The Variation of Penetrating Radiation with Zenith Distance

Abstract

FROM the few investigations¹ so far made of the angular distribution from the zenith of penetrating radiation, the only definite result which emerges is that the intensity is much greater in the vertical direction than in any other. Very recently Mr. Medicus has published ² the results of observations made by a method similar to mine described below. But the number of coincidences registered in the different directions is perhaps insufficient for a definite deduction. There is therefore a great need for a trustworthy series of measurements, made with an apparatus having sufficient resolving power to allow the true distribution to be deduced. An exact knowledge of this distribution is of no little importance. In the first place, it is a necessary element in the exact discussion of many other experiments. Secondly, it is interesting to see whether the observed zenithal distribution can be due to the absorption by the atmosphere of a radiation which was originally isotropic.