This study explores the impact of bismuth oxide(Bi_(2)O_(3))on the optical and radiation shielding properties of transparent,lead-free thulium-doped bismuth borotellurite radiation shielding glass.The investigated gla...This study explores the impact of bismuth oxide(Bi_(2)O_(3))on the optical and radiation shielding properties of transparent,lead-free thulium-doped bismuth borotellurite radiation shielding glass.The investigated glass composition follows the formula[(TeO_(2))_(75)(B_(2)O_(3))_(25)]_(98-x)(Bi_(2)O_(3))_x[Tm_(2)O_(3)]_(2),where x=0 mol%,5 mol%,10 mol%,15 mol%,20 mol%,25 mol%,and 30 mol%.All glass samples remain transparent,with an optical bandgap(E_(opt))exceeding 3.1 e V,ensuring visible light transmission.Radiation shielding data from Phy-X and XCom reveal interactions of the photoelectric effect,Compton scattering,and pair production,with minimal relative difference in mass attenuation coefficient(MAC)which is between0.05 and 0.56.At 0.662 Me V photon energy,the 20 mol%and 25 mol%Bi_(2)O_(3)glasses exhibit significantly higher Phy-X MAC values than other samples,except RS 520 glass,which contains 71%Pb O.Despite incorporating only up to 25 mol%Bi_(2)O_(3),these glasses outperform others in density,half-value layer(HVL),and mean free path(MFP).Correlating E_(opt)and MAC,the 20 mol%Bi_(2)O_(3)glass is the best candidate for transparent radiation shielding glass due to its wide optical bandgap which prevents ionization of trapped holes.Significantly,the linkage between MFP and molar refraction was also discovered based on the particle size influence on both parameters.展开更多
The recycled cathode ray tube(CRT)funnel glass was used as replacement of magnetite sand in the concrete,and its mass replacement rates were 0,20%,40%and 60%,respectively.The flowability,apparent density and mechanica...The recycled cathode ray tube(CRT)funnel glass was used as replacement of magnetite sand in the concrete,and its mass replacement rates were 0,20%,40%and 60%,respectively.The flowability,apparent density and mechanical properties of the radiation shielding concrete were investigated,while itsγ-ray radiation shielding parameters such as linear and mass attenuation coefficients(μandμm,respectively),thickness values of half-value layer(hHVL)and tenth-value layer(hTVL)were obtained by theoretical calculation,experiment and Monte.Carlo N-Particle(MCNP)simulation code.The experimental results show that the flowability of the concrete increases significantly,whilst its apparent density,compressive strength and static elastic modulus decrease slightly.The calculated,simulated and experimentalμm,μ,hHVL and hTVL values of all concrete samples are very consistent at the sameγ-ray photon energy,and it is feasible to use MCNP code to simulateγ-ray radiation shielding parameters of materials.The calculated results show that in a wide range ofγ-ray photon energy,theμm value of the concrete with CRT funnel glass replacing magnetite sand is improved effectively,and its radiation shielding performances are the same as those of the control concrete(M.1).By comprehensively comparing the flowability,mechanical properties andγ-ray radiation shielding properties,the concrete samples with 20%.40%funnel glass as fine aggregate have good performances.展开更多
A synchrotron-based proton therapy(PT)facility that conforms with the requirement of future development trend in compact PT can be operated without an energy selection system.This article demonstrates a novel radiatio...A synchrotron-based proton therapy(PT)facility that conforms with the requirement of future development trend in compact PT can be operated without an energy selection system.This article demonstrates a novel radiation shielding design for this purpose.Various FLUKAbased Monte Carlo simulations have been performed to validate its feasibility.In this design,two different shielding scenarios(3-m-thick concrete and 2-m-thick iron–concrete)are proved able to reduce the public annual dose to the limit of 0.1 mSv/year.The calculation result shows that the non-primary radiation from a PT system without an inner shielding wall complies with the IEC 60601-2-64 international standard,making a single room a reality.Moreover,the H/D value of this design decreases from 2.14 to 0.32 mSv/Gy when the distance ranges from 50 to 150 cm from the isocenter,which is consistent with the previous result from another study.By establishing a typical time schedule and procedures in a treatment day for a single room in the simulation,a non-urgent machine maintenance time of 10 min after treatment is recommended,and the residual radiation level in most areas can be reduced to 2.5 lSv/h.The annual dose for radiation therapists coming from the residual radiation is 1 mSv,which is 20%of the target design.In general,this shielding design ensures a low cost and compact facility compared with the cyclotron-based PT system.展开更多
With continuous enhancement of gas-turbine inlet temperature and rapid increase of radiant heat transfer,thermal barrier coating(TBC)materials with a combination of low thermal conductivity and good high-temperature t...With continuous enhancement of gas-turbine inlet temperature and rapid increase of radiant heat transfer,thermal barrier coating(TBC)materials with a combination of low thermal conductivity and good high-temperature thermal radiation shielding performance play vital roles in ensuring the durability of metallic blades.However,yttria-stabilized zirconia(YSZ),as the state-of-the-art TBC and current industry standard,is unable to meet such demands since it is almost translucent to high-temperature thermal radiation.Besides,poor corrosion resistance of YSZ to molten calcia-magnesia-alumina-silicates(CMAS)also impedes its application in sand,dust,or volcanic ash laden environments.In order to improve the hightemperature thermal radiation shielding performance and CMAS resistance of YSZ and further reduce its thermal conductivity,two medium-entropy(ME)oxide ceramics,ME(Y,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)and ME(Ta,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2),were designed and prepared by pressureless sintering of binary powder compacts in this work.ME(Y,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)presents cubic structure but a trace amount of secondary phase,while ME(Ta,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)displays a combination of tetragonal phase(81.6 wt.%)and cubic phase(18.4 wt.%).Both ME(Y,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)and ME(Ta,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)possess better high-temperature thermal radiation shielding performance than YSZ.Especially,the high-temperature thermal radiation shielding performance of ME(Ta,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)is superior to that of ME(Y,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)due to its narrower band gap and correspondingly higher infrared absorbance(above 0.7)at the waveband of 1 to 5μm.The two ME oxides also display significantly lower thermal conductivity than YSZ and close thermal expansion coefficients(TECs)to YSZ and Ni-based superalloys.In addition,the two ME oxides possess excellent CMAS resistance.After attack by molten CMAS at 1250℃for 4 h,merely~2μm thick penetration layer has been formed and the structure below the penetration layer is still intact.These results demonstrate that ME(Me,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)(Me=Y and Ta),especially ME(Ta,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2),are promising thermal barrier materials for high-temperature thermal radiation shielding and CMAS blocking.展开更多
