The Circular Electron Positron Collider(CEPC)proposed in China is a dual-ring collider with electron and positron beams in the energy range of 45.5–180 GeV.The main dipole in the CEPC collider is a dual-aperture dipo...The Circular Electron Positron Collider(CEPC)proposed in China is a dual-ring collider with electron and positron beams in the energy range of 45.5–180 GeV.The main dipole in the CEPC collider is a dual-aperture dipole with a shared coil between the two apertures,forming an I-shaped structure that can reduce power consumption by 50%.Because of its long length and low field strength,the development of this dual-aperture magnet faces challenges regarding its mechanical design,field measurement accuracy,and field performance.Numerical simulations were performed to better understand the Earth's field and the effect of different BH curves on field performance.The field results of the prototype are presented herein,and the field quality satisfies the requirements.The remanent field accounts for 2%of the integral field at 140 Gs,and the hysteresis effect caused an increase in field strength of approximately 0.075%after a standardization cycle of the trim coils.Research on this prototype can provide useful insights for understanding low-field dipole magnets.展开更多
To reduce the energy demand and operation cost for circular electron positron collider(CEPC), the high efficiency klystrons are being developed at Institute of High Energy Physics, Chinese Academy of Sciences. A 800-k...To reduce the energy demand and operation cost for circular electron positron collider(CEPC), the high efficiency klystrons are being developed at Institute of High Energy Physics, Chinese Academy of Sciences. A 800-k W continuous wave(CW) klystron operating at frequency of 650-MHz has been designed. The results of beam–wave interaction simulation with several different codes are presented. The efficiency is optimized to be 65% with a second harmonic cavity in three-dimensional(3D) particle-in-cell code CST. The effect of cavity frequency error and mismatch load on efficiency of klystron have been investigated. The design and cold test of reentrant cavities are described, which meet the requirements of RF section design. So far, the manufacturing and high-power test of the first klystron prototype have been completed.When the gun operated at DC voltage of 80 k V and current of 15.4 A, the klystron peak power reached 804 k W with output efficiency of about 65.3% at 40% duty cycle. The 1-d B bandwidth is ±0.8 MHZ. Due to the crack of ceramic window, the CW power achieved about 700 kW. The high-power test results are in good agreement with 3D simulation.展开更多
Main quadrupole magnets are critical for the Circular Electron and Positron Collider(CEPC)and are specifically designed as dual aperture quadrupole(DAQ)magnets.However,the field crosstalk between the two apertures pre...Main quadrupole magnets are critical for the Circular Electron and Positron Collider(CEPC)and are specifically designed as dual aperture quadrupole(DAQ)magnets.However,the field crosstalk between the two apertures presents challenges.As the CEPC will work at four beam energies of Z,W,Higgs and ttbar mode,the DAQ magnets will operate at four field gradients spanning from 3.18 to 12.63 T/m.The first short quadrupole magnet prototype with the bore diameter of 76 mm and magnetic length of 1.0 m revealed the problems of large magnetic field harmonics and a magnetic center shift within the beam energy range.Accordingly,a compensation method was proposed in this work to solve the field crosstalk effect.By adjusting the gap height at the middle of the two apertures,the field harmonics and magnetic center shift are significantly reduced.After optimization,the short prototype was modified using a new scheme.The field simulations are validated from the magnetic measurement results.Further,the multipole field meets the requirements of the four beam energies.The detailed magnetic field optimization,field harmonics adjustment,and measurement results are presented herein.展开更多
Positron sources are one of the most important components of the injector of a circular electron positron collector(CEPC).The CEPC is designed as an e^(+)e^(−)collider for a Higgs factory.Its accelerator system is com...Positron sources are one of the most important components of the injector of a circular electron positron collector(CEPC).The CEPC is designed as an e^(+)e^(−)collider for a Higgs factory.Its accelerator system is composed of 100-km-long storage rings and an injector.The design goal of the positron source is to obtain positron beams with a bunch charge of 3 nC.The flux concentrator(FC)is one of the cores of the positron source.This paper reports the design,development,and measurements of an FC prototype system.The prototype includes an FC and an all-solid-state high-current pulse modulator.Preliminary tests show that the peak current on the FC can reach 15.5 kA,and the peak magnetic field can reach 6.2 T.The test results are consistent with the theoretical simulation.The FC system fulfills the requirements of the CEPC positron source as well as provides a reference for the development of similar devices both domestically and abroad.展开更多
