High mechanical Q-factor measurements on calcium fluoride at cryogenic temperatures R. Nawrodt, A. Zimmer, T. Koettig, S. Nietzsche, M. Thürk, W. Vodel and P. Seidel Eur. Phys. J. Appl. Phys., 38 1 (2007) 53-59 Published online: 22 February 2007 DOI: 10.1051/epjap:2007040