1. Progress of CEPC mechanics system
Haijing Wang
November 18-20, 2019, IHEP
The 2019 International Workshop on High Energy Circular Electron Positron Collider

2. Outline Overview Tunnel mockup Transport vehicles “Mini” CEPC model
Movable collimators
Mechanics at MDI region
Summary

3. Overview
CEPC is composed by the double ring Collider, the Booster, the Linac and Transport lines.
In TDR stage, the CEPC mechanics system mainly focuses on the optimization of the space for the installation, the mechanics at the MDI region and the movable collimator design.

4. Tunnel mockup
3D models of some typical devices in CDR.

5. Tunnel mockup
A tunnel mockup is designed for the interface checking of the equipment locations, installation, alignment and transportation. It includes part of arc section and part of RF section.
The arc section of Collider and Booster includes two dipole cores (or two dipoles), one quadrupole, one sextupole and one BPM.
The RF section of Collider and Booster includes one cryomodule each.
The total length is 40 meters.

6. Tunnel mockup

7. Tunnel mockup
The relative locations between magnets in each ring is the same as the lattice design.

8. Horizontal driven unit
Transport vehicles
Over 80% of the tunnel length is covered by magnets. Efficiency of transportation and installation must be considered.
Transport vehicles are designed for the magnets transportation and coarse positioning.
Accuracy of coarse positioning: better than 0.5 mm.
Vertical driven unit
Chassis
Balance weight
Horizontal driven unit
Load support
* Cooperate with Beijing North Vehicle Group Corporation.

9. Transport vehicles
Flexible load support for “long” devices and “short” devices
Transportation and coarse location of magnets in Booster
Transportation and coarse location of magnets in Collider
* Cooperate with Beijing North Vehicle Group Corporation.

10. “Mini CEPC” model
The “Mini CEPC” is a 100 meters long, anamorphic model of CEPC, which will be used for popularization of CEPC.
* Cooperate with Zhong Ke High Energy Science and Technology Ltd,. Co

11. “Mini CEPC” model
The “Mini CEPC” is a 100 meters long, anamorphic model of CEPC, which will be used for popularization of CEPC.
The Booster of “Mini CEPC” is under design.
The “Mini CEPC” is assumed at the same site as Tunnel mockup.
* Cooperate with Zhong Ke High Energy Science and Technology Ltd,. Co

12. Movable collimators
Located in straight section between two dipoles, the length is 800 mm.
Four horizontal collimators in each ring are designed in the TDR stage.
Synchrotron radiation is about 30MW. The load can be even higher if updated to 50MW.
We use Glidcop-Al15 for thermal analyses. The photon energy damping in material can not be neglected.
Photon energy damping in
300 KeV
Highest Von Mises Stress by synchrotron radiation: 81 MPa
Highest temperature by synchrotron radiation: 148 ℃

13. Movable collimators
We are also studying laminated materials with metal and membrane of high thermal conductivity for severe heat load, the photon absorber is also considered.
Y: Highest temperature;
X: Thickness of membrane of high thermal conductivity
Laminated material with copper and graphene film
Cooling method
Loads
Highest temperature（℃）
Copper & water
Surface load
286
Volume load (Damping of X ray)
148
Laminated material & water
146

14. Movable collimators
Two inner profiles are designed, gradual rectangle and gradual ellipse with movable stoppers in them.
RF fingers are at the edges of the stoppers to decrease impedance.
Gradual rectangle profile
Gradual ellipse profile
Energy loss (no RF fingers) (W)
Higgs W Z
Gradual rectangle profile
Stopper open 66
267
933
Stopper closed 39
160
560
Gradual ellipse profile 8 32
112 19 76
266
* From Y Liu et al., Impedance and Collective Instabilities for Collider, Booster and damping ring in CEPC, this workshop

15. Mechanics at MDI region
Installation scenario of MDI
Assume the IP chamber and the detectors, the yoke have been installed.
The remoted vacuum connection methods have been reviewed.
The support system of cryomodule is under studying.
The main body of Lumical has just been moved to the detector part, the details have not been updated.
Pre-alignment of SC magnets and installation of accelerator components
The connection and alignment of one side
The similiar procedure at the other side

16. Mechanics at MDI region
Remote vacuum connection methods:
Leak rate requirement: ≤2.7e-11Pa.m3/s
RVC similar to SuperKEKB as baseline, and studying other schemes at the same time.
* Cooperate with Shenyang Huiyu vacuum technics co., Ltd.

17. Mechanics at MDI region
Remote vacuum connection methods:
Leak rate requirement: ≤2e-10 Torr.L/s
RVC similar to SuperKEKB as baseline, and studying other schemes at the same time.
RVC Design
Inflatable seal design
Remote chain seal design
Experiment structure
* Cooperate with Shenyang Huiyu vacuum technics co., Ltd.

18. Mechanics at MDI region
Support system of SC magnets
The alignment accuracy of SC magnets: ≤30 μm
We are trying our best to find the solution.
Cryomodule
Adjusting mechanism
Support bed
Movement mechanism
Max deformation owing to gravity: 190 um
Max deformation owing to gravity varies 48 um by 1 ℃ environment temperature change
* Cooperate with Beijing Institute of Space Mechatronics

19. Summary
A 40 meters long tunnel mockup has been preliminary designed for the interface checking of the equipment locations, installation, alignment and transportation.
Transport vehicles are preliminary designed for the magnets transportation and coarse positioning.
“Mini CEPC” are under design for popularization of CEPC, which length in 100 meters.
The preliminary thermal and impedance analyses of movable collimators have been done, based on which the optimization of the inner profile is on-going.
For the MDI region, the design of the remote vacuum connection methods have been reviewed, and the support system of SC magnets is under design.

20. Thanks for your attention!