High entropy alloys(HEAs)constituted of single solid solution phase,but remains chemical inhomogeneity in nature due to its multi-principal composition.Currently,existence of nanoscale spinodal decomposition(SD)phase ...High entropy alloys(HEAs)constituted of single solid solution phase,but remains chemical inhomogeneity in nature due to its multi-principal composition.Currently,existence of nanoscale spinodal decomposition(SD)phase in matrix was found to have significant impact on the properties of HEAs.Nevertheless,the morphology evolution and the kinetics of SD is not clear,which hinders in-depth understanding of the structure-property relationship.In this study,we examine the spinodal structures in(FeCoCrNi)85(AlCu)15 HEAs at different states using in-situ small-angle neutron scattering(SANS),in conjunction with transmission electron microscopy technique.The result demonstrates that SD occurred when aging the HEA samples at temperatures ranging from 500 to 800℃,which leads to the phase constitution of NiAlCu-rich and FeCoCr-rich spinodal phases,L1_(2)ordered phases,and FCC matrix.The characteristic wavelength of SD(λ_(SD))grows from 5.31 to 51.26 nm when aging temperature rises from 500 to 800℃,which explains the enhancement of the alloy’s microhardness.The SD kinetics was unraveled by fitting the time-dependentλ_(SD)through in-situ SANS measurement at 700℃.During isothermal treatment at 700℃,theλ_(SD)increases from 10.42 to 17.43 nm with prolonged time,and SD is in the late stage from the exponential trend of theλ_(SD)over time.Moreover,comparing with aging temperature,the aging time has a relatively minor impact on the coarsening of SD.展开更多
Position-sensitive neutron detectors play an important role in neutron scattering studies. Detectors based on ~6LiF/ZnS(Ag) scintillator and wave-shifting fiber have the advantages of high neutron detection efficiency...Position-sensitive neutron detectors play an important role in neutron scattering studies. Detectors based on ~6LiF/ZnS(Ag) scintillator and wave-shifting fiber have the advantages of high neutron detection efficiency, high position resolution,and large-area splicing, and can well meet the requirement of large area neutron detection for neutron diffractometers. An engineering detector prototype based on a ~6LiF/ZnS(Ag) scintillation screen and SiPM array readout was fabricated for the General Purpose Powder Diffractometer of China Spallation Neutron Source(CSNS). The detector has an active area of 196 mm × 444 mm, with a pixel size of 4 mm × 4 mm. The key performances of the detector prototype were tested at the BL20 neutron beam line of CSNS. The test results show that the neutron detection efficiency of the detector was 32% and 42% at wavelengths of 1.4 ? and 2.8 ?, respectively. An interpolated neutron detection efficiency of 40.2% at a wavelength of 2 ? was obtained. The tested neutron efficiency non-uniformity of the detector was 10.2%, which is less than one-half that of the current general purpose powder diffractometer scintillator neutron detectors at CSNS. This work achieves, for the first time, an efficiency uniformity of < 11% in large-area mosaic neutron detectors, alongside significant advancements in electromagnetic interference immunity and cost-effectiveness.展开更多
The single event effects(SEEs)evaluations caused by atmospheric neutrons were conducted on three different convolutional neural network(CNN)models(Yolov3,MNIST,and ResNet50)in the atmospheric neutron irradiation spect...The single event effects(SEEs)evaluations caused by atmospheric neutrons were conducted on three different convolutional neural network(CNN)models(Yolov3,MNIST,and ResNet50)in the atmospheric neutron irradiation spectrometer(ANIS)at the China Spallation Neutron Source(CSNS).The Yolov3 and MNIST models were implemented on the XILINX28-nm system-on-chip(So C).Meanwhile,the Yolov3 and ResNet50 models were deployed on the XILINX 16-nm Fin FET Ultra Scale+MPSoC.The atmospheric neutron SEEs on the tested CNN systems were comprehensively evaluated from six aspects,including chip type,network architecture,deployment methods,inference time,datasets,and the position of the anchor boxes.The various types of SEE soft errors,SEE cross-sections,and their distribution were analyzed to explore the radiation sensitivities and rules of 28-nm and 16-nm SoC.The current research can provide the technology support of radiation-resistant design of CNN system for developing and applying high-reliability,long-lifespan domestic artificial intelligence chips.展开更多
The rapid growth of neutron flux has driven the development of^(3)He-free neutron detectors to satisfy the requirements of the neutron scattering instruments under construction or planned at the China Spallation Neutr...The rapid growth of neutron flux has driven the development of^(3)He-free neutron detectors to satisfy the requirements of the neutron scattering instruments under construction or planned at the China Spallation Neutron Source(CSNS).Position-sensitive neutron detectors with a high counting rate and large area play an important role in the instruments performing neutron measurements in or close to the direct beam.The ceramic gas-electron-multiplier(GEM)detector serves as a promising solution,and considerable work has been done using the small-area GEM neutron detectors.In this article,we designed and constructed a detector prototype utilizing ceramic GEM foils with an effective area of about307 mm×307 mm.To evaluate and investigate their basic characteristics,the Monte Carlo(MC)tool FLUKA was employed and several neutron beam tests were conducted at CSNS.The simulated spatial resolution was basically in agreement with the measured value of 2.50±0.01 mm(FWHM).The wavelength spectra measurement was verified through comparisons with a commercial beam monitor.In addition,a detection efficiency of 4.7±0.1%was achieved for monoenergetic neutrons of 1.59 A wavelength.This is consistent with the simulated result.The results indicate that the large-area ceramic GEM detector is a good candidate to implement neutron beam measurements.Its efficiency can be improved in a cascading manner to approach that reached by traditional^(3)He detectors.展开更多
The neutron capture cross section for^(165)Ho was measured at the backstreaming white neutron beam line(Back-n)of the China Spallation Neutron Source(CSNS)using total energy detection systems,composed of a set of four...The neutron capture cross section for^(165)Ho was measured at the backstreaming white neutron beam line(Back-n)of the China Spallation Neutron Source(CSNS)using total energy detection systems,composed of a set of four C_(6)D_(6)scintillator detectors coupled with pulse height weighting techniques.The resonance parameters were extracted using the multilevel multichannel R-matrix code SAMMY to fit the measured capture yields of the^(165)Ho(n,γ)reaction in the neutron energy range below100 eV.Subsequently,the resonance region’s capture cross sections were reconstructed based on the obtained parameters.Furthermore,the unresolved resonance average cross section of the^(165)Ho(n,γ)reaction was determined relative to that of the standard sample^(197)Au within the neutron energy range of 2 keV to 1 MeV.The experimental data were compared with the recommended nuclear data from the ENDF/B-VIII.0 library,as well as with results of calculations performed using the TALYS-1.9 code.The comparison revealed agreement between the measured^(165)Ho(n,γ)cross sections and these data.The present results are crucial for evaluating the^(165)Ho neutron capture cross section and thus enhance the quality of evaluated nuclear data libraries.They provide valuable guidance for nuclear theoretical models and nuclear astrophysical studies.展开更多
