Run 4264, understanding magnetic fields in BRAHMS

From: Ian Bearden (bearden@nbi.dk)
Date: Sat Aug 18 2001 - 06:49:05 EDT

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    Hi all,
    I am not sure how to direct this question, so I go for the broadest possible
    group.
    Run 4264 (which was taken from roughly 0430 to 0530 Sat. GMT, or 1130 Friday
    night to 0030 Sat. morning BNLNST) has, according to the shift report and
    the run index, D2 turned off.  This is great, as it should allow me to
    'tune' the FFS geometry.
    I have looked at some of the data, now, and I find that if I use the run
    data base and the SetMagnetField() in BrModuleMatchTrack, I obtain a field
    value (and here I must confess that I do not remember, and did not check
    whether the message there returns the value of GetField() or GetBdl())
    of -0.106.  This raises the question (at least to me): How do the magnet
    settings get written into the run data base?
    Is there some monitor that measures the current, or is it the current
    setting?
    Also, do we have, at present, any method of checking the fields in the
    magnets?
    
    I realize, of course, that this is not a big problem since 0.1 is not too
    big (only a few percent of the fields we actually use), but I am a bit
    curious as to how this could come about.  Any info is much appreciated.  And
    you should all be happy to know that there are tracks in all TPCs for
    4264...at least the first sequence.
    
    Have a nice Saturday, I hope the weather were you are is as beautiful as it
    is
    here in Birkerød.
    -Ian
    



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