SCIENCE ILLUSTRATED; Trolling for Cosmic Particles Amid the Fish and Shipwrecks
By FRANK O'CONNELL
Published: June 13, 2006
An international group of scientists is building a new kind of telescope at the bottom of the Mediterranean Sea, near the coast of France. To be completed in 2007, it will detect light generated by neutrinos, the high-energy cosmic particles that pass directly through the Earth. Because neutrinos pass through most matter (including the seafloor), scientists can use them to peer into active galactic nuclei. Why underwater? To help shield the telescope from cosmic radiation coming from above. FRANK O'CONNELL
AN UNDERWATER ARRAY
Twelve vertical lines, each made up of 75 optical modules.
Diagram (schematic, not to scale) highlights the following:
3 OPTICAL MODULES
FROM SOURCE TO DETECTION
1. Some neutrinos are thought to be created and ejected into space from black holes.
2. Neutrinos encountering the Earth pass right through, emerging on the other side.
3. Interacting with the Earth's crust or the water of the ocean, the neutrinos produce muons.
4. As they rise up from the ocean floor, the muons emit a faint bluish light, called Cherenkov light.
5. Photo detectors sense this light and relay the data to shore.
As the muons pass through the telescope, individual sensors pick up the emitted light. Tracing the path backward through the array, scientists can determine the particles' trajectory.
Pressure-resistant glass spheres encase photo sensors. The modules are angled down 45 degrees to better detect the muons as they move upward.
Antares observes space by looking down through the Earth rather than up through the atmosphere.
Generated when charged particles travel through a medium faster than light, which slows down in water.
Diagrams highlight the following:
(Source by Antares Collaboration)