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Archived Messages for CLAS_PHOTON@cebaf.gov: Re: comments on real photon meeting

Re: comments on real photon meeting

Eric Anciant (anciant@jlab.org)
Wed, 20 May 1998 11:36:25 -0400

>
>
> Second, the "4 peaks structure" in the tagger timing spectra
> mentioned in the minutes was seen before. I've seen at least two sets
> of runs where the peaks shifted in time by a several nanoseconds. Only
> one of the peaks yield decent particle ID - the most populous one. In
> the runs I examined, about 2/3 of the non-accidental events were NOT in
> that "good" peak. This was for runs BEFORE the ones mentioned in the
> minutes, namely runs between 11043 and 11232. I sure hope the tagger
> army can figure out what is going on here; I have not tried to look
> into that software myself.

One also has to be sure that the proper calibration constants are in the map
manager
at the time you run recsis for the run that is analysed,
Bad constants can appears as multiple peaks or widened peaks in the TAGR
bank
The constants haven't been always updated right away after we cut the
cables,
or change the TDC modules, sometimes it came one week or 2 afterwards.
That could be sometimes the source of the problems,

I send mails to the clas_photon mailing list everytime I update the
constants
And also results of previous calibrations are posted on the web:
http://www.cebaf.gov/~anciant

regards,

eric

--
Eric Anciant \ anciant@jlab.org \ www.jlab.org/~anciant
Thomas Jefferson National Accelerator Facility, MS 16B,
12000 Jefferson Av., Newport News, VA 23606 USA
fax: (757) 269-6273 \ Day: (757) 269-7680 - (757) 269 7481