The circular electron-positron collider(CEPC)is designed to precisely measure the properties of the Higgs boson,study electroweak interactions at the Z-boson peak,and search for new physics beyond the Standard Model.A...The circular electron-positron collider(CEPC)is designed to precisely measure the properties of the Higgs boson,study electroweak interactions at the Z-boson peak,and search for new physics beyond the Standard Model.As a component of the 4th conceptual CEPC detector,the drift chamber facilitates the measurement of charged particles.This study implemented a Geant4-based simulation and track reconstruction for the drift chamber.For the simulation,detector construction and response were implemented and added to the CEPC simulation chain.The development of track reconstruction involves track finding using the combinatorial Kalman filter method and track fitting using the tool of GenFit.Using the simulated data,the tracking performance was studied.The results showed that both the reconstruction resolution and tracking efficiency satisfied the requirements of the CEPC experiment.展开更多
随着环形正负电子对撞机(Circular Electron Positron Collider,CEPC)方案的提出,由硅光电倍增管(Silicon Photomultiplier,SiPM)和塑料闪烁体组成的读出单元作为电磁量能器的预研方案之一,逐渐成为研究热点。在探测器预研阶段需要对读...随着环形正负电子对撞机(Circular Electron Positron Collider,CEPC)方案的提出,由硅光电倍增管(Silicon Photomultiplier,SiPM)和塑料闪烁体组成的读出单元作为电磁量能器的预研方案之一,逐渐成为研究热点。在探测器预研阶段需要对读出单元性能进行充分研究,因此我们设计了一套自动化测试系统用于对读出单元进行测试、分析并改善其性能。利用DT5751波形采样插件、SiPM驱动电路板、步进电机、低压电源、继电器等完成硬件搭建,以LabVIEW为开发平台完成了软件的串行协议接口之间的通信,实现了读出单元的自动化测试,编写了相应的数据处理程序。在此基础上进行了SiPM刻度、闪烁体发光均匀性以及反射材料对光输出影响的研究。测试结果表明,ESR反射膜包裹的塑闪条具有最高的光输出,塑闪条耦合10μm像素SiPM的光输出为耦合25μm像素SiPM的三分之一。展开更多
束流垃圾桶的材料、结构、尺寸的正确设计对于确保高能环形对撞机(Circular Electron Positron Collider,CEPC)直线加速器的安全运行有重要意义。采用蒙特卡罗程序FLUKA,研究了概念设计阶段的CEPC直线加速器束流垃圾桶的初步设计方案,...束流垃圾桶的材料、结构、尺寸的正确设计对于确保高能环形对撞机(Circular Electron Positron Collider,CEPC)直线加速器的安全运行有重要意义。采用蒙特卡罗程序FLUKA,研究了概念设计阶段的CEPC直线加速器束流垃圾桶的初步设计方案,给出了作为吸收体设计依据的射程的不同计算方法及验证过程,以及屏蔽体部分的材料选择与总体屏蔽厚度的关系;计算过程中引入减方差技巧提高了计算结果的精确程度。展开更多
The Circular Electron Positron Collider(CEPC)is designed to operate at key center-of-mass energies:91.2 GeV as a Z factory for precision Z boson studies,≈160 GeV at the threshold for W boson pair production,and 240 G...The Circular Electron Positron Collider(CEPC)is designed to operate at key center-of-mass energies:91.2 GeV as a Z factory for precision Z boson studies,≈160 GeV at the threshold for W boson pair production,and 240 GeV as a Higgs factory for copious Higgs boson production.It can be upgraded to 360 GeV(CEPC-360 GeV)for enabling top quark-antiquark(tt)pair production.Beyond enabling high-precision measurements of the Standard Model(SM),CEPC-360 GeV is uniquely positioned to perform searches for new physics beyond the SM(BSM),serving as a valuable complement to hadron colliders.This paper presents a sensitivity study on the direct pair production of staus and smuons at the CEPC with√s=360 GeV,conducted via full Monte Carlo simulation.Under the assumptions of 1.0 ab^(−1)integrated luminosity and a flat 5%systematic uncertainty,CEPC-360 GeV could potentially discover the combined production of left-handed and right-handed staus up to a mass of 170 GeV(if they exist)or up to 169 for pure left-handed staus and 162 GeV for pure right-handed staus.For direct smuon production,the discovery potential reaches up to 178 GeV under the same conditions.展开更多
We investigate the discovery prospects of a leptophilic gauge boson Z_(ℓ)at future e^(+)e^(-)colliders,focusing on a comparative study of the Circular Electron–Positron Collider(CEPC)and the International Linear Coll...We investigate the discovery prospects of a leptophilic gauge boson Z_(ℓ)at future e^(+)e^(-)colliders,focusing on a comparative study of the Circular Electron–Positron Collider(CEPC)and the International Linear Collider(ILC).Such a state naturally arises from an additional U(1)_(ℓ)'gauge symmetry,under which quarks remain neutral while all leptons carry a universal charge,motivated by neutrino oscillations and scenarios of physics beyond the Standard Model.As a clean benchmark,we study the process e^(+)e^(-)→μ^(+)μ^(-),including realistic effects of initial-state radiation and beamstrahlung.Our results indicate that the CEPC,with its very high luminosity at√s=240 GeV,can probe couplings down to g(ℓ)≈10^(-3)for Z_(ℓ)masses up to about 220 GeV.The ILC extends the sensitivity to heavier states in the multi-hundred GeV range through its higher√s stages.These findings demonstrate the strong complementarity of circular and linear colliders in exploring purely leptophilic interactions.展开更多
Several possible excesses around 95 GeV hint at an additional light scalar beyond the Standard Model.We examine the capability of the Circular Electron-Positron Collider(CEPC)to test this hypothesis in the Higgsstrahl...Several possible excesses around 95 GeV hint at an additional light scalar beyond the Standard Model.We examine the capability of the Circular Electron-Positron Collider(CEPC)to test this hypothesis in the Higgsstrahlung channel e^(+)e^(-)→ZS with Z→μ^(+)μ^(-)and S→τ^(+)τ^(-).A full detector simulation shows that the optimal center-of-mass energy for studying the 95 GeV light scalar is 210 GeV.A deep neural network classifier reduces the luminosity required for discovery by half.At L=20 ab^(-1),the 5σsensitivity of the CEPC to the signal strengthμ_(ττ)^(ZS)p reaches 0.016 and 0.020 for√s=210 GeV and 240 GeV,respectively.The corresponding thresholds for a 5%precision measurement areμ_(ττ)^(ZS)>0:10and>0:12.At√s=210 GeV(240 GeV),the 5σcoverage of all N2HDMFlipped samples with χ_(h_(95))^(2)<7:82requiresL=800 fb^(-1)(1.22ab^(-1)).These results establish a 210 GeV run,augmented by machine-learning selection,as the most efficient strategy to confirm or refute the 95 GeV excess at future lepton colliders.展开更多
