The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 3...The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.展开更多
The solidification of Sn-Ni peritectic alloys in which both the primary Ni_(3)Sn_(2)and peritectic Ni_(3)Sn_(4)phases were intermetallic compound phases(IMCs)with narrow solubility ranges was investigated through conf...The solidification of Sn-Ni peritectic alloys in which both the primary Ni_(3)Sn_(2)and peritectic Ni_(3)Sn_(4)phases were intermetallic compound phases(IMCs)with narrow solubility ranges was investigated through confocal laser scanning microscope.Analysis on the interface migration at different cooling rates shows that the rate of peritectic reaction is much smaller than previous reports,and the growth of peritectic phase is mainly attributed to direct precipitation from the melt in Sn-Ni alloy after peritectic reaction.In addition,different from other peritectic alloys where the solidified phases are solid solution phases,the"step"growth of both Ni_(3)Sn_(2)and Ni_(3)Sn_(4)phases was observed.The dependences of the step thickness on both the cooling rate and solidification time were measured,which shows that the step thicknesses of both phases gradually decrease as solidification proceeds.This was confirmed to be attributed to the difference between the actual and equilibrium melt concentrations during solidification.In addition,the increase of the normal growth velocity of Ni_(3)Sn_(4)phase with increasing cooling rate was also proved through both the experimental observation and quantitative prediction.展开更多
Compared with the growing applications of peritectic alloy,none research on the freckle formation during peritectic solidification has been reported before.Observation on the dendritic mushy zone of Sn-36 at.%Ni perit...Compared with the growing applications of peritectic alloy,none research on the freckle formation during peritectic solidification has been reported before.Observation on the dendritic mushy zone of Sn-36 at.%Ni peritectic alloy during directional solidification at different growth velocities shows that the freckles are formed in two different regions:region I before peritectic reaction and region II after peritectic reaction.In addition,more freckles can be observed at lower growth velocities.Examination on the experimental results demonstrates that both the temperature gradient zone melting(TGZM)and Gibbs-Thomson(G–T)effects have obvious influences on the morphology of dendritic network during directional solidification.The current theories onKI Rayleigh number Racharacterizing the thermosolutal convection of dendritic mushy zone to predict freckle formation through the maximum of Ra can only explain the existence of region I while the appearance of region II after peritectic reaction cannot be predicted.Thus,a new Rayleigh number RaP is proposed in consideration of evolution of dendritic mushy zone by both effects and peritectic reaction.Theoretical prediction of RaPalso shows a maximum after peritectic reaction in addition to that before peritectic reaction,thus,agreeing well with the freckle formation in region II.In addition,more severe thermosolutal convection can be predicted by the new Rayleigh number RaP at lower growth velocities,which further demonstrates the reliability of RaP in describing the dependence of freckle formation on growth velocity.展开更多
1.Introduction Dendritic structure are commonly encountered during solidification[1-4],especially in systems freezing with relatively low entropies of transformation[1,5].Generally speaking,the dendritic structure is ...1.Introduction Dendritic structure are commonly encountered during solidification[1-4],especially in systems freezing with relatively low entropies of transformation[1,5].Generally speaking,the dendritic structure is composed of primary dendrite stem,secondary branch and even tertiary and higher order dendrite arms[1].Different kinds of models have been proposed for describing the growth of primary dendrite[1-5]and secondary dendrite arms[1,6,7].展开更多
Compared with the growing applications of peritectic alloys,none research on the fluid permeability K of dendritic network during peritectic solidification has been reported before.The fluid permeability K of dendriti...Compared with the growing applications of peritectic alloys,none research on the fluid permeability K of dendritic network during peritectic solidification has been reported before.The fluid permeability K of dendritic network in the mushy zone during directional solidification of Sn-Ni peritectic alloy was investigated in this study.Examination on the experimental results demonstrates that both the temperature gradient zone melting(TGZM)and Gibbs-Thomson(G–T)effects have obvious influences on the morphology of dendritic network during directional solidification.This is realized through different stages of liquid diffusion within dendritic mushy zone by these effects during directional solidification.The TGZM effect is demonstrated to play a more important role as compared with the G–T effect during directional solidification.Besides,it is shown that the evolution of dendrite network is more complex during peritectic solidification due to the involvement of the peritectic phase.Through the specific surface SV,analytical expression based on the Carman–Kozeny model was proposed to analyze the fluid permeability of dendritic mushy zone in directionally solidified peritectic alloys.In addition,it is interesting to find a rise in permeability K after peritectic reaction in both theoretical predication and experimental results,which is different from that in other alloys.The theoretical predictions show that this rise in fluid permeability K after peritectic reaction is caused by the remelting/resolidification process on dendritic structure by the TGZM and G–T effects during peritectic solidification.展开更多
基金support from diverse funding sources,including the National Key Program for S&T Research and Development of the Ministry of Science and Technology(MOST),Yifang Wang's Science Studio of the Ten Thousand Talents Project,the CAS Key Foreign Cooperation Grant,the National Natural Science Foundation of China(NSFC)Beijing Municipal Science&Technology Commission,the CAS Focused Science Grant,the IHEP Innovation Grant,the CAS Lead Special Training Programthe CAS Center for Excellence in Particle Physics,the CAS International Partnership Program,and the CAS/SAFEA International Partnership Program for Creative Research Teams.
文摘The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.
