The Intensity Frontier group at the University of Minnesota is leading research into the ‘ghostly’ neutrino particle and its behaviour.
What is a neutrino?
Neutrinos are one of the strangest particles we know of, and also one of the hardest to study. Due to their very low probability of interacting, we are forced to build very large neutrino detectors, which in turn forces us to use materials that are affordable and useful for detecting the signatures left by neutrinos. Unfortunately, this means that we need to understand how neutrinos interact with the materials used, whether that is water, plastic, iron, or cryogenic liquid argon.
What do neutrinos do?
Neutrinos will interact most commonly with individual protons and neutrons inside the nuclei of atoms and molecules. The interior of a nucleus is a murky place where quantum chromodynamics rules in an incalculable way, protons and neutrons are moving around and scattering off each other and producing virtual particles constantly. When a neutrino interacts with one of the protons or neutrons in a nucleus, it produces various particles, which must make it out of the incredibly dense nucleus in order to be observed by detectors.
What has been observed of the particles so far?
At the School of Physics and Astronomy, data from a number of neutrino experiments is being analysed to better understand what happens when neutrinos interact deep inside large nuclei.
Argon is particularly relevant as a future experiment experiment – DUNE (Deep Underground Neutrino Experiment) – will use 40,000 tons of liquid argon as its primary detector. DUNE will reveal if neutrinos and antineutrinos behave in the same way as one another. If they do not, they could have played a role in driving the domination of matter over antimatter in the early Universe.
Thus, to determine if this is the case, scientists need to be able to accurately predict the process of neutrino-nucleus interactions for both neutrinos and antineutrinos, and that requires very carefully measuring these interactions.
What other experiments are scientists planning to conduct?
Researchers are also involved in the design of new experiments and new detectors that will allow more precise measurements of all of the particles that make it out of the nucleus in these interactions.
One interesting avenue is the use of high-pressure gas instead of solids or liquids, as low-energy particles will be easier to detect in the lower density medium. Some of these new detectors may even be sensitive to interesting signatures from dark matter or other exotic theoretical particles and could transform our understanding of the Universe.
- Neutrino oscillations and their potential role in the early Universe
- Neutrinos as a probe of the nucleus
- Particle detector development