Two recent articles in the Millard County Chronicle have dealt with the upcoming Telescope Array Expansion
Big Science
March 6, 2019
Mat Ward - Big science in Millard County is about to get much, much bigger. By a factor of four, to be exact.
The Telescope Array Project—the multinational cosmic ray observatory that calls Delta home—is undergoing an expansion with the placement of 260 new surface detectors over a wider area. New telescopes are planned for observation posts on Middle Drum and Black Rock Mesa as well.
The observatory has collected data for more than a decade on ultra high energy particles that enter the Earth’s atmosphere and collide with the nuclei of air molecules, creating showers of secondary particles that fall to the ground. Telescopes capture the high-speed flashes of light created by the collisions in
the sky, while the ground detectors absorb the secondary particles, sending notice back to computers at the Millard County Cosmic Ray Center that such a high-energy event has occurred.
Starting last month, scientists from the University of Utah and the University of Tokyo began monitoring the placement of about the new ground detectors, ping-pong table-sized devices called scintillators. The detectors are being placed by helicopter in the desert north and south of Delta. A couple of hundred more detectors will be added sometime later, effectively doubling the number
of detectors currently in operation.
The expansion, according to a Japanese newspaper article published in February, will cost about $4.5 million, most of that funding coming from Japan. The article said expansion work was slated to begin in January, but was stalled by the recent federal government shutdown.
Bob Cady, a retired University of Utah research faculty member, was assisting in the field work recently at a desolate patch of snow-covered desert north of Delta.
“We’re trying to quadruple the size. We’re doubling the number of counters, but we’re putting them farther apart. Hopefully we’ll cover four times the area. We’ll cover three times the area, plus the area
we have,” he said. “A factor of four.”
Once complete, the Telescope Array will cover an area of about 1,160 square
miles.
Cady was joined by researchers from Utah and Japan, including Professor Hiroyuki Sagawa of the University of Tokyo’s Institute for Cosmic Ray Research.
The ground detectors’ scintillators are built in Japan by the Akeno Observatory. Sagawa is the observatory’s director.
“Originally, in 1990, there was a ground array in Japan, with 100 square kilometers,” Sagawa explained. “It was one-seventh (the size) of the current one. The current one is three times larger than Salt Lake City.”
With 760 detectors, new telescopes and an area four times its current size, scientists are hoping to capture better data on the mysterious high energy cosmic rays, some of which enter the atmosphere with such ferocity that their mere existence represents the tantalizing possibility of a paradigm shift in our understanding of the universe—high energy cosmic rays might stem from material jetted from black holes at the center of galaxies, or are super fast remnants of supernovas. The high energy particles are more energetic than any produced by the world’s largest particle accelerators.
About 130 researchers from 34 universities and research agencies throughout the world, including in Belgium, Russia, South Korea, the Czech Republic and 10 schools in Japan, examine the cosmic ray data collected in Delta.
Marriage of experiments
The Telescope Array grew out of a wedding between the Japanese-based ground array from the 1990s and an earlier version of the University of Utah’s fluorescence telescope system called the Fly’s Eye, which operated from 1981 to 1993 at the U.S. Army’s Dugway Proving Ground. A higher resolution version of the Fly’s Eye called HiRes operated from 1997 to 2006.
A scientific dilemma existed, however, between what the Japanese were witnessing with their ground array and what Utah scientists were detecting with their fluorescence technique.
“A long time ago, the Japanese group, running a big ground array in Japan, they came up with one answer for the highest energies (detected among cosmic rays),” Cady said. “And the University of Utah was running their telescopes here in Utah. And we would come up with a different answer. The only way to decide who was right, or even if both of them were wrong, was to use both techniques at the same place. The fluorescence technique does not work very well in Japan. The air is too humid. You have to be in a place with dry air. So they had to come here.”
The desert in Millard County offers the perfect elevation at 4,000 feet above sea level as well as the dryness needed for optimal performance of the ground scintillators.
Sagawa further explained the early discrepancies between the Utah and Japan results.
“The Japanese result was no cutoff, at the highest energy end. But the Utah result was an energy cutoff at the highest end. We want to solve the discrepancy. For that we need larger detectors,” he said.
Still, the cosmic ray detection taking place is constantly evolving.
