1 00:00:01,480 --> 00:00:15,310 So. Pleasure to be here. 2 00:00:15,820 --> 00:00:23,560 Uh, just in time. Delivery? Absolutely. Um, all my complex travel plans for this week almost completely unravelled. 3 00:00:23,770 --> 00:00:28,150 It's not micron's not working for that now. 4 00:00:28,270 --> 00:00:33,970 All my travel plans can be almost completely unravelled today. And today was the simple day I've come in from South Africa. 5 00:00:34,000 --> 00:00:37,150 London, uh, Stock Council. 6 00:00:37,540 --> 00:00:40,719 So. Yes. Anyway. But I'm glad to be here. Glad I could make it. Um, yes. 7 00:00:40,720 --> 00:00:45,880 I'm going to talk a bit about protocols, because this is very much a personal story, personal reflections of, uh, 8 00:00:46,360 --> 00:00:56,110 actually how I saw the field grow with Dom's leadership, um, through, uh, proton decay, but actually how that then connected to neutrino oscillations. 9 00:00:56,530 --> 00:01:01,270 Now, I'm not going to talk about the physics results of neutrino oscillations because we have a presentation after this. 10 00:01:01,750 --> 00:01:06,850 This this great picture here is the Sudan one. Uh, detector in its full glory. 11 00:01:07,240 --> 00:01:11,740 Didn't run for very long. You probably see why. Um, but you can see these three gentlemen here. 12 00:01:11,740 --> 00:01:14,740 So in front, it's Tom fields from Argonne National Laboratory. 13 00:01:15,130 --> 00:01:18,880 Melvin Marshak from, uh, University of Minnesota in the back. 14 00:01:18,880 --> 00:01:25,420 A very suspicious looking gentleman inspecting the hardware and not looking very happy, actually, in that picture. 15 00:01:25,840 --> 00:01:29,890 Um, but that really was the start of, uh, start of that journey. 16 00:01:30,160 --> 00:01:34,450 So, so this is very much personal reflection. Um, I'm not going to go too deeply into the science. 17 00:01:34,600 --> 00:01:40,899 Most people in here another science, but I that I what I want to do is put this in a historical perspective of how 18 00:01:40,900 --> 00:01:45,910 the search for proton decay actually shaped much of neutrino physics today. 19 00:01:46,030 --> 00:01:49,660 And of course, Don was a leading figure in this area. 20 00:01:49,930 --> 00:01:53,530 Actually, one of the pleasures of this putting this presentation together. 21 00:01:54,070 --> 00:02:01,209 Just in time. Delivery 4:00 in this this morning. Um, was actually reading, although I read some of the papers, uh, 22 00:02:01,210 --> 00:02:06,370 last night was actually reading some of the earlier papers, papers I hadn't picked up for 40 years. 23 00:02:06,370 --> 00:02:10,090 And it was, uh, quite, quite fascinating. So why am I here? 24 00:02:10,180 --> 00:02:14,499 Uh, the first answer's obvious. Proton lifetime is longer than the lifetime of the universe. 25 00:02:14,500 --> 00:02:19,090 That is actually quite is actually quite useful. Um, so it's a useful property. 26 00:02:19,750 --> 00:02:25,720 That's not really what I meant. Um, I started my DPhil here back in 1995. 27 00:02:25,750 --> 00:02:32,140 Uh, experimental particle physics at Oxford. And I decided to work on a proton decay experiment in Minnesota. 28 00:02:32,560 --> 00:02:41,350 Underground and very cold. This is a picture, uh, I think Mark Lancaster dagger dug out from the Royal Summer school, but, yeah, um, 29 00:02:41,350 --> 00:02:47,590 I don't know if there were any other people I saw I should have taken is quite I don't look, I will get, like, get rid of that very quickly. 30 00:02:47,950 --> 00:02:54,700 Um, but we did actually try we did try to identify a few years ago to try to identify all of the faces and figure out where they were. 31 00:02:54,700 --> 00:02:59,650 And there are about five we didn't get, but, um, so, so so why did I go on to ground? 32 00:02:59,920 --> 00:03:04,270 Um, so going back to the Don's point, what was the attraction with Sudan too? 33 00:03:04,420 --> 00:03:13,389 Um, for me it was a small collaboration. Um, it was it felt much more hands on the technology, the electronics. 34 00:03:13,390 --> 00:03:18,219 And actually we had a really, really great team at Oxford and just the focus. 35 00:03:18,220 --> 00:03:25,690 And so the that page is a page from my thesis that someone dug, kindly dug out for me from the library at Oxford. 36 00:03:26,170 --> 00:03:29,409 But that's, that's the collaboration. So it was a small collaboration. 37 00:03:29,410 --> 00:03:32,800 And the group, um, the group at Oxford was also relatively small. 38 00:03:33,250 --> 00:03:40,629 Uh, Don, obviously, I absolutely think, uh, John Cope and Charles Ball, um, are both both on that, that collaboration. 39 00:03:40,630 --> 00:03:42,730 So it was a really nice small group, very tight knit group. 40 00:03:42,730 --> 00:03:47,950 And it was uh, that was part of the attraction, but actually it was part of the science, part of the science. 41 00:03:47,950 --> 00:03:55,300 And ultimately the science was this was us astro particle physics or particle astrophysics, depending where you come from. 42 00:03:55,780 --> 00:04:01,149 Before it was really a big thing. So it was a really interesting time to get involved in this, this area. 43 00:04:01,150 --> 00:04:05,950 You saw the field growing, uh, and gradually growing into what it is today. 44 00:04:07,140 --> 00:04:11,310 So proton decay in 1984 was a seriously hot topic. 