The Primordial Inflation Polarization Explorer (PIPER)

Understand

The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne cosmic microwave background (CMB) polarimeter designed to search for evidence of inflation by measuring the large-angular scale CMB polarization signal.

• BICEP2 recently reported a detection of B-mode power corresponding to the tensor-to-scalar ratio r = 0.2 on ~2 degree scales.
• If the BICEP2 signal is caused by inflationary gravitational waves (IGWs), then there should be a corresponding increase in B-mode power on angular scales larger than 18 degrees.
• PIPER is currently the only suborbital instrument capable of fully testing and extending the BICEP2 results by measuring the B-mode power spectrum on angular scales $\theta$ = ~0.6 deg to 90 deg, covering both the reionization bump and recombination peak, with sensitivity to measure the tensor-to-scalar ratio down to r = 0.007, and four frequency bands to distinguish foregrounds.