The LUCID Detector for LHC Run-2†
Round 1
Reviewer 1 Report
The paper discusses LUCID, the luminosity monitor of the ATLAS experiment at LHC.
The paper presents the improvements in the LUCID-2 detector compared to the previous detector LUCID-1. It does so in a somewhat technical manner, and seems as it is directed mainly for those who are interested in the technical design of the instrument and the results it can bring.
It discusses error sources, specifically the pile-up of errors below threshold, and mentions algorithms that are used to overcome the issue (though the algorithms themselves are not presented, and I hope they are published elsewhere).
The paper is well written, and sufficiently informative.
I personally don't care much for figure 1 but figures 2 and 3 are very important for the paper, and the data in those figures is well presented and clearly demonstrates the discussed improvement.
Indeed, the bottom line is the improvement in performance, that I suspect to be the interesting part for most readers.
I would be happy to see section 3 (Principle of Luminosity Measurements) more expended for the benefits of the unfamiliar reader. I don't know if the page limit allows it or not.
Other than that I don't have any meaningful comments or suggestions for improvement.
Author Response
Dear reviewer,
this communication was in a detector-dedicated session which motivates the fact - I think - it is rather technical.
However, I agree clearer hints on the principle of luminosity measurements could be provided. I thus tried to expand the text related to it by stressing the key points but without repeating details included in the references.
In additions, deep discussion of ATLAS general results is subjected to quite a long internal approval process, which is not required for technical communication - public results can of course be reported.
Rephrased/added parts are in italics. The title is sligtly modified because it had already been used somewhere else.
Your comment surely helped in improving the quality of the manuscript.
Reviewer 2 Report
Nice paper, only minor comments:
- "Several detectors in ATLAS provide luminosity information,.." Could be useful to the reader to mention the names etc. of other key monitors that are complementary to LUCID-2? E.g. ones in fig 3
- I think it would be helpful to the reader to have a table comparing the key properties of LUCID versus LUCID-2 e.g. maximum pileup, minimum bunch spacing, and so on compared
- Beginning of section 2 kind of went straight into the details without fully explaining the history of LUCID and LUCID-2 etc., possibly could be helpful to have an extra sentence or two at the end of section 1 or beginning of section 2 more fully explaining the move from LUCID to LUCID-2, and possibly were there any prior detectors that the first LUCID was based on, or is related to?
- Does LUCROD stand for anything?
- Seemed a little light on references but if the authors feel that they have linked to all key papers then it is acceptable
Minor phrasing comments:
- Abstract, "The overall detector performance in RUN-2 and preliminary results on 10 luminosity measurements are presented as well." is ok, but "as well" is a bit colloquial, suggest perhaps "In addition the overall detector performance in RUN-2 and preliminary results on 10 luminosity measurements are presented." or similar
- The second sentence in section 1 "As a consequence,... " was a bit long and unwieldy, would suggest separating into two sentences
- End of section 3, "on possibly new ones" change to "on possible new ones"
- "LUCID-2 has provided luminosity to ATLAS and LHC" maybe should be "LUCID-2 has provided luminosity measurements to ATLAS and the LHC"?
Author Response
First of all, thanks for useful comments.
The new version includes all suggestions, as well as a sligthly modified
title to stress differences to previous publications. In particular:
1) Definition of EMEC, TILE, FCal, TPX, Z and tracks added with proper references as well as few words on pro and cons;
2) A table has been added, although no single number exists for pileup, nor in run 1 or 2 : LHC performance continuously improved over time
3) Few sentences on lucid history added
4) LUCROD stands for LUCid ReadOutDriver in the mind of our group, but this is not written anywhere. In ATLAS-TDAQ jargon, RODs refer to the detector-specific part of the readout architecture. The names LUCROD and LUMAT simply name the corresponding custom VME boards in all official documents, and I'd rather keep it this way.
5) Phrasing improved according to suggestions
Added/modified text in the communication is written in italics to help you identify it. The title was also slightly changed because it had been used previously.
