The design of the Ali CMB Polarization Telescope receiver
  Ali CMB Polarization Telescope (AliCPT-1) is the first CMB degree-scale
polarimeter to be deployed on the Tibetan plateau at 5,250m above sea level.
AliCPT-1 is a 90/150 GHz 72 cm aperture, two-lens refracting telescope cooled
down to 4 K. Alumina lenses, 800mm in diameter, image the CMB in a 33.4{\deg}
field of view on a 636mm wide focal plane. The modularized focal plane consists
of dichroic polarization-sensitive Transition-Edge Sensors (TESes). Each module
includes 1,704 optically active TESes fabricated on a 150mm diameter silicon
wafer. Each TES array is read out with a microwave multiplexing readout system
capable of a multiplexing factor up to 2,048. Such a large multiplexing factor
has allowed the practical deployment of tens of thousands of detectors,
enabling the design of a receiver that can operate up to 19 TES arrays for a
total of 32,376 TESes. AliCPT-1 leverages the technological advancements in the
detector design from multiple generations of previously successful
feedhorn-coupled polarimeters, and in the instrument design from BICEP-3, but
applied on a larger scale. The cryostat receiver is currently under integration
and testing. During the first deployment year, the focal plane will be
populated with up to 4 TES arrays. Further TES arrays will be deployed in the
following years, fully populating the focal plane with 19 arrays on the fourth
deployment year. Here we present the AliCPT-1 receiver design, and how the
design has been optimized to meet the experimental requirements.