45 00:04:11,580 --> 00:04:16,380 Um, this paper, which is this this was the paper I was reading actually last night. 46 00:04:16,410 --> 00:04:23,220 Um, proton decay experiments. It was in the annual review of, uh, nuclear and particle, uh, science. 47 00:04:23,490 --> 00:04:32,550 So it was obviously written by Don. It was really a very, very deep overview of the field, the theory, the experimental status back in 19 1984. 48 00:04:33,820 --> 00:04:37,210 Um, I also I tried to remember what 1984 was like. 49 00:04:38,380 --> 00:04:41,920 Um, I looked, I said, I typed in what was hot in 1984. 50 00:04:41,920 --> 00:04:46,030 That wasn't a good idea. Um, but then I looked at some more specific searches. 51 00:04:46,690 --> 00:04:55,910 I actually remembered what else was hot. The. So this this was music in 1984, and I'm sure we all agree much better the music today. 52 00:04:55,930 --> 00:05:00,490 I think. I think I think we're all of a sufficient generation that that is probably true. 53 00:05:00,940 --> 00:05:07,240 But actually, again, it really, really took me back to, um, what it was like to be an Oxford, um, during, during those times. 54 00:05:08,080 --> 00:05:12,260 So why actually, I mean, this is more, more why proton decay was the hot topic. 55 00:05:12,280 --> 00:05:17,889 So if you look back to, uh, a long time ago, discovery of W and Z, um, 56 00:05:17,890 --> 00:05:22,150 firmly established the gauge theory of the Standard Model, the electroweak sector of the standard. 57 00:05:22,150 --> 00:05:32,260 Standard model. So that's a big tick. Um, as the late 70s, early 80s, the C3 gauge theory of QCD had also been kind of confirmed by experiments. 58 00:05:33,360 --> 00:05:38,230 Um, and experimental data at the time. This this is not the data from the time. 59 00:05:38,250 --> 00:05:45,090 Uh, this is the tidier plot. This suggested that the three main forces, the strengths of the three main forces, converged at a scale. 60 00:05:45,540 --> 00:05:49,920 Um, at that time, from Dan's paper, it was ten to the 14 GV. 61 00:05:50,310 --> 00:05:56,940 Of course, you can change the bottles around you. You get slightly different answer. Um, so there was there was a hint of grand, grand unification. 62 00:05:57,720 --> 00:06:04,090 Uh, and then Georgie and Glashow actually brought these ideas together in the context of an Su five grand unified theory. 63 00:06:04,110 --> 00:06:12,600 So you put the quarks and leptons in the same mode structure, and you end up with a new force at the scale of unification, 64 00:06:12,750 --> 00:06:16,920 mediated by the imaginatively named at the time, X and Y bosons. 65 00:06:17,430 --> 00:06:24,490 Very, very, very heavy though. Um, so obviously a consequence of this new theory was baryon number is not conserved. 66 00:06:24,510 --> 00:06:31,209 If you have this theory and the proton should decay. But again, I think in Don's article, actually, it was really, 67 00:06:31,210 --> 00:06:35,680 really interesting just just to make that connection because we kind of know that baryon 68 00:06:35,680 --> 00:06:40,360 number non conservation is out there because where does matter left in the universe. 69 00:06:40,360 --> 00:06:48,580 And it is one of the three conditions Sakharov conditions necessary to actually have matter left leftover in the universe from the Big Bang. 70 00:06:49,060 --> 00:06:57,040 So this is a really nice convergence of experimental data hinting at unification, uh, and connecting to, uh, deeper, deeper symmetries. 71 00:06:57,760 --> 00:07:04,270 So that's why it was, I think, a really hot topic. Um, what I going I like these old diagrams. 72 00:07:04,270 --> 00:07:07,479 These aren't made with, um, LaTeX packages, as you can tell. 73 00:07:07,480 --> 00:07:10,690 These these look like they were hand hand drawn. Um. 74 00:07:10,690 --> 00:07:15,440 So simple. Qe5 grand unified theory. This is the underlying proton decay process. 75 00:07:15,440 --> 00:07:21,220 It's not the only one. There are others. Um, you can always draw Higgs bosons in there, whatever you want. 76 00:07:21,850 --> 00:07:28,540 Um, but basically, it's the process, um, goes to X producing a charged lepton and an antiquark. 77 00:07:28,960 --> 00:07:31,830 And, uh, you can see the final states here. 78 00:07:31,840 --> 00:07:39,880 You'll end up with the antiquark combining with the quark, and you end up with a charged lepton and a neutral meson. 79 00:07:40,100 --> 00:07:44,319 It doesn't have to be. The pi can be others. Um, of course, the pi zero will then decay. 80 00:07:44,320 --> 00:07:48,130 So that's one final state. Uh, there are other models. 81 00:07:48,310 --> 00:07:52,450 Um, the they were available and they still are available. So if you become supersymmetric. 82 00:07:52,520 --> 00:07:59,920 Uh, if that's that's that's the way you wish to go. They tend to projects, um, the final state, lepton to be a neutrino. 83 00:08:00,190 --> 00:08:03,490 Uh, typically, uh, an anti town neutrino. 84 00:08:04,090 --> 00:08:09,760 So one of the flavour Italian notes that I was p to k plus, uh, anti-terror neutrino. 85 00:08:10,680 --> 00:08:13,930 Now, you can immediately say that these two topologies are very, very different. 86 00:08:13,960 --> 00:08:20,290 One is very, very light relativistic particles, uh, which, which interact electromagnetically. 