Agreement between the Xmax distributions measured by the Pierre - - PowerPoint PPT Presentation

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Jun 27, 2023 180 likes •458 views

Agreement between the Xmax distributions measured by the Pierre Auger and Telescope Array Observatories J. Bellido, J. Belz, S. Blaess, V. de Souza, W. Hanlon, D. Ikeda, P. Sokolsky, Y. Tsunesada, M. Unger, A. Yushkov, for the Pierre Auger

SLIDE 1

Agreement between the Xmax distributions measured by the Pierre Auger and Telescope Array Observatories

J. Bellido, J. Belz, S. Blaess, V. de Souza,
W. Hanlon, D. Ikeda, P. Sokolsky,
Y. Tsunesada, M. Unger, A. Yushkov,

for the Pierre Auger and TA Collaborations

Presenter: Vitor de Souza University of São Paulo

SLIDE 2

Take away message We present the solution for a decade-long controversy. TA and Auger composition measurements (Xmax) agree within the systematics 18.2 < log10(E/eV) < 19.0

SLIDE 3

Don’t jump into conclusions

Different detectors and analysis.

TA Collaboration, ICRC2017 Auger Collaboration, ICRC2017

SLIDE 4

Auger bias

≠

TA bias

Auger

– Xmax at the

atmosphere

– Approx. unbiased

– Xmax in the detector – Enhance statistics

Xmax ATM ≠ Xmax DET

SLIDE 5

Auger bias ≠ TA bias

SLIDE 6

How to compare Xmax from Auger and TA ?

XmaxAuger XmaxTA

Xmax always in g/cm2

N = 1953 N = 625

SLIDE 7

XmaxAuger TA Detector Simulation TA Analysis XmaxTA(Auger)

Mean = 744 RMS = 66 Mean = 738 RMS = 60

Auger Data

SLIDE 8

XmaxAuger TA Detector Simulation TA Analysis XmaxTA(AugerMix)

Mean = 738 RMS = 60

AugerMix

SAME RESULTS WITH EPOS-LHC

SLIDE 9

XmaxTA(AugerMix) XmaxTA(TAData) XmaxTA

Are these distributions compatible ? Now we can compare the distributions

TAData AugerMix

SLIDE 10

XmaxTA

TAData AugerMix

Get P1data P1 = 5.34x10-21

P1MC Distribution 105 MC realizations of AugerMix

Count (N) how many times P1MC < P1data Compatibility Probability P2 = N/105 Compatibility tests: Anderson-Darling and Kolmogorov-Smirnov Normalize P1 probabilities Get 105 P1MC probabilities

P2 < 10-5

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Xmax Systematic Uncertainty TA = 20.3 g/cm2 Auger ~ -10 and +8 g/cm2 Shift Xmax to match the mean of the distributions. Recalculate the compatibility tests.

Systematic Uncertainties

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Xmax Shift versus Systematic Uncertainties

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Compatibility between TA data and AugerMix

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Repeat the same analysis but now calculates the compatibility probability P2 between TA data and pure proton Xmax distributions.

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Comparison of TA data with AugerMix and Protons

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Conclusion

18.2 < log10(E/eV) < 19.0

TA Xmax distributions are compatible to AugerMix Xmax distributions within the systematic uncertainties.

SLIDE 19

Conclusion

18.2 < log10(E/eV) < 19.0

TA Xmax AugerMix Proton TA Xmax distributions are as compatible to pure proton composition as they are to AugerMix.

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Xmax Compatibility Table

18.2 < log10(E/eV) < 19.0

Proton

Mixed Iron

Auger Auger TA

!!!

Compatible Incompatible

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Request to the UHECR community

Proper comparison demands use of detector simulation and analysis chain of both experiments. Please refer to this common (Auger/TA) analysis in your studies. Do not propagate an unsustainable controversy.

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Extras

SLIDE 23

Compatibility tests

Kolmogorov-Smirnov and Anderson-Darling
Calculate the probability (P1data) that the two distributions

were generated from the same parent distribution

DETXmaxTA (AugerMix) versus DETXmaxTA (TAData)

Draw 105 MC distributions of DETXmaxTA (AugerMix)

– Use fit – Calculate 105 P1MC – Get P1MC distribution -> Compatibility distribution

Using the distribution P1MC calculate the probability P2 of

finding a P1 worse than P1data P2 = Compatibility Probability Gauss⊗Exponential

SLIDE 24

Comparison of TA data with AugerMix and Protons

SLIDE 25

WG - UHECR 2016

Mean Xmax Comparison

SLIDE 26

WG - ICRC 2015

Mean Xmax Comparison