Hi, Chi!
> It could be a real shift in electronics or due to a temporary change in
> offset file. No way to tell at this moment. It may be useful to save
> offset values with our data ntuple. it takes just another 200 float
> numbers at most into our root file.
This is exactly the reason I was advocating writing these offsets to the
BLAST_physics MySQL database on a run-by-run basis. The SC_TDC_RUN table
contains a field T0 just for this purpose...
So far Peter has been writing these offsets to files once in a while,
on our general assumption that these numbers do not change.
I think it makes sense to write them to the database (once Pete's offset
code is ready I can modify it so that we dump these numbers to the
database, or I can show him an example of how to do that - but we will
have to run this code after every valid run, or integrate it in lrn!).
Then the analysis would just retrieve these numbers and use them for each
run, instead of assuming (like so far) that everything is stable...
Or we could also save them to our root files - but I wanted to point
out that the database alternative has been there waiting for these
numbers, the database was designed for this after a discussion with Tim
Smith who foresaw the need for it a year and a half ago.
Adrian
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