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Good morning, everybody. It's a real pleasure to welcome you to the Oxford Particle Physics, a Christmas lecture.

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We are one of the largest particle physics group in the UK and we have international reputation and we are playing a leading

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role in many experiments from the Large Hadron Collider to neutrino physics to the search for dark matter and dark energy.

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Before introducing our speaker,

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I would like to give you a very quick overview of our science and what we have done and what they've been doing the last year.

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So in 2019, the Large Hadron Collider was actually stopped, and we were doing like a lot of at CERN.

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There were a lot of refurbishing of the injector that are accelerating the protons in order to inject them in the Large Hadron Collider.

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And also, there is a lot of activities. There is a movie here that I cannot show because we had some computer problems this morning.

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And so I had to put my presentation in France's computer.

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But again, we are opening.

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For example, this movie shows the opening of the door if you want all of Atlas in order to do also some a lot of improvement in Atlas.

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And there is a lot going on also in LHC, be one of the other experiments that we do at the Large Hadron Collider.

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So in actually, you can see the movie starting on its own.

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Yeah, you can see that they are removing, you know,

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they're removing the shielding and hoping the opposite kavner so that we can access the experiment

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and do it in the Atlas experiment and do the improvement that we have planned during LS2.

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So in 2019, we have really focussed to study the Higgs boson and really say Higgs boson.

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It's really doing what is expected to do in the standard model.

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It is coupling and keeping the mass of to the W and the Z boson, the carrier of the lateral weakening of the weak interaction.

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And it's also displaying this new interaction, which is, of course,

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that you have a coupling that is this the known universe as coupling that is proportional to the mass of the particles.

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This graph show you see the coupling versus the mass of the particles.

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And just as a quick reminder, you know, the particles are divided in first generation,

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second generation and generation and the masses of the particle in the various generation up down quirk electron electron neutrino, Chalmers Drive.

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Strange Muon M. Neutrino. Top bottom Tao Tao Neutrino and W Z and the Higgs.

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Of course, you can see that the masses of the various quarks and leptons in the various generation increase.

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And in fact, this known fundamental coupling that is that you have a coupling does increase that wave the mass of the particle,

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which was predicted by the standard model.

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And as you can see here, this star, the Oxford Blue star, are the contribution of our student to this graph.

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And you see that we have contributed to the coupling to zad, to the W, to the B quark.

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And we are now starting to explore the coupling to this, to the second generation, to the muon,

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which is very tiny and it's very difficult to measure, but we expect to measure it soon at the Large Hadron Collider.

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Of course, in our class, we continues to look for new things. So here is just an event to show you.

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You know, we don't see quarks in our experiment.

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We see jets that remember the direction of the initial quark producing the odd scattering between the protons.

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And you can see here is the highest Mass Digest event, which, as an energy, a mass of eight trillion electron involved.

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So this is truly amazing.

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As you know, the law of physics predicts that in the end, the Big Bang, we add the same amount of matter and antimatter in the universe.

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So one of the ingredients to go from the universe at the beginning to the universe that we have now,

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which is dominated by matter, is a violation of a charged conjugation.

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When you change the particle to its antiparticle and parity, which is when you look at an interaction in a mirror.

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And so CP violation. So supersymmetry, which states that the laws of physics are the same for particle and antiparticle.

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And and there are the same for parity and the parity parity inversion.

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But again, we know already since nineteen sixty four is that the particles that contain the strange quirk lexicon do do violate ACP violation.

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This was discovered by a very famous experiment by Cunningham Fitch, which got the Nobel prise in 1980.

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And over the year, we have seen speed violation in the works sector, also in the B sector, for example.

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And just this year, the LHC B experiment as discovered a new place where you have CP violation, which is a zippy violation in the charm sector.

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This is a strangely beautiful measurement ZEV study the decay of the zero,

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which are measured that contains a charm quark two counts and 2lb pound palios.

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And they compare what happened four d0 with the zero bar, which is the antiparticle of the D0.

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And they looked at the millions of this event,

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and they find that this tiny effect at the 10 to the minus four level showing that the C.P is concern is violated in also in the travel sector.

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It's a very small amount and it matches the prediction of the standard model

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and is not enough to explain why the universe is dominated by matter today.

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So we are now looking at p violation in a different sector, which is the neutrino sector.

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And one of the experiments that we do is actually in Japan.

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And to see zippy violation, we have the neutrino beams produced a Jay Park in Japan, which are and you and anti-nuclear beam,

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which are directed towards the mountain in this region of Japan, where in a mine you have the Mamta and you have the super komakam that experiment.

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So you have a lot of water surrounded by photodetectors that enable you to see the channel

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of light deposited by neutrino and anti-new three anos antes detectors to really find A.

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Neutrinos are different from neutrino. You have to measure the flux with amazing precision.

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And one of our students is here at improving strategy in this measurement by a factor of two.

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And this is extremely interesting, actually, because in took this experiment.

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We brought he has a neutrino. He has an anti neutrino and the dots as experimental measurement.

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And you can see that actually the prediction without the CPE violation are not in agreement with the data as the one with CP violation.

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So we should really keep watching this because it's really a very promising result.

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So we are very exciting about neutrinos that really particles that always provide a lot of surprises.

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And we have two big experiments under construction. But Oxford is playing a big leadership, one in the US, which is called Yune.

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Where does the neutrino being?

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Will shine from Chicago, from Fermilab towards a mine in South Dakota and where they will be instrumented by really huge detector?

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And so at the moment, they started this excavation, which means that you have to take away, you know,

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eight thousand tons of rock to be excavated, to do the detector, to put the detector to detect a neutrino 1.5km underground is truly amazing.

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OK. And Oxford is leading the project in the UK, and we are providing a data position that will take the data from the carbon atom to the surface.

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The detector here are really huge. Here is a prototype detector under construction at CERN, which is called Proton Yoon.

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You can see here the size of a person so severe that really amazing.

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It will be an amazing project when it will be finished and the same in Japan.

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In Japan, again, the beam will be from Jay Park on this side of Japan.

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And then it was shown to the south, to the mountains where you will have a new detector,

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which is called IPA Mukunda, which is will be after megaton of water in in in this column.

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So I truly amazing project. We are also studying neutrinos at snow, no place, actually now, if you know,

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no got is experiment that was filled with 1000 tons of every water and was instrumental to this that neutrino oscillation.

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And this yielded the Nobel prise in 2015. And now there's no place was filled with water in and.

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And it allows the most precise measurement of nuclear decay.

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Up to now, you can see here are some of the results that were recently published.

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But the most interesting things that now the experiment is being filled with scintillating or loaded

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with real in order to understand if neutrino as the same particle as their own antiparticle,

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indicating that neutrinos are not Dirac particles but maiorana particle, this is really the next one of the big question about neutrinos.

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And Oxford, as an as develop this technique, and we've done a lot of study to understand how to load tellurium in this detector.

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So also, Elzbieta, this is another experiment that is studying dark matter, and this year it's an experiment that's been completed on the surface.

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And the experiment that started its travel underground again in the same mine in South Dakota, where Duna will be installed.

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So you can see how our amazing, you know, scope and the wildness of the physics that we that we cover.

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Apart from participating in the experiment, we also have an institute as part of particle physics,

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which is called the John Adams Institute, is named after one of the director of CERN.

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So say John Adams is a search of excellence for advanced and novel accelerator techniques,

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providing expertise, research, development and training the next generation of accelerator physicists.

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So as part of the John Adams, we are leading the construction.

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They they they.

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The understanding of how we could construct and build the new detectors at the new collider is that we need to advance in particle physics.

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And as you can see, we have a lot of possibility on the table,

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and we are currently trying to understand which one will be the one that we will choose.

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One of them is CliQ, which will be flooded in in phases.

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The first phase is about 10 km and CliQ is an electron positron collider.

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Then, and it will reach 380 g give.

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The second phase is about 30 km in Lanzer and it will reach 1.5 TB and the final is a final phase is 50 km and it will reach free TV.

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And as a plus or minus collider as been on under design in Japan.

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And we should know very soon if the Japanese will go ahead with it.

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But CERN is also preparing for what is called the future circular collider, which will be again an amazing facility.

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It will be here is the LHC, which is a 27 kilometre collider,

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and here is to actually see a 100 km collider that first will host a plus minus collision and then proton proton collision again to reach 100 TV,

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the highest energies ever in the world. So again, as I told you, we don't know yet which one of this project will be chosen.

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They are all very expensive, actually. As you can imagine, we are also building the new detectors for the upgrade of the LHC that will start in 2025.

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And so we are both building subpixel detectors and and the street detector for the new tracker of of of Atlas.

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And we are also building a lot of the upgrade for the LHC B experiment here.

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So now, before concluding, I would like to show you a few of the words that have been given to our faculties this year,

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al-Anbar as we see the Vice Chancellor Public Engagement with Research Award in 2019.