The neutron total cross-section spectrometer(NTOX)applied on the Back-n beamline at the China Spallation Neutron Source(CSNS)is based on a multicell fission chamber and utilizes ^(235,238)U for neutron detection.To re...The neutron total cross-section spectrometer(NTOX)applied on the Back-n beamline at the China Spallation Neutron Source(CSNS)is based on a multicell fission chamber and utilizes ^(235,238)U for neutron detection.To reduce the experimental uncertainty in the resonance energy region of ^(235,238)U and improve the neutron detection efficiency,a fast scintillator-based neutron total cross-section(FAST)spectrometer was designed.A prototype based on a large-area square ^(6)Li-enriched Cs_(2)LiLaBr_(6)(CLLB)scintillator was constructed and beam-tested.The size of the CLLB scintillator was 50.8 mm×50.8 mm×6 mm,and its side was coupled to an array of 1×8 S14160 MPPC to avoid the irradiation from the high-intensity neutrons and rays.The beam test was performed using a broad-energy pulsed neutron and the time-of-flight(TOF)technique on the Back-n beamline.The results demonstrate that the prototype exhibits good neutron/ γ discrimination capability under strong flash irradiation.The prototype was applied to measure the neutron total cross-section of ^(nat)Pb and the result was compared with that obtained using the NTOX.The two results were consistent in the energy region of 0.3 eV to 1 keV,and the prototype showed a higher detection efficiency and did not exhibit fission resonance effect.This type of spectrometer can be used as a complement to the NTOX in the low-energy range and provides a technical reference and framework for developing the FAST spectrometer on the Back-n beamline.展开更多
In-situ exploration of deep-sea seabed resources is a valuable research direction.Neutron activation-based in-situ exploration methods for seabed polymetallic nodules or crust resources are theoretically feasible beca...In-situ exploration of deep-sea seabed resources is a valuable research direction.Neutron activation-based in-situ exploration methods for seabed polymetallic nodules or crust resources are theoretically feasible because of the high content and high neutron capture cross-section of manganese in these nodules or crusts.However,to date,only a few relevant studies have been conducted.In this study,a prototype deep-sea in-situ neutron activation spectrometer(DINAS)was designed for resource exploration.Through an analysis of the principles of the spectrometer combined with Monte Carlo simulations of the physical principles and finite element simulations of deep-sea pressure,the structure and fundamental components of the spectrometer were determined.The inner core of the spectrometer comprised three components:a compact neutron generator for neutron production,gamma-ray detectors,and an electronics system.The gamma-ray detector array of the spectrometer consisted of LaBr_(3)and Bi_(4)Ge_(3)O_(12)scintillation crystals coupled with silicon photomultiplier arrays.The electronics system was divided into two modules to implement the SiPM readout and digital signal analysis along the modular design lines.The experimental activation of neutron beamlines at the China Spallation Neutron Source demonstrated the capability of the spectrometer detectors to detect activated gamma-rays and showed that the spectrometer achieved an energy resolution of 2.8%at 847 keV for the LaBr_(3)detector and 6.7%at 2.113 MeV for the BGO detector.The laboratory model experiment tested the functionality of the spectrometer prototype,whereas the Geant4 simulation verified the reliability of the Monte Carlo method.The method and prototype proposed in this study proved feasible for the in-situ detection of polymetallic nodules or crusts in deep-sea environments.展开更多
This study investigates the performance of a new compact(55 cm×56 cm×48 cm)in situ spin-exchange optical pumping ^(3)He neutron spin filter(NSF)system developed at the China Spallation Neutron Source.The enc...This study investigates the performance of a new compact(55 cm×56 cm×48 cm)in situ spin-exchange optical pumping ^(3)He neutron spin filter(NSF)system developed at the China Spallation Neutron Source.The enclosed NSF cell,filled with3He at 2.53 bar,achieved an initial ^(3)He polarization of approximately 60%.After subsequent improvements in the magnetic field and heating system,this in situ system achieved a ^(3)He polarization of 75.66%±0.09%,resulting in 96.30%neutron polarization at 2A.This highly compact in situ system is equipped with self-supportive features,pre-pumping capabilities,polarization maintenance,and a low-noise nuclear magnetic resonance system.These advantages significantly reduce the preparation time and simplify polarized neutron experiments,making it suitable for various neutron beamlines in China,particularly those with a limited sample space.These characteristics establish it as a quasi-standardized system that plays a vital role in polarized neutron experiments,including those involving polarized neutron imaging,neutron reflection,the performance calibration of polarized neutron instruments,and the neutron optics parity and time reversal experiment.展开更多
Solid-state precipitation is an effective strategy for tuning the mechanical and functional properties of ad-vanced alloys.Structure design and modification necessitate good knowledge of the kinetic evolution of preci...Solid-state precipitation is an effective strategy for tuning the mechanical and functional properties of ad-vanced alloys.Structure design and modification necessitate good knowledge of the kinetic evolution of precipitates during fabrication,which is strongly correlated with defect concentration.For Fe-Ga alloys,giant magnetostriction can be induced by the precipitation of the nanoscale tetragonal L60 phase.By introducing quenched-in vacancies,we significantly enhance the magnetostriction of the aged Fe81Ga19 polycrystalline alloys to~305 ppm,which is close to the level of single crystals.Although vacancies were found to facilitate the generation of the L60 phase,their impact on the precipitation mechanism and kinetics has yet to be revealed.This study combined transmission electron microscopy(TEM)and time-resolved small-angle neutron scattering(SANS)to investigate the precipitation of the L60 phase during the isothermal aging at 350 and 400℃,respectively.The evolution of L60 nanophase in morphology and number density in as-cast(AC)and liquid nitrogen quenched(LN)Fe81Ga19 alloys with aging time were quantitatively compared.Interestingly,the nucleation of the L60 phase proceeds progressively in AC while suddenly in LN specimens,indicating the homogenous to heterogeneous mechanism switching in-duced by concentrated vacancies.Moreover,excess vacancies can change the shape of nanoprecipitates and significantly accelerate the growth and coarsening kinetics.The magnetostrictive coefficient is opti-mized when the size(long-axis)of L60 precipitates lies between 100 and 110Åwith a number density between 3.2-4.3×10-7Å-3.Insight from this study validates the feasibility of achieving high magnetoe-lastic properties through precise manipulation of the nanostructure.展开更多
Boron neutron capture therapy(BNCT)has emerged as a promising treatment for cancers,offering a unique approach to selectively target tumor cells while sparing healthy tissues.Despite its clinical utility,the widesprea...Boron neutron capture therapy(BNCT)has emerged as a promising treatment for cancers,offering a unique approach to selectively target tumor cells while sparing healthy tissues.Despite its clinical utility,the widespread use of fructose-BPA(F-BPA)has been hampered by its limited ability to penetrate the blood-brain barrier(BBB)and potential risks for patients with certain complications such as diabetes,hyperuricemia,and gout,particularly with substantial dosages.Herein,a series of novel BPA derivatives were synthesized.After the primary screening,geniposide-BPA(G-BPA)and salidroside-BPA(S-BPA)exhibited high water solubility,low cytotoxicity and safe profiles for intravenous injection.Furthermore,both G-BPA and S-BPA had demonstrated superior efficacy in vitro against the 4T1 cell line compared with F-BPA.Notably,S-BPA displayed optimal BBB penetration capability,as evidenced by in vitro BBB models and glioblastoma models in vivo,surpassing all other BPA derivative candidates.Meanwhile,GBPA also exhibited enhanced performance relative to the clinical drug F-BPA.In brief,G-BPA and S-BPA,as novel BPA derivatives,demonstrated notable safety profiles and remarkable boron delivery capabilities,thereby offering promising therapeutic options for BNCT in the clinic.展开更多
