[Sbs_gems] [New Logentry] Update on APV on UV GEM layer 3

[jeffas at jlab.org]

Logentry Text:
--
In the attached picture I first discovered that APV 7 on fiber 20 (UV layer 3) has a baseline ADC that is around 900, when it should be around 400. I sifted through the log books and found in run 12195, taken during SBS-7, the APV looks fine https://logbooks.jlab.org/entry/3953284. This run was the last run that was already analyzed, that does not show any issue with this APV. I am currently getting the last run of SBS-7 and the first run of SBS-11 from tape to see if the issue happened during the change over. We first see (from runs that were already analyzed) the APV jump to 900 ADC in run 12276 which is after SBS-11 https://logbooks.jlab.org/entry/3949939. We find that in the next day in run 12357 the ADC actually drops down to about 450 ADC, https://logbooks.jlab.org/entry/3951825. Then a couple hours later it goes back to 900 ADC in run 12360, https://logbooks.jlab.org/entry/3951883, and it has been there for the last two days. 

So overall this APV seems to be fluctuating wildly in baseline, but still reading signal fine, which I have never seen before. During access I will try resetting the LV and MPD crates, then re plugging in the APV to the backplane, then replacing it. This APV goes across the upper middle of the layer so it is important to get it working properly

---

This is a plain text email for clients that cannot display HTML.  The full logentry can be found online at https://logbooks.jlab.org/entry/3953312
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/sbs_gems/attachments/20211130/27764edb/attachment-0001.html>