[Frost] Scale factors and dilution factors

[Eugene Pasyuk]

It certainly would be useful for the group if Hideko and Bill share 
their findings with the rest of the FROST folks.

-Eugene


Bill Briscoe wrote, On 02/25/11 06:26:
>
>> From what I got out of looking at Hideko's results, I have certainly seen that is true.
>
> bb
>
> ----- Original Message -----
> From: Eugene Pasyuk<pasyuk at jlab.org>
> Date: Thursday, February 24, 2011 3:50 pm
> Subject: Re: [Frost] Scale factors and dilution factors
> To: frost at jlab.org
>
>> This all makes sens. The result of it there is no universal scaling
>> factor, it depends on many things
>>
>> -Eugene
>>
>> On 02/24/11 15:40, Michael Dugger wrote:
>>> Hi,
>>>
>>> At today's meeting I was not able to describe why the trigger issue
>> might
>>> be important with regards to scale factors and dilution factors. I
>> think I
>>> can do a better job in this email.
>>>
>>> One thing that we are probably all aware of is that the scale
>> factors are
>>> dependent upon angle and momentum. One of the reasons for this phase
>>> space dependence is that charged particles will typically lose more
>> energy
>>> swimming through the butanol target than for the carbon target. The
>>> difference in eloss between the targets can be fairly large. As a
>>> test, I ran a few events looking at the momentum differences at fixed
>>> eloss corrected momentum and lab angle, and found that a 500 MeV/c proton
>>> at 27 degrees can lose from about 14 to 57 MeV/c in momentum when
>>> originating from butanol, whereas the same proton event originating
>> from
>>> the carbon target will lose about 19 MeV. This means that the CLAS seen
>>> kinematics will be different dependent upon which target the event comes
>>> from. From the small number of test events, I found that the proton
>> events
>>> (500 MeV/c protons at 27 degrees) coming from the carbon target hit
>> TOF
>>> paddle 22, but the events originating from butanol ranged between TOF
>>> paddles 21 through 23. It then follows that the efficiency for a proton
>>> with fixed lab angle and eloss corrected momentum will depend upon the
>>> target of origination.
>>>
>>> The important thing to keep in mind is that the scale factors do not
>>> represent the ratio of butanol bound nucleons to that of carbon. The
>> scale
>>> factors also include the ratio of efficiencies. If the efficiency ratios
>>> were equal to one (no z-vertex dependence on particle efficiency)
>> than we
>>> would not see any structure in the scale factor phase space and the
>> scale
>>> factors would just represent the ratio of bound nucleons between
>>> the butanol and carbon targets.
>>>
>>> Since the scale factors contain the ratio of efficiency between events
>>> that originate in the butanol to those coming from the carbon (not always
>>> = 1), then events that have TOF trigger problems may very well have
>> a
>>> different efficiency ratio than for events without TOF trigger issues.
>>> This means that if the scale factors are measured using the
>> reactions with
>>> pi+ pi- p in the final state, then these scale factors may not be correct
>>> for the single proton or single pion events.
>>>
>>> Thanks for your time.
>>>
>>> I hope this makes sense. If I got something wrong, please let me know.
>>>
>>> Take care,
>>> Michael
>>> _______________________________________________
>>> Frost mailing list
>>> Frost at jlab.org
>>>
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