Isomer separation of Cu and Cu with a resonance ionization laser ion source

Radioactive copper isotopes were ionized with the resonance ionization laser ion source (RILIS) at the on-line isotope separator ISOLDE (CERN). Using the different hyperfine structure in the 3d10 4s 2 S1/2 – 3d10 4p 2 P01/2 transition the low- and high-spin isomers of 70 Cu were selectively enhanced by tuning the laser wavelength. The light was provided by a narrow-bandwidth dye laser pumped by copper vapor lasers (CVL) and frequency doubled in a BBO crystal. The ground state to isomeric state intensity ratio could be varied by a factor of 30, allowing to assign gamma transitions unambiguously to the decay of the individual isomers. It is shown that the method can also be used to determine magnetic moments. In a first experiment for the 1+ ground state of 70 Cu a magnetic moment of (+)1.8(3) μN and for the high-spin isomer of 70 Cu a magnetic moment of (±)1.2(3) μN could be deduced.