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INSTITUTE OF HIGH ENERGY PHYSICS CEPC Survey and Alignment Xiaolong Wang, Lan Dong Na Ma, Zhu Hongyan Oct. 9-12, 2018, IWAA2018 Fermilab Outline 1 Introduction 2 CEPC Control Network Design 3 Component fiducialization and alignment 4 Alignment precision requirement 5 Workload estimate 6 Researches 7 Summary 1 Introduction Circular Electron Positron Collider (CEPC) is a huge particle collider aim to measure the precise properties of the Higgs boson which was discovered at CERN by LHC. First proposed in 2012, after several times

argumentation and modification its conceptual design report is finished in June 2018. CEPC is designed to run at beam energy 120GeV for seven years to generate over a million Higgs bosons then it will be operated at 45.5GeV for two years to generate ten billion Z bosons as well as run at 80GeV for a year to produce around 15 million pairs of W+ and W-. The ideal construction schedule is from 2022 to 2030. Following a decade of studying the Higgs, Z and W bosons, it is hoped to begin construction a protonproton collider inside the existing tunnel in 2040. RF regions 3.24km CEPC General Layout Interaction regions 3.32km LSS4 IP4

1.20km IP1 1.6km BT L LSS3 1.20km 1.20km LINAC LSS 1 straight section regions IP3 IP23.24km 3.32km

Arc region 10.2km 1.20km ring=99.67km Ring tunnel has a double-ring and a booster. Booster is hung on the top of tunnel about 3.2m above floor. Booster Double-ring Ring tunnel model Double aperture magnets Interaction region In interaction region Main ring

there are two tunnels Detector one is for booster the other is for main booster ring. Site selection Drill & Blast Changchun, Jilin Qinhuangdao, Hebei Huangling, Shaanxi Huzhou Zhejiang Shenshan, Guangdong Where to build CEPC is decided by what kind of support from the local government we will receive in terms of ,for example, laboratories, living conditions, roads and power supply. S&A Overview Survey and Alignment group(S&A) is responsible for CEPC components position alignment and maintenance. work will be carried out in two phases. The first phase is carried out in CEPC construction

period. Align all of the components to the designed geometric positions within a certain precision provide an initial orbit for CEPC commissioning. The second phase is in CEPC stop periods, the beam will be a benchmark and according to the beam requirement to do orbit smooth alignment. Ultra-long CEPC circumference brings two challenges to S&A Improve working efficiency: put in more work teams and instruments, R&D advanced technologies. Accidental error accumulation of ultra-long narrow tunnel control network and its accuracy control. S&A work can be divided into 4 parts: Alignment control networks survey Components fiducialization and pre-alignment Tunnel installation alignment Components segmentally smooth alignment 2 CEPC Control Network Design Control networks provide an unified location

reference frame for the whole accelerator and control the error accumulation of survey and alignment. For the ultra-long CEPC we designed a 3 levels control network. Surface control network Backbone control network Tunnel control network Surface control network provides the absolute position control for CEPC and high precision constraint datum for tunnel control network. Composed of 16 permanent points (4 external points and 12 internal points) 2 points locate Linac, 2 points locate LTB, 8 points locate ring. These 12 internal points will be built in CEPC tunnel, they are a part of the tunnel control

network. Tunnel permanent point Y Z X The pillars of tunnel permanent points are built on the base rock Shield from soil with steel tube. Monument can hold 1.5 half ball target/ reflector External control point can be measured by GPS There are many shafts link the tunnel and ground surface, we can use these shafts to measure the tunnel permanent points from ground

Shafts Use GPS and level measure the surface network Permanent point in tunnel can be plumbed to a cast point on the ground through the shaft. The measurement accuracy of surface network is about 10mm in horizontal direction and about 7mm in vertical direction. Component absolute accuracy depends on the distance between two adjacent permanent points. CSNS 210m Linac transversal maximum deviation is 0.15mm. CERN simulation result shows 8mm for 5km and 12mm for 10km. GPS receiver cast point Permanent poin

