Benjamin Stokes
For more than 10 years, the vast span of desert west of Delta has been home to more than 500 cosmic ray detectors spaced about two-thirds of a mile apart. There are also three huge observatory buildings containing a total of 38 telescopes. Their segmented mirrors are aimed at the sky, looking for ultrahigh-energy cosmic rays.

DELTA, Millard County — One of the most baffling mysteries of the universe has triggered a major new effort in western Utah — a dramatic expansion of a vast scientific instrument spread across the desert.

"We're going from 300 square miles to 1,200 square miles," said John Matthews, a research professor at the University of Utah and program manager of the Cosmic Ray Physics Group.

Scientists hope the expanded array of cosmic ray detectors will zero in on a possibly violent force in the cosmos and — perhaps — finally explain an astounding observation 25 years ago. That's when scientists in Utah detected a tiny proton that was so incredibly powerful it was dubbed the "Oh My (Gosh)!" particle.

"Yeah, that was the reaction," said University of Utah graduate student Jon Paul Lundquist.

For more than 10 years, the vast span of desert west of Delta has been home to more than 500 cosmic ray detectors spaced about two-thirds of a mile apart. Each one is about the size of a billiard table and has the general appearance of a hospital bed. Helicopters recently flew dozens of additional detectors into place. Researchers hope to raise the number of detectors to about 1,100 in the next couple of years, quadrupling the size of the detector array.

The purpose of the array is to detect showers of subatomic particles raining down from the sky. Cosmic rays trigger the showers when they hurtle into Earth's atmosphere and collide with air molecules.

"There's a cosmic ray track right there," said Lundquist, pointing to a series of blue dots streaking across a display on a computer monitor. Lundquist often spends his nights in the control room of a large observatory building about 20 miles northwest of Delta. Observation doors typically open at sunset, allowing a large bank of telescope mirrors to scan the night sky.

Pointing to the wildly distorted reflections in the mirrors, Lundquist said, "These are the focusing mirrors for light that's caused by cosmic rays in the sky. They hit the atmosphere, they create like a fireworks shower, and that's what we see. That's what we look for, that's what makes the light."

The term "cosmic ray" is actually a misnomer. They are not rays. They are tiny high-speed objects — protons and other subatomic particles — racing toward Earth from outer space. Low-energy cosmic rays hit our atmosphere by the billions every day. All the time. No big deal. Most of them come from the sun.

But every now and then, a few times a year, the detectors have spotted extreme high-energy particles traveling at nearly the speed of light, each one packing incredibly high levels of energy.

"Well, we'd like to be able to figure out where they're coming from and how they get their energy," said Robert Cady, a professor of physics at the University of Utah. "All we know at this point is they're coming from 'out there' someplace."

The granddaddy of them all, a one-of-a-kind, ultra-extreme, high-energy cosmic ray was spotted at Dugway Proving Ground 25 years ago. Back then, for scientists, that one-time-only observation was a sensation. In a 1995 interview, U. physics professor Pierre Sokolsky said: "It would be like someone working with chimpanzees and suddenly a hundred-ton gorilla walks through the door. I mean, you gotta pay attention."

Scientists at first didn't believe it. A tiny object packing a major-league punch. "Much smaller than an atom," Lundquist said, "and yet it had enough energy that it's like a fastball being thrown at your face at 80 miles per hour."

"It's still the record holder for energy," Sokolsky said in a recent interview. "It was dubbed by other people the 'Oh My (Gosh)!' particle'."

A quarter century later that single particle is still unexplained. "We've never seen another one like it," Sokolsky said in a recent interview. "It remains mysterious."

In the last 25 years, the detectors have spotted about 70 more ultrahigh-energy cosmic rays. All are lower in energy — and slower — than the big particle but they are vastly more powerful that the garden-variety cosmic rays emitted by the sun.

Those few dozen ultrahigh energy particles have generated an exciting and baffling mystery for scientists. Researchers simply don't know what objects or processes in deep space are hurling particles toward Earth at such extreme energy levels. That's why they're stepping up the search for more. By quadrupling the size of the detector array from 300 square miles to 1,200 square miles, scientists hope to see ultrahigh-energy cosmic rays far more often.

"Instead of (seeing) a hundred in seven years," Matthews said, "we'll be able to see probably about 500 events in the next few years. So we should be able to really nail down what it is we're looking at."

Three years ago, the researchers determined that many of the most energetic cosmic rays are coming from a "hot spot" in the heavens near the Big Dipper. That raises the possibility that a violent, cataclysmic process — perhaps a collision of black holes — is propelling tiny particles toward Earth with awesome energy. But that leads to the central mystery: zyhere doesn't seem to be anything out there in the direction of the "hot spot" that would explain it.

"When you look into that region of the sky and you tell astronomers that this is the place," Sokolsky said, "they shrug and they say, 'Well, there's nothing in particular there.'"

That's why they're spending a lot of money, hoping to answer the key questions: Where is the unknown energy source and what is it? The research involves about 130 scientists from about two dozen universities around the world, including the U. The price tag over the life of the project is well over $50 million, the bulk of the money coming from the governments of Japan and the United States.

Even if they solve the riddle, there is no guarantee the answer will improve our daily lives or have any practical value of any kind.

"Until you discover something, you don't know where it leads," Sokolsky said.

Lundquist agreed. "I mean, you know, when electricity was discovered," he said, "it was a novelty, a toy, a magic trick. And now it runs our lives."

Echoing the thought about electricity, Sokolsky said, "It completely revolutionized the world. But if you asked (James) Maxwell — one of the discoverers of electricity — what electricity was good for, at the time, he couldn't tell you."

Even without a practical justification, the pursuit of scientific knowledge is the driving force for many of the researchers. The "Oh My (Gosh)!" particle is an amazing curiosity that begs for an answer.

"Something in nature knows how to generate these energies," Sokolosky said, "and we'd like to find out what that is."

"Essentially what we're trying to do is, we're learning how the universe works," Cady said. "In the long run, knowing more about how the universe works has always turned out to be a useful thing."