Stefan Soldner-Rembold, co-author of Fermilab’s (DUNE) Deep Underground Neutrino Experiment, explores the revolutionary discoveries the experiment should make possible.

The US Department of Energy’s National Fermilab Accelerator Laboratory is the US Particle Physics and Accelerator Laboratory that works to answer pressing questions about matter, energy, space and time. The Fermilab complex is currently undergoing a major upgrade, known as PIP-IIwhich will provide unparalleled levels of accelerator power to enable a number of revolutionary experiments.

Most importantly, the PIP-II upgrade will power the world’s most intense beam of high-energy neutrinos as part of the Deep Underground Neutrino (DUNE) experiment. As a major international collaboration of over 1,000 scientists from around the world, DUNE will seek to improve our understanding of neutrinos by potentially solving some of the greatest mysteries surrounding our universe.

Consisting of state-of-the-art particle detectors, the DUNE remote detector will be the largest of its kind ever created and will have the ability to record neutrino interactions with unparalleled precision. DUNE will be installed at the Long Baseline Neutrino Facility (LBNF) and will launch a neutrino beam across Earth from Fermilab in Batavia 800 miles to its destination at the Sanford Underground Research Facility in South Dakota.

To learn more about DUNE and the revolutionary discoveries it can allow, The innovation platform spoke with Stefan Soldner-Rembold, DUNE interlocutor.

Why is DUNE needed and what opportunities will it allow that was not possible before? Why is the current understanding of neutrinos so limited?

Neutrinos have proven that they can shed light on unknown questions about physics, beyond what is called the Standard Model of Particle Physics. Initially, an experiment conducted at the same mine where DUNE will be built observed fewer neutrinos leaving the Sun than expected. From this deficiency we unexpectedly learned that neutrinos have mass. However, the mass of the neutrino is insignificant and is much smaller than the mass of any other fundamental particle. This means that neutrinos have very special and strange properties and in some ways they behave and work with greater resemblance to photons.

One of the strange phenomena that neutrinos exhibit is known as neutrino oscillations. This means that a neutrino traveling through time and space can remarkably change its identity. We know that there are three different “flavors” of neutrinos – electronic neutrinos, tan neutrinos and muon neutrinos – and they can change from one type of neutrino to another as they travel from the Sun to Earth.

Related to this is a particularly interesting phenomenon known as ‘CP disorder’, which suggests that neutrinos and antineutrinos do not behave in the same way. This is something we’ve seen before about other standard model particles, but it’s never been seen with neutrinos. This could potentially be the key to understanding why there is an asymmetry of matter-antimatter in the universe.

The asymmetry of matter that we observe is obvious to us because we are made of matter. However, we assume that the original state of the universe was symmetrical with respect to matter and antimatter. There must now be an explanation for why the visible universe appears to be made entirely of matter, and neutrinos may be the answer to understanding this symmetry. DUNE can detect this effect and measure it accurately, greatly improving our understanding of how the universe came to be and what it looks like today.

One of the problems is that neutrinos don’t do much when they pass through matter. Every second, 1012 neutrinos travel through the tip of our finger and go unnoticed. In fact, a neutrino can pass lead in one light year without noticing it. To observe a neutrino in an experiment, we need to do three things.

First, we need to have a very intense source of neutrinos, because very few of them will actually interact. To achieve this, new types of very high-intensity accelerators need to be built, which is currently happening at Fermilab. Secondly, massive detectors are needed to allow scientists to study the small differences in behavior between neutrinos and antineutrinos, which is why DUNE is so large. The entire mass of the detectors must be instructed to be able to monitor neutrinos. Finally, since interactions are relatively rare, the detector must be protected from cosmic rays, as cosmic rays produce a lot of background noise. That’s why the DUNE experiment was located a mile underground in a former gold mine.

The neutrino is an intriguing and interesting particle.

What key questions do we hope DUNE will be able to answer?

The first observation I mentioned earlier was a violation of CP symmetry – understanding the difference between matter and antimatter by detecting a small difference in the behavior of neutrinos and antineutrinos. More generally, we hope to understand neutrino interactions and discover the basic physical laws that govern this part of the Standard Model.

DUNE is a neutrino observatory that not only observes neutrinos coming from Fermilab, but also neutrinos reaching us from a supernova or the Sun. Neutrinos produced by a supernova can provide an understanding of how a supernova works, while giving an idea of ​​how neutrinos work. The supernova emits more than 99% of its energy in the form of neutrinos.

Since neutrinos can travel through matter unhindered, the dynamics of how a supernova explosion works can be traced. The neutrino is not held back by anything that happens in a supernova, which allows good time resolution to measure what happens to this supernova in its various phases, which last a few seconds. DUNE is a great scientific experiment and these are just two of the scientific highlights.

Shiny liquid argon is seen inside the Liquid-Argon Purity Demonstrator, a 35-ton cryostat prototype used for early LBNF / DUNE tests.

What makes the DUNE collaboration unique?

A key factor is that this is a very large international project and in neutrino physics a project of this size has never been tried before. DUNE has more than 1,000 participants from 33 countries, and that’s exceptional.

What makes it special is that it is the largest international science project on American soil. While the CERN experiments are located in one place, this experiment extends across the continent, from Chicago to a mine in the Rockies.

At what stage is the project now and when is DUNE expected to be fully operational?

Excavation work is currently underway for the remote detector at the SURF laboratory in South Dakota. The rock is moving because while there is already a mine, an underground facility must be built so that the experiments can be housed in large caves. The final size of DUNE will be four modules, each filled with 17,000 tons of liquid argon and measuring about 60 x 20 x 20 meters.

The first components of the detector are currently being built. A lot of prototype and experimental work has been done at CERN, which is a project partner. CERN has not been involved in such a project abroad before. In the UK, we also started building large components for these first detectors at the Daresbury Laboratory in Cheshire.

We expect the first long-range detector modules to receive data at the end of this decade. Then the beam and the nearby detector in Fermilab will work in a few years. Over a period of several years, the opportunities will be further expanded and upgraded.

What specific areas of innovation can DUNE help facilitate?

DUNE is a research experiment that aims to understand how the universe works. The use of liquid argon to measure the interaction of particles is an extremely interesting technology and will be used in various experimental environments to study other phenomena – for example, in experiments looking for dark matter. The world’s leading machine learning machine is helping to develop computational and advanced algorithms that are needed to reconstruct neutrino interactions in argon.

Acceleration technology, which is being developed to produce high-intensity beams, has many potential future applications. The research and development of the accelerator, which takes place in places such as Fermilab, can be translated into applications and innovations in industry and medicine.

Stefan Soldner-Rembold, DUNE interlocutor.

Stefan Zoldner-Rembold
DUNE Interlocutor and Professor of Particle Physics
University of Manchester

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The DUNE experiment intends to unlock the mysteries of the neutrino

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