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Re: tagger field map



Dear Sascha,

    The number in table 4.2 was calculated for the two dipole tagger. It is 
not correct for the single magnet tagger.  If we don't want to change the 
tagger hall design, we should shift the tagger downstream by ~20 cm.


Cheers

Yang



----- Original Message ----- 
From: "Alexander Somov" <somov@jlab.org>
To: "Richard Jones" <richard.t.jones@uconn.edu>
Cc: <halld-tagger@jlab.org>
Sent: Friday, January 09, 2009 3:53 PM
Subject: tagger field map


>
> Hello Richard,
>
> The magnetic field map in the tagger hall seems
> to be shifted by a few cm in the MC.
>
> According to the table 4.2 in the technical design
> report (updated for the review), the position of
> 12 GeV electrons at z=26.301 m should be x = -4.7576 m.
> However, I get x = -4.803 m, see the plot attached.
> Are the numbers in the table 4.2 correct ?
>
> I used the same reconstruction code as before but just
> replaced the magnetic field map (do I need to shift the
> map ?)
>
> Could you please check. I want to finish with updating
> geometry asap.
>
> Thanks,
>        Sascha
>
> P.S. The full-energy deflection angle in the magnet is
> correct, 13.4 deg.
>
>