STFC-RAL-CR03 R61: I'm going to talk about extreme field physics using high-powered lasers. And this was back many years. And Bill Scott there, that's just come into the room reminds me of some of the work that we did when we were working in the center for fundamental physics. So we had this set of fundamental physics. We discussed some of these outlandish ideas that seem to be so far in the future that we've never actually achieved anything. But now I'll show you that
STFC-RAL-CR03 R61: we're now knocking on the door of some of the interesting things that can be done, and before doing so, I'd like to just
STFC-RAL-CR03 R61: acknowledge all the people that I've worked with on the various topics I'm going to be talking about, and I'll make mention to Jack Parody, who's here he's in the audience just now, and he'll keep me straight when it's when I'm talking about a laser. He knows more about lasers than I. Dori is also
STFC-RAL-CR03 R61: key to this, because he was one of the key founders of some of the experiments that we've proposed actually, and Ava boss is now leading up
STFC-RAL-CR03 R61: some of the experiments that we're working in.
STFC-RAL-CR03 R61: It's
STFC-RAL-CR03 R61: A lot of the work has been taken from some of the students we've had over the last few years, and so A lot of it is due to them as well. So I'll talk about them and what they did. But what I'll talk about it initially is what is extreme physics and why do we think we could get close to it using, say, high powered photon beams that are coming out of these new buildings that are being built. So you have a lot of
STFC-RAL-CR03 R61: inconvenience. You're told to go home, etcetera. The the buildings have been closed down because they're changing power over and things like that, or the Internet's not working. And that's all because Epac and Vulcan 2020. We've seen big holes out here. That's for Vulcan. 2020. Epac's finished, and it's out. It's robbed some of the car Park space that you used to park in, and it's now there, it's now
STFC-RAL-CR03 R61: You can fit it out with lasers. And those lasers actually will probably be up and running next year. Hopefully, we'll be able to look at the lasers in a year's time and come back to some of these pro- problems.
STFC-RAL-CR03 R61: 1st of all, we talk about the pair plasma experiment that we've been doing at Cern as well. Then I'll go into photon photon scattering something that Bill Scott and I looked at many, many years ago. Photon Ise and coupling. It's a new thing that we've been starting to look at, and then photon gravitational wave coupling.
STFC-RAL-CR03 R61: which is more or less very similar to the photon axing, coupling, coupling. And then this past one neutrino coupling, they're all very similar. The equations basically are identical. So if you solve one, you solve them all.
STFC-RAL-CR03 R61: And so I'll just explain that as we go through. So what is strong fields, well, strong fields can be found in astrophysics, and probably one of the strong examples of that is these magnetars and they magnetic fields are about 10 to the 14 Gauss, and that's very near the chronic limit. So we're generating very large amounts of electron posits from plasmas in these fields of the star itself.
STFC-RAL-CR03 R61: And so we're looking at
STFC-RAL-CR03 R61: the ability to be able to generate electric fields. We're looking at physics of the vacuum, basically using these high power lasers. And this is an example of, say, extreme magnetic fields in astrophysics. Now.
STFC-RAL-CR03 R61: I did mention photon photon scattering. Now I know that you guys in cerm have detected photon photon scattering. But you've used it using collisions between proton fields that the elements see the electromagnetic fields, the virtual particles that are generating as you climb the particles together are actually scattering photons. Now, that's a very intense environment. I'm going to show you some experiments that we
STFC-RAL-CR03 R61: proposing that haven't been done yet, but proposing to do that are probably not as intense, but in a much more controllable, or
STFC-RAL-CR03 R61: wouldn't say that a much more amenable
STFC-RAL-CR03 R61: environment where you can actually stand next to the the experiment, and fiddle around with it. Gallery versus another area where you get very high yields.
STFC-RAL-CR03 R61: and you also get very strong fields and plasmas. These are the 1st papers that were produced to show that you could actually get very intense fields by colliding, say, 2 laser beams. I'll talk about the intensity in a minute. And you're getting vacuum production of electric positron pairs here. So these beams have been known for a long time in the simulations. No one's done these experiments yet. Same with the solid targets.
STFC-RAL-CR03 R61: That is something I will mention. We do actually generate electron positron pairs from the solid.
STFC-RAL-CR03 R61: These are plasma interactions, and that's something I'll come back to later on.
STFC-RAL-CR03 R61: So all kicked off more or less. About 19 middle of the 19 eighties, when General Moreau and Donna Strickland actually came up with this idea of chip, pulse, amplification, chip amplification means that you take a short pulse, stretch it, amplify it, then compress it again, and that gets you up to very high intensities. And at the moment the Raul machines, the final group, the ones are going to be talking about that Cpap and
STFC-RAL-CR03 R61: Balkan. They are at probably reaching the highest intensities. We'll go up to about 10 to the 22, which is round about here, but we'll be able to shoot up to about 10 to the 2210 to the 24 watts per square centimeter. Now, that's still quite a long way from the nonlinear Qed. Limit of, about, say, 10 to the 29 watts per square centimeter.
STFC-RAL-CR03 R61: and there are trips that we can do to get up to that intensity. We'll see how we can do that in a minute. So
STFC-RAL-CR03 R61: okay.
STFC-RAL-CR03 R61: it all started again with Kibble and Rudy Powell's here. This is going way back. Rudy Powell's in 33, and Kibble in 66. I remember when I was doing my Phd. I was reading papers that Kibble had written on laser plasma interactions or laser matter interactions. He would look at how a laser would interact with electrons. And these were very insightful papers actually, but that work, more or less, remained dormant for many, many years, until
STFC-RAL-CR03 R61: these high power lasers came along. And the key parameters is this parameter here, which is zeta, which is basically the oscillary velocity of the electron in these very high fields. So if you take one of the lasers which is operating about 10 to 18 watts per square centimeter. Immediately an electron in that laser will be accelerated to the speed of light or very close to the speed of light.
