Beta spectrum of F20

The shape of the β-ray spectrum of F20 has been investigated as a test of the weak magnetism prediction of the conserved vector current theory. Using the radiative width of the analog M1 decay in Ne20 to determine the magnetic form factor we calculate, from conserved vector current theory, a deviation of the β spectrum from the allowed shape of +1.23±0.03% MeV-1. Higher order terms reduce the slope to 0.94% MeV-1. The spectrum was measured with an iron-free intermediate-image magnetic spectrometer and the deviation was found to +0.4±0.5% MeV-1 or somewhat smaller than the conserved vector current prediction. [RADIOACTIVITY F20: measured β-spectrum shape; compared with CVC prediction.]