So. Pleasure to be here.
Uh, just in time. Delivery? Absolutely. Um, all my complex travel plans for this week almost completely unravelled.
It's not micron's not working for that now.
All my travel plans can be almost completely unravelled today. And today was the simple day I've come in from South Africa.
London, uh, Stock Council.
So. Yes. Anyway. But I'm glad to be here. Glad I could make it. Um, yes.
I'm going to talk a bit about protocols, because this is very much a personal story, personal reflections of, uh,
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.
Now, I'm not going to talk about the physics results of neutrino oscillations because we have a presentation after this.
This this great picture here is the Sudan one. Uh, detector in its full glory.
Didn't run for very long. You probably see why. Um, but you can see these three gentlemen here.
So in front, it's Tom fields from Argonne National Laboratory.
Melvin Marshak from, uh, University of Minnesota in the back.
A very suspicious looking gentleman inspecting the hardware and not looking very happy, actually, in that picture.
Um, but that really was the start of, uh, start of that journey.
So, so this is very much personal reflection. Um, I'm not going to go too deeply into the science.
Most people in here another science, but I that I what I want to do is put this in a historical perspective of how
the search for proton decay actually shaped much of neutrino physics today.
And of course, Don was a leading figure in this area.
Actually, one of the pleasures of this putting this presentation together.
Just in time. Delivery 4:00 in this this morning. Um, was actually reading, although I read some of the papers, uh,
last night was actually reading some of the earlier papers, papers I hadn't picked up for 40 years.
And it was, uh, quite, quite fascinating. So why am I here?
Uh, the first answer's obvious. Proton lifetime is longer than the lifetime of the universe.
That is actually quite is actually quite useful. Um, so it's a useful property.
That's not really what I meant. Um, I started my DPhil here back in 1995.
Uh, experimental particle physics at Oxford. And I decided to work on a proton decay experiment in Minnesota.
Underground and very cold. This is a picture, uh, I think Mark Lancaster dagger dug out from the Royal Summer school, but, yeah, um,
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.
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.
And there are about five we didn't get, but, um, so, so so why did I go on to ground?
Um, so going back to the Don's point, what was the attraction with Sudan too?
Um, for me it was a small collaboration. Um, it was it felt much more hands on the technology, the electronics.
And actually we had a really, really great team at Oxford and just the focus.
And so the that page is a page from my thesis that someone dug, kindly dug out for me from the library at Oxford.
But that's, that's the collaboration. So it was a small collaboration.
And the group, um, the group at Oxford was also relatively small.
Uh, Don, obviously, I absolutely think, uh, John Cope and Charles Ball, um, are both both on that, that collaboration.
So it was a really nice small group, very tight knit group.
And it was uh, that was part of the attraction, but actually it was part of the science, part of the science.
And ultimately the science was this was us astro particle physics or particle astrophysics, depending where you come from.
Before it was really a big thing. So it was a really interesting time to get involved in this, this area.
You saw the field growing, uh, and gradually growing into what it is today.
So proton decay in 1984 was a seriously hot topic.
Um, this paper, which is this this was the paper I was reading actually last night.
Um, proton decay experiments. It was in the annual review of, uh, nuclear and particle, uh, science.
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.
Um, I also I tried to remember what 1984 was like.
Um, I looked, I said, I typed in what was hot in 1984.
That wasn't a good idea. Um, but then I looked at some more specific searches.
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.
I think. I think I think we're all of a sufficient generation that that is probably true.
But actually, again, it really, really took me back to, um, what it was like to be an Oxford, um, during, during those times.
So why actually, I mean, this is more, more why proton decay was the hot topic.
So if you look back to, uh, a long time ago, discovery of W and Z, um,
firmly established the gauge theory of the Standard Model, the electroweak sector of the standard.
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.
Um, and experimental data at the time. This this is not the data from the time.
Uh, this is the tidier plot. This suggested that the three main forces, the strengths of the three main forces, converged at a scale.
Um, at that time, from Dan's paper, it was ten to the 14 GV.
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.
Uh, and then Georgie and Glashow actually brought these ideas together in the context of an Su five grand unified theory.
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,
mediated by the imaginatively named at the time, X and Y bosons.
Very, very, very heavy though. Um, so obviously a consequence of this new theory was baryon number is not conserved.
If you have this theory and the proton should decay. But again, I think in Don's article, actually, it was really,
really interesting just just to make that connection because we kind of know that baryon
number non conservation is out there because where does matter left in the universe.
And it is one of the three conditions Sakharov conditions necessary to actually have matter left leftover in the universe from the Big Bang.
