Centrality Determination in Heavy-Ion Collisions Based on Monte-Carlo Sampling of Spectator Fragments

Round 1

Reviewer 1 Report

The paper and the results are sound. The main criticism relates to Section 4, which describes the sampling method: it reads like a verbalization of the programming algorithms used. Here the process of sampling should be described in a more physical language high-lighting the main features of the sampling. The rest of the paper is nicely written.

L285:286: should be "excluding very peripheral collisions".

Author Response

We  would like to thank the reviewer for this positive evaluation and the insightful comments. 
We have been able to incorporate changes to reflect most of the suggestions provided.

The paper and the results are sound. The main criticism relates to Section 4, which describes the sampling method:
it reads like a verbalization of the programming algorithms used.
Here the process of sampling should be described in a more physical language high-lighting
the main features of the sampling. The rest of the paper is nicely written.

>> Response: Thank you for pointing this out. We have, accordingly, modified the section 4 to address this point.

L285:286: should be "excluding very peripheral collisions".

>> Response: The peak of the peripheral events is reproducible, while we cannot yet reproduce shape of the knee of the most central events.

 

Best regards,

Ilya Segal

Reviewer 2 Report

The paper titled with “Centrality determination in heavy-ion collisions based on Monte-Carlo sampling of spectators fragments” report a nice and validated procedure based on simulated data for the centrality determination beyond the traditional multiplicity method. The paper is well written and in general easy to follow, while there are some technique details are expected to improve in the revised manuscript. 

 

Some suggestions for considerations:

1. Line 12, the standard terminology for Quark-Gluon matter is Quark-gluon Plasma(QGP). It is better to use this standard terminology, not other names.

 

2, Line 37-41, the author lists the disadvantages for the traditional multiplicity method, it will be good to clarify what’s the most advantage for the new method, and also illustrate which key measurements will benefit from this method.

 

3, Fig1 caption, it would be good to add one sentence on the black dashed vertical lines, namely it’s 10% centrality class instead of only mention 5%

 

4, Line 160-203 is not easy to follow, the author lists this details while there are no general explanation why such formulas are required, some more guidance will be helpful.

 

5, Line 237-250, as for this section 4.2 “charge of spectators”, what’s the relations between this part and section 4.1 and also section 5? Is this an independent procedure/method? Why the procedure described here not been validated in Section 5?

 

6, line 271, -> “minimum bias events were generated”

 

7, In the caption of Fig5, need to add 10% description line similar as fig 1.

 

8, Line 298,  ‘except for”

 

9, Line 310-317, the author commented on the central collisions discrepancy between DCM+Geant and MC-Glabuer for psd energy method, and also commented on the width between multiplicity method and psd energy method. Could author please also comment on the central value difference between these two methods, namely central value difference between Fig 7 left panel and right panel? Can we directly compare the central value for open squares between left and right? Also closed triangles between left and right, there are some systematic differences if we take the central value serious. How should we understand this?

Author Response

The paper titled with “Centrality determination in heavy-ion collisions based on Monte-Carlo sampling of spectators fragments” report a nice and validated procedure based on simulated data for the centrality determination beyond the traditional multiplicity method. The paper is well written and in general easy to follow, while there are some technique details are expected to improve in the revised manuscript. 

>> Response: We  would like to thank the reviewer for this positive evaluation and the insightful comments. We have been able to incorporate changes to reflect most of the suggestions provided.

Some suggestions for considerations:

1. Line 12, the standard terminology for Quark-Gluon matter
is Quark-gluon Plasma(QGP). It is better to use this standard terminology, not other names.

>> Response: Thank you. We corrected that.

 

2, Line 37-41, the author lists the disadvantages for the traditional multiplicity method, it will be good to clarify what’s the most advantage for the new method, and also illustrate which key measurements will benefit from this method.

>> Response: We have, accordingly, modified the introduction to address this point, please see the L 41-45 in the new version. We have add:

This approach might be beneficial for experimental studies that search for a critical point in the QCD phase diagram. Such measurements usually focus on baryon multiplicity fluctuations at midrapidity, hence selecting events based on particles detected at forward rapidity may reduce the nontrivial autocorrelations [17,18].
 

3, Fig1 caption, it would be good to add one sentence on the black dashed vertical lines, namely it’s 10% centrality class instead of only mention 5%

>> Response: Thank you. We corrected that.
 

4, Line 160-203 is not easy to follow, the author lists this details while there are no general explanation why such formulas are required, some more guidance will be helpful.

>> Response: Thank you. We have, accordingly, modified the Section 4 to address this point,
 

5, Line 237-250, as for this section 4.2 “charge of spectators”, what’s the relations between this part and section 4.1 and also section 5? Is this an independent procedure/method? Why the procedure described here not been validated in Section 5?

>> Response:  unfortunately we could not find a working example of a detector to demonstrate the work with a charge of spectators.
We have removed this section in the new version. However, we plan to address this issue in the future with forward detectors of the BM@N experiment at Nuclotron.
 

6, line 271, -> “minimum bias events were generated”

>> Response: Thank you. We corrected that.

 

7, In the caption of Fig5, need to add 10% description line similar as fig 1.

>> Response: Thank you. We corrected that. 

8, Line 298,  ‘except for”

>> Response: Thank you. We corrected that.
 

9, Line 310-317, the author commented on the central collisions discrepancy between DCM+Geant and MC-Glabuer for psd energy method, and also commented on the width between multiplicity method and psd energy method. Could author please also comment on the central value difference between these two methods, namely central value difference between Fig 7 left panel and right panel?

>> Response: Difference between centrality classes from left panel and right panel is due to the differences in the shape and width of two-dimensional distributions of impact parameter and corresponding centrality estimator.
We add a more detailed discussion of this question in the text, see Line 318.

Can we directly compare the central value for open squares between left and right?

>> Response: We should compare the centrality of events determined based on different centrality estimators and this is the part of our current work. Results will be shown in the future publications.

Also closed triangles between left and right, there are some systematic differences if we take the central value serious. How should we understand this?

>> Response: Vertical bars in the Figure 7 indicate standard deviation of impact parameter distribution of the corresponding centrality class (this is noted in the axis caption), not the systematic errors.
Width of the most peripheral 10% classes is large since the width of distributions shown on Figure 6 is large for the peripheral events.

 

Best regards,

Ilya Segal

Reviewer 3 Report

I find the draft to be well written and the work to be highly relevant. Please find my language based comments underneath:L31: "simulating large sample" --> "simulating a large sample"

L32: build --> built

L36: "for each class determined" --> "for each class are determined"

L99: "with condition" --> "with the condition"

L105: "assumed to be" --> "is assumed to be"

L150: "is very well" -->"is a very well"

L205: "Procedure" --> "The procedure"

L206: "This is following" --> "This follows"

L208: "models" --> "model"

Author Response

I find the draft to be well written and the work to be highly relevant.

>> Response: We  would like to thank the reviewer for this positive evaluation 

Please find my language based comments underneath:L31: "simulating large sample" --> "simulating a large sample"

L32: build --> built

L36: "for each class determined" --> "for each class are determined"

L99: "with condition" --> "with the condition"

L105: "assumed to be" --> "is assumed to be"

L150: "is very well" -->"is a very well"

L205: "Procedure" --> "The procedure"

L206: "This is following" --> "This follows"

L208: "models" --> "model"

>> Response: Thank you. We corrected that.

 

Best regards,

Ilya Segal

Round 2

Reviewer 2 Report

The revised version made the corrections as I suggested. I would recommend publishing the manuscript without any further delay.