Cloud-Chamber Observations of the New Unstable Cosmic-Ray Particles

Abstract

Thirty-four "forked tracks" similar to two previously reported by Rochester and Butler have been observed in 11,000 cloud-chamber photographs of cosmic-ray penetrating showers, confirming their conclusion that new unstable neutral and charged particles exist. The lifetime of the neutral particles is found to be about 3X10 -10 sec, and some information as to the nature of the decay products is given.

Masses of Identified Positive Heavy Mesons

“…2 , K!J. 3 , and K 133 • Thus, if this scheme is correct~ the primaries of all decay modes in this experiment are the same particle (hence no primary mass differences).…”

On the Production of Mesons by Primary Cosmic Rays

“…40 These results have been confirmed by the most recent cloud-chamber observations. 41 In 11,000 tracks of penetrating showers 30 pairs produced by neutral particles were found. None of the charged particles showed the properties of electrons on traversing a lead plate.…”

Low-Momentum End of the Spectra of Heavy Primary Cosmic Rays

“…R ECENT investigations [1][2][3][4][5] of the dependence of cosmic-ray intensity at high altitude upon geomagnetic latitude make it abundantly clear that there occurs a marked and rapid change in form of the integral number-magnetic rigidity spectrum of the primary radiation at a rigidity R (momentum-to-charge ratio pc/Ze) of about 1.5 X10 9 volts. In particular, 4 there appears to be a complete or nearly complete absence of primary protons in the magnetic rigidity range 1.2X10 9 volts to 0.18X10 9 volts (kinetic energy range 590 Mev to 18 Mev), and of primary alpha particles in the magnetic rigidity range 1.2X10 9 volts to 0.37X10 9 volts (kinetic energy range 700 Mev to 72 Mev).…”