To understand the world above the ground, sometimes it helps to go deep under ground, where scientists can shield experiments from light, cosmic rays and other interference. That's why U.S. researchers are proposing an entire mountain in Colorado for what could become the world's largest deep underground laboratory. It may open new frontiers in every-thing from biology to astrophysics.
Granite mountain holds potentialOne hour west of Denver, holiday travelers and truckers hauling freight speed through the Colorado Rockies, intent on skiing down the mountains or getting over them. But inside one mountain is a hive of activity. Miners drive bulldozers and trucks, removing a steady stream of molybdenum, which is used to strengthen steel.
This is Henderson Mine's Red Mountain, named for its reddish color, a common shade for ore rock. The miners blast out the molybdenum then dump it on a crusher that smashes 80 tons in a single gulp. Henderson's owners see profit in the power of modern mining equipment. Scientists see a research opportunity, as they think about what that machinery could do in the gray mountain Henderson Mine owns next to Red Mountain.
It's called Harrison Mountain. Bob Wilson, a particle physicist at nearby Colorado State University, describes it as "dull granite. Doesn't have the tinge, doesn't have mineral ore. Nothing commercially interesting there." But scientifically, there's plenty about this bit of earth to attract attention.
Wilson, who knows the importance of doing research in a quiet, shielded environment, believes that Harrison Mountain could be the perfect location for a lab, with the help of Henderson Mine's equipment. "We want a place where we can dig big cavities that aren't going to fall down on us," he explains. "We want big, dull boring granite. And we can do it because all of their infrastructure for excavating, doing the mining, is right there."
Lab would serve scientists in many fieldsIf approved, Harrison Mountain would become America's first official Deep Underground Scientific and Engineering Laboratory. The lab would help geologists study how dull, boring granite changes into valuable ore rock. And other scientific fields would also benefit.
University of Colorado biologist Jeff Mitton says that being deep underground will reveal hidden realms of life. He displays a core sample from Harrison Mountain, noting that his team found living organisms in it. "So there are microbes living [1830 meters] below the surface in what you or I would identify as dry solid rock. It may be that that's a natural museum for some of the very earliest forms of life. It's a possibility, and it's tantalizing," he concludes.Just as tantalizing is the opportunity for physicists to study whether protons decay and what neutrinos are all about. But it's hard to catch these subatomic particles in action, especially since they can pass straight through the earth without colliding with anything. A neutrino is so hard to figure out, its nickname is 'the ghost particle.'
Huge underground caverns needed to study sub-atomic particles
University of Colorado physicist Eric Zimmerman says a tiny neutrino can be both matter and antimatter, simultaneously, adding "It is possible that the neutrino is actually its own anti-particle." When matter collides with its antimatter counterpart, they erase each other. But among neutrinos, there might be a little more matter than antimatter. Zimmerman says this makes these particles one of the hottest topics in physics. "We want to understand how the universe works and why the world is made of matter."
Nobel Prizes have been awarded for neutrino research, with more likely to follow. But as for practical applications, those are still in the distant future. Bob Wilson counsels patience. He points out that when the electron was discovered a century ago, scientists had no idea what they could do with it. Now, he notes, "The electron is the basis of all technology. The electrical current is just electrons moving around. Semiconductors are essentially manipulating the electron and understanding atomic properties." He says that understanding neutrinos may give us a better understanding of fundamental forces that govern nuclear power operations and cause the sun to burn and stars to explode.
Being deep underground makes neutrino research easier, because all those meters of granite screen out cosmic rays. It's also easier to spot neutrino interactions when zillions of particles can be monitored at once. Eric Zimmerman says one of the best ways to watch them is in a sort of water bucket; a very large bucket, like an underground cavern filled with water. "It's one of the ironies in science," he says with a shrug. "The smaller the object you want to look at, the bigger the equipment you need to look at it. So we're talking about a cavity that's over a mile under the surface of a mountain that's the size of a modern basketball arena."
And then, Bob Wilson says, the ghostly particles may leave a trace. "Most of them will stream right through the mountain," he acknowledges, "will pass right through the detector, and not even wave as they go by. But that one in a billion, that interacts in the detector, we see it, and we'll say, 'aha!'"
Thanks to sturdy granite and high-tech digging equipment, the Henderson Mine is a finalist for the first U.S. Deep Underground Laboratory. The National Science Foundation will make a decision this spring, then earmark $300 million to create a world-class space for studying rocks, life and neutrinos.