[G12] My multiple beam photon study

[Michael C. Kunkel]

Greetings,

I to was curious to know why FSU and myself did not agree, so I looked 
at the entire run range in which had the lepton trigger set, also the 
MorB configuration was the same.

https://clasweb.jlab.org/rungroups/g12/wiki/index.php/TAGR_code#April_1

I noticed an overall difference of 3% from when I used earlier runs. So 
I decided to look run by run and I noticed there was a dependence on run.

For instance compare run 56726 to run 57195 using this
https://www.jlab.org/Hall-B/secure/g12/mkunkel/MULTIPLE_PHOTONS/Plot_1.pdf

BR
MK
----------------------------------------
Michael C. Kunkel, PhD
Forschungszentrum Jülich
Nuclear Physics Institute and Juelich Center for Hadron Physics
Experimental Hadron Structure (IKP-1)
www.fz-juelich.de/ikp

On 31/03/15 20:51, Lei Guo wrote:
> Hi, MK and Michael,
>
> In general I agree with Michael what you are showing is reasonable. 
> The 1-photon-only probability plot shows basically the percentage (for 
> Egamma > 3.6GeV) is about 86.6%+-1% (eyeballing). What Will showed 
> from his ppbar channel is about 87%+-1% (also eyeballing, and he 
> starts from 3.9GeV). There is no difference here. The two plots (you 
> and will) looks dramatically different because of the energy range 
> (x-axis), and because of will shows on the Y-axis from 0 to 100%, and 
> you zoomed in from 80% to 90%. It tells exactly the same story.
>
> For the low energy part (Egamma <3.6 GeV), I think Michael’s 
> explanation is probably right — although I won’t call it trigger 
> efficiency or inefficiency. It’s only inefficient when a event that 
> should have triggered and been recorded did not get registered.
> But even if you compare these two ranges, it’s really a only 1.5% 
> difference. Do you think our systematic uncertainty on the 
> normalization is less than 1.5%? I think in the big picture, we are fine.
>
> But I do agree with MK that his picture is different from FSU, 
> particularly in the low energy part, since it showed opposite trend.
>
> How does Rafael’s results compare with you, particularly for the low 
> energy part?
>
> Is it possible that again this is due to you and FSU are not showing 
> the data from exactly the same set of runs?
>
>
>
>
>
> Lei Guo
> Assistant Professor
> Physics Department
> Florida International University
> Miami, FL
>
> email: leguo at fiu.edu <mailto:leguo at fiu.edu> or lguo at jlab.org 
> <mailto:lguo at jlab.org>
> Office:305-348-0234
>
>> On Mar 31, 2015, at 2:31 PM, Michael Paolone <mpaolone at jlab.org 
>> <mailto:mpaolone at jlab.org>> wrote:
>>
>> Hi MK, All,
>>
>> This looks reasonable, and I think I can explain the energy dependence.
>> The key is that all events have to fire a trigger whose efficiency is
>> dependent on the momentum and angle of the tracks created from the
>> reaction which itself IS photon energy dependent.
>>
>> Look at the 1 photon probability plot and ask how likely is it that that
>> photon is the one that created the trigger.  For very low energy photons
>> the overall trigger efficiency drops, and since we see an event at 
>> all, it
>> becomes more likely that another higher energy photon in the same beam
>> bucket generated the reaction that triggered the event.
>>
>> The sharp jump at 3.6 GeV shows that the event is now more likely to
>> trigger with just that photon (since that's where the primary trigger
>> starts).
>>
>> The downward slope after 3.6 GeV might again be a trigger efficiency
>> effect, where it becomes more likely that we lose small angle tracks down
>> the beam hole which could have fired the trigger.
>>
>> -Michael
>>
>>> Greetings,
>>>
>>> I did not want to show this last night because I thought there was a bug
>>> in my code. But I do not think I have a bug in my code, so I want to
>>> show you what I concluded.
>>>
>>> First of all, my result does not agree with the values found by FSU or
>>> FIU. I actually see a strange dependence on energy. What I am depicting
>>> are plots of the probability of multiple photons within the same bucket
>>> as clasEvent choose ±1.002 ns, meaning the photon energy on the X-axis
>>> of the plots are of clasEvent chosen, which was the best timed beam
>>> photon compared to the average _of_ start times.
>>>
>>> The data used for this is only the 566* runs, which is approximately 7%
>>> of the data.
>>> Please see:
>>> https://clasweb.jlab.org/rungroups/g12/wiki/index.php/TAGR_code#March_31
>>>
>>> --
>>> BR
>>> MK
>>> ----------------------------------------
>>> Michael C. Kunkel, PhD
>>> Forschungszentrum Jülich
>>> Nuclear Physics Institute and Juelich Center for Hadron Physics
>>> Experimental Hadron Structure (IKP-1)
>>> www.fz-juelich.de/ikp
>>>
>>> _______________________________________________
>>> G12 mailing list
>>> G12 at jlab.org
>>> https://mailman.jlab.org/mailman/listinfo/g12
>>>
>>
>>
>> _______________________________________________
>> G12 mailing list
>> G12 at jlab.org <mailto:G12 at jlab.org>
>> https://mailman.jlab.org/mailman/listinfo/g12
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/g12/attachments/20150401/e20d9d5d/attachment-0001.html