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Eugene Loh spent much of his University of Utah career trying to detect cosmic rays - powerful particles too small to be seen by the human eye - that constantly bombard the Earth's atmosphere.

The pioneering work of the professor emeritus of physics helped provide new ways to scan the night skies for the presence of high-energy particles hurtled toward the planet from somewhere in the universe.

Loh died Friday of kidney cancer at his home in Arlington, Va., at 72.

He came to the U. in 1975 and worked with a team to create a prototype cosmic ray detector that was tested in the New Mexico desert.

The results were promising enough that the U. secured $3 million to build a network of detectors at the U.S. Army's Dugway Proving Ground. The array, known as the Fly's Eye, peered skyward from the late 1970s through the mid-1990s.

Before the Fly's Eye, scientists had tried to detect cosmic rays by looking for debris left by the particles. Loh and others found a way to indirectly detect the high-energy particles ripping through the atmosphere, said Pierre Sokolsky, chairman of the U.'s physics department.

When a high-energy particle enters the atmosphere, it bumps into particles, which in turn bump into other particles to create a cascade effect. Each of these collisions emits a burst of ultraviolet light, not visible by the eye, but detectable using sensitive equipment. A series of specially-designed mirrors at Dugway watched the cascade of lights fall through the sky to learn about the cosmic rays.

In 1991, the Fly's Eye array recorded the most energetic cosmic ray ever detected.

"What we have is a particle that hasn't been detected before," Loh told The Salt Lake Tribune when the find was announced in 1993. "We love to see things we have never seen before."

The U. replaced the original Fly's Eye with the High Resolution Fly's Eye, which began sky-watching duties in 1999. As the name implies, the new system scans the skies at a higher resolution offering greater detail.

Among the memories of Loh that stand out for Sokolsky were the times they worked in the trailer at Dugway that recorded data from the Fly's Eye.

"If there was something wrong, he would zero in on it instinctively," he said of Loh's electronic repair skills.

Sokolsky also recalled being impressed with one of Loh's less-scientific skills - one look from the physicist would make babies smile.

"Anyone who could fix electronics, and whom babies loved, can't be all bad," Sokolsky said.

Despite a soft-side for toddlers, Loh could be tenacious when it came to pursuing his scientific goals and the needs of his field. Even when administrators turned down his plans, he would remain undeterred and come back keep fighting. In the late 1990s, Loh moved to Virginia where he continued pushing to find more money for his colleagues while working for the National Science Foundation.

"You couldn't keep him down," Sokolsky said.