[Clascomment] OPT-IN:First measurement of the helicity asymmetry E in eta photoproduction on the proton

[Daniel Carman]

Igor et al.,

I have read through the draft of your FROST eta production E asymmetry paper. This is
a very nice piece of work that I have been looking forward to for some time. Included 
below are my comments on the draft dated May 6. Let me know if you have any questions.


					        Regards,
						
						Daniel

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Page 1:
 - Abstract.
   - Line 3. Use "... using the CLAS detector in Hall B at Jefferson Lab.".
   - Line 4. You state explicitly the W range but curiously do not mention the full
        coverage in the CM angle of the meson. You should make this clear here.
   - Line 5. Use "... of a narrow $N^*$ resonance between ...".
 - Line 9. This sentence reads quite awkwardly. I suggest "Due to the broad widths
   of the nucleon excitations (of the order of 100-300~MeV), the states overlap in
   the mass spectrum. Thus disentangling the individual states to identify their
   exact masses and quantum numbers has been quite difficult.".
 - Eq.(1). Add a comma after the equation for proper punctuation.
 - Line 24. Remove the comma after "polarization".
 - Line 58. Use "... material that produced a ...".
 - Line 69. Use "... field. The principal subsystems of CLAS required ...".

Page 2:
 - Eq.(2). I recommend that you include a reference for your choice of sign.
 - Eq.(3). Add a comma after the equation for proper punctuation.
 - Line 81. Use "... with the Hall~B M{\o}ller polarimeter. The target polarization was
   determined using ...".
 - Line 85. Use "Individual charged tracks ...".
 - Line 94. Use "Charged tracks that could not ...".
 - Line 98. Use "... that the measured $\beta$ be within $\pm$0.04 ...".
 - Line 114. Use "... $\pi^-$ from the $\eta$ decay detected.".
 - Line 116 (and below). Choose units with c=1 throughout.
 - Line 117. Use "Events with both a $\pi^+$ and ...".
 - Line 119. What does the pi0 have to do with anything? I am confused as there are no
   pi0's in your final state.
 - Line 123. Use "... production $\eta$ polar angle ...".
 - Line 137. Use "Since the detector ...".
 - Line 142. Use "... up to fifth order ...".
 - Line 164. Use "... values were derived from ...".

Page 3:
 - Fig. 1. Identify the green and red data points in the left plot.
 - Line 171. Use "... include the target polarization ...".
 - Line 179. Use "... in all analyzed bins;".
 - Line 187. I suggest to begin a new paragraph with the sentence "Missing mass energy
   resolution ...". Although you should use "Missing mass resolution ...".
 - Line 194. Use "... consistency with the detector resolution.".
 - Line 209. Use "... with the $N(1720)$ ...".
 - Line 210. Use ''... slowly varying ...".
 - Line 217. "... motivate additional experimental investigations looking at other spin
    observables.". But FROST is already planning to release other spin observables for
    the eta final state. I should think you would want to explicitly mention that here.

Page 4:
 - Fig. 2 caption. Use "Several phenomenological fits are shown, with all but the one
   represented by the solid line made prior to this data.".

References:
 - Do not list preprint numbers for already published works.
 - Many of the listings do not have proper spacing, e.g. "Phys.Rev.Lett." instead of "Phys. Rev. Lett.".
 - Do not list the URL for Ref.[9].
 - Ref. [10] is not a CLAS Collaboration paper. First author should be listed as "B.A. Mecking".
 - Ref. [16] should have authors "M.D. Mestayer, D.S. Carman, ...".
 - Ref. [21] should be "private communication".
 - Ref. [25], what is the status? Is this published?