Millimeter Anisotropy eXperiment IMaging Array
The Millimeter Anisotropy eXperiment IMaging Array[1] experiment was a balloon-borne experiment funded by the NSF, NASA and the Department of Energy to measure the fluctuations of the Cosmic microwave background. It absolves 2 flights in Aug 1998 and June 1999, each time the balloon was started from the Columbia Scientific Balloon Facility in Palestine, Texas and flies 40.000 metres high for over 8 hours. While flying it took data from about 0.3 percent of the sky of the nouthern region near the Draco constellation. The second flight, known as MAXIMA-II, twice the area was observed, now in the direction of Ursa Major.
Initially planned together with the BOOMERanG experiment it splitet off during planning phase to take a less risky approach by reducing flying time plus launching and landing on the United States home territory.The experiment involve an international collaboration headed by the University of California
Instrumentation
A 1.3 primary mirror plus a smaller secondary and terrtiary mirror is used to focus the microwaves onto the feed horns. The feed horns have spectral bands centre at 150, 240 and 420 GHz with an resolution of 10 arcminutes. Which further guides them to the bolometer array consisted of 16 bolometers, which were consisted of NTD-Ge Thermistors.
The detector array was cooled down to 100 mK via a four stage refrigeration process. Liquid nitrogen cooled the outer layer of radiation shielding and He-4 was used to cool the two other layers down to a temperature of 2-3 K. Finally liquid He-3 cooled the array down to operation temperature. The shielding together with the properties of the feed horns gave a superb sensitivity of 40 μV/sec^1/2
2 CCD-cameras where used to provide accurate measurements of the telescope's orientation. The first wide-field camera pointed towards Polaris and gave a coarse orientation up to 15 arcminutes. The other camera was mounted in the primary focus and gives an accuracy of 0.5' for stars brighter than the 6 magnitude, which in total gives an accurate position tracking of 10' for the telescope and hence of the microwaves.
For pointing the telescope 4 motors were used.
Results
Compared to MAXIMA's competitor the BOOMERanG experiment, it's data covers a smaller part of the sky but was much more detail. In fact, by the end of the year 2000 the experiment provided the most accurate measurements of the CMB Fluctuations on small angular scales. With this data it is possible to calculate the first three acoustic preaks from the CMB power spektrum. There greatly affirm the standard cosmological model by predicting an baryon density of about 4%, which is in great confidence with the density calculated from the Big Bang nucleosynthesis. They also predicte the flatness of the universe which strenghten the inflation theory.
References
- ^ "MAXIMA Press Release". UC Berkeley. 2000-04-09. Retrieved 2007-05-01.
See also
External links
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