Low-noise voltage-sensitive preamplifier operated in the Kelvin range for cryogenic detectors

Low-l/f-noise GaAs MESFETs (metal-semiconductor field-effect transistors) were used to develop a preamplifier for cryogenic detectors. It operates at 1 K, has a voltage gain of 50, a bandwidth of 8 MHz and a noise level of 1.3 nV/ square root Hz at 100 kHz. It is used to amplify the signal of bolometric detectors, avoiding microphonics and RFI (radio-frequency interference) energy pick-up which heats the detector. It can also be used for risetime studies on fast detectors.>