WorldWide Drilling Resource

32 JUNE 2022 WorldWide Drilling Resource® Drilling for One of Nature’s Tiniest Particles Adapted from Information by Fermilab A flurry of activity is happening nearly a mile underground in South Dakota. Three shifts of 30 construction workers labor around the clock, carving out subterranean space for science in a huge effort centered around one of the tiniest things in nature, the neutrino. Neutrinos are fascinating particles. Trillions of them pass through you every second without a trace. They are produced by almost everything, including Earth, the sun, supernovae, bananas, and people. These bizarre building blocks could hold the key to understanding why matter exists in the universe, rather than antimatter, or nothing at all. To better study these elusive particles, an international collaboration of more than 1000 scientists are building the Deep Underground Neutrino Experiment (DUNE) hosted by the U.S. Department of Energy’s Fermi National Accelerator Laboratory (Fermilab). Researchers will study a beam of neutrinos as it leaves Fermilab in Illinois and again when it reaches the Sanford Underground Research Facility in South Dakota. The particles will travel 800 miles straight through the earth to go from lab to lab with no tunnel needed. The DUNE detector in South Dakota will be the largest neutrino detector of its kind ever made. Each of the four detector modules will hold 17,000 tons of liquid argon, in which neutrinos will interact and leave their signature traces. Creating the Long-Baseline Neutrino Facility involves making space for massive instruments and their support equipment. It will require moving roughly 800,000 tons of rock, creating caverns big enough to hold the bodies of four jumbo jets. Before large-cavern excavation can begin, prep work must be completed. The first step is widening existing underground tunnels, called drifts, and creating a ¼-mile-long vertical ventilation shaft. The opening will improve the flow of air needed for excavation a mile underground where the main construction work will take place. Raise-bore drilling will be used to create the ventilation shaft. First, construction workers drilled a 1200-foot-long pilot hole about a foot in diameter from the 3650-foot level down to the 4850-foot level. The drill bit used sensors called inclinometers to detect any deviation from vertical, sending real-time data to a computer that issued corrections to the steering mechanism. The pilot hole was completed with the drill emerging mere inches from its target in the cavern. With the pilot hole complete, workers at the 4850-foot level replaced the drill bit with a large reamer. The circular tool is about 12 feet wide and spins as the construction crew pulls it up through the ceiling, chewing out rock as it goes. The debris falls down to the 4850-foot level, where it is scooped up, transported to the Ross Shaft, and taken for a mile-long ride to the surface. A conveyor system then brings the rock another ¾-mile to a former open-pit mining site called the Open Cut. The raise-bore technique “is probably the best method to build circular shafts,” said James Rickard, the Fermilab resident engineer managing the excavation. “And it’s very good for hard rock,” the type present at the facility. Along with excavation of the main caverns, crews will also enlarge some of the drifts and the area around the Ross Shaft to create more space for transporting DUNE equipment. For this excavation, as well as eventual excavation of the main caverns, teams will switch to the drill and blast technique, using explosive charges placed in small holes. When the space is ready, researchers will begin bringing in components needed for the massive experiment underground and assembling the detector, like a ship in a bottle. DUNE will address three major science goals: determine why matter exists in the universe; watch for neutrinos from a supernova in our galaxy; and look for unexpected subatomic processes, such as proton decay, a phenomenon which has never been observed before. The drill head broke through the roof at the 4850-foot level to complete the pilot hole for the raise-bore ventilation. EXB