R&D of a Novel High Granularity Crystal Electromagnetic Calorimeter
Round 1
Reviewer 1 Report
Comments for author File: 
Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
General comment:
The paper gives an interesting overview of ongoing R&D activities for the development of a novel high granularity crystal electromagnetic calorimeter without however entering in the details of the many studies presented.
In general, the content and quality of all figures can be improved. In particular the size of the axis labels and legends should be increased.
Specific comments:
L60: Higgs physic → Higgs physics
L68: “include silicon vertex detector → include a silicon vertex detector, a Time Projection, …
L71 SiW-ECAL → the SiW-ECAL
Figure 2: (b) caption: “form” → “from”?
Figure 3: the labels of the axis and the text of the legend are too small to be readable, please increase the font size
Figure 3: the text of the legend (describing different colored curves) could probably be simplified and the made more clear
L79-82: Could you explicitly mention the molier radii for the crystal ECAL under study and for the Si-W used in the comparison?
L87: “higher energy threshold” please clarify, is this the threshold on the calorimeter “hits” used for reconstruction? Do hits correspond to the energy deposited in a single crystal bar or the energy estimated for a reconstructed “cube”?
Figure 3: could you comment on the dips around 160 mm on the bottom plots? These seem related to geometry gap (in the crystal) but shouldn’t the gap be at +/- 200 mm for 40x40 cm² super cells?
L91: is there any selection on whether the pions start showering in the crystal ECAL section? Is the crystal calorimeter sensitive to a pions which does not start showering or the energy deposited by a MIP is below the hit energy threshold?
What dataset was used to study the separation efficiency? Are these jets from real events or a particle gun?
L98: it is a representative → it is representative
Figure 4: the two histograms show very different number of events, what is this due to? Is the same data set used for both plots? Are different cuts applied in the two cases?
L114: “ghost hits” is jargon and should be defined.
L114: time information is mentioned. It would interesting to understand what is the time resolution required for this to be effective.
Figure 5: axis labels in the top right figure are two small too be readable. Either remove them or increase the font size.
Figure 5: the parameters alpha and rho in the Hough space are not defined
Figure 6:
1) axis labels and legends are too small. Please adjust.
2) in the caption of the left figure: clarify what is the threshold referring to (energy threshold on hits?)
3) in both figures, how is the p.e./MIP defined? What is the amount of energy deposited by a MIP in MeV?
L134: can all candidate crystals be produced with the required length (40 cm)? It seems pretty long compared to typical crystal ingot dimensions. Could a reduction of the crystal length by a factor 2 be considered?
L148: the Geant4 simulation of PWO must include an intrinsic light output (photons produced per MeV); what was this assumed to be? Please clarify in the text. Can the manufacturer of the crystals tested be disclosed? There are often sizable variations in the light yield of crystals from vendor to vendor.
L161: this is most likely true for BGO which has a O(100 ns) long decay time. It is less true for PWO. Consider adding a comment.
Figure 8: (c) and (d) add a legend to clarify the blue and red pulses (I assume the trigger and sipm output signal). Add horizontal axis with the time scale and possibly vertical aixs for the amplitude (which unit?).
L185: how collimated is the Cs-137 source? Does simulation assume the same spatial (solid angle) distribution of gamma-rays interaction within the crystal as for the real source?
Figure 10: as in a previous comment for PWO, could you specify what is the intrinsic light yield assumed for BGO in the Geant4 simulation?
L199: suggested change: “high requirements” → “tight requirements”
L211: what is the amount of dead space you allocate (or that you are aiming at) for PCB, readout (cooling?) between neighboring super-modules? Could you consider adding this information somewhere in the paper?
L244: “And key requirements [...]” → “Key requirements […] have also been [...]”
L250: “help to accumulate” → “help accumulate”
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
This paper gives a good overview of R&D activities of a new design of electromagnetic crystal calorimeter for future electron-positron colliders. I understand that the new layout will provide good 3D granularity to PFA with the reduced channel count for cost and power reduction. It is a great concept. In my opinion, the paper is fine to publish in present form. In the following, let me describe what I would like to see in your future reports. (1) About ghost hits and minimizing them with time information: What is the level of time information useful to reduce the ghost hits? 10 ps, 100 ps, 1 ns? How to achieve it with BGO (300 ns decay time, 8000-10000 ph/MeV) or PWO (10 ns, 100-200 ph/MeV)? Are today's SiPM and readout electronics good enough for the timing measurement? (2) About dead material/gap between modules (Super-Cells): How much material and gap do you expect between modules? Do they have significant impact to resolution and PID? If the impact is large, can software algorithm recover the effect? (3) About NDL EQR06 SiPM: It is a new type of SiPM and fast signal with wide dynamic range according to your plot and NDL's datasheet. It will be interesting to see its performance on prototype in test beams. (4) About Higgs benchmark with jets: Calculate Higgs mass distribution with the cross-bar structure instead of 1 cm^3 in fig.4. (5) About crystals: Do you consider crystals other than BGO and PWO?Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The paper has been significantly improved
