CWR Review

Comments from Pierre Marage:

CFT-09-020_comm_pm.txt P. Marage - ULB - Brussels Comments to CFT-09-020 04/10/09 Dear Authors and ARC, Thank you very much for this very interesting presentation and discussion of the commissioning of the HLT. Your paper demonstrates the good preparation of CMS for data taking. My comments / questions below, coming from a non-expert, are mostly details, asking for some more explanations or suggesting some changes in the writing. Thanks again, and congratulations ! Pierre

Thank you very much for your comments and in particular for your suggestions. They greatly helped improve the paper. Our responses are below marked in red.

Abstract l.2 drop "candidate": since they were deployed, they are not candidates

l.3 drop "online" - triggers are necessarily deployed on-line

l.4 "streams" and "primary datasets" are undefined. This "jargon" should not appear, I believe, in the abstract.

Maybe "the online grouping of triggered events into streams and primary datasets is discussed."

l.5 "the operational performance of the trigger menus in terms of the efficiency of the muon HLT algorithms is reviewed." could be simplified, I believe: -> "the operational efficiency of the muon HLT algorithms is presented."

l.8 I would not use "along with..." in the abstract.

I suggest a separate sentence: "Plans for commissioning the HLT with collision data are introduced."

All comments above have been incorporated.

Section 1

2 The following sounds inconsistent: "The CMS experiment is (...) detector" I suggest "The Compact Muon Solenoid (CMS) detector [1] is one of the two ..."

9 "data-acquisition" I suggest to use "data acquisition" with no hyphen - cf the CMS "CMS Guidelines for Authors" - see https://twiki.cern.ch/twiki/bin/viewauth/CMS/Internal/Publications

14 idem for " data-taking" - please search throughout the paper

21 I suggest to consistently use the passive voice in this paper.

Passive voice seems to be the favoured CMS use (see the "Guidelines" and the first publised CRAFT paper CFT-009-003). In addition, the passive voice is used throughout the paper, except here and - suddenly - in sections 5.3 and 6. In the present case, in addition, the first sentence is with active voice, and the following ones with the passive voice - should be uniformised.

All comments above have been incorporated.

Section 2

42 What I find missing for a self-contained understanding of the paper is a (very short) presentation of the L1 triggers. I believe this is fundamental, since L1 is the basis for HLT superstructure. You don't need to get into details, but I suggest - to give a couple a significant examples - to quote an order of magnitude of the number of L1 triggers. This paragraph may be the right place to provide this information.

Section 3.1 (first paragraph) has a brief description and examples of L1 triggers used during CRAFT.

46 "(quickly)" - avoid parentheses -> "that provides, quickly, the large rejection factor...", or something similar

51 blank after Ref.

53 I suggest to move the footnote at the end of next sentence, l. 55. The reason is that the footnote refers to the "regional" concept, which is not defined yet.

54 "regional" is undefined. My suggestion is to define "regional" implicitely, by putting it between quotes, which will indicate to the reader that "regional" means "from specific parts of the detector".

63 "menus" : this is jargon - as shown by the fact that you felt useful to put it between quoting marks when it appears for the first time in the paper (except for the abstract). I believe it is necessary to define is explicitely here. For instance, you could add in l. 64 a new sentence ot the type: -> "In this paper, a "menu" is defined as a set of HLT algorithms based on L1 triggers, combined with additional detector information, leading to a decision concerning the data acquisition of a specific event." (my attempt is certainly not satisfactory - please give a better definition !)

All comments above have been incorporated.

Section 3 73 Is there a ref. for "which had already undergone extensive commissioning" ? The sentence has been removed.

74 please add "L1" before " “pass-through” triggers, " - as you do further on, e.g. in l. 100 This is necessary to clarify what “pass-through” means Done.

75 "bits" -> "trigger" Changed to "triggers"

Section 3.1

81 No capitalisation in titles of subsection - cf. your practice e.g. in section 5.2 Done.

83 after "128 “Algorithm triggers” ", you could add: ", defining the HLT menu, " The so-called "Algorithm triggers" are input to HLT and define L1. Rephrased this sentence.

84 comma after "event" after "based on", I suggest "physics-driven", to distinguish from the technical triggers" "L1 trigger objects" are not defined. I suggest to add: ", such as a muon, a jet, an electron or photon with energy above some threshold". Rephrased this sentence.

85 drop "can" "Can" should be kept, as triggers can be masked: information is provided but may not influence the decision to "keep" the event. drop "final" Done.

86 replace "receive input directly" by "evaluate input ((drop "directly"))" Sentence rephrased. "for special purposes such as detector diagnostics." What else ? -> "for detector diagnostics." Some other examples of technical trigger use include noise monitoring, beam pickup, and min bias triggering. Re-phrased by adding monitoring.