87 00:08:20,740 --> 00:08:25,270 And the other decay is a single, um, hydraulically interacting particle that will decay. 88 00:08:25,750 --> 00:08:30,670 So the signatures are very, very different. Well, it does work. 89 00:08:31,450 --> 00:08:36,339 You can then start to actually just take the Grand Unified theory and actually start to use 90 00:08:36,340 --> 00:08:42,010 simple dimensional arguments to try and figure out what the lifetime of the proton is should be. 91 00:08:42,880 --> 00:08:47,530 Um, so this, this, this is quite a very simplified sort of the only equation in here actually. 92 00:08:47,950 --> 00:08:53,769 So you've got the very, very heavy dosage goes on to the, uh, the power force. 93 00:08:53,770 --> 00:09:01,929 So that's just the propagator term. You've got the strength of the grand unified coupling on the top and the ISO on the bottom. 94 00:09:01,930 --> 00:09:06,399 And, and at the bottom, you've also got the, the mass of the proton to the fifth power. 95 00:09:06,400 --> 00:09:14,110 So that's just phase space. And then you've got the, the, the the usual kind of fudge factor a which will take to be of order one. 96 00:09:14,680 --> 00:09:17,200 You put the numbers in and you get out uh, 97 00:09:17,200 --> 00:09:25,510 that the proton lifetime should be typically something like or at least uh sorry I it should be greater than or equal to ten to the 31 years. 98 00:09:25,960 --> 00:09:31,630 So out of this theory you get a very, very long proton lifetimes, which again is consistent with with observation. 99 00:09:32,930 --> 00:09:36,680 Um, now the experimental challenge. And it is a real experimental challenge. 100 00:09:36,710 --> 00:09:39,680 You're looking for signatures which are quite low energies. 101 00:09:39,860 --> 00:09:46,970 There's obviously the energy scales that the proton has, and you're looking for proton decay with lifetimes of ten to the 31. 102 00:09:47,930 --> 00:09:54,530 Um, the easy thing to do, if you could do it, would just be watch one proton IP, a nice signature so you could see it decay. 103 00:09:54,800 --> 00:09:58,220 Not very practical and actually not very interesting at all. 104 00:09:59,030 --> 00:10:04,010 Or you can take roughly ten to the 31 protons and watch them for a few years. 105 00:10:04,280 --> 00:10:10,610 Um, and the challenge then is actually getting together ten to the 31 protons or more, 106 00:10:11,450 --> 00:10:16,700 quite large volume, and actually seeing a single decay, a fairly low energy decay in that huge volume. 107 00:10:16,710 --> 00:10:21,380 That's the experimental challenge. So you're going to look at maybe a thousand ton detector. 108 00:10:21,800 --> 00:10:25,820 Within that detector, one of those protons goes pop. You want to see it. 109 00:10:26,210 --> 00:10:32,870 Um, so very very challenging. So two distinct signatures drove two different approaches. 110 00:10:32,870 --> 00:10:44,000 So the electromagnetic proof approach gives you uh, sorry the, the uh, C5 um, the k a pi zero where the pi zero then decays to photons. 111 00:10:44,300 --> 00:10:48,110 You have relativistic electromagnetically interacting particles. 112 00:10:48,740 --> 00:10:51,800 And in the other case you have a slow kaon which then decays. 113 00:10:52,960 --> 00:10:57,520 So there were two experiments approaches basically based on those two signatures. 114 00:10:58,150 --> 00:11:04,840 So a really good way to be able to actually take a very large volume of material and, um, 115 00:11:04,840 --> 00:11:14,140 see a signature of a single decay is just used to use water and look at the Cherenkov radiation, as we now do in the very large neutrino experiments. 116 00:11:14,950 --> 00:11:18,520 So this was pursued by the Emby detector in the US. 117 00:11:19,150 --> 00:11:26,830 This is a this is a diagram actually from one of the papers. I think it shows perhaps progress in our representation of our detectors. 118 00:11:27,910 --> 00:11:34,140 Those dots are photomultiplier tubes. If Don was here today, he would be actually horrified. 119 00:11:34,160 --> 00:11:35,980 So I did find a mistake in his paper. 120 00:11:36,860 --> 00:11:46,599 I wasn't I am, he wrote not I am B it was IBM and I wouldn't he wouldn't have lied anyway, that's uh um so this this a detector in the US. 121 00:11:46,600 --> 00:11:50,440 And of course, then there was the Kashmir nuclear on to k experiments in Japan. 122 00:11:50,740 --> 00:11:55,420 So now known as Kashmir can go but the NDE is nuclear on decay experiment. 123 00:11:55,420 --> 00:11:59,700 That's what it was designed for. Um, they're also tracking calorie misses. 124 00:11:59,970 --> 00:12:06,480 So these, these these were typically, uh, mixes of steel, steel planes, drift tubes. 125 00:12:06,960 --> 00:12:10,710 Protons sit in the steel when they decay, they cross the drift tubes and you see a signature. 126 00:12:10,720 --> 00:12:14,650 I'll. I'll talk about Sudan, too, in a minute. Um. 127 00:12:15,700 --> 00:12:18,160 So that's that. That was the experimental approach. 128 00:12:18,310 --> 00:12:25,120 The challenge you're looking for a single proton decay or just a handful if you want to make that discovery very, very big detector. 129 00:12:25,600 --> 00:12:30,230 Um, this is an I like this diagram because it was quite, quite dated. 130 00:12:30,250 --> 00:12:36,810 Um, there's a plane flying there. Um, so anyway, you're looking at a very, very large detector. 