March 25, 2009

UK-Constructed Receivers To Be Sent To Alma Telescope

Europe is sending its first home-built receiver to the largest radio telescope array ever constructed, nestled in its permanent home in Chile, BBC News reported.

The Atacama Large Millimeter Array (Alma) is made up of sixty six 39-foot wide antenna dishes that detect the faint signals in the sub-millimeter wavelength range to learn more about the formation of stars and galaxies.

Scientists at the Rutherford Appleton Laboratory (RAL) in Oxfordshire will assemble and test 26 of the receivers once the first ones reach the Alma site on Saturday.

Mark Harman, technical manager for the receiver project at RAL, a laboratory of the Science and Technology Facilities Council, said observing sub-millimeter waves will allow scientists to see parts of the universe that are obscured by dust.

Harman said that while the Hubble telescope has an impressive resolution, it couldn't see the sub-millimeter radiation from behind dust clouds.

With help from North America, East Asia, and Europe, the more than one billion dollar Alma collaboration is being overseen by the European Southern Observatory.

The Alma's "outer ear" is made up of super-precise antenna dishes that collect and focus the faintest signals from some of the oldest galaxies in the Universe.

However, the three-quarter ton receivers act as the high-sensitivity "eardrums" that will measure the signals. Each superconducting receiver is cooled to -452F to increase sensitivity.

Gie Han Tan, who is a project manager for the European contingent of Alma receivers, called it a "major step forward" for the Alma project.

"This is really exciting for us," said Tan. "It's a collaboration between three continents from more than 10 sites, and this is the first one from Europe that will go into a full production run."

Alma carefully mixes the signals from each telescope in the 66-strong array in an approach called interferometry, which creates the telescopes unprecedented resolution.

Should observations require a wide field of view or super-high resolution, the 100-ton antennas can be individually moved by truck throughout the year.

The observatory's Operations Support Facility, a base camp at an altitude of 9,500 feet, is already assembling one integrated antenna/receiver system.

A truck will transport the first single system up to the array's site at an altitude of over 16,000 feet, with the first measurements to begin in June.

By September, the Alma team will integrate three of the receiver systems and begin interferometry tests.

RAL is one of the three central engineering control points for the Alma receivers.

The component parts from the UK, mainland Europe and North America will be assembled and rigorously tested before the final product ships out to Chile.

RAL will also be producing the laser-based timing systems for the interferometry. It said the comparison of signals arriving at different times depends crucially on precisely timing each one.


Image Caption: A vision of the near-future ALMA antenna array once it's completed. (C) ESO


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