87 I don't understand "L1 single-object algorithm triggers": in the rest of the sentence, you do not give examples of algorithms, but of objects -> "L1 single-object triggers" The algorithm triggers were described earlier, and the definition of an L1 object has been added.

88 what does it mean "with no additional selection" ? I suggest to drop No energy/momentum requirement is applied. This is implied by the improved definition of the algorithm triggers and the description of the other single-object triggers.

89 electrons / photons : 1 GeV energy or pt ? presumably : "an electron or photon with transverse energy above 1 GeV" (("1 GeV electron" is not what you mean)) Done.

92 "would" duplicated Done.

95 "higher-quality L1 objects" - what does this mean ? - and how is this a consequence of the fact that "As each trigger in the HLT is configured to receive a selection of events based on L1 information, this allowed the more complex HLT triggersto be seeded by higher-quality L1 objects."? Presumably you want to say something like (?) -> "As the HLT trigger use the full (?) L1 and additional detector (?) information, they could use more complete information on L1 objects" (??) Examples of "higher-quality" objects includes jets with higher ET, two muons instead of one, etc. Sentence rewritten.

96 "The triggers present in the menus deployed..." -> "The HLT trigger menus deployed..." Rephrased.

98-99 I don't understand the sentence: "All triggers process every event accepted by L1, so the more complicated triggers provide additional information regarding the event quality beyond the L1 decision." Maybe you mean: "All HLT triggers, which process every event accepted by L1, REQUIRE additional information ON the event THAN FOR the L1 decision." ?? The previous sentence indicates that some additional processing beyond L1 information is necessary in order to satisfy some HLT triggers. The additional processing consequently provides more information about the event..

103-104 I don't understand "and was present to ensure that no useful physics events were lost." To keep physics events is the very definition of the triggers. What do you mean by "ensure" ? Triggering is needed to reject rather than accept events. During commissioning the HLT was operated in "mark and pass" mode. The sentence has been rephrased.

105 drop "-triggered" Done.

107 "orbit" is not defined, and should be explained I suggest something like the following: -> "These events are TAKEN (not "occur") at a rate of 100 Hz ((moved here from 109)), at the end of ABOUT ((not roughly)) 1% of all LHC orbits, during THE ((drop a designed)) gap in the proton bunch STRUCTURE [7]. The events are designed to occur at a specific gap (one of many) in the LHC orbit. "Occur" seems more appropriate, as "taken" implies the rate may exceed 100 Hz". Rephrased this section.

This gap, devoid of protons in either LHC beam, corresponds to ??? bunches on a total of ???." I think it would be useful to give here the example given in l. 251-2 "For example, calibration events allow for the monitoring of the drift time by pulsing of the muon drift tube chambers." Continue with : "The LHC bunch structure was emulated ...a calibration event." See Above. Other reviewers suggest removal of specific examples for calibration events, so nothing added here.

Drop sentence in 109-110 See above.

111 "were" -> "are" (this is generic for random triggers) Done.

114 "were prescaled by the HLT" - this is always true => "were" -> "are" Done. - and it is evident that random triggers are "prescaled", i.e. not for every bunch crossing. Or do you mean something happens in addition at HLT ? -> "The L1 random trigger RATE IS DEFINED SUCH AS to ensure..." The random trigger rate can be adjusted at L1 and at the HLT to control the rate. The sentence has been left as is.

116-117 I suggest to drop this sentence, which is a repetition of 100-101 This sentence is necessary to inform the reader that the HLT is running in "mark and pass" mode.

117-120 I also suggest to drop this sentence, which overlaps with 131-132 and, as mentioned, with Section 4 This sentence describes the purpose of commissioning the HLT during CRAFT, and does not overlap with the sentence you mention. It additionally motivates Section 4.

121-130 I suggest to drop this paragraph. - it does not really provide additional information compared to what as already been explained (121-123; 123-125 is also implied by what has been said); - or it brings information for internal use which, I believe , is not used later (125-130). Done.

134 add "tracker" after "pixel" Rephrased.

137 after "event", I suggest to add "due to particles crossing the detector" "the event" -> "it" I suggest to add quotes around "physics" Rephrased.

141 after "capturing", I suggest to add "particle-related" Sentence has been removed.

146-146 "collection of cosmic ray data at CMS. The selection and storage of the cosmic ray data required nothing..." can be simplified as -> "collection of cosmic ray data, of which selection and storage required nothing..." Sentence removed.

147-148 It is not an opposition but an addition => "However" -> "In addition" Removed.

168 "searches using" -> "in" Changed "using" to "in". Believe "searches" is still relevant.

