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SUMMARY:Cosmic Ray Mass Composition Problem: towards model-independent eva
 luation based on the analysis of the spatial and temporal structure of EAS
  charged components
DTSTART;VALUE=DATE-TIME:20210609T072500Z
DTEND;VALUE=DATE-TIME:20210609T075000Z
DTSTAMP;VALUE=DATE-TIME:20261011T211559Z
UID:indico-contribution-147@indico.nevod.mephi.ru
DESCRIPTION:Speakers: Roman Raikin (Altai State Univesrity)\nThe determina
 tion of the mass composition of primary cosmic rays is at present stage th
 e crucial issue for understanding their origin and propagation through the
  interstellar medium. The mass composition above $10^{14}$ eV is inferred 
 from the extensive air shower (EAS) observations by comparisons with simul
 ations results\, which rely on accurate description of air shower physics 
 including hadronic interaction models uncertain in the relevant energy ran
 ge. Numerous methods and techniques are implemented\, including analysis o
 f mean values\, fluctuations\, correlations or even particular features of
  distributions of different observables characterized both longitudinal an
 d spatial shower development (depth of maximum\, muon production depth\, t
 otal number of electrons and muons at the observation level and their loca
 l densities at various distances from the shower axis\, particles arrival 
 time profiles\, spatial distributions of radio emission and Cherenkov ligh
 t etc.). Large efforts have been made recently in both gaining experimenta
 l data with increased resolution in detection of various EAS components an
 d developing improved methods for physical interpretation of the data alon
 g with evolving hadronic interaction models after the LHC results. Neverth
 eless\, the composition results still remain ambiguous in the entire energ
 y range available for EAS studies.\n\nThe discrepancies between estimates 
 of mass composition derived by various methods from the data of different 
 experiments\, in addition to insufficiency in statistics\, are apparently 
 caused by complex of instrumental and methodological systematic biases of 
 different nature\, as well as by strong model dependence of the observable
 s\, mostly in case of muon component characteristics (so-called “Muon Pu
 zzle”)\, disadvantages in taking into account meteorological effects etc
 .\n\nA possible solution might be achieved with refined (multi-)hybrid mea
 surements together with generalizations of the analysis by revealing unive
 rsal features\, based on the intrinsic physic properties of air showers\, 
 evaluation of new parameters and functionals\, which are weakly sensitive 
 to the hadronic interaction model being good primary mass indicators.\n\nI
 n this paper we present the updated analysis of spatial distributions of e
 lectrons and muons with respect to the scale invariance in lateral distrib
 ution (LD) functions (the extended scaling formalism). We demonstrate that
  this formalism enables accurate description of lateral distributions of e
 lectrons and muons by one-parametric scale-invariant functions in wide pri
 mary energy and radial distance ranges. The scale-invariance of LD and air
  shower universality manifesting through the functional dependence between
  radial scale factors and longitudinal shower age are both insensitive to 
 hadronic interaction models. An additional composition sensitive observabl
 e\, which can be included in the multicomponent analysis of experimental d
 ata obtained by 100% duty cycle ground-based detectors\, is time profile o
 f charged particles measured by surface scintillation counters at differen
 t ranges of radial distances.\n\nThus\, integrated spatial and temporal ch
 aracteristics of the charged EAS component can be effectively used as a so
 urce of the improved cosmic ray mass composition results when interpreting
  the experimental data of the ground-based EAS arrays. The proposed approa
 ch could be implemented for the present and future (multi-)hybrid air show
 er observations by TAIGA\, Yakutsk Complex Air Shower Array\, Auger and Te
 lescope Array observatories taking into account their upcoming upgrades\, 
 as well as for re-analysis and cross-calibration of the data collected fro
 m different air shower arrays within the single method in a broad primary 
 energy range.\n\nhttps://indico.nevod.mephi.ru/event/6/contributions/147/
LOCATION:Online Zoom
URL:https://indico.nevod.mephi.ru/event/6/contributions/147/
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