Investigation of Electromagnetic and Muonic Air-Shower Components using IceTop Simulations

Dennis Soldin (for the IceCube Collaboration); Fahim Varsi; Lincoln Draper

REVIEW 4 major objections 2 minor 1 references

Investigation of Electromagnetic and Muonic Air-Shower Components using IceTop Simulations

T0 review · 4 major / 2 minor · reviewed 2026-08-05 · deepseek-v4-flash

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Pith's one-line read The paper establishes that the two-component LDF reconstruction reproduces the muon distribution in IceTop simulations, and that the reconstructed muonic LDF parameters shift significantly with the hadronic interaction model.

desk verdict Simulation validation of IceTop's two-component LDF reconstruction; plausible but unverifiable from the corrupted full text, and the accuracy claim depends on template identifiability and truth being independent of the fit family. read the letter →

arxiv 2508.08478 v1 pith:P4EKFXN7 submitted 2025-08-11 astro-ph.HE

Lincoln Draper , Fahim Varsi , Dennis Soldin (for the IceCube Collaboration) This is my paper · ORCID

classification astro-ph.HE

keywords airshowersmuonlateraldistributionfunctionIceTophadronicinteractionmodelscosmic-raycompositionelectromagneticcomponentdetectorsimulation

verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper asks whether a surface detector array like IceTop can see the muon part of an air shower separately from the overwhelming electromagnetic part. It argues yes: by fitting two lateral distribution functions at once—one for each component—the muon distribution can be recreated in simulated showers. It then shows the reconstructed muon parameters are not fixed by the data alone; they move noticeably with the hadronic interaction model assumed in the simulation. That matters because muon measurements are a primary window into cosmic-ray composition and hadronic physics, and any model dependence must be carried as a systematic if these reconstructed parameters are used as observables.

What carries the argument

The lateral distribution function (LDF)—the expected signal density in a tank as a function of perpendicular distance from the shower axis—is the central object. The reconstruction fits two LDFs at once to the same set of tank signals: one for the electromagnetic component and one for the muonic component. The argument rests on these two templates being distinguishable in the summed signal, so the fit can assign each tank's signal to the correct component; the muonic LDF parameters are then read off from the fitted template.

What would settle it

Using simulations with Monte Carlo truth for the muon contribution in each tank, systematically reduce the muon signal and refit; if the reconstructed muonic LDF normalization fails to track the true muon fraction, or if removing the muon component leaves the muonic fit parameters essentially unchanged, the claimed accuracy of the two-component reconstruction is not established.

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Extended reading notes

Core claim

The central claim is that a simultaneous fit of separate electromagnetic and muonic lateral distribution functions to IceTop tank signals can accurately recreate the muon distribution of an air shower as seen by the array. This is established in simulation: showers are generated, tank signals are simulated, and the two-template fit is shown to recover the muon component. The paper then shows that the parameters of the reconstructed muonic LDF—its normalization and shape—change substantially when different hadronic interaction models are used to generate the same observable conditions, so the model choice is a real source of systematic uncertainty in the reconstructed muon component.

Load-bearing premise

The two component templates are identifiable in each shower: the muon signal is large enough, and its lateral shape different enough from the electromagnetic shape at the fitted distances, that the simultaneous fit returns the true muon component rather than a trade-off between the templates.

Editorial extensions

If this is right

If the two-component reconstruction is accurate, IceTop can supply per-event muon lateral distributions at GeV energies without requiring in-ice muon measurements.
Any composition or hadronic-physics result derived from the reconstructed muonic LDF must attach a systematic uncertainty reflecting the observed across-model spread of the muonic LDF parameters.
The electromagnetic LDF reconstructed in the same fit should be correspondingly cleaner for studies of the electromagnetic shower size.
Muonic LDF parameters and their model spread can be used as inputs to combined IceTop–IceCube analyses, where high-energy muons measured in the deep detector anchor the GeV muon component.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

An implication the paper leaves implicit: applied to data, the same two-component fit would let IceTop alone tag the muon content of individual showers, but only if the detector simulation's absolute signal scale matches data; a dedicated data/MC calibration would be needed.
The spread in reconstructed parameters across hadronic models is itself a handle: at energies where IceTop is sensitive, the measured muonic LDF could be compared with each model's prediction to discriminate between hadronic models.
Because the two LDF templates are fitted simultaneously, strong event-by-event shower fluctuations could push the fit into a degeneracy band; a useful stress test would be fitting with one template removed and checking how much the reconstructed electromagnetic result moves.