Purpose Radio frequency power supply system is an important part of Circular Positron Collider(CEPC).S-band klystron and C-band klystron supply power.More efficient S-band and C-band klystron prototypes are planned to...Purpose Radio frequency power supply system is an important part of Circular Positron Collider(CEPC).S-band klystron and C-band klystron supply power.More efficient S-band and C-band klystron prototypes are planned to move the project forward.Methods In TDR,the klystron optimizes electron beam bunch-clustering with BAC,gains favorable RF source params via simulations&comparisons.The remaining part is mainly through debugging to obtain the best operating parameters.Results Currently,RF power supply designs for collision ring,booster ring,linear accelerator injector and damping rings are feasible.IHEP's 650 MHz,800 kW klystron reaches an efficiency target of above 80%.Beam dynamics for 2860 MHz(80 MW)and 5720 MHz(80&50 MW)klystrons are finalized and in prototyping.Conclusions Efficient klystron development is crucial for CEPC's success,ensuring energy transmission,beam stability,and promoting eco-friendly design.Current design transitions smoothly to EDR,a key milestone.It meets domestic science equipment needs,boosting localization and innovation.展开更多
1背景和动机2019年5月召开的格兰纳达(Granada)论坛是针对“The European Strategy for Particle Physics”(ESPP)所组织的研讨会,会上就国际高能物理界在希格斯粒子发现后如何推动高能物理基础研究达成了一些重要共识,特别是会议聚焦...1背景和动机2019年5月召开的格兰纳达(Granada)论坛是针对“The European Strategy for Particle Physics”(ESPP)所组织的研讨会,会上就国际高能物理界在希格斯粒子发现后如何推动高能物理基础研究达成了一些重要共识,特别是会议聚焦在将希格斯工厂作为未来对撞机的选项,并明确希格斯粒子性质的研究将是揭示隐藏在目前粒子物理标准模型后面更深层次基本规律的关键.展开更多
Purpose The purpose of this paper is to examine the carbon footprint and the environmental impact of CEPC relative to its physics reach.Methods Both a general calculation model for construction impact and the detail s...Purpose The purpose of this paper is to examine the carbon footprint and the environmental impact of CEPC relative to its physics reach.Methods Both a general calculation model for construction impact and the detail status of Chinese electric grid for operation impact has been included to examine the carbon footprint of CEPC.The same electricity carbon intensity is used when the five proposed high energy colliders are compared.Results The carbon footprint to produce a Higgs boson for CEPC has a large range from 0.34 tons(clean energy)to 2.6 tons,depending on the type of energy source used.Conclusion Focusing on Higgs physics and considering the polarization effect only for Linear colliders,CEPC was found to have the lowest carbon emission per Higgs boson at 0.34 tons of CO2 using the same clean energy(20 ton CO2 e/GWh).展开更多
Purpose The circular electron-positron collider(CEPC)is a large international scientific facility with the goal of studying the Higgs particle.In order to achieve this goal,many sophisticated detectors need to be inst...Purpose The circular electron-positron collider(CEPC)is a large international scientific facility with the goal of studying the Higgs particle.In order to achieve this goal,many sophisticated detectors need to be installed.As the basis for the installation of the internal sub-detector,the iron yoke needs to have sufficient strength and accuracy to ensure the accuracy of the internal sub-detector installation.Two different designs of CEPC detector barrel iron yoke structure are proposed.Simulation and structural optimization of these two designs are carried out,and valuable reference is provided for the subsequent design and optimization.Methods The selection of an appropriate design for the CEPC detector barrel iron yoke necessitates adherence to mechanical design requirements.In this paper,two mechanical design schemes of barrel iron yoke structure are presented,including structural design and analysis,mechanical properties analysis,dynamic properties analysis and structural optimization.Results Under the condition of 600 mm thickness,the symmetrical structure and the spiral structure are designed.The finite element analysis is used to simulate the mechanical analysis,modal analysis and seismic analysis of the two structures.Compared with the simulation results,the mechanical properties and dynamic properties of the spiral structure are better than those of the symmetrical structure under this condition.Conclusion Utilizing finite element analysis,the mechanical properties and dynamic properties of the two structures were determined.Following comparative analysis,it has been determined that the mechanical properties and dynamic properties exhibited by the spiral structure may be more in line with mechanical design requirements for the thin iron yoke structure.This study serves as a valuable reference for future design and optimization endeavors concerning the CEPC detector barrel iron yoke structure.展开更多
The Circular Electron Positron Collider(CEPC)is a large-scale particle accelerator designed to collide electrons and positrons at high energies.One of its primary goals is to achieve high-precision measurements of the...The Circular Electron Positron Collider(CEPC)is a large-scale particle accelerator designed to collide electrons and positrons at high energies.One of its primary goals is to achieve high-precision measurements of the properties of the Higgs boson and is facilitated by the large number of Higgs bosons that are produced with significantly low contamination.The measurements of Higgs boson branching fractions into bb/cc/gg andττ/WW*/ZZ*,where the W or Z bosons decay hadronically,are presented in the context of the CEPC experiment,assuming a scenario with 5600 fb^(-1)of collision data at a center-of-mass energy of 240 GeV.In this study the Higgs bosons are produced in association with a Z boson,with the Z boson decaying into a pair of muons(μ^(+)μ^(-)),which have high efficiency and resolution.To separate all decay channels simultaneously with high accuracy,the Particle Flow Network(PFN),a graph-based machine learning model,is considered.The precise classification provided by the PFN is employed in measuring the branching fractions using the migration matrix method,which accurately corrects for detector effects in each decay channel.The statistical uncertainty of the measured branching ratio is estimated to be 0.55%in the H→bb final state and approximately 1.5%-16%in the H→cc/gg/ττ/WW*/ZZ*final states.In addition,the main sources of systematic uncertainties in the measurement of the branching fractions are discussed.展开更多
