Nuclear Polarization by Means of Laser Optical Pumping and its Application to the Research for Nuclear Structure.

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Just after the laser system has been installed, the isotope shift of erbium I was investigated. The transition of 582.7 nm for the natural Er I was used for the measurement of the isotope shift and thus of the change of the mean-square nuclear charge-radii. Also the hyperfine structure of <^(197)Er> was investigated. Even-odd staggering in the mean square nuclear charge radii was also observed in the Er, similar to the neighboring isotopes.Production rate of the <^(211m)Po> isomer was measured with the ( <alpha> ,n) reaction. The transition strength for the 16831 <cm^(-1)> level in the Po was also investigated for the use in laser optical pumping. Feasibility study for the possible application of spin-exchange reaction to the achievement of nuclear polarization of Po is now in progress.Nuclear polarization of <^(170)Tm> (unstable) in <SrF_2> crystal was produced with the laser optical pumping via the excitation of broad absorption band in divalent Tm atom. Nuclear alignment and polarization were measured with the detection of beta and gamma rays emitted in the decay of unstable Tm isotope. Obtained nuclear polarization was about 8 <+!-> 4 %, indicating potential applicability of this method for the study of the nuclear structure.