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User name V. Sulkosky
Log entry time 16:05:31 on November 05, 2008
Entry number 246929
keyword=Preliminary Left HRS Detector Position Measurements
Last week I made some measurements of the detector z positions with
respect to the S1 plane. Using S1 is convenient since this detector's
location with respect to the VDC is fixed and unchanging.
In reality, I could not measure each detector with respect to S1
individually
so instead I measured various distances along the
detector
stack including the thickness of A1 and the gas Cerenkov.
I did not remeasure the RICH, since Youcai did this earlier. The
detectors were centered last week and all y (transverse direction)
distances were zeroed.
The following were measured from the detector's front plane to their
back planes:
Thickness of A1: 29.2 cm (11.5")
Thickness of Gas Cerenkov: 90.2 cm (35.5")
The gas Cerenkov was difficult to measure due to it's irregular shape. I
am
sure I can check my numbers against earlier measurements.
Detector Location Position relative to S1 (m) Z position (m)
-------------------------------------------------------------------------
S1 position 0 1.2873
A1_front 0.0762 1.3635
A1_back 0.3683 1.6556
GC_front 0.4318 1.7191
GC_back 1.3335 2.6208
S2m front 1.8542 3.1415
I was only able to measure the distance from S2m frame to the GC_back
plane.
I have some notes from Rob Feuerbach that there is a 1"
distance between the active region of S2m above the frame position.
Using 1.8542 m distance between S1 and S2m, the time-of-flight between
the two detectors is about 6.2 ns.
I will update the detector databases with these new numbers.
A copy of this log entry has been emailed to: jiang,ycwang,chiran,brads