CEPC Technical Design Report

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.

Mechanical design and analysis of capture superconducting solenoid for EMuS

Purpose A capture superconducting solenoid is designed for the Experimental Muon Source(EMuS)which is proposed at China Spallation Neutron Source(CSNS)in Dongguan for muon science and neutrino physics research.The capture superconducting solenoid of the EMuS consists of four coils with different radius generating a peak central field of 5 T at 3944 A of nominal current.Methods The aluminum-stabilized NbTi Rutherford cable is used to wind the solenoid coils.Iron yokes are arranged for flux returning and field shielding.Ti alloy Ti-6Al-4V rods are adopted to support the cold mass.The vacuum vessel of the solenoid is manufactured by 304 stainless steel.The coils are pre-stressed by interference fits assembly,the outer support cylinder or binding the coils with aluminum alloy wire in order to reduce the peak stress of the coils.The parameters of the coils such as the thickness and the tensile stress of the binding wire and the thickness of the outer support cylinder have been optimized in order to minimize the cold mass by using FEA software.Results The maximum stress in the winding is allowable with two layers of 40 mm thickness outer support cylinder through interference fits assembly.But the maximum stress in the winding is allowable with 40 mm thickness of binding wire and 30 mm thickness of outer support cylinder.Conclusion The method of binding the windings with aluminum alloy wire is suggested to be used to manufacture the solenoid.This paper presents the mechanical design and analysis of the capture superconducting solenoid for EMuS.

Analysis of thermal characteristics for EMuS capture solenoids

Purpose The Experimental Muon Source(EMuS)project proposed at the China Spallation Neutron Source(CSNS)is a facility for muon applications and neutrino physics research.The EMuS target station adopts a superconducting solenoid scheme to meet the requirements of muon and pion capture.The capture solenoid consists of four solenoids with different apertures to meet the requirements of the central magnetic field up to 5T.Due to the high-irradiation environment,the capture solenoid adopts aluminum-stabilized Rutherford cable winding scheme to reduce the heat deposition on the coil.The magnet design considers the degradation of properties of aluminum stabilizer after continuous neutral irradiation.Due to the characteristics of the coil material,the magnet has different steady-state thermal characteristics and quench performance during different operating periods.Method and result Through the analysis of the operating characteristics,this paper proposes the design of the magnet structure and quench protection scheme.According to the simulation,the current design can satisfy a continous operating time of 200 days per year.