μPPET: Investigating the Muon Puzzle with J-PET Detectors
, Kavya Valsan Eliyan 1,4, Gabriel Moskal 4,5, Nousaba Nasrin Protiti 2, Diana Laura Sirghi 3,6,7, Ermias Yitayew Beyene 1,4, Neha Chug 1,4, Catalina Curceanu 3, Eryk Czerwiński 1,4, Manish Das 1,4, Marek Gorgol 8, Jakub Hajduga 9, Sharareh Jalali 1,4, Bożena Jasińska 8, Krzysztof Kacprzak 1,4, Tevfik Kaplanoglu 1,4, Łukasz Kapłon 1,4, Kamila Kasperska 1,4, Aleksander Khreptak 1,4, Grzegorz Korcyl 1,4, Karol Kubat 1,4, Filip Lisowski 10, Szymon Niedźwiecki 1,4, Bartłomiej Rachwał 9, Ewa Łucja Stȩpień 1,4, Keyvan Tayefi Ardebili 1,4, add
Show full author list
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn the manuscript the authors present a proposal to study the muon puzzle from the point of view of the observed asymmetries in parameters for the strong interaction cross-section and trajectory of the outgoing particle due to projectile-target polarizations. For this, the authors propose to use a Positron Emission Tomography detectors developed at Jagiellonian University in Krakow, Poland (muPPET) to study what they called the distribution of the muon trajectories which are related with the angular resolution of the proposed detector.
The novelty of the proposal is high enough which may be of interest for the community, but before considering for publication some comments would need to be addressed thought.
Major comments
- The general presentation of the written needs to be improved and proofread in detail. Many sentences lacks of coherence and linked between each others which makes difficult for the reader to follow up the main idea in each section. Specially in sections 1 and 3 (introduction and methodology).
- I suggest to include a brief discussion about another alternatives that have been under consideration to explain the muon excess at ground level or even at underground, see for instance S. Acharya et al JCAP04(2025)009 DOI 10.1088/1475-7516/2025/04/009 and Journal of High Energy Astrophysics 34 (2022) 19–32 DOI 10.1016/j.jheap.2022.03.004. This will highlight the potential of the authors proposal with respect to another hypothesis.
- Regarding the fitting mentioned in section 3. The quality of the fit is not discussed along the text. What is the Chi2/NDF for both fits? Is low enough to make a strong argument on the required angular resolution for this study? What is the justification to choose a Breit-Wigner distribution against a gaussian one? A discussion about the definition of the hit will be desirable to understand the difference between the simulated angle and the reconstructed one. The width of the distributions shown in Figure 4 may have a dependence on the hit definition.
- The conclusion is not strong enough regarding the stated angular resolution. It is not transparent to follow up where did the “1 degree” came from. This should be explained in more clear way. What is the needed angular resolution of the proposed detector? Is there a way to make an estimation from Monte Carlo?
Minor comments
See the PDF in the attachment.
Comments for author File: 
Comments.pdf
The english needs to be improved. A detailed proofread is suggested.
Author Response
We sincerely thank the reviewer for the detailed and constructive feedback. The comments significantly contributed to improving the clarity and structure of the manuscript. We are particularly grateful for the reviewer’s impressive work on the language, which greatly enhanced our presentation.
«The general presentation of the written needs to be improved and proofread in detail. Many sentences lacks of coherence and linked between each others which makes difficult for the reader to follow up the main idea in each section. Specially in sections 1 and 3 (introduction and methodology).»
We thank the reviewer one more time for the thorough revision of the language. We revised the manuscript thoroughly, implementing all language and clarity suggestions. Several sections were restructured and rewritten to improve coherence and flow. Regarding the title, we prefer to retain the project name, as this is the first article related to it. However, if the reviewer strongly recommends a change, we are open to further discussion.
«I suggest to include a brief discussion about another alternatives that have been under consideration to explain the muon excess at ground level or even at underground, see for instance S. Acharya et al JCAP04(2025)009 DOI 10.1088/1475-7516/2025/04/009 and Journal of High Energy Astrophysics 34 (2022) 19–32 DOI 10.1016/j.jheap.2022.03.004. This will highlight the potential of the authors proposal with respect to another hypothesis.»
We modified the second-to-last paragraph following this suggestion and clarified the potential of this hypothesis. We also include the citations in the list of citations when the muon puzzle and its possible solutions are presented.
«Regarding the fitting mentioned in section 3. The quality of the fit is not discussed along the text. What is the Chi2/NDF for both fits? Is low enough to make a strong argument on the required angular resolution for this study? What is the justification to choose a Breit-Wigner distribution against a gaussian one? A discussion about the definition of the hit will be desirable to understand the difference between the simulated angle and the reconstructed one. The width of the distributions shown in Figure 4 may have a dependence on the hit definition.
The conclusion is not strong enough regarding the stated angular resolution. It is not transparent to follow up where did the “1 degree” came from. This should be explained in more clear way. What is the needed angular resolution of the proposed detector? Is there a way to make an estimation from Monte Carlo?»
We introduced the Chi2/NDF and the parameter uncertainties in the plots. We also mentioned “why the Breit-Wigner”: the geometry of the problem is a clear example of a Cauchy distribution, hence no Gaussian.
