-----Original Message----- From: Winter Peter [mailto:peter.winter@psi.ch] Sent: Friday, May 12, 2006 5:13 AM To: hertzog@uiuc.edu Cc: rmcnabb@uiuc.edu; jblackbu@uiuc.edu Subject: Influence of the gate valve Hi, as I mentioned this week I put together a sketch of the current beamline. I drew the part starting at the center of the last quad until the window flange where the EMC would follow. The sketch is in drawn in a scale of 1:5 and all measures are in mm. Since we have our lst focus in the last quad I start with the extreme case of a muon just touching the wall in the center of this last quad. This muon will reach the EMC if it just hits the edge where the beam pipe is reduced. This is the upper blue line. Now the red shaded area is the reduction due to the current version with the gate valve. You can see that this 'extreme' muon now is stopped by the gate valve. The bottom blue line in comparison shows the most 'extreme' possible muon with the gate valve. From geometry, I calculated the offset x from the wall at the center of the last quad to be x=2.6cm ((50mm-x)/300mm = (105mm-50mm)/693mm). That is with the gate valve as planned until no, we'd only accept the beam if it is more than 2.6cm away from the wall. So if we want to get to the oldacceptance we have to shift the gate valve more downstream by ~20cm. So we have to discuss that because that'll affect John's part, too, since he'll need 20cm less in the adjustment to have the target in the center. Peter
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