No. U1832129)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (No.2017309)the Program for Innovative Research Team (in Science and Technology) in University of Henan Province of China (No.21IRTSTHN011)。
文摘Laser-accelerated high-flux-intensity heavy-ion beams are important for new types of accelerators.A particle-in-cell program(Smilei) is employed to simulate the entire process of Station of Extreme Light(SEL) 100 PW laser-accelerated heavy particles using different nanoscale short targets with a thickness of 100 nm Cr, Fe, Ag, Ta, Au, Pb, Th and U, as well as 200 nm thick Al and Ca. An obvious stratification is observed in the simulation. The layering phenomenon is a hybrid acceleration mechanism reflecting target normal sheath acceleration and radiation pressure acceleration, and this phenomenon is understood from the simulated energy spectrum,ionization and spatial electric field distribution. According to the stratification, it is suggested that high-quality heavy-ion beams could be expected for fusion reactions to synthesize superheavy nuclei. Two plasma clusters in the stratification are observed simultaneously, which suggest new techniques for plasma experiments as well as thinner metal targets in the precision machining process.
基金This work was supported by the National Key R&D Program of China(Nos.2022YFF0709503,2022YFB1902700,2017YFC0602101)the Key Research and Development Program of Sichuan province(No.2023YFG0347)the Key Research and Development Program of Sichuan province(No.2020ZDZX0007).
文摘To detect radioactive substances with low activity levels,an anticoincidence detector and a high-purity germanium(HPGe)detector are typically used simultaneously to suppress Compton scattering background,thereby resulting in an extremely low detection limit and improving the measurement accuracy.However,the complex and expensive hardware required does not facilitate the application or promotion of this method.Thus,a method is proposed in this study to discriminate the digital waveform of pulse signals output using an HPGe detector,whereby Compton scattering background is suppressed and a low minimum detectable activity(MDA)is achieved without using an expensive and complex anticoincidence detector and device.The electric-field-strength and energy-deposition distributions of the detector are simulated to determine the relationship between pulse shape and energy-deposition location,as well as the characteristics of energy-deposition distributions for fulland partial-energy deposition events.This relationship is used to develop a pulse-shape-discrimination algorithm based on an artificial neural network for pulse-feature identification.To accurately determine the relationship between the deposited energy of gamma(γ)rays in the detector and the deposition location,we extract four shape parameters from the pulse signals output by the detector.Machine learning is used to input the four shape parameters into the detector.Subsequently,the pulse signals are identified and classified to discriminate between partial-and full-energy deposition events.Some partial-energy deposition events are removed to suppress Compton scattering.The proposed method effectively decreases the MDA of an HPGeγ-energy dispersive spectrometer.Test results show that the Compton suppression factors for energy spectra obtained from measurements on ^(152)Eu,^(137)Cs,and ^(60)Co radioactive sources are 1.13(344 keV),1.11(662 keV),and 1.08(1332 keV),respectively,and that the corresponding MDAs are 1.4%,5.3%,and 21.6%lower,respectively.
基金Supported by Being Science and Technology Institute "Bud Plan" Project(No.022)~~
文摘[Objective] To study the effect of 60Co γ-rays irradiation on Botrytis cinerea biocontrol strains—Bacillus subtilis NCD-2. [Method] NCD-2 cells were irradiated at different doses of γ-rays from 100 to 2 000 Gy. The strains were screened by plate confrontation method and Oxford cup diffusion. [Result] The curves of the relationship of irradiation dose and mutation and lethal rate were obtained. The results showed that lethal rate increased with the increasing of irradiation dose. The lethal rate of 1 000 Gy irradiation dose reached 99.50%. The mutation rate increased below 500 Gy and decreased above 500 Gy. The highest mutation rate occurred when the irradiation dose was between 400 and 700 Gy, and the average mutation rate was above 15%. The optimal irradiation dose was 500 Gy, when the average mutation rate was 26.51% and lethal rate was 77.71%. [Conclusion] This study provided references for γ-rays irradiation mutation of Bacillus subtilis.
