Masters Theses


"A number of physicists of recent years have been attempting to explain the basic nature of the universe in terms of particles. A few particles have been predicted theoretically, and some of these, along with many others have appeared experimentally, Searches for them have presented some interesting experimental problems and brought forth some invaluable experimental apparatus. One of these devices is the Wilson cloud chamber, with which this thesis is concerned.

Of the particles that have been discovered thus far, only the electron and the proton appear to be stable. The rest ultimately decay by the emission of photons and electrons, and possibly neutrinoes, until they reach the state of the electron or proton. The stability of the neutrino is still controversial, but its rest mass is generally accepted to be zero. It is the only particle believed to have less mass than the electron.

Another property of particles which aids greatly in describing the nature or matter is charge. Spin and magnetic moment also hold interesting possibilities, but this discussion will be confined to charge. All of the particles which are charged appear to have a charge numerically equal to that or the electron. This is somewhat difficult to prove experimentally; and, since at present there is no theoretical basis for the quantization or charge, there is reasonable room for doubt. If charge values other than integral multiples of the accepted electronic charge do exist, ionization measurements of tracks in a Wilson cloud chamber (the most sensitive of all ion detecting instruments) should expose them if their values lie within certain limits imposed by the apparatus.

There is also some theoretical basis for the possible existence of a magnetic monopole. The experimental observation of a magnetic monopole would be of considerable theoretical interest. It should be recognizable by a careful study of its ionization in a Wilson cloud chamber.

In searching for nonstandard electric charge values by ionization methods, it is necessary to avoid contusion with standard electronic charge values. Since the ionization of an electric charge passes through a minimum with increasing velocity, it would seem advisable to restrict early experiments to charge values which would produce minimum ionizations well below the minimum ionization of an electron. It is possible that other types of particles such as magnetic monopoles could produce ionization rates in the region below the minimum ionization of the electron. There is also the possibility that there are neutral particles with unusual magnetic moments which could give rise to very small ionization rates. All such particles shall be defined as subionizers.

This work, then, will be concerned with establishing the techniques and performing a preliminary search with our apparatus for any particles which ionize more lightly than the minimum ionization rate of the electron. It is expected that particles having ionization rates between one ion pair per cm of path length and fifteen ion pairs per cm can be definitely distinguished from light trails or droplets produced by poor chamber conditions. This corresponds to a sub-charge between 1/7 e and 1/2 e"--Introduction, pages 1-3.


Kassner, James L.

Committee Member(s)

Lund, Louis H., 1919-1998
Miles, Aaron J.
Johnson, Charles A.



Degree Name

M.S. in Physics


The Research Corporation


Missouri School of Mines and Metallurgy

Publication Date



iv, 51 pages

Note about bibliography

Includes bibliographical references (pages 48-50).


© 1959 Joseph B. Hughes, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Cloud chamber

Thesis Number

T 1218

Print OCLC #


Electronic OCLC #


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