Abstract
LONDON Royal Society, March 7. C. T. R. WILSON and J. G. WILSON: On the falling cloud-chamber and on a radial-expansion chamber. The advantages of removing a cloud -chamber from a confined space such as that between the poles of a magnet by letting it fall, and photographing the tracks while the chamber is falling freely, are pointed out. A new type of cloud-chamber, which has the form of a shallow cylinder with plane glass ends and in which the motion of the air during expansion is radial, gives good results. It is found, as anticipated, that dropping the cloud-chamber and photographing while it is falling freely enables undistorted track pictures to be obtained (by eliminating gravity) when the interval between expansion and illumination is prolonged to such an extent, that with the cloud -chamber stationary, distortion by convection currents has become serious. P. I. DEE and C. W. GILBERT: The transmutation of heavy hydrogen investigated by the cloud track method. The 2He3 nuclei produced in the reaction have been detected in the expansion chamber by passing a beam of artificially accelerated 1H.2 ions into a gas mixture containing heavy hydrogen. The range of this group of particles has been measured and. is 4·3±0·2 mm. for zero bombarding energy. The neutrons produced in the same bombardment have an energy of 1·8 ±0·2×06 electron volts. These results are in agreement with the application of the conservation of momentum to the process assumed. A value of 1-0080±0-004 is thereby deduced for the mass of the neutron.
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Societies and Academies. Nature 135, 446–448 (1935). https://doi.org/10.1038/135446a0
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DOI: https://doi.org/10.1038/135446a0