131 00:12:36,820 --> 00:12:39,260 So cosmic ray induced background is a problem. 132 00:12:39,280 --> 00:12:45,880 So if you have neutron lots of neutrons flying around from spallation, they can fake a signal so they can bump into something in your your detector. 133 00:12:46,240 --> 00:12:50,590 And you'll get a signature that could fight. It's like, um, a proton decay. 134 00:12:51,400 --> 00:12:57,490 So you when you go deep underground and that's fine. Um, but you're always left with atmospheric neutrinos. 135 00:12:57,490 --> 00:13:01,260 You can't get away from the atmospheric neutrinos. So what? 136 00:13:01,770 --> 00:13:05,730 I think these proton vehicle experiments actually changed particle physics. 137 00:13:06,060 --> 00:13:10,950 Firstly, they were large underground experiments and so on, really very large at the time. 138 00:13:11,700 --> 00:13:19,550 And they were sensitive to the otherwise not very interesting neutrino induced backgrounds, but not very interesting at the time perhaps. 139 00:13:20,130 --> 00:13:21,920 Now we know that's not the case. 140 00:13:21,930 --> 00:13:29,280 So these experiments I think really did change the change, change the way we've been doing physics over the last years. 141 00:13:30,910 --> 00:13:33,970 I made a mistake in the slides, which I spotted ten minutes ago. 142 00:13:34,010 --> 00:13:37,800 Um, just stepping forward a few years. I just got this quote. 143 00:13:37,810 --> 00:13:41,290 It's just a quote from a conference paper. I thought it was really interesting just because it. 144 00:13:42,200 --> 00:13:48,260 Links to one of the messages I want to get out at the end. Um, so this is the situation in 1986. 145 00:13:48,530 --> 00:13:58,490 Um, five experiments cola use the phrase you, I am B and Tamiya candy designs discover nucleon decay all around the world about Northern hemisphere. 146 00:13:59,180 --> 00:14:07,759 One experiment is being constructed Sudan. Two and two others are under serious discussions super cameo candy and ultimately obviously a very, 147 00:14:07,760 --> 00:14:11,680 very important experiment in neutrino physics and proton decay, actually. 148 00:14:12,290 --> 00:14:17,170 And Icarus. And obviously just noting nucleon decay had not been discovered at that time. 149 00:14:17,890 --> 00:14:22,030 Um, but I think it's very interesting that these are familiar techniques, 150 00:14:22,030 --> 00:14:25,570 the red ones, apart from Supercam, you can see which is actually made from water. 151 00:14:26,030 --> 00:14:32,680 Um, the red ones are tracking channel images. They evolved to the Minos experiment, which I'll talk talk about. 152 00:14:33,550 --> 00:14:38,320 Uh, the water Cherenkov detectors. Um, supercam you can do that is now. 153 00:14:38,710 --> 00:14:42,760 Sorry. How many times evolved and supercam your fancy. And now, of course, hypothermia can die. 154 00:14:43,660 --> 00:14:49,780 And then you make a new one. On the block was Icarus, which was a the first liquid large scale liquid argon TPC. 155 00:14:50,500 --> 00:14:57,340 And of course, that's had a longer gestation period, but that's now evolving into the dune deep underground neutrino uh experiment technology. 156 00:14:57,670 --> 00:15:06,790 So you can even even back in 1986, you see, you can see, um, the foresight of what what might come in the future. 157 00:15:08,070 --> 00:15:12,040 Right. He was about to Sudan to my DPhil thesis. 158 00:15:12,040 --> 00:15:15,390 So I was kind of put this is quite a personal reflection. 159 00:15:16,050 --> 00:15:19,590 Deepest, darkest Minnesota and not really his deepest, darkest Minnesota. 160 00:15:19,590 --> 00:15:24,450 The largest. The nearest large town Ely, Minnesota, not Ely, Cambridgeshire. 161 00:15:25,050 --> 00:15:30,930 Um, it was really interesting when I was choosing projects, I had these these were the main options that were on offer. 162 00:15:31,140 --> 00:15:35,969 Others were on offer as well there at Daisy, that had lots of advantages. 163 00:15:35,970 --> 00:15:41,880 And I can see many, uh, Zeiss, um, uh, colleagues here, Hamburg nightlife being one of them. 164 00:15:42,090 --> 00:15:49,499 I certainly I think the students who went there and enjoyed that selfie at CERN on the large electron positron collider, mountains and skiing. 165 00:15:49,500 --> 00:15:53,790 I actually put that off for a few years, but it got there in the end. And then Sudan, too. 166 00:15:53,790 --> 00:15:57,810 In Minnesota, lots of snow, no skiing, no mountains. 167 00:15:58,500 --> 00:16:02,160 Uh, I finally remember what it was three two there. 168 00:16:02,730 --> 00:16:07,200 So this is basically low alcohol. Beer was all you could get in the state of Minnesota at the time. 169 00:16:08,100 --> 00:16:12,270 Um, but actually a really great an interesting group of excite scientists. 170 00:16:12,270 --> 00:16:14,849 And that's obviously the attraction, including Don and that, um, 171 00:16:14,850 --> 00:16:18,989 I just saw Rogers looking at me that it's not saying that there weren't great and interesting sciences. 172 00:16:18,990 --> 00:16:22,049 And the other experiments, of course, there were, um, but there were. 173 00:16:22,050 --> 00:16:25,830 But but but it was, as I say earlier, as part of the part of the attraction. 174 00:16:25,830 --> 00:16:30,560 So that's why I did it. I think by modern day standards. 