The neutron-induced total cross sections of natural lead have been measured in a wide energy range(0.3 eV-20 MeV)on the back-streaming white neutron beamline(Back-n)at the China Spallation Neutron Source.Neutron energ...The neutron-induced total cross sections of natural lead have been measured in a wide energy range(0.3 eV-20 MeV)on the back-streaming white neutron beamline(Back-n)at the China Spallation Neutron Source.Neutron energy was determined by the neutron total cross-section spectrometer using the time-of-flight technique.A fast multi-cell fission chamber was used as the neutron detector,and a 10-mm-thick high-purity natural lead sample was employed for the neutron transmission measurements.The on-beam background was determined using Co,In,Ag,and Cd filters.The excitation function of ^(nat)Pb(n,tot)reaction below 20 MeV was calculated using the TALYS-1.96 nuclear-reaction modeling program.The present results were compared with previous results,the evaluated data available in the five major evaluated nuclear data libraries(i.e.,ENDF/B-VIII.0,JEFF-3.3,JENDL-5,CENDL-3.2,and BROND-3.1),and the theoretical calculation curve.Good agreement was found between the new results and those of previous experiments and with the theoretical curves in the corresponding region.This measurement obtained the neutron total cross section of natural lead with good accuracy over a wide energy range and added experimental data in the resonance energy range.This provides more reliable experimental data for nuclear engineering design and nuclear data evaluation of lead.展开更多
High-entropy alloys(HEAs)possess outstanding features such as corrosion resistance,irradiation resistance,and good mechan-ical properties.A few HEAs have found applications in the fields of aerospace and defense.Exten...High-entropy alloys(HEAs)possess outstanding features such as corrosion resistance,irradiation resistance,and good mechan-ical properties.A few HEAs have found applications in the fields of aerospace and defense.Extensive studies on the deformation mech-anisms of HEAs can guide microstructure control and toughness design,which is vital for understanding and studying state-of-the-art structural materials.Synchrotron X-ray and neutron diffraction are necessary techniques for materials science research,especially for in situ coupling of physical/chemical fields and for resolving macro/microcrystallographic information on materials.Recently,several re-searchers have applied synchrotron X-ray and neutron diffraction methods to study the deformation mechanisms,phase transformations,stress behaviors,and in situ processes of HEAs,such as variable-temperature,high-pressure,and hydrogenation processes.In this review,the principles and development of synchrotron X-ray and neutron diffraction are presented,and their applications in the deformation mechanisms of HEAs are discussed.The factors that influence the deformation mechanisms of HEAs are also outlined.This review fo-cuses on the microstructures and micromechanical behaviors during tension/compression or creep/fatigue deformation and the application of synchrotron X-ray and neutron diffraction methods to the characterization of dislocations,stacking faults,twins,phases,and intergrain/interphase stress changes.Perspectives on future developments of synchrotron X-ray and neutron diffraction and on research directions on the deformation mechanisms of novel metals are discussed.展开更多
The utilization of a proton beam from the China Spallation Neutron Source(CSNS)for producing medical radioisotopes is appealing owing to its high current intensity and high energy.The medical isotope production based ...The utilization of a proton beam from the China Spallation Neutron Source(CSNS)for producing medical radioisotopes is appealing owing to its high current intensity and high energy.The medical isotope production based on the proton beam at the CSNS is significant for the development of future radiopharmaceuticals,particularly for theα-emitting radiopharmaceu-ticals.The production yield and activity of typical medical isotopes were estimated using the FLUKA simulation.The results indicate that the 300-MeV proton beam with a power of 100 kW at CSNS-II is highly suitable for proof-of-principle studies of most medical radioisotopes.In particular,this proton beam offers tremendous advantages for the large-scale production of alpha radioisotopes,such as 225Ac,whose theoretical production yield can reach approximately 57 Ci/week.Based on these results,we provide perspectives on the use of CSNS proton beams to produce radioisotopes for medical applications.展开更多
As a non-destructive testing technology,neutron imaging plays an important role in various fields,including material science,nuclear engineering,and fundamental science.An imaging detector with a neutron-sensitive ima...As a non-destructive testing technology,neutron imaging plays an important role in various fields,including material science,nuclear engineering,and fundamental science.An imaging detector with a neutron-sensitive image intensifier has been developed and demonstrated to achieve good spatial resolution and timing resolution.However,the influence of the working voltage on the performance of the neutron-sensitive imaging intensifier has not been studied.To optimize the performance of the neutron-sensitive image intensifier at different voltages,experiments have been performed at the China Spallation Neutron Source(CSNS)neutron beamline.The change in the light yield and imaging quality with different voltages has been acquired.It is shown that the image quality benefits from the high gain of the microchannel plate(MCP)and the high accelerating electric field between the MCP and the screen.Increasing the accelerating electric field is more effective than increasing the gain of MCPs for the improvement of the imaging quality.Increasing the total gain of the MCP stack can be realized more effectively by improving the gain of the standard MCP than that of the n MCP.These results offer a development direction for image intensifiers in the future.展开更多
Nondestructive and noninvasive neutron assays are essential applications of neutron techniques.Neutron resonance transmission analysis(NRTA)is a powerful nondestructive method for investigating the elemental compositi...Nondestructive and noninvasive neutron assays are essential applications of neutron techniques.Neutron resonance transmission analysis(NRTA)is a powerful nondestructive method for investigating the elemental composition of an object.The back-streaming neutron line(Back-n)is a newly built time-of-flight facility at the China Spallation Neutron Source(CSNS)that provides neutrons in the eV to 300 MeV range.A feasibility study of the NRTA method for nuclide identification was conducted at the CSNS Back-n via two test experiments.The results demonstrate that it is feasible to identify different elements and isotopes in samples using the NRTA method at Back-n.This study reveals its potential future applications.展开更多
Neutron resonance imaging(NRI)has recently emerged as an appealing technique for neutron radiography.Its complexity surpasses that of conventional transmission imaging,as it requires a high demand for both a neutron s...Neutron resonance imaging(NRI)has recently emerged as an appealing technique for neutron radiography.Its complexity surpasses that of conventional transmission imaging,as it requires a high demand for both a neutron source and detector.Consequently,the progression of NRI technology has been sluggish since its inception in the 1980s,particularly considering the limited studies analyzing the neutron energy range above keV.The white neutron source(Back-n)at the China Spallation Neutron Source(CSNS)provides favorable beam conditions for the development of the NRI technique over a wide neutron energy range from eV to MeV.Neutron-sensitive microchannel plates(MCP)have emerged as a cutting-edge tool in the field of neutron detection owing to their high temporal and spatial resolutions,high detection efficiency,and low noise.In this study,we report the development of a 10B-doped MCP detector,along with its associated electronics,data processing system,and NRI experiments at the Back-n.Individual heavy elements such as gold,silver,tungsten,and indium can be easily identified in the transmission images by their characteristic resonance peaks in the 1–100 eV energy range;the more difficult medium-weight elements such as iron,copper,and aluminum with resonance peaks in the 1–100 keV energy range can also be identified.In particular,results in the neutron energy range of dozens of keV(Aluminum)are reported here for the first time.展开更多
