The beta decay of ${\mathrm{F}}^{20}$ has been investigated with a magnetic lens spectrometer. The decay proceeds mainly to the first excited state of ${\mathrm{Ne}}^{20}$ by a beta ray of maximum energy 5.419±0.013 Mev, followed by a gamma ray of energy 1.627±0.005 Mev. The excited state transition, with comparative half-life $ft=9.73\mathrm{}\times {10}^4$ seconds, has the allowed shape down to 1 Mev.

A magnetically compensated stilbene scintillation counter has been employed to show that the counts beyond the end point of the intense beta component are due predominantly to scattered electrons and room background. The direct transition to the ground state of ${\mathrm{Ne}}^{20}$ ($Q=7.047\mathrm{}\pm 0.014$ Mev) is estimated to have a relative intensity of less than ∼3.2×${10}^{-4\mathrm{}}$ of the excited state transition, corresponding to a comparative half-life $\mathrm{ft}\gtrsim {10}^9$ seconds.

• Received 1 February 1954

DOI:https://doi.org/10.1103/PhysRev.95.761