[esa-t474] 72 hours before paper submission

[Mark Slater]

Just making sure you're all aware!

Thanks,

Mark

On Sun, 9 Mar 2008, Mark Slater wrote:

> Dear All,
> 
> After help from Alex, I believe I've now answered (and corrected) all the 
> points raised by the reviewer. As before, the new version is at:
> 
> www.hep.phy.cam.ac.uk/~slater/esabpm.pdf
> www.hep.phy.cam.ac.uk/~slater/esabpm.ps
> 
> the submitted version can be fonud at:
> 
> www.hep.phy.cam.ac.uk/~slater/esabpm_old.pdf
> www.hep.phy.cam.ac.uk/~slater/esabpm_old.ps
> 
> I plan to submit in TWO WEEKS TIME!! If anyone has any 
> comments/criticisms/complaints, please let me know before then!
> 
> Thanks,
> 
> Mark
> 
> P.S. Comments that I will send to the reviewer are listed below:
> 
> 
> Reviewer #1: I believe this is a valuable, relevant to NIM, and very 
> detailed manuscript. The community will benefit 
> 
> from its publication. I have the
> following comments, all of which should be solvable by simple editing:
> 
> ******************************** 
> 
> 1) The discussion starting with line 441 and ending with line 474 is
>    confusing. I will attempt to summarize my understanding of it: On each
>    shot, eight pieces of data are collected from the outer two BPM's,
>    including the I and Q signals in each direction. The correlations
> between this data and the the I and Q of the central BPM are analyzed over
> many shots, such that eighteen linear parameters are found that best
> predict the central BPM data (nine parameters for I, and nine parameters
> for Q).
> 
> If that is the case, then the authors should explicitly state that x_i and
> x'_i in Equation 16 are derived from the I
> and Q signals of one of the outer BPM's. The phrase "outer BPM
> coordinates" sounds vague, since coordinates could be taken to mean
> positions only.
> 
> 
> MWS:  Reworded these paragraphs
> 
> ********************************
> 2) In several places (line 178 on p. 12, and later, in lines 671 to 674 on 
> p. 42, line 587, p. 35), the paper talks 
> about unwanted coupling with other modes
> in the cavity. BPM 1 is said to have rectangular cavities, and I am 
> guessing that the mechanical damage brought the 
> detuned orthogonal mode closer to the
> filter acceptance window.  Is the artifact in the BPM 4x signal due to the 
> same issue? In that case, analysis of the 
> residual vs. motion in the y-direction
> would give a much clearer indication of the source of the cross-coupling 
> (if data is available).
> 
> MWS:  The artifact seen in 4x (assuming you mean fig. 22a) is just an
> example seen in other BPMs - notably y and 9-11. If it was leaking from 
> the y direction, I would expect it to show an overall worsening of 
> resolution, not a correlation (unless the y movement of the beam was 
> correlated with the x movement, which it didn't seem to be).
> 
> ********************************
> 
> 3) I recommend the description of the SLAC "A-line" (line 82 on p. 6 to 
> line 121 on p. 8) to be better "decoupled" 
> from the discussion of the ESA beamline.
> Initially, I was looking for BPM's 1-9 in the Figure 3 description of the 
> A-line, and only realized the general 
> layout of the beamline components after
> re-reading both sections a couple of times.
> 
> MWS:  Removed most of the ESA references in the A-line section and added 
> another 
> sub-heading
> 
> ********************************
> 
> 4) Table 7: the fourth entry in the table is "Q cavities". I could not 
> find in the text what this refers to. Are 
> these the phase reference cavities?
> 
> MWS:  changed to Ref. Cavities
> 
> ********************************
> 
> 5) Fig 16 is missing the plot legends.
> 
> 
> MWS:  Fixed
> 
> ********************************
> 
> 6) In some of the plots, a label such as "BPM 4x Residual" is easy to 
> mistakenly read it as "four times"  the 
> residual, thus giving the impression that the
> signal was rescaled by a factor of four. A notation such as BPM-4X might 
> make it easier to interpret the plots.
> 
> MWS:  All plot labels fixed
> 
> ********************************
> 
> 7) The definition of "linked" system resolution starting in line 544, p. 
> 32 is a bit vague. Assuming a straight line 
> trajectory through a set of BPM's, the
> residual of each BPM is calculated, which gives up to eight numbers. At 
> this point, I am confused about whether a 
> single BPM is selected and the RMS value of
> its residual is called the "linked" system resolution, or whether a 
> further RMS is performed on all the residuals of 
> up to eight BPM's in the set. In the
> case of a single BPM, how is that BPM selected?
> 
> MWS:  This is incorrect. The residual of a single BPM is calculated from a 
> prediction formed from all but the neighbouring 
> BPMs. Reworded this to make it clearer.
> 
> ********************************
> 
> 8) Table 8 and its discussion would be clearer if: 1) the table column 
> headings were called something like "Measured 
> resolution, x", and "Predicted
> resolution, x", etc. and; 2) The sentence on line 552, p. 33 was changed 
> to alert the reader that predicted 
> resolution is defined in the next paragraph.
> 
> MWS:  Done
> 
> ********************************
> 
> 9) In the discussion of measured system resolution on line 554, p. 33, I 
> wonder if the digitizer was operated near 
> the peak of its range, or would additional
> signal amplification further reduce the digitizer noise?
> 
> MWS:  I have reworded the statement on attenuation optimisation to 
> indicate that this is what we do, i.e. we optimise the signal levels so 
> that we get the best range (~+-1mm) and the best resolution (largest 
> gain).
> 
> ********************************
> 
> 10) Figure 18, I can guess that the black points are the mean, and the red 
> region is the RMS width, but it should be 
> stated explicitly. Also, the meaning of
> the green lines is not at all apparent.
> 
> MWS:  Added to captions
> 
> ********************************
> 
> 11) In general, the paper would benefit from a statement of the BPM 
> sensitivity (signal voltage for a given bunch 
> charge and displacement),  typical signal
> levels seen at various points in the processing electronics, a more 
> detailed description of the electronics 
> components used (mixers, amplifier), and a
> discussion of the likely sources of electronic noise.
> 
> MWS:  Added more specifications on the equipment, added the BPM 
> sensitivity and improved the discussion on dominant noise sources. 
> Unfortunately, we don't have the data available for the signal levels 
> through the electronics chain, but a quick analysis showed that the 
> thermal noise level was significantly below the digitiser noise level and 
> so this was assumed to be domoinant.
> 
> ********************************
> 
> 12) Minor grammatical errors on lines 587, 654, and 656.
> 
> MWS:  Fixed
> 
> ********************************
>