Pre-Survey

The plate is pre-surveyed outside the magnet, including both point markers and sticker targets. The survey points on the surface of the plate are used to define the horizontal plane. Survey points 1 & 2 are used to define the 45 degree line and the origin. All markers are recorded in the coordinate system thus defined.

Setting Location and Stops

1. Three pointers are located at position 3, 6, and 7, which are the locations close to the three support points.
2. Remove the safety bushings from the front of the rails.
3. The plate is positioned inside the magnet on the support arms.
4. The top of the three pointers is used to adjust the height and levelness of the plate.
5. The same three points (as well as the sticker targets) are used to set the location of the stops (motion along the rails). The X & Y deviations reported by the survey need to be converted into movements along the rails. The front stops should be totally loose. Set the position using the back stops to hold the plate in place. Finally, the front stops should be set against the pillow blocks, locked in place, and the position rechecked. Make sure the stops are oriented correctly (not tilted at an angle) so the plate slides in and out smoothly.
6. Finally, the position across the rails is set with the threaded knob. Loosen the 4 securing bolts first (two by enclosure window and tow at the inner bottom of the back pillars). The X & Y deviations reported by the survey need to be converted into movements perpendicular to the rails.
7. The final relative orientation of markers 3, 6, and 7 gives information about the rotation of the plate. There is no easy way to adjust this, the information is just recorded for future use in positioning the detector in the analysis.
8. Measure the distance from the face of the stops to the face of the end plate that holds the safety bushings. The safety bushings will need to be machined.

Coordinate System Rotation:

For outer and inner arm, y’ is along the rail, with positive toward the magnet and x’ is perpendicular to the rails with positive towards the outer wall.

For the inner arm Dy’ = Dy cos(30) + Dx sin(30) and Dx’ = -Dy sin(30) + Dx cos(30)

For the outer arm Dy’ = Dy cos(30) - Dx sin(30) and Dx’ = Dy sin(30) + Dx cos(30)

Final Location Measurement

This part has not been tested yet. The sticker targets and possibly pointers at locations 6 & 7 can be used to verify the location of the small plate as viewed from +Z. It is hoped that the marker at the back edge (#15) or a future additional marker nearby might also be visible from the –Z side.