A new method to prepare radiation shielding functional aggregate is described, and an appropriate mix ratio and a reasonable calcinated condition was engaged. The y-ray shielding capability of both the new functional ...A new method to prepare radiation shielding functional aggregate is described, and an appropriate mix ratio and a reasonable calcinated condition was engaged. The y-ray shielding capability of both the new functional aggregates and some other nature aggregates had been measured. The linear attenuation coefficients （μ, cm-1） of these aggregates had been calculated at photon energies from 1 keV to 10GeV using XCOM program, and measured at the photon energies of 662 keV, showing good agreement between experimental and calculated results. The results show that the y-ray shielding capacity of the new functional aggregates has been improved substantially compared with basalt, almost equal to serpentine and high-titanium slag, and up to 80% to barite.展开更多
The radiation shielding characteristics of 50wt% WO3/E44 epoxy composite in various gamma energies from 80 keV to 1.33 MeV are investigated via the MCNP code. Thus two scales are considered for WOa filler particles： ...The radiation shielding characteristics of 50wt% WO3/E44 epoxy composite in various gamma energies from 80 keV to 1.33 MeV are investigated via the MCNP code. Thus two scales are considered for WOa filler particles： micro and nano with sizes of i #m and 5Onto, respectively. The simulation results show that W03 nano particles exhibit a larger increase in linear attenuation coefficient in comparison with micro size particles. Finally, validation of simulation results with the published experimental data shows a good agreement.展开更多
Heavy concrete currently used for construction contains special materials that are expensive and difficult to work with.This study replaced natural aggregate（stones） in concrete with round steel balls,which are inex...Heavy concrete currently used for construction contains special materials that are expensive and difficult to work with.This study replaced natural aggregate（stones） in concrete with round steel balls,which are inexpensive and easily obtainable.The diameters of the steel balls were 0.5 and 1 cm,and their density was 7.8 kg/m3.Dense packing mixture methods were used to produce heavy concrete with densities of 3500 and 5000 kg/m3.The various properties of this concrete were tested according to the standards of the American Society for Testing and Materials（ASTM）.The results indicated that the construction slump of the concrete could reach 260-280 mm and its slump flow could reach 610-710 mm.More important,its compressive strength could reach 8848 MPa.These results will significantly alter traditional construction methods that use heavy concrete and enhance innovative ideas for structural design.展开更多
The variation of air temperature measurement errors using two different radiation shields （DTR502B Vaisala,Finland,and HYTFZ01,Huayun Tongda Satcom,China） was studied.Datasets were collected in the field at the Daxi...The variation of air temperature measurement errors using two different radiation shields （DTR502B Vaisala,Finland,and HYTFZ01,Huayun Tongda Satcom,China） was studied.Datasets were collected in the field at the Daxing weather station in Beijing from June 2011 to May 2012.Most air temperature values obtained with these two commonly used radiation shields were lower than the reference records obtained with the new Fiber Reinforced Polymers （FRP） Stevenson screen.In most cases,the air temperature errors when using the two devices were smaller on overcast and rainy days than on sunny days; and smaller when using the imported rather than the Chinese shield.The measured errors changed sharply at sunrise and sunset,and reached maxima at noon.Their diurnal variation characteristics were,naturally,related to changes in solar radiation.The relationships between the record errors,global radiation,and wind speed were nonlinear.An improved correction method was proposed based on the approach described by Nakamura and Mahrt （2005） （NM05）,in which the impact of the solar zenith angle （SZA） on the temperature error is considered and extreme errors due to changes in SZA can be corrected effectively.Measurement errors were reduced significantly after correction by either method for both shields.The error reduction rate using the improved correction method for the Chinese and imported shields were 3.3％ and 40.4％ higher than those using the NM05 method,respectively.展开更多
Purpose The High Energy Photon Source(HEPS)is currently under construction in China and will be the brightest synchrotron radiation facility in the world.To solve the gas bremsstrahlung and synchrotron radiation hazar...Purpose The High Energy Photon Source(HEPS)is currently under construction in China and will be the brightest synchrotron radiation facility in the world.To solve the gas bremsstrahlung and synchrotron radiation hazard at HEPS beamlines,a comprehensive radiation study is performed.Method The Monte Carlo method is used to analyze the radiation field in the first optics enclosure at HEPS beamlines.First,the radiation sources including gas bremsstrahlung and synchrotron radiation are estimated.Then,the distribution of the radiation field in the hutch is calculated.Conservative parameters and a typical beamline geometry are used in the calculations.Finally,the shielding recommendations are summarized.Results and Conclusion In this paper,the considerations and bulk shielding design of the first optics enclosure at HEPS beamlines are described.The design satisfies the requirements of the radiation safety principles.展开更多
