Long Range -Particles

• DOI: 10.1038/112938b0
• Publication Date: 2008-01-02T22:21:53Z
• Authors: L. F. BATES; J. STANLEY ROGERS
• Keywords: Radium; α particles; Isotopes of thorium

IN a letter to NATURE of September 22, p. 435, we stated that, in addition to the -rays of range 6.97 cm., radium active deposit emits particles of ranges 9.3, 11.2, and 13.3 cm. respectively. It has since been found that, in addition to the -rays of ranges 4.8 and 8.6 cm., thorium active deposit emits particles of ranges 11.5 (previously recorded by Rutherford), 15.0 and 18.4 cm. respectively, and that the emission of every 106 -rays of range 8.6 cm. is accompanied by the emission of 220, 47, and 55 particles of the above ranges. In the case of actinium active deposit evidence of particles of range greater than 6.5 cm. was found, but the sources available were not sufficiently intense to allow their range to be determined with accuracy.