Transmutations of Sodium by Deutons

Phys. Rev. 47, 17 – Published 1 January 1935
Ernest O. Lawrence


Under deuton bombardment sodium emits protons. neutrons and alpha-particles, and becomes radioactive, The radioactive substance, which was shown by chemical tests to be radio-sodium, decays with a half-life of 15.5 hours, emitting electrons with energies up to 1.2 mv, and 5.5±0.5 mv gamma-rays. One microampere of 1.7 mv deutons bombarding a target of NaCl produces about 4×106 radio-sodium atoms per second. The rapid increase in yield with voltage predicted by the Gamow formula has been found, and with the higher current and voltage that soon will be available, the already large yield of radio-sodium just stated should be increased more than 100-fold. Doubtless radio-sodium will find many uses in the physical and biological sciences. The number of emitted protons equals, within experimental uncertainty, the number of radio-sodium atoms created; this supports the view that Na24 is the radioactive isotope formed. The protons are distributed in ranges up to 49±2 cm (air at 20°C, 760 mm) with a rather pronounced group in the neighborhood of 17 cm. The number of neutrons, emitted presumably in a reaction in which Mg24 is formed, is of the same order of magnitude as the number of protons. The alpha-particles have a range of 6.5±0.3 cm and are emitted in a less frequent reaction in which presumably Ne21 is formed. Balance of energy in the reactions leads to the following atomic masses: Na23,22.992±0.001;  Na24,24.000±0.003;  Mg24,23.993±0.003.


  • Received 27 October 1934
  • Published in the issue dated January 1935

© 1935 The American Physical Society

Authors & Affiliations

Ernest O. Lawrence

  • Radiation Laboratory, Department of Physics, University of California

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