So this is a really nice convergence of experimental data hinting at unification, uh, and connecting to, uh, deeper, deeper symmetries.
So that's why it was, I think, a really hot topic. Um, what I going I like these old diagrams.
These aren't made with, um, LaTeX packages, as you can tell.
These these look like they were hand hand drawn. Um.
So simple. Qe5 grand unified theory. This is the underlying proton decay process.
It's not the only one. There are others. Um, you can always draw Higgs bosons in there, whatever you want.
Um, but basically, it's the process, um, goes to X producing a charged lepton and an antiquark.
And, uh, you can see the final states here.
You'll end up with the antiquark combining with the quark, and you end up with a charged lepton and a neutral meson.
It doesn't have to be. The pi can be others. Um, of course, the pi zero will then decay.
So that's one final state. Uh, there are other models.
Um, the they were available and they still are available. So if you become supersymmetric.
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.
Uh, typically, uh, an anti town neutrino.
So one of the flavour Italian notes that I was p to k plus, uh, anti-terror neutrino.
Now, you can immediately say that these two topologies are very, very different.
One is very, very light relativistic particles, uh, which, which interact electromagnetically.
And the other decay is a single, um, hydraulically interacting particle that will decay.
So the signatures are very, very different. Well, it does work.
You can then start to actually just take the Grand Unified theory and actually start to use
simple dimensional arguments to try and figure out what the lifetime of the proton is should be.
Um, so this, this, this is quite a very simplified sort of the only equation in here actually.
So you've got the very, very heavy dosage goes on to the, uh, the power force.
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.
And, and at the bottom, you've also got the, the mass of the proton to the fifth power.
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.
You put the numbers in and you get out uh,
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.
So out of this theory you get a very, very long proton lifetimes, which again is consistent with with observation.
Um, now the experimental challenge. And it is a real experimental challenge.
You're looking for signatures which are quite low energies.
There's obviously the energy scales that the proton has, and you're looking for proton decay with lifetimes of ten to the 31.
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.
Not very practical and actually not very interesting at all.
Or you can take roughly ten to the 31 protons and watch them for a few years.
Um, and the challenge then is actually getting together ten to the 31 protons or more,
quite large volume, and actually seeing a single decay, a fairly low energy decay in that huge volume.
That's the experimental challenge. So you're going to look at maybe a thousand ton detector.
Within that detector, one of those protons goes pop. You want to see it.
Um, so very very challenging. So two distinct signatures drove two different approaches.
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.
You have relativistic electromagnetically interacting particles.
And in the other case you have a slow kaon which then decays.
So there were two experiments approaches basically based on those two signatures.
So a really good way to be able to actually take a very large volume of material and, um,
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.
So this was pursued by the Emby detector in the US.
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.
Those dots are photomultiplier tubes. If Don was here today, he would be actually horrified.
So I did find a mistake in his paper.
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.
And of course, then there was the Kashmir nuclear on to k experiments in Japan.
So now known as Kashmir can go but the NDE is nuclear on decay experiment.
That's what it was designed for. Um, they're also tracking calorie misses.
So these, these these were typically, uh, mixes of steel, steel planes, drift tubes.
Protons sit in the steel when they decay, they cross the drift tubes and you see a signature.
I'll. I'll talk about Sudan, too, in a minute. Um.
So that's that. That was the experimental approach.
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.
Um, this is an I like this diagram because it was quite, quite dated.
Um, there's a plane flying there. Um, so anyway, you're looking at a very, very large detector.
So cosmic ray induced background is a problem.
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.
And you'll get a signature that could fight. It's like, um, a proton decay.
So you when you go deep underground and that's fine. Um, but you're always left with atmospheric neutrinos.
You can't get away from the atmospheric neutrinos. So what?
I think these proton vehicle experiments actually changed particle physics.
Firstly, they were large underground experiments and so on, really very large at the time.
And they were sensitive to the otherwise not very interesting neutrino induced backgrounds, but not very interesting at the time perhaps.
Now we know that's not the case.
So these experiments I think really did change the change, change the way we've been doing physics over the last years.
I made a mistake in the slides, which I spotted ten minutes ago.
Um, just stepping forward a few years. I just got this quote.
It's just a quote from a conference paper. I thought it was really interesting just because it.
Links to one of the messages I want to get out at the end. Um, so this is the situation in 1986.
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.
One experiment is being constructed Sudan. Two and two others are under serious discussions super cameo candy and ultimately obviously a very,
very important experiment in neutrino physics and proton decay, actually.
And Icarus. And obviously just noting nucleon decay had not been discovered at that time.
