**[Brookhaven Crystal Collimator]{.underline}**

**[Alignment Procedure and Fiducial Establishment]{.underline}**

R. E. Reilly

12 July 2004

This document establishes the procedure for initial alignment of the
crystal target element in the collimator, the identification of external
fiducial points, and the final alignment of the collimator assembly as
installed in the Tevatron tunnel. Drawings referred to in this document
are available at:

\\\\Beamssrv1\\mechsupt.bd\\public\\Reilly\\Brookhaven Crystal
Collimator\\BNL drawings

1.  The base plate, drawing 43005058, is set up on a steel table,
    supported with screw jacks, and adjusted so the top surface is
    level. The inner cross 43005003 may be on or off at this step. The
    outer cross 43005002 is off. The crystal target is protected by a
    guard 43005037 until the outer cross is installed. DO NOT TOUCH THE
    CRYSTAL TARGET. IT IS FRAGILE.

2.  The linear stage base plate dwg 43005056 has three swivel bolts for
    vertical adjustment, hereafter known as the "Y" axis direction.
    There are also eight bolts for horizontal adjustment in two axes.
    The long direction of the base plate is the "X" axis, and the short
    side or beam line direction is the "Z" axis. Refer to dwgs 43005103
    and 43005104.

3.  Rotation about the X axis is defined as "roll", rotation about the Z
    axis as "pitch", and rotation about the Y axis as "yaw".

4.  Refer to dwg 43005028. Set the Daedal Linear Slide Bearing Table to
    about the middle of its travel using the hand crank on the motor.

5.  Adjust the swivel bolts and horizontal adjustment bolts of the
    linear stage base 5056 so that the Daedal Linear Slide is level and
    with .500" clearance between the linear stage base 5056 and the base
    plate 5058. Set one side of the Slide parallel to one side of the
    5058 base plate. Adjust the X and Z positioning bolts so the Slide
    is centered on the 5058 base plate in the Z direction, and 3.250
    inches from the end of the 5058 base plate. Check roll, pitch and
    yaw and set each to zero. Snug down all clamping bolts.

6.  Refer to dwg 43005003 inner cross assy, which can be installed now
    if it is not already. It has four flanges of 4.625" diameter and one
    of 6.000" diameter. Ignore the top flange, which is only used for
    hand access. Tweak the roll and pitch so that the tops of the other
    three 4.625" flanges are all in a plane parallel to the 5058 base
    plate. Tighten all clamping bolts to 50-60 inch lbs torque. Measure
    and note the elevation of the three flanges above the 5058 base
    plate. Recheck roll, pitch and yaw of the linear slide, which should
    still be close to zero.

7.  The inchworm motor should be set at its midpoint of travel.

8.  Refer to dwg 43005026. DO NOT TOUCH THE CRYSTAL TARGET. IT IS
    FRAGILE. The crystal target should be adjusted for pitch and yaw so
    it is parallel to the 5027 target bracket.

9.  Scribe a line on the base plate parallel to and 4.250" offset from
    the wall end as a reference beam line. Install the outer cross on
    its six supports. Do not tighten the bellows flanges between the
    inner and outer crosses yet.

10. Using the hand crank, run the slide in all the way so the protective
    cover over the crystal can be carefully removed, the back it out so
    the crystal angle adjustment screw is visible through the 1.33"
    flange on top of the outer cross. Adjust the angle so the crystal
    target is parallel to the 5058 base plate. Tighten the lock nut.
    Measure and note the elevation of the crystal top edge above the
    base plate.

11. The outer cross dwg 43005002 has four flanges of 6.750" diameter and
    one of 6.000" diameter. Ignore the 6.750" flange on top, which is
    only used for hand access. Adjust the outer cross so it is parallel
    to the end of the base plate and the two Z direction flange centers
    are offset 4.250" in the X direction from the end of the base plate.
    Using the outer diameters of the Z flanges, the offset would be
    0.875" to the end. Set the two X direction flanges in line with the
    linear slide, parallel to the side of the base plate. Using the
    outer diameters of the four flanges, set the elevation in the Y
    direction, which should be the same on centerlines as the inner
    cross. Roll, pitch and yaw should be zero. Tighten the lock nuts and
    recheck X, Y, Z, roll, pitch and yaw. Measure and note the flange
    elevations above the base plate.

12. Now the bellows flanges are tightened, all other flanges and pumping
    apparatus installed, and the device is pumped down, baked and leak
    checked.

13. A laser device is installed on a bracket provided, and is calibrated
    with respect to the crystal target.

14. Installation in the Tevatron tunnel -- The collimator is located in
    the E-0 warm straight section, at a Z position to be determined,
    with the outer cross centered on the beam line, and the inner cross
    towards the aisle. Mark the floor through the six base plate
    mounting holes, then move it aside and set six 3/8" Hilti anchors.
    Install six pcs of stainless threaded rod 5" long in the Hilti
    anchors with nuts and flat washers set to about 1-3/8" above the
    floor. Set the collimator assy over the six threaded rods and add
    lock washers and nuts.

15. Tunnel Alignment - The fiducial points are the outer diameters of
    the vacuum flanges on the 5002 outer cross. The Alignment Crew will
    adjust the elevation, X position, roll, pitch and yaw using only the
    nuts in the base plate, then tighten down the nuts. They do not
    touch any of the other clamping bolts on individual parts of the
    collimator assembly.

16. Vacuum Connections - The 5002 outer cross does not move, so the
    vacuum connection spools have the short welded bellows, a 6.75"
    flange and a 6" flange to transition to the adjacent beam tubes.

17. Beam Physics -- The X position of the crystal is read back by an
    external LVDT, with a total available travel of 2". With the linear
    drive fully extended, the crystal face is located 0.500" from the
    beam tube center. It can be retracted up to 2" from that position,
    i.e. 2.5" out of the beam line. As the beam tube is 5" dia. in this
    device, the target is withdrawn completely out of the beam.

18. The angular position is read back by an LVDT inside the vacuum
    chamber, a movement of 0.010" on the inchworm and LVDT corresponding
    to an angular change of 0.842 milli-radians at the face of the
    crystal target. The inchworm has a total available movement of
    0.100" corresponding to 8.42 milli-radians at the target face.

19. If the X drive motor should fail, a hand crank is provided to move
    the crystal target out of the beam.