INVESTIGATIONS OF A RF STORED CA(-D FORBIDDEN TRANSITIONS() ION CLOUDAND OBSERVATION OF THE S)

In order to exploit the capability of a high-Q transition for a freque ncy standard in the optical domain (729 nm), a stored Ca+ ion cloud in a medium-size ion trap is investigated. Long confinement times are ob tained in the presence of helium as a buffer gas in the range 10(-6)-1 0(-8) mbar and at a pseudopotential well depth of 62 eV. First observa tions of the electric quadrupole line were achieved by direct excitati on of one of the first metastable doublet levels (tau almost-equal-to 1 s). Utilisation of a grating-stabilised diode laser in order to prob e both levels when only one level is initially populated allows us to observe almost equal fluorescence intensities of both forbidden lines that show the presence of a strong fine structure mixing which exists in addition to quenching.