Temperature Dependence of the UCN Loss Rate
  We report about the first results obtained with our Ultra High Vacuum cryostat recently commissioned at HMI to study Ultra Cold Neutrons(UCN) loss rate under low temperatures(down to 4K) and well controlled sample environment. Our analysis of the temperature dependence of UCN loss rate on Cu surface allowed us to rule out the subbarier model in support of the 1/v model and propose a reasonable explanation of the low temperature upscattering. 
S. Arzumanov, J. Butterworth, R. Golub, P. Geltenbort, E. Korobkina