Dr Alexander Chepurnov (Moscow State University)Dr Yury Suvorov (Ucla & INFN - LNGS)
Due to the large mass of the cryostats, containment tanks, passive shielding, and other mechanical parts of the modern low background detectors, requirements on their radiopurity are typically stringent. In this regard, the material radiopurity has to be less then 1 mBq/kg of U238 / Th232, which means that mass concentration should be < 0.1 ppb for U and < 0.25 ppb for Th. Traditionally, the field relies on specially selected low background stainless steel, electrochemical oxygen-free copper, or a combination of the two. But the most promising material in terms of physical and mechanical properties is titanium (or its alloys). Our analysis of various Ti samples together with external similar studies, show that the levels of contaminations of commercially available industrial titanium varies from 0.2 to 400 mBq/kg for U/Th. There fore, the only possible way to obtain the material with a low and controlled level of contamination is to develop (or improve the existing) the production technology and to build the dedicated manufactory line.
Dr Alexander Chepurnov (Moscow State University)
Dr Yury Suvorov (Ucla & INFN - LNGS)