Purpose Future large high-luminosity electron–positron colliders such as circular electron positron collider(CEPC)and future circular collider(FCC-ee)require nanometer-sized beams at the interaction point(IP).The lum...Purpose Future large high-luminosity electron–positron colliders such as circular electron positron collider(CEPC)and future circular collider(FCC-ee)require nanometer-sized beams at the interaction point(IP).The luminosity is very sensitive to the beam orbit drifts at the IP.It is essential to have a fast luminosity feedback system at the IP to maintain optimum beam collision conditions and prevent a luminosity degradation due to orbit drifts in the presence of mechanical vibrations and dynamical imperfections.Methods We considered two possible methods for this purpose for CEPC:one based on measurements of the luminosity and the other based on measurements of the beam orbits around the IP.Results In this paper,we present the preliminary design consideration for a fast luminosity feedback system at the IP of CEPC.展开更多
We discuss the landscape of flavor physics at the Circular Electron-Positron Collider(CEPC),based on the nominal luminosity outlined in its Technical Design Report.The CEPC is designed to operate in multiple modes to ...We discuss the landscape of flavor physics at the Circular Electron-Positron Collider(CEPC),based on the nominal luminosity outlined in its Technical Design Report.The CEPC is designed to operate in multiple modes to address a variety of tasks.At the Z pole,the expected production of 4 Tera Z bosons will provide unique and highly precise measurements of Z boson couplings,while the substantial number of boosted heavy-flavored quarks and leptons produced in clean Z decays will facilitate investigations into their flavor physics with unprecedented precision.We investigate the prospects of measuring various physics benchmarks and discuss their implications for particle theories and phenomenological models.Our studies indicate that,with its highlighted advantages and anticipated excellent detector performance,the CEPC can explore beauty andτphysics in ways that are superior to or complementary with the Belle II and Large-Hadron-Collider-beauty experiments,potentially enabling the detection of new physics at energy scales of 10 TeV and above.This potential also extends to the observation of yet-to-be-discovered rare and exotic processes,as well as testing fundamental principles such as lepton flavor universality,lepton and baryon number conservation,etc.,making the CEPC a vibrant platform for flavor physics research.The WW threshold scan,Higgs-factory operation and top-pair productions of the CEPC further enhance its merits in this regard,especially for measuring the Cabibbo-Kobayashi-Maskawa matrix elements,and Flavor-Changing-NeutralCurrent physics of Higgs boson and top quarks.We outline the requirements for detector performance and considerations for future development to achieve the anticipated scientific goals.The role of machine learning for innovative detector design and advanced reconstruction algorithms is also stressed.The CEPC flavor physics program not only develops new capabilities for exploring flavor physics beyond existing projects but also enriches the physics opportunities of this machine.It should be remarked that,given the richness of the CEPC flavor physics,this manuscript is not meant to be a comprehensive survey,but rather an investigation of representative cases.Uncovering the full potential of flavor physics at the CEPC will require further dedicated explorations in the future.展开更多
I.EXECUTIVE SUMMARY next-generation,high-intensity electron-positron collider"Higgs factory",such as the Circular Electron-Positron Collider(CEPC),is among the highest priorities for the global high-energy c...I.EXECUTIVE SUMMARY next-generation,high-intensity electron-positron collider"Higgs factory",such as the Circular Electron-Positron Collider(CEPC),is among the highest priorities for the global high-energy collider physics community.The CEPC can provide unprecedented opportunities for making fundamental discoveries and providing decisive insights in the quest for a"New Standard Model(SM)"of nature's fundamental interactions.The CEPC could:·Identify the origin of matter,especially the mechanism related to the first-order phase transition in the early Universe,which could produce a detectable gravitational wave signal.展开更多
文摘The Circular Electron Positron Collider(CEPC)proposed in China is a dual-ring collider with electron and positron beams in the energy range of 45.5–180 GeV.The main dipole in the CEPC collider is a dual-aperture dipole with a shared coil between the two apertures,forming an I-shaped structure that can reduce power consumption by 50%.Because of its long length and low field strength,the development of this dual-aperture magnet faces challenges regarding its mechanical design,field measurement accuracy,and field performance.Numerical simulations were performed to better understand the Earth's field and the effect of different BH curves on field performance.The field results of the prototype are presented herein,and the field quality satisfies the requirements.The remanent field accounts for 2%of the integral field at 140 Gs,and the hysteresis effect caused an increase in field strength of approximately 0.075%after a standardization cycle of the trim coils.Research on this prototype can provide useful insights for understanding low-field dipole magnets.
