[Halld-cal] BCAL segmentation

[David Lawrence]

Just to be clear, Eugene referred me to the definition on the link below 
when pointing out my error.

http://en.wikipedia.org/wiki/Irinia

Sorry again Irina.
-Dave

On 4/4/11 1:43 PM, David Lawrence wrote:
> That sounds much better than what Eugene said it meant!
>
> Sorry for the typo Irina. I'll try and be more careful in the future!
>
> -David
>
> On 4/4/11 1:35 PM, George Lolos wrote:
>> The ancient Greek name, which also the modern Greek, is Irini (mean
>> peace), so we know what we're talking about here... :-)
>>
>> George
>> On 3-Apr-11, at 7:51 PM, semenov at jlab.org wrote:
>>
>>> David:
>>>
>>> 2 comments:
>>>
>>> 1. Irina's name is "Irina" and not some other ancient-Greek versions
>>> (with
>>> all my respect to the Greek culture :)
>>>
>>> 2. About to use the fitting function instead calculating RMS: I do agree
>>> that the fitting procedure (with Breit-Wigner convoluted with
>>> Gaussian or
>>> just sum of 2 Gaussians or Gaussian core and some tails) will provide
>>> more
>>> stable result; but we need agreement about what value to use as the
>>> numerical estimator of the resolution. If we use "1-sigma" analog (viz.,
>>> sixty-something percent confidence interval), we will catch the "core"
>>> structure only and will not be sensitive much to the tails, and
>>> definitely
>>> we don't want to do such a thing. I do believe that 95%-confidence
>>> interval will be much more appropriate, but we all should be aware
>>> that it
>>> corresponds to "2-sigma-resolution" if we will make any comparisons with
>>> the "1-sigma" resolutions from Gaussian-shaped spectra.
>>>
>>> So, do we all agree to use from now the 95%-confidence interval as the
>>> resolution?
>>>
>>> Thank you,
>>> Andrei
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>> Hi Irinia,
>>>>
>>>>      Please find my responses below.
>>>>
>>>> On 3/31/11 9:20 PM, stepi at jlab.org wrote:
>>>>> Hi David,
>>>>>
>>>>> plots on the 2nd slide were calculated for the range of z  from
>>>>> -34cm to
>>>>> 30 cm (Near part of BCal).
>>>> OK. This would make things seem more consistent. Your plots looked
>>>> similar to my ~90 degree plot which I believe corresponds to z=0 in
>>>> your
>>>> coordinate system.
>>>>
>>>>> For the RMS calculation I used the same method : TH1D :: GetRMS().
>>>>> For the histogram presented on this slide limits for RMS are:
>>>>> (-15 to 15)  for the histogram "Fine-Segmented" and
>>>>> (-30 to 30)  for the histogram "Summed-in-Towers".
>>>>>
>>>> Looking at the documentation for TH1, it looks like we should be
>>>> calling
>>>> TH1::StatOverflows() prior to filling the histogram if we want the RMS
>>>> to include the tails. I did not do this myself, but will correct that.
>>>> If that is not done, then the RMS will be a (possibly strong) function
>>>> of the histogram limits.
>>>>
>>>>> For the comparison consistency :
>>>>> All these results ( energy resolution, polar angle and azimuthal
>>>>> angle)
>>>>> were obtained under the following conditions:
>>>>> ( "nTrue == 1&&   prim == 1&&   nShow == 1" )
>>>>> that were created as:
>>>>> ......
>>>>>     m_rootTree->Branch( "nTrue",&m_nTrue, "nTrue/I" );
>>>>>     m_rootTree->Branch( "prim", m_primary, "prim[nTrue]/F" );
>>>>>     m_rootTree->Branch( "nShow",&m_numShowers, "nShow/I" );
>>>>>
>>>>> I have few questions to you:
>>>>>
>>>> OK, that may explain part of the discrepancy. In my RMS plot I'm not
>>>> cutting on having only 1 reconstructed shower and I have no cut to
>>>> ensure the primary particle makes it to the BCAL. My events will
>>>> therefore, not be as clean so the tails will be a little larger which
>>>> would blow up my RMS.
>>>>
>>>>> 1. You didn't put the numbers for the RMS on your plots. It's good to
>>>>> know
>>>>> how big the difference really is.
>>>>>
>>>> I can do this, but I don't trust the RMS as a good indicator since
>>>> it is
>>>> so sensitive to the tails. I think we we need to find an appropriate
>>>> fitting function.
>>>>
>>>>> 2. What version of reconstruction code did you use? As I mentioned
>>>>> before,
>>>>> I am using tag version sim-recon-2011-02-02 . Matt recently found the
>>>>> bug
>>>>> in the smear.cc that included in this release.
>>>>> To fix this bug,  the opening lines of SmearBCal should be changed to:
>>>>> ......
>>>>>    for( int m = 1; m<= 48; ++m ){
>>>>>      for( int l = 1; l<= 10; ++l ){
>>>>>        for( int s = 1; s<= 4; ++s ){
>>>>> ............
>>>>> (the l and s loop limits were swapped).
>>>>> For the plots presented on the meeting, the "bagged" version was used.
>>>>> After fixing the bug, the change in the angle and the energy
>>>>> resolutions
>>>>> is not big.
>>>>>
>>>> I used revision 7602 from the repository which looks to still have the
>>>> bug. I'll fix that as well.
>>>>
>>>>
>>>> Regards,
>>>> -Dave
>>>>
>>>>
>>>>> Thank you,
>>>>> Irina
>>>>>
>>>>>> Hi Andrei and Irina,
>>>>>>
>>>>>>       I've start trying to look at the splitoffs issue for the course
>>>>>> vs.
>>>>>> finely segmented readout options in the BCAL. One of my first
>>>>>> steps was
>>>>>> to try and compare resolutions to some plots you showed at the
>>>>>> meeting
>>>>>> this week as a check that I've got the course segmentation set up
>>>>>> correctly. I've not gotten results that seem completely consistent
>>>>>> with
>>>>>> yours. I'd like find the source of the discrepancy. I've put a couple
>>>>>> of
>>>>>> the plots into a PDF that I uploaded to the wiki here:
>>>>>>
>>>>>> http://www.jlab.org/Hall-D/software/wiki/images/7/7f/20110405_bcal_segmentation.pdf
>>>>>>
>>>>>>
>>>>>> My first question is if the resolution plots shown on your 2nd slide
>>>>>> were for the full range of z or, just for some range around 90
>>>>>> degrees.
>>>>>>
>>>>>> Also, how did you calculate the RMS? In my plots, I just used ROOT's
>>>>>> TH1D::GetRMS() method which I believe is limited by the defined
>>>>>> histogram range (-20 to +20 in my case). I would think that by
>>>>>> cutting
>>>>>> off the tails, I would get a *smaller* RMS than the actual, but mine
>>>>>> seems bigger than yours. Any clues as to why?
>>>>>>
>>>>>> Regards,
>>>>>> -David
>>>>>>
>>>
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