A novel lightweight,radiation-shielding Mg-Ta-Al layered metal-matrix composite(LMC)was successful designed by doping the extremely refractory metal(Ta)into Mg sheets.These Mg-based LMCs sheets shows excellent radiati...A novel lightweight,radiation-shielding Mg-Ta-Al layered metal-matrix composite(LMC)was successful designed by doping the extremely refractory metal(Ta)into Mg sheets.These Mg-based LMCs sheets shows excellent radiation-dose shield effect,about 145 krad·a^(−1),which is about 17 times of traditional Mg alloy,while its surface density is only about 0.9 g·cm^(−2),reducing by 60%than that of pure Ta.The quantitate relationship between radiation-dose and the materials’thickness was also confirmed to the logistic function when the surface density is in the range of 0.6-1.5 g·cm^(−2).Meantime,the rolling parameters,interface microstructure and mechanical properties in both as-rolled and annealing treated samples were evaluated.The sheets possess a special dissimilar atoms diffusion transitional zone containing an obvious inter-diffusion Mg-Al interface and the unique micro-corrugated Ta-Al interface,as well as a thin Al film with a thickness of about 10μm.The special zone could reduce the stress concentration and enhance the strength of Mg-Ta-Al LMCs.The interface bonding strength reaches up to 54-76 MPa.The ultimate tensile strength(UTS)and yield strength(TYS)of the Mg-Ta-Al sheet were high to 413 MPa and 263 MPa,respectively,along with an elongation of 5.8%.The molecular dynamics(MD)analysis results show that the two interfaces exhibit different formation mechanism,the Mg-Al interface primarily depended on Mg/Al atoms diffusion basing point defects movement,while the Ta-Al interface with a micro-interlock pining shape formed by close-packed planes slipping during high temperature strain-induced deformation process.展开更多
Solar radiation is often shielded by terrain relief,especially in mountainous areas,before reaching the surface of the Earth.The objective of this paper is to study the spatial structures of the shielded astronomical ...Solar radiation is often shielded by terrain relief,especially in mountainous areas,before reaching the surface of the Earth.The objective of this paper is to study the spatial structures of the shielded astronomical solar radiation(SASR)and the possible sunshine duration(PSD)over the Loess Plateau.To this end,we chose six test areas representing different landforms over the Loess Plateau and the software package of Matlab was used as the main computing platform.In each test area,5-m-resolution digital elevation model established from 1:10,000 scale topographic maps was used to compute the corresponding slope,SASR and PSD.Then,we defined the concepts of the slope-mean SASR spectrum and the slope-mean PSD spectrum,and proposed a method to extract them from the computed slope,SASR and PSD over rectangular analysis windows.Using this method,we found both spectrums in a year or in a season for each of the four seasons in the six test areas.Each spectrum was found only when the area of the corresponding rectangular analysis window was greater than the corresponding stable area of the spectrum.The values of the two spectrums decreased when the slope increased.Furthermore,the values of the stable areas of the spectrums in a year or in a season were positively correlated with the variable coefficients of the slope or the profile curvature.The values of the stable areas of the two spectrums in a year or in a season may represent the minimum value of test areas for corresponding future research on the spatial structures of the SASR or PSD.All the findings herein suggest that the spatial structures of the PSD and the SASR are caused by the interactions between solar radiation and terrain relief and that the method for extracting either spectrum is effective for detecting their spatial structures.This study may deepen our understanding of the spatial structure of solar radiation and help us further explore the distribution of solar energy in mountainous regions.展开更多
The radiation generated by nuclear reaction is harmful to human body and equipment,thus the radiation shielding materials that employ the shielding ability from neutron and gamma rays are the best candidates according...The radiation generated by nuclear reaction is harmful to human body and equipment,thus the radiation shielding materials that employ the shielding ability from neutron and gamma rays are the best candidates according to application situations and radiation sources.In this paper,the researches of metal-based neutron and gamma rays or multiple purpose shielding materials are systematically summarized,and the respective and principal problems of these materials with respect to shielding effectiveness and other performances,such as corrosion,mechanical properties,manufacture,etc.,are discussed.Finally,the prospect of shielding materials is outlined,which suggests that the development of highly efficient and multiply functional radiation shielding materials with good environmental compatibility is one of the future development trends.展开更多
The 52%energy of the solar radiation is contributed by near-infrared radiation(NIR,780-2500 nm).Therefore,the material design for the energy-saving smart window,which can effectively shield NIR and has acceptable visi...The 52%energy of the solar radiation is contributed by near-infrared radiation(NIR,780-2500 nm).Therefore,the material design for the energy-saving smart window,which can effectively shield NIR and has acceptable visible transmittance,is vital to save the energy consumed on the temperature control system.It is important to find a non-toxic stable material with excellent NIR-shielding ability and acceptable visible transmittance.The systematic first-principles study on Li_(x)Sn_(y)WO_(3)(x=0,0.33,0.66,and y=0,0.33)exhibits that the chemical stability is a positive correlation with the doping concentration.After doping,the Fermi-energy upshifts into the conduction band,and the material shows metal-like characteristics.Therefore,these structures Li_(x)Sn_(y)WO_(3)(except the structure with x=0.33 and y=0)show pronounced improvement of NIR shielding ability.Our results indicate that when x=0 and y=0.33,the material exhibits the strongest NIR-shielding ability,satisfying chemical stability,wide NIR-shielding range(780-2500 nm),and acceptable visible transmittance.This work provides a good choice for experimental study on NIR shielding material for the energy-saving window.展开更多
Purpose The research focuses on the related measurement and shielding works for solving the spatial electromagnetic radiation and interference problems of the BEPCⅡLinac.Methods The radiation frequency and intensity ...Purpose The research focuses on the related measurement and shielding works for solving the spatial electromagnetic radiation and interference problems of the BEPCⅡLinac.Methods The radiation frequency and intensity can be determined by using a set of antennas connected with a spectrum analyser.Results The source of the radiation is located on the cable connectors of some device panels.The radiation intensity is significantly reduced after wrapping the connectors with the radiation shielding tape.Conclusions The entire research process includes the selection of a domestically made ultra-wideband antenna,the proposal of the measurement methods,the locating of the radiation source,the performance measurement of the radiation shielding tape and the shielding of the radiation.It provides a whole set of feasible solutions for similar problems in accelerators.展开更多
