Re: "nan" in the energy of the DBCALPhoton

[Blake Leverington <leverinb@uregina.ca>]

Hi Alex,

I'll look at this today.

-Blake

Alexander Somov wrote:
> Hi Matt,
>
> Thanks for the prompt reply and explanations.
> Blake, could you please take a look on this
> reconstruction feature.
>
> Thanks,
>        Alex
>
>
> On Tue, 30 Jun 2009, Matthew Shepherd wrote:
>
>>
>> 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
>>>
>>
>
>