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Cloud chamber observations of cosmic rays at 4300 meters elevation and near sea-level

Anderson, Carl D. and Neddermeyer, Seth H. (1936) Cloud chamber observations of cosmic rays at 4300 meters elevation and near sea-level. Physical Review, 50 (4). pp. 263-271. ISSN 0031-899X. doi:10.1103/PhysRev.50.263.

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Cloud chamber photographs at 4300 meters elevation show positive and negative electron tracks similar to those observed at sea-level, but positive-negative electron showers occur more frequently and, in general, consist of more numerous tracks. Showers of 2-4 tracks, 5-10 tracks, and 11-100 tracks occur respectively, 8.6, 21 and 29 times as frequently per unit time at 4300 meters as they do near sea-level. Further measurements on the energy loss in lead of electrons up to 400 MEV, are given. They show that in this range of energies the energy loss in lead is roughly proportional to the incident energy. About one percent of the exposures on Pike's Peak reveal the presence of strongly ionizing particles which in most cases seem to be protons. The proportion of such tracks is considerably greater than at Pasadena. These heavy tracks in general bear only little relation in direction to that of the incoming beam, and usually arise from a type of nuclear disintegration not heretofore observed. The energies of these heavily ionizing particles may rise to values so high as 150 MEV, thus indicating that the source of the particle energies is in the cosmic rays.

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Additional Information:©1936 The American Physical Society. Received 9 June 1936. We wish to express our sincere gratitude to Professor R.A. Millikan for his unfailing support and interest in the work, and for his continual assistance in the planning of it, and the analysis of the results. Our thanks are due also to Dr. John Strong for aluminizing the mirrors used for the stereoscopic photography, and to Messrs. Lewis Browder and Thomas Harper for their able assistance in preparing the apparatus for use on Pike's Peak, and in gathering data from the photographs. It is a pleasure to thank Mr. E.E. Ewing and Mr. B. Stewart for their courtesies extended to us on Pike's Peak. We are also much indebted to the Union Oil Company of California for their kind gift of the fuel used to operate the power plant on the summit, and to the Carnegie Corporation of New York and the Carnegie Institution of Washington for allotting to Professor Millikan the major part of the funds which have made these researches possible.
Issue or Number:4
Record Number:CaltechAUTHORS:ANDpr36
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7197
Deposited By: Tony Diaz
Deposited On:17 Jan 2007
Last Modified:08 Nov 2021 20:40

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