Nuclear power is essential for sustainable energy infrastructure and economic development,necessitating materials for high-radiation environments that can facilitate visualization and observation.Conventional lead gla...Nuclear power is essential for sustainable energy infrastructure and economic development,necessitating materials for high-radiation environments that can facilitate visualization and observation.Conventional lead glass is inadequate for future requirements due to radiation-induced darkening,poor mechanical properties,and toxicity.Therefore,there is urgent to find new window materials that offer multi-ionization shielding(particularly against deep-penetrating gamma ray,γ,and neutron,n,radiations),desirable opto-mechanical properties,service stability against darkening,and non-toxicity.In this study,we report a family of transparent rare-earth pyrochlore ceramics La_(x)Gd_(2-x)Zr_(2)O_(7),offering unique chemo-physical properties that are ideal for robust radiation shielding windows.Remarkably,we demonstrated the capability of maintaining high transparency under heavy-dose exposure to 1000 kGy ^(60)Coγradiation.We observed the service stability against radiation darkening can be greatly enhanced with La-rich compositions,while Gd-rich compositions undergo shallow darkening that can be reversibly recovered under visible light.This behavior is attributed to mitigated oxygen migration from 48f to 8a in La-rich compositions,which have high pyrochlore phase stability and well-ordered atomic structures,and reversible oxygen migration between 48f and 8a in Gd-rich compositions,which remain active at room temperature.Our proposal and demonstration unlock ample opportunities in designing functional transparent ceramics as window materials for demanding applications in high-radiation environments.展开更多
This study investigated the characteristics of bremsstrahlung and induced neutrons from the elec- tron storage ring in the Shanghai Synchrotron Radiation Facility (SSRF).The EGSnrc and MCNP Monte Carlo code has been u...This study investigated the characteristics of bremsstrahlung and induced neutrons from the elec- tron storage ring in the Shanghai Synchrotron Radiation Facility (SSRF).The EGSnrc and MCNP Monte Carlo code has been used to perform the assess neutron and photon dose profiles for a variety of shield ma- terials ranging from 5 to 115cm thick.The Monte Carlo simulations show that single material such as lead, iron and polyethylene have been found to be ineffective biological shield materials,while the mixed materials serve as effective shields for shielding high energy neutron.Mixed materials such as lead or iron combined with polyethylene or with concrete are good materials combination for high energy neutron radiation shield.And high-Z materials such as lead or iron combine with low-Z material containing some hydrogen such polyethylene are effective for shielding high energy neutrons as well as bremsstrahlung.展开更多
Purpose The high-energy photon source(HEPS)is the first fourth-generation light source under construction in China.It is designed to operate at an average current of 200 mA stored beam current with a top-up model at 6...Purpose The high-energy photon source(HEPS)is the first fourth-generation light source under construction in China.It is designed to operate at an average current of 200 mA stored beam current with a top-up model at 6 GeV energy.Considering the linac radiation shielding design,a suitable beam loss scenario,optimized thickness for the bulk shielding and detailed structure design for dumps should be proposed.In this paper,the beam loss scenarios were determined and categorized as normal;the dose limits were presented;using these scenarios and the dose limits,the thickness of the linac tunnel was calculated and detailed designs of the main beam dumps were established.The material selection and size setting of the low-power electron beam dump were discussed.Method The Monte Carlo code is a good choice to simulate the radiation analysis.And the iSHIELD11 was used to verify the simulation calculations.Result and conclusion The designs of the linac bulk shield and dumps satisfied the requirements of radiation protection.展开更多
We present the main features of the ultrashort, high-intensity laser installation at the Intense Laser Irradiation Laboratory(ILIL) including laser, beam transport and target area specifications. The laboratory was de...We present the main features of the ultrashort, high-intensity laser installation at the Intense Laser Irradiation Laboratory(ILIL) including laser, beam transport and target area specifications. The laboratory was designed to host laser–target interaction experiments of more than 220 TW peak power, in flexible focusing configurations, with ultrarelativistic intensity on the target. Specifications have been established via dedicated optical diagnostic assemblies and commissioning interaction experiments. In this paper we give a summary of laser specifications available to users,including spatial, spectral and temporal contrast features. The layout of the experimental target areas is presented, with attention to the available configurations of laser focusing geometries and diagnostics. Finally, we discuss radiation protection measures and mechanical stability of the laser focal spot on the target.展开更多
Space exploration provides unparalleled opportunities for unraveling the mysteries of our origins and exploring planetary systems beyond Earth.Long-distance space missions require successful protection against signifi...Space exploration provides unparalleled opportunities for unraveling the mysteries of our origins and exploring planetary systems beyond Earth.Long-distance space missions require successful protection against significant radiation exposure,necessitating the development of effective radiation shielding materials.This study developed aromatic amide polymer(AAP)and boron nitride nanotube(BNNT)composite fibers using lyotropic liquid crystal(LLC)and industrially viable wet-spinning processes.The uniaxially oriented 1D composite fibers provide the necessary continuity and pliability to fabricate 2D macroscopic textiles with low density(1.80 g cm-3),mechanical modulus(18.16 GPa),and heat stability(up to 479℃),while exhibiting the improved thermal neutron absorption cross-section with thermal neutron-shielding performance(0.73 mm^(-1)).These composite textiles also show high thermal conductivity(7.88 W m^(-1)K^(-1))due to their densely packed and uniaxially oriented structures.These enhanced characteristics render the fibers a highly promising material for space applications,offering robust protection for both astronauts and electronics against the dual threats of radiation and heat.展开更多
