[Halld-cal] [EXTERNAL] BCAL timing in 2017 and 2018

[Sean Dobbs]

Hi all,

The discrepancies that Jon Zarling has seen between runs in the
30000's and 40000's
(https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_JeffersonLab_HDGeant4_issues_138&d=DwIGaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=qOykDDW07dxNIz2gqzRW_0sRJeff1E30DnojDqga1Jo&m=iNISuAiRFqaFkD6Hch0Zbw9Io3yHOMMFzYZSYQgYlO4&s=2JJyyx0LNNuKequwq6r_3-LGkDYA2PeBV9NtchGFMTY&e= ) were brought up
in today's HDGeant4 meeting.  Differences between run periods are
surely due to some difference in the calibration constants used.

I wonder if someone could remind me what the difference between how we
did timing calibrations in 2017 and 2018 was?  I noticed that
/BCAL/tdiff_u_d had non-zero values in the 30000's and was zeroed out
in the 40000's.
Frankly, I can't remember what was done right now and couldn't find
out where it was written down.   This is relevant to the simulations
since this table is applied when calibrating digihits, but isn't
compensated for in mcsmear.  But maybe I'm not remembering an
important piece to the puzzle...

Cheers,
Sean


ifarm1402.jlab.org> ccdb cat BCAL/tdiff_u_d:41509:mc | head -n 15
+------------+
| tdiff_u_d  |
| double     |
+------------+
| 0.0        |
| 0.0        |
| 0.0        |
| 0.0        |
| 0.0        |
| 0.0        |
| 0.0        |
| 0.0        |
| 0.0        |
| 0.0        |
| 0.0        |
<SNIP>
ifarm1402.jlab.org> ccdb cat BCAL/tdiff_u_d:31001:mc | head -n 15
+------------+
| tdiff_u_d  |
| double     |
+------------+
| 0.3226     |
| 0.3226     |
| 0.3226     |
| 0.3226     |
| 0.1294     |
| 0.1294     |
| 0.1294     |
| 0.1294     |
| -0.1444    |
| -0.1444    |
| -0.1444    |