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Yes Developer, a programme of citizen science where citizen, especially young students,

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are going to look at the data of the LHC and study the Higgs boson.

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And this was an event that where you can see this as a student presenting their results at CERN and young

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ships is ahead of physics as we see the Chadwick Medal for illustration of the physics of Avi quirks,

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the development of the enabling instrumentation and the leadership of scientific collaborations.

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Again, not only our faculty to receive awards, this is one of our students is here to bicker and be as receive as artificial intelligence.

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Intelligent impact. The work from the Oxford Foundry and this group of students from Oxford has built a

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solution to present the barriers of bias in bias out in AI driven recruitment tools.

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The team won this award, and they were they won a weeklong trip to California,

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found spring to share that experience with other teams around the world.

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So merry Christmas to everybody in particle physics.

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And our present is really the Christmas lectures that we have today.

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I can only say that I'm really delighted to have a Francis here in Oxford.

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He's very distinguished. Is that yields, though?

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And Gregory Bright, professor at Wisconsin, as we see many prises, I just read a few as what he said about them.

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Price the European Physics Society prise for particle astrophysics and cosmology.

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The Smithsonian American Ingenuity Award for Physical Sciences in 2014.

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The Physics World The Breakthrough of the Year Award for making the first observation of

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Cosmic Neutrino in 2013 is an advisory role in many experiments in snow or to the Max Planck,

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to the ICES, our institute in Tokyo, to the US Particle Physics Prioritisation Panel to Abeka,

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which is a particle astrophysics advisory panel in Europe, is a member also of the Fermilab PSC.

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He wrote the book Where I Study My Particle Physics and You All the Old and Martin.

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And as you know, I mean, you always have a certain amount of, you know, it's always nice to meet the people that wrote the book where you studied.

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And I think that what is more amazing and you will hear about it today in this lecture is that he is really a true explorer.

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Yes, really enable a new part of physics in.

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On July 12 of 2018,

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the IceCube collaboration announced as the observation about 290 TBE neutrino and traces back to a small patch of the Orient constellation,

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where you add the activities of a black hole known as blazar to excess of zero five zero six.

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And this was really the birth of a new kind of astronomy where we have a new messenger which can help us study the universe.

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So please welcome Francis, all of them today. And.

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So it's a pleasure to be here. I actually gave the first lecture I've given in this theatre, I gave the show a lecture.

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I don't remember the year, but it's a long time ago and I remember that in the middle of the lecture, all the electronics fail.

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And I became I became an experimentalist in 30 seconds because I'm still a theorist.

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OK, so. I almost feel this is not appropriate for a Christmas lecture because we'll have

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to go on a long ride to a lot of sort of topics to cover 19 neutrino astronomy.

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I will tell you first what neutrino astronomy is. Then I will tell you what IceCube is.

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Then I will tell you how we discovered cosmic neutrinos and then we'll discuss what this actually means.

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And it's a pleasure to give this story because I.

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I'm talking to particle physicist or at least physicists, mostly, and so.

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You know, I share this talk with people like me who don't know any astronomy.

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So we'll have to, although this lecture in principle is about astronomy.

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So I'll I'll gently introduce astronomy.

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I first show you this slide because you probably recognise the microwave background, and I have to remind you that the universe is not empty.

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There are 411 microwave photons per cubic centimetre in the universe.

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This will be very important in this stock.

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Then what you have to know about astronomy is that you can change the energy of the photon over its wavelength of its colour.

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And so if I go to one electron volts photons, that's what the sky looks like.

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And this is to remind you, I will always use this projection of the universe.

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And so our home galaxy is the major axis of this ellipse.

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That's where we live somewhere out there. Then you can increase.

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Of course, we are mostly interested. We cannot relate to one if the photons.

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But so this is something we can relate to. This is the sky in one g.

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The photons. If you detect one photons, the sky looks like this and you see how bright our own galaxy is.

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And then you say, Well, you keep playing this game, right? It's what you do with accelerators.

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So you go to 10 to the 16 electron volts. And this is what the sky looks like.

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You see nothing.

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And that's interesting, actually, because it means if you list the wavelengths of light and you, you go to all the wavelengths the lenses do you,

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it means you come to a barrier where we have never seen the universe and you say, Well, how do you know there's something there?

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We know there is something there because we have actually seen cosmic rays that extend all the way to 10 to the 20 odd electron volts.

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But we have never seen like the dark side of the Moon. And so why is this?

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What is the physics? It's very simple.

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If you take this object very far away, it's a it's a particle accelerator that accelerates the cosmic rays we see,

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and it probably hopefully also emits photons.

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And so if you want to do astronomy with the photons, they never get here because remember,

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there are 411 microwave photons per cubic centimetre, so that photon will interact with one of the CMB.

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Photons produce an electron positron pair, and astronomy is finished.

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You cannot do astronomy, which charged particles, you know, dissolves probably produced the the protons.

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We see a tenth of the 20th electron volt. We know these particles exist for more than a century.

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We have no clue where or how they are accelerated. And that is because they are charged.

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So they are bending the magnetic field of the earth of our galaxy magnetic fields outside the galaxy.

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So they may produce there and we detect them there.

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So they don't tell us where they come from and the photons don't get here.

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So it's an old idea that goes back to the fifties, and nobody really knows the origin of that.

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Of course, you can solve all of this with neutrinos.

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Neutrinos reach us without being touched by magnetic fields or anything else from the beginning of time and from the edge of the universe.

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So they are really the ideal. Messenger, and they are identical to photons in this dark neutrinos have no mass stoke,

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the from the energies we are talking about are so high is that the mass they have is doesn't play any role, so they are exactly like light.

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The only problem is that they are difficult to detect and.

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They have another interesting property. This stock is going to be concentrated on the topic of finally finding the sources of cosmic rays.

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And so as everybody in this audience knows, neutrinos are produced by PI on scales that decay and to produce billions and chaos.

196
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You need protons. And so you only will see neutrinos from sources that if proton beams cosmic rays in this context.

197
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So if you make a map of the sky in neutrinos, you not only see the source of cosmic rays, you only see the source of cosmic rays.

198
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Now it's you know, I have to start by showing this slide and oops.

199
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So showing how how far this beam extends.

200
00:24:28,750 --> 00:24:36,490
And but what I am really interested in is this very high energy part of the cosmic ray spectrum.

201
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This tells you how many cosmic rays reach us from the universe.

202
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In fact, it starts with the Sun on the left and with the 10 to 20 one electron programme talking about here.

203
00:24:50,740 --> 00:24:57,670
By the way, that's 100 million TV for those who cannot relate to electron volts.

204
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And so. The real fascination for us, most of us are from this experiments,

205
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I think there's one like the one from the 300 people this one astronomer on this experiment.

206
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You know,

207
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I have to admit the only reason we are fascinated by this is that we want to know how nature constructs these accelerators and what they are.

208
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I remember when an experiment the new to detect that a particle that at the embassy of 300 million TV in 1991.

209
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So if you give me LHC magnets, I have to fill the orbit of Mercury to accelerate that particle.

210
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So I don't think that's how nature does it. But so how are cosmic rays accelerated?

211
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Well, if you think a little bit about the problem, you will see it's dramatic that they get this high energy.

212
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But if you look at the luminosity of the accelerators, it's very high as well.

213
00:26:04,630 --> 00:26:10,750
And so it's a real challenge to think of anything that can accelerate this cosmic rays.

214
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And so the only idea is that somewhere in the universe, you have to look for some huge amount of gravitational energy.

215
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And then your vendor meant a mechanism that somehow transforms one percent of this energy into accelerating particles that's called shock waves.

216
00:26:32,160 --> 00:26:38,760
And that's the last time I mentioned this subject. It's not appropriate for Christmas.

217
00:26:38,760 --> 00:26:47,520
And so where do you find a huge amount of gravitational energy stars that collapse?

218
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And so this is the standard model of cosmic ray physics. This is a stock that collapsed a few hundred years ago.

219
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It leaves a neutron star and then the shockwave expanding in the interstellar medium.

220
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You see these filaments there. That's where particles are accelerated in shocks.

221
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This can explain the cosmic rays in our own galaxy, the cosmic rays outside our galaxy.

222
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This doesn't work.

223
00:27:16,140 --> 00:27:25,530
But what does work is if you have a star that's more than eight solar masses, it will collapse in a black hole and then it will do the same thing.

224
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You saw the movie of it. The only thing is that you can get to higher energies 300 million TV, at least dimensionally.

225
00:27:35,190 --> 00:27:41,520
And it looks a bit different because the black hole is spinning, so it makes a beam of particles.

226
00:27:41,520 --> 00:27:46,980
It's not symmetric. Like this picture that's in every textbook.

227
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The only problem is there's no evidence for this. None whatsoever.

228
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And so. Are there other ideas?

