"nan" in the energy of the DBCALPhoton

[Alexander Somov <somov@jlab.org>]

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