A Caltech Library Service

Cloud Chamber Study of Cosmic-Ray Particles


Kuo, I-Cheng (1941) Cloud Chamber Study of Cosmic-Ray Particles. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/A9QD-RA96.


In order to study the energy loss of cosmic-ray electrons in light materials where inelastic atomic collisions account for the main part of the loss, 10,000 cloud chamber photographs were taken in which a thin-walled copper counter or a combination of one or two counters with a 1/4 inch carbon plate was placed across the chamber as an absorber. The counter or counters was used at the same time to control the expansion. Only electrons of energy from 10 to 60 Mev are suitable for this purpose. These occur infrequently and only 36 particles in the case of a single counter absorber and 33 in the case of a counter-carbon absorber were found suitable for accurate measurement. The observed average values of energy loss in Mev/cm are compared with the theoretical average value. The result shows that in the energy range considered the theoretical formula for energy loss of electrons (no heavy tracks were included) by direct collisions are in approximate agreement with observation. The importance of an experimental test of these formulae lies in the fact that the mass estimates of the mesotron so far made have been based on the validity of these formulae.

Several heavily ionized tracks were discussed by considering their ionization and range relations. One of these was found to be probably a mesotron of negative charge. Two cases of abnormal energy loss which can not be accounted for by ionization and radiation alone were also discussed.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Physics
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Millikan, Robert Andrews
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 January 1940
Record Number:CaltechTHESIS:12052012-163755571
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7305
Deposited By: Benjamin Perez
Deposited On:06 Dec 2012 16:53
Last Modified:09 Nov 2023 23:54

Thesis Files

PDF - Final Version
See Usage Policy.


Repository Staff Only: item control page