Measurement of the quality factor of a new low-frequency differential accelerometer for testing the equivalence principle.

A cryogenic differential accelerometer has been developed to test the weak equivalence principle to a few parts in 10(15) within the framework of the general relativity accuracy test in an Einstein elevator experiment. The prototype sensor was designed to identify, address, and solve the major issues associated with various aspects of the experiment. This paper illustrates the measurements conducted on this prototype sensor to attain a high quality factor (Q ∼ 10(5)) at low frequencies (<20 Hz). Such a value is necessary for reducing the Brownian noise to match the target acceleration noise of 10(-14) g/√Hz, hence providing the desired experimental accuracy.

Voltage breakdown follower avoids hard thermal constraints in a Geiger mode avalanche photodiode.

A novel approach to single-photon detection by means of an avalanche photodiode is described and preliminary results obtained by implementation of a prototype are reported. The electronic circuit (breakdown voltage follower) avoids the use of complex temperature controls typically used with these devices, thus reducing system complexity and cost. Data obtained without any thermoregulation show the same behavior with respect to systems thermoregulated to within a few hundredths of a degree celsius.