229
00:27:57,290 --> 00:28:07,610
That's one of the ideas, maybe one and a half, I won't talk about the half one, but this remember, you need a huge amount of gravitational energy.

230
00:28:07,610 --> 00:28:11,270
Well, this is a galaxy almost like ours.

231
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It has a black hole at the centre like ours. And the only difference is that this black hole is active.

232
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And so it's eating its own galaxy. And you have huge amounts of.

233
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Of batter flowing on to that black hole.

234
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And so you have flows of particles, just like in an exploding star in this what's called the accretion disk, then this jet.

235
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And so you can set up shocks and accelerate particles in this stalk, the jet will actually play an important role.

236
00:28:52,740 --> 00:29:04,780
This galaxy has a magnetic field like ours and in some magic way in one turn of the black hole it will wind up.

237
00:29:04,780 --> 00:29:16,390
It will wind up the magnetic field and shoot it off perpendicular to its rotation along its rotation axis and produce like a particle B.

238
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And so here is where I'm going to enter the neutrinos.

239
00:29:21,700 --> 00:29:31,270
So imagine let's think about this jet. It accelerate if it's a cosmic ray source, it will accelerate protons.

240
00:29:31,270 --> 00:29:42,850
And these protons will move along the jet. But this black hole is surrounded by a mass of dust and light.

241
00:29:42,850 --> 00:29:51,500
You know, all this stuff blows flowing into the black hole will radiate and create huge radiation fields.

242
00:29:51,500 --> 00:29:59,880
Like. Typically, 10 electron volts, photons, and so this proton will interact with one of these photons,

243
00:29:59,880 --> 00:30:07,080
Makabayan to fire them, will decay into IMU on an IMU or neutrino, and the muon will further decay.

244
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And and I like Tom and. Neutrinos.

245
00:30:12,030 --> 00:30:21,780
So these are the neutrinos we want to detect, and then we know we have detected a proton accelerator now to bring this closer to home.

246
00:30:21,780 --> 00:30:28,710
This is how you make a neutrino beam at some. You have an accelerator, you shoot it.

247
00:30:28,710 --> 00:30:34,470
I think it was in a block of steel and the proton makes pions.

248
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It makes prions decay.

249
00:30:36,660 --> 00:30:47,740
The neutrinos come out and everything else actually is pretty much absorbed in the target that makes you fly this what's called a beam dump.

250
00:30:47,740 --> 00:30:50,920
And so we are looking for beam dumps in the sky.

251
00:30:50,920 --> 00:31:00,910
So it's exactly the same, you tap the electromagnetic energy of a black hole of a neutron star to accelerate particles.

252
00:31:00,910 --> 00:31:10,450
They are surrounded by dust, molecular clouds, radiation and so you have to get to produce neutrinos.

253
00:31:10,450 --> 00:31:18,610
And so the physics is well known. People as gamma gives a neutron and a pie, plus the five plus makes the neutrino.

254
00:31:18,610 --> 00:31:26,790
But remember, it also makes proton pi zero five zero decays into gamma rays.

255
00:31:26,790 --> 00:31:35,210
And these gamma rays will have similar energy to the neutrinos. So this will be an important topic, isn't this stop?

256
00:31:35,210 --> 00:31:41,430
So now the question is if you want to see cosmic accelerators, how big it?

257
00:31:41,430 --> 00:31:48,280
Experiment, do you need how big a neutrino detector? And I like to show this slide.

258
00:31:48,280 --> 00:31:55,150
Because it was presented at a conference in 2012 and we had billed IceCube.

259
00:31:55,150 --> 00:32:02,090
It was working for two years. We had to see nothing. And that's when you begin to worry.

260
00:32:02,090 --> 00:32:13,790
And so we showed this slide, OK. And so what it shows is that theorists for a couple of decades have tried to estimate the size of the detector,

261
00:32:13,790 --> 00:32:18,740
and they had all agreed that the size was one kilometre cube.

262
00:32:18,740 --> 00:32:28,070
You would detect 10 to 100 events per year if you build a fully efficient one kilometre cube neutrino detector.

263
00:32:28,070 --> 00:32:35,040
So what does this like? What do you see here? Well, first of all, this is the flux of neutrinos.

264
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This tells you how many neutrinos your experiment will see,

265
00:32:39,450 --> 00:32:47,940
but I've multiplied this flux by Energy Square because these accelerators, they don't produce monochromatic beams.

266
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They produce beams that where the energy, the number of particles falls as one of the energy.

267
00:32:55,560 --> 00:32:59,820
And so when I multiply by energy square,

268
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then the predictions of the theorists fall on the horizontal line and you can see there are the predictions supernova remnants.

269
00:33:08,790 --> 00:33:15,360
These are the things I showed on this slide. The dead, the exploding stars.

270
00:33:15,360 --> 00:33:21,720
There are the gamma ray burst. Those are. That's the one thing you saw the movie on.

271
00:33:21,720 --> 00:33:30,540
And this I will not talk about this were called the so-called guaranteed neutrinos, which we have never seen.

272
00:33:30,540 --> 00:33:34,380
So. What's the rest on this slide?

273
00:33:34,380 --> 00:33:39,450
Well, this is the bad news, that's the atmospheric military of flux.

274
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So the same cosmic rays, which we know and love will interact in will enter our atmosphere, interact with nitrogen and oxygen, make biomes and pilots.

275
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Make neutrinos and muons. And so these are called atmospheric neutrinos and atmospheric neutrons.

276
00:33:58,450 --> 00:34:08,450
All the physics is the same as what I described before. And you see, this is a logarithmic scale.

277
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So if you look up at the sky, you see notes, he knows all the time.

278
00:34:12,620 --> 00:34:18,560
You know, I stand the right scoop seasonality, you neutrino every five minutes.

279
00:34:18,560 --> 00:34:29,390
And these are these neutrinos. So it's like you are looking up at the sky and you see a cloud of neutrinos, except the cloud never goes away.

280
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And so that's the bad news.

281
00:34:33,350 --> 00:34:44,060
The good news is that we have measures this atmospheric neutrino beam over many orders of magnitude, which calibrated the experiment.

282
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Remember, we know how to measure chemistry, which is important for the rest of the talk.

283
00:34:49,640 --> 00:34:58,850
And then the other good news is if you come here to this hub of TV, that's the demarcation line.

284
00:34:58,850 --> 00:35:04,130
You see these floods disappear. And if you.

285
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Managed through the text on a routine well above 100 TV, it cannot come from the atmosphere.

286
00:35:10,730 --> 00:35:18,110
And so you can make a discovery with one event. Which we did, as I will show you.

287
00:35:18,110 --> 00:35:23,120
So remember the magic number from the TV?

288
00:35:23,120 --> 00:35:34,340
How do you detect neutrinos? Well, you saw. You probably all know about this experiment, you need water and filter multipliers, lie detectors.

289
00:35:34,340 --> 00:35:39,830
This is the SuperCam you can the experiment in the Japanese Alps.

290
00:35:39,830 --> 00:35:51,660
And it's a beautiful experiment. The problem with it is if you relate it to the previous slide, it's 10000 times too small.

291
00:35:51,660 --> 00:35:58,290
And so you have to build something that's 10000 times bigger, and that's what we did.

292
00:35:58,290 --> 00:36:07,660
It's called Ice Cube. How to do this is actually what's actually known since 1960.

293
00:36:07,660 --> 00:36:16,570
This is mostly Mark of and he I will not tell you what he said, but this is his idea.

294
00:36:16,570 --> 00:36:26,430
You go somewhere deep in the water, in the ocean, in a lake and you instrument.

295
00:36:26,430 --> 00:36:35,880
A volume of water we slide detect the multiplier tubes, then you detect neutrinos that are coming through the Earth.

296
00:36:35,880 --> 00:36:40,020
If you detect the particle coming through the Earth, it can only be a neutrino.

297
00:36:40,020 --> 00:36:44,760
No other particles can come to the Earth. What does he do?

298
00:36:44,760 --> 00:36:57,040
Well, it just goes through your detector. But at the end of this dramatic come the TV, about one in a million will cash into a nucleus.

299
00:36:57,040 --> 00:37:02,050
It doesn't see an atom. But it sees nuclei.

300
00:37:02,050 --> 00:37:14,620
And then what it will do is it will produce charged particles with physics that we all understand and love the standard model of particle physics.

301
00:37:14,620 --> 00:37:19,440
And these particles are charged, so they will.

302
00:37:19,440 --> 00:37:23,160
Produce light in the in the water.

303
00:37:23,160 --> 00:37:32,640
And if this is a on neutrino, it will create a mule and a mule, not these energies travels through the water for kilometres,

304
00:37:32,640 --> 00:37:40,170
tens of kilometres at very high energy, so you can actually detect them outside your instrument and volume.

