Re: [BLAST_ANAWARE] GEp/GMp plot

From: Richard Milner (milner@mitlns.mit.edu)
Date: Wed Mar 31 2004 - 15:44:12 EST


John,
Thanks for the update. I also am impressed with Adrian's work.
Richard

On Wed, 31 Mar 2004, John Calarco wrote:

>
> Richard,
>
> A couple of points:
>
> (1) Thus far the only errors that are included are statistical. The
> systematic errors due to uncertainty in the q-angle and target
> spin angle are not yet included, but Adrian, Tong, and I have
> discussed them (just yesterday afternoon).
>
> (2) The effect of the "dilution factor" should already be included
> because it will determine the error on the asymmetries. If the
> product of beam and target polarization is small, then the
> observed asymmetry will be small and the relative error in the
> asymmetry will be large with the same statistics. In the super
> ratio, which is used to extract GE/GM, the dilution factor itself
> cancels out, but the relative error on the asymmetries in the
> numerator and denominator propogate through.
>
> (3) That said, we do need to thoroughly understand the error analysis
> and add in the systematic errors.
>
> But I think Adrian's analysis shows we are getting closer. The good
> news was that GE/GM came out about right at the lowest Q^2. What we
> don't yet understand is the fairly rapid decrease with increasing Q^2.
>
> John
>
>
>
>
>
> On Wed, 31 Mar 2004, Richard Milner wrote:
>
> >
> > Hi Adrian,
> > Thanks for your message. I am looking forward to your presentation. My
> > point is that you should do a sanity check on the error bars using the
> > known `dilution factor' and total number of ep events and compare with the
> > proposal. The bottom line is to check that your results make sense. This
> > is important for extrapolating to future running.
> > Thanks,
> > Richard
> >
> >
> > On Tue, 30 Mar 2004, Adrian T Sindile wrote:
> >
> > > Hi, Richard!
> > > I do not trust the error calculation at this point (I wrote that code
> > > while on shift on Monday) - and GE/GM drops off much faster than
> > > expected... then goes back up.
> > > I was excited about actually getting to the point of extracting GE/GM, not
> > > because I was confident in the result...
> > >
> > > I know I get the super-ratio versus Q2 correctly (and I trust the error
> > > calculation for that). I am looking into this and hope to be able to say
> > > more on Thursday...
> > >
> > > Adrian
> > >
> > > -------------------------------
> > > Adrian Sindile
> > > Research Assistant
> > > Nuclear Physics Group
> > > University of New Hampshire
> > > phone: (603)862-1691
> > > FAX: (603)862-2998
> > > email: asindile@alberti.unh.edu
> > > http://einstein.unh.edu/~adrian/
> > >
> > >
> >
> >
>
>

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