[d2n-analysis-talk] z_react Check Via Focal Plane Cuts [Positive Polarity]

[Brad Sawatzky]

On Thu, 06 May 2010, David Flay wrote:

> Attached are the same plots I sent along last time concerning the focal
> plane cuts and their subsequent effect on z_react.  This time, for
> positive polarity run 20620 (p = 1.27 GeV, E = 5.89 GeV, rastered beam 2 x
> 2.6)
> 
> Looking at this plot, the positions of the foils (plot 1) line up with the
> nominal positions, just like negative polarity.

Looks good.

> The focal plane cuts reveal a behavior similar to that of the negative
> polarity plot I showed a few days ago.

An interesting effect, but I doubt our physics will be sensitive to it.

> Concerning a check of rastered beam [optics] runs compared to unrastered
> beam runs, the unrastered runs are few and far between and have very low
> statistics, such that even chaining them together doesn't allow me to make
> a good estimation of the carbon foil widths (using a Gaussian fit).

The HRS optics are quite stable.  It would be useful to compare the
z-react resolutions you're getting with our rastered runs (using our
raster correction) to unrastered runs from Transversity, or even an
older experiment.

> Speaking of widths, you'll also see that the positive polarity widths are
> slightly smaller (~3mm) compared to that of the negative polarity widths
> (~5mm) [for the three main peaks -- both values I obtained from a quick
> Gaussian fit, seen in the plots -- compare the first two plots].  I think

Probably just uncertainty in the fit, as you say.

-- Brad

-- 
Brad Sawatzky, PhD <brads at jlab.org>  -<>-  Jefferson Lab / Hall C / C111
Ph: 757-269-5947  -<>-  Fax: 757-269-5235  -<>- Pager: brads-page at jlab.org
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