[Sbs_gems] Good news: Module 7 is fine, efficiency drop was caused by a typo in the database

[Andrew Puckett]

From: Sbs_gems <sbs_gems-bounces at jlab.org> on behalf of Gnanvo, Kondo (kg6cq) <kg6cq at virginia.edu>
Date: Wednesday, December 8, 2021 at 2:23 PM
To: jeffas at jlab.org <jeffas at jlab.org>, sbs_gems at jlab.org <sbs_gems at jlab.org>
Subject: [Sbs_gems] [EXTERNAL] RE: [Revised Logentry] Cosmic run 12663 analyzed for GEMs
Hi Sean, all
After the cosmic run this morning, I am less convinced that we are dealing with window collapse issue, unless it self-corrected like Nilanga suggested but that was not what my experience with this problem in the past.

If it the entrance window collapsed, we will definitively see the effect on the APV time sample distribution so other than the possibility of mapping mismatch, I am wondering if we are starting to see some effect on negative pulses in the analyzed data.

On the plots you presented this morning with “raw APV” before and after the drop started, you can see two APV frames that I put in the square boxes for the after drop situation,

If one can argue that the one on the green box has the signature of a background hit, it is difficult to make the same argument with the second on the red box because it would means that the first APV25 time sample of this hit which would be the only one that fall in the time window frame started with an ADC value of 800 which is huge and unlikely in my opinion, however, this is something you could get with the APV polarity flip.

Of course one cannot draw conclusion from a single event like that, so I would suggest to look at a couple more raw data events before and after the efficiency drop and verify if there are ore instances of this kind of event after the drop w.r.t to before

One can also look at the non-zero suppression raw APV (every 100 events) and do similar analysis than what Xinzhan has been doing to quantify and compare the two situation.

It might as well be that for some reason, the polarity flip became more severe for the APV of these modules and started affecting the hits of interest more than previously. Again, this is jus another thing to look at in my view

Best regards
Kondo

From: Sbs_gems <sbs_gems-bounces at jlab.org> On Behalf Of jeffas at jlab.org
Sent: Wednesday, December 8, 2021 1:35 PM
To: sbs_gems at jlab.org
Subject: [Sbs_gems] [Revised Logentry] Cosmic run 12663 analyzed for GEMs

Cosmic run 12663 analyzed for GEMs<https://logbooks.jlab.org/entry/3958982>

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Lognumber 3958982<https://logbooks.jlab.org/entry/3958982>. Submitted by jeffas<https://logbooks.jlab.org/user/jeffas> on Wed, 12/08/2021 - 13:34<https://logbooks.jlab.org/entries?start_date=1638984867&end_date=1638992067&book=HALOG>.
Last updated on Wed, 12/08/2021 - 13:34
Logbooks:
HALOG<https://logbooks.jlab.org/book/halog>
Attached Files:
[PDF icon]summaryPlots_12663_BBGEM_ped_and_commonmode_shift.pdf<https://logbooks.jlab.org/files/2021/12/3958982/summaryPlots_12663_BBGEM_ped_and_commonmode_shift.pdf>
[PDF icon]summaryPlots_12663_bb_gem_for_shiftcrew.pdf<https://logbooks.jlab.org/files/2021/12/3958982/summaryPlots_12663_bb_gem_for_shiftcrew.pdf>
[PDF icon]summaryPlots_12663_bb_gem_basic_shift.pdf<https://logbooks.jlab.org/files/2021/12/3958982/summaryPlots_12663_bb_gem_basic_shift.pdf>

We took a short cosmic run (800k events) to reduce background to investigate the low efficiency on UVa XY module mid-upper (module 7). We see that even with cosmic data all distributions look normal before tracking. Unfortunately there are not enough tracks to fill out the tracking plots in a significant way. Therefore this does not have the "smoking gun" of a flat peak time sample distribution that Kondo was looking for. Now we wait to see if Andrew can flip the axis in the database and that fixes things.
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