sPHENIX EMCal discussion

["Dennis V. Perepelitsa" <dvp AT bnl.gov>]

Dear Anabel and team,

Congratulations on this stage of the paper! 

I append some comments below, separated into more “substantial" ones about the analysis / presentation, and more mundane / editorial ones. Apologies for doing this only after the EMCal group-level review.

Dennis

— 

Substantial

L29-L32: I was surprised to see the HF program mentioned here (instead of other possible choices). Since this is a paper on the EMCal test beam, it may be more relevant to pick out photon-tagged jet and jet structure measurements as the example to mention?

L40: in principle, there are measurements in the literature by AnDY: https://arxiv.org/abs/1304.1454 . should we consider these? 

L43: is it useful to add that the EMCal also measures the start of (some) hadronic showers? obviously that is not the point of this paper, but this is still in the introduction and we will rely on that capability during data-taking 

L114: all other physical lengths are quoted in mm and cm, but here inches are used. is there a reason for this? 

L188: awkward to talk about the “accuracy and precision” of the beam momentum — would it be an equivalent meaning to write “the average of the reported beam momentum and its spread” (or dispersion)?

L196: perhaps I am remembering wrong, but I seem to remember the pressure was tuned “separately for each desired energy value” — is that useful to add?

L216: as written, it seems the beam profile was energy-independent in simulation, unlike in data. is that important to point out?

L217: is it important to have these particular numbers identify the towers? they are somewhat distracting (one wonders what the counting system is, what happened to towers 30-35, and why they weren’t chosen). I think it would read in a much more straightforward way if you just call them Tower A and Tower B.

L250: should we add that the “peak” in each energy spectrum was generally assumed to arise from single electrons? otherwise the cuts can sound a bit mysterious 

L263 and other places (L13, L275, etc.): I found the use of “cluster” confusing, since it suggests that a clustering algorithm was used. I think this could be replaced case by case. For example, at L263: “cluster energy” -> “measured energy”, or at L275: “5x5 group of towers”, etc.

L281: I think the paper would benefit from some indication as to why two position-dependent calibrations considered. is it because the cluster-based one can be used in data-taking for energy deposits without a matching track, while the hodoscope-based one requires external information?

L311: why is the response not exactly restored to unity through the calibration procedure? is it because it is restored to unity for 8 GeV particles but Figure 7 shows 12 GeV particles? should we point this out?

Fig 8 and Fig 9: should the Simulation legend entry also have a linear “E” term? (it only has the E^2 term written)

Fig 8, 9, Table I, II: is a position-dependent correction used in the simulation? if so, which one and should it be specified like it is for the data? (apologies if I missed this in the text)

L336: I found it interesting that the differences in the extracted constant between the hodoscope- and cluster-based results are anti-correlated. that is, the actual value of the resolution at some fixed E is less sensitive to the choice than it might first appear (it is the decomposition into two sources that is more sensitive). is this interesting to note?

L353-359: I found the change to the past tense for this paragraph a bit strange (“improved”, “decreased”, “increased”). the past tense would make sense if the design of instrument itself were identical, so that one could talk about a change with respect to something in the past. but as we’ve pointed out, the projectivity and pseudorapidity range is different. so it is just a different instrument. therefore I suggest “decreased” -> “is smaller”, “increased” -> “is larger”, etc.

L377: in the last line of the paper we mention the “requirements of the sPHENIX physics program” which is somewhat vague. should we define these more concretely somewhere in the beginning of the paper? 

— 

Mundane 

general: the paper defines many abbreviations but they are used only sparingly. (for example, “FPGA” and “DCM” are never used once defined on L169-170, SciFi/W is used only once in the Fig 4 caption and could be spelled out instead, etc.). it may make the paper a bit more readable to remove these.

L46: “within” -> “as subsets of”

L51: suggest “64 sectors which extend in z that describe…”

L56: “along phi” -> “along the phi direction”

L66: suggest to delete “1D projective” here, since it is spelled out more nicely at L74

L76: “The final design that will be implemented in the EMCal” -> “The final EMCal design that will be implemented” (“in the EMCal“ sounds awkward)

L108: “The block” -> “A block” ? since there is nothing special about this particular block

L111: awkward phrasing, would “more than 99% of fibers successfully transmitted light” have the equivalent meaning? 

L152: “normal” -> “nominal” ? otherwise I was not sure what “normal” means 

L166 & L167: strange to have successive sentences both start with “Signals were digitized“

L193: delete “from background” (the MIPs and hadrons are the background, no?)

L225: I think “Poissonian” means “like a Poisson distribution”. perhaps it should just be “Poisson” ?

L230: suggest “to an initial energy” or “to a physical energy” ? 

L242: “Different” -> “Various”. otherwise it sounds like one set of cuts were for MIPs and an unrelated set were for hadrons

L244: “electrons” -> “single electrons”

L256: perhaps “50,000” with a comma — not sure what the journal style is 

L262: perhaps “transverse position” ?

L278: suggest “the shower” -> “the EM shower” ? 

L289: suggest to add “as described below” after “were obtained”, to prime the reader

L296 and L306: there is a space before the percentage sign — or perhaps this is the journal style? 

L299: suggest “transverse profile”

L304: consider “by making the distributions uniform as a function…” (“uniforming” reads awkwardly in context)

Table I and II: I would normally render “cm” and “GeV” in roman since they are units. here they are italic — is this a journal style?

L334: perhaps “energy collection efficiency“ ?

L353: perhaps “response of the prototype TO ELECTRONS” and “as a function of INCIDENT position and energy” for a more descriptive concluding sentence?

—

On Feb 4, 2020, at 9:36 AM, Romero Hernandez, Anabel <acr4 AT illinois.edu> wrote:

Dear sPHENIX collaborators,

Attached is a draft of the 2018 EMCal testbeam paper for your review. The target journal is IEEE TNS. The paper includes a draft author list. The spokespeople will inform the collaboration on the procedure for finalizing the author list. We would greatly appreciate any comments, if they could be submitted by the end of the day on February 18.

Thanks to everyone who has participated in the EMCal v2.1 testbeam efforts!

Best,

Anabel on behalf of the EMCal testbeam team

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