Concerning the needed angular resolution, as stated in lines 213-215 (ref., old PDF), it is impossible to know at this stage: a full shower development to estimate the proper statistical distribution of the muon trajectory is needed. Without the hypothesis implemented, no one can tell. Nobody has ever introduced this hypothesis to any model. Therefore, there are no possible simulations that can tell us this information. It is the nature of this project to introduce the model and measure it simultaneously. That’s why, as stated in lines 215-128 (ref., old PDF), we need to improve it as much as possible.
We specified better how the angular resolution is obtained: we consider the JPET algorithm of the position reconstruction used by the J-PET for the first and the last scintillator triggered. Since the geometrical problem demands a Cauchy distribution, there is not σ, but Γ. However, the Γ can be translated as a Gaussian-like σ using the distribution areas. And the relation is simply σ = Γ/2.355. I hope this explanation can add strength to the 1°. But we would like to stress that this is the worst angular resolution we can achieve. We are confident to do better with a thorough analysis.
Reviewer 2 Report
Comments and Suggestions for AuthorsµPPET: investigating the Muon Puzzle with J-PET detectors
summary:
The authors describe the proposed measurement of muon directions from Cosmic Ray Extended Air Showers events and present the motivation for such an experiment:
- the motivation combines knowledge of general features of High Energy Cosmis Ray events with the specific detailed knowledge of spin dependent particle scattering.
- the justification to limit the energy window of Cosmic Ray events is very convincing and gives additional weight to the proposal. (ln. 99-108)
---
remarks:
line 52:
a more detailed explanation of the definition of $X_max$ could be helpful, as following the citation [5] does not directly give a definition, but assumes it as known.
line 71-73:
since X_max itself is not defined, it would help to show, how and in which sense it is coherent (between Monte Carlos? in energy ranges? ...)
lines 74-77:
The first part of the sentence is somewhat a logically formulated: how can an "outcome" of "something missing" be evident?
it can be evident, that something is missing,
it can be evident, that and outcome is missing, indicating that the phenomenon is not there ...
line 76: "it cumulates" maybe better "it accumulates" ?
line 78: "shows" -> "show" (as it is plural)
line 78-80:
a missing phenomenon cannot show evidence.
line 176:
maybe a citation of the experiments using this method could help to justify the "well-known technique"
line 182-183:
the explanation in the parentheses should be either given as being relevant in the modelling of the reconstruction of the extended air shower or left out: what is the difference between the distance "normally" measured (like on google maps) and "calculated using the geodesic distance formula, accounting for the Earth’s curvature"?
line 125: what is the meaning of the "?" as an exponent?
caption of Figure 4: it would be good to indicate that the displayed distributions come from a Monte Carlo simulation.
ln 244: a link to the publication is possible as <https://inspirehep.net/literature/469835>
Author Response
We sincerely thank the reviewer for the thorough and constructive suggestions. The remarks were extremely helpful in improving the clarity and precision of our manuscript.
The other reviewer requested a detailed language revision. We took this opportunity to clarify and improve several parts of the manuscript. We apologize if the revised version differs from the previous one, and the referring lines do not directly align with earlier corrections.
«line 52:
a more detailed explanation of the definition of $X_max$ could be helpful, as following the citation [5] does not directly give a definition, but assumes it as known.»
Lines 50-52 (ref., old PDF) define Xmax. However, to address the potential confusion noted by the reviewer, we rephrased this part for improved clarity.
«line 71-73:
since X_max itself is not defined, it would help to show, how and in which sense it is coherent (between Monte Carlos? in energy ranges? ...)»
We replaced “coherent” with “consistent” and clarified that this consistency refers to agreement between experimental measurements and Monte Carlo simulations. We also re-cited [6], which provides a comprehensive summary of relevant studies.
«lines 74-77:
The first part of the sentence is somewhat a logically formulated: how can an "outcome" of "something missing" be evident?
it can be evident, that something is missing,
it can be evident, that and outcome is missing, indicating that the phenomenon is not there ... »
We appreciate this observation. Our original intention was to refer to ‘missing phenomena’ in the models. To avoid ambiguity, we replaced “missing” with “unknown.”
«line 76: "it cumulates" maybe better "it accumulates" ?»
Corrected as suggested.
«line 78: "shows" -> "show" (as it is plural)»
Thank you for catching this. Corrected.
«line 78-80:
a missing phenomenon cannot show evidence.»
As above, “missing” was replaced with “unknown” for clarity.
«line 176:
maybe a citation of the experiments using this method could help to justify the "well-known technique”»
We added citations to AugerPrime and IceTop as examples of experiments using this technique.
«line 182-183:
the explanation in the parentheses should be either given as being relevant in the modelling of the reconstruction of the extended air shower or left out: what is the difference between the distance "normally" measured (like on google maps) and "calculated using the geodesic distance formula, accounting for the Earth’s curvature”?»
We decided to remove the explanation, as it did not contribute meaningful information to the manuscript, as the reviewer rightly pointed out.
«line 125: what is the meaning of the "?" as an exponent?»
We apologize, but we could not locate any instance of a “?” used as an exponent. We double-checked both the LaTeX source and the uploaded PDF for possible formatting issues. If the reviewer could specify the sentence in question, we would be happy to address it in the next revision or during final proofreading.
«caption of Figure 4: it would be good to indicate that the displayed distributions come from a Monte Carlo simulation. »
Corrected as suggested.
«ln 244: a link to the publication is possible as <https://inspirehep.net/literature/469835>»
hank you for the suggestion. The link has been added.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsI have not further comments. The authors nicely addressed all my previous comments/suggestions. Looking forward to read the forthcoming results with the planned data taking.