Neutron-sensitive microchannel plates(nMCPs)have applications in neutron detection,including energy spectrum measurements,neutron-induced cross sections,and neutron imaging.10B-doped MCPs(B-MCPs)have attracted signifi...Neutron-sensitive microchannel plates(nMCPs)have applications in neutron detection,including energy spectrum measurements,neutron-induced cross sections,and neutron imaging.10B-doped MCPs(B-MCPs)have attracted significant attention owing to their potential for exhibiting a high neutron detection efficiency over a large neutron energy range.Good spatial and temporal resolutions are useful for neutron energy-resolved imaging.However,their practical applications still face many technical challenges.In this study,a B-MCP with 10 mol%10B was tested for its response to wide-energy neutrons from eV to MeV at the Back-n white neutron source at the China Spallation Neutron Source.The neutron detection efficiency was calibrated at 1 eV,which is approximately 300 times that of an ordinary MCP and indicates the success of 10 B doping.The factors that caused the reduction in the detection efficiency were simulated and discussed.The neutron energy spectrum obtained using B-MCP was compared with that obtained by other measurement methods,and showed very good consistency for neutron energies below tens of keV.The response is more complicated at higher neutron energy,at which point the elastic and nonelastic reactions of all nuclides of B-MCP gradually become dominant.This is beneficial for the detection of neutrons,as it compensates for the detection efficiency of B-MCP for high-energy neutrons.展开更多
The neutron capture resonance parameters for 159Tb are crucial for validating nuclear models,nucleosynthesis during the neutron capture process,and nuclear technology applications.In this study,resonance analyses were...The neutron capture resonance parameters for 159Tb are crucial for validating nuclear models,nucleosynthesis during the neutron capture process,and nuclear technology applications.In this study,resonance analyses were performed for the neutron capture cross sections of 159Tb measured at the China Spallation Neutron Source(CSNS)backscattering white neutron beamline(Back-n)facility.The resonance parameters were extracted from the R-Matrix code SAMMY and fitted to the experimental capture yield up to the 1.2 keV resolved resonance region(RRR).The average resonance parameters were determined by performing statistical analysis on the set of the resonance parameters in the RRR.These results were used to fit the measured average capture cross sections using the FITACS code in the unresolved resonance region from 2 keV to 1 MeV.The contributions of partial waves l=0,1,2 to the average capture cross sections are reported.展开更多
This paper examines the effect of Fe addition on the microstructure characterized by scanning electron microscopy/electron backscattered diffraction,neutron diffraction,and synchrotron X-ray tomography and the mechani...This paper examines the effect of Fe addition on the microstructure characterized by scanning electron microscopy/electron backscattered diffraction,neutron diffraction,and synchrotron X-ray tomography and the mechanical properties of Al-Mg-Mn-Fe-Cu alloys.The findings reveal that the microstructures of the alloys consisted of an Al matrix,Al_(6)(FeMn),and Al_(2)CuMg phase particles.The addition of Fe significantly increased the yield strength(YS),and ultimate tensile strength(UTS)of the alloys,while reducing elongation.The transformation of the 3D morphology of the Al_(6)(FeMn)phase from separated and fine particles with Chinese-script morphology to interconnected rod-like structure as Fe content increased from 0.1%to 0.8%.This strengthening effect was attributed to the slip lines being blocked at the vicinity of the inter-connected Fe-rich phase,leading to grain rotation and dislocation density increment around the Fe-rich phase,ultimately improving the strength of the alloys.However,the Fe-rich phases and Al_(2)CuMg phases were found to be prone to cracking under tensile stress,resulting in decreased elongation of the alloys.This study provides a potential application in the design and manufacturing of new non-heat-treatable Al alloys for the automotive industry.展开更多
The China Spallation Neutron Source(CSNS)is the fourth pulsed accelerator-driven neutron source in the world,and it achieved its design target of 100 kW in 2020.The planned China Spallation Neutron Source Phase II(CSN...The China Spallation Neutron Source(CSNS)is the fourth pulsed accelerator-driven neutron source in the world,and it achieved its design target of 100 kW in 2020.The planned China Spallation Neutron Source Phase II(CSNS-II)commenced in 2024.The CSNS-II linac design primarily involves the addition of a radio-frequency ion source and a section of a superconducting linear accelerator composed of two types of superconducting cavities,namely double-spoke and six-cell elliptical cavities,after the drift tube linac(DTL).The development of the double-spoke superconducting cavity began in early 2021,and by January 2023,the welding,post-processing,and vertical tests of two 324 MHz double-spoke cavity prototypes were completed,with vertical test gradients of 11.6 and 15 MV/m,and Q_(0)≥3×10^(10)@E_(acc)≤10 MV/m.The R&D of the cryomodule began in January 2022.In October 2023,the clean assembly of the double-spoke cavity string and cold mass installation of the cryomodule commenced,with the installation of the cryomodule and valve box completing in two months.In January 2024,a horizontal test of the cryomodule was completed,making it the first double-spoke cavity cryomodule in China.The test results showed that the maximum gradients of the two superconducting cavities at a pulse width of 4 ms and repetition frequency of 25 Hz were 12.8 and 15.2 MV/m,respectively.This article provides a detailed introduction to the double-spoke superconducting cavity,tuner,coupler,and cryomodule,elaborates on the clean assembly of the cavity string and cold mass installation of the cryomodule,and provides a detailed analysis of the horizontal test results.展开更多
基金financially supported by the National Key Research and Development Program of China(Grant No.2021YFA1600701)the Guangdong Basic and Applied Basic Research Foundation,China(Project No.2021B1515140028)the National Natural Science Foundation of China(Grant No.12275154)。
文摘High entropy alloys(HEAs)constituted of single solid solution phase,but remains chemical inhomogeneity in nature due to its multi-principal composition.Currently,existence of nanoscale spinodal decomposition(SD)phase in matrix was found to have significant impact on the properties of HEAs.Nevertheless,the morphology evolution and the kinetics of SD is not clear,which hinders in-depth understanding of the structure-property relationship.In this study,we examine the spinodal structures in(FeCoCrNi)85(AlCu)15 HEAs at different states using in-situ small-angle neutron scattering(SANS),in conjunction with transmission electron microscopy technique.The result demonstrates that SD occurred when aging the HEA samples at temperatures ranging from 500 to 800℃,which leads to the phase constitution of NiAlCu-rich and FeCoCr-rich spinodal phases,L1_(2)ordered phases,and FCC matrix.The characteristic wavelength of SD(λ_(SD))grows from 5.31 to 51.26 nm when aging temperature rises from 500 to 800℃,which explains the enhancement of the alloy’s microhardness.The SD kinetics was unraveled by fitting the time-dependentλ_(SD)through in-situ SANS measurement at 700℃.During isothermal treatment at 700℃,theλ_(SD)increases from 10.42 to 17.43 nm with prolonged time,and SD is in the late stage from the exponential trend of theλ_(SD)over time.Moreover,comparing with aging temperature,the aging time has a relatively minor impact on the coarsening of SD.
