1/7/2024 0 Comments Macroplant ibrowse![]() ![]() Scientists know about three kinds of neutrinos, called ‘electron neutrinos’, ‘muon neutrinos’, and ‘tau neutrinos’, but a number of anomalous results had many scientists questioning if that is all there are. One of these anomalous results came from another experiment at Fermilab, called MiniBooNE. MiniBooNE scientists measured more electron neutrinos than they expected coming from Fermilab’s particle accelerators, and some proposed that it could have been evidence of interference from a new particle, the sterile neutrino.ĭr Duffy continues: ‘MicroBooNE set out to test the MiniBooNE anomaly, using a state-of-the art liquid argon detector that is able to show us neutrino interactions in exquisite detail. We looked for different types of electron neutrino interactions, and also some interactions of other neutrinos that could produce photons. Those could easily be mistaken for electron neutrinos in MiniBooNE, but we can tell them apart.’ Dr Duffy’s work has focused on predicting what the experiment would expect to see if there were no fourth neutrino. ‘We are looking for an excess of electron neutrinos – for more of these interactions than we expect,’ says Dr Duffy. ‘To do that, we need a really solid understanding of what we do expect, if our theories are right. I have worked on making sure we have a really solid prediction of what we expect to see, so we can say with confidence if we see something different.’īut that is not what MicroBooNE sees. Instead, the results are in line with the Standard Model of particle physics, scientists’ best theory of how the universe works. The data is consistent with what the Standard Model predicts – no more, no less. So, does that mean the sterile neutrino theory is over? It is hard to say, says Fermilab scientist Dr Sam Zeller, who served as MicroBooNE co-spokesperson for eight years. ‘We are not seeing what we would have expected from a MiniBooNE-like signal, neither electrons nor the most likely of the photon suspects. There’s something really interesting happening that we still need to explain.’ But that earlier data from MiniBooNE doesn’t lie. ‘This is a really exciting time for neutrino physics,’ concludes Dr Duffy. ‘We have a lot of questions about neutrinos and we are just getting to the point that we can really answer them. Our results make the light sterile neutrino hypothesis seem less likely but there is still a mystery we need to understand. So, if we want to understand the universe, we really have to understand neutrinos.’ Interested and want to learn more? It is exciting because neutrinos are so important to the makeup and evolution of the universe – it is possible that they could be the reason the universe exists at all. Read Fermilab’s news story about these results. Watch the Even Bananas video series about neutrinos, featuring UKRI Future Leaders Fellow at the University of Oxford Dr Kirsty Duffy. Take a virtual tour inside the MicroBooNE detector, developed by former Oxford researcher Marco del Tutto.Strictly speaking, the neutrino is not a singleparticle but rather comprises several species: the electron neutrino, the muon neutrino, and the tau neutrino. These particles are constantly transforming into each other in a process referred to as neutrino oscillation. It is assumed that neutrinos have mass this is to be determined in the KATRIN experiment, which started in 2019 at the Karlsruhe Institute for Technology (KIT). According to the results to date, the neutrino has a mass less than 1 electron volt. KATRIN could also be used to track down related species that have so far only been hypothetical: The sterile neutrinos. The heavier branch (mass in kiloelectronvolt range) is considered a candidate for dark matter and will be sought after a new detector is installed in KATRIN. New exclusion criteria for the light sterile neutrino Besides this, there could also a lighter sterile neutrino type. Quite a few experiments are looking for light sterile neutrinos (mass in the electronvolt range). It could also reveal itself in the KATRIN experiment.
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