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TPC QA pre run 2025 cosmics
Updated on Mon, 2025-05-26 11:55. Originally created by videbaks on 2025-05-08 10:19.
Summary of pre run cosmics 5/8/2025
The information is in chronological order
-----------
Summary from FV on 5/2/2025
I summarizes runs for the cosmics we took and documented when problem occurred.
excel file
When I look at when things went bad- two cases but not noticed for long time it seems to have happended after a long break ours magnet trip magnet taken down. The bad noise only appeared after such period.
I one of the cases there was a pedestal run done, and initial runs had only little nosie but subseqy=uent more
(, but 3rd run after that would always be still bad.
fter a (on 29 after a ped run I request it was good until we stopped.
It seems to me that this is a warmup-up issue. Is it poiisble that more power is delivered to 3+4?
or something like that just a thought.
response from Tonko after investigation 5/8/25
---------
here seems to be a shift in pedestals of 3-4-5 ADC counts for
5/26/2025
Checkout of TPC in cosmic fter restart
Number of issues, mostly recognized by Flemming and noted here by Tonko
1) Outer Sector S12: Very high signal in timebins 18-20.
It is super high (ADCs>500). This looks caused by the GG.
I reloaded GG params but made no difference.
Should try to power-cycle it.
2) Inner Sector iS19: peak at timebins 39,40.
Also seems to be caused by the GG pickup and it didn't go away
after I reloaded the GG.
3) Noisy FEE in Outer S10.
Damn, this is a problem with duplicate FEE IDs #23 (likely broken pin or not well inserted into the padplane) causing a mess.
Not sure what to do? Let me think a bit more.
4) 3 random pads of Inner (iS11, iS12 and iS18) are very high and flatlined across the tb. Obviously dead. I think I killed them
in the gain file.
Summary of pre run cosmics 5/8/2025
The information is in chronological order
-----------
Mail from 3/29
The sequence was the following
good up until run 87017 8:26
then some misc activity in the hall
87013 was first pedestal run after the access.
87026 first cosmic run \ reasonable good but signs of noise apparent in RDObyte plot
by run 87039 really bad (2014):
stayed bad until morning when I requested a pedestal run at the meeting.
At the first run after the pedestal run it was ok. and still is now (16:30 Saturday).
I look a bit more and it seems it is not just noise in the adc spectrum, but gives rise to to increased #clusters as observed in some of the #clusters per sector (inner).This is unlikely a problem for lasers and cosmics.
We need to think about this and discuss how to isolate the problem.
Observations:
What is common for sector 3 and 4 as the seems to go bad together.
--- ideas RDO power supplies sharing
--- gating grid noise.
Is it not true that for iTPC there is no timebin dependent pedestal so strange noise patterns could disturb values uploaded ?
Is there evidence from the data from the pedestal runs if it is a shift in pedestal, and increase width (i.e noise level).
It is spread out across all timebins, and we see it across all pads and rows.
A particular feature seems to be a peak in the middle of the time spectrum.
Summary from FV on 5/2/2025
I summarizes runs for the cosmics we took and documented when problem occurred.
excel file
When I look at when things went bad- two cases but not noticed for long time it seems to have happended after a long break ours magnet trip magnet taken down. The bad noise only appeared after such period.
I one of the cases there was a pedestal run done, and initial runs had only little nosie but subseqy=uent more
(, but 3rd run after that would always be still bad.
fter a (on 29 after a ped run I request it was good until we stopped.
It seems to me that this is a warmup-up issue. Is it poiisble that more power is delivered to 3+4?
or something like that just a thought.
response from Tonko after investigation 5/8/25
---------
here seems to be a shift in pedestals of 3-4-5 ADC counts for
2 different but specific FEEs: 1 in Sector 3, 1 in Sector 4.
All timebins of 1 SAMPA chip (this 1/2 a FEE) jump up and
stay up. No idea why. Could be malfunctioning SAMPA.
The regulators are shared between the 2 SAMPAs so that's
not the reason. In any case, not much we can do.
You can see the odd shape of the cluster charge step with a sharp
narrow peak in the middle: the cluster finder treats this as 1 biiiig
cluster spanning 400ish timebins and calculates the mean timebin at
~half of the range i.e. 200.
E.g. run 26082041.
I'd like to let it be like this for a day of the next run (I assume a few days
of cosmics) and I'll take another look. But the way out is to simply
kill those FEEs. The reason I don't want to do it just now because
I am curious and I want to write some code which compares pedestal
runs "in vivo" looking for this pedestal jump.
FV/ you can also see in the tpcclustertimewidth that there are many assigned 30 i.e largest values
and matches what Tonko say.
FV/ you can also see in the tpcclustertimewidth that there are many assigned 30 i.e largest values
and matches what Tonko say.
5/26/2025
Checkout of TPC in cosmic fter restart
Number of issues, mostly recognized by Flemming and noted here by Tonko
1) Outer Sector S12: Very high signal in timebins 18-20.
It is super high (ADCs>500). This looks caused by the GG.
I reloaded GG params but made no difference.
Should try to power-cycle it.
2) Inner Sector iS19: peak at timebins 39,40.
Also seems to be caused by the GG pickup and it didn't go away
after I reloaded the GG.
3) Noisy FEE in Outer S10.
Damn, this is a problem with duplicate FEE IDs #23 (likely broken pin or not well inserted into the padplane) causing a mess.
Not sure what to do? Let me think a bit more.
4) 3 random pads of Inner (iS11, iS12 and iS18) are very high and flatlined across the tb. Obviously dead. I think I killed them
in the gain file.
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