Re: "nan" in the energy of the DBCALPhoton

[Blake Leverington <leverinb@uregina.ca>]

Hi Alex,

I've updated the DBCALPhoton_factory.cc file and checked it in with 
better correction parameters and functions that should avoid any 
negative values in the base for pow. There shouldn't be any nan values 
now.  If there is still a problem, let me know. (I think I've checked it 
in properly anyway.)

-Blake

Blake Leverington wrote:
> 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
>>>>
>>>
>>
>>
>