1. BEPCII Prealignment Installation Survey and Alignment Accelerator Center of IHEP Xiaolong Wang 2007.5.3

2. Brief introduction of BEPCII Alignment BEPCII alignment can be divided into three parts, calibration magnets, prealignment installation and tunnel survey and alignment. As BEPCII is constructed in the existing BEPC tunnel, the space for survey and installation is very narrow. So we arranged calibration magnets and prealignment installation in a hall outside of the tunnel. There are 84 cells need to do prealignment installation,and it was started on August 2005 and finished on August 2006.

3. BEPCII Prealignment Installation introduction We arranged two groups to do magnets calibration and prealignment installation together. Each group includes two alignment technicians and two workers. Beside these, a lift worker worked for these two groups. Measurement devices are laser tracker, leica NA2 and electronic gradienter. The components need to install in a cell generally are dipole, quadruple, sextuple, BV magnet, vacuum system, girder and so on. Each time can install two cells and finished in 4- 5 days.

4. BEPCII Prealignment Installation introduction According to the sequence of the prealignment, it includes calibration magnets, install magnets on the girder, roughly adjust the magnets, install vacuum system, precisely adjust the magnets and the vacuum chamber, fix the magnets and the vacuum system to the girder, lifting and transport the cell to the tunnel. We use laser tracker to do magnets calibration. Through measuring the fiducial planes and the fiducal points on the magnet, we can construct a frame for the magnet, in this frame we can get the coordinates of the fiducal points.

5. BEPCII Prealignment Installation introduction Prealignment cell Calibration dipole Calibration sextuple

6. BEPCII Prealignment Installation introduction Accelerator physics requires dipole’s Roll tolerance should be 0.1mrad, it’s can not be realized only with laser tracker. We use leica NA2 and electronic gradienter to do the Roll calibration. Leica NA2 Adjust the lower pole to level Target Measure dipole’s Roll Electronic gradienter Fiducial plane

7. BEPCII Prealignment Installation introduction After get the calibration coordinates of the magnets that are installed in one cell, we should calculate the nominal coordinates of these magnets. For each cell, we constructed a frame. The frame’s origin is on the center of the dipole, z points to the beam direction, y vertically points to the up, right hand coordinate system. According to the parameters given by accelerator physics we can convert these calibration coordinates to the nominal coordinates in the cell frame. After get the nominal coordinates, we input them into the laser tracker and then survey and adjust the magnets to the required installation precision.

8. BEPCII Prealignment Installation introduction We found temperature change can markedly influence the precision of the magnets’ position. It’s necessary to do some correction to the nominal coordinates. Through longtime experiment, we got an appropriate correctional coefficient, each time before adjustment, we use this coefficient multiply the nominal coordinates to do the correction.

9. BEPCII Prealignment Installation introduction Requirement of magnets calibration and prealignment installation precision. X (mm) Y (mm) Z (mm) dipole0.1 0.15 quadruple0.04 0.1 sextuple0.05 0.1 BV magnet 0.15 X (mm)Y (mm)Z (mm) quadruple0.05- 0.08 0.08 sextuple0.05- 0.08 0.08 BV magnet 0.15 vacuum chamber 0.50.30.5 magnets calibration precision prealignment installation precision

10. BEPCII storage rings alignment introduction Storage Ring 240 meters long Beijing Synchrotron Radiation Facility Beijing Spectrometer Two transport lines, total 160 meters long LINAC, 202 meters long Beijing Synchrotron Radiation Facility

11. BEPCII storage rings alignment introduction The BEPCII Surface Network consists of 4 permanent monuments named T65P, T65E, L101 and L102. We use T65P and T65E to control the storage ring position, use the L101 and L102 to control the LINAC position. LINAC Storage Ring Two permanent points to control LINAC 230 meters Y X Two permanent points to control ring Y X Transport Line

12. BEPCII storage rings alignment introduction LINAC alignment was finished in 2005, here only introduce the storage rings’ installation and alignment. We layout a three dimensional control network in storage rings tunnel, measure its horizontal coordinate with total station and laser tracker, measure its vertical coordinate with level, and then we measure and adjust the components’ position with laser tracker relative to the three dimension network.

