2021-12-17

NASA has approved the pueo experiment in Antarctica to find highly energetic “ghost” particles in the universe

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c0b17118fc76a62 - NASA has approved the pueo experiment in Antarctica to find highly energetic "ghost" particles in the universe

“we are looking for the most energetic neutrino in the universe,” said vieregg, an associate professor of physics at the University of Chicago. “They are produced in the most energetic and extreme places in the universe, and these neutrinos provide a unique peek into these places. Finding one or several of them can let us know something new about the universe.”

this international cooperation project composed of 12 institutions will establish a radio detector attached to a high-altitude balloon, which will be launched by NASA and fly 120000 feet over Antarctica to search for signals from neutrinos. This groundbreaking project is called pueo, short for the payload of ultra-high energy observation. (its name is the same as the only existing owl in Hawaii, and the predecessor experiment of pueo was born here).

30c60158b59b344 - NASA has approved the pueo experiment in Antarctica to find highly energetic "ghost" particles in the universe

a beautiful way to observe the universe

neutrinos are often called “ghost” particles because they rarely interact with matter. Tens of thousands of neutrinos pass through your body harmlessly every second. Because they can travel huge distances without being distorted or deviated, neutrinos can serve as unique clues to what happens elsewhere in the universe – including cosmic collisions, galaxies and black holes they produce

vieregg said: “neutrinos are a beautiful way to observe the universe because they travel unimpeded through space. They can come from very distant places, and they will not be disturbed on the way, so they will point to their source.”

scientists have detected some such neutrinos from outer space entering the earth’s atmosphere. But they believe that there are more neutrinos outside. They have extremely high energy – even several orders of magnitude higher than the particles being accelerated by the European Large Hadron Collider – and have never been detected. These neutrinos can tell us about the most extreme events in the universe

these neutrinos rarely interact with other forms of matter, so vieregg had to build a huge detector to capture them. Or she could use an existing probe: the ice sheet at the top of Antarctica

vieregg said: “the ice sheet is perfect – a homogeneous, dense, radiative and transparent mass, spanning millions of square kilometers. It’s almost like what we designed.”

if one of these high-energy neutrinos passes through the earth, it may hit an atom in the Antarctic ice. This collision produces radio waves that pass through the ice. This radio signal is what pueo will detect when it floats over Antarctica

to do this, it requires some very, very special equipment

NASA has approved the pueo experiment in Antarctica to find highly energetic “ghost” particles in the universe

pueo is the next generation of a mission called Anita, which is based on the University of Hawaii. From 2006 to 2016, it used NASA balloons to fly over the south pole four times to find similar neutrinos. However, pueo will have a more powerful detector

the new detector uses the power of an ancient astronomical technique — a technique called interferometry, which combines signals from multiple telescopes. Pueo is full of radio antennas, and a central data acquisition system will combine and analyze these signals to form a more powerful signal

a stronger signal will be a major leap, because it will help scientists select important signals from noise from all directions. “Thousands of megabytes of data enter the detector every minute. We expect that at most a few of the billions of events are neutrinos,” said cosmon deaconu, a research scientist at the University of Chicago, who is studying pueo software. “You can’t write all the data to disk, so we must design a program to quickly decide which signals to keep and which to discard.”

many common signals look like neutrinos, but they are not. These signals range from satellite transmission to someone’s lighter. “At least in Antarctica, there are only a few places where humans generate these signals, so it’s easier to exclude these signals. But we even need to consider factors such as static electricity,” deaconu said

vieregg and his team tested the idea of ground interferometric phased array in two experiments: ara in Antarctica in 2018 and rno-g in Greenland in the summer of 2021. Both experiments show a great leap in performance over the previous design – which makes pueo’s air detector more promising. “Pueo will be 10 times more sensitive than all previous flights of Anita combined,” vieregg said

in the next few months, the team will prototype and finalize the design for pueo. Once the layout is completed, small teams from institutions across the United States will build part of the instrument, which will then be assembled and tested at the University of Chicago. “For example, we want to make sure it can handle the vacuum in near space,” said Eric oberla, a research scientist at the University of Chicago, who is building the hardware of pueo. “When there is no air to take it away, it is more difficult to dissipate heat, which is a problem for electronic products, so we will test it in a vacuum chamber on campus, and then in a large vacuum chamber of NASA during the instrument integration activity.”

from there, pueo will be transported to NASA facilities in Palestine, Texas for final testing, and then sent to the launch station in Antarctica

depending on the weather conditions, the detector may fly for a month or more to collect data and transmit it back to the ground. Scientists will comb these data there to find evidence of the first high-energy neutrino detection in history

“we are glad that pueo stratospheric balloon mission was included in the initial group of the pioneer mission and look forward to the great science it will return,” said Michael Garcia, head of NASA’s astrophysics pioneer program, which funded the experiment

the pioneer program allows scientists to “have great dreams”, vieregg said. “We can say,’if we can make anything we want, what can we make?’

” this is a discovery experiment, which means that nothing can be guaranteed, “she added: “But all the signs show that there is something we can find there – even some neutrinos can be an amazing scientific discovery.”