Ultasensitive TES detectors for FIR space astronomy.

We present results of the development of ultrasensitive transition edge superconducting (TES) detectors for the SAFARI far infrared (FIR) spectrometer, one of the instruments proposed for the Japanese-led SPICA telescope. Future FIR space missions require a combination of cooled optics and ultrasensitive detectors with noise equivalent power (NEP) levels on the order of 10
^-19
W/radic(Hz) or lower to be able to perform detailed spectroscopic surveys of the nearby and distant universe. We have developed TES detectors based on the mechanical suspension of an absorbing film connected to a TiAu bilayer thermometer on a thin SiN membrane. We describe the design of these detectors and measurements of their performance.