Solving a Cosmic Ray Conundrum
Science Magazine April 12, 2008Astronomers say they have solved a puzzle about the most energetic particles that smash into Earth. Known as ultrahigh-energy cosmic rays, these particles, mostly protons, each pack as much punch as a fast-pitched baseball.
According to a theory first proposed 42 years ago, the particles ought to rarely reach Earth with the particles ought to rarely reach Earth with such high energies because many lose about 20 percent of their energy when they collide with photons from the cosmic microwave background - the Big Bang's afterglow.
read moreUltrahigh-energy Cosmic Rays Are From Extremely Far Away
Science Daily March 25, 2008Final results from the University of Utah's High-Resolution Fly's Eye cosmic ray observatory show that the most energetic particles in the universe rarely reach Earth at full strength because they come from great distances, so most of them collide with radiation left over from the birth of the universe.
The findings are based on nine years of observations at the now-shuttered observatory on the U.S. Army's Dugway Proving Ground. They confirm a 42-year-old prediction - known as the Greisen-Zatsepin-Kuzmin (GZK) "cutoff," "limit" or "suppression" - about the behavior of ultrahigh-energy cosmic rays, which carry more energy than any other known particle.
read more"Little" Cosmic Ray Observatory Aims to Make a Big Mark
Science Magazine January 27, 2008In a field in which bigger is usually better, what can you hope to achieve with a new experiment that's only a quarter as large as its well-established rival? Plenty, say 117 physicists mainly from Japan and the United States who have just started taking data with a cosmic ray observatory that covers 730 square kilometers of western Utah.
Dubbed Telescope Array, the observatory aims to spot the most energetic subatomic particles from space. Such ultrahigh-energy cosmic rays pack as much energy as a golf ball hitting a fairway, and they strike Earth at a rate of 1 per century per square kilometer. Interest in them grew 10 years ago, when Japanese physicists reported an odd excess of the highest energy rays. It surged last year, when the gargantuan Pierre Auger Observatory in Argentina traced the rays to certain galaxies (Science, 9 November 2007, p. 896).
Tracing Cosmic Bullets
Science Magazine December 21, 2007What's smaller than an atom but crashes into Earth with as much energy as a golf ball hitting a fairway? Since the 1960s, that riddle has tantalized physicists studying the highest energy cosmic rays, particles from space that strike the atmosphere with energies 100 million times higher than particle accelerators have reached. This year, the Pierre Auger Observatory in Argentina supplied key clues to determine where in space the interlopers come from.
read moreCosmic Ray Scientists Awarded
University of Utah News October 3, 2007Three University of Utah physicists have won prestigious prizes from the American Physical Society. Professors GEORGE CASSIDAY and PIERRE SOKOLSKY, who also is dean of the College of Science, will share the $10,000, 2008 W.K.H. Panofsky Prize in Experimental Particle Physics. They were cited for pioneering development of a method to study ultrahigh-energy cosmic rays by detecting faint, fluorescent, ultraviolet flashes that occur when incoming cosmic ray particles collide with gases high in Earth's atmosphere. The method was used at the university's now-shuttered Fly's Eye and High-Resolution Fly's Eye cosmic ray detectors at Dugway Proving Ground, and at the new Telescope Array cosmic ray observatory near Delta, Utah.
read moreEnormous Detector Forces Rethink Of Highest Energy Cosmic Rays
ScienceNOW Daily News July 13 2007MERIDA, MEXICO--When, a decade ago, physicists in Japan reported seeing far more ultrahigh-energy cosmic rays than expected, some theorists interpreted the excess as a hint of exotic new particles--perhaps supermassive relics from the big bang that could be part of the mysterious dark matter whose gravity holds the galaxies together. But the controversial excess of super-energetic particles from space has a simpler explanation, researchers with a far larger detector array now say: It doesn't exist.
read moreA Comedown For Cosmic Rays
ScienceNOW Daily News July 3 2007MERIDA, MEXICO--An otherwise inexplicable excess in the highest energy cosmic rays crashing into Earth has been explained in the simplest way: The excess simply doesn't exist. The new result may disappoint physicists who had perceived hints of exciting new phenomena in the overabundance of individual subatomic particles cruising along with as much energy as a large hailstone. It also leaves some mysteries unanswered. Really energetic particles should hit Earth only very rarely. After all, the number of cosmic rays pelting Earth decreases steadily as the energy of the rays increases. Above a specific energy, the rate ought to drop even faster. For example, if the rays consist mainly of protons, then at such tremendous energies they ought to break into other subatomic particles when they collide with photons in the afterglow of the big bang, the cosmic microwave background...
read moreFly's Eye Group Reports Seeing the Predicted Ultrahigh-Energy Cutoff of the Cosmic-Ray Spectrum
Physics Today May 2007The flux of ultrahigh-energy cosmic rays is very small, and it falls steeply with increasing energy. From 1016 to 1019eV, the flux falls roughly like E-3, where E is the energy of the primary cosmic-ray particle (most likely a proton from an extragalactic source) hitting the top of the atmosphere. Even if the E-3 falloff continues indefinitely, one would see only a few dozen comic rays per square kilometer per century with energies above 1019eV. Thatʼs why observers studying ultra-high-energy cosmic rays want detection facilities with effective areas of thousands of square kilometers (see the article by Thomas OʼHalloran, Pierre Sokolsky, and Shigeru Yoshida in PHYSICS TODAY, January 2008, page 31).
read moreAll 485 Surface Detectors on BLM Land Deployed
The placement of the 485 surface detectors on public lands has been completed February 28 by the Telescope Array group. This was an intensive effort that began last fall and involved large numbers of scientists from Japan, Korea, and the U.S.
Pierre Sokolsky Awarded Governor's Medal
Pierre Sokolsky, principle investigator of the Telescope Array Project, has been awarded the Governor's Medal of Science and Technology.
Ground Array Deployment
An additional 24 detectors were deployed via helecopter.
Black Rock Mesa Tower Construction
We started the communication tower at Black Rock Mesa on September 15th (Fri) and finished the construction on September 16th (Sat).
We will move to Long Ridge site on September 18th (Mon).