基金Project supported by Yifang Wang’s Science Studio of the Ten Thousand Talents Project。
文摘To reduce the energy demand and operation cost for circular electron positron collider(CEPC), the high efficiency klystrons are being developed at Institute of High Energy Physics, Chinese Academy of Sciences. A 800-k W continuous wave(CW) klystron operating at frequency of 650-MHz has been designed. The results of beam–wave interaction simulation with several different codes are presented. The efficiency is optimized to be 65% with a second harmonic cavity in three-dimensional(3D) particle-in-cell code CST. The effect of cavity frequency error and mismatch load on efficiency of klystron have been investigated. The design and cold test of reentrant cavities are described, which meet the requirements of RF section design. So far, the manufacturing and high-power test of the first klystron prototype have been completed.When the gun operated at DC voltage of 80 k V and current of 15.4 A, the klystron peak power reached 804 k W with output efficiency of about 65.3% at 40% duty cycle. The 1-d B bandwidth is ±0.8 MHZ. Due to the crack of ceramic window, the CW power achieved about 700 kW. The high-power test results are in good agreement with 3D simulation.
文摘Main quadrupole magnets are critical for the Circular Electron and Positron Collider(CEPC)and are specifically designed as dual aperture quadrupole(DAQ)magnets.However,the field crosstalk between the two apertures presents challenges.As the CEPC will work at four beam energies of Z,W,Higgs and ttbar mode,the DAQ magnets will operate at four field gradients spanning from 3.18 to 12.63 T/m.The first short quadrupole magnet prototype with the bore diameter of 76 mm and magnetic length of 1.0 m revealed the problems of large magnetic field harmonics and a magnetic center shift within the beam energy range.Accordingly,a compensation method was proposed in this work to solve the field crosstalk effect.By adjusting the gap height at the middle of the two apertures,the field harmonics and magnetic center shift are significantly reduced.After optimization,the short prototype was modified using a new scheme.The field simulations are validated from the magnetic measurement results.Further,the multipole field meets the requirements of the four beam energies.The detailed magnetic field optimization,field harmonics adjustment,and measurement results are presented herein.
基金This work was supported by the National Key Programme for S&T Research and Development(No.2016YFA0400400)the Youth Innovation Promotion Association CAS(2019016).
文摘Positron sources are one of the most important components of the injector of a circular electron positron collector(CEPC).The CEPC is designed as an e^(+)e^(−)collider for a Higgs factory.Its accelerator system is composed of 100-km-long storage rings and an injector.The design goal of the positron source is to obtain positron beams with a bunch charge of 3 nC.The flux concentrator(FC)is one of the cores of the positron source.This paper reports the design,development,and measurements of an FC prototype system.The prototype includes an FC and an all-solid-state high-current pulse modulator.Preliminary tests show that the peak current on the FC can reach 15.5 kA,and the peak magnetic field can reach 6.2 T.The test results are consistent with the theoretical simulation.The FC system fulfills the requirements of the CEPC positron source as well as provides a reference for the development of similar devices both domestically and abroad.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.12025502 and 12341504)。
文摘The circular electron-positron collider(CEPC)is designed to precisely measure the properties of the Higgs boson,study electroweak interactions at the Z-boson peak,and search for new physics beyond the Standard Model.As a component of the 4th conceptual CEPC detector,the drift chamber facilitates the measurement of charged particles.This study implemented a Geant4-based simulation and track reconstruction for the drift chamber.For the simulation,detector construction and response were implemented and added to the CEPC simulation chain.The development of track reconstruction involves track finding using the combinatorial Kalman filter method and track fitting using the tool of GenFit.Using the simulated data,the tracking performance was studied.The results showed that both the reconstruction resolution and tracking efficiency satisfied the requirements of the CEPC experiment.
文摘随着环形正负电子对撞机(Circular Electron Positron Collider,CEPC)方案的提出,由硅光电倍增管(Silicon Photomultiplier,SiPM)和塑料闪烁体组成的读出单元作为电磁量能器的预研方案之一,逐渐成为研究热点。在探测器预研阶段需要对读出单元性能进行充分研究,因此我们设计了一套自动化测试系统用于对读出单元进行测试、分析并改善其性能。利用DT5751波形采样插件、SiPM驱动电路板、步进电机、低压电源、继电器等完成硬件搭建,以LabVIEW为开发平台完成了软件的串行协议接口之间的通信,实现了读出单元的自动化测试,编写了相应的数据处理程序。在此基础上进行了SiPM刻度、闪烁体发光均匀性以及反射材料对光输出影响的研究。测试结果表明,ESR反射膜包裹的塑闪条具有最高的光输出,塑闪条耦合10μm像素SiPM的光输出为耦合25μm像素SiPM的三分之一。
文摘束流垃圾桶的材料、结构、尺寸的正确设计对于确保高能环形对撞机(Circular Electron Positron Collider,CEPC)直线加速器的安全运行有重要意义。采用蒙特卡罗程序FLUKA,研究了概念设计阶段的CEPC直线加速器束流垃圾桶的初步设计方案,给出了作为吸收体设计依据的射程的不同计算方法及验证过程,以及屏蔽体部分的材料选择与总体屏蔽厚度的关系;计算过程中引入减方差技巧提高了计算结果的精确程度。
基金Supported by the State Key Program of National Natural Science of China(2018YFA0404000,12135013)。
文摘The Circular Electron Positron Collider(CEPC)is designed to operate at key center-of-mass energies:91.2 GeV as a Z factory for precision Z boson studies,≈160 GeV at the threshold for W boson pair production,and 240 GeV as a Higgs factory for copious Higgs boson production.It can be upgraded to 360 GeV(CEPC-360 GeV)for enabling top quark-antiquark(tt)pair production.Beyond enabling high-precision measurements of the Standard Model(SM),CEPC-360 GeV is uniquely positioned to perform searches for new physics beyond the SM(BSM),serving as a valuable complement to hadron colliders.This paper presents a sensitivity study on the direct pair production of staus and smuons at the CEPC with√s=360 GeV,conducted via full Monte Carlo simulation.Under the assumptions of 1.0 ab^(−1)integrated luminosity and a flat 5%systematic uncertainty,CEPC-360 GeV could potentially discover the combined production of left-handed and right-handed staus up to a mass of 170 GeV(if they exist)or up to 169 for pure left-handed staus and 162 GeV for pure right-handed staus.For direct smuon production,the discovery potential reaches up to 178 GeV under the same conditions.
