Neutral Decay Products of Cosmic Radiation at Great Depth

Abstract

The absorption curve of cosmic radiation was measured during a period of seven years in a coal mine at a depth of about 1000 m w.e. The shape of the curve and the counter-efficiency measurements suggest that the most penetrating component of cosmic radiation consists of non-ionizing or scarcely ionizing rays. It was found that the intensity decreases for inclined directions less than it would correspond to the thickness of the material and its temperature coefficient is positive. All these experimental evidences, together with the known fact that at 400 m w.e. depth the exponent in the intensity versus depth variation changes from 1.8 to 2.8, favor the view that the radiation present at 1000 m w.e. depth is formed at the decay of the mesons in the atmosphere. Neutrini or neutral mesons may account for the findings.