Shacklett, Robert Lee (1956) A precision measurement of the LII-LIII x-ray energy level difference in some heavy elements and a comparison with the predictions of the Schawlow-Townes theory of the nuclear size effect. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-06252004-140127
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The recent experimental determinations of the radius of the nuclear charge distribution all tend to give an approximate value of [...] with [...]. However, the theoretical work of Schawlow and Townes on the effect of the finite nuclear size on the [...] X-ray level splitting, through a comparison with already existing X-ray data, yielded a value of [...]. This thesis describes an experimental determination of the [...] splitting for six of the heavy elements based on two-crystal spectrometer measurements of the Bragg angles of the [...] and [...] X-ray lines of W, Pt, Bi, Th, U, and Pu. The Bragg angles of these lines, corrected for vertical divergence, temperature, and crystal diffraction pattern asymmetry, are reported with a mean standard deviation of about 0.2 second of arc. The values of the [...] splitting calculated from the wavelengths of the lines have a relative accuracy of about 50 parts per million. When the experimental splittings are compared to the theoretical values which include the nuclear size effect, a value of [...] is obtained. The suggestion is made that inaccuracies in the previous measurements of the [...] wavelengths for several high Z elements might have contributed to the large value of [...] obtained by Schawlow and Townes. When the theoretical splitting is calculated with corrections for vacuum polarization and a nuclear radius constant of [...], a comparison with experiment shows that a discrepancy remains which is then used to evaluate an empirical correction term. The sign, magnitude, and Z-dependence of this term suggest that the remaining discrepancy might arise from the Lamb shift effect.
|Item Type:||Thesis (Dissertation (Ph.D.))|
|Degree Grantor:||California Institute of Technology|
|Division:||Physics, Mathematics and Astronomy|
|Thesis Availability:||Public (worldwide access)|
|Defense Date:||1 January 1956|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Imported from ETD-db|
|Deposited On:||28 Jun 2004|
|Last Modified:||26 Dec 2012 02:53|
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