1. S.R. Bandleret al. Low Temperature Detectors for Neutrinos and Dark Matter, editors N.E. Booth and G.L. Salmon (Editions Frontieres, Gir-sur-Yvette, 1991), p.421.
2. R. Torii,et al., Rev. Sci. Instrum.63, 230 (1992).
3. The figure of 100 K is an average value provided to us by M.J. Cardillo (ATT-Bell Labs.) based on a variety of experimental data, and depends on the crystalographic orientation of the surface. See also R. Luchese and J. Tully, Surf. Sci.137, 570 (1984).
4. A.L. Fetter,Physics of Liquid and Solid Helium, edited by K.M. Benneman and J.B. Ketterson (John Wiley, New York, 1976).
5. J.B. Birks,The Theory and Practice of Scintillation Counting, (MacMillan, New York, 1964). M. Stocktonet al., Phys. Rev. Lett.24, 654 (1970). C.M. Surkoet al., Phys. Rev. Lett.24, 657 (1970).