[Clascomment] OPT-IN:Alignment of the CLAS12 central hybrid tracker with a Kalman Filter

[Daniel Carman]

Dear Sebouh et al.,

I have read through the draft of your paper on the CVT alignment algorithm and include my comments
below. Most of my comments deal with grammar/style, but I have a few comments regarding presentation
as well. Good luck with your path to publication.

If you have any questions, let me know.

Regards,
Daniel
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General:
 - You are not consistent with your usage of "beam line" and "beamline". I prefer the latter usage.
 - You are not consistent with your usage of commas in lists. You can use either  "A, B and C" or
   "A, B, and C", but you go back and forth randomly. Please choose one style and stay with it
   throughout. By the way, I prefer the latter format (referred to as "English" commas).
 - You often have a separation of values and their units across lines. To keep them together using
   latex use, e.g. "5~T" or "50~$\mu$m".
 - You switch back and forth from describing your work in present verb tense and past verb tense. You
   should consistently use past tense. I will include some suggestions in my comments below.
- After reading the paper I note that you have not made clear that you assume the detector "modules"
  are all rigid bodies. This should be explicitly stated early on that you have assume that there are
  no geometric distortions (e.g. warps, twists, bends) in the detector subunits.

Page 1:
 - Author name are not listed consistently. Sometimes you use the first name and sometimes the
   first initial.
 - Address 2: No need to include "(Jefferson Lab)" in the address. Also use "USA" instead of
   "United States".
 - Address 4: Use "IRFU".
 - Abstract. Line 14. Use "... located within a 5~T superconducting solenoid.".
 - Abstract. Line 19. Use "... of the CLAS12 CVT ...".
 - Abstract. Line 21. Use "... of the residual spectra were greatly ...".
 - Line 33. Use "... [6-8] in Hall~B at Jefferson Lab".
 - Line 35. Use "... detector data and a model of the ...".
 - Line 38. Use "... between the measurements along ...".
 - Line 42. Use "... the residuals ({\it i.e.} the track fit $\chi^2$).".
 - Line 58. Use "... both of these problems.".

Page 2:
 - Line 81. Use "azimuthally curved". (No hyphen with words ending in -ly.
 - Line 102. Here you are not consistent with writing "Section" or using the abbreviation "Sec.".
   Be consistent throughout the manuscript.
 - Line 109. Use "Central Vertex Tracker".
 - Footnote 3. End the sentence with a period.
 - Table I caption. Line 4 Use "... backing structure and the beamline.".

Page 3:
 - Fig. 2 caption. Line 4. Use "Bottom (from Ref. [7]):".
 - Line 150. Use "We use the Kalman Alignment Algorithm (KAA), ...".
 - Line 151. Use "... in detail in Refs. [3,4].".
 - Line 156. End the sentence with a period.
 - Line 158. Use "... of measurements and produces ...".
 - Line 178. Use "These matrices, which are summarized below, model the ... on these residuals.".
 - Footnote 4 . End the sentence with a period.

Page 4:
 - Line 199. Use "We represented ...".
 - Line 204. Use "We defined ...".
 - Line 209. Spurious extra period and space before footnote 6. Use "We also defined ...".
 - Line 214. Use "... analogously constructed ...".
 - Line 216. Use "We then extrapolated ...".
 - Line 221. Use "... we chose the ...".
 - Line 226. Use "... we then determined ...".
 - Line 234. Use "We calculated ...".
 - Footnote 6. End the sentence with a period.
 - Eq. 7. Add a comma at the end.
 - Line 264. Use "We used the ...".
 - Eq. 10. Add a comma at the end.
 - Line 265. Do not indent this line.
 - Line 266. Use "... measurement in the track and $x_j$ is ...".

Page 5:
 - Fig. 3 caption:
   - Line 2. Use "... and red, respectively.".
   - Line 4. Use "... BMTC, we used the tangent point).".
 - Line 272. Do not indent this line.
 - Line 273. Use "... in the track and $t_j$ is ...".
 - Line 279. Do not indent this line. Use "... and $\vec{R}$ vectors represent ...".
 - Line 298. Use "... and BMTC, respectively".
 - Add a comma after Eq. (19) and after Eq. (21). Remove the comma after Eq. (20).
 - Line 304. Use "... dimensions as {\bf D}. The matrix {\bf V_D} can be interpreted as the sum ...". (i.e. drop
   the sentence "The meaning of the matrices ... as follows.".
 - Line 307. Use "... due to the alignment ...".
 - Line 308. Use "... be interpreted as a projection ...".
 - Line 314. Use "non-linearity".
 - Line 320. Do not indent this line.

Pages 6,7,8:
 - Figs. 4,5,6 captions. Use "... left column), rotation ... three panels), and variation in ...".

Page 9:
 - Line 329. Problem with closing parenthesis on "cosmic run".
 - Line 337. Use "... straight lines, which have ...".
 - Line 356. Use "... near 0$^\circ$ and 180$^\circ$) and ...".
 - Line 377. Use "... multiple times, we developed a procedure to create ...".
 - Line 380. Do not indent this line. Use "First, we ran a ...".
 - Line 385. Use "... events that die not have tracks ...".
 - Line 395. Use "... all tracks had at least ...".
 - Line 396. Use "... two BMTZ clusters, and two pairs ...".
 - Line 403. Use "... procedure was comprised of several ...".
 - Line 411. Use "... a set of track measurements, along with the alignment ...".
 - Line 415. End this sentence with a period.
 - Line 417. Use "... we ignored the effects ... which were used ...".
 - Line 418. Use "We did this in ...".

