[Clascomment] OPT-IN:Precise Determination of the Deuteron Spin Structure at Low to Moderate Q2 with CLASand Extraction of the Neutron Contribution

[Daniel Carman]

Dear Nevzat, Sebastian et al.,

I have read through your draft of the deuteron spin structure paper and it really is
quite impressive. Your manuscript represents a significant amount of work. Here I
provide my comments after reading the draft dated Apr. 12, 2015. As I am certainly
not an expert on this physics, I cannot say that I understood all of the discussion,
but I pass on what I noted in my reading. if you have any questions, let me know.


					        Regards,
						
						Daniel

************************************************************************************
General.
 - For the most part you use the terms "statistical uncertainties" and "systematic uncertainties"
   in this paper. Several times you change to the word "errors". I do not find this term
   appropriate and suggest that you stick with "uncertainties" throughout. I tried to catch these
   in my comments below, but may have missed a couple of them.

Page 1.
 - Abstract. Line 7. Use "... from these data the polarized ...".
 - Line 19. Use "... observables, the inclusive spin ...".

Page 2.
 - Eq. 6. What convention dictates the sign of the asymmetry? Should there be a reference
   here to the literature on this choice?
 - Line 129. Use "... of the longitudinal to transverse ... cross sections, ..."
 - Eq. 7. What is gamma^*?

Page 3.
 - Line 136. The statement here is not clear to an outsider like me. "Given a model or
   other information ... A1 can be extracted directly from Eq. 10 ...". What is special about
   A1? You could have extracted any of the other quantities give a model of the others.
 - Eq. 12. Add a comma after this equation.
 - Line 156. Use "... the unpolarized up and down ...".
 - Line 203. Here you mention "EG1 data". What is EG1? You have made clear what EG1b is, but
   is EG1 a different experiment?

Page 4.
 - Line 252. Use "... lower $Q^2$ than the present data, ...".
 - Line 301. Use "... a reduction factor $(1 - 1.5 P_D)$ to ...".

Page 5.
 - Section IVA. Should you not mention the trigger configuration here (or somewhere). How
   many triggers were recorded for each beam energy/torus setting?

Page 6.
 - Line 472. Add a period at the end of the sentence.

Page 7.
 - Line 499. Use "... directly from the radiated ...".
 - Line 520. Use "... the inner DC layer.".

Page 9.
 - Eq. 26. Add a comma after this equation.

Page 10.
 - Line 704. Use "... in these sources were properly ...".
 - Line 743. Broken reference.

Page 11.
 - I question in Figs. 7, 8, 9 if the different uncertainty bands shown for the individual sources
   are value added. I think they just clutter up the figures and you only need to include the green
   (total uncertainty) band.
 - Line 772. Missing units on W.

Page 12.
 - Fig. 9 caption. Line 2. Use "... deuteron versus $W$ for a ...".
 - Line 790. Another experiment, EG1-dvcs, introduced without explanation.
 - Line 791. Use the degree symbol instead of spelling out the word. Same in line 793.

Page 14.
 - Fig. 13 caption. Line 3. Use "... as the red line on ...".
 - Line 900. Use "... SLAC, HERA, CERN and Jefferson Lab ...".

Page 15.
 - Line 932. Use "statistical uncertainties".

Page 16. 
 - In Fig. 15 (and Fig. 20), the open blue circles from the EG1b data at higher Q2 do not
   match the other (extrapolated) data. This does not seem to be discussed in the text. Why
   are the open blue circles off the trends at high Q2?
 - Line 936. Missing units on W.
 - Footnote 2. Missing units on W.

Page 17.
 - Line 1018. Remove the space after $\gamma_0$ (before the comma).

Page 18.
 - Fig. 18 caption. Use "Color Online".
 - Fig. 18 caption. Line 3. Use "... Ref. [26] versus the ...".
 - Fig. 19 caption. Line 6. Missing period at the end of the sentence.
 - Line 1065. Use "uncertainties".

Page 19.
 - Fig. 20 caption. Use "Color Online".
 - Fig. 20 caption. Last line. Spurious extra period at the end of the sentence.
 - Fig. 21 caption. Use "Color Online".

Page 20.
 - Line 1131. Broken reference.
 - Line 1137. Spurious extra period at the end of the sentence.
 - Line 1149. Use units with c=1 as you have everywhere else in this paper.

References:
 - Put the references in the order cited in the paper.
 - Do not include the pre-print numbers for papers that have already been published.
 - Most of the references have formatting problems with no spaces between the words in the
   journal name, e.g. Phys.Rev.Lett. instead of Phys. Rev. Lett.
 - Ref. [54] has the journal name without abbreviations and all in capital letters.
 - Ref. [57] is incomplete as written.
 - Ref. [62] is not a CLAS Collaboration paper. First author should be "B.A. Mecking".