OPT-IN: Photoproduction of η mesons off the proton for 1.2 < Eγ < 4.7 GeV using CLAS at Jefferson Laboratory

[Daniel Carman]

Dear FSU folks,

I have read through the draft of your paper on eta photoproduction and include my comments below.
Most of my comments deal with grammar/style, but I have one comment regarding presentation. The
results are quite nice and your presentation of the results is very nice.

If you have any questions, let me know.

Regards,
Daniel
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General:
 - You are not consistent throughout with usage of "CB-ELSA" and "CBELSA". I prefer the former.
 - You usage of hyphens throughout is generally O.K., but there is a quirk in the rules. You should not
   use a hyphen if the first word ends in "ly".
 - I prefer that there should be no space between a "%" symbol and its value. e.g. Use "58\%".
 - Throughout, use "liquid-hydrogen target".
 - You are not consistent through with handling speed of light units c. I suggest you choose a presentation
   format with c=1.
 - I prefer the usage "livetime" and "deadtime". Sometimes you leave a space, sometimes you use a hyphen.

Presentation:
 - The ordering of your figures is really quite distracting. It affects the flow of the paper and its readability.
    I recommend that Figs. 12 and 14 be moved so that they are not in the middle of the cross section results.
    They are referenced out of order in the current layout.

Page 1:
 - Line 48. Use "photo-induced".
 - Line 59. Use "... state, which itself ...".

Page 2:
 - Fig. 1 is B&W, no need for "(Color online)".
 - Line 3. Use "... nuclei, as well as ...".
 - Line 28. Use "... physics, as well as ...".
 - Line 34. Use "... either tagged-photon beams ...".
 - Line 43. Use "tagged-photon".
 - Line 45. Use "... table of the ...".
 - Line 65. Use "... quantameter that was ...". By the way, this is the first time I have ever stumbled across
   this term.

Page 3:
 - Line 4. Use "time-of-flight".
 - Line 26. use "data taking".
 - Line 28. Use "... tagged-photon energies ...".
 - Table I. Simplify the first column. List the reactions only once in the top part and bottom part of the figure.
 - Line 41. Use "multi-photon".
 - Line 44. Use "... hemispheres that covered ...".
 - Line 84. Use "... from a 60 -- 65~nA electron ...".
 - Line 87. Use "... experiment, which was a ...".

Page 4:
 - Fig. 2 caption. Use "... including the photon tagging facility upstream of CLAS.".
 - Line 3. Use "... GeV, corresponding to about ...".
 - Line 18. Use "... setup that differ ...".
 - Line 33. I suggest "... scintillation counters close to the target (referred to as the start counter) provided ...".
 - Line 36. Use "... time-of-flight system ...".
 - Line 39. I suggest "... of charged tracks in CLAS (see Section IV E for details)."
 - Line 43. Use "... electrons, which ...".
 - Line 45. Use "... hodoscope that contained ...".
 - Line 54. Use "... of the E-counters ...".

Page 5:
 - Line 8. Use "In particular, ...".
 - Line 12. Use "This resolution effect, combined ...".
 - Line 20. Use "... from the drift chamber and TOF systems."
 - Line 21. Use "... defined as the ratio of the particle speed ...".
 - Line 41. Use "... time differences were used ...".
 - Fig. 3 caption. Use "... further analysis only if a single photon ...".
 - Fig. 3. You have introduced 3 different times, t_{track}, t_{TGPB}, and t_{coincidence}. These terms
   are not all defined and add confusion. Please review.
 - Line 67. Use "... distributions (coordinate along the beamline) for data ...".
 - Line 71. Use "... pressure were sampled continuously throughout each run.".
 - Line 76. Use "... of the various ...".

Page 6:
 - Line 56. Use "... \Sigma^+}$, which will ...".
 - Line 61. Use "... \pi^0$, followed by ...".
 - Line 64. Use "269,308" (it looks like you have a space after the comma).
 - Line 65. Use "... incident photon ...".

