[G8b_run] Tagger Sag

[Volker Crede]

Hi all,

Mukesh Saini in our group has just pointed out that there has been a 2007 
NIM paper on the "Energy calibration of the JLab bremsstrahlung tagging 
system" by some CLAS members (S. Stepanyan et al.). Please find a copy in 
the attachment. They describe a tagger energy correction for CLAS which is 
needed to account for a possible sag of the frames holding the E-counters. 
They say there was "corroborating evidence from simulations of the effects 
of gravitational sagging and various possible misalignments of the tagger 
focal plane". Figures 11 and 12 look very similar to our tagger sag plots.

Mukesh has been working on the tagger calibration for g12 and pointed out 
(he believes) that the correction is in the tagger package for g12 and 
possibly for all runs after 2007. According to Mukesh, we can simply look 
into the tagger code and find out what the correction is.

I will have a closer look at the paper over the weekend. Is anybody else 
aware of this publication? I hope it's not just us ...

Best wishes and have a good weekend

    Volker

----------------------------------

Volker Crede
Assistant Professor
Florida State University
Department of Physics
206 Keen Building
Tallahassee, FL  32306  USA

Phone: 001 850 644-2423
Fax: 001 850 644-4478
crede at fsu.edu
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