The Rossi Transition Curve for Small Angle Showers

Measurements have been made of 7° and 28° cosmic-ray shower production in iron up to thicknesses of approximately 320 g/${\mathrm{cm}}^2$. A comparison of the data here presented and measurements previously reported for 38° showers leads to the conclusion that there is no significant difference in the ratio of counting rates at the first maximum of the Rossi transition curve to that under 200 g/${\mathrm{cm}}^2$ for either large or small angle showers. It is concluded that the processes which are responsible for the character of the transition curve under large thicknesses of material are not necessarily restricted to small angles.