5 research outputs found
Calculation of rescaling factors and nuclear multiplication of muons in extensive air showers
Recent results obtained from leading cosmic ray experiments indicate that
simulations using LHC-tuned hadronic interaction models underestimate the
number of muons in extensive air showers compared to experimental data. This is
the so-called muon deficit problem. Determination of the muon component in the
air shower is crucial for inferring the mass of the primary particle, which is
a key ingredient in the efforts to pinpoint the sources of ultra-high energy
cosmic rays.In this paper, we present a new method to derive the muon signal in
detectors, which uses the difference between the total reconstructed (data) and
simulated signals is roughly independent of the zenith angle, but depends on
the mass of the primary cosmic ray. Such a method offers an opportunity not
only to test/calibrate the hadronic interaction models, but also to derive the
exponent, which describes an increase of the number of muons in a
shower as a function of the energy and mass of the primary cosmic ray. Detailed
simulations show a dependence of the exponent on hadronic interaction
properties, thus the determination of this parameter is important for
understanding the muon deficit problem. We validate the method by using Monte
Carlo simulations for the EPOS-LHC and QGSJetII-04 hadronic interaction models,
and showing that this method allows us to recover the ratio of the muon signal
between EPOS-LHC and QGSJetII-04 and the average exponent for the
studied system, within less than a few percent. This is a consequence of the
good recovery of the muon signal for each primary included in the analysis.Comment: This work corresponds to the presentation at the ICNFP 2022 at
Kolymbari, Crete, in September 2022. The proceedings will be published in
Physica Scripta. arXiv admin note: text overlap with arXiv:2108.0752
The role of large-scale magnetic fields in galaxy NGC 891. Can magnetic fields help to reduce the local mass-to-light ratio in the galactic outskirts?
We address the problem of the influence of large-scale magnetic fields on
galactic rotation for the example of the spiral galaxy NGC 891. Based on its
rotation curve and the surface density of HI we determine, in the framework of
the global disc model, the surface density of matter. Then, based on the
surface brightness, we determine the corresponding profile of the local
mass-to-light ratio. We also model the vertical gradient of azimuthal velocity
in the quasi-circular-orbit approximation, and compare it with measurements. We
discuss what factors may influence the rotation of matter in NGC 891 and how
this can translate to changes in the profile of the local mass-to-light ratio.
In particular, we discuss the possible effect of magnetic fields on the motion
of ionized gas, and, consequently, on the determination of the profile of the
local mass-to-light ratio. Finally, we put forward the hypothesis that the
asymmetry in magnetic fields observed in NGC 891 might be responsible for the
observed anomalous behaviour of the vertical gradient.Comment: 6 pages, 12 figure