Optimizing Feedhorn-Coupled TES Polarimeters for Balloon and Space-Based CMB Observations
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Maximizing the sensitivity of balloon-based and space-based observations of the cosmic microwave background (CMB) requires detectors with substantially lower saturation power and background noise than ground-based observations, because of reduced atmospheric loading and lower photon noise. We have fabricated and tested prototype transition-edge sensor (TES) bolometers that have architecture identical to that used in feedhorn-coupled TES polarimeter arrays developed for ground-based CMB observations, but have saturation power appropriate for balloon-based or space-based observations (0.5 pW–7 pW). The operating resistance of these bolometers (∼3 mΩ) is appropriate for readout with time-division or gigahertz frequency-division SQUID multiplexers. Dark bolometer measurements show that the noise levels are near the expected thermal-fluctuation-noise background (<10−17 W/Hz1/2), that the thermal response times are faster than the observation requirements, and that low-frequency 1/f noise can be strongly suppressed to <10 mHz by pair differencing. We report on the performance of the prototype devices and progress towards optimizing them for balloon-based and spaced-based observations.
KeywordsBalloon Cosmic microwave background Feedhorn Low-frequency noise Polarization Satellite Transition-Edge Sensor
We thank NIST, NASA, and members and supporters of the TRUCE collaboration. Niemack was supported in part by a National Research Council Postdoctoral Fellowship.
- 1.CMBpol Mission Concept Study Group and the Primordial Polarization Program Definition Team, CMBpol Mission Concept Study Report for the Astro2010 Decadal Committee on Astrophysics (2009) Google Scholar
- 2.K. Smith et al., CMBPol mission concept study: gravitational lensing (2009). arXiv:0811.3916
- 3.J. Bock et al., EPIC-IM Overview. CMBPol Workshop Presentation (2009). http://cmbpol.uchicago.edu/workshops/path2009/abstracts.php#54
- 4.Cosmic Origins Explorer, European Space Agency White Paper (2011) Google Scholar
- 5.K.-W. Yoon et al., Feedhorn-coupled TES polarimeters for next-generation CMB instruments. Proc. LTD-13 1185, 515–518 (2009) Google Scholar
- 6.J. Hubmayr et al., An all silicon feedhorn-coupled focal plane for CMB polarimetry. J. Low Temp. Phys. (2012). doi: 10.1007/s10909-011-0420-7
- 8.J.J. McMahon et al., SPTpol: an instrument for CMB polarization. Proc. LTD-13 1185, 511–514 (2009) Google Scholar
- 10.K. Irwin, G. Hilton, Transition-Edge Sensors, in Cryogenic Particle Detection, ed. by C. Enss (Springer, Berlin, 2005) Google Scholar
- 11.J.P. Nibarger et al., An 84 pixel all-silicon corrugated feedhorn for CMB measurements. J. Low Temp. Phys. (2012). doi: 10.1007/s10909-011-0428-z
- 12.J.J. McMahon et al., Multichroic feedhorn-coupled TES polarimeters. J. Low Temp. Phys. (2012) Google Scholar
- 14.J.A. Mates, The Microwave SQUID Multiplexer. PhD thesis, University of Colorado, Boulder, USA, 2011 Google Scholar