Development of Polarized Internal Target

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At the first stage of development of a polarized target, we polarized a vapored alkaline-metal with a circularly polarized laser beam. A spin-exchange cell of Pyrex glass was coated with a drifilm from dichloro-dimethyl-silane plus water to avoid depolarization. Rubidium atoms were optically-pumped in a magnetic field of 3,000 gauss in a solenoid coil to reduce the radiation trapping effect.Polarizations of rubidium atoms, deuterium atoms and deuterons are needed to be measured for assessment of the performance. We constructed a system to measure the polarization and gas-thickness using Faraday rotation and evaluated them under various conditions. The system can decide the rotation angle within an error of 0.01ﾟ. A rotation angle of 0.56 degrees was observed for vacant threefold cells of total 1.4 cm thickness in 2 k gauss at the wavelengthy of 780.8nm. The Verdet constant of Pyrex glass was obtained to be 2*10^<-4> degrees/gauss・cm from the result. For the rubidium atoms, our preliminary result showed a polarization of 0.4 at a gass thickness of 4*10^<13> atoms/cm^2.Deuterium molecules are dissociated into atoms at the first stage. An rf dissociation system was constructed for its sake. In a mass spectrum measured by a quadrupole mass spectrometer, a peak of a mass number of 2 was observed. It showed that the molecules were dissociated into atoms in the system. However the peak disappeared after a short time, because the coating was destroyed by rf or activated deuterium atoms. It is one of probelms to be solved for the development of the polarized target how the coating is protected from such a destruction.We are also developing a Lamb-shift polarimeter to measure the polarization of the deuterium nucleus (deuteron).