文摘We investigate the discovery prospects of a leptophilic gauge boson Z_(ℓ)at future e^(+)e^(-)colliders,focusing on a comparative study of the Circular Electron–Positron Collider(CEPC)and the International Linear Collider(ILC).Such a state naturally arises from an additional U(1)_(ℓ)'gauge symmetry,under which quarks remain neutral while all leptons carry a universal charge,motivated by neutrino oscillations and scenarios of physics beyond the Standard Model.As a clean benchmark,we study the process e^(+)e^(-)→μ^(+)μ^(-),including realistic effects of initial-state radiation and beamstrahlung.Our results indicate that the CEPC,with its very high luminosity at√s=240 GeV,can probe couplings down to g(ℓ)≈10^(-3)for Z_(ℓ)masses up to about 220 GeV.The ILC extends the sensitivity to heavier states in the multi-hundred GeV range through its higher√s stages.These findings demonstrate the strong complementarity of circular and linear colliders in exploring purely leptophilic interactions.
基金supported by the National Natural Science Foundation of China under Grant No.12275066by the startup research funds of Henan University+2 种基金supported by the Open Project of the Shanghai Key Laboratory of Particle Physics and Cosmology under Grant No.22DZ2229013-3supported by the National Key Program for S&T Research and Development under Contract No.2024YFA1610603supported by the National Natural Science Foundation of China under Grant No.W2441004.
文摘Several possible excesses around 95 GeV hint at an additional light scalar beyond the Standard Model.We examine the capability of the Circular Electron-Positron Collider(CEPC)to test this hypothesis in the Higgsstrahlung channel e^(+)e^(-)→ZS with Z→μ^(+)μ^(-)and S→τ^(+)τ^(-).A full detector simulation shows that the optimal center-of-mass energy for studying the 95 GeV light scalar is 210 GeV.A deep neural network classifier reduces the luminosity required for discovery by half.At L=20 ab^(-1),the 5σsensitivity of the CEPC to the signal strengthμ_(ττ)^(ZS)p reaches 0.016 and 0.020 for√s=210 GeV and 240 GeV,respectively.The corresponding thresholds for a 5%precision measurement areμ_(ττ)^(ZS)>0:10and>0:12.At√s=210 GeV(240 GeV),the 5σcoverage of all N2HDMFlipped samples with χ_(h_(95))^(2)<7:82requiresL=800 fb^(-1)(1.22ab^(-1)).These results establish a 210 GeV run,augmented by machine-learning selection,as the most efficient strategy to confirm or refute the 95 GeV excess at future lepton colliders.
基金Supported by Yifang Wang’s science studio of the ten thousand talents project。
文摘Purpose Radio frequency power supply system is an important part of Circular Positron Collider(CEPC).S-band klystron and C-band klystron supply power.More efficient S-band and C-band klystron prototypes are planned to move the project forward.Methods In TDR,the klystron optimizes electron beam bunch-clustering with BAC,gains favorable RF source params via simulations&comparisons.The remaining part is mainly through debugging to obtain the best operating parameters.Results Currently,RF power supply designs for collision ring,booster ring,linear accelerator injector and damping rings are feasible.IHEP's 650 MHz,800 kW klystron reaches an efficiency target of above 80%.Beam dynamics for 2860 MHz(80 MW)and 5720 MHz(80&50 MW)klystrons are finalized and in prototyping.Conclusions Efficient klystron development is crucial for CEPC's success,ensuring energy transmission,beam stability,and promoting eco-friendly design.Current design transitions smoothly to EDR,a key milestone.It meets domestic science equipment needs,boosting localization and innovation.
文摘1背景和动机2019年5月召开的格兰纳达(Granada)论坛是针对“The European Strategy for Particle Physics”(ESPP)所组织的研讨会,会上就国际高能物理界在希格斯粒子发现后如何推动高能物理基础研究达成了一些重要共识,特别是会议聚焦在将希格斯工厂作为未来对撞机的选项,并明确希格斯粒子性质的研究将是揭示隐藏在目前粒子物理标准模型后面更深层次基本规律的关键.