Page 7:
 - Fig. 5. What is the relevant momentum range for pions and protons in your data? Is this consistent with
   the momentum range shown in the right-most plot?
 - Eq. 1. Use "\left \vert ... \right \vert" about your terms to make properly sized absolute value signs.
 - Line 18. Use "... outside of the active ...".
 - Line 24. Use "... solid angle for small polar angles.".
 - Line 27. "Due to the hyperbolic geometry ..." Huh? I have no idea what you are trying to say here.
 - Line 36. Use "$z$-vertex".
 - Line 48. "... would create an artificial $\pi^0$ in the final state that would move along the incident photon-beam
    direction." This is a really awkward statement and I am not a fan. This channel simply creates a background in
    your mass spectra. It does not "create" anything. Please revisit this sentence.
 - Line 53. Use "... background, only events ...".
 - Line 66. I recommend that you start a new paragraph with this sentence "Figure 6 (center) ...".
 - Line 74. Use "confidence-level".

Page 8:
 - Line 5. Here you introduce the variable p. It is not necessary. Why not just use "CL"?
 - Line 21. Use "... bin was then ...".
 - Eq after line 23. Need a period at the end of the equation.
 - Line 29. Use "... sector of CLAS.".
 - Line 31. Use "... see Section III E), ...".
 - Line 34. Use "... of events where a third ...".
 - Line 51. Use "... determined that describes ...".
 - Line 56. Use "... was fit according ...".
 - Line 61. Use "Chebyshev".

Page 9:
 - Eq. 5. Add a comma at end of equation.
 - Line 12. I suggest that you begin a new paragraph at "Initially defined ...".
 - Line 23. Use "... listed in Eq. 4, ...".
 - Line 25. Use "... denotes the set of ...".
 - Line 26. Use "... events $i$ and $j$, ...".
 - Lines 40,46. You have a semi-colon between your W values instead of a comma.
 - Line 47. Use "An excellent signal / background separation is observed.".

Page 10:
 - Figs. 8, 9 captions. Again you have a semi-colon in your W range.
 - Line 25. Use "... radiator to determine the tagging ...".
 - Line 42. Use "... effective number events in each ...".

Page 11:
 - Line 2. Use "... normalization, as well as ...".
 - Line 15. Use "... distribution that is formed ...".
 - Table II. Use "$z$-vertex cut".
 - Line 39. Use "... uncertainty that is ...".
 - Line 46. Use "... results, which is mostly ...".
 - Line 48. Typo on "hydrogen".
 - Line 48. I suggest "... hydrogen target (density and length uncertainties) ...".
 - Line 67. Use "... as the black data ...".
 - Line 69. Use "... as the read points.".
 - Line 73. Use "... as the blue points ...".
 - Line 77. Use "... as the green points.".

Page 12:
 - Fig. 10 caption. Second line. Use "... shown as the black solid ...".
 - Line 48. Use "...3.12] GeV, and only shows ...".
 - Line 59. Use "... in the form of a normalized ...".

Page 13:
 - Fig. 11 caption. Second line. Use "... shown as the black solid ..." and there is a spurious "8" between
   "associated" and "with".
 - Line 10. Use "... included beyond those listed ...".
 - Line 14. Use "... two data sets.".
 - Line 22. Use "... downstream of CLAS."

Page 14:
 - Fig. 13 caption. Second line. Use "... shown as the black solid ..." and there is a spurious "8" between
   "associated" and "with".
 - Line 19. Use "... models that aim at ...".

Page 15:
 - Fig. 15 caption. Second line. Use "... shown as the black solid ...".
 - Line 19. Missing units on momentum transfer t.

Page 16:
 - Fig. 16 caption. Second line. Use "... shown as the black solid ...".
 - Line 27. Use "... wave that is associated ...".

Page 17:
 - Fig. 17 caption. Second line. Missing units on momentum transfer t. Use "... shown as the black solid ...".
 - Fig. 18 caption. Second line. Missing units on momentum transfer t. Last line. Use "... see the caption ...".
 - Line 14. Use "... as a purple curve; more details ...".
 - Line 15. Use "... in Ref. [76]."

Page 18:
 - Fig. 19 caption. Second line. Missing units on momentum transfer t. Also, no need for "(Color online)" for a
   B&W figure.
 - Line 30. Use "... exchange that would ...".
 - Line 48. Use "... terms of the dominant ...".

Page 19:
 - Line 5. Use "... with the beam-asymmetry results recently ...".

References:
 - Put references in the order in which they are cited in the paper.
 - [2] The Mecking paper on CLAS in not a "CLAS Collaboration" paper.
 - [55]. Do not say "unpublished". Like the other CLAS-Notes, give the URL.
 - [77]. Is not cited in the paper.