Measurement of the Shape Factor for the Beta Decay of $^{14}$O

Understand

We report results from an experiment designed to test the conserved vector current (CVC) hypothesis by measuring the shape of the $\beta$-decay spectrum for the allowed $0^+\rightarrow 1^+$ ground state decay of $^{14}$O.

• Measurements of the spectrum intensity were obtained with a superconducting beta spectrometer and will be reported for positron kinetic energies ranging from 1.9 to 4.0 MeV.
• After dividing out phase space, Coulomb, and other correction factors, the resulting shape function has a negative slope of several per cent per MeV.
• We define a parameter $a'$, which is essentially a measure of the average slope of the shape function over the energy range of the measurements, and determine its value to be $a' = -0.0290 \pm 0.0008$ (stat.) $\pm 0.0006$ (syst.).