[Clascomment] OPT-IN:Measurement of the free neutron structure function using spectator tagging in inelastic d(e, e' p_s)X scattering with CLAS

[Daniel Carman]

					December 10, 2013


Dear Slava et al.,

I have read through your paper free neutron structure function with the BONUS
detector dated December 4, 2013. This paper was quite well laid out and quite
well written. I do not have too many comments on the physics, which was clearly
presented. What comments I do have are included below. If you have any questions, 
let me know.


    			         Regards,

				         Daniel

********************************************************************
General:
 1). In general my preference is to use the word "uncertainty" instead of "error". An
     error implies that you have made a mistake of some sort. I would be in favor of
     removing all traces of the "error" language with "uncertainty" throughout the paper.

 2). You have taken pains to include proper speed of light units on W, Q2, and mass. However,
     you have not been consistent with your usage throughout the paper when it comes to
     writing your formulas. You should check things over, but I found consistency issues at:
     - Line 252.
     - Line 282.
     - Line 363.
     - Eq.(10a).
     - Eq.(11).
     - Line 1238.
     - Line 1496.

3). You are not consistent with your notation for the deuteron. Sometimes you use "d", sometimes
    "D", and sometimes "2H". Pick one and be consistent throughout the paper.

Page 1.
 - After author list. Use "CLAS Collaboration".

Page 3.
 - What is the unexplained arrow drawn on Fig. 1?

Page 4.
 - Line 3 before Eq.(4a). Use "Eq.(3)"
 - Line 274. Use "... the bound neutron structure functions ...".

Page 5.
 - Line 295. Use "Eqs.(5)".
 - Line 296. Use "semi-inclusive structure functions can ...".
 - Line 314. Use "Eqs.(5)".
 - Line 385. I suggest "... are small as expected, and ...".

Page 6.
 - Line 423. "polarization up to 86%" makes it sound like this is some limit of the
   accelerator. It is not of course.
 - Line 466. Use "These detectors were complemented by ...".
 - Line 492. Use "... kind of detector, made it a ...".

Page 8. 
 - Line 611. Use "See Ref. [48] for a ...".
 - Line 620. What do you mean by "known imperfections"? Be explicit here. This seems obtuse.

Page 9.
 - Eq.(8). Why is this form not also a function of the solenoid field?
 - Line 672. I suggest "the number of ionization electrons ...".

Page 10.
 - Line 737. Formulae should be in math mode.
 - Section 3. You do not mention how well the beam energy is known.
 - Line 753. Use "uncertainty of the proton missing-mass ...".

Page 11.
 - Lines 776-779. I have no idea what you are trying to say here. Please rewrite.
 - Line 815. Use "were accumulated".

Page 12.
 - Line 895. Use "Monte-Carlo based analysis".
 - Line 911. Use "Event generator".

Page 13.
 - Line 1005. I suggest "... smearing to the data to match the true detector resolutions.".

Page 15.
 - Line 1129. Use "... other backgrounds ...".

Page 16.
 - Table I is not referenced in the text.
 - Need a period at the end of Eq.(16).

Page 17.
 - Line 1307. Use "... contaminations of tagged ...".
 - Line 1318. Use "... in Table II), ...".

Page 21.
 - Line 1474. Here you say that in Fig. 14 you "note a more pronounced" fall-off vs. W*
   for sideways angles compared to backward angles in Fig. 13. This does not agree with
   the data in these figures. For the highest ps bin, the change in the ratio from low W*
   to high W* is the same, about 0.3.
 - Line 1500. Use "... as a function of $x^*$ ...".

Page 22.
 - Fig. 17 caption. Next to last line. Use "... as a solid line".
 - Line 1544. "they are available in tabular form in the supplemental material of this
   publication". This statement is obtuse with include an explicit reference to the CLAS
   physics db.
 - Line 1557. Use "... shown as a solid line.".

Page 23.
 - Fig. 19 caption. Next to last line. Use "... shown as the solid band.".

Page 24.
 - Fig. 20 caption. Sixth line. Use "... as the (red) shaded band ...".