305
00:37:40,170 --> 00:37:45,540
But also, when they travel through your detector, they will emit light.

306
00:37:45,540 --> 00:37:54,390
The moon travels at a speed of light. The water, the light in the water travels at three quarters of the speed of light.

307
00:37:54,390 --> 00:38:00,420
So it's like a speedboat that out comes the waves, and it makes a bow shock.

308
00:38:00,420 --> 00:38:05,520
And so if your photo multipliers can identify the shape.

309
00:38:05,520 --> 00:38:14,580
Of the strength of this is what it's called. Then, you know, the direction of the Moon and, you know, the direction of no, no train, no,

310
00:38:14,580 --> 00:38:21,310
and you not only have a detector, you have a telescope because you know where the neutrino came from.

311
00:38:21,310 --> 00:38:28,770
So remember, the IceCube is detecting neutrinos in the sky above Oxford.

312
00:38:28,770 --> 00:38:36,350
So. I think I said all that, so people try this in the 70s.

313
00:38:36,350 --> 00:38:44,810
They try to solve it. They try to construct an experiment like this twenty five kilometres off the

314
00:38:44,810 --> 00:38:52,190
coast of Hawaii and you see here a photo multiplier tube that's about to go,

315
00:38:52,190 --> 00:38:57,440
I think, four kilometres deep in the water. The experiment failed.

316
00:38:57,440 --> 00:39:07,910
In fact, it never got the funding to really succeed, and these people discovered a lot of the techniques that we are still using today.

317
00:39:07,910 --> 00:39:18,320
There was an experiment in Lake Baikal that actually did succeed, but it never became big enough to see cosmic neutrinos.

318
00:39:18,320 --> 00:39:27,980
And so the technology to do this in water has been developed by the untargeted experiment in the Mediterranean.

319
00:39:27,980 --> 00:39:37,280
They built a small detector like we did originally. We built something called Amanda and demonstrated techniques.

320
00:39:37,280 --> 00:39:43,780
So our idea was in the late eighties when we saw how.

321
00:39:43,780 --> 00:39:47,990
Difficult it was to deploy a detector in water. Right.

322
00:39:47,990 --> 00:39:58,270
And this is only the good idea we had. All the rest was luck, as you will see was that it was actually it's a counterintuitive idea.

323
00:39:58,270 --> 00:40:07,240
It's easier to put a sort of multiplier kilometres deep in natural Antarctic guys than to put it in water.

324
00:40:07,240 --> 00:40:13,180
And so that's what we did here. You see, that's the geographic south pole.

325
00:40:13,180 --> 00:40:22,450
So you are in the middle of Antarctica. And what made this experiment possible is that there is a research station there with cranes of bulldozers.

326
00:40:22,450 --> 00:40:33,040
Everything there is a runway. So everything comes in by plane and there is the Ice Cube project and the luck.

327
00:40:33,040 --> 00:40:40,150
We had this when we of course use, we started by looking if you've got an ice in a particle detector.

328
00:40:40,150 --> 00:40:49,090
This took about 10 years of R&D, and we found this fantastically clear ice once you were below one and a half kilometre.

329
00:40:49,090 --> 00:40:55,450
You cannot. You cannot construct in a lab.

330
00:40:55,450 --> 00:41:00,550
A piece of material that's more transparent to blue light than this ice.

331
00:41:00,550 --> 00:41:10,780
And so that was out of luck. And so we build a detector just by deploying photo multipliers one and a half kilometres

332
00:41:10,780 --> 00:41:16,690
between one and a half and two and a half kilometres to just do this physics.

333
00:41:16,690 --> 00:41:25,750
So we filled a km cube with five thousand two hundred sixty light sensors.

334
00:41:25,750 --> 00:41:33,440
So these are 10 inch. Basketball size, football multipliers.

335
00:41:33,440 --> 00:41:42,770
And they are equipped. They are, of course, within a pressure vessel of glass, and they are equipped with electronics,

336
00:41:42,770 --> 00:41:50,570
and the electronics transforms the light signal into digital signals.

337
00:41:50,570 --> 00:41:56,660
And these digital signals are sent straight to your computer wherever you are.

338
00:41:56,660 --> 00:42:04,270
Like this one? So if you could go into detector, it would look like this.

339
00:42:04,270 --> 00:42:09,510
So you would see kilometre long string with 60.

340
00:42:09,510 --> 00:42:16,980
Photo multipliers, one every 17 metres, if you go under 25 metres away,

341
00:42:16,980 --> 00:42:28,650
you will find another string and then under 25 metres away, another one and 86 of these strings form from the detector.

342
00:42:28,650 --> 00:42:33,910
Now. Yeah.

343
00:42:33,910 --> 00:42:39,880
So. I won't spend too much time of it, but you must.

344
00:42:39,880 --> 00:42:44,470
That's the beauty of this detector. You know, actually no detector.

345
00:42:44,470 --> 00:42:57,430
Each of these photo multipliers, whenever it detects light, it tells you in a digital form how many photons you'd see and at what time puts digitises.

346
00:42:57,430 --> 00:43:04,360
That picture put an absolute time stamp on them and sends it to the computers at the surface.

347
00:43:04,360 --> 00:43:11,470
And these computers detect continuously all this light signals and put them together in a chain of events.

348
00:43:11,470 --> 00:43:17,260
So I'm a theorist, so you may wonder whether this is filled by now.

349
00:43:17,260 --> 00:43:24,580
So that's a picture you deploy strings in December and January.

350
00:43:24,580 --> 00:43:30,460
It's too cold otherwise. And so you see here, 20 cables were deployed.

351
00:43:30,460 --> 00:43:34,750
They go through despite peering through this two story building.

352
00:43:34,750 --> 00:43:39,310
And this two story building contains computers.

353
00:43:39,310 --> 00:43:46,610
Now everybody now is. I think asking the question, how do you put this in the eyes?

354
00:43:46,610 --> 00:43:54,650
That was actually the hardest part, and that's where we actually were very proud of this idea.

355
00:43:54,650 --> 00:44:03,320
So here is a movie. So the first 90 metres is snow, so you just melted.

356
00:44:03,320 --> 00:44:07,760
Then comes in what we call the Hot Water Grill.

357
00:44:07,760 --> 00:44:17,450
And so it's a nozzle that just puts out boiling water under pressure and it falls by gravity and melts its way.

358
00:44:17,450 --> 00:44:29,820
So there is no hole. It changes water into ice, and after two days, you have a pipe in which you can deploy for the multipliers and.

359
00:44:29,820 --> 00:44:35,700
A fleet of liquid water. And so this takes about five megawatt.

360
00:44:35,700 --> 00:44:44,850
It's about 40 car wash seats, that's what it is. And so you see the whole system is like a circus train.

361
00:44:44,850 --> 00:44:50,700
It's deployed on on on sleds. And that's the drill tower.

362
00:44:50,700 --> 00:44:56,030
This is a two and a half kilometre hose. It's built near father.

363
00:44:56,030 --> 00:45:06,930
It's actually a marvel of technology. This thing. It's about that big, and it can hang over two and a half kilometres without collapsing.

364
00:45:06,930 --> 00:45:12,410
And here you see the generators that by normal fuel drive.

365
00:45:12,410 --> 00:45:21,270
The 40 car wash heaters that provide the 4.8 megawatt and so after two days.

366
00:45:21,270 --> 00:45:33,240
Your drill comes out and ICE is an insulator, so that water remains liquid for hours, so we build it so that the whole last like 30 hours.

367
00:45:33,240 --> 00:45:35,340
And so then you move on.

368
00:45:35,340 --> 00:45:49,070
But waiting out these boxes and they contain the six the optical modules, and so they will be deployed, as you will see in the next frame.

369
00:45:49,070 --> 00:45:54,500
So these are the first to multiply as in the crash of vessels. So this is the cable.

370
00:45:54,500 --> 00:46:09,170
This is a cable where you bring down the high voltage, but also bring back up the digital signals you see when you are at no deal number 60.

371
00:46:09,170 --> 00:46:17,780
There is a 600 pound weight at the bottom. You let the string drop to the bottom and wait until the ice freeze and you take data.

372
00:46:17,780 --> 00:46:22,910
That's the idea. And so back to the physics now.

373
00:46:22,910 --> 00:46:27,650
So if you didn't get it yet, this is a muon entering the detector.

374
00:46:27,650 --> 00:46:33,290
This is the lighted admits the strength of radiation. And you see, this is the response.

375
00:46:33,290 --> 00:46:41,690
Each of these black dots is a light sensor, and you can with your high reconstruct the direction of the Moon.

376
00:46:41,690 --> 00:46:51,660
So the detective sees. Neutrinos produced in the atmosphere all over the Earth.

377
00:46:51,660 --> 00:47:04,200
It detects Mulan's cosmic Ray Muons coming from the back from the southern hemisphere, and so I will show you a movie.

378
00:47:04,200 --> 00:47:14,000
This is the detector detecting muon tracks. You remember it collects these signals and makes them into tracks.

379
00:47:14,000 --> 00:47:26,270
And you see the movie repeats at some point you see these dramatic museum bundle come through raised by a very energetic cosmic ray.

380
00:47:26,270 --> 00:47:31,100
This movie is 10 milliseconds long.

381
00:47:31,100 --> 00:47:42,600
And so. The bottom line is that we detect 100 billion Muslims every year, 3000 per second.

382
00:47:42,600 --> 00:47:51,390
Hundred thousand atmospheric neutrinos per year, one every six minutes, it's now more like one every five minutes,

383
00:47:51,390 --> 00:48:01,410
and I'll give you the answer we see in this mess, we detect 120 mu on neutrinos per year.

384
00:48:01,410 --> 00:48:07,230
And so how did we manage to do this?

385
00:48:07,230 --> 00:48:19,460
So we did it the way Berkoff told us. Here is a picture of an event to remember, so each of the dots, you cannot actually see the dots.

386
00:48:19,460 --> 00:48:27,510
Our licensors and here you see the response. This is a MEU entourage that comes from 11 degrees below the horizon.

387
00:48:27,510 --> 00:48:35,790
So it comes through the Earth near the horizon and it enters your detector here and you see the colour.

388
00:48:35,790 --> 00:48:41,400
You follow the rainbow. So it comes. Indeed, unlike the previous one, it comes through the Earth.

389
00:48:41,400 --> 00:48:59,950
It's a neutrino. The demarcation line was some the TV, so here this remember we can measure energy, this the energy of this event is 2006 on the TV.

390
00:48:59,950 --> 00:49:08,080
And so this is typically the event that represent the Five Sigma Discovery with one event actually only 4.6,

391
00:49:08,080 --> 00:49:19,150
but so and this actually this this mewe on lost energy before we then turn your detector and current energy out.

392
00:49:19,150 --> 00:49:29,120
So it's real energy is much higher than that. So the neutrino as an energy of somewhere between five and ten thousand TV.

393
00:49:29,120 --> 00:49:39,080
And so we actually recently discovered an event that has twice the energy of this one that is Five Sigma.

394
00:49:39,080 --> 00:49:48,620
So what you saw is exactly the picture that we saw Mew on a train and we saw the museum go through the detector.

395
00:49:48,620 --> 00:49:54,020
In fact, we saw about three years of data we have.

396
00:49:54,020 --> 00:50:03,050
We had discovered five of those 50 cosmic neutrinos in the background of three hundred forty thousand.

397
00:50:03,050 --> 00:50:05,240
And so I don't show the data.

398
00:50:05,240 --> 00:50:16,250
You only see the blue is the atmospheric background, which of course, we not only detect, we can calculate and extrapolate and you see the data.

399
00:50:16,250 --> 00:50:25,090
This is the usual. This is actually an event. PIN number of events per neutrino energy.

400
00:50:25,090 --> 00:50:33,130
And here you see the actual data event I just showed you with this one.

401
00:50:33,130 --> 00:50:41,440
And so remember E to the minus two, it's actually to the minus 2.1 nine in this plot.

402
00:50:41,440 --> 00:50:47,260
And so what you see is exactly describe the atmospheric neutrino flux.

403
00:50:47,260 --> 00:50:54,720
And then at the the TV, the deviation, the flat spectrum.

404
00:50:54,720 --> 00:51:06,640
So. This is actually not how we discovered McMurtry knows we went on a tangent that we kind of knew about it was not a surprise.

405
00:51:06,640 --> 00:51:11,620
But what happened is that we found two events.

406
00:51:11,620 --> 00:51:23,770
One of them was this one. And. You know, every Thursday, the people in the collaboration get together on the phone and this goes on for hours.

407
00:51:23,770 --> 00:51:30,760
And everybody sits in their offices doing email and because this is incredibly boring.

408
00:51:30,760 --> 00:51:38,920
And so I remember when someone from our collaborators in Japan showed this event,

409
00:51:38,920 --> 00:51:45,010
and I knew instantly we had this cosmic neutrinos because I'm an optimist.

410
00:51:45,010 --> 00:51:51,760
But what I mean is that this event, you know, you can tell it's contained in the detector.

411
00:51:51,760 --> 00:51:54,250
It's a total absorption calorimeter.

412
00:51:54,250 --> 00:52:02,260
And with the training we had by then, I could tell from the size of the event this is a thousand TV, not from the TV.

413
00:52:02,260 --> 00:52:07,030
And you say, Well, there's no new track. No, there is no MEU on track.

414
00:52:07,030 --> 00:52:17,770
That is because this is an electronic trino. So the neutrino makes instead of rmu on an electron and an electron showers in the eyes,

415
00:52:17,770 --> 00:52:24,220
it makes an electromagnetic shower, which is about the size from here to the wall.

416
00:52:24,220 --> 00:52:30,580
And so a shower that began a kilometre cube detector is a point source of light.

417
00:52:30,580 --> 00:52:38,760
And so this oops, where did. So.

418
00:52:38,760 --> 00:52:45,660
So it's like you turn on a light bulb in your detector, and that's what you saw.

419
00:52:45,660 --> 00:52:50,220
You just this total is practically symmetric light pool.

420
00:52:50,220 --> 00:53:00,540
And so. I superimposed this event on the data centre, which is in Madison, Wisconsin, just to reset the scale.

421
00:53:00,540 --> 00:53:06,510
This is the lake, by the way, like Mendota. You should call me if you haven't been there.

422
00:53:06,510 --> 00:53:14,890
And so in Oxford, this would be about the size of five six city blocks.

423
00:53:14,890 --> 00:53:23,230
And this is important because 300 census report that light in this event.

424
00:53:23,230 --> 00:53:32,350
So we see about 100000 photo electrons. And we know where each of this is two two nanoseconds, which is about that much.

425
00:53:32,350 --> 00:53:40,150
So with this information, you can actually reconstruct the direction of the neutrino, not just its energy.

426
00:53:40,150 --> 00:53:51,650
And so this is a simulation of the event. And you see it's totally symmetric because it's red here, yellow there now, yellow here, blue, dark green.

427
00:53:51,650 --> 00:53:56,640
Remember, the colour is the time of the photons. So this.

428
00:53:56,640 --> 00:54:05,410
Neutrino came from here. And so the photons reach of detectors first, they're then in the back.

429
00:54:05,410 --> 00:54:11,770
And so from that information, you can reconstruct the direction not as well as the new ones.

430
00:54:11,770 --> 00:54:18,220
So we found two of those events when we were looking for something totally different.

431
00:54:18,220 --> 00:54:22,660
Pure serendipity. And so but now you've got the idea.

432
00:54:22,660 --> 00:54:31,900
Use the experiment as a Soviet, as a calorimeter and just look at events that interact inside the detector like this one?

433
00:54:31,900 --> 00:54:38,800
We had two years of data. And I remember, you know, there was this discussion that went on forever.

434
00:54:38,800 --> 00:54:43,570
We discovered cosmic neutrinos are not. We decided we had not.

435
00:54:43,570 --> 00:54:52,810
But so you go through the two years of data and see if you can find more of these events that interact inside the detector.

436
00:54:52,810 --> 00:54:58,210
We found 26 more. And then we published we actually.

437
00:54:58,210 --> 00:55:09,820
I should tell you that since 1990, when we start thinking about that, we were actually using neural nets to separate backgrounds from Signal.

438
00:55:09,820 --> 00:55:16,810
We were doing what's now called artificial intelligence, boost the decision to everything you want.

439
00:55:16,810 --> 00:55:21,430
And that's how we actually separate neutrinos from the signal.

440
00:55:21,430 --> 00:55:25,000
And so I won't go in how we do this analysis.

441
00:55:25,000 --> 00:55:33,310
But at some point, a graduate student in Madison pointed out to us that you see the signal, you just have to plot the data.

442
00:55:33,310 --> 00:55:41,610
And so in this plot, you see the.

443
00:55:41,610 --> 00:55:50,130
The vertical axis is the number of events. Now we have a free to reach them so that no light comes in the detector to make

444
00:55:50,130 --> 00:55:55,290
sure that the light comes from a train or that interact inside a detector.

445
00:55:55,290 --> 00:56:01,730
So this tells you how many photons come inside the detector, and the answer has to be zero.

446
00:56:01,730 --> 00:56:11,040
And this tells you the number of photons in the event, so this is high energy, this is low energy, so.

447
00:56:11,040 --> 00:56:18,460
You want to be somewhere on this side of the plot, and if you look, there is the signal.

448
00:56:18,460 --> 00:56:23,860
And this is only one year of data. We have 10 years every year looks the same.

449
00:56:23,860 --> 00:56:34,270
And so but after two years, we finally discover decided we discovered cosmic neutrinos and published in 2013.

