Chronology of Milestone Events in Particle Physics - ROBSON 1950
Chronology of Milestone Events in Particle Physics


Robson, J.M.;
Radioactive Decay of the Neutron
Phys. Rev. 77 (1950) 747(A);

Full Text
The positive particle from the radioactive decay of the neutron has been identified as a proton from a measurement of charge to mass. A collimated beam of neutrons emerging from the Chalk River pile passes between two electrodes in an evacuated tank. One electrode is held at a positive potential, up to 20 KeV, while the other electrode is grounded and forms the entrance aperture to a thin lens magnetic spectrometer, the axis of which is perpendicular to the beam of neutrons. The positive decay particles can be focused on the first electrode of an electron multiplier. The background counting rate is 60 c.p.m. A peak of 80 c.p.m. is observed above background when the magnetic field is adjusted for protons of energy expected from the electrostatic field. When a thin boron shutter is placed in the neutron beam, the proton peak disappears. Preliminary estimates of the collecting and focusing efficiency and the neutron flux indicate a minimum half-life of 9 minutes and a maximum of 18 minutes for the neutron.

Accelerator REACTOR Detectors SPEC

  n p X

Particles studied
  n w

Record comments
First observation of neutron beta decay.
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