Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 2006
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006aas...20924002f&link_type=abstract
2007 AAS/AAPT Joint Meeting, American Astronomical Society Meeting 209, #240.02; Bulletin of the American Astronomical Society,
Astronomy and Astrophysics
Astronomy
Scientific paper
The ARCADE II instrument was designed to compare the cosmic microwave background spectrum to a blackbody spectrum at long (cm) wavelengths where the first stars are predicted to distort the ideal spectrum of the big bang. Reionization generates larger relative distortions at low frequencies. ARCADE II observed at 5 frequencies (3, 8, 10, 30 & 90 GHz). Each radiometer has a corrugated feed horn, a Dicke switch, internal calibrator, and amplifier mounted in an open liquid helium Dewar. The Dewar is 1.5 m in diameter and 1.8 m deep.
The ARCADE II employs a double difference scheme to control systematic errors, similar to the design of the COBE FIRAS instrument. The input to each radiometer is switched at 75 Hz between its internal calibrator and its horn antenna. The horn can observe either the sky or an external calibrator which is temperature controled to match the temperature of the CMB.
Detailed thermal charactorization of the external calibrator is enabled by 35 RuO thermometers embedded in the calibrator. The external calibrator has demonstrated 2.725 K operation even in the residual atmosphere at balloon altitudes.
The ARCADE II was launched on a balloon from Palestine TX on 2006 July 28. Approximately 3 hours of data were obtained, at 115000 feet, that allow calibration of the instrument and precise measurements of the spectrum of the CMB down to 3 GHz. The 12 degree beams of the radiometers were swept across the sky to show the Galaxy as well as the CMB. Pictures taken in flight show that cryogenic surfaces open to the sky can remain relatively frost free for hours with proper helium gas flow.
Fixsen Dale J.
Kogut Alan
Levin Sergey
Limon Michele
Lubin Philip
No associations
LandOfFree
Preliminary Results from ARCADE II does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Preliminary Results from ARCADE II, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Preliminary Results from ARCADE II will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-960208