September 2019    
  Scientific gold mine  
  The Deep Underground Neutrino Experiment will search for ghost particles.  
  Inside a prototype detector module for the international DUNE experiment, built at CERN. The golden glow of its stainless steel surfaces is an optical illusion. To protect the photo detection system, techs use yellow light. (Photography by Maximilien Brice, CERN)  
  A former gold mine in the Black Hills of South Dakota now houses the Sanford Underground Research Facility, where an enormous neutrino detector will be installed in 2022 for the Deep Underground Neutrino Experiment (DUNE). A smaller detector will go online by 2026 at Fermi National Accelerator Laboratory, which hosts the project.  
  DUNE and its team of 1,000 scientists from more than 30 countries will study mysterious "ghost particles" called neutrinos. These elusive elementary particles could reveal the origin of matter, shed light on the unification of forces, and explain the nature of neutron stars and black holes.  
  While they're the most abundant type of matter, neutrinos have no charge, have almost no mass, and barely interact with other particles--making them notoriously difficult to catch.  
  Neutrinos also oscillate, or transform as they travel. Imagine buying a carton of chocolate ice cream at the store and then finding it's vanilla when you get home. Then when you taste it, it's strawberry. The different neutrino forms are in fact called flavors, and their oscillations could explain why anything exists (or more precisely, why there's more matter than antimatter in the universe).  
  To study neutrino behavior, Fermilab will use its powerful particle accelerators to shoot the world's most intense beam of neutrinos through 800 miles of earth, from Illinois to South Dakota, where the world's largest liquid argon detector will record neutrino interactions with argon atoms. Since the accelerator will beam trillions of neutrinos into 70,000 tons of argon, the detector should catch a handful of collisions every day.  
  Fermilab explains the science of the Deep Underground Neutrino Experiment (DUNE).  
  DUNE is a massive undertaking, so the team first built ProtoDUNE-SP: a prototype 1 percent of the final detector's size (and already the largest argon detector ever built). ProtoDUNE's researchers collected more than 4 million images of particle interactions, exceeding their simulations-based expectations.  
  Fermilab broke ground in March on the particle accelerator that will power DUNE. In the meantime, the team has plenty to do with ProtoDUNE--starting up a second prototype detector, conducting more hardware and software tests, and seeing how the prototype ages, as DUNE will collect data on neutrinos for decades to come.  
  Get to know neutrinos  
Fermilab offers a primer in "all things neutrino." Learn about Sesame Street neutrinos, southpaw particles, and impossible mirror images.
Bananas have a tiny amount of radioactive potassium, making them a neutritious fruit.
UChicago physicist Juan Collar helped build the world's smallest neutrino detector.
Adam Nadel, AB'90, Fermilab's 2018 artist-in-residence, took the raw data from a neutrino interaction and transformed it into music.
  Hot on the trail  
  Neutrino tracks inside a bubble chamber, a type of detector invented in 1952, were captured on film. (Image courtesy Argonne National Laboratory)  
  A neutrino interaction was observed with a hydrogen bubble chamber for the first time in 1970 at Argonne.  
  A precursor to the liquid argon detector, a bubble chamber is a tank filled with pressurized, superheated transparent liquid, often hydrogen or a hydrogen-neon mix.  
  Just before an accelerator beam enters the chamber, the pressure is reduced. The charged particles then boil the liquid, forming bubbles along their paths, which curve in a magnetic field, allowing researchers to study particle momentum.  
  In case you missed it  
Water worlds: Planetary scientist looks beyond Earth's example for life.
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