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Re: "nan" in the energy of the DBCALPhoton
Hi Alex,
This particular section of code was added by Blake recently to try to
improve reconstruction at the end of the module. I'm not familiar
with it -- Blake, can you help Alex?
Indeed it looks like the problem is trying to call pow with a negative
base. That will certainly generate nan.
-Matt
On Jun 30, 2009, at 5:04 PM, Alexander Somov wrote:
>
> Hi Matt,
>
> I have found a few events in the BCAL reconstruction
> where the photon energy is not calculated properly.
> Below is a typical example:
>
> DBCALPhoton:
> x: y: z: px: py: pz: E:
> ----------------------------------------------------
> 56.62 37.97 133.08 0.12 0.08 0.15 0.21
> -9.08 67.51 211.40 -0.06 0.46 1.01 1.11
> -64.92 23.81 306.27 -0.45 0.16 1.67 1.74
> 19.78 -62.68 405.37 nan nan nan nan <---
> 61.69 -31.96 397.37 0.01 -0.00 0.05 0.05
>
> DBCALShower:
> x: y: z: t: E:
> --------------------------------------
> 56.62 37.97 133.08 6.11 0.18
> -9.08 67.51 211.40 5.40 1.04
> -64.92 23.81 306.27 8.38 1.61
> 19.78 -62.68 405.37 11.77 0.51 <---
> 61.69 -31.96 397.37 12.55 0.03
>
> The problem appears at the edge of the BCAL, specifically
> in the DBCALPhoton_factory.cc file where the energy of a
> photon is calculated (for zEntry >= 370.0 ):
>
> double energy = pow( ((**showItr).E - lin ) / scale, 1 / ( 1 +
> nonlin ) );
> lin -0.08144
> nonlin -0.616129
> scale -0.0563619
> **showItr 0.505658 (shower energy)
> energy nan
>
> pow(x,y) is called here with the negative x.
>
> Could you please check the callibration coefficients in the
> DBCALPhoton_factory.cc
> factory (I have no clue how these coefficients have been obtained).
> I would like to finish with the acceptance studies shortly.
>
> Thanks,
> Sascha
>
>
> P.S. Just in case, I put the hddm file with "p eta pi0 pi0" events
> where i have observed the problem to ~/public_html/debug.hddm
>