[Brahms-dev-l] brat 2.24.8

Hello,

I discovered that some very useful setting (FS @ 8A861, AuAu @ 63 GeV) was
problematic at the gtr,DST level (FS track momentum ~ 9999). I thought
that was fixed some time ago but it turns out that the
BrFsGlobalRefitModule could not handle a particular case, namely : D1-D2
on but D3-D4 off. However, since all tracking chambers performed ok, I
want to use the D2 momentum even for full FS tracks (worse resolution but
better than nothing). That was so far fine if one did not use the refit
module. So I looked into it and here is the problem and the fix:

to refit the momentum in the full FS, a seed is needed which is equal to
the arithmetic average (pd2 + pd3 + pd4)/3.
But if D3 and D4 are off, p_ave = pd3 = pd4 = 9999 GeV/c ... not cool!

Fix: I now check the fields; if on, leave p_ave as it is, if 0, then use
only pd2 as a seed. I checked the output, it looks fine (I don't know what
this module does eaxctly with the track lines but the refitted momentum is
finally very close to pd2 for this data set).

I will re-reconstruct gtr and DSTs for this setting.

brat is tagged BRAT-2-24-8.

Djam


-- 
Djamel Ouerdane ------------------------------------------o
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