175 00:16:30,570 --> 00:16:34,560 You look at the picture, this is a very blurry photograph of the detector. 176 00:16:34,740 --> 00:16:37,830 This was during the the installation construction period. 177 00:16:38,430 --> 00:16:45,090 Um, it doesn't look super high tech. Um, but it did actually work incredibly, incredibly well. 178 00:16:45,690 --> 00:16:50,930 Um, the it's a half a half mile underground. Um, you would go down the mine carriage. 179 00:16:50,940 --> 00:16:54,300 So many of us go down, lots of have been done. Lots of different line stages. 180 00:16:54,810 --> 00:16:59,100 I think this is one of the more fun ones. No lights. Lots of bats flying around your head. 181 00:16:59,520 --> 00:17:04,770 Uh, the rust up from the, uh, cabins on the ground. So it was always an always an interesting experience getting down. 182 00:17:05,370 --> 00:17:09,280 Um. So how does it actually work? Um. 183 00:17:10,530 --> 00:17:16,530 So. Yeah. So this parchments picture I took, I took a photograph of, um, the basic detector. 184 00:17:16,530 --> 00:17:22,890 And it was really, really quite simple. It's just a cheap 1.5cm, um, diameter resistive tube. 185 00:17:23,070 --> 00:17:27,000 Put some the put an electric field around it. So what happens? 186 00:17:27,360 --> 00:17:30,690 Um, one of my points of no, I won't try and point up there. 187 00:17:31,170 --> 00:17:35,760 Um, particle cross crosses that region ionises the gas, the gas. 188 00:17:35,760 --> 00:17:41,530 Then the ions drift along the the field lines and you get signatures on the, uh, 189 00:17:41,610 --> 00:17:46,170 wires at the end, the anodes, and you've got an induced signal on the cathode planes. 190 00:17:46,890 --> 00:17:50,460 So every time a particle goes through one of these tubes, you get a electronics blip. 191 00:17:51,570 --> 00:17:57,330 And then what? What you do is you sandwich all those tubes into a corrugated honeycomb structure. 192 00:17:57,880 --> 00:18:02,580 Uh, this is a picture. If even looking at that picture, you can. This must have been a bad module or something. 193 00:18:02,580 --> 00:18:07,640 It doesn't look very well aligned, actually. Um, but of course, it's the steel that provides all the protons. 194 00:18:07,650 --> 00:18:13,590 So if one of those protons in that steel decays, particles will come out across the gas and you'll get signatures. 195 00:18:14,280 --> 00:18:18,000 So very actually a very simple, very simple principle. Very effective. 196 00:18:19,190 --> 00:18:27,500 Um, so actually what you what you end up doing is you build it, put these tubes in modules, and I think there were, uh, 256. 197 00:18:27,530 --> 00:18:32,270 Yes, about 256 of them making up about a kiloton of of mass. 198 00:18:33,610 --> 00:18:36,220 And that's the detector. And it's full, full glory. 199 00:18:36,340 --> 00:18:42,730 Um, uh, clearly not taken with a modern, modern, modern camera, but so pretty, pretty simple technique. 200 00:18:43,180 --> 00:18:47,390 But you have to have some simple techniques because you need very large, massive detectors. 201 00:18:47,400 --> 00:18:55,000 So simplicity actually is is is a real benefit. So Sudan two was designed to study proton decay. 202 00:18:55,020 --> 00:19:01,200 That's why it was built. Designed. Um, in some ways, it's actually a really beautiful detector. 203 00:19:01,230 --> 00:19:08,790 It's a very large volume. And you have voxels, um, like pixels, but three dimensional pixels, roughly a cubic centimetre. 204 00:19:08,790 --> 00:19:13,890 So that's your resolution, uh, for particles. You have very low thresholds, gas detection. 205 00:19:14,520 --> 00:19:18,590 And because you're ionising the gas, you actually get good particle particle I.D. as well. 206 00:19:18,600 --> 00:19:21,690 And you could then make free projected 3D images. 207 00:19:22,440 --> 00:19:26,970 So these were the some of the an example of some of the event displays. 208 00:19:27,000 --> 00:19:30,690 Um, just to give you a sense of what the events in this detector look like. 209 00:19:30,720 --> 00:19:36,930 So you did you got the tracks, measured the tracks, or what happened to them as they scattered in the, in the medium. 210 00:19:38,650 --> 00:19:44,710 Um, what about the results? Well, I think everybody knows proton decay hasn't been discovered yet, so. 211 00:19:44,740 --> 00:19:47,800 So you then two did not discover proton decay? Many, many. 212 00:19:48,010 --> 00:19:52,720 I mean, one of the advantages of this is you could look at many, many different k typologies because you saw the topology. 213 00:19:52,930 --> 00:19:58,300 Um, all of the channels had some level of expected neutrino, um, background. 214 00:19:58,570 --> 00:20:04,510 Um. And I mean Giles. Giles, who's just sitting, actually just sitting, sitting in front of where I sat down earlier, 215 00:20:04,550 --> 00:20:08,110 he, you know, he was working on these analyses for, for a number of years. 216 00:20:08,110 --> 00:20:11,560 And, you know, neutrino backgrounds were absolutely key. 217 00:20:11,650 --> 00:20:14,830 And fruit Giles, the Oxford group actually played a long, 218 00:20:15,280 --> 00:20:22,720 very significant role in actually tuning the simulations about historic neutrinos and and cosmic rays, showers and production of neutrinos. 219 00:20:23,500 --> 00:20:27,460 The bottom line was what was seen in the experiment was consistent with these backgrounds. 