The number of high energy electrons present in cosmic rays at sea level

Abstract

There are several problems in which the question arises of how corpuscular rays, in a layer of a given height, for example at sea level, are distributed over the various components: mesons, protons and electrons, and what is the energy they possess. We shall not here consider the protons present only in small number. But it is of some importance to know the number of primary electrons of high energy still present at sea level. Thus, to separate the hard from the soft rays and ascertain how many soft rays are still present in the total Various authors the writer was himself one of them have assumed that practically speaking no more electrons are found through 10 cm Pb, that were produced by an electron falling into the lead; or, at any rate, that their percentage is so small as to be insignificant. Further, for the determination of the length of life of the mesons it is important to know the percentage of primary electron radiation still present in a given layer. Especially in view of the application of the shower theory it is necessary to know how many high energy electrons are still present, for some writers are inclined, in regard to the theory of extensive showers, to assume the existence of energies up to any conceivable height ; i.e. 1 Cl8 evolt. In order to make an approach to the solution of this question we drew up the following disposition of counters (vide Fig. 1). A layer of 3 counters of 6 mm in diameter and 45 cm in length was circuited parallel. The counters lay on a plate under which a layer of lead A of from 0 to 20 cm could be placed. A layer of lead of from 0 to 30 cm could be fixed above the counters in question, which layer filled the entire bundle formed by these counters and the counters 2, 3, 4 and 5, which were placed below.