Coincidence Counter Studies of the Variation of Intensities of Cosmic-Ray Showers and Vertical Rays with Barometric Pressure

Abstract
Using three Geiger-Müller counters in triangular arrangement below a lead plate 1.2 cm thick, cosmic-ray shower intensities at sea level were found to diminish with increasing barometer by the factor 0.00542±0.00027 per mm mercury, corresponding to an exponential absorption coefficient of 0.41 per meter of water. Vertical rays measured with three counters in line showed a barometer effect of 0.00362±0.00044 per mm mercury or 0.28 per meter of water. The showers are thus more sensitive to barometric changes than the total cosmic radiation as had been found by experiments at different elevations.