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

Rob Reilly

7/16/08

This is a summary of all the changes, modifications, improvements, etc.
that were done to the Crystal Collimator, from the time it was received
at FNAL from Brookhaven in 2004 to the present date.

More photos and documents can be found at:

[\\\\Beamssrv1\\mechsupt.bd\\public\\Reilly\\Brookhaven_Crystal_Collimator](../../../../../../../../mechsupt.bd/public/Reilly/Brookhaven_Crystal_Collimator)

This is the collimator assembly or device as received from BNL.

![](media/image1.jpeg){width="5.688888888888889in"
height="4.266666666666667in"}

Here is a view of the original RHIC crystal.

![](media/image2.jpeg){width="5.688888888888889in"
height="4.266666666666667in"}

The device as received needed a number of modifications immediately to
make it suitable for installation in the Tevatron. These were performed
in 2004 and the device installed for a run.

This is the device as installed at E-0 in the Tevatron.

![](media/image3.jpeg){width="5.808333333333334in"
height="4.360416666666667in"}

Later the original BNL RHIC crystal was removed, the crystal holding
parts were modified, and a different crystal from Russia was installed,
and the device was installed in the Tevatron for another run.

Here is the Russian crystal.

![](media/image4.jpeg){width="2.696527777777778in"
height="2.933333333333333in"}

This year several modifications were made to the operational
characteristics of the device, and the original crystal was re-installed
inside.

Here is the device as currently configured, waiting at NWA for an
installation opportunity.

![](media/image5.jpeg){width="5.76875in" height="4.326388888888889in"}

Here is a view of the RHIC crystal moving into the beam line.

![](media/image6.jpeg){width="5.804166666666666in"
height="4.3597222222222225in"}

This is an approximately chronological list of all modifications
performed on the device. All drawing numbers referred to in this
document are the last 4 digits of Brookhaven drawings, since no FNAL
drawings have yet been created for this project. At FNAL we have worked
from sketches and marked up BNL drawings for expediency.

1.  E-0 straight section chosen as the installation location. Collimator
    device assembly as received was too wide, would not fit in the
    Tevatron tunnel at E-0 if installed in the original direction, and
    protruded into the aisle if installed in the opposite direction.
    Base plate dwg 5058 was cut off 3.25" so it will not protrude into
    the aisle at E-0, added 4 Keenserts, 4 tapped holes, 4 large holes
    for attachment to the floor.

2.  Linear stage base plate dwg 5056, added 3 tapped holes and 4 thru
    holes, turned the linear stage around so the drive motor wouldn't
    protrude into the aisle at E-0.

3.  added Unistrut parts to base plate for floor mounting

4.  cut off part 5025 from part 5002 because it was in the way for
    turning the drive motor around

5.  added new outer cross support bracket, my design, as substitute for
    part 5025

6.  turned BNL RHIC crystal upside down because of opposite beam
    direction

7.  made new modified bracket to substitute for part 5040, with new
    holes for upside down crystal.

8.  deleted scintillator parts and covers

9.  added flange F800-675T MDC #150034 on top of cross dwg 5002 in order
    to attach ion pump

10. added 300 liter/sec ion pump on top of cross 5002

11. added ½-13UNC swivel bolts to part 5056 linear stage base plate for
    better vertical adjustment

12. added standard tooling ball pads to the base plate for alignment

13. made 3 brackets for Russian crystal, my design

14. removed RHIC crystal, installed Russian crystal

15. repaired inchworm motor, repaired inchworm limit switches several
    times, modified wiring and made ceramic mounting for inchworm motor
    wiring

16. We found that the original linear motion slide was a poor choice,
    because it was a ball screw type, which is not self locking and
    could move under vacuum loading. I substituted a new linear slide,
    Daedal 106004CTEPD1L1C1M1E1, which is a lead screw type, and locks
    itself against motion due to axial loading on the screw, along with
    stepper motor Slo-Syn M062-FC-03

17. added machined spacers ½" thick on Daedal slide top plate 5038 to
    raise up part 5003 cross ½"

18. deleted inchworm motor and related parts for swing motion

19. deleted internal LVDT parts for measurement of swing motion

20. added vacuum feedthru motorized linear actuator with stepper motor
    for swing motion

21. added vacuum feedthru for external LVDT position readback

22. added external LVDT for swing position readback

23. made limit switch mounting bracket for linear actuator, in order to
    have external limit switches, my design

24. made new LVDT mounting brackets for Conflat R458-133 flange, my
    design

25. made new Conflat flange assemblies for swing motion linear actuator
    and LVDT readback, with tapped holes for bracket

26. made 2 connecting links for linear position actuator (swing motion)
    and LVDT readback, my design

27. added viewport MDC VP300 450005 on top for viewing swing motion
    under vacuum

28. crystal was observed to vibrate due to slack mounting design as
    received from BNL, added tapped holes to part 5041 for locking
    screws, which cured the vibration

29. found that swing arm assy 5005 was dragging and producing jerky
    motion, machined off 1/16" on top of part 5032 stationary bar to
    cure this problem

30. machined larger hole in stepper motor mount provided with new linear
    slide, for better access to shaft coupling

31. added locknuts to set screws on shaft coupling

32. changed adjustment screw on top of part 5026 to slotted binder head
    screw, because the original set screw was too small and difficult to
    tighten with a tiny Allen wrench; note next time substitute a bigger
    locknut so it can be tightened with a nut driver over the screw
    head.

33. added lifting eyes to the base plate for installation, to lift it
    into place with an engine hoist

34. substituted a more powerful Slo-Syn stepper motor M063-LE-09E with
    double ended shaft and a hand crank so the crystal can be moved out
    of the beam line by hand if necessary

35. substituted helical swivel shaft coupling 9861T509 on stepper motor
    because straight coupling may have been causing dragging in the
    linear motion

36. added acrylic tube protective sleeves over swing motion actuator and
    LVDT

This is the new linear actuator for swing motion.

![](media/image7.jpeg){width="5.804166666666666in"
height="4.352777777777778in"}

It provides for an angular positioning of the crystal in steps of 1.362
microradians.

It can be hand operated by the thumbwheel if necessary.

This is the new external LVDT and visual position indicator for swing
motion.

![](media/image8.jpeg){width="5.804166666666666in"
height="4.352777777777778in"}

This is a view looking down the viewport at the linkage for the swing
motion.

![](media/image9.jpeg){width="5.76875in" height="4.326388888888889in"}

This is the new linear positioning stepper motor for moving the crystal
horizontally across the beam line. It provides for linear motion in
steps of .00005 inches. Also shown is the hand crank for moving the
crystal out of the beam line if necessary.

![](media/image10.jpeg){width="5.7243055555555555in"
height="4.293055555555555in"}

To use it, simply crank it until the Conflat flange above it hits the
limit switch.

Overall design and operational parameters were established by Dean
Still. Technical assistance was provided by Sali Sylejmani, Al Legan,
Todd Johnson and Scott McCormick. The device is currently in the NWA
tech shop awaiting a suitable access time in the Tevatron, so it can be
installed again.

\* \* \* \* \*