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We study x-ray absorption spectra below the O 1s threshold in Sc-doped stoichiometric strontium titanate (SrTiO₃). We find hole states at the top of the valence band and acceptor-induced levels just above the Fermi level. The x-ray absorption spectra features and their temperature dependence are in good agreement with electrical-conductivity studies on the same samples. It is concluded that Sc-doped SrTiO₃ is a p-type semiconductor with deep acceptor levels lying in the middle of the band gap.

A compact proton synchrotron using combined function magnets is proposed to help realize the wider availability of charged particle cancer therapy facilities. This combined function magnet was designed with the help of three-dimensional magnetic field calculations to take account of a realistic fringe and the interference among the magnetic poles. An evaluation scheme for tune values based on particle tracking was developed to improve the magnet design. To verify the magnet design, a model magnet was fabricated and measured. In order to achieve a tune value evaluation from the measured magnetic field, schemes for accurate field mapping and field interpolation were developed. From the tune value evaluation of the measured magnetic field, it was thought that the performance of the model magnet was good enough to construct a synchrotron. In this paper, we report details of the design and the evaluation scheme for the combined function magnet and the results of the field measurements of the model magnet.

It is found that the proton is strongly absorbed in heavily Sc-doped SrTiO₃. Neutron-diffraction measurements were performed using single crystals. The O-H distance is found to be about 1.2 Å and the proton concentration is estimated to be about 2 mol % for SrTi_0.98Sc_0.02O₃. Protonic conduction was observed in Sc-doped SrTiO₃ by ac-conductivity measurements in wet air, while the hole conductivity was observed in dry air. The proton is bound by the oxygen ion as if the proton makes the hydrogen bond between two oxygen ions, which might be responsible for the high protonic conductivity in this material. © 1996 The American Physical Society.