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User name R. Michaels
Log entry time 15:20:23 on December18,2008
Entry number 253910
Followups:
keyword=PVDIS R-HRS Detector statusFor PVDIS parasites ...
Here's a breakdown of the R-HRS detector status from my POV for
run 20211.
The problems can be chased in the January down.
S1 and S2 TDCs look ok.
S1 ADCs look ok but need a log plot to see the data.
This because pedestal suppression is turned off (-> no big deal)
S2 ADCs seem to be unplugged or a wrong detmap.
VDCs -- look great.
Preshower -- all pedestals look pretty good. Most blocks have
no signals and the ones that do look low (see fig 1), but it
might be normal.
Shower -- Some large offsets, it could be due to the outputs of
the summing-8 modules. E.g. for the ADC with a 100 ohm input,
50 fC per bit and 400 nsec gate (yes, it's pretty wide) an offset
voltage of 37.5 mV puts the pedestal at channel 3000. Not sure if
that's the problem but we can try swapping various things to check.
Shower problems:
First 8 channels mostly saturated (ADC = 16383 = 2^14-1).
Second 8 are narrow pedestal, between 390 to 630, width = 3 chan.
There is no hint of a signal. Looks unplugged to me or HV off ?
Third 8 are a mixed bag. Some fairly normal (fig 2, this is the
17th channel) others saturated, and others narrow pedestal.
Fourth 8 are narrow pedestal (like 2nd group)
Channels 33 - 47 (using Fortran indexing that starts at 1) look
like normal shower blocks that I've seen for years. A pedestal
and a tail to higher ADC values.
Channels 58 - 63 look mostly ok but some saturation.
Channels 64 - 80 look like narrow pedestal. No signal at all.
Edit: Ramesh tells me the last of each group of 16 are not
plugged in, and that 65-80 (F idx) are not plugged in.
All per the plan, need to check this.
The problems seem to group in groups of 8. I suspect some
sum-8 modules have an offset, and others are unplugged or
there is a detmap misunderstanding.
Conclusion is we're not ready for prime time.
FIGURE 1
FIGURE 2
