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Design and Calibration of a New Apparatus to Measure the Specific Electronic Charge


Dacey, George Clement (1951) Design and Calibration of a New Apparatus to Measure the Specific Electronic Charge. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/KW0Z-FQ64.


The theory of a free electron method for measuring e/m0 is described. This method consists essentially in the use of a well defined, rotating, high-frequency magnetic field as a phasing valve to determine the velocity of an electron stream. Use of the relativistically correct energy equation then yields e/m0, if the potential of the electron stream is known. As shown below the use of a resonant cavity operating in the TM110 mode, approximately produces such a field.

The apparatus which was designed and constructed to support the cavity, maintain high-vacuum, provide radio-frequency, produce and measure the electron beam, and measure the parameter of internet is described. Included also are circuit diagram of the various control and measurement electronic circuits.

Finally, data are given which determine essentially the resolving power of the instrument. Estimates are made as to the probable ultimate accuracy of the measurement. It is shown that an accuracy of 1 part in 10,000 should be easily obtainable in a given run, and that accuracies of several parts in 100,000 should be possible with more data.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Physics and Mathematics)
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Minor Option:Mathematics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Smythe, William Ralph
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 January 1951
Funding AgencyGrant Number
Office of Naval Research (ONR)UNSPECIFIED
Record Number:CaltechTHESIS:09292017-105034713
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10468
Deposited By: Benjamin Perez
Deposited On:02 Oct 2017 14:50
Last Modified:25 Apr 2023 01:00

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