Intermittency in cosmic ray showers and its possible consequences

15 maja 2024 roku o godzinie 13:15 w sali 143 odbędzie się seminarium Instytutu Fizyki, na którym
Prof. Tadeusz Wibig z Wydziału Fizyki i Informatyki Stosowanej Uniwersytetu Łódzkiego
wygłosi referat pt.: „Intermittency in cosmic ray showers and its possible consequences”.

Abstract:
In the simulation calculations that form the basis for interpreting data
from EAS arrays at higher primary particle energies, we are dealing
with millions of particles passing through the atmosphere.
In order to speed up the calculations or to make them generally feasible,
the 'thinning’ method has been used for about half a century.
This method consists in eliminating a fraction of the particles
from the cascade and in assigning an appropriate statistical weight
to the remaining particles. Such an approach is perfectly correct
if we are dealing with average images of showers, but it cannot describe
the fluctuations in the number of particles measured by any particular
single detector. The standard approach is to assume that the particles
in a shower reach the ground independently. Their numbers are assumed
to fluctuate poissonically. This approximation does not allow a correct
interpretation of the results of measurements of very small showers.
It is also not entirely correct at higher energies, especially in detectors
far from the shower axis where particle densities are low.
The question is whether the assumption that the particles in the shower
are independent leads to systematic biases in the interpretation of
the shower data.
Using accurate simulations, we found the magnitude of the particle correlations
and showed that a negative binomial distribution better describes
these distributions.
By modifying the procedures for determining shower parameters, we have shown
that changing the multiplicity statistics can change the estimated
shower sizes by up to a few percent.