Diurnal Variation of Cosmic Ray Intensity and Nova Herculis

Abstract

LAST year several articles were published describing measurements made with the intention of deciding whether the outburst of the Nova Herculis had an influence upon the intensity of cosmic radiation. The results obtained with the coincidence method are not in perfect agreement with each other: Kolhörster¹ has found, and we² have not found, a Nova effect. To clear up the question we made, from July 24 until August 5, 1935, measurements with two Geiger-Müller counters of 100 cm. effective length, and 4 cm. diameter, placed 7 cm. apart with their axes parallel to the north-south direction, one above the other. We used the Barnóthy coincidence method which makes it possible to neglect the number of chance coincidences, as they are less than 0.4 per cent of the true ones. The apparatus is provided with an automatic impulse size regulator which kept the sensibility of the counters during the whole time of measurements at a constant value, so that they were not influenced by any changes occurring in the inside temperature or in the supplying voltage. In 349 hours we registered 1.53 million coincidences; their distribution during the three periods of the day is shown in the accompanying table.