[Clascomment] comments on The Beam-Target E asymmetry for vec gamma vec n -> pi- p in the Nâ resonance region

[Dr. A.M. Sandorfi]

Hi Barry,
Thanks for your comments. Please see embedded responses below.
Andy


On 3/15/17, 2:38 PM, "Barry Ritchie" <Barry.Ritchie at asu.edu> wrote:

> Great to see this coming out. I have the following comments after a quick
> read-through:
> 
> 0. Since Patrick Collins was also supported by ASU during 2016, perhaps
> Arizona State University, Tempe AZ 85287-1504 should be added to his address
> superscript. 
________________
Patrick began his involvement with this experiment only in 2011, while a
Catholic U postdoc.
________________


> 
> 1. Only the first word of the title should be capitalized: "The beam-target
> asymmetry $E$..."
________________
Well, the Ad Hoc committee suggested capitalizing each major word of the
title. I scanned recent PRL articles and they in fact are titled in this
way.
________________


> 
> 2. In the second line of the abstract, W should be italicized.
________________
Done
________________


> 
> 3. On page 2, please cite the tagger NIM article: D. I. Sober et al. Nucl.
> Instrum. Meth. Phys. Res. A 440, 263-284 (2000).
________________
Done
________________


> 
> 4. On page 3, please add "with |P_{miss}| \leq 0.1 GeV/c" to the caption of
> Fig. 2. You should also indicate what uncertainty is represented by the error
> bar in that figure.
________________
You misunderstand the figure. This is a plot of the mean value of E,
averaged over all angles and energies, binned as a function of |Pmiss|. Each
point results from a separate analysis with a different value for |Pmiss|.
The error bars are statistical and increase at higher |Pmiss| since the
momentum distribution peaks around 0.06 GeV/c.

I've added the following sentence to the caption that I hope helps to
clarify the plot:
"  The uncertainties are statistical and are smallest near the peak of the
$|p_{miss}|$ distribution ($\sim$0.06 GeV/c).  "
________________


> 
> 5. On page 3, second paragraph, there is an extra "the" that should be removed
> : "reproduces the observed the..."
________________
Done
________________


> 
> 6. Why is the photon beam polarization uncertainty so large (given as 3.4%)?
> With Ref. 12, most of this uncertainty likely comes from the Moeller
> measurement, right? Then that photon beam polarization uncertain seems quite
> high for a Moeller measurement uncertainty for any reasonable period of time.
> Is that a typo?
________________
The statistical error on the Moller data was between 1.4 and 1.4%. A larger
uncertainty comes from the std dev of repeated measurements, which was about
\pm 0.04, and this corresponds to 3.3 - 3.4% for 82 - 88% electron
polarization. We suspect this variation comes from non-uniformities in the
magnetized scattering foil.
________________


> 
> 7. On page 4, I would suggest substituting "very discordant" perhaps for the
> words "wildly disparate". At any rate, "disparate" is not really the word you
> want here. 
________________
Well, you know at some point such adjectives are a matter of taste.
"Discordant" is too musical for me. "Disparate" is "essentially different in
kind", which I think is not a bad description for curves that look
completely out of phase.
________________


> 
> ---BGR
> 
> 
>