sPHENIX HCal discussion

[Edouard Kistenev <kistenev AT bnl.gov>]

I am hesitant to go through with text modifications and will wait for the next round of corrections to do this. For now below are few comments which are really important (could already be present in John’s and Jamie’s lists).

- the resolution numbers in the abstract are for the maximum allowed  so they should be qualified as “better or around”;

- this was not “prototype of one sector”, we usually use “prototype of sPHENIX calorimeter system” qualifier;

- we allow fibers bent at a radius of 25mm which is considerably larger then 15mm in PHENIX PbSc calorimeters which are now  close to their 20th anniversary without any crazing observed in the bend area. Besides fibers in sPHENIX are S-type from Kuraray (really flexible);

- we had no TEDLAR at production time …. what is used is PVC;

- why do we need “minimum” bending radius;

- readout (SiPM’s and preamps are at the outer circumference in both hadr. calorimeters);

- a little strange to discuss HCal calibration in “design" section and EMCal calibration in “results” section. To me the most interesting part of calibration is consistency between “externally” and “self” triggered muon calibrations. The first is useless for the future calorimeter, the second gives a hope to not only calibrate but also to precisely monitor the detector in situ;

- “minimal thickness” of 5.5 Labs is probably a “total minimal absorber depth or thickness" whatever appropriate;

- I would move fig.19 to the first page;

- fig. 24 has its “nose?” rotated on top and “not rotated” at the bottom;

- the statement that hcal resolution is driven by SiPM saturation MUST be proven (I am sure it is not and not signing on it). The nonlinearity in the small prototype with total depth of 4.5Labs (standalone hcal, fig 35, little will change even for the total 5.5) is entirely predictable - with shower penetrating deeper in the structure the sampling fraction drops and the leakage grows. Both have the same effect on measured response. It must be clearly said somewhere that in this paper we ignore to do what is customary done in hadron calorimeter papers - correct for known deficiencies. 

Edward

On Oct 3, 2016, at 1:51 PM, John Lajoie <lajoie AT iastate.edu> wrote:

Dear Test Beam Publication Committee (or TBPC):

    A very nice first draft. I have a number of questions and comments that I outline below.

    (I second Jamie's comment that it would make the review process easier if line numbers were shown for each line in the next iteration.)

    One additional general comment - on *many* of the figures, the text on the figure is way to small to be legible.  I think the TBPC will need to go through all these figures and make another pass at organization and font size before these will be publication-ready.

Regards,
John

JGL Comments:

Abstract:

The electromagnetic and hadronic calorimeter design...

In the third sentence you mention the stochiastic resolution term but not the constant. I think it would be better to say something like :

"To achieve the goals of the proposed physics program, an energy resolution of 15%/sqrt(E) and 100%/sqrt(E) are required for the electromagntic and hadronic calorimeters, respectively.  In addition, the energy resolution function should have a small constant term, <5% for the electromagnetic calorimeter and <20% for the hadronic calorimeter."

Body of Paper:

line 6 - put "jets" in quotes when first introduced

line 8 - the appears throughout the paper: comprises -> is comprised of

"... sPHENIX is comprised of calorimeters and *a* tracking system..."

line 13: is comprised of

line 28-29: I don't understand this sentence.  The requirement on projectivity of the EMCal is to avoid spreading the EM showers out between multiple towers and keeping the shower size contained.  "enable accurate jet measurements" is ambiguous, and not accurate in this discussion

lines 31-35.  I do not understand this argument. Why is the cluster size quoted in MeV, and how does this directly impact the resolution?  The argument we typically make has to do with the size of the underlying event and its fluctuations.  This needs to be stated more clearly.

line 45: is compacted by vibration

line 58 : 11.2 degrees

line 75/Figure 1c:  This just shows the cutting wheel, but does not support the claim that such a cutting procedure avoids damaging the fibers, which is what I expected from the text. Perhaps a closeup of the cut face that supports this assertion would be more appropriate?

Figure 1 (caption): there is no mention of vaccum or vibration to compact the tungsten.  The caption should be updated to include relevant details, or something like "see text for details".  As it is I think the caption is incorrect by omission.

Figure 3(a): This figure (and the text) are way too small to be readable.

line 100: Next, an acrylic...

lines 107-122:  This is described again in the test beam section (almost verbatim), and is really more relevant there than in this construction section. Delete these lines in favor of the description in the test beam results section.