Instruments survey LEICA GS10 AR20 and software for Surface network + LGO software LEICA Wild NL LEICA AT401 LEICA NA2 + SHANWEI software Tap e The height between GPS and tunnel permanent point can vary from tens of meters to two hundred meters depends on where

CEPC will be built. According to our experience of CNSN, where the biggest height is 30 meters, using Wild NL, the plumb accuracy is 0.5mm. The height can be measured by AT401. If the height is too big, we plan to use a transit square to plumb point and use a total station to measure the height. Total station Backbone control network Strengthen the tunnel control network reduce error accumulation. tunnel control point It is a kind of large span doubletraverse structure control network. Points of adjacent sections must be intervisible and the distance should be

as long as possible Use total stations to carry out backbone network survey. Backbone control network Future upgrade to aa Proton accelerator Tunnel control network is position reference of components installation and alignment. tunnel control network along CEPC tunnel will be evenly distributed with an interval of 6 meters, each section there

are 4 control points, two on the floor, one on the outer wall and one on inner wall. Use laser trackers and levels carry out tunnel network survey Booster Tunnel cross-section view Double-ring BEPCII BEPCII 237.53m ring the point measure error is better than 0.08mm. (2006,2008,2010,2012) Control points much denser than CEPC The point measure accuracy of CEPC is about

0.12mm 3 Component fiducialization and alignment Component fiducialization is to draw the beam center to its fiducial points, then the fiducial points coordinates can be transferred to CEPC global coordinate system and used for component tunnel alignment Laser tracker The precision of components fiducialization is about 0.05-0.10 Articulated arm mm. Photogrammetry Get boundary dimensions Reference features Dipole Magnet Fiducialization Datum Planes Camera Bunching cavity Fiducialization with Articulated flexible arm Photogrammetry

measurement Optical instruments Level, Transit square, electronic gradienter are also necessary. Rotating coil To improve magnet fiducialization accuracy, we will use magnetic center measurement substitute mechanical center measurement.

We use the tunnel control network and laser trackers to perform tunnel components alignment. Measure the tunnel control network and through best-fit to determine the laser tracker position in CEPC global coordinate system. Using laser tracker measure the component fiducial points to obtain the component position. Adjust the component to the required tolerance. After the initial installation, we will carry out an overall survey, best-fit the result with the nominal coordinates to find the large deviations then do smooth adjustment. Components tunnel alignment accuracy CEPC should be built on a plane, its normal direction is Z. The earth is an ellipsoid, its gravity directions along the CEPC

tunnel are not parallel with the Z. Z R=6374km CEPC ring center The angle between Z and tunnel local gravity direction is about 4.6 In tunnel components will be not perpendicular to the ground. The earth tunnel D=32km

CEPC plane z 4.6 Gravity direction Interaction region alignemnt Alignment in the interaction region will be much more demanding than in the Arcs due to the extremely low functions. At present we have not detailed structure design of interaction region. The detector hall is 40mX30m, the detector is about 14mX15m. The basic strategy is using laser trackers to do a rough

alignment first, then use a laser collimator system to carry out the refined alignment, which can reach high precision and suitable for straight section alignment. We will install a laser collimator system beside the detector . Using laser trackers and control network align the laser parallel with the nominal beam orbit. Then we can use the laser as a reference align all the components to the beam orbit. The accuracy we want to achieve is better than 0.1mm. Laser collimator system Laser tracker Monitoring system Settlement Hydrostatic Levelling System(HLS) monitor HLS sensors will be installed on the ground near the

components. Every 300-500m will be equipped with a sensor along the tunnel Accuracy 0.01mm HLS Sensor Component transversal and vertical monitor Wire Positioning System (WPS) HLS Calibration facilities Temperature & Humidity laboratory 60m calibration bench Laser interferometer Coordinate Measuring Machine Tool microscope

4 Alignment precision Provide by physics group requirement Component Dipole Quadrupole Sextupole Corrector Transversal Vertical Longitudinal Pitch Yaw Roll /mm /mm /mm /mrad /mrad /mrad 0.1 0.1 0.15 0.2 0.2 0.1 0.1 0.1

