TO CATCH A COSMIC RAY

摘要

The tank looks oddly out of place here on the windy Pampas of western Argentina. Surrounded by yellow grass and spiky thorn bushes, the chest-high plastic cylinder could be some kind of storage container -were it not for the bird-spattered solar panels and antennas on top. More tanks can be seen in the distance, illuminated by a crimson Sun dropping behind the far-off Andes. "Some locals think that the tanks influence the weather: they make it rain or snow, or make a dry season," says Anselmo Francisco Jake, the farmer who owns this stretch of land. "But I know they don't. I know they catch cosmic rays." Jake is right. There are 1,600 of these tanks, spaced over a 3,000-square-kilometre expanse that could fit all of Luxembourg with room to spare. Together they comprise the Pierre Auger Observatory: a US$53-million experiment to reveal the mysterious origins of ultra-high-energy cosmic rays, the most energetic subatomic particles known to exist.