Correction to:Radiation Detection Technology and Methods(2024)8:1-1105.https://doi.org/10.1007/s41605-024-00463-y.In this article all authors name was missing in the springer link.It has been corrected.The original ar...Correction to:Radiation Detection Technology and Methods(2024)8:1-1105.https://doi.org/10.1007/s41605-024-00463-y.In this article all authors name was missing in the springer link.It has been corrected.The original article has been corrected.展开更多
Background Circular electron positron collider(CEPC)is a 100-km electron positron collider proposed by IHEP.The longitudinal coupled-bunch instability(LCBI)of CEPC main ring operating to study the Z particle(Z machine...Background Circular electron positron collider(CEPC)is a 100-km electron positron collider proposed by IHEP.The longitudinal coupled-bunch instability(LCBI)of CEPC main ring operating to study the Z particle(Z machine)may be a limiting factor of CEPC and needs to be considered seriously.Purpose The purposes of this paper are to calculate the LCBI caused by the fundamental mode of superconducting RF cavities in CEPC main ring,which is the most critical impedance,and to complete the design of the RF feedback systems suitable for CEPC,whose specifications can suppress the LCBI to a manageable level.Methods The LCBI growth rate in the CEPC main ring is calculated in the frequency domain.Two kinds of RF feedback,i.e.,direct feedback and one-turn delay feedback,are simulated with the program to suppress the LCBI.And according to the suppression effect of LCBI growth rate after adding RF feedback,the required design parameters are given.Results Two operation conditions of Z machine have severe LCBI without suppression,and dozens of longitudinal modes are unstable.Only the direct RF feedback is needed to suppress LCBI in the case of Z-30 MW,while both the direct RF feedback with maximum gain and one-turn feedback are needed in the case of Z-50 MW.The LCBI growth rates can be reduced to the order of half frequency of the synchronous oscillation.Conclusion The LCBI of CEPC Z machine has been studied.Selecting appropriate feedback RF feedback can reduce the LCBI to an acceptable value that bunch by bunch feedback can suppress.展开更多
Background CEPC is a 100-kilometer-long electron-position collider,aiming to produce Higgs,W and Z-pole.Double ring(DR)is the baseline design of its main ring,and advanced partial double ring(APDR)is the alternative o...Background CEPC is a 100-kilometer-long electron-position collider,aiming to produce Higgs,W and Z-pole.Double ring(DR)is the baseline design of its main ring,and advanced partial double ring(APDR)is the alternative one.Purpose The purpose of this paper is to study the beam loading effects and the corresponding longitudinal beam dynamics of CEPC DR and APDR.Methods The phase shift of the bunches modulated by the bunch gap is calculated with the approximation formulas and simulated with the program.All these methods are compared,and the application conditions of them are also elaborated.In addition,the longitudinal coupled-bunch instability in CEPC main ring is calculated by analytical formulas.Results In CEPC DR high-lumi Z,the phase shift can be reduced to 0.51 deg(°).Besides,the total number of unstable longitudinal modes is 15 in CEPC DR high-lumi Z when no feedback system is added.Conclusion The phase shift of the bunches in CEPC can be reduced to an acceptable value if the optimal filling pattern is chosen.For CEPC APDR,the RF parameters are calculated and the beam loading effects are tolerable.展开更多
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
Introduction The circular electron-positron collider(CEPC)will use a 650-MHz RF system with 240 two-cell cavities for the collider.The collider is a double ring with shared cavities for Higgs operation and separate ca...Introduction The circular electron-positron collider(CEPC)will use a 650-MHz RF system with 240 two-cell cavities for the collider.The collider is a double ring with shared cavities for Higgs operation and separate cavities for W and Z operations.The higher-order modes(HOM)excited by the intense beam bunches must be damped to avoid additional cryogenic loss and multi-bunch instabilities.Materials and methods To get the real damping results,two prototypes of HOM coupler have been fabricated and installed on the 650-MHz two-cell cavity.The HOMs have been verified by bead pulling method.A test bench with two 2-cell cavities is used to measure the real damping results and study HOM propagating properties for a cavity string.Conclusion In this paper,the impedance budget,HOM damping and HOM power requirements for the CEPC collider ring are given.The damping results measured for the fundamental mode and HOMs seem good compared with the simulated results.The absorbing efficiency of the absorber and the extraction power efficiency of HOM couplers were also achieved.展开更多
Background The power loss of cavity high-order modes(HOMs)is a key issue in Circular Electron and Positron Collider(CEPC)RF system design.A large HOM power may cause a quench of SC cavity.Purpose The purpose of this a...Background The power loss of cavity high-order modes(HOMs)is a key issue in Circular Electron and Positron Collider(CEPC)RF system design.A large HOM power may cause a quench of SC cavity.Purpose The purpose of this article is to study the beam-induced HOM power for CEPC collider ring.The factors influencing the cavity HOM power are also investigated.Methods Starting with the beam filling patterns,the beam spectrums of different beam time structures are deduced.Then,the longitudinal impedance is simulated for CEPC 2-cell 650 MHz cavity.Finally,the cavity HOM power is calculated for CEPC CDR design.Results The cavity HOM power is 459 W for Higgs,506 W for W and 1026 W for Z-pole.These values are smaller than the average values.There is no overlap between beam spectral lines and cavity HOM frequency.Conclusion The filling patterns of CEPC CDR Higgs,W and Z are safe.The dangerous filling patterns can be identified for CEPC Z-pole by scanning different parameters.展开更多
文摘Correction to:Radiation Detection Technology and Methods(2024)8:1-1105.https://doi.org/10.1007/s41605-024-00463-y.In this article all authors name was missing in the springer link.It has been corrected.The original article has been corrected.
