Searching for clues to the universe
Scientists look to identify dark matter north of Cortez
DOVE CREEK — Southwest Colorado has always been a good place to find valuable things buried in the ground.
There are 1,000-year-old artifacts from a vanished culture, as well as uranium, natural gas and gold.
And now, some of the world’s most advanced scientists are going deep underground to look for clues to the nature of the universe itself.
Since 2010, scientists have been extracting a rare form of argon gas from a cluster of carbon dioxide wells on an escarpment north of Cortez. An international project called Darkside-50 plans to use the gas for an experiment that aims to identify “dark matter” for the first time.
At first glance, Darkside-50 sounds like a villainous plot from a science fiction movie, with government labs and elite colleges like Princeton University carrying out an experiment inside a hollowed-out Italian mountain with the aim of finding a mysterious substance called dark matter.
But really, it’s about answering an old question in astrophysics. Scientists have observed for decades that galaxies spin faster than they should based on the gravity of all the stars that are visible, said Henning Back, an engineering physicist at Fermi National Accelerator Laboratory.
“It sounds spooky, but really it’s because we know all this matter is there, and it’s emitting light, and we know there has to be something else, so we just called it dark matter, because it’s not emitting light,” Back said.
The right equipment
Planet Earth is flying through dark matter all the time, but no one has ever seen it. Back and his team think that with the right equipment, they should be able to sense it. That’s where Southwest Colorado’s argon gas comes in.
Argon and a few other gases are “scintillators” — they light up when radiation hits them.
The Darkside-50 team aims to extract 50 kilograms of argon, or about 110 pounds. The team will super-cool the argon until it becomes liquid — about 10 gallons’ worth.
Then, scientists will put the argon tank inside a 30-foot water tank inside Italy’s Gran Stasso underground laboratory. There, shielded from the sun and any other source of light, the Darkside team hopes to detect faint pulses of light in the argon whenever a dark matter particle hits it.
“We are not creating dark matter. We are literally just waiting for it,” Back said. “We’re going to hope to see something. But it could be that it interacts so little that we need an even bigger detector.”
In that case, they will need to build a one-ton-sized machine.
Argon is very common. In fact, almost 1 percent of the air we breathe is argon. But when argon is in the air, the sunlight hits it and it becomes very slightly radioactive.
“The fact is that everything’s radioactive,” Back said. “By weight, a banana is 100 times more radioactive than argon in the atmosphere.”
But that tiny sliver of radiation is enough to spoil the Darkside experiment.
So scientists started searching for underground deposits of argon that are shielded from the sun, and they found just what they were looking for at Kinder-Morgan’s Doe Canyon wells.
“I thought it was very interesting, but kind of strange that our little field in Southwest Colorado would get this attention,” said Coy Bryant, Kinder Morgan’s production manager in Southwest Colorado.
Building a gas extractor
Back’s group built an argon gas extractor inside the Kinder Morgan compressor plant. It doesn’t get in the way of the carbon dioxide processing, Bryant said.
Bryant likes knowing that his carbon dioxide field is playing a small part in cutting-edge research that people around the world are watching.
“Not that we have a huge role in it, but it is pretty neat,” Bryant said.
Kinder Morgan has been a great host, Back said.
At the same time, no one has been publicizing the research project.
Michele Martz, an organic farmer from Cahone, said she “had a hunch” that something unusual was happening at Kinder Morgan’s compressor plant, and she discovered the Darkside-50 project through a Google search.
Martz, co-owner of SongHaven Farm, said she’s satisfied that the argon project isn’t a health risk, but it raises questions about property rights to substances that come up Southwest Colorado’s wells along with carbon dioxide or natural gas.
“I was curious that it had never been put on record at the county level,” Martz said.
Argon has some commercial uses, like welding equipment, but the market for ultra-low-radioactivity argon appears to have just one customer: the Darkside project.
Back said his team has collected about half the argon they need for Darkside-50.
“Fingers crossed, we get everything we need this year,” Back said.
If the team succeeds in finding dark matter, it will start to fill in massive gaps in the human race’s knowledge about the nature of the universe.
“We still don’t know what that dark matter particle is,” Back said. “All of the energy in the universe, only 4 percent of it is stuff you can see, and what we’re made of and everything you know and have ever known.”
Some 23 percent of the universe is estimated to be dark matter. And three quarters of it is something else called “dark energy.”
The Darkside-50 experiment is not looking for dark energy. That remains a mystery to be solved another day, or by another generation.