BOOMERanG experiment

The BOOMERanG experiment (short for "Balloon Observations Of Millimetric Extragalactic Radiation and Geophysics " - Balloon observations of extragalactic millimeter radiation and for Geophysics ) measured the properties of the cosmic background radiation during three balloon flights. It succeeded for the first time to hold reliable and detailed pictures of the tiny temperature fluctuations of this radiation. The reason for the use of a balloon was the fact that the microwave radiation to be measured is absorbed by the atmosphere for the most part. The balloon -based observations found around 42 kilometers above the ground instead, at an altitude where the microwave radiation have been well demonstrated. The use of a balloon is markedly cheaper than a satellite mission; However, there was the disadvantage that it is only a small section of the sky could be observed.

The first test flight took place over North America in 1997. The next two flights in 1998 and 2003 began at the McMurdo Station in Antarctica, respectively. There, the polar vortex ensures that the balloon after about two weeks returns to his starting point - like the Australian boomerang, from which the name of the experiment is derived.

Instruments

The telescope of BOOMERanG has a mirror with 1.2 meters in diameter, which focuses the microwaves in the focal plane. There sit 16 antenna horns, which divide the field of view in eight by two pixels. Accordingly, it can be observed at any time only a tiny section of sky; scan around the observed region of the sky, the entire telescope must be rotated.

Core of BOOMERanG are special bolometers for the detection of microwave radiation. The bolometers are cooled to a temperature of 0.27 kelvin. Debye model suggests that the material has a very low heat capacity at such low temperatures. Therefore Incident microwaves lead to significant temperature increase proportional to the intensity of the incoming radiation. The temperature change is detected by highly sensitive thermometers.

Results

From the BOOMERanG data from 1997 and 1998, together with the measurements of experiments such as Saskatoon, TOCO and MAXIMA, important characteristics of the fluctuations of the cosmic background radiation revealed. Combining these data with that determined by other measurements value of the Hubble constant, one can conclude that the universe has a flat, Euclidean geometry. This supports the result of supernova observations, which point to an accelerated expansion of the universe and the existence of so-called dark energy. The 2003 the second South Pole flight showed a map of temperature fluctuations which had a significantly better signal -to-noise ratio. In addition, the polarization of the background radiation is measured.