450
00:56:34,270 --> 00:56:40,030
So the question was, by the way, it was another graduate student who was, of course,

451
00:56:40,030 --> 00:56:46,120
still looking for new neutrinos coming to the Earth, and we only beat him by a few months.

452
00:56:46,120 --> 00:56:54,830
He also discovered cosmic neutrinos independently of these two methods consistent, and the answer is yes.

453
00:56:54,830 --> 00:57:00,710
Here is the flux we observe.

454
00:57:00,710 --> 00:57:06,290
This is again, this is square flux plot as a function of energy.

455
00:57:06,290 --> 00:57:09,800
And you see here, that's the cosmic neutrino flux.

456
00:57:09,800 --> 00:57:19,100
This measurement, the data points are actually the measurements of the shower friends that I talked about last.

457
00:57:19,100 --> 00:57:29,660
So they are electron and town that he knows. And so the the pink is the spectrum measure with the muons coming through the Earth.

458
00:57:29,660 --> 00:57:34,430
And you see these are totally compatible.

459
00:57:34,430 --> 00:57:43,010
So this actually assumes now, you know, neutrinos oscillate, so if we detect sources way beyond the Sun,

460
00:57:43,010 --> 00:57:50,150
by the time they arrive at IceCube, they come in equal flavours as many new new moon tile.

461
00:57:50,150 --> 00:57:57,680
And so we make this triangle like that tells you the fraction of new tile.

462
00:57:57,680 --> 00:58:01,490
So this is all new tile, the fraction of new Mew.

463
00:58:01,490 --> 00:58:07,580
So this is all new Mew. This is all new tile, all new Mew.

464
00:58:07,580 --> 00:58:18,480
All new. So let me go back one.

465
00:58:18,480 --> 00:58:29,270
Yeah. So you expect expecting this plot to end up in the centre of gravity, and this is where we are at the moment.

466
00:58:29,270 --> 00:58:32,900
And so we are actually doing that, despite of what I said,

467
00:58:32,900 --> 00:58:39,950
we are doing oscillation measurements, but not that one jersey at a million times higher energy.

468
00:58:39,950 --> 00:58:47,450
And sadly finding the same good result, however, you notice that the Zika virus are pathetic.

469
00:58:47,450 --> 00:58:51,230
And so you actually want to do this measurement.

470
00:58:51,230 --> 00:58:55,310
I'm going to I'm going to spend five minutes on particle physics.

471
00:58:55,310 --> 00:59:01,610
I cannot resist it. And then I'll come back to looking for things in the sky.

472
00:59:01,610 --> 00:59:07,370
So. You have to end up here in this diagram.

473
00:59:07,370 --> 00:59:11,810
But, you know, we don't really know what the beam dump is like.

474
00:59:11,810 --> 00:59:18,180
So if you imagine all possible beam dumps. And you stand three, No.

475
00:59:18,180 --> 00:59:30,000
Three, no flavour oscillations, you can compute that you have to end up in this diagram in this triangle that if analysed for the neutrinos to decay,

476
00:59:30,000 --> 00:59:34,620
which they may or may not from where we are detecting them.

477
00:59:34,620 --> 00:59:44,140
So the interesting thing is if we can do this measurement and we don't end up in this triangle anywhere else.

478
00:59:44,140 --> 00:59:53,650
On the plane in the big triangle, we have discovered a new neutrino physics, which is really why everybody these days is doing neutrino experiments,

479
00:59:53,650 --> 01:00:07,100
and we actually are in the middle of building an experiment that can measure this measurement probably even a little bit better than the screen.

480
01:00:07,100 --> 01:00:15,170
Ellipse that you see there, Blue, the way we are doing this is we started is actually a long time ago.

481
01:00:15,170 --> 01:00:24,080
We are putting things inside Ice Cube to create a detector in the bottom centre

482
01:00:24,080 --> 01:00:30,920
that is more instrumented and that becomes a respectable neutrino detector,

483
01:00:30,920 --> 01:00:39,770
not just the telescope. And so this measurement has this pathetic air box because these events look like this.

484
01:00:39,770 --> 01:00:44,630
Compare that to the events I just showed you that we really can reconstruct,

485
01:00:44,630 --> 01:00:51,740
but with what we are going to deploy in two years, this event will look like that.

486
01:00:51,740 --> 01:00:57,080
And that will allow us to do this measurement. And I think it's very interesting.

487
01:00:57,080 --> 01:01:05,520
By the way, about time neutrinos.

488
01:01:05,520 --> 01:01:16,170
You know, time neutrinos where discover that Fermilab a long time ago and the way you discover them is the Tao you make a tiny neutrino comes in,

489
01:01:16,170 --> 01:01:25,180
it makes a tower and the tower decays. And so it leaves about one millimetre at Fermilab.

490
01:01:25,180 --> 01:01:32,470
And so with an emulsion, you can actually see it interact. And you can see the Tainui produces decay.

491
01:01:32,470 --> 01:01:37,600
Well, this is a lifetime. A lifetime is linear in energy.

492
01:01:37,600 --> 01:01:43,930
So at a thousand TV, this mm becomes.

493
01:01:43,930 --> 01:01:46,280
50 metres.

494
01:01:46,280 --> 01:02:00,140
And so you saw that we actually have separated Newey from Newtown in this triangle, so we look through the data and there must be some Tainui events.

495
01:02:00,140 --> 01:02:06,110
And this is what a tyre. This is not the event. This is what the tyre events should look like.

496
01:02:06,110 --> 01:02:12,860
You see the tire interacts here. The tile then lifts 50 metres in the case.

497
01:02:12,860 --> 01:02:18,950
And so indeed, we found one real event, one candidate event.

498
01:02:18,950 --> 01:02:31,130
And so here you see the event. Oops.

499
01:02:31,130 --> 01:02:38,000
And you cannot tell it's a town that lifts 17 metres, which we certainly can tell.

500
01:02:38,000 --> 01:02:45,260
And you can see you cannot see it in this display, but go and look, for instance,

501
01:02:45,260 --> 01:02:52,700
at this, this particular digital optical module you see here in this photo multiplier.

502
01:02:52,700 --> 01:02:58,670
Here, you see it first detects the photons that are made when the tower interacts.

503
01:02:58,670 --> 01:03:08,930
And these are the photons when the tower decays. And you know, you can do this in every of these pictures.

504
01:03:08,930 --> 01:03:14,810
So the interesting thing is the atmospheric new towers.

505
01:03:14,810 --> 01:03:21,620
Of course, the atmosphere doesn't make new towers of this energy.

506
01:03:21,620 --> 01:03:26,930
So this event, again, is an independent discovery of cosmic neutrinos.

507
01:03:26,930 --> 01:03:39,430
Now, I cannot resist showing you this event. This is of no interest to astronomy, but I do know amongst particle physics audience this is an event.

508
01:03:39,430 --> 01:03:48,310
That. Interact slightly altered side the detector, but it's so big that you can reconstruct it.

509
01:03:48,310 --> 01:03:55,590
And in fact, what it is is I told you the neutrinos only interact with.

510
01:03:55,590 --> 01:04:04,620
The nuclei, there's an exception to that when an electronic trino interacts with an atomic electron.

511
01:04:04,620 --> 01:04:14,210
It can make a real W 8g v sound w and then decay into two jets.

512
01:04:14,210 --> 01:04:26,390
This was actually proposed as a way to look for the W by Glasgow in 1959, when he was a postdoc of Niels Bohr in Copenhagen.

513
01:04:26,390 --> 01:04:33,870
And so what it looks like is this is the cross section for neutrinos as a function of energy.

514
01:04:33,870 --> 01:04:42,500
And so when you come to this. W production mechanism, you have an increased probability,

515
01:04:42,500 --> 01:04:48,500
and so you can go and look of these events, but they only exist at that one particular elementary.

516
01:04:48,500 --> 01:04:55,160
And so this is the construction of the energy of this event and we got all excited.

517
01:04:55,160 --> 01:04:59,210
You know why? Our energy collaboration.

518
01:04:59,210 --> 01:05:07,770
That's correct. So.

519
01:05:07,770 --> 01:05:13,770
We are thirty five years, thirty six, like to discover the W.

520
01:05:13,770 --> 01:05:23,560
Back to astronomy. So this is one year of data.

521
01:05:23,560 --> 01:05:28,390
And hope not that this is one year of data.

522
01:05:28,390 --> 01:05:34,270
And you see there are a hundred thirty eight thousand neutrinos.

523
01:05:34,270 --> 01:05:40,120
And in this map, I can tell you there are 20 cosmic neutrinos mew.

524
01:05:40,120 --> 01:05:42,520
This is just the mule neutrinos.

525
01:05:42,520 --> 01:05:52,390
You see a structure in this map that has to do with the fact that the Earth is more transparent to neutrinos here than there.

