[d2n-analysis-talk] ROOT TH2D Fit Trouble: S1 Timewalk

[David Flay]

Hi all,

I am trying to check on how good the current timewalk factors for S1 are
in my DB, so I plot:

1e+9*(L.s1.lt_c[i]):1.0/sqrt(L.s1.la_c[i])

which puts the TDC variable in nanoseconds.

After drawing this histo (object name = h), I use:

h->Fit("pol1");

The result I get is attached.  I'm trying to figure out how to get the fit
to actually fit the dark band, where the majority of the events are.  If I
use a fitting range, I get 'no fit' -- I get a black line along the
x-axis.

Has anyone had issues with trying to fit such a scatter plot like this
before (in particular, a TH2D)?

Thanks,

Dave


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David Flay
Physics Department
Temple University
Philadelphia, PA 19122

office: Barton Hall, BA319
phone: (215) 204-1331

e-mail: flay at jlab.org
            flay at temple.edu

website: http://www.jlab.org/~flay
              http://quarks.temple.edu
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