Tag Archives: dune

Tests for the largest neutrino experiment yet begin with the DUNE Buggy

The Deep Underground Neutrino Experiment Collaboration has started the first batch of tests using a small-scale 35 tons prototype of the final device, dubbed the DUNE Buggy. The team is busy gathering readings from the prototype to tweak and optimize the design of the final device.

Inside the 35-ton prototype.
Image credits Reidar Hahn

So….Why does the Universe (and all the matter in it) as we know it exist?

If you don’t know the answer, don’t worry, nobody does. But we want to know, so an international collaboration has brought together some of the best and brightest minds today to find these answers using the DUNE – the Deep Underground Neutrino Experiment. It will be used to find out whether neutrinos are their own antiparticles, and reason our predominantly-matter-filled universe exists; it will watch for the formation of a black hole in a nearby galaxy; and, by searching for signs of proton decay, it will bring us closer to realizing Einstein’s dream of a unified theory of matter and energy.

“Of the Standard Model particles, neutrinos are some of the least well understood,” says Célio Moura, a professor at the Federal University of ABC in Brazil who works on the prototype.

“We need huge experiments to get this difficult information about neutrinos. But we have to start little by little.”

The final stage of the DUNE will require a staggering 70,000 tons of liquid argon, making it the largest experiment of its kind–100 times larger than the liquid-argon particle detectors that came before it. The DUNE will be built a mile underground, at the Sanford Underground Research Facility, where it will be shielded from most outside radiation. But, due to the immense scope of the project the team understandably want to make sure that the detector is actually going to work as intended, so the project started with a small-scale test version of the device.

“How can we be confident that what we want to do for DUNE is going to work?” says Michelle Stancari, co-coordinator of the DUNE prototype.

“That’s where the 35-ton comes in.”

One of those little steps Professor Moura talks about is, ironically, anything but small — the construction of one of the largest liquid-argon time projection chamber ever. Built by the Department of Energy’s Fermi National Accelerator Laboratory, this prototype came to be known as the “DUNE buggy” after an artist working on the project Photoshopped monster truck wheels on an image of it.

The chamber is used to detect cosmic rays that, when passing through the liquid argon, emit electrons and light. This visible response can be measured, the location and intensity of each burst being collected and digitized. With this data, the team can recreate the particles’ direction and speed of travel, momentum, energy, and type. The prototype will allow them to check that various detector components work as they should, followed by preliminary experiments.

“The goal of this is to find out where the weak points are that need to be fixed, and also hopefully figure out the parts that work,” says Fermilab’s Alan Hahn, co-coordinator for the 35-ton.

Some of the components haven’t ever been tested before. Among these are redesigned photodetectors, long rectangular prisms with a special coating that change invisible light to a visible wavelength and bounce collected light to the detector’s electronic components. DUNE scientists are also testing the prototype’s wire planes, which hold the thin wires strung across the detector to pick up electrons. These should measure tracks in the liquid argon both in front of and behind them, unlike other detectors.

“No one else has that,” Hahn adds. “One of the main goals of the 35-ton run is to show that we can reconstruct tracks from such a wire plane.”

The wire planes inside the 35-ton prototype.
Photo credits Reidar Hahn

Engineers have also moved some of the detector’s electronic components inside the cryostat, which holds liquid argon at minus 300 degrees Fahrenheit (-184 degrees Celsius).

The DUNE collaboration has about 800 members from 26 countries around the world. For the prototype, Brookhaven and SLAC national laboratories provided the bulk of electronic equipment; Indiana State University, Colorado State University, Louisiana State University and Massachusetts Institute of Technology developed the light detectors; Oxford, Sussex, and Sheffield Universities made the digital cameras that can survive in liquid argon and compiled the software to make sense of the data. Fermilab was responsible for the cryostat and cryogenic support systems.

“It has to be really international—otherwise it wouldn’t work,” says Karl Warburton, PhD student at the University of Sheffield in the UK who works on the prototype.

“You need the best minds from everywhere. It’s the same as with the LHC.”

The next step is using the data mined from this prototype to build full-scale modules for a much larger 400-ton prototype at CERN.

“It’s been very important for the collaboration to have this prototype as a milestone,” says Mark Thomson, co-spokesperson for the DUNE collaboration and professor at the University of Cambridge.

“It’s an absolutely essential step.”

After that, the team will begin working on the first of four detectors for the actual experiment, scheduled to start in 2024.

titan saturn dune

Saturn’s Moon Titan has Strong Winds and Hydrocarbon Dunes

New experimental research found that Saturn’s largest Moon, Titan, has much stronger winds than previously believed. These rogue winds actually shape the hydrocarbon dunes observed on its surface.

titan saturn dune

Cassini radar sees sand dunes on Saturn’s giant moon Titan (upper photo) that are sculpted like Namibian sand dunes on Earth (lower photo). The bright features in the upper radar photo are not clouds but topographic features among the dunes.
Credit: NASA

Titan is, along with Earth, one of the few places in the solar system known to have fields of wind-blown dunes on its surface. The only other ones are Mars and Venus. Now, researchers led by Devon Burr, an associate professor in Earth and Planetary Sciences Department at the University of Tennessee, Knoxvillehas haves hown that previous estimates regarding the strength of these winds are about 40% too low. In other words, Titan has much stronger winds than previously believed.

Titan is the only known moon with a significant atmosphere, and just like Earth’s atmosphere, it is rich in nitrogen. The geological surface of the moon is also very interesting, with active geological processes shaping it. The Cassini spacecraft captured spectacular images of seas on Titan, but before you get your hopes up, you should know that the seas are not made of water, but of liquid hydrocarbons. However, many astronomers believe that Titan actually harbors an ocean of liquid water, but below its frozen surface – the surface temperature is –290° F (–180° C). It’s actually so cold, that even the sand on Titan is not like the sand on Earth – the sand is also made from solid hydrocarbons. But the thing is, we don’t really know where those grains come from.

“It was surprising that Titan had particles the size of grains of sand — we still don’t understand their source — and that it had winds strong enough to move them,” said Burr. “Before seeing the images, we thought the winds were likely too light to accomplish this movement.”

But the biggest mystery was the shape of the dunes. The Cassini data showed that the predominant winds that shaped the dunes blew from east to west. However, the streamlined appearance of the dunes around obstacles like mountains and craters  suggested that the winds blow from the opposite direction.

In order to figure this out, Burr and his team spent six years refurbishing a defunct NASA high-pressure wind tunnel to recreate Titan’s surface conditions. After the restauration was complete, they used 23 different varieties of sand in the wind tunnel to compensate for the fact that we don’t know exactly what the sand on Titan is made from. The first thing they found is that for all the likely varieties of sand, the winds have to be much stronger than believed.

“Our models started with previous wind speed models but we had to keep tweaking them to match the wind tunnel data,” said Burr. “We discovered that movement of sand on Titan’s surface needed a wind speed that was higher than what previous models suggested.”

They also found an explanation for the shape of the dunes.

“If the predominant winds are light and blow east to west, then they are not strong enough to move sand,” said Burr. “But a rare event may cause the winds to reverse momentarily and strengthen.”

According to the models, this wind reversal takes place every Saturn year – which is 30 Earth years. This also explains why Cassini missed this reversal.

“The high wind speed might have gone undetected by Cassini because it happens so infrequently.”

Journal Reference:

  1. Devon M. Burr, Nathan T. Bridges, John R. Marshall, James K. Smith, Bruce R. White, Joshua P. Emery. Higher-than-predicted saltation threshold wind speeds on Titan. Nature, 2014; DOI: 10.1038/nature14088