基金Project supported by the National Natural Science Foundation of China (Grant No. 12275181)Guangdong Basic and Applied Basic Research Foundation (Grant No. 2022B1515120071)+1 种基金Promotion Project of Scientific Research Capability of Key Construction Disciplines in Guangdong Province (Grant No. 2022ZDJS118)Natural Science Foundation of Top Talent SZTU (Grant No. GDRC202205)。
文摘Position-sensitive neutron detectors play an important role in neutron scattering studies. Detectors based on ~6LiF/ZnS(Ag) scintillator and wave-shifting fiber have the advantages of high neutron detection efficiency, high position resolution,and large-area splicing, and can well meet the requirement of large area neutron detection for neutron diffractometers. An engineering detector prototype based on a ~6LiF/ZnS(Ag) scintillation screen and SiPM array readout was fabricated for the General Purpose Powder Diffractometer of China Spallation Neutron Source(CSNS). The detector has an active area of 196 mm × 444 mm, with a pixel size of 4 mm × 4 mm. The key performances of the detector prototype were tested at the BL20 neutron beam line of CSNS. The test results show that the neutron detection efficiency of the detector was 32% and 42% at wavelengths of 1.4 ? and 2.8 ?, respectively. An interpolated neutron detection efficiency of 40.2% at a wavelength of 2 ? was obtained. The tested neutron efficiency non-uniformity of the detector was 10.2%, which is less than one-half that of the current general purpose powder diffractometer scintillator neutron detectors at CSNS. This work achieves, for the first time, an efficiency uniformity of < 11% in large-area mosaic neutron detectors, alongside significant advancements in electromagnetic interference immunity and cost-effectiveness.
基金Project supported by the National Natural Science Foundation of China(Grant No.12305303)the Natural Science Foundation of Hunan Province of China(Grant Nos.2023JJ40520,2024JJ2044,and 2021JJ40444)+3 种基金the Science and Technology Innovation Program of Hunan Province,China(Grant No.2020RC3054)the Postgraduate Scientific Research Innovation Project of Hunan Province,China(Grant No.CX20240831)the Natural Science Basic Research Plan in the Shaanxi Province of China(Grant No.2023-JC-QN0015)the Doctoral Research Fund of University of South China(Grant No.200XQD033)。
文摘The single event effects(SEEs)evaluations caused by atmospheric neutrons were conducted on three different convolutional neural network(CNN)models(Yolov3,MNIST,and ResNet50)in the atmospheric neutron irradiation spectrometer(ANIS)at the China Spallation Neutron Source(CSNS).The Yolov3 and MNIST models were implemented on the XILINX28-nm system-on-chip(So C).Meanwhile,the Yolov3 and ResNet50 models were deployed on the XILINX 16-nm Fin FET Ultra Scale+MPSoC.The atmospheric neutron SEEs on the tested CNN systems were comprehensively evaluated from six aspects,including chip type,network architecture,deployment methods,inference time,datasets,and the position of the anchor boxes.The various types of SEE soft errors,SEE cross-sections,and their distribution were analyzed to explore the radiation sensitivities and rules of 28-nm and 16-nm SoC.The current research can provide the technology support of radiation-resistant design of CNN system for developing and applying high-reliability,long-lifespan domestic artificial intelligence chips.
基金Project supported by the National Key R&D Program of China(Grant No.2023YFC2206502)the National Natural Science Foundation of China(Grant Nos.12175254 and 12227810)+1 种基金Guangdong Major Project of Basic and Applied Basic Research(Grant No.2023B0303000003)Guangdong Provincial Key Laboratory of Advanced Particle Detection Technology(Grant No.2024B1212010005)。
文摘The rapid growth of neutron flux has driven the development of^(3)He-free neutron detectors to satisfy the requirements of the neutron scattering instruments under construction or planned at the China Spallation Neutron Source(CSNS).Position-sensitive neutron detectors with a high counting rate and large area play an important role in the instruments performing neutron measurements in or close to the direct beam.The ceramic gas-electron-multiplier(GEM)detector serves as a promising solution,and considerable work has been done using the small-area GEM neutron detectors.In this article,we designed and constructed a detector prototype utilizing ceramic GEM foils with an effective area of about307 mm×307 mm.To evaluate and investigate their basic characteristics,the Monte Carlo(MC)tool FLUKA was employed and several neutron beam tests were conducted at CSNS.The simulated spatial resolution was basically in agreement with the measured value of 2.50±0.01 mm(FWHM).The wavelength spectra measurement was verified through comparisons with a commercial beam monitor.In addition,a detection efficiency of 4.7±0.1%was achieved for monoenergetic neutrons of 1.59 A wavelength.This is consistent with the simulated result.The results indicate that the large-area ceramic GEM detector is a good candidate to implement neutron beam measurements.Its efficiency can be improved in a cascading manner to approach that reached by traditional^(3)He detectors.
基金supported by the National Natural Science Foundation of China(Nos.12465024,12365018,U2032146)Inner Mongolia National Science Foundation(Nos.2024ZD23,2024FX30,2023MS01005)+1 种基金Program for Innovative Research Team in Universities of Inner Mongolia Autonomous Region(NMGIRT2217)Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(NJYT23109)。
文摘The neutron capture cross section for^(165)Ho was measured at the backstreaming white neutron beam line(Back-n)of the China Spallation Neutron Source(CSNS)using total energy detection systems,composed of a set of four C_(6)D_(6)scintillator detectors coupled with pulse height weighting techniques.The resonance parameters were extracted using the multilevel multichannel R-matrix code SAMMY to fit the measured capture yields of the^(165)Ho(n,γ)reaction in the neutron energy range below100 eV.Subsequently,the resonance region’s capture cross sections were reconstructed based on the obtained parameters.Furthermore,the unresolved resonance average cross section of the^(165)Ho(n,γ)reaction was determined relative to that of the standard sample^(197)Au within the neutron energy range of 2 keV to 1 MeV.The experimental data were compared with the recommended nuclear data from the ENDF/B-VIII.0 library,as well as with results of calculations performed using the TALYS-1.9 code.The comparison revealed agreement between the measured^(165)Ho(n,γ)cross sections and these data.The present results are crucial for evaluating the^(165)Ho neutron capture cross section and thus enhance the quality of evaluated nuclear data libraries.They provide valuable guidance for nuclear theoretical models and nuclear astrophysical studies.
