The dark current alarm continued to go off for EW1PP5TT27.  A snap shot of the EPD gui can be seen at:

Figure 1: EPD GUI showing tile dark current

The current on this tile tends to bounce around, an example of the bounce is shown in Figure 1.  If we look at the dark current versus time for this tile, we see:

Figure 2:  Dark current for the problem tile is shown on the left.  Dark current for a "good" tile at the same eta (and thus receiving the same average "light" current when the beam is on) is shown on the right.

Zooming in, we can see the date a bit better:

Figure 3: Zoom in of EW1PP5TT27 to see that the incident took place around 4/08.

Looking at the IV scans prior to the incident:

Figure 4: IV scans prior to incident on 4/8, things look normal for all SiPMs associated with this SS (L 04/05/2018 R 04/07/2018).

Figure 5: IV scans after to incident on 4/8, things look normal for all (other) SiPMs associated with this SS (L 04/08/2018 R 04/25/2018).

We should also look at the channels on the same FEE:

Figure6: Channels all on the same FEE (and thus the same SiPM card) as our problem channel on 4/5 (L) and 4/25 (R).  As noted without evident in Figure 5, the other channels look fine.

The full files for these scans can be found at:
drupal.star.bnl.gov/STAR/system/files/ivout_ewpptt_ivhist_run_04_05_15_58.pdf
drupal.star.bnl.gov/STAR/system/files/ivout_ewpptt_ivhist_run_04_07_00_11.pdf
drupal.star.bnl.gov/STAR/system/files/ivout_ewpptt_ivhist_run_04_08_15_18.pdf
drupal.star.bnl.gov/STAR/system/files/ivout_ewpptt_ivhist_run_04_25_12_07.pdf

And grouped by FEE:
drupal.star.bnl.gov/STAR/system/files/ivout_tuff_ivhist_run_04_05_15_58.pdf
drupal.star.bnl.gov/STAR/system/files/ivout_tuff_ivhist_run_04_25_12_07.pdf

The dark current plots can be found at:
drupal.star.bnl.gov/STAR/system/files/DarkCurrent04262018.pdf  (small plots)
drupal.star.bnl.gov/STAR/system/files/DarkCurrentBig04262018.pdf (big plots)

The code (switch txt to C) is at:
drupal.star.bnl.gov/STAR/system/files/darkcurrentconvert.txt
drupal.star.bnl.gov/STAR/system/files/DrawDark.txt
drupal.star.bnl.gov/STAR/system/files/ivscanconvert_1.txt
drupal.star.bnl.gov/STAR/system/files/DrawIVhistos_1.txt

The "convert" code runs on the ascii files produced by Tonko's script, which appear on daqman at:
/RTS/data/epd/

They create .root files where the histogram names are ew/pp/tt and the titles are the tuff, fee ch.  For the dark current, I then hadd all the histograms together in order to have one set of histograms that span the entire range.

The "Draw" codes well, make the multipage pdfs.  For the iv scan I only draw a single scan at a time, for the dark current I draw over an entire time range.