Progress toward BLISS, the background-limited infrared-submillimeter spectrograph for SPICA

Abstract

We are developing the Background-Limited Infrared-Submillimeter Spectrograph (BLISS) for SPICA to provide a breakthrough capability for far-IR survey spectroscopy. The 3.2-meter, actively-cooled (T<6K) SPICA telescope allows mid-IR to submm observations which are limited only by the natural backgrounds, and BLISS is designed to operate near this fundamental limit. BLISS-SPICA provide a line sensitivity of 10 −20 W m −2 , thereby enabling spectroscopy of dust-obscured galaxies at all epochs back to the first billion years after the Big Bang (redshift 6), and study of all stages of planet formation in circumstellar disks.BLISS covers the 35-430 micron waveband at moderate resolving power (300<R<700) in six grating spectrometer bands, each coupling at least two 2 sky positions simultaneously. The instrument is cooled with an on-board refrigerator to 50 mK for optimal sensitivity. The detector package in the goal implementation is 4200 silicon-nitride micro-mesh leg-isolated bolometers with superconducting transition-edge-sensed (TES) thermistors, read out with a cryogenic time-domain multiplexer. The instrument is designed to fit within the stringent SPICA resource allocations for mass and heat lift, and to mitigate the impact of cosmic rays. We report on this design and our progress in prototyping and validating the BLISS spectrometers and prototype cooler. A companion paper in Conference 8452 (A. Beyer et al.) discusses in greater detail the progress in the BLISS TES bolometer development.

Transition Edge Sensors and Kinetic Inductance Detectors in Astronomical Instruments

“…The TES bolometers designed for the SAFARI instrument on the SPICA satellite have saturation powers of a few femtoWatts and phonon NEPs on the order of 10 W Hz 19 - (Roelfsema et al 2012). Achieving these sensitivities requires very good control of stray light and this has recently been demonstrated by groups at JPL and SRON (Bradford et al 2012;Suzuki et al 2016). In particular, the measurements at SRON showed that detectors with resistive absorbers had excess noise above the phonon noise limit in a first test while those without the absorbers reached the phonon noise.…”