BARS-3M - portable difractionless XRF analyzer for investigation of art works materials in-situ

The spatial museum BARS-3M analyzer (USSR priority, patents No 8599891, No 1111080, No 3769002) is suitable for qualitative and semi-quantitative determination of chemical composition of inorganic pigments used in the field of geology. It consists of two units: a replaceable spectrometric head (SH) with X-ray source and a control unit. Range of analyzed elements - from Ca to U, threshold sensitivity - up to 0.05%; the main instrument error - 0.8%, mass - 15 kg. Due to the new spectrometric channels (SC), BARS-3M allows to increase the number of elements that can be determined. In addition to SC for 14 elements (Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Pb/As, Sr/U) new SC for Ba, Au, Hg, Se/Pb based on differential detector circuit (DDC) and SC for Ag, Cd, Sb, Sn, Ca based on differential filter circuit (DFC) are used. This makes it possible not to increase X-ray tube high voltage. Three replaceable SH on DDC are tuned to definite groups of pigments (white, blue-green, yellow-brown). SC on DFC are assembled together to form a separate SH. X-ray collimator can define 15-0.3 cm2 surface area. BARS-3M has been tested in analyzing surface layers of colour glasses, porcelains, paintings and frescos. It allows to identify and classify inorganic pigments, to define the area of conservation, etc. (author)