文摘[Objective] This study was to explore the mutagenic effect of 60Co γ-ray on Solanum tuberosum chromosomes.[Method] The 60Co γ-ray at different irradiation doses was applied to treat the minitubers of potato variety ＇Favorita＇,and the genomic mutations in VM1 and VM2 gene rations in treatments with different doses were analyzed by SRAP markers.[Resalt] Thirty pairs of SRAP primers out of 88 pairs exhibited polymorphism with a rate of 34.1％ in the bulked selection of VM1 generation.A total of 225 bands were obtained,of which 64 were polymorphic with a rate of 28.4％.The polymorphism was reflected in the forms of deleted bands and added bands.Based on the result of the bulked selection of VM1 generation,25 primers with polymorphism were selected to scan VM2 generation.Five primers performed poorly,and nine of the rest 20 pairs revealed polymorphism and obtained nine polymorphic bands,of which only four bands were detected in VM1 generation and the other five ones were newly deleted bands.Only 9.8％ of the bands detected in VM1 generation were obtained in VM2 generation.Eventually,nine stable and dear polymorphic bands were recovered and cloned,and DNA sequences of six bands of them were acquired by sequencing.According to the comparative analysis,five fragments sequences were similar to potato chromosome with a similarity rate of 77％-89％,three of them located at the resistance gene cluster; another one fragment had a similarity of 93％ with some regions of the No.5 chromosome in tomato.[Conclusion] 60Co γ-ray irradiation can cause mutation of genomic DNA in potato;there is no significant correlation between the number of polymorphic bands and the irradiation dose; potymorphic bands are characterized by a larger number of deleted bands than that of the added ones.
基金Supported by National Science and Technology Support Project of China (2009BADA7B04, 2011BAD17B01-02)National 973 Project of China (2012CB215300)+1 种基金National 863 Project of China (2012AA101201)National Pasture Modern Industry Technology System of China (CARS-35)~~
文摘[Objective] This study aimed to investigate the mutagenic effect of 60 Co γ-rays irradiation on turf characteristics of Buchloe dactyloides （Nutt.） Engelm. [Method] Buffalo grass were irradiated with 60 Co γ-rays at five different radiation intensities （1 200, 1 400, 1 600, 1 800, 2 000 Gy） to determine the related turf characteristics and analyze the mutagenic effect of 60 Co γ-rays at different radiation intensities on buffalo grass. [Result] Germination rates of buffalo grass irradiated by different radiation intensities of 60 Co γ-rays varied inconsistently, and the root length and bud length were shorter than the control; compared with the control, the height of irradiated seedlings was significantly reduced, and the number of tillers, plant height, leaf length and leaf blade width were smaller than the control; however, the stolon length, stolon diameter and number of stolon nods had no significant difference compared with the control. [Conclusion] This study laid foundation for determining the appropriate radiation intensity of 60 Co γ-rays and selecting useful mutants of buffalo grass.
基金This work was supported by the National Natural Science Foundation of China （No.21373197）, the 100 Talents Program of the Chinese Academy of Sciences, USTC Startup and the Fundamental Research Funds for the Central Universities （WK2060140018）.
文摘We report a γ-ray irradiation reduction method to prepare MnO/reduced graphene oxide （rCO） nanocomposite for the anode of lithium ion batteries. γ-Ray irradiation provides a clean way to generate homogeneously dispersed MnO nanoparticles with finely tuned size on rGO surface without the use of surfactant. The MnO/rGO composite enables a fully charge/discharge in 2 min to gain a reversible specific capacity of 546 （mA-h）/g which is 45 higher than the theoretical value of commercial graphite anode.
基金supported by the National Natural Science Foundation of China(Nos.41874121 and U19A2086)。
文摘Inγ-ray imaging,localization of theγ-ray interaction in the scintillator is critical.Convolutional neural network(CNN)techniques are highly promising for improvingγ-ray localization.Our study evaluated the generalization capabilities of a CNN localization model with respect to theγ-ray energy and thickness of the crystal.The model maintained a high positional linearity(PL)and spatial resolution for ray energies between 59 and 1460 keV.The PL at the incident surface of the detector was 0.99,and the resolution of the central incident point source ranged between 0.52 and 1.19 mm.In modified uniform redundant array(MURA)imaging systems using a thick crystal,the CNNγ-ray localization model significantly improved the useful field-of-view(UFOV)from 60.32 to 93.44%compared to the classical centroid localization methods.Additionally,the signal-to-noise ratio of the reconstructed images increased from 0.95 to 5.63.
文摘Volumetric fraction distribution measurement is a constituent part of process tomography system in oil-water-gas multiphase flow. With the technological development of nuclear radial inspection, dual-energy γ-ray techniques make it possible to investigate the concentration of the different components on the cross-section of oil-water-gas multiphase pipe-flow. The dual-energy gamma-ray technique is based on materials attenuation coefficients measurement comprised of two radioactive isotopes of 241Am and 241Cs which have emission energies at 59.5 keV and 662 keV in this project. Nuclear instruments and data acquisition system were designed to measure the material’s attenuation dose rate and a number of static tests were conducted at the Multiphase Laboratory, Institute of Mechanics, Chinese Academy of Sciences. Three phases of oil-water-gas media were inves- tigated for their possible use to simulate different media volumetric fraction distributions in experimental vessels. Attenuation intensities were measured, and the arithmetic of linear attenuation coefficients and the equations of volumetric fractions were studied. Investigation of an unexpected measurement error from attenuation equations revealed that a modified arithmetic was involved and finally the system achieved acceptable accuracy in experimental research.