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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Desk Editor's Note

read the letter

Colleague,

Quick take on 2508.08478. The abstract claims two things: the two-component LDF reconstruction recreates the muon distribution accurately in IceTop simulations, and the reconstructed muonic LDF parameters shift significantly with the hadronic interaction model. Both are plausible and standard for the field, but the submitted full text is encoding-corrupted to the point of unreadability, so the load-bearing details cannot be checked.

What's actually new: not much on the abstract's own terms. The reconstruction scheme is described as the existing event-by-event approach; the paper is a validation and a hadronic-model systematic scan. That is still useful. IceTop is the only large surface array at the South Pole, and a quantified model spread on the reconstructed muon component would help composition and muon-deficit analyses.

What I can't verify: the quantitative accuracy claim. The abstract gives no numbers, no comparison of reconstructed vs. true muon densities, no error bars. The stress-test concern is legitimate and directly on point: if the simulated 'true' muon LDF is generated with the same functional family the fit uses, the agreement partly reflects template-prior recovery, not identifiability in the tank signals. The muonic signal is a small fraction of the EM-dominated signal at IceTop spacings, so an unconstrained two-template fit can trade normalization and slope. That doesn't mean the paper is wrong; it means the referee needs to see the definition of the simulation truth, the fit constraints, and the separability checks. The corrupted text hides exactly that.

The hadronic-model scan is a mild circularity: if the fit follows its template prior, the model spread may reflect the templates. But even then, a quantified shift across generators is a useful systematic envelope, provided the shift is presented with uncertainties. Also, the corrupted source contains an embedded arXiv header from a different paper (2508.08479 cs.DC), which suggests the wrong file was submitted.

Bottom line: this is a workmanlike validation study, not a new discovery. It deserves a full peer review because IceTop muon reconstruction is central to current composition work, and the paper could supply the missing systematic. My verdict is conditional on the referee being able to read the full text. Tell the authors to resubmit a clean PDF.

I would not cite it until the details are visible, but I'd send it to an expert referee.

Referee Report

4 major / 2 minor

Summary. The manuscript presents a simulation-based study of IceTop air-shower reconstruction, in which electromagnetic and muonic lateral distribution functions (LDFs) are fitted simultaneously to tank signals on an event-by-event basis. The abstract claims that this two-component reconstruction accurately reproduces the muon distribution and that the reconstructed muonic LDF parameters vary significantly with the hadronic interaction model. However, the submitted full text is almost entirely unreadable, consisting of replacement characters with only the abstract and scattered equation fragments legible. No quantitative validation, no concrete definition of the LDFs or fit constraints, and no description of the simulation truth can be verified from the supplied material.

Significance. If the method and validation were fully supported, this work could be valuable for IceCube/IceTop cosmic-ray composition studies and for quantifying hadronic-model systematic uncertainties in surface-detector muon measurements. The paper does not ship machine-checked proofs, reproducible code, or a publicly accessible derivation; the contribution is currently unsubstantiated because the readable portion contains no quantitative accuracy metric, no uncertainty analysis, and no independent cross-check of the muon reconstruction.

major comments (4)

[Abstract / Full Text] The central claim that the two-component LDF reconstruction 'recreates the muon distribution in IceTop accurately' is not supported by any quantitative metric in the readable text. The manuscript must provide, at minimum, reconstructed-versus-true muon densities, bias and resolution as a function of energy and distance, and uncertainties on the reconstructed LDF parameters. Without these, the accuracy claim is unverifiable and load-bearing.
[Full Text (unreadable)] The submitted full text is corrupted and unreadable; sections, equations, figures, and tables cannot be inspected. This makes it impossible to check the definitions of the electromagnetic and muonic LDF templates, the exact fitting procedure, the constraints used, or the nature of the simulation truth. A clean, readable manuscript is required before any substantive evaluation can proceed.
[Validation / ground truth] The stress-test concern about circularity is not resolved. If the 'true' muon LDF used for validation is generated from the same functional family and with the same parameterization as the muonic template fitted to the tank signals, then a good fit may only show template-prior recovery rather than genuine identifiability of the GeV muon component. The authors must demonstrate that the ground-truth muon distribution comes from an independent source, e.g., particle-level simulation output or a distinctly parameterized LDF, and that this independence is maintained in the closure tests.
[Identifiability of the two-component fit] The physical regime makes identifiability nontrivial: the muonic signal is a small fraction of the electromagnetic signal at IceTop spacings, and an unconstrained two-template fit can trade normalization and slope between the components. The paper needs explicit identifiability checks, such as profile-likelihood scans, covariance analysis, or closure tests with injected muon components whose LDF shape differs from the template family. Without this, the reported shift of muonic parameters with hadronic model may reflect template degeneracy rather than a physical hadronic-model dependence.

minor comments (2)

[References / context] No readable references are present in the submitted text, so the relationship to previous IceTop muon-reconstruction and LDF-fitting work cannot be assessed. The authors should ensure the bibliography is complete and properly rendered.
[Figures and tables] The figure and table captions appear garbled, making it impossible to interpret even the fragments that are visible. All figures and tables must be legible and properly captioned in the revised version.

