Ghostbusting
Both interactions are represented with Feynman diagrams. The muon production interaction is seen in fig.7 and the electron production interaction has already been encountered in the Davis experiment since solar neutrinos observed would be exclusively electron neutrinos.
In 1988 the first observed neutrino transition was announced at the Super-K, providing verifiable evidence for the neutrino flavour oscillation theory. This year, in order to increase the efficiency of the detector, an upgrade has been planned called SuperK-GD, inwhich gadoliniumwill be introduced to the ultra- pure water inside the tank. Gadolinium produces a bright flash of light when it absorbs a neutron; this would mean that the detector will be able to distinguish between anti-neutrinos and neutrinos, since in the rare instance that an anti-neutrino interacts with a proton in the water it should produce a positron and a neutron. Adding the gadolinium to the ultra-pure
(time)
Fig.7 - Muon production interaction
water represents a challenge since the water is constantly filtered to remove any impurities so clearly the added gadolinium could be filtered out. Fortunately, a prototype filtration system called EGAD was developed in 2018 that successfully remove any impurities while maintaining the gadolinium concentrations whilst not impairing the extreme transparency of the water required.
Future applications of neutrino science
In each cubic centimetre of space, it is estimated that there are over 300 neutrinos originating from the big bang. Since neutrinos rarely interact with matter, it should be possible to backtrack them to form a map of the very first stages of the universe that is extremely accurate. By using data from the Super-K and analysis of flavour oscillation, scientists are able to tell how far the neutrino has travelled and therefore its age. Very similar to CMBR 6 mapping, this could potentially be a giant leap in understanding the forces at play within 1 second of the big bang. However, there is one drawback. Cosmic neutrinos are thought to have extremely low energies and so would be far harder to detect than the younger and more energetic solar and supernovae neutrinos. One solution to this would be to supersize. The proposed Hyper-K detector would be able to hold 260,000 tons of ultrapure water and gadolinium, and it would use 40,000 ultra-sensitive photo detectors. This is an order of magnitude bigger than the Super-K and so would be far more sensitive. It aims to reveal insight into the four largest questions when considering neutrinos at the moment, mapping the early universe (as previouslymentioned), charge parity violation, 7 proton decay searches, 8 and finally determining the ordering of neutrino masses. 9 The Hyper-K collaboration will consist of 300 researchers from 75 institutes in 15 countries.
6 Cosmic Microwave Background Radiation: residual electromagnetic radiation originating from the early universe.
7 Whether there are fundamental differences between particles and anti-particles. 8 Whether a proton remains stable forever or has a half-life that is extremely large. 9 Whether neutrino masses increase with the same pattern as their lepton counterparts.
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