13. The Alignment Tolerance(rms) The global point error of horizontal network is 0.82mm The relative point error of horizontal network between two adjacent control point is 0.08mm. The global point error of vertical network is 0.33mm The relative point error of vertical network between two adjacent control point is 0.06mm. The global position accuracy of equipment in horizontal is 0.82mm and vertical is 0.33mm. The relative position accuracy of equipments in horizontal and vertical is 0.15mm

14. BEPCII storage rings alignment introduction The surface network in horizontal consist of 37 main control points. In collision area (from R25 to R30) and aisle area (R37,R1,R17,R18 ), we have to measure between long distance and the interference to measurement is great, so we use total station TDA5005 to measure the surface network. It needs about 5 days. The surface network of the BEPCII storage rings

15. BEPCII storage rings alignment introduction The total station was centered on the point to measure the directions and distances of other points like the figure. The triangulation measurement accuracy of the total station is 2.2 seconds. The distance measurement accuracy of the total station is 0.17mm. Surveyor Total Station We use the total station of Leica TDM5005 to survey the surface network in horizontal in forced centering mode on the ground.

16. BEPCII storage rings alignment introduction The floor and wall of storage rings tunnel was populated with 3 dimensional monuments In the arc area, we have good measurement environment, so use laser tracker to measure the surface network can be efficiently. monuments on floor along the girder. intervals are about 3.5m monuments on floor along the foot of the wall. monuments on the wall.about 1.8m high Laser tracker. The Cut View of Tunnel

17. BEPCII storage rings alignment introduction Each station, laser tracker measures two front sections and three back sections. In one station 20 monuments can be measured. It needs about 10- 12 days to finish the network survey by laser tracker. Laser tracker surveys tunnel network Laser tracker station monuments

18. BEPCII storage rings alignment introduction We use the Leica NA2 level to measure the vertical coordinate of the tunnel network. The level is setup along tunnel at intervals of 7 meters to measure the height of every monument in direct and reversed observation mode. Optical tooling scale for measuring height of wall monument The leveling staff for measuring the height of floor monument

19. BEPCII storage rings alignment introduction The closing error of height in direct and reversed observation should be less than 0.1mm. Using “shanwei” software to do the vertical coordinate adjustment. The maximum absolute vertical coordinate error should be 0.33mm(rms). The maximum relative vertical coordinate error between adjacent control points should be 0.06mm.

20. BEPCII storage rings alignment introduction The construction of 3 dimensional nominal coordinate of the tunnel network. The three dimensional coordinate of the network consists of horizontal coordinate and vertical coordinate. The horizontal coordinate stems from a measurement to the network in horizontal with total station and tracker. The vertical coordinate stems from a measurement to the network in vertical with level.

21. BEPCII storage rings alignment introduction For the installation and alignment of the storage ring, we use laser tracker to align the components with respect to the 3D tunnel control network, and also improve the alignment accuracy with level and electronic gradienter. Before adjust a cell, we first check the position correlation of the magnets on the girder. If their correlation occurs to change and don’t satisfied with the requirement, we will readjust them.

22. BEPCII storage rings alignment introduction When adjusting the position of a component, we first use the laser tracker to measure monuments populated in 3 dimensions adjacent to the component, and best-fit the actual coordinates of these monuments to their nominal coordinates of the network, the standard deviation of the best-fit should be less than 0.07mm. After the best-fit of coordinates, the difference between nominal position and actual position of the component can be displayed by laser tracker. Adjust the component until the offsets within required installation precision. We measured the tunnel network and components again after all components of BEPCII storage rings had been wholly installed, then smoothed all the components.

23. BEPCII storage rings alignment introduction Storage rings alignment schedule. Jul. 2005 - Aug. 2005 Survey the tunnel network. Sep.2005 – Oct.2005 Mark beam lines on the tunnel floor. Mar.2006 – Sep.2006 Storage rings tunnel installation and alignment. Oct.2006 – Nov.2006 The adjustment to smooth all the components.

24. BEPCII storage rings alignment introduction Tolerable displacements for storage ring magnets (components) defined by the accelerator physics The circumference of storage rings cannot deviate from its design value by more than 5mm; the difference between two rings has to be set within 4mm.

25. Summary According to the component installation tolerance of the BEPCII storage rings which accelerator physics gives, the scheme of every taches had been carefully studied and the total tolerance was reasonably distributed to the taches in course of the component installation. So the total tolerance of the component installation is successfully limited in the range of physics requirement. Thanks for your attentions !