Readout of two-kilopixel transition-edge sensor arrays for Advanced ACTPol

• Published in: arXiv.org
• Main Authors: Henderson, Shawn W, Stevens, Jason R, Amiri, Mandana, Austermann, Jason, Beall, James A, Chaudhuri, Saptarshi, Hsiao-Mei, Cho, Choi, Steve K, Cothard, Nicholas F, Crowley, Kevin T, Duff, Shannon M, Fitzgerald, Colin P, Gallardo, Patricio A, Halpern, Mark, Hasselfield, Matthew, Hilton, Gene, Shuay-Pwu Patty Ho, Hubmayr, Johannes, Irwin, Kent D, Koopman, Brian J, Li, Dale, Li, Yaqiong, McMahon, Jeff, Nati, Federico, Niemack, Michael D, Reintsema, Carl D, Salatino, Maria, Schillaci, Alessandro, Schmitt, Benjamin L, Simon, Sara M, Staggs, Suzanne T, Vavagiakis, Eve M, Ward, Jonathan T
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 20.07.2016
• Subjects: Aliasing; Angular resolution; Big Bang theory; Bolometers; Cosmic microwave background; Cosmology; Division; Inductance; Multiplexing; Optimization; Physics - Cosmology and Nongalactic Astrophysics; Physics - Instrumentation and Methods for Astrophysics; Pixels; Polarization; Sensor arrays; Sensors; Superconducting quantum interference devices
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1607.06064

Advanced ACTPol is an instrument upgrade for the six-meter Atacama Cosmology Telescope (ACT) designed to measure the cosmic microwave background (CMB) temperature and polarization with arcminute-scale angular resolution. To achieve its science goals, Advanced ACTPol utilizes a larger readout multiplexing factor than any previous CMB experiment to measure detector arrays with approximately two thousand transition-edge sensor (TES) bolometers in each 150 mm detector wafer. We present the implementation and testing of the Advanced ACTPol time-division multiplexing readout architecture with a 64-row multiplexing factor. This includes testing of individual multichroic detector pixels and superconducting quantum interference device (SQUID) multiplexing chips as well as testing and optimizing of the integrated readout electronics. In particular, we describe the new automated multiplexing SQUID tuning procedure developed to select and optimize the thousands of SQUID parameters required to readout each Advanced ACTPol array. The multichroic detector pixels in each array use separate channels for each polarization and each of the two frequencies, such that four TESes must be read out per pixel. Challenges addressed include doubling the number of detectors per multiplexed readout channel compared to ACTPol and optimizing the Nyquist inductance to minimize detector and SQUID noise aliasing.