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User name Jin Huang
Log entry time 21:13:41 on November 1,2008
Entry number 246019
This entry is a followup to: 245979
keyword=MWDC Position survey with Bigbite magnets off run # 2635With bigbite magnets off, shadow of bigbite sieve is observed on MWDC. By back tracking tracks to virtual planes parallel with 1st chamber, carbon foils image could be seen at 2.75m away. By focusing on the middle carbon foil, I can tell the relative position of carbon foil in MWDC coordinate system. So MWDC position in target coordinate system could be calculated:
Horizontally, MWDC 1st chamber center point is 2.78m away from target center. As well MWDC center point is 6cm higher than target.
1st picture : shadow of bigbite sieve on MWDC. Vertext cut on the 3rd carbon foil from upstream.
2nd picture : back projection of tracks on a virtual plane, which is 2.75m away & parallel with 1st chamber
FIGURE 1
FIGURE 2