基金supported by the National Natural Science Foundation of China(No.12375296)the Key Laboratory of Nuclear Data Foundation(No.JCKY2022201C153)+1 种基金the Science and Technology Innovation Program of Hunan Province(No.2024RC3205)the Natural Science Foundation of Hunan Province,China(No.2024JJ2044).
文摘The neutron total cross-section spectrometer(NTOX)applied on the Back-n beamline at the China Spallation Neutron Source(CSNS)is based on a multicell fission chamber and utilizes ^(235,238)U for neutron detection.To reduce the experimental uncertainty in the resonance energy region of ^(235,238)U and improve the neutron detection efficiency,a fast scintillator-based neutron total cross-section(FAST)spectrometer was designed.A prototype based on a large-area square ^(6)Li-enriched Cs_(2)LiLaBr_(6)(CLLB)scintillator was constructed and beam-tested.The size of the CLLB scintillator was 50.8 mm×50.8 mm×6 mm,and its side was coupled to an array of 1×8 S14160 MPPC to avoid the irradiation from the high-intensity neutrons and rays.The beam test was performed using a broad-energy pulsed neutron and the time-of-flight(TOF)technique on the Back-n beamline.The results demonstrate that the prototype exhibits good neutron/ γ discrimination capability under strong flash irradiation.The prototype was applied to measure the neutron total cross-section of ^(nat)Pb and the result was compared with that obtained using the NTOX.The two results were consistent in the energy region of 0.3 eV to 1 keV,and the prototype showed a higher detection efficiency and did not exhibit fission resonance effect.This type of spectrometer can be used as a complement to the NTOX in the low-energy range and provides a technical reference and framework for developing the FAST spectrometer on the Back-n beamline.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA22020601)the National Natural Science Foundation of China(No.12075237)。
文摘In-situ exploration of deep-sea seabed resources is a valuable research direction.Neutron activation-based in-situ exploration methods for seabed polymetallic nodules or crust resources are theoretically feasible because of the high content and high neutron capture cross-section of manganese in these nodules or crusts.However,to date,only a few relevant studies have been conducted.In this study,a prototype deep-sea in-situ neutron activation spectrometer(DINAS)was designed for resource exploration.Through an analysis of the principles of the spectrometer combined with Monte Carlo simulations of the physical principles and finite element simulations of deep-sea pressure,the structure and fundamental components of the spectrometer were determined.The inner core of the spectrometer comprised three components:a compact neutron generator for neutron production,gamma-ray detectors,and an electronics system.The gamma-ray detector array of the spectrometer consisted of LaBr_(3)and Bi_(4)Ge_(3)O_(12)scintillation crystals coupled with silicon photomultiplier arrays.The electronics system was divided into two modules to implement the SiPM readout and digital signal analysis along the modular design lines.The experimental activation of neutron beamlines at the China Spallation Neutron Source demonstrated the capability of the spectrometer detectors to detect activated gamma-rays and showed that the spectrometer achieved an energy resolution of 2.8%at 847 keV for the LaBr_(3)detector and 6.7%at 2.113 MeV for the BGO detector.The laboratory model experiment tested the functionality of the spectrometer prototype,whereas the Geant4 simulation verified the reliability of the Monte Carlo method.The method and prototype proposed in this study proved feasible for the in-situ detection of polymetallic nodules or crusts in deep-sea environments.
基金supported by the National Science Fund for Distinguished Young Scholars(Grant No.12425512)the National Key Research and Development Program of China(Grant No.2020YFA0406000)+4 种基金the National Natural Science Foundation of China(Grant No.11875265)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(Grant No.ZDKYYQ20190004)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2019B1515120079)Dongguan Introduction Program of Leading Innovative and Entrepreneurial Talents(Grant No.20191122)Guangdong Provincial Key Laboratory of Extreme Conditions,Dongguan Key Laboratory。
文摘This study investigates the performance of a new compact(55 cm×56 cm×48 cm)in situ spin-exchange optical pumping ^(3)He neutron spin filter(NSF)system developed at the China Spallation Neutron Source.The enclosed NSF cell,filled with3He at 2.53 bar,achieved an initial ^(3)He polarization of approximately 60%.After subsequent improvements in the magnetic field and heating system,this in situ system achieved a ^(3)He polarization of 75.66%±0.09%,resulting in 96.30%neutron polarization at 2A.This highly compact in situ system is equipped with self-supportive features,pre-pumping capabilities,polarization maintenance,and a low-noise nuclear magnetic resonance system.These advantages significantly reduce the preparation time and simplify polarized neutron experiments,making it suitable for various neutron beamlines in China,particularly those with a limited sample space.These characteristics establish it as a quasi-standardized system that plays a vital role in polarized neutron experiments,including those involving polarized neutron imaging,neutron reflection,the performance calibration of polarized neutron instruments,and the neutron optics parity and time reversal experiment.
基金supported by the National Natural Science Foundation of China(Grant No.12275154)the Guangdong Basic and Applied Basic Research Foundation,China(Project No.2021B1515140028)+1 种基金the Youth Innovation Promotion Association,CAS(No.2020010)the National Key Research and Development Program of China,grant number(Nos.2021YFA1600701 and 2021YFB3501201).
文摘Solid-state precipitation is an effective strategy for tuning the mechanical and functional properties of ad-vanced alloys.Structure design and modification necessitate good knowledge of the kinetic evolution of precipitates during fabrication,which is strongly correlated with defect concentration.For Fe-Ga alloys,giant magnetostriction can be induced by the precipitation of the nanoscale tetragonal L60 phase.By introducing quenched-in vacancies,we significantly enhance the magnetostriction of the aged Fe81Ga19 polycrystalline alloys to~305 ppm,which is close to the level of single crystals.Although vacancies were found to facilitate the generation of the L60 phase,their impact on the precipitation mechanism and kinetics has yet to be revealed.This study combined transmission electron microscopy(TEM)and time-resolved small-angle neutron scattering(SANS)to investigate the precipitation of the L60 phase during the isothermal aging at 350 and 400℃,respectively.The evolution of L60 nanophase in morphology and number density in as-cast(AC)and liquid nitrogen quenched(LN)Fe81Ga19 alloys with aging time were quantitatively compared.Interestingly,the nucleation of the L60 phase proceeds progressively in AC while suddenly in LN specimens,indicating the homogenous to heterogeneous mechanism switching in-duced by concentrated vacancies.Moreover,excess vacancies can change the shape of nanoprecipitates and significantly accelerate the growth and coarsening kinetics.The magnetostrictive coefficient is opti-mized when the size(long-axis)of L60 precipitates lies between 100 and 110Åwith a number density between 3.2-4.3×10-7Å-3.Insight from this study validates the feasibility of achieving high magnetoe-lastic properties through precise manipulation of the nanostructure.