Um, but I think it's very interesting that these are familiar techniques,
the red ones, apart from Supercam, you can see which is actually made from water.
Um, the red ones are tracking channel images. They evolved to the Minos experiment, which I'll talk talk about.
Uh, the water Cherenkov detectors. Um, supercam you can do that is now.
Sorry. How many times evolved and supercam your fancy. And now, of course, hypothermia can die.
And then you make a new one. On the block was Icarus, which was a the first liquid large scale liquid argon TPC.
And of course, that's had a longer gestation period, but that's now evolving into the dune deep underground neutrino uh experiment technology.
So you can even even back in 1986, you see, you can see, um, the foresight of what what might come in the future.
Right. He was about to Sudan to my DPhil thesis.
So I was kind of put this is quite a personal reflection.
Deepest, darkest Minnesota and not really his deepest, darkest Minnesota.
The largest. The nearest large town Ely, Minnesota, not Ely, Cambridgeshire.
Um, it was really interesting when I was choosing projects, I had these these were the main options that were on offer.
Others were on offer as well there at Daisy, that had lots of advantages.
And I can see many, uh, Zeiss, um, uh, colleagues here, Hamburg nightlife being one of them.
I certainly I think the students who went there and enjoyed that selfie at CERN on the large electron positron collider, mountains and skiing.
I actually put that off for a few years, but it got there in the end. And then Sudan, too.
In Minnesota, lots of snow, no skiing, no mountains.
Uh, I finally remember what it was three two there.
So this is basically low alcohol. Beer was all you could get in the state of Minnesota at the time.
Um, but actually a really great an interesting group of excite scientists.
And that's obviously the attraction, including Don and that, um,
I just saw Rogers looking at me that it's not saying that there weren't great and interesting sciences.
And the other experiments, of course, there were, um, but there were.
But but but it was, as I say earlier, as part of the part of the attraction.
So that's why I did it. I think by modern day standards.
You look at the picture, this is a very blurry photograph of the detector.
This was during the the installation construction period.
Um, it doesn't look super high tech. Um, but it did actually work incredibly, incredibly well.
Um, the it's a half a half mile underground. Um, you would go down the mine carriage.
So many of us go down, lots of have been done. Lots of different line stages.
I think this is one of the more fun ones. No lights. Lots of bats flying around your head.
Uh, the rust up from the, uh, cabins on the ground. So it was always an always an interesting experience getting down.
Um. So how does it actually work? Um.
So. Yeah. So this parchments picture I took, I took a photograph of, um, the basic detector.
And it was really, really quite simple. It's just a cheap 1.5cm, um, diameter resistive tube.
Put some the put an electric field around it. So what happens?
Um, one of my points of no, I won't try and point up there.
Um, particle cross crosses that region ionises the gas, the gas.
Then the ions drift along the the field lines and you get signatures on the, uh,
wires at the end, the anodes, and you've got an induced signal on the cathode planes.
So every time a particle goes through one of these tubes, you get a electronics blip.
And then what? What you do is you sandwich all those tubes into a corrugated honeycomb structure.
Uh, this is a picture. If even looking at that picture, you can. This must have been a bad module or something.
It doesn't look very well aligned, actually. Um, but of course, it's the steel that provides all the protons.
So if one of those protons in that steel decays, particles will come out across the gas and you'll get signatures.
So very actually a very simple, very simple principle. Very effective.
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.
Yes, about 256 of them making up about a kiloton of of mass.
And that's the detector. And it's full, full glory.
Um, uh, clearly not taken with a modern, modern, modern camera, but so pretty, pretty simple technique.
But you have to have some simple techniques because you need very large, massive detectors.
So simplicity actually is is is a real benefit. So Sudan two was designed to study proton decay.
That's why it was built. Designed. Um, in some ways, it's actually a really beautiful detector.
It's a very large volume. And you have voxels, um, like pixels, but three dimensional pixels, roughly a cubic centimetre.
So that's your resolution, uh, for particles. You have very low thresholds, gas detection.
And because you're ionising the gas, you actually get good particle particle I.D. as well.
And you could then make free projected 3D images.
So these were the some of the an example of some of the event displays.
Um, just to give you a sense of what the events in this detector look like.
So you did you got the tracks, measured the tracks, or what happened to them as they scattered in the, in the medium.
Um, what about the results? Well, I think everybody knows proton decay hasn't been discovered yet, so.
So you then two did not discover proton decay? Many, many.
I mean, one of the advantages of this is you could look at many, many different k typologies because you saw the topology.
