|DLS: SPT is blocking the sun, and BICEP2 is to the far right|
|In this case, no light will be transmitted through the second|
polarizer, much like if you orient the lenses of two pair of
polarized sunglasses perpendicular to each other, no light
will get through.
|The CMB. The different colors represent different temperatures.|
The coldest areas are dark blue, while the warmest are red. The circle
highlights a particularly large and cold region that was studied at the
BICEP2 is also a millimeter/sub-millimeter telescope studying the CMB. It this case, however, BICEP2 is looking at the CMB in order to explore the conditions in the universe in the earliest times after the Big Bag. The CMB is the result of photons produced when the universe cooled enough to allow electrons to combine to form hydrogen (~380,000 years after the Big Bang), making the CMB the oldest light in the universe, and thus, a very powerful tool for probing the universe at these early times. One of the theories of what happened immediately after the Big Bang, is that the universe underwent a period of rapid expansion called Inflation. If this did in fact occur, it would produce something called the Cosmic Gravitational-Wave Background, which in turn would have left a faint signature in the polarization of the CMB. It is this signature that BICEP2 (512 detectors), and its predecessor BICEP1(98 detectors), are searching for.
|The optics and detector of BICEP. The 4-tile focal plane unit is where|
the detectors are located. The 512 detectors of BICEP2 are divided
amongthree of these BICEP2/Keck inserts.
My role in all this is delivering the helium that keeps the optics and detectors on BICEP2 cool. The optics are kept at a temperature of 4K, four degrees above absolute zero. The detectors are kept evern cooler, at 250mK. This reduces the amount of electron noise in the detectors, allowing them to more sensitively and accurately detect that signature they are looking for.
In the case of both BICEP2 and SPT, they were built at the South Pole for a very specific reason. It is extremely dry here. Water vapor in the atmosphere absorbs millimeter and sub-millimeter wave lengths, making it difficult to observe the CMB in most places. The combination of altitude (almost 11,000 ft) and cold temperatures make for a very dry atmosphere. As an added bonus, night lasts for months here. The lack of daily sunrises/sunsets make for an extremely stable atmosphere, and allow for extended observations that would otherwise be interrupted by the sun.
|A couple more pretty pictures of DSL|
If you'd like to learn more about BICEP2 and SPT, these are some good places to start: