The Primordial Inflation Polarization Explorer (PIPER)

TL;DR

PIPER is a balloon-borne telescope designed to measure the polarization of the Cosmic Microwave Background to constrain early universe models, utilizing advanced cryogenic and polarization modulation technologies.

Contribution

This paper introduces the design and current status of PIPER, a novel balloon-borne instrument with advanced polarization measurement capabilities for CMB studies.

Findings

First science flight planned from the Northern hemisphere.

Expected sensitivity to tensor-to-scalar ratio of r ~ 0.007.

Overlap with the CLASS survey for complementary measurements.

Abstract

The Primordial Inflation Polarization ExploreR (PIPER) is a balloon-borne telescope designed to measure the polarization of the Cosmic Microwave Background on large angular scales. PIPER will map 85% of the sky at 200, 270, 350, and 600 GHz over a series of 8 conventional balloon flights from the northern and southern hemispheres. The first science flight will use two 32x40 arrays of backshort-under-grid transition edge sensors, multiplexed in the time domain, and maintained at 100 mK by a Continuous Adiabatic Demagnetization Refrigerator. Front-end cryogenic Variable-delay Polarization Modulators provide systematic control by rotating linear to circular polarization at 3 Hz. Twin telescopes allow PIPER to measure Stokes I, Q, U, and V simultaneously. The telescope is maintained at 1.5 K in an LHe bucket dewar. Cold optics and the lack of a warm window permit sensitivity at the sky-background limit. The ultimate science target is a limit on the tensor-to-scalar ratio of r ~ 0.007, from the reionization bump to l ~ 300. PIPER's first flight will be from the Northern hemisphere, and overlap with the CLASS survey at lower frequencies. We describe the current status of the PIPER instrument.