Atmospheric Effect on Cosmic Ray Muons at High Cut-Off Rigidity Station

Abstract

Cosmic ray data and radiosonde measurements from Riyadh, Saudi Arabia (Rc = 14.4 GV), for the period 2002–2012, were used to study the effect of atmospheric pressure, level of pion production, and temperature at that level, on cosmic ray muons. We found that, even if corrections were made to the detected muons using these three parameters, seasonal variations of the cosmic rays still exist. This suggests that other terrestrial and/or extraterrestrial causes may be considered. The levels of pion production and atmospheric pressure are inversely correlated with the muon rate. On the other hand, the temperature at the pion production level is correlated with muons in spring and winter and inversely correlated in fall and summer. There is no clear explanation for this behavior.

The Effect of Some Meteorological Parameters on the Cosmic Ray Muons detected by KACST detector

“…It can be seen that the number of cosmic ray muons is reduced as the temperature increases. This anti-correlation between the two variables is in agreement with the previously published results of several researchers [6][7]. The decrease in the muon rate as the temperature increases is due to changes in the atmospheric density, which in turn depends on atmospheric temperature.…”

“…The rate of the cosmic ray muons due to changes in a meteorological variable x, can be determined experimentally by [6][7]:…”

“…Another finding from this graph is that seasonal variations exist even when the corrections were made using different methods. This strongly suggests that information about atmospheric variables at various levels in the atmosphere may be used to remove this seasonality [7]. …”

“…At the detection level, the majority of the observed particles are muons. Their rate depends on several meteorological factors such as the atmospheric pressure, temperature, and the height of the pion production level (height of the first interaction); see for example [4][5][6][7]. Several investigations have shown that the variations in the atmospheric variables' coefficients depend on different factors, such as the type of detected particle and the cutoff rigidity of the considered site [8][9].…”

“…In order to study the properties of the primary cosmic rays and their modulations caused by the solar and heliospheric instabilities, corrections to the secondary cosmic ray particles, due to atmospheric influences, must be made as in Dorman [4] and Maghrabi and Almutayri [7] for example. The main aim of the current study is to investigate experimentally the relationship between the cosmic ray muons detected by the King Abdulaziz City for Science and Technology (KACST) detector, and the atmospheric pressure, temperature, and relative humidity, and to obtain the correction coefficients of these variables.…”