220 00:20:27,700 --> 00:20:35,530 Um, so the most stringent time life time limit from, um, Sudan two was a very long time, six times ten to the 32 years. 221 00:20:36,280 --> 00:20:39,700 Um, but if you look at, look at the if you also then compare that. 222 00:20:39,700 --> 00:20:45,580 So that is actually a pretty impressive result. Today's best limits come from the Supercam Joachim's experiments. 223 00:20:45,640 --> 00:20:51,370 Um, water is very scalable. You can. As long as you like to propagate through that water, you can. 224 00:20:51,490 --> 00:20:54,550 And you have enough money to pay for the nose pliers. 225 00:20:54,610 --> 00:20:59,290 Um, you can scale it. So very, very large detector, very large foundational mass. 226 00:20:59,920 --> 00:21:05,260 And now the current lifetime limits are up at 1010 to the 34th, ten to the 34 years. 227 00:21:06,700 --> 00:21:09,580 So the proton decay. So the legacy, um. 228 00:21:10,710 --> 00:21:18,240 One of the things I really enjoyed about being in Oxford, um, back in the late 80s, was actually discussions over coffee. 229 00:21:18,250 --> 00:21:23,910 There was a very active culture of meeting up with colleagues and, uh, over coffee, not talking about football. 230 00:21:24,060 --> 00:21:26,730 Um, actually talking talking about physics. 231 00:21:26,740 --> 00:21:35,010 Um, so obviously myself and John who I saw up there, John Perkins, sometimes got, um, livened up by Mike Fowler chipping in. 232 00:21:35,640 --> 00:21:41,230 Uh, some of the discussions certainly with John looked a bit like that. Um, but I was hoping Joe was going to be here today. 233 00:21:41,260 --> 00:21:45,420 Uh, um uh, but actually the discussions were great, and it was really physics. 234 00:21:45,430 --> 00:21:50,159 We talked about proton decay. Obviously, Don had his passion for cosmic ray physics. 235 00:21:50,160 --> 00:21:56,640 So we actually talked about cosmic ray physics. My my thesis was actually more connected to cosmic ray physics and proton decay. 236 00:21:57,330 --> 00:22:02,160 But actually we started talking more and more about neutrinos and neutrino oscillations. 237 00:22:02,640 --> 00:22:07,800 Um, uh, and really because at this time the solar neutrino puzzle was out there, 238 00:22:08,070 --> 00:22:13,350 but actually also these proton decay experiments were sort of starting to see anomalies, not all of them. 239 00:22:13,800 --> 00:22:20,340 Some of them saw things that were consistent with the standard normal oscillating predictions, but others were showing hints. 240 00:22:21,030 --> 00:22:26,830 So we were starting to see hints that the background of proton decay was was actually the signal for something else. 241 00:22:26,910 --> 00:22:30,600 Uh, something else we now know is extremely, extremely interesting. 242 00:22:32,540 --> 00:22:37,549 So what I think and I will actually I'm going to because I'm going to argue this. 243 00:22:37,550 --> 00:22:38,840 I think you could argue that. 244 00:22:38,840 --> 00:22:48,620 So Sudan to um, ceded what is now a very, very strong, um, UK neutrino activity with Fermilab in parallel with a very strong collaboration with, 245 00:22:48,620 --> 00:22:52,370 with with Japan, the members of the Sudan two collaboration. 246 00:22:52,370 --> 00:22:57,290 They were actually key in the development for the concept of P8 seven five. 247 00:22:57,290 --> 00:23:03,350 I hope I've got the number right. Uh, a long baseline neutrino oscillation experiments at at Fermilab. 248 00:23:04,460 --> 00:23:08,570 And this ultimately resulted in the formation of the Minos collaboration. 249 00:23:08,630 --> 00:23:10,640 Um, I think that was helped. 250 00:23:10,940 --> 00:23:19,440 I'm not sure that's the right word, but the demise of the SCC in 1993, which, uh, actually really made, made the collaboration very strong. 251 00:23:19,470 --> 00:23:24,200 So, Stan, that was one of the leading figures in the development of the proposal and the experiments. 252 00:23:25,340 --> 00:23:29,830 It also turns out that if you start at Fermilab. Sudan. 253 00:23:29,860 --> 00:23:35,649 The Sudan mine is about 730 miles away. That turns out to be just about the right distance. 254 00:23:35,650 --> 00:23:40,420 Not perfect, but to study neutrino oscillation oscillations from you on neutrinos. 255 00:23:41,230 --> 00:23:45,670 Um, you've got to go underground again. So you go back to the Sudan mine. 256 00:23:46,390 --> 00:23:51,160 Um, so this was a second generation long time neutrino oscillation experiment. 257 00:23:51,220 --> 00:23:59,620 Uh, I'm not going to go into the details here in great detail, but the basic idea is you go to Fermilab, you've got a nice accelerator complex. 258 00:23:59,620 --> 00:24:03,100 You smash 120 GeV protons into a target. 259 00:24:03,640 --> 00:24:07,959 Uh, three create a beam of neutrinos. They fly across. 260 00:24:07,960 --> 00:24:13,390 Well, actually, under, um, under the Midwest, under, um, uh, Lake Superior. 261 00:24:14,020 --> 00:24:17,050 And then you detect those neutrinos with big detectors. 262 00:24:17,200 --> 00:24:22,810 Uh, one of them you put right near the source, and then one of them you put down the mine. 263 00:24:23,440 --> 00:24:28,660 So that's the basic experiment. And then you compare what you see close to the to the source and a long way away. 264 00:24:29,080 --> 00:24:32,530 And if they're different, something's happened to the neutrinos they've oscillated. 