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World Forum
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Seasonal variations in the intensity of muon bundles detected at the ground level

Jul 30, 2015, 3:30 PM
1h
Amazon Foyer (World Forum)

Amazon Foyer

World Forum

Churchillplein 10 2517 JW Den Haag The Netherlands
Board: 231
Poster contribution CR-EX Poster 1 CR

Speaker

Prof. Rostislav Kokoulin (National Research Nuclear University MEPhI (Moscow Engineering Physics Institute))

Description

Experimental data accumulated in a 3-year long series of measurements (from May 2012 to April 2015) of cosmic ray muon bundles with the coordinate-tracking detector DECOR are analyzed. It has been found that the measured rate of the events exhibits clear seasonal variations, repeated every year of observations. The amplitude of the first annual harmonic of the event rate has been estimated as (5.7 +/- 0.1) % with the maximal intensity in January, and the minimal one in July. Thus, the difference between the average intensity of muon bundles recorded in winter and in summer exceeds 10 %. Taking into account that the mean energy of muons registered in the bundles is of the order of several tens GeV, the observed difference cannot be described in frame of a well-known mechanism of the formation of the temperature effect due to decays of low energy particles in the atmosphere, which is typical for single muons detected at the ground level. An alternative explanation related with changes of the shape of the lateral distribution function of EAS muons in the atmosphere with a variable temperature profile is discussed.
Registration number following "ICRC2015-I/" 46
Collaboration -- not specified --

Primary author

Prof. Rostislav Kokoulin (National Research Nuclear University MEPhI (Moscow Engineering Physics Institute))

Co-authors

Dr Alexey Bogdanov (National Research Nuclear University MEPhI (Moscow Engineering Physics Institute)) Dr Anna Dmitrieva (National Research Nuclear University MEPhI (Moscow Engineering Physics Institute)) Mrs Ekaterina Kovylyaeva (National Research Nuclear University MEPhI (Moscow Engineering Physics Institute)) Mrs Evgeniya Romanenkova (National Research Nuclear University MEPhI (Moscow Engineering Physics Institute)) Dr Victor Shutenko (National Research Nuclear University MEPhI (Moscow Engineering Physics Institute))

Presentation materials