B mode from Space -- Part 1: The Science goals, status of spaceborne projects, foregrounds (Dec 10 -12), Part 2: Mission design, technologies and challenges for the spaceborne observations (Dec 14 -16) --

A population of aligned, aspherical grains will emit linearly polarized radiation from infrared to microwave wavelengths. I will review the physics of dust polarization, focusing on the factors that determine the level and frequency dependence of the infrared and microwave emission, such as magnetic field geometry, depolarization, and the relative contribution of various grain materials to the total emission. Particular emphasis will be given to uncertainties in current dust models and the adequacy of simple parametric fits to the polarized dust SED.

The Primordial Inflation Polarization ExploreR (PIPER) is a balloon-borne instrument being developed at NASA Goddard. It will measure the CMB polarization at 200, 270, 350, and 600 GHz across 85% of the sky, seeking the B-mode signature of inflationary gravitational waves on large angular scales. It employs a Continuous Adiabatic Demagnetization Refrigerator (CADR) to cool its detectors to 100 mK. The CADR architecture is robust (solid-state), stable, and efficient, so is of great interest to future CMB missions. I will describe PIPER's CADR, its thermodynamics, and hardware with contrast to single-shot coolers. Magnetic fields and temperature stability are key instrumental constraints for PIPER's Transition-edge superconducting detectors and readout chain. I will describe recent operation of the CADR, its characterization, stability and magnetic fields.

I will give overview of a focal plane unit proposed by the US LiteBIRD team. The focal plane unit consists of sub-kelvin cooler, transition edge sensor bolometric detector, readout electronics, and mechanical supports. The baseline design is based on proven technologies from current ground and balloon based CMB experiments lead by member of the US LiteBIRD team. Space environment and sensitivity target of the LiteBIRD mission introduces challenges that need to be carefully studied and tackled. Organization of the group and the status will be presented.

The Planck satellite mission allowed to map the Cosmic MicrowaveBackground anisotropies and polarization on the full sky withunprecedented accuracy. The precision of the measurements was reachedthanks to the thermal stability of the instruments which includePolarization Sensitive Bolometers cooled down to 100 mK for the HighFrequency Instrument, but required carefull processing of systematicspresent in data. I will review the main sources of systematics relatedto Planck HFI detectors and the main difficulties encountered tocharaterize and process them. Some of those effects were not expectedbefore the flight. The main effects include the cosmic ray interactionwith detectors, long time constants, analog to digital convertornon-linearities, band pass mismatch, as well as 1/f noise.

We discuss one of the two candidate detector technologies for the LiteBIRD satellite mission: lenslet-coupled sinuous antenna transition edge sensor (TES) detector arrays. We discuss the current status and future challenges for the design, fabrication, and characterization of this technology for the LiteBIRD low and mid frequency (LF and MF, respectively) focal planes. These design of these devices was developed by UC Berekeley and the first LiteBIRD LF prototype detectors were recently fabricated there as well. In addition to the development of this technology for LiteBIRD, both the POLARBEAR-2 and SPT-3G collaborations will deploy focal planes composed of multi-chroic lenslet coupled sinuous antenna detectors in the next year and half. Despite the strong legacy of these detectors there exists many challenges to reliably engineer these devices for a satellite mission. The focus of this talk will be on building a robust and repeatable fabrication process, the tailoring of these detectors for lower optical loading, and accurately tuning the bands (including notch filters to avoid CO lines) to meet the specifications of the LiteBIRD mission. In addition to these tasks we will report on a study of the effects of high energy cosmic rays we expect in a space environment on the performance of this technology.

I will discuss technology developed and fabricated at NIST that is relevant to the LiteBIRD satellite mission. This includes feedhorn-coupled, transition-edge-sensor (TES) polarimeter arrays, which are the baseline focal plane technology of the high frequency telescope as proposed in the US-contribution to the mission. Developed in collaboration with a large fraction of the US CMB community, feedhorn-coupled TES polarimeter arrays have been utilized in the South Pole Telescope Polarimeter (SPTpol) and the Atacama Cosmology Telescope Polarimeter (ACTPol). I will present an overview of the architecture; review on-sky performance; detail recent developments such as multichroic detector development on 150mm substrates for Advanced ACTPol and the production of 300 GHz arrays for the second flight of SPIDER; and comment on how to adapt the arrays for a space mission. Additionally, I will review SQUID-based multiplexer components designed and fabricated at NIST, which in the last decade have enabled over 30,000 mm/sub-mm bolometers to observe the sky from platforms around the world.

The design of the LiteBIRD focal planes needs to balance cryogenic, mechanical, optical and electrical concerns. I will discuss the cryogenic and mechanical issues associated with these technologies with special emphasis on the unique challenges and uncertainties present in a space-based environment. Additionally, I will summarize baseline technologies and the requirements for the LiteBIRD sub-Kelvin cooler.

The Digital Frequency Domain Multiplexing Bolometer Readout system is the baseline design for LiteBIRD. The overall system will be presented, with a focus on the warm electronics. The cold components will be described in the following talk. Results and status from Canadian-funded flight representative circuit board development will be overviewed.Key interface points, power consumption, and challenges that lay ahead to achieve the mission specifications will be summarized.

will present the baseline architecture for all of the electrical components between the LiteBIRD detector wafers and the warm readout electronics. This baseline architecture is based on the requirements of the frequency domain multiplexing bolometer readout, which will be discussed by Professor Dobbs in the previous presentation. I will discuss the requirements that still need to be determined for these components, and the design decisions that these requirements still need to inform. I will discuss the POLARBEAR / Simons Array experience, and where I think the most significant component modification will be necessary from the hardware used in those instruments. This will lead into the discussion of SQUID requirements and design, which will be the topic of the following presentation by Professor Irwin.