265 00:24:33,500 --> 00:24:36,510 I think. I think Paul will say more about that in his his presentation. 266 00:24:37,020 --> 00:24:39,570 Again, these detectors were actually fairly simple. 267 00:24:40,290 --> 00:24:49,540 Um, uh, if you compare these to the, the pretty well, the LHC or even the um, large electron positron collided sectors, these are pretty simple. 268 00:24:49,590 --> 00:24:54,360 The simple, because the thing you're aiming for is mass. You need to get a lot of mass in your detector. 269 00:24:55,200 --> 00:25:02,250 Um, so this is this is the detector. Basically, it's planes of steel and, uh, interlaced with scintillator. 270 00:25:02,280 --> 00:25:08,100 So 484 one inch thick steel planes with one centimetre scintillator in between. 271 00:25:08,850 --> 00:25:12,090 Somewhat similar to the Sudan idea. All of your protons. 272 00:25:12,390 --> 00:25:17,460 What most if instead still if something decays, it will cross some scintillator, 273 00:25:17,940 --> 00:25:23,110 give a flash of scintillation scintillation light, and then you read it out so you get a signal. 274 00:25:23,160 --> 00:25:26,880 Um, in this case in MTC. So lots of layers. 275 00:25:27,180 --> 00:25:30,959 Just to give you a sense, the that's not that that's a bit of plastic at the bottom. 276 00:25:30,960 --> 00:25:36,060 That is the basic detector. It's detecting elements. And then you have to put a bunch of TMT on the end of it. 277 00:25:36,690 --> 00:25:40,530 Um, that's full seven centimetres wide. So it's pretty coarse, pretty crude. 278 00:25:40,680 --> 00:25:49,860 Um, and you could, it could be because the physics, um, was a high enough energy that the muons that were produced, uh, traversed quite a long time. 279 00:25:49,860 --> 00:25:53,060 The detector. And you can see cameras are getting better. 280 00:25:53,080 --> 00:25:56,620 So this is a picture of the Manus detect. So it's, uh, filling the hole. 281 00:25:56,650 --> 00:26:00,040 Um, so it's actually I mean, this was actually a really, really, uh, 282 00:26:00,430 --> 00:26:04,059 a simple detector, but actually a really interesting, really interesting experiment. 283 00:26:04,060 --> 00:26:07,930 And all of the challenges were obviously understanding, uh, systematics. 284 00:26:07,990 --> 00:26:11,950 Um, I won't say too much more about that. The actual experiment itself. 285 00:26:13,060 --> 00:26:20,050 Um, but I think, I think the you really want to emphasise the UK was a very, very big player. 286 00:26:20,350 --> 00:26:30,910 Um, in the, in Sudan too. Uh, so it's a big player in Manus and a lot of that came out of those collaborations we built in the Sudan to collaboration. 287 00:26:31,510 --> 00:26:42,159 We've, we've done kind of in the former. Um, so for Manus, Sudan, two collaborators rejoined the Oxford and now we're joined by Sussex and UCL. 288 00:26:42,160 --> 00:26:50,380 And then when I returned from my sabbatical from neutrinos, um, so my time at CERN, I came to Cambridge, then Cambridge joined Manus. 289 00:26:51,380 --> 00:26:58,060 Um, and again, I think that this time what we were seeing is a shift in the physics landscape in the UK. 290 00:26:58,070 --> 00:27:06,350 So TDK was out there as well. So we were seeing a real rapid growth of um, neutrino physics in the, the UK. 291 00:27:07,100 --> 00:27:12,200 And again, I think just to give you a sense, this, this, this, this map, I like this, this, this little map. 292 00:27:12,500 --> 00:27:16,370 The UK was a really big part of the I mean, it was a US, you know, 293 00:27:16,470 --> 00:27:21,110 largest part of the collaboration was the US, but the UK was a significant contributor. 294 00:27:21,440 --> 00:27:25,829 But again, a rather small a rather small experiment. Right. 295 00:27:25,830 --> 00:27:31,280 Just coming to an end. Um, so I'm now thinking about what's the legacy of Ninos and Susanna? 296 00:27:31,290 --> 00:27:36,049 One and two. I think the the engagement of the UK on Manus, 297 00:27:36,050 --> 00:27:42,750 and it was a strong engagement from quite a large community and then the UK's involvement in the future US neutrino programme. 298 00:27:43,300 --> 00:27:48,170 I'm not sorry to underpin that engagement and the the future would still future. 299 00:27:49,280 --> 00:27:53,420 So I was trying to I was trying to think about this is only ten years ago, but it feels like a long time. 300 00:27:54,320 --> 00:28:01,750 So around 2013, a few of us, including including colleagues, um, in Oxford, were actually, um, starting to look beyond menos. 301 00:28:01,760 --> 00:28:05,870 What's what do we want to do next? Um, obviously we had a strong connection. 302 00:28:05,870 --> 00:28:16,040 We firmly built that. Um, and in fact, Giles, Giles and myself started to get interested in, uh, liquid argon liquid argon TPC program. 303 00:28:16,550 --> 00:28:21,320 Well, I hope I've got the dates right, but Oxford and Cambridge actually joined that liquid liquid argon program. 304 00:28:21,710 --> 00:28:25,970 I think it was 2013. Giles is nodding. Yeah, I think it was. 305 00:28:26,630 --> 00:28:30,800 And then and that was partly partly because the experiment actually a really interesting experiment. 306 00:28:30,830 --> 00:28:39,110 The technology is fascinating. But then we formed a deep Underground Neutrino Experiment consortium in the UK, 2015. 