基金This work was supported by the National Key Research and Development Project(No.2016YFA0400502)the National Natural Science Foundation of China(No.11775312).
文摘It is of particular interest to investigate nuclear fusion reactions generated by high-intensity lasers in plasma environments that are similar to real astrophysical conditions.We have experimentally investigated2H(d,p)3H,one of the most crucial reactions in big bang nucleosynthesis models,at the Shenguang-Ⅱlaser facility.In this work,we present a new calibration of CR-39 solidstate track detectors,which are widely employed as the main diagnostics in this type of fusion reaction experiment.We measure the dependence of the track diameter on the proton energy.It is found that the track diameters of protons with different energies are likely to be identical.We propose that in this case,the energy of the reaction products can be obtained by considering both the diameters and gray levels of these tracks.The present results would be very helpful for analyzing the2 H(d,p)3H reaction products recorded with the same batch of CR-39 solid-state track detectors.
基金supported by the National Natural Science Foundation of China(Nos.11575090,11605099)the Young Key Teachers Training Program of He’nan Higher Education in China(No.2015GGJS-258)
文摘For a characteristic c-ray with interlaced overlap peak, and the case where its reliable and credible net count cannot be obtained using the current high-purity germanium(HPGe) multichannel γ-ray spectrum software, two new methods are proposed herein to obtain the γ-ray net peak count from the interlaced overlap peak in the HPGe cray spectrometer system, of which one is the symmetric conversion method based on Gaussian distribution and the other is where the energy average value of two close γ-rays is regarded as the γ-ray energy. The experimental results indicate that the two methods mentioned above are reliable and credible. This study is significant for the development of better γ-ray spectrum processing software for measuring complex γ-ray spectra concerning the nuclear reaction cross section, neutron activation analysis, and analysis of transuranium elements, using an HPGe detector.
基金Supported by Beijing Hospitals Authority,Ascent Plan(No.DFL20190201).
文摘AIM:To evaluate the survival outcomes of patients with lacrimal gland adenoid cystic carcinoma who underwent eye-sparing surgery combined with ^(125I)seed implantation radiotherapy or local externalγ-ray radiotherapy.METHODS:In this retrospective comparative case series,the clinical records of 27 primary and 8 recurrent patients were reviewed.Univariate and multivariate analyses were used to identify risk factors associated with distant metastasis(DM),and the overall survival(OS)after the initial surgery was analyzed.RESULTS:The median follow-up after radiotherapy was 36 mo(range 6-120 mo).At the last follow-up after radiotherapy,26(74.3%)patients had no evidence of disease,7(20%)patients had DM,2(5.9%)patients died of DM,and 1 patient with DM was lost to follow-up.Univariate analyses showed that duration of symptoms,bone destruction,T stage classification,and wide excision surgery were risk factors influencing DM(P<0.05).The 5-year and 10-year OS rates after the initial surgery were 95.8%and 79.9%,respectively.The 5-year DM-free survival and disease-free survival rates after radiotherapy were 66.4%and 52.7%,respectively.CONCLUSION:^(125I)seed radiotherapy and local externalγ-ray radiotherapy may have similar therapeutic effects in preventing DM.Patients with T1/T2 stage disease have a better prognosis than those with T3/T4 stage disease.
基金This work was supported by the Natural Science Foundation of Henan Province under grant No. 0611023900.
文摘By using a new method, ^60Co γ-ray irradiation, Fe3O4 magnetic nano-particles were successfully synthesized at room temperature under ambient pressure. The structure, morphology and magnetic properties of these nanoparticles were characterized by X-ray diffraction （XRD）, transmission electron microscope （TEM） and vibrating sample magnetometer （VSM）, respectively. The radiation formation mechanism was also discussed. The results show that the absorbed dose can greatly influence the structure, morphology and magnetic properties of the products. XRD and TEM studies show that the product prepared by γ-ray irradiation （10 kGy） is pure FesO4 phase and the mean diameter of these nano-particles is about 21 nm. The Fe3O4 nano-particles synthesized by γ-ray irradiation （10 kGy） are mainly in small cubic shape and the size uniformity of these particles is good.
