Characterization of Transition Edge Sensors for the Millimeter Bolometer Array Camera on the Atacama Cosmology Telescope

The Atacama Cosmology Telescope (ACT) aims to measure the Cosmic Microwave Background (CMB) temperature anisotropies on arcminute scales. The ACT project is producing high-resolution millimeter-wave maps of the sky, which can be analyzed to provide measurements of the CMB angular power spectrum at large multipoles to augment the extant data to improve estimation of such cosmological parameters as the scalar spectral index and its running, the density of baryons, and the scalar-to-tensor ratio. When combined with X-ray and optical observations, the millimeter-wave maps will help to determine the equation of state of dark energy, probe the neutrino masses, constrain the time of the formation of the first stars, and reveal details of the growth of gravitationally bound structures in the universe. This thesis discusses the characterization of the detectors in the primary receiver for ACT, the Millimeter Bolometer Array Camera (MBAC). The MBAC is comprised of three 32 by 32 transition edge sensor (TES) bolometer arrays, each observing the sky with an independent set of band-defining filters. The MBAC arrays are the largest pop-up detector arrays fielded, and among the largest TES arrays built. Prior to its assembly into an array and installation into the MBAC, a column of 32 bolometers is tested at approximately 0.4 K in a cryostat called the Super Rapid Dip Probe (SRDP). The purpose of this paper is twofold. First, we will describe the SRDP measurements that supply important TES operating properties. Second, we will expand upon the ideal TES bolometer theory to develop an extended thermal architecture to model non-ideal behaviors of the ACT TES bolometers, emphasizing a characterization that accounts for both the complex impedance and the noise as a function of frequency