Testing and assembly of the detectors for the Millimeter Bolometer Array Camera on ACT

The Millimeter Bolometer Array Camera (MBAC) for the Atacama Cosmology Telescope consists of three Transition Edge Sensor (TES) arrays to make simultaneous observations of the Cosmic Microwave Background in three frequency bands. MBAC TESs are NASA Goddard Pop-Up Detectors (PUD) which are read-out by NIST time-domain multiplexers. MBAC is constructed by stacking 1 × 32 TES columns to form the 32 × 32 element arrays. The arrays are modular (connectorized) at the 1 × 32 column level such that array assembly is reversible and camera repair possible. Prior to assembly, each column is tested in a quick ( 2 h ) cycling 4He/3He adsorption refrigerator. Tests include measurements of TES current–voltage curves and TES complex impedance.