[G12] My multiple beam photon study

Thu Apr 2 13:22:57 EDT 2015

Hi,

To answer Lei’s question on how my results compares with MK’s, I have attached my results and MK’s for run 56669. I did not use error bars but the results look the same, nonetheless. 

I wanted to post this on the wiki page, but it seems that my jlab password does not work anymore. Is anyone else having this issue?

Best regards,

Rafael

> On Apr 1, 2015, at 7:57 AM, Michael C. Kunkel <mkunkel at jlab.org> wrote:
> 
> 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 <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 <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 <http://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 Â±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 <https://clasweb.jlab.org/rungroups/g12/wiki/index.php/TAGR_code#March_31>
>>>> 
>>>> --
>>>> BR
>>>> MK
>>>> ----------------------------------------
>>>> Michael C. Kunkel, PhD
>>>> Forschungszentrum JÃ¼lich
>>>> Nuclear Physics Institute and Juelich Center for Hadron Physics
>>>> Experimental Hadron Structure (IKP-1)
>>>> www.fz-juelich.de/ikp <http://www.fz-juelich.de/ikp>
>>>> 
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>>>> 
>>> 
>>> 
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>> 
> 
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