基金financially supported by the National Natural Science Foundation of China(No.51871118)the Fundamental Research Funds for the Central Universities(No.lzujbky-2019-sp03)the fund of Science and Technology Project of Lanzhou(No.2019-1-30)。
文摘The solidification of Sn-Ni peritectic alloys in which both the primary Ni_(3)Sn_(2)and peritectic Ni_(3)Sn_(4)phases were intermetallic compound phases(IMCs)with narrow solubility ranges was investigated through confocal laser scanning microscope.Analysis on the interface migration at different cooling rates shows that the rate of peritectic reaction is much smaller than previous reports,and the growth of peritectic phase is mainly attributed to direct precipitation from the melt in Sn-Ni alloy after peritectic reaction.In addition,different from other peritectic alloys where the solidified phases are solid solution phases,the"step"growth of both Ni_(3)Sn_(2)and Ni_(3)Sn_(4)phases was observed.The dependences of the step thickness on both the cooling rate and solidification time were measured,which shows that the step thicknesses of both phases gradually decrease as solidification proceeds.This was confirmed to be attributed to the difference between the actual and equilibrium melt concentrations during solidification.In addition,the increase of the normal growth velocity of Ni_(3)Sn_(4)phase with increasing cooling rate was also proved through both the experimental observation and quantitative prediction.
基金financially supported by the National Natural Science Foundation of China(No.51871118)the 2018 joint Foundation of Ministry of Education for Equipment Pre-research(No.6141A020332)+3 种基金the Key Research and Development Plan of Gansu Province(No.18YF1GA102)the Fundamentalx Research Funds for the Central Universities(No.lzujbky-2019-sp03)the Fund of Science and Technology Project of Lanzhou City(No.2019-1-30)the Fund of State Key Laboratory of Special Rare Metal Materials(No.SKL2020K003)。
文摘Compared with the growing applications of peritectic alloy,none research on the freckle formation during peritectic solidification has been reported before.Observation on the dendritic mushy zone of Sn-36 at.%Ni peritectic alloy during directional solidification at different growth velocities shows that the freckles are formed in two different regions:region I before peritectic reaction and region II after peritectic reaction.In addition,more freckles can be observed at lower growth velocities.Examination on the experimental results demonstrates that both the temperature gradient zone melting(TGZM)and Gibbs-Thomson(G–T)effects have obvious influences on the morphology of dendritic network during directional solidification.The current theories onKI Rayleigh number Racharacterizing the thermosolutal convection of dendritic mushy zone to predict freckle formation through the maximum of Ra can only explain the existence of region I while the appearance of region II after peritectic reaction cannot be predicted.Thus,a new Rayleigh number RaP is proposed in consideration of evolution of dendritic mushy zone by both effects and peritectic reaction.Theoretical prediction of RaPalso shows a maximum after peritectic reaction in addition to that before peritectic reaction,thus,agreeing well with the freckle formation in region II.In addition,more severe thermosolutal convection can be predicted by the new Rayleigh number RaP at lower growth velocities,which further demonstrates the reliability of RaP in describing the dependence of freckle formation on growth velocity.
基金financially supported by the National Natural Science Foundation of China(No.51871118)the 2018 joint Foundation of Ministry of Education for Equipment Pre-research(No.6141A020332)+3 种基金the Key Research and Development Plan of Gansu Province(No.18YF1GA102)the Fundamental Research Funds for the Central Universities(No.lzujbky-2019-sp03)the Fund of Science and Technology Project of Lanzhou City(No.2019-1-30)the Fund of State Key Laboratory of Special Rare Metal Materials(No.SKL2020K003)。
文摘1.Introduction Dendritic structure are commonly encountered during solidification[1-4],especially in systems freezing with relatively low entropies of transformation[1,5].Generally speaking,the dendritic structure is composed of primary dendrite stem,secondary branch and even tertiary and higher order dendrite arms[1].Different kinds of models have been proposed for describing the growth of primary dendrite[1-5]and secondary dendrite arms[1,6,7].
基金financially supported by the project from the Natural Science Foundation of China(No.51871118)the 2018 Joint Foundation of Ministry of Education for Equipment Pre-research(No.6141A020332)+3 种基金the Key Research and Development Plan of Gansu Province(No.18YF1GA102)the Fundamental Research Funds for the Central Universities(No.lzujbky-2019-sp03)the fund of Science and Technology Project of Lanzhou City(No.2019-1-30)the fund of State Key Laboratory of Special Rare Metal Materials(No.SKL2020K003)。
文摘Compared with the growing applications of peritectic alloys,none research on the fluid permeability K of dendritic network during peritectic solidification has been reported before.The fluid permeability K of dendritic network in the mushy zone during directional solidification of Sn-Ni peritectic alloy was investigated in this study.Examination on the experimental results demonstrates that both the temperature gradient zone melting(TGZM)and Gibbs-Thomson(G–T)effects have obvious influences on the morphology of dendritic network during directional solidification.This is realized through different stages of liquid diffusion within dendritic mushy zone by these effects during directional solidification.The TGZM effect is demonstrated to play a more important role as compared with the G–T effect during directional solidification.Besides,it is shown that the evolution of dendrite network is more complex during peritectic solidification due to the involvement of the peritectic phase.Through the specific surface SV,analytical expression based on the Carman–Kozeny model was proposed to analyze the fluid permeability of dendritic mushy zone in directionally solidified peritectic alloys.In addition,it is interesting to find a rise in permeability K after peritectic reaction in both theoretical predication and experimental results,which is different from that in other alloys.The theoretical predictions show that this rise in fluid permeability K after peritectic reaction is caused by the remelting/resolidification process on dendritic structure by the TGZM and G–T effects during peritectic solidification.