Figure 4: Is (0,0) the center of the light guide? If so, why the asymmetry? This caption requires more details to orient the reader and explain the result.

line 131: groups of four by manufacturer measured gain

line 158: It would be good here to say something "...to represent the sPHENIX magnet and cryostat with an equivalent number if interaction lengths of material."

line 165: "...wavelength-shifting (WLS) fiber ...

line 169: do you need a reference for Kuraray fibers? Will it be clear to the reader what this is?

lines 200-205:  "This process removed microscopic non-uniformities normally present on the surface of the extruded plastic, decreasing aging and improving the ability to withstand pressure without crazing. It also enhances the efficiency of light collection in tiles with embedded WLS fibers. The coated tiles are grooved, then WLS fibers are embedded..."

line 244: show a decreasing trend

line 265: This resulted in a total...

line 268: Sixteen preamplifier boards...

line 272: ...all five SiPMs...

line 293: In each run, four...

line 295: eight

line 204-206:  This sentence "It monitors..." seems incorrect. While short-term gain changes from temperature can be monitored with the LEDs you don't monitor leakage current with this. You just look at the leakage current.

line 331: they are

line 345: This is the first place a blower is mentioned.  Perhaps somewhere upstream of this sentence you need to say something about a blower being used to provide air cooling for the electronics.

line 392: is comprised of

lines 392-405: You need to be consistent here and capitalize both parts of "Interface Board" and "Controller Board", or ideally neither of these since the use as proper names is a bit stretched.

line 411:  ... Two Controllers were used...

line 440: for most sPHENIX R&D

Figure 17: I think this Figure is confusing as we used an internal clock for the test beam. It would be better to have a modified figure that more accurately shows the electronics as used for the test beam.

line 451: RCDAQ allows the capture....

line 472: allows users to...

line 485:  You can't say the momentum spread depends on beam tune and then quote a number?  How about ".. beam tune, and for the T1044 was approximately 3%". Also note this is quoted as 3% here, but the EMCAL section corrects for dp/p of 2%. These need to be made consistent.

Figure 20: Not at all readable

Figure 22:  This will not reproduce well with all the detail in the EMCal modules.

line 575: Section 7?

line 580: ...to produce a combined result.

line 583: described in Section 5.

line 588: a few percent contamination...

Figure 25: I don't think this is too detailed to included

line 627: hadrons and muons

line 629: .. event, the calibrated EMCal tower energy

line 637: The energy resolution...

Figure 27: caption last sentence "stem from..."

line 650: The energy resolution....

line 655: emphasizes improving...

General comment on EMCAL results: In the text we quote resolutions with the beam momentum spread subtracted, but all the plots show it without the subtraction.  This is confusing. The plots should be made consistent with what is quoted in the paper. (Figs 28, 29, 31, 32).

Figure 29,32: (caption) last sentence. You should ideally repeat the full caption with each figure; the reader shouldn't have to bounce around.  As a second-best option you could say "Figure details are the same as in Figure 28."

line 709-711: This is thought to be due to....

line 735-736: I think we discussed this in the HCAL meeting at some point. If this is e/pi, then a plot dividing the two curves is appropriate, or if it is constant, quote a number.

Conclusions:

The conclusions section needs to be tightened up.  Sentences like "The calibrations are described in Section 3.4/" are useless in this context.  You quote the energy resolution for the different calorimeter sections but you should also quote the combined result as well.  You should also state again in the conclusions that the measured performance is consistent with sPHENIX requirements.

On 9/26/2016 4:55 PM, Ron Belmont wrote:

Dear HCal and EMCal enthusiasts,

The T-1044 2016 paper is ready to be reviewed by the experts prior to our release to the collaboration at large.  The draft is linked on the test beam publication page (https://wiki.bnl.gov/sPHENIX/index.php/T-1044_publication) and can be accessed directly here: https://wiki.bnl.gov/sPHENIX/images/e/eb/Beam-test-results.pdf

Please note that, as always, editing the Overleaf is not allowed without first consulting with the section chairs as listed on the test beam publication page.

In principle we have no customary or official deadline for comments at this point, in contrast with official collaboration release, but we do want to release to the collaboration as soon as possible, so please send comments not more than two weeks from now (the sooner the better).

Best regards,

Abhisek, Jin, Megan, Vera, and Ron (the test beam publication committee)

--

-----------------------------------------------------
Ron Belmont
Postdoctoral Research Associate
University of Colorado, Boulder
ron.belmont AT colorado.edu
-----------------------------------------------------

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John Lajoie

Professor of Physics

Iowa State University

 

(515) 294-6952

lajoie AT iastate.edu

Contact me: john.lajoie

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