A radar-based approach
Because of the high cost and work involved in ground based and telescopic cosmic ray detection, a new approach was experimented with over the last few years. It was hoped that it may someday replace the costly method now in place to study cosmic rays.
TARA, or Telescope Array Radar, used a modified television transmitter to create radio waves that are scattered by the energy showers produced by cosmic ray impacts in the upper atmosphere. The theory was that using radar to detect cosmic rays offers a cheaper way to cover a much larger piece of real estate in order to record the rare events. Clear, dry, moonless nights are required to effectively capture cosmic rays with telescopes. But radar seemed to offer the opportunity to eliminate such environmental obstacles.
The use of radar to detect cosmic rays was first proposed in 1941, according to a 2017 academic paper about the experiment, after scientists recorded anomalous atmospheric radar echoes presumed to be caused by some sort of cosmic ray-induced particle showers.
Low radio interference in Millard County made the Telescope Array an ideal place to study the accuracy of radar detection in conjunction with the ground-based and telescopic detection techniques.
Sagawa said, unfortunately, the results of radar detection were limited and the TARA experiment eventually scrapped.
New detectors placed in West Desert
March 1, 2017
Dana Jordan - The Cosmic Ray Center in Delta is expanding its area of research. The center deployed about seventy new detectors by helicopter to their permanent locations, south of the telescope observatory, near the Drum Mountains, on Feb. 22 and 23.
The detectors, about the size of ping-pong tables, are sprinkled across the desert west of Delta. They measure the remnants of cosmic ray showers as they hit the Earth’s surface.
John Matthews, research professor and project manager of the Cosmic Ray Research Group, explained that unlike the low-energy particles from the sun, there are extremely high energy particles coming from space, which spill out light as well as charged particles.
“It is more energy than a super nova, and is 100 million times more energetic than those we can generate in the collider in Geneva,” explained Matthews, “It could be something like two black holes swirling around each other, and emitting particles that don’t get sucked in. We’re trying to figure out exactly what it is, where they are coming from and how to make them.”
Matthews explained that these cosmic rays are very rare, only emitting one per square kilometer per century or less, which is why they need a lot of area for their research.
“Millard County has a lot of flat space and it’s dark out there. There’s not a lot of light pollution or dust in the air,” he said, “We use lasers to measure how dirty the air is, and adjust calculations according to those levels. The air around Delta is pretty clean most of the time.”
According to Matthews, a charged particle comes from space, hits the earth’s atmosphere, and breaks the nuclei of oxygen or nitrogen molecules in Earth’s atmosphere. The secondary particles hit other molecules, creating a shower of millions of secondary particles, some of which hit the earth’s surface.
The detectors deployed in the desert record the footprints of that shower, which spreads out over a 300-mile radius. The current detectors will be placed closer together than the ones in the past; about 400 yards apart, rather than three quarters of a mile apart.
Detectors are placed near one of the three telescope observatories, which on clear nights detect the glowing, ultraviolet view of the charged particles. The telescopes are very fast and sensitive and can see the showers come down through the atmosphere, but they don’t work during the day, when the moon is too bright, or when the sky is cloudy.
The detectors are enclosed in dark boxes, so they can see 24/7, and work even when it’s sunny, cloudy or windy. When the two work together it is easier to determine the direction and chemical composition of the particles.
The research center has been able to collect about 100 cosmic rays since beginning of operations in 2008. They hope to increase the area of research over the next few years by placing many more detectors. They are looking at areas northwest of IPSC and others south of Delta by Pahvant Butte.
The cosmic ray project is funded in the United States by the National Science Foundation. Two thirds of the funding for this project comes from the science foundation of Japan, where the University of Tokyo works in close contact with the University of Utah. These two universities lead the world in cosmic ray research since the 1950s. They decided to combine research efforts and data in the late 1990s.
“It is considered basic research, with no immediate application of the data,” said Matthews, “It is purely a research project to understand the universe better.”
“One of the most important things we have learned is these high energy rays are colliding with the leftover noise of the Big-Bang, and they create new particles, but lose their energy,” he said, “We’re starting to see signs that we may have discovered the first source of these very high energy cosmic rays. We’re seeing a bright spot in the sky that’s just a little bit south of the Big Dipper and we’re trying to figure out what it is. We need more data to see if it is a source.”
The original articles can be found here:
