Abstract
FURTHER experiments on the reflection of hydrogen positive rays from crystals, similar to those described in NATURE for Jan. 11, have shown that the phenomenon is more complex than might have been expected. More than a hundred photographs showing reflected rays have been obtained under various conditions, and they show several features of interest. Great differences have been found in the reflecting powers of different samples of calcite. Two were found that gave strong reflected rays when the glancing angle was less than two degrees. The images obtained on Schumann plates placed at right angles to the beam may be properly termed reflection patterns, as they show considerable complexity, vary in a regular manner with the angle of incidence, and can be reproduced at will with the same setting of the crystal and speed of the rays. Six other calcite crystals gave reflection patterns containing fewer lines or lines on a fogged background. Reflected rays were also observed with a diamond which was kindly loaned by Dr. D. Cooksey. A natural cleavage face of this diamond had been used in experiments on the reflection of gamma rays. A highly polished face gave indistinct patterns on a fogged background. Clear lines were obtained from two other faces, one of which was the natural cleavage face, and the other a face that had been cut and appeared rough, due to saw marks. No reflected rays were found in a few trials with rock salt, galena, and magnetite.
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DEMPSTER, A. Reflection of Positive Ions by Crystals. Nature 125, 741 (1930). https://doi.org/10.1038/125741a0
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DOI: https://doi.org/10.1038/125741a0
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