Um, all of the channels had some level of expected neutrino, um, background.
Um. And I mean Giles. Giles, who's just sitting, actually just sitting, sitting in front of where I sat down earlier,
he, you know, he was working on these analyses for, for a number of years.
And, you know, neutrino backgrounds were absolutely key.
And fruit Giles, the Oxford group actually played a long,
very significant role in actually tuning the simulations about historic neutrinos and and cosmic rays, showers and production of neutrinos.
The bottom line was what was seen in the experiment was consistent with these backgrounds.
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.
Um, but if you look at, look at the if you also then compare that.
So that is actually a pretty impressive result. Today's best limits come from the Supercam Joachim's experiments.
Um, water is very scalable. You can. As long as you like to propagate through that water, you can.
And you have enough money to pay for the nose pliers.
Um, you can scale it. So very, very large detector, very large foundational mass.
And now the current lifetime limits are up at 1010 to the 34th, ten to the 34 years.
So the proton decay. So the legacy, um.
One of the things I really enjoyed about being in Oxford, um, back in the late 80s, was actually discussions over coffee.
There was a very active culture of meeting up with colleagues and, uh, over coffee, not talking about football.
Um, actually talking talking about physics.
Um, so obviously myself and John who I saw up there, John Perkins, sometimes got, um, livened up by Mike Fowler chipping in.
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.
Uh, um uh, but actually the discussions were great, and it was really physics.
We talked about proton decay. Obviously, Don had his passion for cosmic ray physics.
So we actually talked about cosmic ray physics. My my thesis was actually more connected to cosmic ray physics and proton decay.
But actually we started talking more and more about neutrinos and neutrino oscillations.
Um, uh, and really because at this time the solar neutrino puzzle was out there,
but actually also these proton decay experiments were sort of starting to see anomalies, not all of them.
Some of them saw things that were consistent with the standard normal oscillating predictions, but others were showing hints.
So we were starting to see hints that the background of proton decay was was actually the signal for something else.
Uh, something else we now know is extremely, extremely interesting.
So what I think and I will actually I'm going to because I'm going to argue this.
I think you could argue that.
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,
with with Japan, the members of the Sudan two collaboration.
They were actually key in the development for the concept of P8 seven five.
I hope I've got the number right. Uh, a long baseline neutrino oscillation experiments at at Fermilab.
And this ultimately resulted in the formation of the Minos collaboration.
Um, I think that was helped.
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.
So, Stan, that was one of the leading figures in the development of the proposal and the experiments.
It also turns out that if you start at Fermilab. Sudan.
The Sudan mine is about 730 miles away. That turns out to be just about the right distance.
Not perfect, but to study neutrino oscillation oscillations from you on neutrinos.
Um, you've got to go underground again. So you go back to the Sudan mine.
Um, so this was a second generation long time neutrino oscillation experiment.
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.
You smash 120 GeV protons into a target.
Uh, three create a beam of neutrinos. They fly across.
Well, actually, under, um, under the Midwest, under, um, uh, Lake Superior.
And then you detect those neutrinos with big detectors.
Uh, one of them you put right near the source, and then one of them you put down the mine.
So that's the basic experiment. And then you compare what you see close to the to the source and a long way away.
And if they're different, something's happened to the neutrinos they've oscillated.
I think. I think Paul will say more about that in his his presentation.
Again, these detectors were actually fairly simple.
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.
The simple, because the thing you're aiming for is mass. You need to get a lot of mass in your detector.
Um, so this is this is the detector. Basically, it's planes of steel and, uh, interlaced with scintillator.
So 484 one inch thick steel planes with one centimetre scintillator in between.
Somewhat similar to the Sudan idea. All of your protons.
What most if instead still if something decays, it will cross some scintillator,
give a flash of scintillation scintillation light, and then you read it out so you get a signal.
Um, in this case in MTC. So lots of layers.
Just to give you a sense, the that's not that that's a bit of plastic at the bottom.
That is the basic detector. It's detecting elements. And then you have to put a bunch of TMT on the end of it.
Um, that's full seven centimetres wide. So it's pretty coarse, pretty crude.
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.
The detector. And you can see cameras are getting better.
So this is a picture of the Manus detect. So it's, uh, filling the hole.
Um, so it's actually I mean, this was actually a really, really, uh,
a simple detector, but actually a really interesting, really interesting experiment.
And all of the challenges were obviously understanding, uh, systematics.
Um, I won't say too much more about that. The actual experiment itself.
Um, but I think, I think the you really want to emphasise the UK was a very, very big player.
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.
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.