307 00:28:39,110 --> 00:28:42,890 I was elected as the one of the first co spokespersons. 308 00:28:43,790 --> 00:28:47,270 And very rapidly we actually got money out of government which is uh. 309 00:28:48,860 --> 00:28:53,660 So I shouldn't have noticed that. I'm not nice, actually. We had a very, very strong science case. 310 00:28:53,690 --> 00:29:01,249 Um, and part of this was actually really, um, I think part of what helped is Jo Johnson, the minister, 311 00:29:01,250 --> 00:29:06,920 then Boris's brother, um, signed the UK, US science and technology collaboration framework. 312 00:29:07,190 --> 00:29:13,490 And at that time, that was the first thing under that framework, he announced, was the UK investment in LP and FG. 313 00:29:14,580 --> 00:29:21,990 Um, so today UK is really a really big player in the 3 to $3 billion business tune project. 314 00:29:22,020 --> 00:29:30,210 The UK is not putting in 3 billion, by the way. Um, so actually along with hyper K and other investments including things like microbiome 315 00:29:30,720 --> 00:29:34,560 you train the physics in the UK is really looking incredibly exciting now. 316 00:29:34,710 --> 00:29:42,510 Um, so I think that's just that's an eye you can almost trace back some of these connections right back to Sudan one. 317 00:29:43,530 --> 00:29:47,730 I just in case people don't know what Gene is. I've got two slides. It's very similar to. 318 00:29:47,820 --> 00:29:54,570 Very similar to Minos big neutrino beam, very high power megawatt Mega one two megawatt class neutrino beam. 319 00:29:55,410 --> 00:29:59,250 This time fired at a very deep mine in South Dakota. 320 00:30:00,300 --> 00:30:03,570 But the key here is it's big. It's very, very big. 321 00:30:03,600 --> 00:30:10,230 This picture here is the one of the four large caverns that has just been excavated. 322 00:30:10,860 --> 00:30:13,990 Um, you can see a digging machine at that back. 323 00:30:14,010 --> 00:30:18,120 That little yellow thing is digging machine. These cabins are absolutely enormous. 324 00:30:18,960 --> 00:30:27,150 Um. Hopefully. Ultimately. Each of these cabins is going to host a cryostat with 17,000 tons of liquid argon. 325 00:30:27,750 --> 00:30:31,739 Um, trying to trying to picture is let's pretend it's the size of this lecture theatre. 326 00:30:31,740 --> 00:30:35,790 Actually, it's probably a bit bigger than that. Um, fill it with liquid argon. 327 00:30:36,150 --> 00:30:40,560 And if anything happens in that liquid argon, you see it in intricate detail. 328 00:30:40,800 --> 00:30:46,320 I mean, this is a beautiful, challenging technology, but a beautiful, um, a beautiful technology. 329 00:30:47,010 --> 00:30:50,440 So imagine you for all your protons sitting in your argon, one of them goes pop. 330 00:30:50,490 --> 00:30:53,550 You'll get images like that. So so impressive. 331 00:30:53,810 --> 00:30:59,450 This is actually from the, um, prototype of one of the dune experiments, um, operating at CERN. 332 00:30:59,490 --> 00:31:02,969 Moments. So final slide. 333 00:31:02,970 --> 00:31:06,900 Ready? So what? What are the physics headlines? Why are we doing this big project? 334 00:31:07,650 --> 00:31:11,100 First, it's the origin of matter. Why? Why is the matter? 335 00:31:11,100 --> 00:31:16,770 Dominance over anti-matter. Time. The mass hierarchy discovered CP violation. 336 00:31:18,470 --> 00:31:23,360 Second one is unification of forces, search for the and hopefully discover proton decay. 337 00:31:23,570 --> 00:31:28,850 Um, so we actually we are coming back full circle now we're building a big detector to do neutrinos. 338 00:31:29,150 --> 00:31:33,210 Perhaps the opposite will happen to what happened before. We'll actually get lucky and discover the proton decay. 339 00:31:33,230 --> 00:31:39,270 That'll be great. We'll see. And then, of course, there's a piece around, uh, um, uh, neutrinos, uh, 340 00:31:39,290 --> 00:31:45,410 from Galactic Supernova, which you one now it's, what, 37 years ago since the last one. 341 00:31:45,440 --> 00:31:52,850 Um, so maybe, maybe, maybe we'll get hints of, um, really interesting astrophysical information about black hole formation. 342 00:31:53,510 --> 00:31:57,680 So those are the headlines, but I think it's really nice just to see proton decay is still on the agenda. 343 00:31:58,190 --> 00:32:05,930 The hyper cameo candy physics case in Japan again has similar not not exactly the same, um, science goals, but proton decay is one of them. 344 00:32:07,320 --> 00:32:16,049 Closing a closing thought. I think these early proton decay experiments, the two on the left, um, they're quite you know, 345 00:32:16,050 --> 00:32:22,170 they look quite basically quite dated now, but actually I think they had a huge left, a huge legacy in the UK. 346 00:32:22,620 --> 00:32:27,090 Um, if we weren't involved in these experiments, uh, probably at the right time. 347 00:32:27,450 --> 00:32:31,529 It's not clear how, you know, what our program would look like today in the UK. 348 00:32:31,530 --> 00:32:38,140 So I think. I think it's, you know, just an interesting reflection. 349 00:32:38,150 --> 00:32:44,090 And clearly, I mean, Dom was a real big part of this story driving forward the interest in proton decay in the UK. 350 00:32:44,090 --> 00:32:53,120 Right, right at the beginning. So I think just on that note, um, I will close maybe on time like this one time.