文摘Purpose The purpose of this paper is to examine the carbon footprint and the environmental impact of CEPC relative to its physics reach.Methods Both a general calculation model for construction impact and the detail status of Chinese electric grid for operation impact has been included to examine the carbon footprint of CEPC.The same electricity carbon intensity is used when the five proposed high energy colliders are compared.Results The carbon footprint to produce a Higgs boson for CEPC has a large range from 0.34 tons(clean energy)to 2.6 tons,depending on the type of energy source used.Conclusion Focusing on Higgs physics and considering the polarization effect only for Linear colliders,CEPC was found to have the lowest carbon emission per Higgs boson at 0.34 tons of CO2 using the same clean energy(20 ton CO2 e/GWh).
基金supported by Experimental Physics Center,Institute of High Energy Physics,Chinese Academy of Sciences[Y9291309U2].
文摘Purpose The circular electron-positron collider(CEPC)is a large international scientific facility with the goal of studying the Higgs particle.In order to achieve this goal,many sophisticated detectors need to be installed.As the basis for the installation of the internal sub-detector,the iron yoke needs to have sufficient strength and accuracy to ensure the accuracy of the internal sub-detector installation.Two different designs of CEPC detector barrel iron yoke structure are proposed.Simulation and structural optimization of these two designs are carried out,and valuable reference is provided for the subsequent design and optimization.Methods The selection of an appropriate design for the CEPC detector barrel iron yoke necessitates adherence to mechanical design requirements.In this paper,two mechanical design schemes of barrel iron yoke structure are presented,including structural design and analysis,mechanical properties analysis,dynamic properties analysis and structural optimization.Results Under the condition of 600 mm thickness,the symmetrical structure and the spiral structure are designed.The finite element analysis is used to simulate the mechanical analysis,modal analysis and seismic analysis of the two structures.Compared with the simulation results,the mechanical properties and dynamic properties of the spiral structure are better than those of the symmetrical structure under this condition.Conclusion Utilizing finite element analysis,the mechanical properties and dynamic properties of the two structures were determined.Following comparative analysis,it has been determined that the mechanical properties and dynamic properties exhibited by the spiral structure may be more in line with mechanical design requirements for the thin iron yoke structure.This study serves as a valuable reference for future design and optimization endeavors concerning the CEPC detector barrel iron yoke structure.
基金Supported in part by the National Key R&D Program of China(2022YFE0116900)the Basic Science Center Program(12188102)by National Natural Science Foundation of China。
文摘The Circular Electron Positron Collider(CEPC)is a large-scale particle accelerator designed to collide electrons and positrons at high energies.One of its primary goals is to achieve high-precision measurements of the properties of the Higgs boson and is facilitated by the large number of Higgs bosons that are produced with significantly low contamination.The measurements of Higgs boson branching fractions into bb/cc/gg andττ/WW*/ZZ*,where the W or Z bosons decay hadronically,are presented in the context of the CEPC experiment,assuming a scenario with 5600 fb^(-1)of collision data at a center-of-mass energy of 240 GeV.In this study the Higgs bosons are produced in association with a Z boson,with the Z boson decaying into a pair of muons(μ^(+)μ^(-)),which have high efficiency and resolution.To separate all decay channels simultaneously with high accuracy,the Particle Flow Network(PFN),a graph-based machine learning model,is considered.The precise classification provided by the PFN is employed in measuring the branching fractions using the migration matrix method,which accurately corrects for detector effects in each decay channel.The statistical uncertainty of the measured branching ratio is estimated to be 0.55%in the H→bb final state and approximately 1.5%-16%in the H→cc/gg/ττ/WW*/ZZ*final states.In addition,the main sources of systematic uncertainties in the measurement of the branching fractions are discussed.
基金Supported by the National Natural Science Foundation of China(Grant No.12175249).
文摘Purpose Future large high-luminosity electron–positron colliders such as circular electron positron collider(CEPC)and future circular collider(FCC-ee)require nanometer-sized beams at the interaction point(IP).The luminosity is very sensitive to the beam orbit drifts at the IP.It is essential to have a fast luminosity feedback system at the IP to maintain optimum beam collision conditions and prevent a luminosity degradation due to orbit drifts in the presence of mechanical vibrations and dynamical imperfections.Methods We considered two possible methods for this purpose for CEPC:one based on measurements of the luminosity and the other based on measurements of the beam orbits around the IP.Results In this paper,we present the preliminary design consideration for a fast luminosity feedback system at the IP of CEPC.
