A Cloud-Chamber Study of Cosmic-Ray Nuclear Interactions at 3260 Meters Elevation

Abstract

In 4949 photographs of cosmic-ray phenomena, not associated with dense air showers, occurring in a counter controlled cloud chamber surrounded by lead, the numbers of nuclear interactions in which secondaries were produced and observed to occur in and above the chamber were 182 and 223, respectively. The mean free path for nuclear interaction of the penetrating particles produced in these nuclear interactions is 316=fc70 g/cm 2 of lead, while for nuclear scattering (large angle scattering without the production of secondaries) it is at least 4 or 5 times this value. The projected zenith angular distributions of the secondaries from these interactions are given. The lightly ionizing secondaries going in the forward direction have an angular distribution ^cos 3 0, while those in the backward direction from nuclear interactions occurring in the chamber have a uniform distribution.

Announcement: Publication Charge for Letters to the Editor

“…This conclusion is in agreement with the results of other workers. [4][5][6][7][8][9] However, our results do not allow us to make a definite statement on the value of the nuclear interaction length in lead of the 7r-mesons. Our arrangement is not sensitive to small-angle scattering with a small energy transfer to the lead nucleus.…”

Effects of Departures from the Single Particle Model on Nuclear Magnetic Moments

“…There have been many cloudchamber studies of these events at various altitudes and issuing from a wide variety of materials. [1][2][3][4][5][6][7][8][9][10][11] similar to the somewhat less explicit work of Davidson. 8 Although some arguments were given in favor of our rule for the formation of the many-particle configuration stated above, this rule should still be considered as somewhat arbitrary.…”