My Ph.D. thesis project was QUIET (the Q/U Imaging ExperimenT). QUIET consisted of two separate focal plane arrays of pseudo-correlation polarimeters, one operating at 40 GHz and the other at 90 GHz, observing sequentially from a 1.4 meter telescope located at the Chajnantor Observatory in the Atacama desert of Chile. The detector design incorporates MMIC (Monolithic Microwave Integrated Circuit) amplifiers into a compact “polarimeter on a chip” capable of simultaneously measuring the Q and U Stokes parameters that describe linear polarization.

The QUIET 40 GHz receiver contained 19 detector modules—17 configured as polarimeters and two configured for a differential temperature measurement. It operated from October 2008 through June 2009. The QUIET 90 GHz receiver contained 90 detector modules—84 polarimeters and six differential temperature modules. It operated from August 2009 through December 2010. The two QUIET receivers placed constraints on the amplitude of the BB spectrum in the low-ℓ range, just short of the best constraints at the time from BICEP1. Notably, QUIET demonstrated extremely tight control of systematic errors, with sources of false B-mode polarization at ℓ~100 estimated to be below the r=0.01 level for the 90 GHz instrument.

My work on QUIET spanned from the early days of individual module testing through integration of the 90 GHz array and field operations of both receivers. Data analysis efforts included extracting instrument calibration parameters from astronomical observations, CMB data selection, and analysis validation. As a collaboration, QUIET followed a policy of blind analysis, proceeding through many iterations of refinement and checks before we “opened the box” on the final result.

QUIET Publications

  • Ruud et al. (2015), The Q/U Imaging Experiment: Polarization Measurements of the Galactic Plane at 43 and 95 GHz, ApJ, 811, 2, 89 [ADS, arXiv:1508.02778]
  • Huffenberger et al. (2015), The Q/U Imaging Experiment: Polarization Measurements of Radio Sources at 43 and 95 GHz, ApJ, 806, 1, 112 [ADS, arXiv:1412.1111]
  • QUIET Collaboration (2013), The QUIET Instrument, ApJ, 768, 1, 9 [ADS, arXiv:1207.5562]
  • QUIET Collaboration (2012), Second Season QUIET Observations: Measurements of the Cosmic Microwave Background Polarization Power Spectrum at 95 GHz, ApJ, 760, 2, 145 [ADS, arXiv:1207.5034]
  • QUIET Collaboration (2011), First Season QUIET Observations: Measurements of Cosmic Microwave Background Polarization Power Spectra at 43 GHz in the Multipole Range 25 ≤ ℓ ≤ 475, ApJ, 741, 2, 111 [ADS, arXiv:1012.3191]