177-179 I don' understand "This trigger could only be implemented during commissioning efforts as all triggers need to be seeded by L1 information during colliding beam operations." Can you rewrite / explain ? Rephrased.

Section 3.2

184-185 I believe the sentence will be more clear if you move "offline" and "online" and make a couple of small changes "same software to run on Monte Carlo and previously collected data events offline and record collision or cosmic ray data online. -> "same software to run offline on Monte Carlo SIMULATIONS and previously collected data events, ((comma)) and TO record online collision or cosmic ray data." Done (omitted the comma).

187 fn. 2 "streams" and "primary datasets" are not defined - is this footnote really necessary ? If yes, please put forward ref. to section 4 Removed footnote.

189 drop "in order to exclude any potential problem." Already stated - does not add anything Removed sentence.

195 drop " (event) " "Events" are the data units, and thus a useful inclusion in this sentence.

196 drop "event" See above.

197 streams is not defined.

I suggest to put it between quotes, and to refer to section 4 -> " output "streams" (see Sect. 4) according" Done.

Section 4

246 what are the "HLT reconstruction by-products" They are never defined, although mentioned e.g. in 273, where they are claimed to be "essential" I could not figure out what you mean...

Added short description.

254 "high-rate" : no hyphen "had" -> "have

Fixed.

261 I suggest to simplify the writing CFT-09-020_comm_pm.txt -> "The ((not these)) PDs ARE defined, within a stream, BY GROUPING a set of triggers that perform ((present tense)) similar selectionS ((drop "were grouped into a primary dataset")) (eg. all ..."

Thank you! Changed.

Section 4.1

267 space after "stream"

277 I suggest to replace "data used in the online DQM" by "data flow", which keeps the idea and avoids repetition of DQM

Both done.

Section 4.2

298 what are "hits of the crystals" ? -> "electromagnetic clusters" (?) Reconstructed hits - remove "of the crystals". Reconstructed hits are grouped into clusters of 5x5 crystals. Contiguous clusters are grouped into super-clusters....

300 "Phi" -> $\phi$ Symmetry : no capital S DONE

301 what are "all reconstructed hits of crystals" ? -> "all reconstructed energy deposits above threshold in the ECAL crystals" (?) Reconstructed hits - remove "of the crystals". Reconstructed hits are grouped into clusters of 5x5 crystals. Contiguous clusters are grouped into super-clusters...

303 idem 300 DONE

308 Track : no capital T DONE

309 "measure the single pion response of the calorimeter" -> "measure calorimeter response to single pions" DONE

315 would be good to say why "No calibration constants were derived" Need collision data for this. Have removed this line since it does not add significant information.

Section 5.1

327 To help the reader, I suggest to add "(see Sect. 5.1.1)" after "filter units"

328 ... and "(see Sect. 5.1.2)" after "HLT processing" DONE.

328-331 I suppose that "it is generally subject to less restrictions" refers to "the latter". - what do you mean exactly ? - could you clarify and simplify this sentence (the former / the latter is not easy to disentagle, especially since there are here two reasons which are not written in a symmetric way "there are limitations" ... ""it is generally subject" DONE.

333 "at RATES up to ..." DONE.

343 "any TYPE of events, ((comma))" DONE.

344 "bits" -> "decisions" DONE.

362 "muon TRAJECTORY" DONE

363 "requirements" -> "constraints" ("required" already in l. 362) DONE

365-367 cf. my general comment on avoiding "we" -> passive voice.

in the present sentence, this would even clarify the writing, which is presently particularly difficult to follow, at least for non-English natives. -> "Even though not many events ARE EXPECTED to satisfy the muon triggers that require tracking, THOSE THAT SATISFY THIS REQUIREMENT CAN BE USED to obtain DATA ON ((not monitor)) the performance DONE

368 CMS usage is "Fig. 1" inside a sentence. In addition, be consistent with you notation of abbreviated notation of "Sect. xx" DONE I suggest not to quote here the cumbersome name HLT_L1MuOpen We should keep this trigger name because it is a key to understand the left plot in figure 1. Instead, we add some more text.

369 I do not understand how one can define "a L1 muon without any momentum threshold or quality cuts" - there must necessarily be some requirements ! The HLT_L1MuOpen trigger path is fired if there is a L1 muon reconstructed by L1 trigger. The Open trigger doesn't require momentum threshold like L1Mu20, and also it doesn't require quality cut like L1Mu

370 "good-quality run" -> "good quality run" (? - cf. Guidelines) DONE

370-371 "This allows us to study the performance of the muon HLT triggers". You give only one example, the efficiency as a function of eta. I would not call this "the performance of the muon HLT triggers": - are there other variables / studies ? - if not, the wording is too general and overdoing I agree and remove the sentence.

