IFIC seminar: "Neutrinos from Tokai to Kamioka: Oscillations, Interactions and the search for CP-Violation"

by Dr. Stephen Dolan (CERN)

Tuesday 15 Jun 2021, 12:00 → 13:00 Europe/Madrid

The precise characterisation of neutrino flavour oscillations offers a range of exciting opportunities to revolutionise our understanding of fundamental physics, not least of which is the potential to determine the value of the CP-violating phase (δCP) in the PMNS neutrino mixing matrix. The Tokai to Kamioka (T2K) experiment is able to provide the world’s leading constraints on δCP, alongside measuring other PMNS mixing parameters, by observing (anti)neutrino oscillations in an artificially produced ~1 GeV beam over a distance of 300 km.

Despite this considerable achievement, a precise evaluation of CP-violation in the neutrino sector will only be possible with a significant reduction of the associated systematic uncertainties. The most pressing of these concern the details of the neutrino-nucleus interactions which are observed in analyses of neutrino oscillations. In order to better confront such uncertainties, T2K is in the process of upgrading its near detector (ND280), which observes the neutrino beam close to its production point before any oscillations can occur. The upgrade consists of a new “super fine grained detector”, constructed from more than two million 1cm3 scintillator cubes, alongside surrounding time projection chambers and time-of-flight planes. These new detectors will vastly reduce particle tracking thresholds and will have an isotropic angular acceptance, thereby allowing a study of neutrino interactions with unprecedented accuracy. The excellent timing resolution and calorimetric performance also opens the possibility for new types of neutrino interaction studies.

In this seminar I will first present T2K’s latest analysis of neutrino oscillations and will demonstrate the critical role of neutrino-nucleus interaction modelling. I will then detail the upcoming upgrade to ND280 before showing its potential to directly confront the physics which drives many of the leading uncertainties in analyses of neutrino oscillations.