First observation of a resonance ionization signal on242mAm fission isomers

The feasibility of a hyperfine spectroscopy on^242mAm fission isomers has been demonstrated at the low target production rate of 10/s. The experimental method employed is based on resonance ionization spectroscopy in a buffer gas cell with detection of the ionization process by means of the fission decay of the isomers. The resonance ionization has been performed in two steps, utilizing an excimer dye laser combination with a repetition rate of 300 Hz. The first resonant step proceeds through theJ=7/2 term at 21440.35 cm⁻¹, which has been excited with the tuncable dye laser beam of a wavelength of 466.28 nm, the second non-resonant step is achieved with the 351 nm radiation of the excimer laser itself, running with XeF. The frequency scan of the tuneable dye laser exhibits a broad resonance ionization signal, the width of which is most likely explained by the magnetic hyperfine interaction.