The spin sequence of the first and second excited levels of Ne19

A magnetic-lens type beta-ray spectrometer has been used to measure the relative intensities of internal conversion electrons and also of photoelectrically converted gamma-rays for ground state transitions of the first- and second-excited levels of Ne19. These levels of Ne19 were excited by the reaction F19(p, n)Ne19∗. The relative intensities of the internal conversion electrons and the photoelectrons show that the internal conversion coefficient for the first-excited to ground state transition is about an order of magnitude larger than the internal conversion coefficient for the second-excited to ground state transition. Therefore, the first-excited level of Ne19 must have a larger total angular momentum than the second-excited level. This result confirms the interpretation given to the mean life measurements of these transitions; consequently, the reversed spin sequence of the first- and second-excited levels in the mirror nuclei Ne19 and F19 appears now to be well established. The level energies inferred from the photoelectron and internal conversion electron spectra are 241±4 and 271±4 keV for the first- and second-excited levels of Ne19.