Characteristics of the diamond detector for use in the radiation therapy for the relative dosimetry of photon, electron, proton beams are given in the paper. The advantages of the detector as compared with ionising chambers and Si-diodes are presented.

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The centrifugation method has advantages in producing silicon isotopes. The selection of appropriate working gas, development of gas centrifuges, their arrangement for effective separation of the isotopes and optimization of the production process are considered. The resulting mole fraction of 28Si is better than 0,999 9. The requirements for the production processes in growing single crystals and the related problems are analysed in detail and estimates of the uncertainties associated with the necessary tests are given.

A new way to realize the ampere by the method of superconducting mass levitation is proposed. The approach promises to simplify the measurement procedure because it substitutes the "mechanical" joule realization by measurements in the levitation mode of the periods of small vertical oscillations of the mass. One has to measure the period value, with constant current flowing in the levitating coil, and again with the mass in the same position but with the coil short-circuited to maintain the magnetic flux constant.

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