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The Terahertz Intensity Mapper (TIM) is a NASA far-infrared balloon mission designed to perform [CII] intensity mapping of the peak of cosmic star formation. To achieve this goal, TIM will fly two grating spectrometers that together cover the 240–420 μ m wavelength range at a spectral resolution, R ∼ 250 . Each spectrometer will require a large format ( ∼ 3600 detectors) array of dual-polarization sensitive detectors, which are photon noise limited at the 100 fW of loading expected during operation. We present the design of a fully-aluminum low-volume lumped-element kinetic inductance detector that incorporates a novel "chain-link" absorber design. Operating at 215 mK, we demonstrate this detector achieves a photon noise limited performance at 100 fW of optical loading with a white noise spectrum down to 1 Hz. Based upon noise measurements of a dark detector, which shows a quasi-particle lifetime of 300 μ s , these KIDs are expected to achieve a detector-limited noise equivalent power of ∼ 1.3 × 10 - 18 W / Hz . [ABSTRACT FROM AUTHOR]

We report on the kinetic inductance detector (KID) array focal plane assembly design for the Terahertz Intensity Mapper (TIM). Each of the 2 arrays consists of 4 wafer-sized dies (quadrants), and the overall assembly must satisfy thermal and mechanical requirements, while maintaining high optical efficiency and a suitable electromagnetic environment for the KIDs. In particular, our design manages to strictly maintain a 50 μ m air gap between the array and the horn block. We have prototyped and are now testing a sub-scale assembly which houses a single quadrant for characterization before integration into the full array. The initial test result shows a >95% yield, indicating a good performance of our TIM detector packaging design. [ABSTRACT FROM AUTHOR]

We discuss the design and optimization of the absorber for Terahertz Intensity Mapper, a balloon-borne kinetic inductance detector spectrometer. The novel "chain-link" absorber design offers excellent performance, independent optimization for both polarizations, and robust fabrication. Electromagnetic simulations indicate in-band absorption efficiency over ∼ 90 % in both linear polarization modes. DC measurements on different film thicknesses indicate the desired sheet resistance. [ABSTRACT FROM AUTHOR]