基金supported by Guangdong Basic and Applied Basic Research Foundation(No.2021B1515120065)National Natural Science Foundation of China(Nos.82202339,32271420,82202307)+3 种基金China Postdoctoral Science Foundation(Nos.2022M711527,2021M701640)Science Fund for Creative Research Groups of Nature Science Foundation of Hebei Province(No.B2021201038)National High-End Foreign Expert Recruitment Plan(No.G2022003007L)Natural Science Foundation of Hebei Province(No.B2023201108).
文摘Boron neutron capture therapy(BNCT)has emerged as a promising treatment for cancers,offering a unique approach to selectively target tumor cells while sparing healthy tissues.Despite its clinical utility,the widespread use of fructose-BPA(F-BPA)has been hampered by its limited ability to penetrate the blood-brain barrier(BBB)and potential risks for patients with certain complications such as diabetes,hyperuricemia,and gout,particularly with substantial dosages.Herein,a series of novel BPA derivatives were synthesized.After the primary screening,geniposide-BPA(G-BPA)and salidroside-BPA(S-BPA)exhibited high water solubility,low cytotoxicity and safe profiles for intravenous injection.Furthermore,both G-BPA and S-BPA had demonstrated superior efficacy in vitro against the 4T1 cell line compared with F-BPA.Notably,S-BPA displayed optimal BBB penetration capability,as evidenced by in vitro BBB models and glioblastoma models in vivo,surpassing all other BPA derivative candidates.Meanwhile,GBPA also exhibited enhanced performance relative to the clinical drug F-BPA.In brief,G-BPA and S-BPA,as novel BPA derivatives,demonstrated notable safety profiles and remarkable boron delivery capabilities,thereby offering promising therapeutic options for BNCT in the clinic.
基金This work is supported by the National Natural Science Foundation of China(No.12375296)the Key Laboratory of Nuclear Data Foundation(No.JCKY2022201C153)+2 种基金the Natural Science Foundation of Hunan Province of China(Nos.2021JJ40444,2020RC3054)the Youth Innovation Promotion Association CAS(No.2023014)the National Key Research and Development Plan(No.2022YFA1603303).
文摘The neutron-induced total cross sections of natural lead have been measured in a wide energy range(0.3 eV-20 MeV)on the back-streaming white neutron beamline(Back-n)at the China Spallation Neutron Source.Neutron energy was determined by the neutron total cross-section spectrometer using the time-of-flight technique.A fast multi-cell fission chamber was used as the neutron detector,and a 10-mm-thick high-purity natural lead sample was employed for the neutron transmission measurements.The on-beam background was determined using Co,In,Ag,and Cd filters.The excitation function of ^(nat)Pb(n,tot)reaction below 20 MeV was calculated using the TALYS-1.96 nuclear-reaction modeling program.The present results were compared with previous results,the evaluated data available in the five major evaluated nuclear data libraries(i.e.,ENDF/B-VIII.0,JEFF-3.3,JENDL-5,CENDL-3.2,and BROND-3.1),and the theoretical calculation curve.Good agreement was found between the new results and those of previous experiments and with the theoretical curves in the corresponding region.This measurement obtained the neutron total cross section of natural lead with good accuracy over a wide energy range and added experimental data in the resonance energy range.This provides more reliable experimental data for nuclear engineering design and nuclear data evaluation of lead.
基金supported by the National Natural Science Foundation of China(Nos.52171098 and 51921001)the State Key Laboratory for Advanced Metals and Materials(No.2022Z-02)+1 种基金the National High-level Personnel of Special Support Program(No.ZYZZ2021001)the Fundamental Research Funds for the Central Universities(Nos.FRF-TP-20-03C2 and FRF-BD-20-02B).
文摘High-entropy alloys(HEAs)possess outstanding features such as corrosion resistance,irradiation resistance,and good mechan-ical properties.A few HEAs have found applications in the fields of aerospace and defense.Extensive studies on the deformation mech-anisms of HEAs can guide microstructure control and toughness design,which is vital for understanding and studying state-of-the-art structural materials.Synchrotron X-ray and neutron diffraction are necessary techniques for materials science research,especially for in situ coupling of physical/chemical fields and for resolving macro/microcrystallographic information on materials.Recently,several re-searchers have applied synchrotron X-ray and neutron diffraction methods to study the deformation mechanisms,phase transformations,stress behaviors,and in situ processes of HEAs,such as variable-temperature,high-pressure,and hydrogenation processes.In this review,the principles and development of synchrotron X-ray and neutron diffraction are presented,and their applications in the deformation mechanisms of HEAs are discussed.The factors that influence the deformation mechanisms of HEAs are also outlined.This review fo-cuses on the microstructures and micromechanical behaviors during tension/compression or creep/fatigue deformation and the application of synchrotron X-ray and neutron diffraction methods to the characterization of dislocations,stacking faults,twins,phases,and intergrain/interphase stress changes.Perspectives on future developments of synchrotron X-ray and neutron diffraction and on research directions on the deformation mechanisms of novel metals are discussed.
基金the National Natural Science Foundation of China(No.12075135)the China Postdoctoral Science Foundation(No.2022M721908).
文摘The utilization of a proton beam from the China Spallation Neutron Source(CSNS)for producing medical radioisotopes is appealing owing to its high current intensity and high energy.The medical isotope production based on the proton beam at the CSNS is significant for the development of future radiopharmaceuticals,particularly for theα-emitting radiopharmaceu-ticals.The production yield and activity of typical medical isotopes were estimated using the FLUKA simulation.The results indicate that the 300-MeV proton beam with a power of 100 kW at CSNS-II is highly suitable for proof-of-principle studies of most medical radioisotopes.In particular,this proton beam offers tremendous advantages for the large-scale production of alpha radioisotopes,such as 225Ac,whose theoretical production yield can reach approximately 57 Ci/week.Based on these results,we provide perspectives on the use of CSNS proton beams to produce radioisotopes for medical applications.
基金Project supported by the National Key R&D Program of China (Grant Nos.2023YFC2206502 and 2021YFA1600703)the National Natural Science Foundation of China (Grant Nos.12175254 and 12227810)the Guangdong–Hong Kong–Macao Joint Laboratory for Neutron Scattering Science and Technology。
文摘As a non-destructive testing technology,neutron imaging plays an important role in various fields,including material science,nuclear engineering,and fundamental science.An imaging detector with a neutron-sensitive image intensifier has been developed and demonstrated to achieve good spatial resolution and timing resolution.However,the influence of the working voltage on the performance of the neutron-sensitive imaging intensifier has not been studied.To optimize the performance of the neutron-sensitive image intensifier at different voltages,experiments have been performed at the China Spallation Neutron Source(CSNS)neutron beamline.The change in the light yield and imaging quality with different voltages has been acquired.It is shown that the image quality benefits from the high gain of the microchannel plate(MCP)and the high accelerating electric field between the MCP and the screen.Increasing the accelerating electric field is more effective than increasing the gain of MCPs for the improvement of the imaging quality.Increasing the total gain of the MCP stack can be realized more effectively by improving the gain of the standard MCP than that of the n MCP.These results offer a development direction for image intensifiers in the future.
基金This work was supported by the National Natural Science Foundation of China(No.12035017)Youth Innovation Promotion Association CAS(No.2023014)Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515010360 and 2022B1515120032).
