My research has developed measurement tools for the far infrared to millimeter wave spectral range and used these tools to work on the most interesting accessible physical problems. I retired in 2004 and now hold an appointment as Professor of the Graduate School at Berkeley. I continue to work with the group that I started in 1966, which is now led by Professor Adrian Lee.
The Lee/Richards group has developed superconducting transition edge bolometers with SQUID readouts. We have produced arrays of such bolometers by optical lithography and developed multiplexed readouts to minimize the number of amplifiers required. Receivers with arrays of up to 1000 bolometers have been deployed on the APEX-SZ telescope in Chile and the South pole Telescope where they are being used to map the sky at millimeter wavelengths to search for clusters of Galaxies using the Sunyaev-Zeldovich effect. The goal is to provide a catalog of many thousands of such clusters with redshifts and mass estimates. Such data will enable studies of dark energy and the development of structure in the universe.
The polarization anisotropy of the CMB is expected to provide evidence for the emission of gravity waves at the time of inflation and test cosmological models on the GUT energy scale. The Lee/Richards group is developing arrays of antenna coupled dual polarization bolometers for such measurements. In collaboration with the University of Minnesota, the MAXIPOL balloon measurement of the polarization anisotropy of the CMB has just been completed. A very powerful ground based polarization anisotropy experiment called Polar BEAR is under construction, which will be fielded first in California and then in Chile.
S. Hanany, P. Ade, A. Balbi, J. Bock, J. Borrill, A. Boscaleri, P. de Bernardis, P.G. Ferreira, V.V. Hristov, A.H. Jaffe, A.E. Lange, A.T. Lee, P.D. Mauskopf, C.B. Netterfield, S. Oh, E. Pascale, B. Rabii, P.L. Richards, G.F. Smoot, R. Stompor, C.D. Winant, J.H.P. Wu, MAXIMA-1: A Measurement of the Cosmic Microwave Background Anisotropy on Angular Scales of 10' to 5°, Ap. J. Lett.545, L5 (2000).
J. Zmuidzinas and P.L. Richards. Superconducting detectors and mixers for millimeter and submillimeter astrophysics. Proc. IEEE 92, 1597-1616 (2004).
M.J. Myers, P. Ade, G. Engargiola, W. Holzapfel, A.T. Lee, R. O’Brient, P.L. Richards, A. Smith, H. Spieler, and H. Tran. Antenna-coupled bolometer arrays using transition-edge sensors. In Millimeter and Submillimeter Detectors for Astronomy II, J. Zmuidzinas, W.S. Holland, and S. Withington (eds.). Proc. SPIE, Vol. 5498, pp. 95-102 (2004).
P.L. Richards and C.R. McCreight. Infrared detectors for astrophysics. Physics Today 58, 41 (2005).
T.M. Lanting, H.-M. Cho, J. Clarke, W.L. Holzapfel, A.T. Lee, M. Lueker, P.L. Richards, M.A. Dobbs, H. Spieler, and A. Smith. Frequency-domain multiplexed readout of transition-edge sensor arrays with a superconducting quantum interference device. Appl. Phys. Lett. 86, 112511 (2005).
M.J. Myers, W. Holzapfel, A.T. Lee, R. O’Brient, P.L. Richards, H.T. Tran, P. Ade, G. Engargiola, A. Smith, and H. Spieler. An antenna-coupled bolometer with an integrated microstrip bandpass filter. Appl. Phys. Lett. 86, 114103 (2005).
M. Dobbs et al., “APEX-SZ First Light and Instrument Status,” New Astronomy Reviews 50, 960 (2006).