Shape of Cosmic-Ray Star-Size Distributions in Nuclear Emulsions

The occurrence of a break in integral star-size distributions at a prong number of approximately 7, previously observed with nuclear emulsions in the lower atmosphere, has also been found at several stratosphere altitudes under a variety of conditions. This shows that the effect is due mainly to the composition of the nuclear emulsion. Although the shape of the distribution curves is thus strongly influenced by the properties of the detector, the altitude dependence of the nucleonic energy spectrum is clearly reflected in the progressive change in the slopes of these curves.