②
NOTE: The sides of the chamber are labeled with numbers ① to ④ .
③
③
④   ②
1 ①   ①

2
②
③
21.6 cm
21.6 cm
①
2.6 cm
2.0 cm
2.0 cm
④

3
④
21.6 cm
21.6 cm
③
21.6 cm
19.1 cm
②
2.7 cm
①
19.1 cm

4
④
①   ②
③

①
5 mm
4 mm
2 mm
9 mm
②
13 mm
25 mm
9 mm
5 mm
5
5 mm
③

6
APV cards have dimension of 66mm x 50mm x 1mm, and 24mm of the 66mm length of the card extends beyond the edge of the frame.
④
③   24.1 cm ①
②

7
The figures below show more details of APV cards dimension and spacing.
7 mm
7 mm 7 mm
5 mm

8
The corner of ③   and ④ can be considered as a relatively safe spot to use for securing the support frame. Due to small size of frame and very sensitive circuitry, any drilling on the frame is strongly discouraged.
④   ④
③

9
①
④
③
These are relatively safe spots to use for securing the support frame.
Drilling on the frame is strongly discouraged; it can damage the chamber.
④

10
The star-shaped points, marked with blue boxes, can be used as markers for surveying the GEM detector.
Care must be taken to avoid damaging the adjacent connectors.