Hi John, Pete and Adrian,
First of all, I feel a little suprised that among a series of runs that
were taken within a short period of time, there were such a shift. I am
certain that among runs 1642 to 1799, 1703-1713 are the only ones with
different offsets, whatever source they come from and I am certain that
the difference was universal to all paddles in both sector. Nothing
uncorrectable.
not certain about the earlier ABS runs, just plot ttl in pad 0 and zoom in
to see if there are more than one peak. But I suspect, the unpol runs
dominates the statistics anyways.
The 20 channels difference between left and right is also extremely easy
to correct for by adding a constant value to all offsets in one sector.
If it is not correctable in electronics as John pointed out. In fact, I am
suprised again that we did so good that the difference is as small as it
is allowed by the progammable delays. One way or another, I think this
difference needs to be corrected for.
Database probably presents a more elegant solution. Although I believe
offsets, electronics map and so on are changed only once in a while but
after so many back and forth, I support recording them RUN BY RUN. thus it
is easy to go back and tell if one run is crunched with wrong
environments. A little waste of disk space is probably worth it.
Just woke up and thank you very much for the very quick response on a
Sunday.
Chi
P.S., FYI, the little green line in mass spectra plot marks 0.938GeV.
On Sun, 17 Aug 2003, Peter Karpius wrote:
> Chi-
>
> I am glad you pointed this out. I was using runs 1348-1799 for a
> new offset determination. This shift would certainly throw things off. I
> assume the other runs before 1703 and after 1713 have the same offsets?
>
> Pete
>
>
> On Sun, 17 Aug 2003, zhangchi wrote:
>
> >
> > Hi all,
> >
> > I spot a shift in TOF tdc in run 1703 to 1713 against other runs from 1642
> > to 1799. please see the atatched figure. it plots ttl with ntl==0
> > and qwl ==-1 (average TOF tdc channel numbers after offset subtraction, in
> > left paddle 0, generated mostly by electrons).
> >
> > the lower peak at left are runs 1703-1713, the higher peak at right are
> > the rest of the runs in the range quoted above.
> >
> > these are all unpol deuterium runs taken during a few days running.
> >
> > 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.
> >
> > I believe all paddles on both sector are shifted together but need to
> > look at TDC spectra in other paddles to confirm.
> >
> > Just want to let you know this and consider possible effects.
> >
> > Chi
> >
>
> ----------------------------------------------
> Pete Karpius
> Graduate Research Assistant
> Nuclear Physics Group
> University of New Hampshire
> phone: (603)862-1220
> FAX: (603)862-2998
> email: karpiusp@einstein.unh.edu
> http://pubpages.unh.edu/~pkarpius/homepage.htm
> ----------------------------------------------
>
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