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We have developed a Superconducting Quantum Interference Device (SQUID) controller unit for Transition Edge Sensors (TES) readout, designed to be used in a space mission. The unit is made of 8 boards and each board can condition four SQUID array amplifiers. The board design is inspired by a similar one developed for ground based experiments, but specific changes have been made to adopt Components Off The Shelf (COTS) with space grade equivalents, to implement redundancy and cross-strapping capabilities. The design also includes the thermal path to lift the heat off the boards towards an in-house designed monolithic aluminum rack.

The discovery of a repeating Fast Radio Burst (FRB) source, FRB 121102, eliminated models involving cataclysmic events for this source. No other repeating FRB has yet been detected in spite of many recent FRB discoveries and follow-ups, suggesting repeaters may be rare in the FRB population. Here we report the detection of six repeat bursts from FRB 180814.J0422+73, one of the 13 FRBs detected by the Canadian Hydrogen Intensity Mapping Experiment (CHIME) FRB project during its pre-commissioning phase in July and August 2018. These repeat bursts are consistent with originating from a single position on the sky, with the same dispersion measure (DM), ~189 pc cm-3. This DM is approximately twice the expected Milky Way column density, and implies an upper limit on the source redshift of 0.1, at least a factor of ~2 closer than FRB 121102. In some of the repeat bursts, we observe sub-pulse frequency structure, drifting, and spectral variation reminiscent of that seen in FRB 121102, suggesting similar emission mechanisms and/or propagation effects. This second repeater, found among the first few CHIME/FRB discoveries, suggests that there exists -- and that CHIME/FRB and other wide-field, sensitive radio telescopes will find -- a substantial population of repeating FRBs., Comment: accepted by Nature

In this work, we have measured the properties of membrane-suspended bolometer thermal links and microstrip transmission lines in the transition-edge sensor arrays for the third-generation camera for South Pole Telescope (SPT-3G). A promising technique for controlling the end point of the release etch that defines the thermal link has been developed. We have also evaluated the microstrip loss in our detectors by measuring the optical efficiency of detectors with different lengths of microstrip line. The loss tangent is sufficiently low for the use in multi-chronic pixels for cosmic microwave background instruments like SPT-3G.

The third-generation upgrade to the receiver on the South Pole Telescope, SPT-3G, was installed at the South Pole during the 2016–2017 austral summer to measure the polarization of the cosmic microwave background. Increasing the number of detectors by a factor of 10 to ∼16,000 \ud ∼16,000\ud required the multiplexing factor to increase to 68 and the bandwidth of the frequency-division readout electronics to span 1.6–5.2 MHz. This increase necessitates low-thermal conductance, low-inductance cryogenic wiring. Our cold readout system consists of planar thin-film aluminum inductive–capacitive resonators, wired in series with the detectors, summed together, and connected to 4K SQUIDs by 10−μm \ud 10−μm\ud -thick niobium–titanium (NbTi) broadside-coupled striplines. Here, we present an overview of the cold readout electronics for SPT-3G, including assembly details and characterization of electrical and thermal properties of the system. We report, for the NbTi striplines, values of R≤10 −4 Ω \ud R≤10−4Ω\ud , L=21±1 nH \ud L=21±1 nH\ud , and C=1.47±.02 nF \ud C=1.47±.02 nF\ud . Additionally, the striplines’ thermal conductivity is described by kA=6.0±0.3 T 0.92±0.04 μW mm K −1 \ud kA=6.0±0.3 T0.92±0.04 μW mm K−1\ud . Finally, we provide projections for cross talk induced by parasitic impedances from the stripline and find that the median value of percentage cross talk from leakage current is 0.22 and 0.09% \ud 0.09%\ud from wiring impedance.

The South Pole Telescope third-generation (SPT-3G) receiver was installed during the austral summer of 2016–2017. It is designed to measure the cosmic microwave background across three frequency bands centered at 95, 150, and 220 GHz. The SPT-3G receiver has ten focal plane modules, each with 269 pixels. Each pixel features a broadband sinuous antenna coupled to a niobium microstrip transmission line. In-line filters define the desired band-passes before the signal is coupled to six bolometers with Ti/Au/Ti/Au transition edge sensors (three bands × \ud ×\ud two polarizations). In total, the SPT-3G receiver is composed of 16,000 detectors, which are read out using a 68× \ud ×\ud frequency-domain multiplexing scheme. In this paper, we present the process employed in fabricating the detector arrays.

We review the principle of operation and characteristics of all-fiber devices for dispersion compensation based on chirped distributed resonant coupling. These devices are the chirped Bragg grating, the chirped intermodal coupler, and the tapered two-dissimilar-core fiber. We discuss the use of a figure of merit to characterize equalizing filters. Based on a specific example, filter responses are computed and their performance is evaluated with a numerical simulation of an optical fiber link. Finally, design constraints are discussed. >