[G12] Beam Intensity vs MOR rate - G12_wiki

[Eugene Pasyuk]

Gflux was not corrected for anything and I don't see what is there to 
correct.
This is a misconception that the live time correction has been applied 
twice. It is true that g11 discovered necessity to apply additional rate 
dependent correction to the cross section. In fact g11 was the only run 
that had to do that.
EG3 was running with very high intensity as well I am not aware they 
needed to do something similar to what g11 did.
I believe the problem is not in the live time but in the rate dependent 
trigger inefficiency and it turned out that this correction 
quantitatively is similar to the live time correction. G11 had other 
trigger inefficiency corrections as well.

Do you need to apply additional corrections to g12 cross sections? I 
don't know the answer. This has to be studied.
Just to remind you, photon flux is just one out of several ingredients 
for the cross section. You also have to look at yield extraction, 
acceptance, trigger efficiency etc.. The hardware trigger setup for g12 
was completely different compared to g11.

-Eugene

On 02/08/11 10:03, Paul Eugenio wrote:
> Hi Eugene,
>
> We are looking into several issues we have regarding cross section estimates.  One concern we have is with the photon normalizations.   I agree that the MOR is not the viable estimate of any intensity depend sag to the live time.  G12 ran with the highest photo intensity of any run, and earlier studies using g11 data showed a gflux calculated live time which had a dependence on the beam flux.    In order to correct this, the live time corrections where applied twice (as shown by M. Williams).    I do not know if gflux code was corrected or if it needed to be corrected.   Should we apply this correction twice for g12?
>
>
> --
> Prof. Paul Eugenio
> Florida State University
> Department of Physics
> Tallahassee, Florida,  USA 32306
>
> (850) 644-2585
> eugenio at fsu.edu
>
>
>
> On Feb 8, 2011, at 9:38 AM, Eugene Pasyuk wrote:
>
>> We also have individual EPICS scalers for every tagger PMT.
>> They are better monitor than MOR.
>>
>> -Eugene
>>
>>
>> On 02/08/11 09:33, John Price wrote:
>>> Sounds like we need the output of gflux as a function of beam current...
>>>
>>> On Tue, 2011-02-08 at 06:29 -0800, Eugene Pasyuk wrote:
>>>> MOR rate is not reliable intensity monitor. It is logical OR, it is NOT
>>>> arithmetic sum of all counters.
>>>> It saturates and eventually goes down when you increase flux.
>>>>
>>>> -Eugene
>>>>
>>>>
>>>> On 02/08/11 09:24, Paul Eugenio wrote:
>>>>> Hi,
>>>>>
>>>>> I dug out the data from the beam intensity study which was done during the run.    Performing a linear fit to the first few points shows that at 60 nA the MOR rate sags by about 8%.
>>>>>
>>>>> http://clasweb.jlab.org/rungroups/g12/wiki/index.php/Beam_Intensity_vs_MOR_rate
>>>>>
>>>>> --
>>>>> Prof. Paul Eugenio
>>>>> Florida State University
>>>>> Department of Physics
>>>>> Tallahassee, Florida,  USA 32306
>>>>>
>>>>> (850) 644-2585
>>>>> eugenio at fsu.edu
>>>>>
>>>>>
>>>>>
>>>>>
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