The E and B Experiment
Encyclopedia
The E and B Experiment will measure the cosmic microwave background radiation
of a part of the sky during two sub-orbital (high altitude
) balloon
flights. It is an experiment to make large, high-fidelity images of the CMB polarization anisotropies. By using a telescope which flies at over 42,000 metres high, it is possible to reduce the atmospheric absorption of microwaves to a minimum. This allows massive cost reduction compared to a satellite probe, though only a small part of the sky can be scanned and for shorter duration than a typical satellite mission such as WMAP.
The first flight was a test flight over North America
in 2009. In the subsequent flight in 2011, the balloon will be launched at the McMurdo Station
in the Antarctic. It will use the Polar vortex
winds to circle around the South Pole
, returning after two weeks.
and a fixed wire grid polarizer. The wire grid is mounted at 45 degrees to the incoming light beam and transmits one polarization state while reflecting the other. Each polarization state is subsequently detected by its own focal plane with a 6 degree instantaneous field-of-view on the sky.
Cosmic microwave background radiation
In cosmology, cosmic microwave background radiation is thermal radiation filling the observable universe almost uniformly....
of a part of the sky during two sub-orbital (high altitude
High altitude balloon
High-altitude balloons are unmanned balloons, usually filled with helium or hydrogen that are released into the stratosphere, generally reaching between ....
) balloon
Balloon
A balloon is an inflatable flexible bag filled with a gas, such as helium, hydrogen, nitrous oxide, oxygen, or air. Modern balloons can be made from materials such as rubber, latex, polychloroprene, or a nylon fabric, while some early balloons were made of dried animal bladders, such as the pig...
flights. It is an experiment to make large, high-fidelity images of the CMB polarization anisotropies. By using a telescope which flies at over 42,000 metres high, it is possible to reduce the atmospheric absorption of microwaves to a minimum. This allows massive cost reduction compared to a satellite probe, though only a small part of the sky can be scanned and for shorter duration than a typical satellite mission such as WMAP.
The first flight was a test flight over North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
in 2009. In the subsequent flight in 2011, the balloon will be launched at the McMurdo Station
McMurdo Station
McMurdo Station is a U.S. Antarctic research center located on the southern tip of Ross Island, which is in the New Zealand-claimed Ross Dependency on the shore of McMurdo Sound in Antarctica. It is operated by the United States through the United States Antarctic Program, a branch of the National...
in the Antarctic. It will use the Polar vortex
Polar vortex
A polar vortex is a persistent, large-scale cyclone located near one or both of a planet's geographical poles. On Earth, the polar vortices are located in the middle and upper troposphere and the stratosphere...
winds to circle around the South Pole
South Pole
The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earth's axis of rotation intersects its surface. It is the southernmost point on the surface of the Earth and lies on the opposite side of the Earth from the North Pole...
, returning after two weeks.
Instrumentation
EBEX consists of a 1.5 m Dragone-type telescope that provides a resolution of 8 arcminutes in frequency bands centered around 150, 250, and 410 GHz. Polarimetry is achieved with a continuously-rotating achromatic half-wave plate supported by a superconducting magnetic bearingMagnetic bearing
A magnetic bearing is a bearing which supports a load using magnetic levitation. Magnetic bearings support moving machinery without physical contact; for example, they can levitate a rotating shaft and permit relative motion with very low friction and no mechanical wear...
and a fixed wire grid polarizer. The wire grid is mounted at 45 degrees to the incoming light beam and transmits one polarization state while reflecting the other. Each polarization state is subsequently detected by its own focal plane with a 6 degree instantaneous field-of-view on the sky.