Chris Parkes

Major Comments•Comments received from:

Rob Appleby, Chris Thomas, Hans Jurgen-Hilke, Silvia Borghi, Eddy Jans, David Hutchcroft, Lars Eklund, Paula Collins

All minor comments will be considered,

not discussed here

General -1 • all instances of n and p have to be italicised on line 59 to be consistent with the others

(CT)• Why is n+-on-n in italics while p+-type not? (DH)

• spacing between number and units: X\,m where X is number and m the unit looks better.• \sim also should be \sim\,123 (DH)

• Author list consistency (EJ). Discuss at end of meeting – pass to Lars

• Some expressions print wrong at Nikhef, while looking good on the screen.

Strange. For example lines 720, expression (1) between lines 1143 and

1144, expression (4) between line 1256 and 1257. Can be a local Nikhef problem, but might also be caused by the way the pdf is created. Keep in mind. (EJ)

Line 1187: Decide if using radians or degrees for phi as both are used (sticking to one makes reading the paper simpler). (DH)

References - General: not all of them have clickable links. Most of them are available online so we should add these. (LE)

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General -2• some inconsistency in referring to Sections. Sometimes Sect. and sometimes Section. I

think the former should be used unless it is at the start of a sentence then the latter should be used. See e.g. L79-84 for an example of a violation of this rule. (LE)

• The way to refer to sub-figures doesn't always follow the LHCb standard. The descriptor, e.g. (left), should go be lower case, be in parethesis and go before the item it describes. (LE)

• Inspired by the discussion we had for the TDR: do we use the word 'chip' or 'ASIC'? We should be consistent and I prefer the latter which was also the choice for the TDR. (LE)

• Sometimes when a figure with sub-figures are referred to in the text, it refers to the figure (e.g. Fig. 13, on L673) and sometimes it refers to the sub-figure (e.g. Fig 13 (left), on L666). We should probably be consistent with that. (LE)

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Abstract• Should we also quote the typical decay time resolution of 50 fs in the abstract? (LE)

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Section 1 - Intro• Line 7: perhaps include the z range covered by sensors, also a note on coordinate system

used (i.e. z=beam axis, r=radius in cylindrical polars, phi is the azimuthal angle from the horizontal x axis). Later all this is assumed. (DH)

• L15-19: I got some fresh plots from Rafael showing the track reconstruction efficiency vs. eta, that I attached to the email. We could either use those to give some more precise numbers on the eta coverage and also how we define it. E.g. say that the efficiency is larger than 90% between eta something and something. This is somewhat complicated by the fact that the efficiency barely reaches 90% backwards. Alternatively, we could add these plots and a brief discussion about the eta coverage in the seciton about tracking efficiency. To be discussed. (LE) [plots on next page]

• L73-74: We had even larger bunch spacing in the beginning, I think we• reached 50 ns in 2011 or perhaps end of 2010. So re-phrase with• somehow saying that 50 ns was the minimum buch spacing for physics• data taking. (LE)

• L 133 would be nice to give the distance from the TED to LHCb (EJ)• L189: Where does this number come from? We've discussed the sensor temperature

several times when looking at I/T and I/V curves. Do we really know the value (and the error!) that well? (LE) [chris - don’t remember source – ask in meeting ]

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Section 1 –new plots

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Interaction region

Section 2 – Sub-system -1• L219 Should it be <1s? (LE)

• L268-269: We could add the luminosity loss for 2012 as well here, saying that it is x and y for 2011 and 2012 respectively. (LE)

• L265-272: It would be nice to add the approximate number of automatic closings during Run I here. I tried to extract it from the elog entries once and got to somewhere beyond 500. Perhaps Malcolm knows a more clever way of doing it, otherwise I can have a stab of elog searches again. (LE)

• L.284 A reference to Fig. 5 appears before a reference to Fig. 4, should the order of these figures be swapped? [chris – on purpose discuss]

• L. 292-295. I think the paper doesn't have to give a historical overview of what has been done and thought right in the past, but has been improved upon in the mean time. So get rid of the sentence "Tests have been .... now been improved.” (EJ)

• Fig. 5 top right one• I have seen much nicer figures in which the individual R and P-sensor can be seen.

Cutting harder on data makes it nicer. (EJ)

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Section 2 – Sub-system - 2

• L. 341 "tolerance of 2.4 mm that was reserved for mechanical imperfections of the foil". This is a very misleading statement. Wish it were true !! (EJ)

• Figure 2: Figure is too small, use equation to force $t=6\,\mathrm{hours}" onto one line. (DH)

• Page 5, footnote. PVSS was not developed by Siemens. It was developed by ETM. That was then bought by Siemens what renamed it to WinCC open architecture. Since Run 1 only had PVSS we should refer to ETM. (EL)

• Figure 4: Axis titles are too small on the left figure. When it is re-done we might as well increase the size of the axis labels as well since they are a bit on the small side. (LE)

• Figure 5: These figures look like they are in a compressed format, probably png. I think we have to change them to PDF otherwise they look a bit blurred. Also the axis labels and titles are too small (apart from bottom right) so those have to be enlarged if we display them 2x2. So I'm afraid we'll have to ask Tom to remake them in PDF with larger text. If so, perhaps we could make the bottom right one in B/W as well the colour doesn't add much and it would look nicer if they were consistent (LE). [chris – huge files, we have pdf]

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Section 3 – calib./monitor/sim. -1• L373-374: What is referred to here is not electronic cross talk. For anyone outside the

VELO this sounds like it is cross-talk between different signal pairs in the same cable. I think it has to be phrased something like '... influence on the inter-symbol cross talk between channels transmitted consequtively on the same analouge serial link.’

• L391: cross talk -> inter-symbol cross talk• L393: cross talk -> inter-symbol cross talk (LE)• Line 416: Technically not "the Landau" but "the straggling function” (DH)• L. 476 + 503 + 686 pedestal following + other common mode noise algoritm + cross

suppression algoritm. More or less the same as the previous point: three times something is described which is not used in practice. Please remove. (EJ)

• Line 503: Was the second level CM correction ever turned on? I seem to remember we did for the 2012 running, but may be mistaken. (DH) I don’t think we did (chris)

• Section 3.4: It should mention somewhere that the pipeline column numbers are reset synchronously for the whole VELO and the consistency check also confirms the synchronisity of the VELO. (LE}

• L620: The energy deposition in the sensor is supposed to be Landau distributed. The convolution with a Gaussian comes when you include front-end noise, so this has to be reformulated to reflect that. (LE)

• Line 670: Could mention the "feature" is well simulated (it is both photon conversions and during 2011 about 2% of strips hit by two particles in jets). (DH)

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• Figure 18: The legends are too small, can they be remade with larger legends?

• L. 809-813 (high multiplicity events)• Did I completely forget about it or is this new ?? I assume it is possible to get reference to

a presentation in a VELO-meeting on this. Besides that, I think it is too detailed and can better be removed. (EJ)

• Work – My memory is observation was Marius Bjornstad, explained by Martin van Beuzekom.

• Couldn’t find good presentation on this in velo meetings• Though Martin has so many presentations its difficult to search !• Here is one from Marius

https://indico.cern.ch/event/121567/material/slides/0?contribId=2, p12• Shows the regular pattern of noise but not the explanation.

• L868-869: It would make sense to give these numbers for the end of Run 1 rather than the end of 2011, see comment regarding Table 1. Table 1: Would it be possible add a column with these numbers at the end of Run 1? It might be a tall ask, but it looks a bit strange not reporting on the bad channels at the end of Run 1 as it has changed between 0 and 1.2 fb-1. (Also, we can remove the fluence number on the 5th row as they are redundant. And perhaps add some \vspace before the 5th row to separate the two parts a bit. (LE &EJ)

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Section 3 – calib./monitor/sim. -2

Section 4 – System perform -1

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Updated Fig. 22. (PC)

• Some figures really need a face lift: Fig. 22 the colours and line thickness (EJ)

Section 4 – System Perform -2

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• Table 1 on page 34• I think the numbers for 2.3 fb^-1 should be there also. It is a year ago since we stopped

taking data, so we should have the numbers by now. (EJ)

• The proximity of the detector to the beam means that the inner regions• of the n +-on-n sensors have already undergone space-sign charge inversion due to

radiation damage.• needs rewriting given the delay in the paper: quote a luminosity up to which results are

quoted rather than "already". (DH)

Section 5 – Phys. Perform -1• Figure 25: Would be good to state the average number of VELO clusters in the caption,

perhaps for min bias and b events. Even better if the distribution of the number of tracks could be overlaid in the plot, but that is probably asking too much. (LE)

• 1026- 1128, Section 5 on alignment. worst written part of the paper. Not clear, too much details and not written with enough distance. Somebody should edit it. (EJ)

• L 1116, 2 half distance (SB) with ted data taken at diff. temperature the distance between the two halves changed by ~130 micron, comparing ted data at "high" temperature with collision data  the difference is about ~170 micron. I would suggest to replace 130 with 170, as this is the current best knowledge (I don't know why there was a difference between the ted data at colder temperature and collision data). (SB) – also comment from LE

• L1128 1um -> few microns (and abstract, ). (SB)• Drop figure 28 (SB)• Fig. 28 numbers and data points too small (EJ, LE)• Figs. 30 and 31 legends along the y-axes too small (EJ)• L1146: Should this be the 'thickness x' instead of width? It is actually not clear from this

description what the quantity x is.

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• L1173-1181 and Figure 30. We could probably remove this section. It is one of many different historical studies and for the others we normally just give the bottom line. So if we are looking to reduce the lenght of the paper this is one thing that could go. (LE)

• Sub-section order: Should we swap the order of 5.3 and 5.4, it would feel more natural to describe PV resolution before IP resolution. Both to go from the IP and out, and also because we mention PV reslution and the number of PV tracks in the IP resolution section.

• "and a vertex resolution of 13 m in the transverse plane and 71 m along the beam axis is achieved for vertices with 25 tracks.”

• is true but saying it is the primary vertex resolution would be more meaningful (we can not active that for nuclear interactions in the sensors). (DH)

• l 1195: remove "in CP violation and rare decay studies" - it seems somewhat limiting (CT)• l 1197: consider introducing $N$ here rather than on line 1217 (CT)• l 1219: "C can be thought of as the best resolution possible, given multiple scattering"

makes no sense because C is negative! Could just say "where A, B and C are constants". (CT &LE)

• L1221-1228: I think we should make a comment saying that the performance was the same in 2012 or give a number. Just a brief one, since we are supposed to cover the whole Run 1. (LE)

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Section 5 – Phys. Perform -2

Conclusions• You could in the conclusion say based on the experience with r/phi strip geometry we

agreed to replace the detector with a square pixel based device at the first opportunity.(DH)

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