A number of theories which invoke a general magnetic field in the Galaxy have been proposed in the last ten years, but until recently no attempt has been made to measure the force or flux-density of this field directly. Two separate attempts have been made to measure the magnetic flux-density in five different regions of the Galaxy with the inverse Zeeman effect of hyperfine-structure on the 21-cm hydrogen line. A search was made for circularly polarized radiation on the line edge following a suggestion of Bolton and Wild. The difference in power received between the two opposite senses of polarization was recorded continuously as the receiver scanned in frequency across the line. In the first attempt which is described in Chapter 2, a special receiver and primary-feed were designed, constructed and used with the 250 ft. radio-telescope. The narrow deep Orion-arm absorption-feature in Cassiopeia-A was studied and an upper limit of 5 x la-5 gauss was set on the radial component of flux-density in the absorbing region.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:616280 |
| Date | January 1961 |
| Creators | Slater, Conrad H. |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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