文摘Background Circular electron positron collider(CEPC)is a 100-km electron positron collider proposed by IHEP.The longitudinal coupled-bunch instability(LCBI)of CEPC main ring operating to study the Z particle(Z machine)may be a limiting factor of CEPC and needs to be considered seriously.Purpose The purposes of this paper are to calculate the LCBI caused by the fundamental mode of superconducting RF cavities in CEPC main ring,which is the most critical impedance,and to complete the design of the RF feedback systems suitable for CEPC,whose specifications can suppress the LCBI to a manageable level.Methods The LCBI growth rate in the CEPC main ring is calculated in the frequency domain.Two kinds of RF feedback,i.e.,direct feedback and one-turn delay feedback,are simulated with the program to suppress the LCBI.And according to the suppression effect of LCBI growth rate after adding RF feedback,the required design parameters are given.Results Two operation conditions of Z machine have severe LCBI without suppression,and dozens of longitudinal modes are unstable.Only the direct RF feedback is needed to suppress LCBI in the case of Z-30 MW,while both the direct RF feedback with maximum gain and one-turn feedback are needed in the case of Z-50 MW.The LCBI growth rates can be reduced to the order of half frequency of the synchronous oscillation.Conclusion The LCBI of CEPC Z machine has been studied.Selecting appropriate feedback RF feedback can reduce the LCBI to an acceptable value that bunch by bunch feedback can suppress.
基金This study was supported by National Key Programme for S&T Research and Development(Grant No.:2016YFA0400400)National Natural Science Foundation of China(No.11575218)Key research Program of Frontier Science,CAS(Grant No.:QYZDJ-SSW-SLH004).
文摘Background CEPC is a 100-kilometer-long electron-position collider,aiming to produce Higgs,W and Z-pole.Double ring(DR)is the baseline design of its main ring,and advanced partial double ring(APDR)is the alternative one.Purpose The purpose of this paper is to study the beam loading effects and the corresponding longitudinal beam dynamics of CEPC DR and APDR.Methods The phase shift of the bunches modulated by the bunch gap is calculated with the approximation formulas and simulated with the program.All these methods are compared,and the application conditions of them are also elaborated.In addition,the longitudinal coupled-bunch instability in CEPC main ring is calculated by analytical formulas.Results In CEPC DR high-lumi Z,the phase shift can be reduced to 0.51 deg(°).Besides,the total number of unstable longitudinal modes is 15 in CEPC DR high-lumi Z when no feedback system is added.Conclusion The phase shift of the bunches in CEPC can be reduced to an acceptable value if the optimal filling pattern is chosen.For CEPC APDR,the RF parameters are calculated and the beam loading effects are tolerable.
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supported by National Key Programme for S&T Research and Development(Grant No.:2016YFA0400400)National Natural Science Foundation of China(No.:11905232)Xie Jialin Funding from IHEP
文摘Introduction The circular electron-positron collider(CEPC)will use a 650-MHz RF system with 240 two-cell cavities for the collider.The collider is a double ring with shared cavities for Higgs operation and separate cavities for W and Z operations.The higher-order modes(HOM)excited by the intense beam bunches must be damped to avoid additional cryogenic loss and multi-bunch instabilities.Materials and methods To get the real damping results,two prototypes of HOM coupler have been fabricated and installed on the 650-MHz two-cell cavity.The HOMs have been verified by bead pulling method.A test bench with two 2-cell cavities is used to measure the real damping results and study HOM propagating properties for a cavity string.Conclusion In this paper,the impedance budget,HOM damping and HOM power requirements for the CEPC collider ring are given.The damping results measured for the fundamental mode and HOMs seem good compared with the simulated results.The absorbing efficiency of the absorber and the extraction power efficiency of HOM couplers were also achieved.
基金National Key Programme for S&T Research and Development(Grant No.2016YFA0400400)National Natural Science Foundation of China(No.11575218)Key research Program of Frontier Science,CAS(Grant No.QYZDJ-SSW-SLH004).
文摘Background The power loss of cavity high-order modes(HOMs)is a key issue in Circular Electron and Positron Collider(CEPC)RF system design.A large HOM power may cause a quench of SC cavity.Purpose The purpose of this article is to study the beam-induced HOM power for CEPC collider ring.The factors influencing the cavity HOM power are also investigated.Methods Starting with the beam filling patterns,the beam spectrums of different beam time structures are deduced.Then,the longitudinal impedance is simulated for CEPC 2-cell 650 MHz cavity.Finally,the cavity HOM power is calculated for CEPC CDR design.Results The cavity HOM power is 459 W for Higgs,506 W for W and 1026 W for Z-pole.These values are smaller than the average values.There is no overlap between beam spectral lines and cavity HOM frequency.Conclusion The filling patterns of CEPC CDR Higgs,W and Z are safe.The dangerous filling patterns can be identified for CEPC Z-pole by scanning different parameters.