Background The Circular Election–Positron Collider has been proposed by Institute of High Energy Physics(IHEP,CAS).The beam in the main ring with energy up to 120 GeV would produce intense synchrotron radiation(SR)wi...Background The Circular Election–Positron Collider has been proposed by Institute of High Energy Physics(IHEP,CAS).The beam in the main ring with energy up to 120 GeV would produce intense synchrotron radiation(SR)with photon energy up to several MeV.Without shielding,this radiation would be harmful to the accelerator components.Purpose To clarify the radiation damage,analyze the source of SR,and design the shielding system to protect the accelerator.Methods The theoretical formula has been used to estimate the spectrum and distribution of SR.Several ways of designing or shielding vacuum chamber with different geometries and various materials are put forward to protect sensitive facility components.The Monte Carlo program FLUKA has been introduced to calculate cumulative dose and heat deposition in all designing cases.Results The SR in CEPC main ring would be harmful to the coil used in dipole magnets.The design based on LEP with aluminum and lead would need 23 mm lead to make the coil safe.The design based on LEP with copper would need 28 mm of outer copper.And the copper chamber and lead shield design would need 16 mm of Lead.Conclusion The theoretical formula has been used in source generation of Monte Carlo program to get the distribution of SR in CEPC main ring.The program was also used to simulate SR problems in the vacuum chamber with designs of different geometries and materials.Among these designs,the elliptical pipe with lead shield is preferred in CEPC.展开更多
基金funded by the National Defence University of Malaysia(Grant No.UPNM/2022/GPJP/SG/3)My Brain Sc Scholarship 2023。
文摘This study explores the impact of bismuth oxide(Bi_(2)O_(3))on the optical and radiation shielding properties of transparent,lead-free thulium-doped bismuth borotellurite radiation shielding glass.The investigated glass composition follows the formula[(TeO_(2))_(75)(B_(2)O_(3))_(25)]_(98-x)(Bi_(2)O_(3))_x[Tm_(2)O_(3)]_(2),where x=0 mol%,5 mol%,10 mol%,15 mol%,20 mol%,25 mol%,and 30 mol%.All glass samples remain transparent,with an optical bandgap(E_(opt))exceeding 3.1 e V,ensuring visible light transmission.Radiation shielding data from Phy-X and XCom reveal interactions of the photoelectric effect,Compton scattering,and pair production,with minimal relative difference in mass attenuation coefficient(MAC)which is between0.05 and 0.56.At 0.662 Me V photon energy,the 20 mol%and 25 mol%Bi_(2)O_(3)glasses exhibit significantly higher Phy-X MAC values than other samples,except RS 520 glass,which contains 71%Pb O.Despite incorporating only up to 25 mol%Bi_(2)O_(3),these glasses outperform others in density,half-value layer(HVL),and mean free path(MFP).Correlating E_(opt)and MAC,the 20 mol%Bi_(2)O_(3)glass is the best candidate for transparent radiation shielding glass due to its wide optical bandgap which prevents ionization of trapped holes.Significantly,the linkage between MFP and molar refraction was also discovered based on the particle size influence on both parameters.
基金Project(14JJ2083)supported by the Natural Science Foundation of Hunan Province,ChinaProject(2015JC3090)supported by the Science and Technology Department of Hunan Province,China
文摘The recycled cathode ray tube(CRT)funnel glass was used as replacement of magnetite sand in the concrete,and its mass replacement rates were 0,20%,40%and 60%,respectively.The flowability,apparent density and mechanical properties of the radiation shielding concrete were investigated,while itsγ-ray radiation shielding parameters such as linear and mass attenuation coefficients(μandμm,respectively),thickness values of half-value layer(hHVL)and tenth-value layer(hTVL)were obtained by theoretical calculation,experiment and Monte.Carlo N-Particle(MCNP)simulation code.The experimental results show that the flowability of the concrete increases significantly,whilst its apparent density,compressive strength and static elastic modulus decrease slightly.The calculated,simulated and experimentalμm,μ,hHVL and hTVL values of all concrete samples are very consistent at the sameγ-ray photon energy,and it is feasible to use MCNP code to simulateγ-ray radiation shielding parameters of materials.The calculated results show that in a wide range ofγ-ray photon energy,theμm value of the concrete with CRT funnel glass replacing magnetite sand is improved effectively,and its radiation shielding performances are the same as those of the control concrete(M.1).By comprehensively comparing the flowability,mechanical properties andγ-ray radiation shielding properties,the concrete samples with 20%.40%funnel glass as fine aggregate have good performances.
基金partially supported by the China Postdoctoral Science Foundation(No.2019M650611)
文摘A synchrotron-based proton therapy(PT)facility that conforms with the requirement of future development trend in compact PT can be operated without an energy selection system.This article demonstrates a novel radiation shielding design for this purpose.Various FLUKAbased Monte Carlo simulations have been performed to validate its feasibility.In this design,two different shielding scenarios(3-m-thick concrete and 2-m-thick iron–concrete)are proved able to reduce the public annual dose to the limit of 0.1 mSv/year.The calculation result shows that the non-primary radiation from a PT system without an inner shielding wall complies with the IEC 60601-2-64 international standard,making a single room a reality.Moreover,the H/D value of this design decreases from 2.14 to 0.32 mSv/Gy when the distance ranges from 50 to 150 cm from the isocenter,which is consistent with the previous result from another study.By establishing a typical time schedule and procedures in a treatment day for a single room in the simulation,a non-urgent machine maintenance time of 10 min after treatment is recommended,and the residual radiation level in most areas can be reduced to 2.5 lSv/h.The annual dose for radiation therapists coming from the residual radiation is 1 mSv,which is 20%of the target design.In general,this shielding design ensures a low cost and compact facility compared with the cyclotron-based PT system.
