LBNF/DUNE science goals

Neutrinos may hold the key to solving the great mysteries of nature: What is the origin of matter? What is the relationship between nature's forces? And how do the most extreme objects of our galaxies form? Why do we exist?

Neutrinos are everywhere yet fleeting. Trillions pass through us every second without leaving a trace. In nature, they are produced in great quantities by the sun and other stars. Scientists can also create neutrinos in the laboratory with huge particle accelerators, and these neutrinos can be tracked with extremely sensitive detectors. Scientists must generate enormous quantities of neutrinos to study them in the detail needed to understand how our universe works.

Before 1998, scientists believed that neutrinos were massless. That was what was predicted by the Standard Model — the mathematical framework that describes the subatomic realm. Then, in 1998, scientists discovered that neutrinos did possess a tiny bit of mass after all. The discovery overturned decades of assumptions on neutrinos and raised further questions about the universe. It was evidence that the universe included physics that the Standard Model didn't account for. And it turned the study of neutrinos into an important, global field of scientific study.

DUNE has three primary science goals:

1. Search for the origin of matter

DUNE scientists will look at the differences in behavior between neutrinos and antineutrinos, aiming to find out whether neutrinos are the reason the universe is made of matter.

origin of matter

We exist because matter won out over antimatter 13.8 billion years ago.

Evidence suggests that a smidge more matter than antimatter developed in the first millionth of a second after the Big Bang. Matter and antimatter annihilate each other, so that extra smidge survived. Instead of the nothingness that would have been the result of a perfect matter-antimatter balance, we have a universe that is full of galaxies, planets and, on at least one planet, people.

Neutrinos could enlighten us about the mechanism that made matter the victor.

Neutrinos come in three different types, called 1, 2 and 3. Each type is a particular mixture of three neutrino flavors, called electron, muon and tau. As neutrinos travel, their flavor-proportion changes in a process called oscillation.

Scientists compare rates of neutrino and antineutrino oscillation. The difference in oscillation rates could account for the matter-antimatter imbalance that ultimately led to our existence.

 

 

2. Shed light on the unification of nature’s forces

DUNE’s search for the signal of proton decay — a signal so rare it has never been seen, but is theorized — will move scientists closer to realizing Einstein’s dream of a unified theory of matter and energy.

spools

Today the world operates under four forces: gravity, weak, electromagnetic and strong. But once upon a time, immediately after the Big Bang, only one force governed the universe. Scientists have put forward different theories about the strength of the one force and how it broke apart. These calculations are captured in grand unified theories that attempt to describe three of the forces: weak, electromagnetic and strong.

In the beginning, when there was only a single force, the various particles we know today were all alike and responded to the one force in the same way. A fraction of a second later, the force broke apart, and now the various particle families respond to the different forces in different ways. The proton could provide a window into these responses.

Specifically, scientists can test these theories by searching for a proton's decay. The chance of observing this phenomenon is vanishingly small. But if they do spot it, it would narrow the field of possible grand unified theories and allow scientists to home in on a description of the original single force.

The Deep Underground Neutrino Experiment is designed to be sensitive to a number of types of proton decay. Scientists will look for them and possibly be put on the path to a theory of unification.

3. Learn more about neutron stars and black holes

DUNE will look for the gigantic streams of neutrinos emitted by exploding stars to watch the formation of neutron stars and black holes in real time and learn more about these mysterious objects in space.

neutrino factories

Nature's elements are forged in stars, and the heavier ones, such as carbon, oxygen and iron, are created primarily in the final death throes of a star. A star fuses lighter elements into heavier ones in its core until it can fuse no further and, unable to withstand its own gravitational pull, explodes in a supernova.

The exploding elements can become the seeds of future stars, and the formation of these stars clues us in to the evolution of our universe.

The very first evacuees from these luminous, explosive events are neutrinos, which are expelled as a dense group at a fantastic rate. If scientists are lucky enough to pick up the signal of neutrinos fleeing the supernova, heralding a recently exploded star, DUNE researchers could be alerted and take advantage of a rare opportunity to study an exploding star. They might even spy a black hole — the expected end product of some supernovae.

Learn more about neutrinos at the All Things Neutrino website.