SPICA Far-IR Spectrometer: SAFARI
With as a prime driver the galaxy evolution science, the SAFARI spectrometer is primarily optimised to achieve the ultimate sensitivity, within the bounds of the available resources (thermal, number of detectors, power, mass), at a moderate resolution of R~300 instantaneously over the full 34 to 230 µm domain. A secondary driver is the requirement to also study at higher wavelength resolution the more detailed properties of line profiles, e.g. for the in-fall and outflow of matter from active galactic nuclei, this leads to the implementation of an additional high resolution mode utilising a Martin-Puplett interferometer for pre-dispersion of the signal. With the grating-based design, the SAFARI/SPEC sensitivity of the R~300 mode will be about 5 x 10-20 W/m2 (5σ, 1hr) for a Transition Edge Sensor (TES) NEP of 2×10-19 W/√Hz, compatible with the sensitivity requirement as dictated by the SPICA science drivers. The design allows for further improvements in TES performance, these will directly lead to better overall instrument sensitivity. The SAFARI fact sheet shows the full specifications for the baseline SAFARI instrument. An explanatory note is also provided.