On the Disintegration Products of the 2.2-μSec. Meson

Abstract

An investigation of the penetration through absorbers of various elements by the charged particles that result from the 2.2-\ensuremath{\mu}sec. meson decay is reported. Mesons and decay particles are detected by an arrangement of Geiger-M\"uller counter trays, and delayed coincidence techniques are used to select the desired events. The absorption measurements exhibit two components in the decay radiation, one of which is much more penetrating than the other. In lead, for example, the "soft component" is essentially absorbed by about 20 g/${\mathrm{cm}}^{2}$, while the "hard component" is easily detected after 38 g/${\mathrm{cm}}^{2}$.A different arrangement of counters is used to show that the "hard component" is due to a neutral radiation which accompanies the charged decay particles. This result, and measurements of the intensities of the "hard component" with lead and carbon absorbers, provide strong evidence that the neutral radiation is, in fact, bremsstrahlung from the charged particles which constitute the "soft component."The bremsstrahlung intensities, together with the form of the absorption curve, are shown to lead to the following conclusions: (1) the charged decay particles are electrons (i.e., they have a mass less than two electron masses); (2) a considerable number of electrons are emitted with energies greater than 25 Mev; (3) the average energy of the electrons is greater than 25 Mev; (4) there is no evidence for electrons of energy much greater than 50 Mev.The support which these results lend to the currently favored ideas on the meson decay process is discussed.