[Frost] Scale factors and dilution factors

[Bill Briscoe]

>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
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> > Frost at jlab.org
> > 
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