0.15 0.2 0.2 0.1 0.1 0.1 0.15 0.2 0.2 0.1 0.1 0.1 0.15 0.2 0.2 0.1 Alignment precision statistic Component

Fiducialization /mm Control network /mm Measurement /mm Adjustment /mm Totall /mm 0.05~0.1 0.12 0.05 0.05~0.1 0.15~0.2

To meet the requirement, it needs to do some improvements Fiducialization, use Coordinate Measuring Machine, magnetic field measuring equipment 0.015~0.03mm After the initial installation alignment, we need to spend more time to do smooth alignment. Develop new alignment technique. 5 Workload estimate Component quantity preliminary statistics (incomplete) Component Dipole Quadrupole Sextupole Corrector Superconducting Cavity Superconducting Cavity Assembly Superconducting quadrupole Superconducting sextupole Collider Ring

Booster 2546 3524 1864 5808 240 16320 2036 448 1206 96 40 8 32 12 Septum Magnet 4 Cavity

Detector Total 184 533 24 149 37 285 6 240 Accelerating structure BPM Total 144 22 Kicker Solenoid

Linac& BT 4900 2 21484 20284 1458 19050 6093 2336 7163 456 72 8 32 144 22 41 285 6 5140

2 40710 If dipoles longer than 10 meters are divided by 6 meters Component Dipole 93.4m Dipole 67m Dipole 61m Dipole 50m Dipole 45m Dipole 44.2m Dipole 34.1m Dipole 31.8m Dipole 28m Dipole 9.7m Collider Ring Piece

Total 4 16 64 20 4 2 16 12 11 9 8 240 44 18 128 20

8 160 16 6 96 32 6 192 2400 32 5 2 12000 64

2546 83 TheTotal number of components need to be aligned will be 13006 51170 1 group 1 day can alignment 2 difficulty components / 4 common components. If 1 group 1 day alignment 3 components, it will take 1 group 17057 days to finish 51170 components alignment The total length of tunnel control network is about 101610m. 1 group 1 day can measure 4 stations+4 stations repeat measurement, the length of 4 stations is about 24m.

It will take 1 group 4234 days to finish tunnel control network survey. How many time spend for alignment depends on how many groups we can have. 6 Researche s Develop automatic observation system to improve tunnel survey efficiency Integrates an automatic mobile platform and an photogrammetry instrument. The automatic mobile platform can be guided by a reflective stripe on the tunnel ground and provides a suitable position for vision instrument measurement. Automatic observation system

Trac e Cooperated with a company, we have developed a 3+3mm camera. Designed a five faces target for photogrammetry which can be observed from different directions. One million capacity coded object has been developed and the recognition software has been tested. We have carried out 3 times measurement experiment to explore the accelerator photogrammetry survey method. Result shows, photogrammety is more efficient and convenient than laser tracker, but the precision still need to be improved. 3m+3ppmm+3ppm Camera Five-face target

Photogrammetry experiment Geoid refining: Level measurement is based on the local geoid which gravity direction is not same with the CEPC global coordinate system Z axis. When we transfer the level measurement data to the global coordinate system the difference need to be considered. The geoid is an irregular surface because of earth density variance and the grounds undulation. We need to get a precise geoid model for CEPC

alignment. Using gravity, GPS and level instruments measure a certain density points within CEPC area. Use gravitational field data to establish the gridbased geiod model . Further researches need to be carried out and invite experts help us to make detailed schemes. CEPC plane 7 Summar y Alignment strategy is introduced. Surface network will be measured by GPS. How to plumb accurately for

long distance need further research. Component fiducialization is mainly carried out by laser tracker, articulate arm and photogrammetry. Detailed component fiducialization scheme will be made in future. Tunnel alignment is based on control network and laser tracker. A laser collimator system will be applied to decrease the alignment errors in interaction region. HLS and WPS will be used for stability monitoring. A preliminary workload estimate is made. The biggest challenges are how to increase tunnel survey efficiency and smooth alignment accuracy. To improve tunnel survey efficiency an automatic observation system base on photogrammetry is put forward. Geoid refining is essential, the detailed schemes need to be researched. Thanks

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