526
01:05:52,390 --> 01:05:58,390
These neutrinos already don't come through the artisanal at these energies.

527
01:05:58,390 --> 01:06:05,230
So we use this to measure the neutrino cross-section and unfortunately find the right answer.

528
01:06:05,230 --> 01:06:12,920
And so you cannot. First of all, you don't see the galaxy, but you say you're mostly looking at background.

529
01:06:12,920 --> 01:06:19,060
So let me select just the high energy neutrinos and you come to the same conclusion.

530
01:06:19,060 --> 01:06:29,410
We don't see our galaxy. This was a big surprise. You are first supposed to see the nearby accelerators and then the ones far away.

531
01:06:29,410 --> 01:06:36,760
And so we have now 10 years of data, and something exciting happens for the first time,

532
01:06:36,760 --> 01:06:42,900
we have actually evidence that this map is not totally symmetric.

533
01:06:42,900 --> 01:06:48,720
And then you ask, it's a three point two sigma effect.

534
01:06:48,720 --> 01:06:53,100
And so it's not a discovery, but you ask why does this happen?

535
01:06:53,100 --> 01:06:57,720
It is because four souls stick out of this map.

536
01:06:57,720 --> 01:07:02,250
And the biggest one is NGC thousand sixty eight.

537
01:07:02,250 --> 01:07:07,820
The second one is the excess of five or six, et cetera.

538
01:07:07,820 --> 01:07:18,830
And so this is the first hope, actually, that by more data, we are working very hard on improving our angle of resolution,

539
01:07:18,830 --> 01:07:26,630
which is like half degree or so to to try to find these sources.

540
01:07:26,630 --> 01:07:30,860
But in any case, let me conclude where we are now.

541
01:07:30,860 --> 01:07:36,650
So with this a diffuse flux, we saw more evidence for sources.

542
01:07:36,650 --> 01:07:41,990
We cannot see our galaxy. And the first question I'm going to ask.

543
01:07:41,990 --> 01:07:50,660
I told you there is for every thousand TV Norteno, there's a thousand TV gamma ray that nobody has ever seen.

544
01:07:50,660 --> 01:07:57,170
But you can already guess why this is this. We didn't lay awake at night about this.

545
01:07:57,170 --> 01:08:04,880
This is the slide right. There is a p by zero for the five plus that makes these Norteno events.

546
01:08:04,880 --> 01:08:16,040
And so really, what this source is doing is admitting by zeros in gamma rays as the same time that he meets PI pluses and no Tino's.

547
01:08:16,040 --> 01:08:20,120
And you know the balance. Remember, it's called dice of spin.

548
01:08:20,120 --> 01:08:25,400
You cannot change the ratio between PI zeros and five plus PI minus.

549
01:08:25,400 --> 01:08:32,720
And but you know the answer these gamma rays don't get you at least not with the energy.

550
01:08:32,720 --> 01:08:38,150
They interact with the microwave background. But then the picture doesn't stop.

551
01:08:38,150 --> 01:08:44,000
These electrons and positrons will radiate and the photons will interact again.

552
01:08:44,000 --> 01:08:57,140
And this is QED. We know how to compute this. So you develop an electromagnetic shower in a microwave photon background.

553
01:08:57,140 --> 01:09:05,960
And so these gamma rays are high here with G.V. Energy, no times on TV energy.

554
01:09:05,960 --> 01:09:12,470
And so you can calculate how many gamma rays come out of this process.

555
01:09:12,470 --> 01:09:16,550
So here is the neutrino data at a very early stage.

556
01:09:16,550 --> 01:09:22,190
This was the first time Marc Gasol actually I saw him make this float.

557
01:09:22,190 --> 01:09:27,140
And so here is the fit to our early data.

558
01:09:27,140 --> 01:09:29,450
And so what you do is,

559
01:09:29,450 --> 01:09:38,600
you say I have the same number of gamma rays and then you dump them in the microwave background from the computer and you see what comes out,

560
01:09:38,600 --> 01:09:44,020
what comes out is this. You see.

561
01:09:44,020 --> 01:09:55,290
And we have an instrument, the satellite that detects these gamma rays and what it sees is exactly what you predict exactly mean to factor two wolf.

562
01:09:55,290 --> 01:09:59,710
So it depends, you know, I can play with this calculation.

563
01:09:59,710 --> 01:10:06,890
I can do all kinds of things I can, you know, extrapolate it all.

564
01:10:06,890 --> 01:10:12,820
Modelled in different ways, but the conclusion is that.

565
01:10:12,820 --> 01:10:19,050
The energy in the universe, in neutrinos and gamma rays is the same.

566
01:10:19,050 --> 01:10:31,110
Up to a factor. Actually, I bet my wallet that the energy neutrinos is higher and there's no evidence in the data, but I won't go into that.

567
01:10:31,110 --> 01:10:42,210
And that came, of course, as a shock because astronomers had ignored cosmic rays as some exotic phenomena that didn't play a role in the universe.

568
01:10:42,210 --> 01:10:51,280
That signal cannot be dormant anymore. So this is a picture of the family satellite.

569
01:10:51,280 --> 01:10:58,400
And so I remind you, it's a photodetector bill that slack her.

570
01:10:58,400 --> 01:11:03,830
Flying above the atmosphere. So remember.

571
01:11:03,830 --> 01:11:10,310
The advances astronomers are, have they know what they are looking at?

572
01:11:10,310 --> 01:11:15,610
And so you may think at this point we are looking at the same objects.

573
01:11:15,610 --> 01:11:21,280
And so what do they see? Will they see something called blaze of?

574
01:11:21,280 --> 01:11:25,330
And these are kind of like the seagulls of the universe, you know,

575
01:11:25,330 --> 01:11:31,240
they you see them everywhere these days and the channel, you want to get rid of them.

576
01:11:31,240 --> 01:11:39,190
To see more interesting birds. But place where this jet is actually pointing at the Earth.

577
01:11:39,190 --> 01:11:45,350
The jet of the black hole's rotating black holes I described before.

578
01:11:45,350 --> 01:11:50,120
And so. We looked.

579
01:11:50,120 --> 01:11:56,540
Where there have no trainers correlated to detection to the directions of the blaze.

580
01:11:56,540 --> 01:12:04,030
And the answer was no. And so in desperation, in 2016.

581
01:12:04,030 --> 01:12:14,980
I challenge you to try any combination of astronomical sources with cosmic neutrinos that we didn't try out during those years.

582
01:12:14,980 --> 01:12:21,470
And so in desperation, where we started to do, I won't go through this slide, but.

583
01:12:21,470 --> 01:12:33,710
When we reconstructed the high energy neutrino, we actually just sent the data to the astronomical community in less than a minute.

584
01:12:33,710 --> 01:12:38,120
And this is frightening because you're sending your data to the world,

585
01:12:38,120 --> 01:12:43,040
and each time it happens, you get a message on your phone, there's nothing you can do.

586
01:12:43,040 --> 01:12:50,300
It's a strange feeling. And we did this the 10 times we did this.

587
01:12:50,300 --> 01:13:05,160
We send out this telegram on the 17th of September, the 22nd of September 19, 17, and it's 290, if not now.

588
01:13:05,160 --> 01:13:12,060
So probably cosmic that, oh, I have a picture of it.

589
01:13:12,060 --> 01:13:22,350
That came from the general direction of, in fact, the right shoulder of Orion, if someone can relate to that.

590
01:13:22,350 --> 01:13:33,480
This is the event and after a few days, the fact many people realise that in that direction we seem point zero six degrees.

591
01:13:33,480 --> 01:13:42,840
There was one of these place arcs and that place had increased its output by a factor of seven in the last few months.

592
01:13:42,840 --> 01:13:48,090
So we were somehow doing something. And.

593
01:13:48,090 --> 01:13:54,010
That as a probability of being an accident of one in a thousand.

594
01:13:54,010 --> 01:14:04,750
And as many of you know, these things happen all the time, not every day, but you know, it's interesting, but that's all it is.

595
01:14:04,750 --> 01:14:10,120
It's what happened afterwards that made this interesting.

596
01:14:10,120 --> 01:14:21,440
A gamma ray telescope in La Palma, Magic was looking at this object, and it discovered the TV gamma rays.

597
01:14:21,440 --> 01:14:29,860
We didn't know it then it was TV cameras, but given the distance of the souls, these are really very easy.

598
01:14:29,860 --> 01:14:36,830
I said it to detect the TV cameras, so that made it more interesting, more unusual.

599
01:14:36,830 --> 01:14:44,360
This is magic. It uses the atmosphere to detect gamma rays like we use eyes to detect neutrinos.

600
01:14:44,360 --> 01:14:51,860
By the way, we had no idea whether any astronomical telescope ever looked at our events.

601
01:14:51,860 --> 01:14:59,090
But here we got the answer. There were actually at some point twenty two telescopes pointing in this direction.