基金financially supported by the National Natural Science Foundation of China(No.51772275 and No.51972089)Distinguished Young Foundation of Henan Province(No.202300410355)。
文摘With continuous enhancement of gas-turbine inlet temperature and rapid increase of radiant heat transfer,thermal barrier coating(TBC)materials with a combination of low thermal conductivity and good high-temperature thermal radiation shielding performance play vital roles in ensuring the durability of metallic blades.However,yttria-stabilized zirconia(YSZ),as the state-of-the-art TBC and current industry standard,is unable to meet such demands since it is almost translucent to high-temperature thermal radiation.Besides,poor corrosion resistance of YSZ to molten calcia-magnesia-alumina-silicates(CMAS)also impedes its application in sand,dust,or volcanic ash laden environments.In order to improve the hightemperature thermal radiation shielding performance and CMAS resistance of YSZ and further reduce its thermal conductivity,two medium-entropy(ME)oxide ceramics,ME(Y,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)and ME(Ta,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2),were designed and prepared by pressureless sintering of binary powder compacts in this work.ME(Y,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)presents cubic structure but a trace amount of secondary phase,while ME(Ta,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)displays a combination of tetragonal phase(81.6 wt.%)and cubic phase(18.4 wt.%).Both ME(Y,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)and ME(Ta,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)possess better high-temperature thermal radiation shielding performance than YSZ.Especially,the high-temperature thermal radiation shielding performance of ME(Ta,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)is superior to that of ME(Y,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)due to its narrower band gap and correspondingly higher infrared absorbance(above 0.7)at the waveband of 1 to 5μm.The two ME oxides also display significantly lower thermal conductivity than YSZ and close thermal expansion coefficients(TECs)to YSZ and Ni-based superalloys.In addition,the two ME oxides possess excellent CMAS resistance.After attack by molten CMAS at 1250℃for 4 h,merely~2μm thick penetration layer has been formed and the structure below the penetration layer is still intact.These results demonstrate that ME(Me,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2)(Me=Y and Ta),especially ME(Ta,Ti)_(0.1)(Zr,Hf,Ce)_(0.9)O_(2),are promising thermal barrier materials for high-temperature thermal radiation shielding and CMAS blocking.
基金Funded by the National Natural Science Foundation of China(No.51272192)National "Twelfth Five-Year" Plan for Science&Technology Support(No.2011BAJ04B05-02)
文摘A new method to prepare radiation shielding functional aggregate is described, and an appropriate mix ratio and a reasonable calcinated condition was engaged. The y-ray shielding capability of both the new functional aggregates and some other nature aggregates had been measured. The linear attenuation coefficients （μ, cm-1） of these aggregates had been calculated at photon energies from 1 keV to 10GeV using XCOM program, and measured at the photon energies of 662 keV, showing good agreement between experimental and calculated results. The results show that the y-ray shielding capacity of the new functional aggregates has been improved substantially compared with basalt, almost equal to serpentine and high-titanium slag, and up to 80% to barite.
文摘The radiation shielding characteristics of 50wt% WO3/E44 epoxy composite in various gamma energies from 80 keV to 1.33 MeV are investigated via the MCNP code. Thus two scales are considered for WOa filler particles： micro and nano with sizes of i #m and 5Onto, respectively. The simulation results show that W03 nano particles exhibit a larger increase in linear attenuation coefficient in comparison with micro size particles. Finally, validation of simulation results with the published experimental data shows a good agreement.
文摘Heavy concrete currently used for construction contains special materials that are expensive and difficult to work with.This study replaced natural aggregate（stones） in concrete with round steel balls,which are inexpensive and easily obtainable.The diameters of the steel balls were 0.5 and 1 cm,and their density was 7.8 kg/m3.Dense packing mixture methods were used to produce heavy concrete with densities of 3500 and 5000 kg/m3.The various properties of this concrete were tested according to the standards of the American Society for Testing and Materials（ASTM）.The results indicated that the construction slump of the concrete could reach 260-280 mm and its slump flow could reach 610-710 mm.More important,its compressive strength could reach 8848 MPa.These results will significantly alter traditional construction methods that use heavy concrete and enhance innovative ideas for structural design.
基金financially supported by the Meteorological Key Technology Integration and Application Project funded by the China Meteorological Administration (Grant No.CAMGJ2012M01)the Special Fund of Beijing Meteorological Bureau (Grant No.2011BMBKYZX04)the Nation Natural Science Foundation of China (Grant No.41275114)
文摘The variation of air temperature measurement errors using two different radiation shields （DTR502B Vaisala,Finland,and HYTFZ01,Huayun Tongda Satcom,China） was studied.Datasets were collected in the field at the Daxing weather station in Beijing from June 2011 to May 2012.Most air temperature values obtained with these two commonly used radiation shields were lower than the reference records obtained with the new Fiber Reinforced Polymers （FRP） Stevenson screen.In most cases,the air temperature errors when using the two devices were smaller on overcast and rainy days than on sunny days; and smaller when using the imported rather than the Chinese shield.The measured errors changed sharply at sunrise and sunset,and reached maxima at noon.Their diurnal variation characteristics were,naturally,related to changes in solar radiation.The relationships between the record errors,global radiation,and wind speed were nonlinear.An improved correction method was proposed based on the approach described by Nakamura and Mahrt （2005） （NM05）,in which the impact of the solar zenith angle （SZA） on the temperature error is considered and extreme errors due to changes in SZA can be corrected effectively.Measurement errors were reduced significantly after correction by either method for both shields.The error reduction rate using the improved correction method for the Chinese and imported shields were 3.3％ and 40.4％ higher than those using the NM05 method,respectively.
文摘Purpose The High Energy Photon Source(HEPS)is currently under construction in China and will be the brightest synchrotron radiation facility in the world.To solve the gas bremsstrahlung and synchrotron radiation hazard at HEPS beamlines,a comprehensive radiation study is performed.Method The Monte Carlo method is used to analyze the radiation field in the first optics enclosure at HEPS beamlines.First,the radiation sources including gas bremsstrahlung and synchrotron radiation are estimated.Then,the distribution of the radiation field in the hutch is calculated.Conservative parameters and a typical beamline geometry are used in the calculations.Finally,the shielding recommendations are summarized.Results and Conclusion In this paper,the considerations and bulk shielding design of the first optics enclosure at HEPS beamlines are described.The design satisfies the requirements of the radiation safety principles.
基金supported by the National Natural Science Foundation of China(grant no.52192603,52275308).
