Dependence of metrologic characteristics of 57Co Moessbauer sources on surface activity

It is shown that the presence of a non-uniformity in 57Co radionuclide application to Moessbauer source surface leads to the fact that the shape of emission band, defined by a superposition of emission bands for different parts of the source is individual for each source. Therefore, a systematic error is introduced when processing GR-spectra. A necessity in changing the technology for producing such sources, in order to provide for applying 57Co nuclide with a non-uniformitz of no more than 10-15%, is shown. It is necessary to reduce the content of radioactive 56Co, 58Co, 60Co impurities in the sources, substituting 58Ni targets for targets of natural Ni. It is proposed to place Moessbauer sources into aluminium Joil capules to preserve the source tightness