If you want to hear a little bit of the Big Bang, you're going to have to turn down your stereo.
That'swhat neighbors of MIT's Haystack Observatory found out. They were askedto make a little accommodation for science, and now the results are in:Scientists at Haystack have made the first radio detection ofdeuterium, an atom that is key to understanding the beginning of theuniverse. The findings are being reported in an article in the Sept. 1issue of Astrophysical Journal Letters.
The team of scientistsand engineers, led by Alan E.E. Rogers, made the detection using aradio telescope array designed and built at the MIT research facilityin Westford, Mass. Rogers is currently a senior research scientist andassociate director of the Haystack Observatory.
After gathering data for almost one year, a solid detection was obtained on May 30.
Thedetection of deuterium is of interest because the amount of deuteriumcan be related to the amount of dark matter in the universe, butaccurate measurements have been elusive. Because of the way deuteriumwas created in the Big Bang, an accurate measurement of deuterium wouldallow scientists to set constraints on models of the Big Bang.
Also,an accurate measurement of deuterium would be an indicator of thedensity of cosmic baryons, and that density of baryons would indicatewhether ordinary matter is dark and found in regions such as blackholes, gas clouds or brown dwarfs, or is luminous and can be found instars. This information helps scientists who are trying to understandthe very beginning of our universe.
Until now the deuterium atomhas been extremely difficult to detect with instruments on Earth.Emission from the deuterium atom is weak since it is not very abundantin space-there is approximately one deuterium atom for every 100,000hydrogen atoms, thus the distribution of the deuterium atom is diffuse.Also, at optical wavelengths the hydrogen line is very close to thedeuterium line, which makes it subject to confusion with hydrogen; butat radio wavelengths, deuterium is well separated from hydrogen andmeasurements can provide more consistent results.
In addition,our modern lifestyle, filled with gadgets that use radio waves,presented quite a challenge to the team trying to detect the weakdeuterium radio signal. Radio frequency interference bombarded the sitefrom cell phones, power lines, pagers, fluorescent lights, TV, and inone case from a telephone equipment cabinet where the doors had beenleft off. To locate the interference, a circle of yagi antennas wasused to indicate the direction of spurious signals, and a systematicsearch for the RFI sources began.
At times, Rogers asked for helpfrom Haystack's neighbors, and in several instances replaced a certainbrand of answering machine that was sending out a radio signal with onethat did not interfere with the experiment. The interference caused byone person's stereo system was solved by having a part on the soundcard replaced by the factory.
The other members of the teamworking with Rogers are Kevin Dudevoir, Joe Carter, Brian Fanous andEric Kratzenberg (all of Haystack Observatory) and Tom Bania of BostonUniversity.
The Deuterium Array at Haystack is a soccer-fieldsize installation conceived and built at the Haystack facility withsupport from the National Science Foundation, MIT and TruePosition Inc.
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