文摘Nondestructive and noninvasive neutron assays are essential applications of neutron techniques.Neutron resonance transmission analysis(NRTA)is a powerful nondestructive method for investigating the elemental composition of an object.The back-streaming neutron line(Back-n)is a newly built time-of-flight facility at the China Spallation Neutron Source(CSNS)that provides neutrons in the eV to 300 MeV range.A feasibility study of the NRTA method for nuclide identification was conducted at the CSNS Back-n via two test experiments.The results demonstrate that it is feasible to identify different elements and isotopes in samples using the NRTA method at Back-n.This study reveals its potential future applications.
基金supported by the National Natural Science Foundation of China(No.12035017)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515030074)。
文摘Neutron resonance imaging(NRI)has recently emerged as an appealing technique for neutron radiography.Its complexity surpasses that of conventional transmission imaging,as it requires a high demand for both a neutron source and detector.Consequently,the progression of NRI technology has been sluggish since its inception in the 1980s,particularly considering the limited studies analyzing the neutron energy range above keV.The white neutron source(Back-n)at the China Spallation Neutron Source(CSNS)provides favorable beam conditions for the development of the NRI technique over a wide neutron energy range from eV to MeV.Neutron-sensitive microchannel plates(MCP)have emerged as a cutting-edge tool in the field of neutron detection owing to their high temporal and spatial resolutions,high detection efficiency,and low noise.In this study,we report the development of a 10B-doped MCP detector,along with its associated electronics,data processing system,and NRI experiments at the Back-n.Individual heavy elements such as gold,silver,tungsten,and indium can be easily identified in the transmission images by their characteristic resonance peaks in the 1–100 eV energy range;the more difficult medium-weight elements such as iron,copper,and aluminum with resonance peaks in the 1–100 keV energy range can also be identified.In particular,results in the neutron energy range of dozens of keV(Aluminum)are reported here for the first time.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515030074)the National Natural Science Foundation of China(No.12035017)。
文摘Neutron-sensitive microchannel plates(nMCPs)have applications in neutron detection,including energy spectrum measurements,neutron-induced cross sections,and neutron imaging.10B-doped MCPs(B-MCPs)have attracted significant attention owing to their potential for exhibiting a high neutron detection efficiency over a large neutron energy range.Good spatial and temporal resolutions are useful for neutron energy-resolved imaging.However,their practical applications still face many technical challenges.In this study,a B-MCP with 10 mol%10B was tested for its response to wide-energy neutrons from eV to MeV at the Back-n white neutron source at the China Spallation Neutron Source.The neutron detection efficiency was calibrated at 1 eV,which is approximately 300 times that of an ordinary MCP and indicates the success of 10 B doping.The factors that caused the reduction in the detection efficiency were simulated and discussed.The neutron energy spectrum obtained using B-MCP was compared with that obtained by other measurement methods,and showed very good consistency for neutron energies below tens of keV.The response is more complicated at higher neutron energy,at which point the elastic and nonelastic reactions of all nuclides of B-MCP gradually become dominant.This is beneficial for the detection of neutrons,as it compensates for the detection efficiency of B-MCP for high-energy neutrons.
基金supported by the National Natural Science Foundation of China(Nos.12365018,U2032146,12465024)Natural Science Foundation of Inner Mongolia(Nos.2023MS01005,2024ZD23,2024FX30)the program of Innovative Research Team and Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(Nos.NMGIRT2217,NJYT23109)。
文摘The neutron capture resonance parameters for 159Tb are crucial for validating nuclear models,nucleosynthesis during the neutron capture process,and nuclear technology applications.In this study,resonance analyses were performed for the neutron capture cross sections of 159Tb measured at the China Spallation Neutron Source(CSNS)backscattering white neutron beamline(Back-n)facility.The resonance parameters were extracted from the R-Matrix code SAMMY and fitted to the experimental capture yield up to the 1.2 keV resolved resonance region(RRR).The average resonance parameters were determined by performing statistical analysis on the set of the resonance parameters in the RRR.These results were used to fit the measured average capture cross sections using the FITACS code in the unresolved resonance region from 2 keV to 1 MeV.The contributions of partial waves l=0,1,2 to the average capture cross sections are reported.
基金support from the Natural Science Foundation of China(Nos.52104373,52074131,and 51974092)the Basic and Applied Basic Foundation of Guangdong Province(No.2020B1515120065)。
文摘This paper examines the effect of Fe addition on the microstructure characterized by scanning electron microscopy/electron backscattered diffraction,neutron diffraction,and synchrotron X-ray tomography and the mechanical properties of Al-Mg-Mn-Fe-Cu alloys.The findings reveal that the microstructures of the alloys consisted of an Al matrix,Al_(6)(FeMn),and Al_(2)CuMg phase particles.The addition of Fe significantly increased the yield strength(YS),and ultimate tensile strength(UTS)of the alloys,while reducing elongation.The transformation of the 3D morphology of the Al_(6)(FeMn)phase from separated and fine particles with Chinese-script morphology to interconnected rod-like structure as Fe content increased from 0.1%to 0.8%.This strengthening effect was attributed to the slip lines being blocked at the vicinity of the inter-connected Fe-rich phase,leading to grain rotation and dislocation density increment around the Fe-rich phase,ultimately improving the strength of the alloys.However,the Fe-rich phases and Al_(2)CuMg phases were found to be prone to cracking under tensile stress,resulting in decreased elongation of the alloys.This study provides a potential application in the design and manufacturing of new non-heat-treatable Al alloys for the automotive industry.
文摘The China Spallation Neutron Source(CSNS)is the fourth pulsed accelerator-driven neutron source in the world,and it achieved its design target of 100 kW in 2020.The planned China Spallation Neutron Source Phase II(CSNS-II)commenced in 2024.The CSNS-II linac design primarily involves the addition of a radio-frequency ion source and a section of a superconducting linear accelerator composed of two types of superconducting cavities,namely double-spoke and six-cell elliptical cavities,after the drift tube linac(DTL).The development of the double-spoke superconducting cavity began in early 2021,and by January 2023,the welding,post-processing,and vertical tests of two 324 MHz double-spoke cavity prototypes were completed,with vertical test gradients of 11.6 and 15 MV/m,and Q_(0)≥3×10^(10)@E_(acc)≤10 MV/m.The R&D of the cryomodule began in January 2022.In October 2023,the clean assembly of the double-spoke cavity string and cold mass installation of the cryomodule commenced,with the installation of the cryomodule and valve box completing in two months.In January 2024,a horizontal test of the cryomodule was completed,making it the first double-spoke cavity cryomodule in China.The test results showed that the maximum gradients of the two superconducting cavities at a pulse width of 4 ms and repetition frequency of 25 Hz were 12.8 and 15.2 MV/m,respectively.This article provides a detailed introduction to the double-spoke superconducting cavity,tuner,coupler,and cryomodule,elaborates on the clean assembly of the cavity string and cold mass installation of the cryomodule,and provides a detailed analysis of the horizontal test results.
