CXIX. The mean lifetime and frequency of production of charged V-particles

Abstract

Data for the determination of the mean lifetime of charged V-particles are discussed, following the procedure outlined by Wilson and Butler (1952). The tracks of twenty-seven V ^±-particles have now been photographed on the Pic-du-Midi (2 867 m) by Armenteros et al. (1952) and by the authors in a circular cloud chamber, 28 cm in diameter. It is shown that, using these data, the chamber is too small for the lifetime to be determined, but a lower limit of 1·0 × 10^-10 sec is obtained. Furthermore, the relation between the frequency of production of energetic V ^±-particles in penetrating showers of average energy (10–30) Bev, and various assumed lifetimes is discussed. Using recent photographic emulsion data on the frequency of particles of mass about 1200 m_e in the same type of penetrating shower an upper limit for the lifetime of 10^-8 sec is obtained.