602
01:14:59,090 --> 01:15:05,330
Swift detected it first. Here is magic that is fair to me.

603
01:15:05,330 --> 01:15:08,420
And there you see all these other telescopes.

604
01:15:08,420 --> 01:15:17,270
What they were trying to do is detect the galaxy and detect the distance with the hope, which is very nearby.

605
01:15:17,270 --> 01:15:26,690
Galaxy will add to the evidence. Well, you have to wait because the galaxy was so bright you couldn't see the absorption lines.

606
01:15:26,690 --> 01:15:38,190
And after months, they detected this galaxy is four billion light years away, so 1.7 keycap.

607
01:15:38,190 --> 01:15:46,840
So. There are similar galaxies ten times closer that look the same to astronomers.

608
01:15:46,840 --> 01:15:52,870
And so we not only see our own galaxy, we don't see the nearby Gaia space.

609
01:15:52,870 --> 01:16:08,260
We see them far away. So the plot thickens, and so here is the good news, that's a story up to now summarise, but we keep all our data.

610
01:16:08,260 --> 01:16:13,890
We have all the hard data since the detective started operating on this.

611
01:16:13,890 --> 01:16:23,640
And so we can now you have an interesting direction, you can go and look in that direction in your whole data, nine and a half years of it.

612
01:16:23,640 --> 01:16:37,660
And here is the answer we. This is the beginning of the founding of the detector, and this, by the way, you're probably looking at the whole thing.

613
01:16:37,660 --> 01:16:42,160
This is what I've been talking about on the right hand side of the floor.

614
01:16:42,160 --> 01:16:53,590
It's one to three, you know, with a little bit of lower energy ones, but this is what we discovered in 2014.

615
01:16:53,590 --> 01:17:04,500
Not discovered far. And so this had produced 13 Latinos 19 on the background of less than six.

616
01:17:04,500 --> 01:17:09,430
In three months. No deal reset ever predicted such a thing.

617
01:17:09,430 --> 01:17:15,130
And so what happens is that you see, it's right on top of the source.

618
01:17:15,130 --> 01:17:21,490
We actually have enough events to measure the spectrum e to the minus 2.1.

619
01:17:21,490 --> 01:17:31,060
And as you use a prescription that published to look through data despite all the statistics you can discuss about this,

620
01:17:31,060 --> 01:17:36,040
the probability that this is a fluctuation is a few times 10 to the minus five.

621
01:17:36,040 --> 01:17:47,240
So this is a three or four, we get all the rest. And so this source, in case I hadn't mentioned it, yes, it's labelled excess of five of six.

622
01:17:47,240 --> 01:17:51,730
You heard that before. Here it is.

623
01:17:51,730 --> 01:18:01,650
So this burst makes this so stick out in a map that doesn't take time into account.

624
01:18:01,650 --> 01:18:10,350
So. That some guys will finally discover the cosmic Ray Accelerator.

625
01:18:10,350 --> 01:18:17,850
It's a blazer, allegedly, and so displays off was started by all these telescopes.

626
01:18:17,850 --> 01:18:22,860
So here you see the spectrum. It's an incredible spectrum.

627
01:18:22,860 --> 01:18:27,630
It's one of the best mass blazers now, but it also has.

628
01:18:27,630 --> 01:18:33,210
We know that there are no Tino's produced. And so I kind of enjoy this.

629
01:18:33,210 --> 01:18:40,800
This some of you, if you're old enough, this is Kabul at a time CP violation was discovered.

630
01:18:40,800 --> 01:18:54,810
And these are the theories of the weak interactions. In fact, when we discovered the famous neutrino theorist after trying to use blazer models,

631
01:18:54,810 --> 01:19:01,560
they were well known to how to produce the gamma rays, and they couldn't get one neutrino.

632
01:19:01,560 --> 01:19:09,930
And, well, they were telling me this. I knew it produced 13 retainers in three months, a few years before.

633
01:19:09,930 --> 01:19:17,640
And so that was the 2014 version blew up the theory of Blaze.

634
01:19:17,640 --> 01:19:24,860
So two possibilities everybody tried to do crazy modelling and.

635
01:19:24,860 --> 01:19:31,430
I'm proud of this reaction. Alec Hamdi's and I published a paper about this couldn't be a blaze of.

636
01:19:31,430 --> 01:19:40,060
And in fact, if they had paid attention, this jet had some with structure and this was known.

637
01:19:40,060 --> 01:19:45,160
And so what I want to remind you of, I mean, what's the big deal?

638
01:19:45,160 --> 01:19:51,280
Of course, it produced no trainers and no photons, whereas the first event produced one or three.

639
01:19:51,280 --> 01:20:02,250
No and a lot of photons. But so this accelerator at this time, the accelerator was like sound where you get neutrinos and no gamma rays and the beam.

640
01:20:02,250 --> 01:20:14,520
And so here were our observations. First of all, if every place our family sees produces this once in 10 years, this stuff to knows.

641
01:20:14,520 --> 01:20:24,090
And all the Blazers did this, we would overproduce of diffuse flux, which we know and love by a factor of 20.

642
01:20:24,090 --> 01:20:35,390
So it had to be a special sauce. The other thing is that if anything, produces 30 neutrinos in three months, its target is like the sound talk.

643
01:20:35,390 --> 01:20:43,550
It's like a block of steel, you know, not quiet, but the time of the photons don't get out, which is consistent with the data.

644
01:20:43,550 --> 01:20:49,040
In fact, a few photons can get out, which we can understand.

645
01:20:49,040 --> 01:20:58,120
So the conclusion was. So this is like a blazer, it's a jet, it's a rotating black hole.

646
01:20:58,120 --> 01:21:04,250
But there must be something throwing a target into.

647
01:21:04,250 --> 01:21:16,620
The blaze are and of course, it was subsequently discovered that this galaxy to excess is merging with another galaxy.

648
01:21:16,620 --> 01:21:25,960
And so now the problem is solved. Either the two jets can untangle and you get more light to interact with,

649
01:21:25,960 --> 01:21:36,640
or more likely the jets interact with the accretion disk of matter that fills up between the two black holes that marching.

650
01:21:36,640 --> 01:21:44,970
So the problem from unexploded, you know, unsolvable becomes trivial.

651
01:21:44,970 --> 01:21:54,630
People have pointed out that if you look at radio data, this event actually came on the point on the peak in the radio data.

652
01:21:54,630 --> 01:22:01,740
Suddenly, the radio telescopes came in the day and this is interesting because the highest energy alert we

653
01:22:01,740 --> 01:22:12,150
ever got is a 380 v neutrino that came during the Cosmic Ray conference in Madison last summer.

654
01:22:12,150 --> 01:22:18,240
And in fact, if you look at the radar, it points at a so-called blaze off.

655
01:22:18,240 --> 01:22:24,430
At the peak. Of radio bursts, probably in March or again.

656
01:22:24,430 --> 01:22:39,430
And in fact, Alma discovered that the highest source in our map at the moment this this galaxy, NGC Typekit 68, is also merging with something.

657
01:22:39,430 --> 01:22:42,700
And producing neutrinos because of it.

658
01:22:42,700 --> 01:22:54,160
I'm going to finish by telling you, not telling you about the fact that, of course, we are working very hard to combine our data with Sligo.

659
01:22:54,160 --> 01:22:58,840
We have been doing this since before the discovery of black hole mergers.

660
01:22:58,840 --> 01:23:01,870
And so we continue to do this.

661
01:23:01,870 --> 01:23:12,640
I could give you a long lecture, and the conclusion would be that we maybe can see neutrinos from neutron star mergers now,

662
01:23:12,640 --> 01:23:20,230
but will certainly do it with the next generation experiment. So let me conclude, and that's easy.

663
01:23:20,230 --> 01:23:27,280
The important thing of to love from the star is that three Nostromo may exist.

664
01:23:27,280 --> 01:23:38,170
We have the methods to do it, but when you follow this stock, it's clear we don't have enough events and we have only one telescope.

665
01:23:38,170 --> 01:23:44,860
And you cannot do astronomy that way. We need better angular resolution with bigger detectors.

666
01:23:44,860 --> 01:23:51,410
We are starting the process of building a detector that's 10 times IceCube.

667
01:23:51,410 --> 01:23:58,640
And there is a detector being built in Lake Baikal that this prison.

668
01:23:58,640 --> 01:24:05,480
If everything goes well, we will reach a size where they can see the diffuse flux I have been talking about.

669
01:24:05,480 --> 01:24:10,740
And there is a detective being developed in the Mediterranean to empty net.

670
01:24:10,740 --> 01:24:23,330
He just deployed its structure on the bottom of the ocean, which will reach eventually ice size and eventually larger detector.

671
01:24:23,330 --> 01:24:30,681
Thank you for your attention.