| 27th of October 2017 |
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| EDGES - an Experiment to Detect the Global EoR Signature |
| by Judd Bowman (Arizona State University) |
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The Experiment to Detect the Global Epoch-of-Reionisaton (EoR) Signature
(EDGES) is a radio spectrometer
operated at the Murchison Radio-astronomy Observatory by Arizona State
University and MIT Haystack
Observatory. The experiment aims to detect the global redshifted 21 cm
signature of neutral hydrogen gas in the early Universe due to the formation
of the first stars and subsequent reionization of the intergalactic medium. It
measures the sky-averaged spectrum below 200 MHz using two instruments. Each
instrument consists of a zenith-pointed broadband dipole antenna with smooth
beam properties and a receiver that has been precisely calibrated to 0.1%
absolute accuracy and better than 0.01% relative accuracy across an octave of
bandwidth. Photo caption: Cheap trick! A used brekkie juice bottle protects a capacitive tuning plate on top of the EDGES low-band antenna from condensation and rain water. Excess moisture in narrow gap can change the tuning of the antenna, adversely affecting the sensitive cosmology measurements. |