High mechanical Q-factor measurements on calcium fluoride at cryogenic temperatures

Mechanical Q-factor measurements of single crystalline calcium fluoride CaF2 bulk material are presented. Resonant modes between 27 and 100 kHz were investigated on a cylindrical test sample (0 75 mm x 75 mm). For selected modes low temperature measurements of the mechanical Q-factor were done within a temperature range from 5 to 300 K. For the Q-measurements a ring-down technique was used. The substrate was suspended as a pendulum by means of a tungsten wire loop. The highest Q-factor has been achieved around 60 K with 3 x 10(8) which is the highest Q-factor reported on CaF2 up to now.