Invited Article: Millimeter-wave bolometer array receiver for the Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument

Abstract

The Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument is a millimeter-wave cryogenic receiver designed to observe galaxy clusters via the Sunyaev-Zel'dovich effect from the 12 m APEX telescope on the Atacama plateau in Chile. The receiver contains a focal plane of 280 superconducting transition-edge sensor (TES) bolometers instrumented with a frequency-domain multiplexed readout system. The bolometers are cooled to 280 mK via a three-stage helium sorption refrigerator and a mechanical pulse-tube cooler. Three warm mirrors, two 4 K lenses, and a horn array couple the TES bolometers to the telescope. APEX-SZ observes in a single frequency band at 150 GHz with 1' angular resolution and a 22' field-of-view, all well suited for cluster mapping. The APEX-SZ receiver has played a key role in the introduction of several new technologies including TES bolometers, the frequency-domain multiplexed readout, and the use of a pulse-tube cooler with bolometers. As a result of these new technologies, the instrument has a higher instantaneous sensitivity and covers a larger field-of-view than earlier generations of Sunyaev-Zel'dovich instruments. The TES bolometers have a median sensitivity of 890 μK(CMB)√s (NEy of 3.5 × 10(-4) √s). We have also demonstrated upgraded detectors with improved sensitivity of 530 μK(CMB)√s (NEy of 2.2 × 10(-4) √s). Since its commissioning in April 2007, APEX-SZ has been used to map 48 clusters. We describe the design of the receiver and its performance when installed on the APEX telescope.

Weak-lensing mass calibration of the Sunyaev–Zel’dovich effect using APEX-SZ galaxy clusters

“…The APEX-SZ (Dobbs et al 2006;Schwan et al 2011;Dobbs et al 2012) instrument was a bolometer array which operated from 2005 to 2010 on the 12-meter Atacama Pathfinder Experiment (APEX) telescope (Güsten et al 2006). It consisted of 280 transition-edge-sensor (TES) bolometers spread over an instantaneous 23 arcminute field-of-view (FoV).…”

“…In this work, we employ a sample of 39 galaxy clusters observed with the SZ effect using the APEX telescope (Schwan et al 2011). To provide an accurate mass calibration of the integrated Comptonization, we measure the scaling relation of the Comptonization with weak-lensing de-rived masses of an X-ray selected sample with a well-defined selection function.…”

Standoff passive video imaging at 350 GHz with 251 superconducting detectors

“…To solve this problem our system uses an approach followed by other systems. 15 The Si detector wafers are first glued to another Si wafer. Then the wafer stack is attached to a 3.175 mm thick Invar plate using low-temperature thermal grease.…”

Front Matter: Volume 8444

“…[130][131][132][133][134][135][136][137] ). In parallel to the development of the TES bolometers, a large effort has been spent in the development of the readout electronics, which uses SQUIDs to read and multiplex a large number of detectors with a limited number of wires, thus maintaining the heat load on the cryostat at manageable levels.…”

“…[159][160][161] ). Large mm-wave telescopes ( 109,110,136 ), coupled to imaging multi-band arrays of bolometers, are now operating in excellent sites and produce a number of detections and maps of the SZ effect in selected sky areas, discovering new clusters, and establishing cluster and cosmological parameters.…”