User name R. Michaels
Log entry time 10:31:47 on March26,2005
Entry number 142464
keyword=Left arm scint. efficiency
The T4 rate is slightly higher than the T3 rate. Since T4 measures
efficiency, usually and to 1st order, this raises a red flag. I'm
not aware if anyone checked it, so here it goes. The "bottom line"
is that the scintillator efficiency is acceptably high (98-99%) and
for some reason a lot of T4 are junk. Note, the T1/T2 picture is
Using a randomly chosen production run (2948)...
Examine the trigger efficiency for Left Arm using a plot like this:
And requiring either event type type 3 or 4, and judging if the event is "good" or "bad" from the sum of VDC hits >0 or ==0 respectively.
From Raw Scaler Rates:
T3 raw rate = 174 Hz
T4 raw rate = 194 Hz (--> implies naive inefficiency 53% !!)
Fraction of T3 which are good = 23665 / (3518+23665) = 87%
Fraction of T4 which are good = 70 / (70+2327) = 2.9 %
Estimated Trigger Inefficiency = (0.029 * 194) / (0.87 * 174) = 3.7 %
==> Single scintillator plane Inefficiency = 1.8 %
This is about a factor of 2 higher than experience. But one can do the same cleanup using L.tr.n (# of tracks). Result is
Fraction good T3 = 84 % (have >= 1 track)
Fraction good T4 = 1.5%
Trigger Ineff = 2.0%
Single-plane Ineffic = 1.0%
A 1% single-plane inefficiency is about what I expect.