A research team at Fermilab is set to observe ghost particles traveling through 1,287 kilometers between detectors, aiming to uncover the mysteries of the universe.
Nearly seven years ago, construction crews began excavating 800,000 tons of earth from an old gold mine near the city of Lead in South Dakota. The result is an underground cavern that is 152.4 meters long and tall enough to accommodate a seven-story building. The project, known as DUNE (Deep Underground Neutrino Experiment), is estimated to cost at least $3 billion and is led by scientists at the U.S. Department of Energy’s Fermilab. Each cavern will contain 17,500 tons of liquid argon to help physicists at Fermilab detect neutrinos, also known as ghost particles, according to Business Insider.
One of the caverns housing the neutrino detectors in the DUNE project. (Photo: Matthew Kapust)
Neutrinos are subatomic particles that permeate our surroundings and can pass through matter undetected. “If you clench your fist, approximately 10 billion neutrinos from the Sun pass through your hand every second,” said physicist Mary Bishai, a spokesperson for the DUNE project.
Neutrinos are nicknamed ghost particles because they are electrically neutral and therefore rarely interact with anything they encounter, making them extremely challenging to study. However, scientists persist because neutrinos may play a crucial role in unraveling many cosmic mysteries, from what happened after the Big Bang to observing the formation of black holes. Investigating a particle that does not emit radiation and is lighter than an electron poses a significant challenge, according to Bishai.
The expert team at Fermilab aims to study neutrinos in unprecedented detail with DUNE. This is why DUNE will feature the largest neutrino detectors ever built. Once completed, the experiment will commence with a series of particle accelerators at Fermilab’s facility outside Chicago, Illinois. These accelerators will fire a powerful beam of neutrinos through the detectors at Fermilab. The particle beam will then travel underground for 1,287 kilometers to a detector at the Sanford Underground Research Facility in South Dakota.
There are three types of neutrinos, and particles can transform between these types in a phenomenon known as oscillation. A scientist at Fermilab once likened this phenomenon to a house cat transforming into a leopard, then into a tiger before returning to its original form. Tracking how neutrinos change over such a long distance between Illinois and South Dakota will help scientists gain a better understanding of oscillation. Conducting the experiment 1.6 kilometers underground protects the delicate oscillating particles from cosmic rays that continuously bombard the Earth’s surface every second, posing a risk to the data.
Scientists hope to answer three key questions with DUNE: Why is the universe composed of matter instead of antimatter, what happens when a star collapses, and do protons decay? The DUNE particle beam is designed to produce both neutrinos and antineutrinos. Observing oscillation in each type may help researchers predict what happens to all antimatter.
The project also contributes to supernova physics, according to Bishai. In 1987, astronomers witnessed the brightest supernova explosion in 400 years. With the detectors available at that time, they could only detect just over twenty neutrinos. There is a 40% chance that another nearby star may explode in the next decade, and Fermilab hopes that at least one of the detectors in South Dakota will be operational in time. Such a large detector could collect thousands of neutrinos, revealing how black holes and neutron stars are formed.
Ultimately, scientists have yet to observe proton decay, but there are theories predicting it. Protons are tiny positively charged particles found in an atom’s nucleus. If protons decay, the process would take an incredibly long time. However, the neutrino detectors may search for various signs of proton decay.
Currently, there are several neutrino projects around the world, including the Japan Proton Accelerator Research Complex (J-PARC) and the European Organization for Nuclear Research (CERN). What makes DUNE unique is its use of argon and the long distance between the detectors.
Due to budget and scheduling issues, the DUNE project is designed with four argon detectors but will initially operate with two. The first detector is expected to be operational by the end of 2028, with the second following a year later. They will function in the event of a supernova explosion, but the particle beam will not be ready until 2031. The project is a collaboration involving 1,400 individuals from 36 countries.
