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The beta-ray spectra of radioactive manganese, arsenic and indium was obtained by measuring tracks produced in a cloud chamber situated in a magnetic field. Manganese and arsenic give spectra which can be resolved into two components. The end points of the two components are: for Mn, 1.2 and 2.9 MEV; for As, 1.09 and 3.4 MEV. The endpoint for In is 1.45 MEV.
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Brown et al. (1936) studied this question.
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