Study the correlation of muon paddle efficiency with temperature, pressure, decoherence curve and effect of multiple scattering physics in geant4 based detector simulation

The motivation behind the present study is to determine the correlation of muon count rate with the atmospheric parameters that affect the detector sensitivity. The geomagnetic cutoff rigidity i.e. 22 GeV of primary particle is computed for our muon paddle which is located at Agra, India (27.180 N and 78.020 E). The maximum solid angle of 0.15 rad is obtained for the assembly. The integral muon flux observed from analytical and experimental calculation is 9.61 / cm2.sec.str with a statistical error of ±0.31%. The differential intensity of muon at sea level obtained from calculation is 9.12x10-2 (sr-1.cm-1.sec-1. (GeV/c)-1). The count rate as function of detector separation (horizontal-vertical) is determined to project decoherence curve. The three fold efficiency of muon paddle ranges within (60-80)% over the period of 16 Dec 2014 – 24 Dec 2014. It marks the stability of muon detection. The correlation between temperature, atmospheric pressure and count rate was also analyzed for a duration of 1 Dec 2014 – 16 Dec 2015. The chi-square testing is also applied for the count rate where the p-value of the correlation coefficient is observed to be less than (0.01). To understand further the muon interactions and their phenomena in the detector, the muon paddle is simulated in Geant4.9.4.p04 toolkit. The effect of various surface treatments such as ground, etched and polished for each individual reflectors i.e. (Lumirror, Teflon, TiO2 and Tyvek) are also simulated to study the photon yield for incident muon. Among these reflectors, tyvek wrapping with a polished surface of dielectric_metal interface is observed to have a maximum of 96% photo yield is able to reach the sensitive region of the detector. The study further includes the multiple scattering phenomena to observe its effect on muon interactions in various density materials. The total cross-section and interaction length of muons are also computed relative to multiple scattering physics