372-373 "L1 muon eta" -> "the L1 muon pseudorapidity eta" DONE

373 From the caption of Fig. 1 (right), I understand that it presents the ratio L2 / L1 as a function of eta. I presume the L1 muons that are referred to are the HLT_L1MuOpen muons of the left figure. But here one says that only the L2 muons in the second bin are used. The efficiency should thus, by construction, be 100% What did I miss ? I think "for this study" in 373-374 make people confused. It is changed by "for this plot"

Can you please clarify both the text and the caption ?

Section 5.2

383 to help the reader, I suggest to write "offline DQM, however, are two-fold" (or "are the following") fn 3 "it's" -> "it is" DONE

Fig. 1 vert. axis "rate" -> "efficiency cf. comment 368 - avoid HLT_L1MuOpen hor. axis too small - not readable these trigger names are CMS HLT jargon. The last 3 triggers are not described in the caption - the reader can (maybe) figure out the content of the first one, but not of the other two. I thus suggest to keep only the first 3 bins caption l.2 "L2 muons to L1 muons" - see 373 : which L1 ? HLT_L1MuOpen ? other L1 ? l. 6 drop "has a few events that pass" -> "corresponds to a few entries" (this histo. does not contain events but efficiencies)

Description improved.

Section 5.2.2

In sections 5.2.2-3-4, please be consistent with the rest of the paper, and write - "L1" for "level-one" (trigger, data, etc.) - "HLT" for "high-level trigger" FIXED

396 eta-phi -> $\eta - \phi$ DONE

401 drop "plotted" ("objects" are not "plotted") DONE

402 "unbiased sampling of objects for efficiency" -> "unbiased sampling, ((comma)) IN VIEW OF efficiency" REPHRASED

406 "is an estimator of the test path trigger efficiency “turn-on curve” " the “turn-on curve” is not an "estimator" => drop “turn-on curve” -> "is an estimator of the test path trigger efficiency." DONE

413 "planned for future exercises" is irrelevant: when the paper will be published, real data will hopefully quickly become availalbe => no more "exercises" ... -> "Although planned for data taking, automated quality tests and data certification were not yet deployed" REPHRASED

Fig. 2 To be redone (quality) axes $\phi$, $\eta$ drop the title CMS Preliminary -> CMS 2008 It was difficult to reformat the originally chosen figure, as the parent root file was not readily available. It has been replaced with the equivalent occupancy plot for CRAFT08 run 66676, for which the .root file could be readily regenerated. The figure now abides by tdr standards. The caption has been elaborated. The text has been elaborated to describe how the geometry of actively triggering DT sectors can be identified through the offline monitoring.

418 "however" -> "but" DONE

419-420 I do not understand the sentence "will allow for unique monitoring uses there" Do you mean "will make offline DQM an important diagnosis tool" - or something similar ? REPHRASED

Fig. 3 I suggest to drop this figure, which does not bring any useful information Figure 3, and references to it, have been dropped.

425 "cosmics" -> "cosmic rays" DONE

Section 5.3

428 and elsewhere : "CPU-time" -> "CPU time" - no hyphen

Done

432 avoid parentheses -> "a few runs, with different menus"

Done

438 I suggest to swap the two times (unpacking and algorithms), and to avoid "as well as" -> "includes both the data-unpacking time and the time taken to execute the algorithms."

Done

439 Since you propose to have a footnote, this sentence could also go in the footnote Table 1 central column, third row : no capital for Tracker

Done

446 drop "as well as", and commas needed : -> "that used tracking information, a jet trigger, and a low threshold..."

Done

450 "allowed us to gauge" -> "allowed gauging"

Done

451 -> passive: "One algo. was found, that was not..."

Done

454 Drop "We found that"

Done

fn. 5 ?? "we expect" - can this not be measured ? also "different parameters" is vague.

Fixed

Section 6

463 "build" -> "have built"

Done.

464 passive voice -> "During CRAFT, physics-based ...L1 decision were successfully integrated"

Done.

466 "our" -> "the"

Done.

472-475 you announce three lessons. Would be more clear if each of them corresponds to a single sentence. -> group the sentence of 472-3 and that of 473-5, by separating them with semicolon instead of full stop.

Done.

478 drop "we see that"

Done.

482 "and design" -> "or design"

Done.

482-483 "In 2009 we have improved ... and can provide ...". What do you mean here "can provide" ? In fact, the first part of this sentence is a repetition of 463-464, and the second part is unclear => to my opinion, you could drop this sentence

Re-phrased.

Ref. [5] This seems to be an internal CMS note => should not appear among references.

This paper has very recently been published. Reference has been updated.

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