Abstract
DR. A. NODON has carried out a series of experiments, which he interprets as showing the existence of solar radiations of shorter wave-length than the X- and Y-rays, and regards as the cause of radioactive disintegration. He has sent us papers on this work, one of which was presented to the Paris Academy of Sciences on June n, 1923. A radiographic plate, protected by a lead screen with a small central hole, was enclosed in a black cardboard case, on the outer surface of which a small quantity of radium salt was fixed by an adhesive. The effect produced on the sensitive plate was found to be variable, depending on the electromagnetic activity of the sun; in some cases direct exposure to the sun's rays produced strong impressions on the plate in a few minutes, while in others the impressions were weak after several hours' exposure, and this did not depend on differences in the heating effect of the sun's rays. During periods of solar activity the difference in the impressions produced in direct sunlight and inside a room or in a cellar was found to be very great, being much smaller indoors. The solar radiations do not affect the plate if no radium or other radioactive substance is present. The variations of the horizontal component of the earth's magnetic field were measured by means of a magnetograph, and it was assumed that these variations are closely related to the solar activity.
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The Radioactivity of Radium in Relation to Solar Radiation. Nature 113, 443 (1924). https://doi.org/10.1038/113443a0
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DOI: https://doi.org/10.1038/113443a0