BEPCII Prealignment Installation Survey and Alignment

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BEPCII Prealignment Installation Survey and
Alignment

• Accelerator Center of IHEP
• Xiaolong Wang
• 2007.5.3

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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.

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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.

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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.

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

• Accelerator physics requires dipoles Roll
  tolerance should be 0.1mrad, its can not be
  realized only with laser tracker. We use leica
  NA2 and electronic gradienter to do the Roll
  calibration.

Electronic gradienter
Target
Leica NA2
Fiducial plane
Adjust the lower pole to level
Measure dipoles Roll
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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 frames 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.

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BEPCII Prealignment Installation introduction

• We found temperature change can markedly
  influence the precision of the magnets position.
  Its 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.

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BEPCII Prealignment Installation introduction

• Requirement of magnets calibration and
  prealignment installation precision.

X (mm) Y (mm) Z (mm)
quadruple 0.05-0.08 0.05-0.08 0.08
sextuple 0.05-0.08 0.05-0.08 0.08
BV magnet 0.15 0.15 0.15
vacuum chamber 0.5 0.3 0.5
X (mm) Y (mm) Z (mm)
dipole 0.1 0.1 0.15
quadruple 0.04 0.04 0.1
sextuple 0.05 0.05 0.1
BV magnet 0.15 0.15 0.15
magnets calibration precision
prealignment installation precision
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BEPCII storage rings alignment introduction
Storage Ring 240 meters long
LINAC, 202 meters long
Beijing Synchrotron Radiation Facility
Two transport lines, total 160 meters long
Beijing Spectrometer
Beijing Synchrotron Radiation Facility
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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
Transport Line
230 meters
Two permanent points to control ring
Y
Two permanent points to control LINAC
X
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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.

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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

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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
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BEPCII storage rings alignment introduction
We use the total station of Leica TDM5005 to
survey the surface network in horizontal in
forced centering mode on the ground.

• 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.

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BEPCII storage rings alignment introduction

• In the arc area, we have good measurement
  environment, so use laser tracker to measure the
  surface network can be efficiently.

monuments on the wall .about 1.8m high
Laser tracker .

• The floor and wall of storage rings tunnel was
  populated with 3 dimensional monuments

monuments on floor along the girder . intervals
are about 3.5m
monuments on floor along the foot of the wall .
The Cut View of Tunnel
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BEPCII storage rings alignment introduction
Laser tracker station

• 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.

monuments
Laser tracker surveys tunnel network
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BEPCII storage rings alignment introduction
Optical tooling scale for measuring height of
wall monument

• 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.

The leveling staff for measuring the height of
floor monument
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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.

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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.

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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 dont
  satisfied with the requirement, we will readjust
  them.

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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.

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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.

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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.
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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 !