And then when I returned from my sabbatical from neutrinos, um, so my time at CERN, I came to Cambridge, then Cambridge joined Manus.
Um, and again, I think that this time what we were seeing is a shift in the physics landscape in the UK.
So TDK was out there as well. So we were seeing a real rapid growth of um, neutrino physics in the, the UK.
And again, I think just to give you a sense, this, this, this, this map, I like this, this, this little map.
The UK was a really big part of the I mean, it was a US, you know,
largest part of the collaboration was the US, but the UK was a significant contributor.
But again, a rather small a rather small experiment. Right.
Just coming to an end. Um, so I'm now thinking about what's the legacy of Ninos and Susanna?
One and two. I think the the engagement of the UK on Manus,
and it was a strong engagement from quite a large community and then the UK's involvement in the future US neutrino programme.
I'm not sorry to underpin that engagement and the the future would still future.
So I was trying to I was trying to think about this is only ten years ago, but it feels like a long time.
So around 2013, a few of us, including including colleagues, um, in Oxford, were actually, um, starting to look beyond menos.
What's what do we want to do next? Um, obviously we had a strong connection.
We firmly built that. Um, and in fact, Giles, Giles and myself started to get interested in, uh, liquid argon liquid argon TPC program.
Well, I hope I've got the dates right, but Oxford and Cambridge actually joined that liquid liquid argon program.
I think it was 2013. Giles is nodding. Yeah, I think it was.
And then and that was partly partly because the experiment actually a really interesting experiment.
The technology is fascinating. But then we formed a deep Underground Neutrino Experiment consortium in the UK, 2015.
I was elected as the one of the first co spokespersons.
And very rapidly we actually got money out of government which is uh.
So I shouldn't have noticed that. I'm not nice, actually. We had a very, very strong science case.
Um, and part of this was actually really, um, I think part of what helped is Jo Johnson, the minister,
then Boris's brother, um, signed the UK, US science and technology collaboration framework.
And at that time, that was the first thing under that framework, he announced, was the UK investment in LP and FG.
Um, so today UK is really a really big player in the 3 to $3 billion business tune project.
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
you train the physics in the UK is really looking incredibly exciting now.
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.
I just in case people don't know what Gene is. I've got two slides. It's very similar to.
Very similar to Minos big neutrino beam, very high power megawatt Mega one two megawatt class neutrino beam.
This time fired at a very deep mine in South Dakota.
But the key here is it's big. It's very, very big.
This picture here is the one of the four large caverns that has just been excavated.
Um, you can see a digging machine at that back.
That little yellow thing is digging machine. These cabins are absolutely enormous.
Um. Hopefully. Ultimately. Each of these cabins is going to host a cryostat with 17,000 tons of liquid argon.
Um, trying to trying to picture is let's pretend it's the size of this lecture theatre.
Actually, it's probably a bit bigger than that. Um, fill it with liquid argon.
And if anything happens in that liquid argon, you see it in intricate detail.
I mean, this is a beautiful, challenging technology, but a beautiful, um, a beautiful technology.
So imagine you for all your protons sitting in your argon, one of them goes pop.
You'll get images like that. So so impressive.
This is actually from the, um, prototype of one of the dune experiments, um, operating at CERN.
Moments. So final slide.
Ready? So what? What are the physics headlines? Why are we doing this big project?
First, it's the origin of matter. Why? Why is the matter?
Dominance over anti-matter. Time. The mass hierarchy discovered CP violation.
Second one is unification of forces, search for the and hopefully discover proton decay.
Um, so we actually we are coming back full circle now we're building a big detector to do neutrinos.
Perhaps the opposite will happen to what happened before. We'll actually get lucky and discover the proton decay.
That'll be great. We'll see. And then, of course, there's a piece around, uh, um, uh, neutrinos, uh,
from Galactic Supernova, which you one now it's, what, 37 years ago since the last one.
Um, so maybe, maybe, maybe we'll get hints of, um, really interesting astrophysical information about black hole formation.
So those are the headlines, but I think it's really nice just to see proton decay is still on the agenda.
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.
Closing a closing thought. I think these early proton decay experiments, the two on the left, um, they're quite you know,
they look quite basically quite dated now, but actually I think they had a huge left, a huge legacy in the UK.
Um, if we weren't involved in these experiments, uh, probably at the right time.
It's not clear how, you know, what our program would look like today in the UK.
So I think. I think it's, you know, just an interesting reflection.
And clearly, I mean, Dom was a real big part of this story driving forward the interest in proton decay in the UK.
Right, right at the beginning. So I think just on that note, um, I will close maybe on time like this one time.