Page 10:
 - Fig. 7. The axis value font size is too small. Missing x and y axis labels on the plots.
 - Line 423. Use "Several cycles were necessary ...".
 - Line 430. Use "Therefore, the alignment ...".
 - Line 433. Use "We used an event ...".
 - Line 439. Use "All three subsystems were fit ...".
 - Line 443. Use "... each iteration, the diagonal ...".
 - Line 449. Use "... all BMTZ sensors and rotations in ...".
 - Line 457. Use "... we used the following values:".
 - Line 464. Use "... the initial uncertainties has ...".
 - Footnote 9:
   - Lines 3,5. Wrong units are given as mm and should be $\mu$m.
   - Line 3. There is a label to a superscript "10" that does not exist. Something is problematic here.

Page 11:
 - Line 470. Use "We assumed that ...".
 - Line 473. Use "... and had the same ...".
 - Line 475. Use "Therefore, we introduced ...".
 - Line 504. For previous bulleted list in lines 480 to 500, you ended each item with a period. In the
   bullet items in lines 504 to 509, you do not do the same.
 - Line 511. Use "... above, were set to zero.".
 - Line 513. Use "... BMT sensors, there are ...".
 - Line 530. Use "... BMTZ (b), and ...".
 - Line 538. Use "... 57~$\mu$m, 230~$\mu$m, and ... BMTC, respectively.".
 - Line 540. Typo on "spatial".
 - Line 541. Use "... [7] and [8], respectively.".
 - Line 544. Use "... consistent with the system design goal of ...".
 - Line 545. Use "... 5\% for charged particles with ...".
 - Line 550. Here you introduce the term "number of degrees of freedom". You should give your abbreviation here.
   Note that you use "dof" in the text, but "ndof" for the plot labels in Fig. 8.
 - Line 556. Use "There is a very small ...".
 - Footnote 12. End this line with a period.

Page 12:
 - Fig. 8. Starting here and for all remaining plots, you have the "preliminary" stamp across the plot. This must
   be removed.
 - Fig. 8 caption. Line 2. I suggest "Each hit cluster produces a single residual in the track fit.".
 - Line 565. Use "Therefore, we determined ...".
 - Line 568. Use "... of them had large ...".
 - Line 572. Use "(460) $\mu$m for ...".

Page 13:
 - Line 578. Use "... we studied the dependence ...".
 - Line 579. Use "Figure 11 shows ...".
 - Line 585. Use "The KAA algorithm also ...".
 - Line 591. Use "... for any of the BMTC sensors are ...".
 - Line 604. Use "... in $z$, which is a weak ...".
 - Line 637. Use "... after alignment.".
 - Line 652. Use "... field turned on). Using a run configuration ...".
 - Line 653. Use "5~nA".
 - Line 655. Use "These were selected ...".
 - Line 659. Use "... which was assumed ...".
 - Footnote 13. Add a comma before "where $Q^2$ is ...".

Page 14:
 - Fig. 10 caption. Line 3. Use "... the upper error bar ...".
 - Line 666. Use "... beam energy, as a curve overlaid ...".
 - Line 667. Use "vs.".

Page 15:
 - Fig. 11 caption:
   - Line 1. Use "... alignment, as a function of the kinematic ...".
   - Line 3. Use "... upper error bar to the ...".

Pages 16,17:
 - I really do not think Figs. 12, 13 belong in this paper. They are nearly impossible to interpret in their
   present format. However, the information they contain is valuable. There has to be a better way to display
   this information in a better manner. Have other papers found a more appropriate/viewable way to display this
   type of information?
 - Fig. 13 caption. Line 3. The closing parenthesis on "streaks" does not match the opening parenthesis.

Page 19:
 - Line 678. Use "10~$\mu$m".
 - Line 684. Use "By adapting the algorithm to the CLAS12 CVT, we demonstrated the flexibility ...". (i.e. do not
   repeat the information just given in lines 673-675).
 - Line 687. Use "Kalman Alignment Algorithm".
 - Line 692. Use "... of the CLAS12 CVT".
 - Check the NIM reference style requirements. Your format is not standard.
 - Refs. Use "{\it et al.}".
 - Ref. [6]. Use "V.D. Burkert {\it et al.} {\it (CLAS Collaboration)}, ...",

Page 20:
 - Line 778. Use "... and 16, respectively.".
 - Line 779. Use "We show residuals versus the measured centroid ...".
 - Line 781. Use "... in the top (bottom) row.".
 - Line 783. Use "(see Fig. 15)".
 - Line 798. Use "... strong correlations for some ...".
 - Line 802. Use "(see first row of Fig. 18).".
 - Line 805. Use "(see third row of Fig. 19)".
 - Line 821. Use "... and to initialize the ...".
 - Line 824. Use "... and to initialize the ...".
 - Line 848. This is an orphan sentence. I think it should be merged with the previous paragraph.
 - Line 852. Use "... simulations as a function of the kinematics ...".
 - Line 857. Use "cosmics".
 - Line 864. Use "... for such clusters.".

Page 24:
 - Fig. 18 caption. Line 4. Use "... the same sector module, two SVT ...".

Page 25:
 - Fig. 19 caption. Line 2. Use "... layers, two BMTZ sensors in ...".

Page 28:
 - Fig. 22 caption:
   - Line 5. Use "... outside of the range of the plot.".