基金financial support from the National Natural Science Foundation of China(NSFC)(12125507,12047503,12035008,2211530479,12475094,12135006,12075097,12375086,2022YFA1601903,12061141007,12375091,12342502,12235018,12335003,12105100,12475106,11961141015,12188102,12175245,12205171,12321005,tsqn202312052,2024HWYQ-005,12405121,12447167,12061141006,12405102,12125503,12305115,12075213,12335005,12235008)the Chinese Academy of Sciences(YSBR-101,XDB34030000)+11 种基金the National Key R&D Program of China(2022YFE0116900,2023YFA1606703,2022YFA1601901)the National Key Research and Development Program of China(2023YFA1606300)the Excellent Postdoctoral Program of Jiangsu Province(2023ZB891)the Shenzhen Science and Technology Program(202206193000001,20220816094256002)the Natural Science Foundation for Distinguished Young Scholars of Henan Province(242300421046)the Beijing Municipal Natural Science Foundation(JQ22002)the Area of Excellence(AoE/P-404/18-3)the General Research Fund(16304321)(both grants are issued by the Research Grants Council of Hong Kong S.A.R)the MOST National Key R&D Program(2023YFA1606303)the Shanghai Key Laboratory for Particle Physics and CosmologyKey Laboratory for Particle Astrophysics and Cosmology(Ministry of Education)Shanghai Jiao Tong University。
文摘We discuss the landscape of flavor physics at the Circular Electron-Positron Collider(CEPC),based on the nominal luminosity outlined in its Technical Design Report.The CEPC is designed to operate in multiple modes to address a variety of tasks.At the Z pole,the expected production of 4 Tera Z bosons will provide unique and highly precise measurements of Z boson couplings,while the substantial number of boosted heavy-flavored quarks and leptons produced in clean Z decays will facilitate investigations into their flavor physics with unprecedented precision.We investigate the prospects of measuring various physics benchmarks and discuss their implications for particle theories and phenomenological models.Our studies indicate that,with its highlighted advantages and anticipated excellent detector performance,the CEPC can explore beauty andτphysics in ways that are superior to or complementary with the Belle II and Large-Hadron-Collider-beauty experiments,potentially enabling the detection of new physics at energy scales of 10 TeV and above.This potential also extends to the observation of yet-to-be-discovered rare and exotic processes,as well as testing fundamental principles such as lepton flavor universality,lepton and baryon number conservation,etc.,making the CEPC a vibrant platform for flavor physics research.The WW threshold scan,Higgs-factory operation and top-pair productions of the CEPC further enhance its merits in this regard,especially for measuring the Cabibbo-Kobayashi-Maskawa matrix elements,and Flavor-Changing-NeutralCurrent physics of Higgs boson and top quarks.We outline the requirements for detector performance and considerations for future development to achieve the anticipated scientific goals.The role of machine learning for innovative detector design and advanced reconstruction algorithms is also stressed.The CEPC flavor physics program not only develops new capabilities for exploring flavor physics beyond existing projects but also enriches the physics opportunities of this machine.It should be remarked that,given the richness of the CEPC flavor physics,this manuscript is not meant to be a comprehensive survey,but rather an investigation of representative cases.Uncovering the full potential of flavor physics at the CEPC will require further dedicated explorations in the future.
基金the Natural Science Foundation of China(NSFC)(11905162,12035008,12075097,12075123,12090060,12090064,12105248,12135006,12175039,12205227,12205312,12205387,12205171,12235008,12321005,12235001,12305094,12305115,12335005,12375091,12375094,12375096,11975129,12375194,12447167,12475094,12475101,12475106,12475111,12425506,12375101,12405119,12405101,12505121,12135007,12175218,12075213,12335005,12175243,12533001,12125503,12305103,12505120,12575099,12505122,12342502,12575106,12147214,W2432006,W2441004)the National Key R&D Program of China(2024YFA1610603)+22 种基金the China Postdoctoral Science Foundation(2023M732255,2025M773403,GZC20231613)the Natural Science Foundation of Jiangsu Province(BK20210201)the Natural Science Foundation of Henan(Distinguished Young Scholars of Henan Province)(242300421046)the Natural Science Foundation of Sichuan Province(2025ZNSFSC0880)the Guangdong Major Project of Basic and Applied Basic Research(2020B0301030008)the Department of Science and Technology of Shandong province(tsqn202312052,2024HWYQ-005)the Startup Research Fund of Henan Academy of Sciences(20251820001)the Excellent Young Talents Program of Wuhan University of Technology(40122102)the research program of the Wuhan University of Technology(3120625397,2020IB024)the Fundamental Research Funds for the Central Universities(JZ2023HGTB0222,WUT:2022IVA052)the Excellent Scholar Project of Southeast University(Class A)the Big Data Computing Center of Southeast University,National Science and Technology Council,the Ministry of Education(Higher Education Sprout Project NTU-114L104022-1)the Center for Theoretical Sciences of Taiwan,and Vietnam National Foundation for Science and Technology Development(NAFOSTED)(103.01-2023.50)the Research Office of the University of the Witwatersrand and South African Department of Science and Innovation through the SA-CERN programthe self-determined research funds of Central China Normal University from the colleges'basic research and operation of MOE(CCNU24AI003)SJTU Double First Class start-up fund(WF220442604)the Innovation Capability Support Program of Shaanxi(2021KJXX-47)the Slovenian Research Agency under the research core funding No.P1-0035,the research grants J1-3013,N1-0253,CONICET,ANPCyT under project(PICT-2021-00374)Higher Education Sprout Project(NTU-114L104022-1)KIAS Individual Grants(PG086002)at the Korea Institute for Advanced Study,FAPESP(2021/09547-9)the Slovenian Research Agency under the research core funding(P1-0035)research grants J1-3013,N1-0253the bilateral project Proteus PR-12696/Projet 50194VC。
文摘I.EXECUTIVE SUMMARY next-generation,high-intensity electron-positron collider"Higgs factory",such as the Circular Electron-Positron Collider(CEPC),is among the highest priorities for the global high-energy collider physics community.The CEPC can provide unprecedented opportunities for making fundamental discoveries and providing decisive insights in the quest for a"New Standard Model(SM)"of nature's fundamental interactions.The CEPC could:·Identify the origin of matter,especially the mechanism related to the first-order phase transition in the early Universe,which could produce a detectable gravitational wave signal.