文摘A novel lightweight,radiation-shielding Mg-Ta-Al layered metal-matrix composite(LMC)was successful designed by doping the extremely refractory metal(Ta)into Mg sheets.These Mg-based LMCs sheets shows excellent radiation-dose shield effect,about 145 krad·a^(−1),which is about 17 times of traditional Mg alloy,while its surface density is only about 0.9 g·cm^(−2),reducing by 60%than that of pure Ta.The quantitate relationship between radiation-dose and the materials’thickness was also confirmed to the logistic function when the surface density is in the range of 0.6-1.5 g·cm^(−2).Meantime,the rolling parameters,interface microstructure and mechanical properties in both as-rolled and annealing treated samples were evaluated.The sheets possess a special dissimilar atoms diffusion transitional zone containing an obvious inter-diffusion Mg-Al interface and the unique micro-corrugated Ta-Al interface,as well as a thin Al film with a thickness of about 10μm.The special zone could reduce the stress concentration and enhance the strength of Mg-Ta-Al LMCs.The interface bonding strength reaches up to 54-76 MPa.The ultimate tensile strength(UTS)and yield strength(TYS)of the Mg-Ta-Al sheet were high to 413 MPa and 263 MPa,respectively,along with an elongation of 5.8%.The molecular dynamics(MD)analysis results show that the two interfaces exhibit different formation mechanism,the Mg-Al interface primarily depended on Mg/Al atoms diffusion basing point defects movement,while the Ta-Al interface with a micro-interlock pining shape formed by close-packed planes slipping during high temperature strain-induced deformation process.
基金supported by the National Natural Science Foundation of China(Grant Nos.41771423,41930102,41601408 and 41491339)the industry-university-research cooperation project for the social development of Fujian province,China(grant number 2018Y0054)
文摘Solar radiation is often shielded by terrain relief,especially in mountainous areas,before reaching the surface of the Earth.The objective of this paper is to study the spatial structures of the shielded astronomical solar radiation(SASR)and the possible sunshine duration(PSD)over the Loess Plateau.To this end,we chose six test areas representing different landforms over the Loess Plateau and the software package of Matlab was used as the main computing platform.In each test area,5-m-resolution digital elevation model established from 1:10,000 scale topographic maps was used to compute the corresponding slope,SASR and PSD.Then,we defined the concepts of the slope-mean SASR spectrum and the slope-mean PSD spectrum,and proposed a method to extract them from the computed slope,SASR and PSD over rectangular analysis windows.Using this method,we found both spectrums in a year or in a season for each of the four seasons in the six test areas.Each spectrum was found only when the area of the corresponding rectangular analysis window was greater than the corresponding stable area of the spectrum.The values of the two spectrums decreased when the slope increased.Furthermore,the values of the stable areas of the spectrums in a year or in a season were positively correlated with the variable coefficients of the slope or the profile curvature.The values of the stable areas of the two spectrums in a year or in a season may represent the minimum value of test areas for corresponding future research on the spatial structures of the SASR or PSD.All the findings herein suggest that the spatial structures of the PSD and the SASR are caused by the interactions between solar radiation and terrain relief and that the method for extracting either spectrum is effective for detecting their spatial structures.This study may deepen our understanding of the spatial structure of solar radiation and help us further explore the distribution of solar energy in mountainous regions.
文摘The radiation generated by nuclear reaction is harmful to human body and equipment,thus the radiation shielding materials that employ the shielding ability from neutron and gamma rays are the best candidates according to application situations and radiation sources.In this paper,the researches of metal-based neutron and gamma rays or multiple purpose shielding materials are systematically summarized,and the respective and principal problems of these materials with respect to shielding effectiveness and other performances,such as corrosion,mechanical properties,manufacture,etc.,are discussed.Finally,the prospect of shielding materials is outlined,which suggests that the development of highly efficient and multiply functional radiation shielding materials with good environmental compatibility is one of the future development trends.
文摘The 52%energy of the solar radiation is contributed by near-infrared radiation(NIR,780-2500 nm).Therefore,the material design for the energy-saving smart window,which can effectively shield NIR and has acceptable visible transmittance,is vital to save the energy consumed on the temperature control system.It is important to find a non-toxic stable material with excellent NIR-shielding ability and acceptable visible transmittance.The systematic first-principles study on Li_(x)Sn_(y)WO_(3)(x=0,0.33,0.66,and y=0,0.33)exhibits that the chemical stability is a positive correlation with the doping concentration.After doping,the Fermi-energy upshifts into the conduction band,and the material shows metal-like characteristics.Therefore,these structures Li_(x)Sn_(y)WO_(3)(except the structure with x=0.33 and y=0)show pronounced improvement of NIR shielding ability.Our results indicate that when x=0 and y=0.33,the material exhibits the strongest NIR-shielding ability,satisfying chemical stability,wide NIR-shielding range(780-2500 nm),and acceptable visible transmittance.This work provides a good choice for experimental study on NIR shielding material for the energy-saving window.
基金Youth Innovation Promotion Association of the Chinese Academy of Sciences,2020015,Xiang He
文摘Purpose The research focuses on the related measurement and shielding works for solving the spatial electromagnetic radiation and interference problems of the BEPCⅡLinac.Methods The radiation frequency and intensity can be determined by using a set of antennas connected with a spectrum analyser.Results The source of the radiation is located on the cable connectors of some device panels.The radiation intensity is significantly reduced after wrapping the connectors with the radiation shielding tape.Conclusions The entire research process includes the selection of a domestically made ultra-wideband antenna,the proposal of the measurement methods,the locating of the radiation source,the performance measurement of the radiation shielding tape and the shielding of the radiation.It provides a whole set of feasible solutions for similar problems in accelerators.
基金supported by National Key Research and Development Program of China,China(grant no.2023YFB3812000)National Natural Science Foundation of China,China(U21A20441)Science and Technology Project of Sichuan Province,China(2023ZYD0137).