Circularity Check

0 steps flagged · score 0.0 of 10

No circularity established from the available readable text; the simulation-truth validation is materially independent of the reconstruction.

full rationale

The only fully readable portion of the manuscript is the abstract, which states that the electromagnetic and muonic components are reconstructed by simultaneously fitting separate lateral distribution functions, and that the reconstruction is demonstrated to recreate the muon distribution accurately. No equations, definitions, fit details, or cited prior results are readable in the supplied full text, so I cannot exhibit any specific step where an output is identical to an input by construction. The abstract's central accuracy claim is validated against simulated ground truth, which is structurally independent of the fitting procedure unless the truth is generated by the same LDF family used in the fit, but no such identity can be quoted from the readable text. The secondary observation that reconstructed muonic-LDF parameters vary with hadronic interaction model is a dependence statement, not a derivation that reduces to its own inputs; it is an expected physical consequence and does not by itself constitute circularity. Without quotable evidence of a self-definitional fit, a fitted input renamed as a prediction, or a load-bearing self-citation chain, the appropriate finding under the hard rules is no significant circularity.

Assumptions & free parameters 2 free parameters · 4 assumptions · 0 invented entities

All entries are inferred from the abstract because the full text was unreadable. The central claim rests on two empirical LDF templates with fitted parameters, a simulation chain that supplies ground truth, and the statistical identifiability of the two components; none of these are supplied by the paper itself.

free parameters (2)

Electromagnetic LDF normalization and shape parameters
Per-event fitted parameters of the EM lateral distribution template; the functional form is chosen upstream and constrains what the fit can recover. Specific values are not visible in the abstract.
Muonic LDF normalization and shape parameters
Per-event fitted parameters of the muon lateral distribution template; their values are the reported subject of the hadronic-model dependence study. The template family itself is a modeling choice on which the accuracy claim depends.

assumptions (4)

domain assumption Monte Carlo air-shower generators with their hadronic interaction models represent the true muon production in PeV showers.
The validation is performed using IceTop simulations (abstract), so the simulation chain is the ground truth for the accuracy claim.
domain assumption The IceTop detector simulation faithfully converts EM and GeV-muon energy deposits into the tank signals the fitter receives.
If detector response is mis-modeled, a reconstruction that works on simulated tanks may not transfer to data; the abstract offers no data cross-check.
domain assumption The muonic and electromagnetic LDF template families are identifiable in a simultaneous per-event fit.
The claim that the muon distribution is recreated accurately presupposes that the muon component is separable from the dominant EM component at the fitted distances.
domain assumption The hadronic interaction models compared bracket the plausible physical range of muon yield.
The model-dependence study is interpreted as a systematic sensitivity only if the chosen models span a physical range; standard framing in the field.

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Cite this review

Pith. "Pith review of Investigation of Electromagnetic and Muonic Air-Shower Components using IceTop Simulations." pith.science (2026). https://pith.science/paper/P4EKFXN7

@misc{pith2026250808478,
  author       = {Pith},
  title        = {Pith review of: Investigation of Electromagnetic and Muonic Air-Shower Components using IceTop Simulations},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/P4EKFXN7}},
  note         = {Machine review of arXiv:2508.08478}
}

abstract

The IceCube Neutrino Observatory studies cosmic-ray initiated extensive air showers (EASs) using the IceTop surface array, which is sensitive to the electromagnetic component and low-energy ($\sim$ GeV) muonic component of EASs. The contribution from the two components is reconstructed on an event-by-event basis by simultaneously fitting separate lateral distribution functions (LDFs) for both the electromagnetic and muonic components of each shower. In this work, we demonstrate the ability of the two-component LDF reconstruction to recreate the muon distribution in IceTop accurately. The parameters characterizing the reconstructed muonic LDF can vary significantly based on the choice of hadronic interaction model. Thus, the dependence of the reconstructed muon LDF and other parameters on the hadronic interaction models is investigated.

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