University of Wisconsin-Madison Transfer Line Studies James N. Bellinger University of Wisconsin-Madison 12 December 2008

Summary No Cocoa yet Hand fits show relative rotation among Endcap disks Can identify backwards DCOPS James N. Bellinger 12-December-2008

Description 6 Transfer lines at 60 degree intervals around the outside of the detector 12 DCOPS on each Transfer line 4 on each Endcap 4 on selected MABs 2 Lasers on each Transfer line Call them the Plus and Minus lasers 72 DCOPS in all, with 144 readings Oriented so the 1/3 CCD pair measure Rφ, 2/4 pair measures radius James N. Bellinger 12-December-2008

Problems A few DCOPS were unreadable Sometimes LV to Barrel DCOPS was off Lasers were shadowed in places: no signal Laser direction not always adjustable James N. Bellinger 12-December-2008

Layout YB-2 YB-0 YB+0 YB+2 Laser Laser ME-4 ME-3 ME-1 ME+1 ME+2 ME+3 James N. Bellinger 12-December-2008

Cocoa Model of Transfer Lines Is not ready yet. James N. Bellinger 12-December-2008

Data Selection From CRAFT run Select interval with field at 3.8T in which laser directions don’t drift much Select interval with field off ditto (CRAFT data taking was two runs: would have been a single run if the power hadn’t failed) Plot the distribution of mean values subject to quality cuts Background area <300000 pixel x counts Signal area>0 and <500000 Sigma >39 pixels and < 220 Mean>0 pixels and < 2048 James N. Bellinger 12-December-2008

Endcap-only study For each magnetic field state For each Endcap, use the laser at that end For each Transfer line, use the 4 DCOPS Reorient the CCD information to match DCOPS mounting For each CCD, fit the means at the 4 DCOPS and find the residuals Average the residuals of opposite pairs of CCDs Interpret these residuals as displacements of the DCOPS and plot them James N. Bellinger 12-December-2008

Plus Endcap DCOPS displacements Vectors plotted to show dX Ring diameter is not relevant Largest vector has length given in the title Vectors at center average of rest, to estimate disk displacement James N. Bellinger 12-December-2008

Minus Endcap DCOPS displacements ME-1 and ME-2 show relative rotation about .5 mrad ME-1 and ME-2 show relative dislocation of about 3mm James N. Bellinger 12-December-2008

Change with field Change in relative displacement with field is mostly radial ME+3 and ME+2 move oppositely (EXPECTED!) The disk YE+2 bends, and the DCOPS positions are cantilevered James N. Bellinger 12-December-2008

Change of Raw Beam Positions ME-4 ME-3 Difference between field on and off for Minus endcap at each station, as a function of position (φ) around the disk. ME-4 next to laser: little change ME-3: about 3mm ME-2: about 3mm ME-1: about 8mm ME-2 ME-1 James N. Bellinger 12-December-2008

Connecting Across Select data from 16-August Not all profiles are usable For Transfer Line 1, only connect with Up/Down CCD data (Rφ) Both lasers reach across for Line 1, so I can compare their results directly James N. Bellinger 12-December-2008

Example of Transfer Line Profiles CCD0 CCD0 data reaches across, but CCD1 gets blocked somewhere CCD1 James N. Bellinger 12-December-2008

DCOPS orientations This one is odd: DCOPS directions data suggests other direction DCOPS directions aren’t the same along a line James N. Bellinger 12-December-2008

Deviations from Linear Fit 10 Stations had data for Up/Down CCDs (not always both of the pair) for both laser beams Estimated laser tilt Averaged CCD values if both present Corrected for laser tilt if not Fit for each laser and plotted the deviations from the fits James N. Bellinger 12-December-2008

Oddity RMS=3.3mm Difference is huge at this point. If I assume the DCOPS is backwards, the points fit very well. RMS=1.0mm Difference in deviations found using Plus and Minus laser fits James N. Bellinger 12-December-2008

Conclusions When the beam is unobstructed we can get useful information out of the system Once mounting variations are understood we’ll have a better measure of the resolution of the system James N. Bellinger 12-December-2008