文摘Nuclear power is essential for sustainable energy infrastructure and economic development,necessitating materials for high-radiation environments that can facilitate visualization and observation.Conventional lead glass is inadequate for future requirements due to radiation-induced darkening,poor mechanical properties,and toxicity.Therefore,there is urgent to find new window materials that offer multi-ionization shielding(particularly against deep-penetrating gamma ray,γ,and neutron,n,radiations),desirable opto-mechanical properties,service stability against darkening,and non-toxicity.In this study,we report a family of transparent rare-earth pyrochlore ceramics La_(x)Gd_(2-x)Zr_(2)O_(7),offering unique chemo-physical properties that are ideal for robust radiation shielding windows.Remarkably,we demonstrated the capability of maintaining high transparency under heavy-dose exposure to 1000 kGy ^(60)Coγradiation.We observed the service stability against radiation darkening can be greatly enhanced with La-rich compositions,while Gd-rich compositions undergo shallow darkening that can be reversibly recovered under visible light.This behavior is attributed to mitigated oxygen migration from 48f to 8a in La-rich compositions,which have high pyrochlore phase stability and well-ordered atomic structures,and reversible oxygen migration between 48f and 8a in Gd-rich compositions,which remain active at room temperature.Our proposal and demonstration unlock ample opportunities in designing functional transparent ceramics as window materials for demanding applications in high-radiation environments.
文摘This study investigated the characteristics of bremsstrahlung and induced neutrons from the elec- tron storage ring in the Shanghai Synchrotron Radiation Facility (SSRF).The EGSnrc and MCNP Monte Carlo code has been used to perform the assess neutron and photon dose profiles for a variety of shield ma- terials ranging from 5 to 115cm thick.The Monte Carlo simulations show that single material such as lead, iron and polyethylene have been found to be ineffective biological shield materials,while the mixed materials serve as effective shields for shielding high energy neutron.Mixed materials such as lead or iron combined with polyethylene or with concrete are good materials combination for high energy neutron radiation shield.And high-Z materials such as lead or iron combine with low-Z material containing some hydrogen such polyethylene are effective for shielding high energy neutrons as well as bremsstrahlung.
基金Thiswork is supported by the high-energy photon source(HEPS)project,a major national science and technology infrastructure.
文摘Purpose The high-energy photon source(HEPS)is the first fourth-generation light source under construction in China.It is designed to operate at an average current of 200 mA stored beam current with a top-up model at 6 GeV energy.Considering the linac radiation shielding design,a suitable beam loss scenario,optimized thickness for the bulk shielding and detailed structure design for dumps should be proposed.In this paper,the beam loss scenarios were determined and categorized as normal;the dose limits were presented;using these scenarios and the dose limits,the thickness of the linac tunnel was calculated and detailed designs of the main beam dumps were established.The material selection and size setting of the low-power electron beam dump were discussed.Method The Monte Carlo code is a good choice to simulate the radiation analysis.And the iSHIELD11 was used to verify the simulation calculations.Result and conclusion The designs of the linac bulk shield and dumps satisfied the requirements of radiation protection.
基金The ILIL-PW upgrade was established in the framework of the Italian Research Network on Extreme Light Infrastructure(ELI-Italy)funded by CNRfinancial contribution from the Eu PRAXIA project of the EU Horizon 2020 Research and Innovation Program under Grant Agreement No.653782the Line for Laser Light Ion Acceleration(L3IA)project funded by INFN,Italy。
文摘We present the main features of the ultrashort, high-intensity laser installation at the Intense Laser Irradiation Laboratory(ILIL) including laser, beam transport and target area specifications. The laboratory was designed to host laser–target interaction experiments of more than 220 TW peak power, in flexible focusing configurations, with ultrarelativistic intensity on the target. Specifications have been established via dedicated optical diagnostic assemblies and commissioning interaction experiments. In this paper we give a summary of laser specifications available to users,including spatial, spectral and temporal contrast features. The layout of the experimental target areas is presented, with attention to the available configurations of laser focusing geometries and diagnostics. Finally, we discuss radiation protection measures and mechanical stability of the laser focal spot on the target.
基金supported by the Korea Institute of Science and Technology(KIST)K-Lab Program,in addition to grants from the Mid-Career Researcher Program(2021R1A2C2009423)the Ministry of Trade,Industry&Energy(MOTIE RS-2023-00258591)the Korea Research Institute for Defense Technology Planning and Advancement(DAPA KRIT-CT-21-014).
文摘Space exploration provides unparalleled opportunities for unraveling the mysteries of our origins and exploring planetary systems beyond Earth.Long-distance space missions require successful protection against significant radiation exposure,necessitating the development of effective radiation shielding materials.This study developed aromatic amide polymer(AAP)and boron nitride nanotube(BNNT)composite fibers using lyotropic liquid crystal(LLC)and industrially viable wet-spinning processes.The uniaxially oriented 1D composite fibers provide the necessary continuity and pliability to fabricate 2D macroscopic textiles with low density(1.80 g cm-3),mechanical modulus(18.16 GPa),and heat stability(up to 479℃),while exhibiting the improved thermal neutron absorption cross-section with thermal neutron-shielding performance(0.73 mm^(-1)).These composite textiles also show high thermal conductivity(7.88 W m^(-1)K^(-1))due to their densely packed and uniaxially oriented structures.These enhanced characteristics render the fibers a highly promising material for space applications,offering robust protection for both astronauts and electronics against the dual threats of radiation and heat.
文摘Background The Circular Election–Positron Collider has been proposed by Institute of High Energy Physics(IHEP,CAS).The beam in the main ring with energy up to 120 GeV would produce intense synchrotron radiation(SR)with photon energy up to several MeV.Without shielding,this radiation would be harmful to the accelerator components.Purpose To clarify the radiation damage,analyze the source of SR,and design the shielding system to protect the accelerator.Methods The theoretical formula has been used to estimate the spectrum and distribution of SR.Several ways of designing or shielding vacuum chamber with different geometries and various materials are put forward to protect sensitive facility components.The Monte Carlo program FLUKA has been introduced to calculate cumulative dose and heat deposition in all designing cases.Results The SR in CEPC main ring would be harmful to the coil used in dipole magnets.The design based on LEP with aluminum and lead would need 23 mm lead to make the coil safe.The design based on LEP with copper would need 28 mm of outer copper.And the copper chamber and lead shield design would need 16 mm of Lead.Conclusion The theoretical formula has been used in source generation of Monte Carlo program to get the distribution of SR in CEPC main ring.The program was also used to simulate SR problems in the vacuum chamber with designs of different geometries and materials.Among these designs,the elliptical pipe with lead shield is preferred in CEPC.