STFC-RAL-CR03 R61: That's 1 of the key parameters. The other parameter that they wrote down is your data here, and that is the comparison between the trigger field and the the laser field. Here the laser field is the Erm Rns field, and that's a key parameter as well. So we're trying to
STFC-RAL-CR03 R61: and get that value up as high as possible. And as we know, equipment is 10 to the 16. So how do we actually get to that value without pushing the limits of the lasers, which we can't do at the moment. So the the trick is to use this idea of, say, the intensity is not the right scalar. So if we've got say, the
STFC-RAL-CR03 R61: opportunity of generating a Gev electron beam. So we've got a Gev electron beam, say 10 gev. A gamma of about 10 to the 3 to 10 to the 4.th Then we can take the the boosted frame here, and we can increase the intensity. So the intensity I
STFC-RAL-CR03 R61: dash will go up by gamma squared I, and we're getting then close to the schwing of limit. So in the boosted frame. The the field that you have is at the swing of limit, even though in the logic frame it's still at 2010 to 22 watts per square centimeter. So using an optical Petawatt system, which is the laser that I'll mention in a few seconds.
STFC-RAL-CR03 R61: With this trick of actually, we can get up to intensities close to the limit or even higher. So that's the trick that we're going to achieve. So the there's been great progress in the last 20 years. This is a very busy slide, but I'll just talk through it. We start here 2,004. This is when we saw the 1st
STFC-RAL-CR03 R61: beams of electrons that are being accelerated. These are unique beams, so that you've got an energy of about say, 100. Well, it's about 85 or something. And that's the the divergence of the beam. But these very well collimated beams that are being generated. If you look at the history. Here it goes up to 2,006. We're up about a Gv. Now. 2014. Here, we're about
STFC-RAL-CR03 R61: 4 or 5 Gb. And then. Now we're up at 10. Gb, so we're we're reaching the the limits of some of the
STFC-RAL-CR03 R61: problems that we've got one of the things that will limit that is defacing and running out of energy. That's why we're going to be building a much more powerful laser, much more energetic laser. So we'll be
STFC-RAL-CR03 R61: getting regular beams at 10 gev. Out of these labor systems, and they'll be operating at hers.
STFC-RAL-CR03 R61: So they're basically miniature accelerators. The layers, the accelerators were gone
STFC-RAL-CR03 R61: are of the order of centimeters in size. Of course the laser takes up
STFC-RAL-CR03 R61: a huge room I mean the lasers. I think it's in the
STFC-RAL-CR03 R61: is it? Upstairs. Yes, they're all upstairs. But the beams went down into the experimental chamber. So the conventional accelerator is this one here? Another accelerator, and it's about a meter for about 40 megavs per meter, whereas this one is about 2 cm for about 100 giga volts per meter. So these are
STFC-RAL-CR03 R61: incredibly efficient at getting up to the energies that we require.
STFC-RAL-CR03 R61: And so it's not difficult. People have been doing this now for about 20 years, and we can actually really produce huge amounts of particles actually, operation. So that's something that we're looking forward to switching on the laser over there. We're already producing these beans in Gemini, which is over there, and that will close down eventually.
STFC-RAL-CR03 R61: So the laser that is being fitted out in this building now the car park was it's about 106 million pound investment, the site. It's going to be one Petawatt laser operating about 10 hertz.
STFC-RAL-CR03 R61: and it's basically designed to produce 10 Ged electron beams. And these electric beams will be used for fundamental physics as well as well as radiation sources for other material size, diagnostics, etc. Etc. So we're going to be exploiting these lasers in this
STFC-RAL-CR03 R61: that are going to be built over here. This is just when we started. This is the 1st hole that we stopped. That's Donna Strickland. I think she was the 1st person to dig this big hole for this the cement that she's in the belt browser, by the way, so she.
STFC-RAL-CR03 R61: So I'll skip through this because we don't really need to worry too much about it. But just
STFC-RAL-CR03 R61: to tell you that laser blocks there. They all come down into these experimental halls
STFC-RAL-CR03 R61: and you end up with electron beams or X-rays coming out of a very compact about a meter or so in size, accelerator stage.
STFC-RAL-CR03 R61: and of course, Vulcan, which is not finished yet, and it's undergoing all this construction at the moment all the people are in there digging holes. You've seen all the goodness knows the holes are products. Who can tell me what all these holes are for, but but it's an old laser. It's the original laser that was put on site in 77. But now we've taken it through decades of
STFC-RAL-CR03 R61: upgrade, and we're now building or hoping to build a 20 petawatt 20 kilojoule laser in that building that's being constructed at the moment, and that will be for extreme field size and high energy density visits. So we'll be able to reach the highest intensities of any laser that's on the planet at the moment. And that's something that we're looking forward to in about 4,
STFC-RAL-CR03 R61: I think, about 4 years time. So we're really pushing the boat out and going to these intensities. So both in 2020 science, it's very, it's very, very important. Actually, we'll get 20 megawatts and 20 kilojoules
STFC-RAL-CR03 R61: of energy available to us, and one of the important things that we're going to be looking at is quantum electrodynamic processes. So we'll be able to get to the close to the schwar limit by doing this training
STFC-RAL-CR03 R61: problem and getting very close to parameters where you have to look at nonlinear. Qed, no longer is Qed going to be a linear process, it will have to be fully nonlinear. We still really don't understand what that's going to be in terms of science, fundamental physics. That's the stuff that Bill and I talked about many years ago. We're going to be talking about the vacuum nonlinearity, so we'll be able to produce
STFC-RAL-CR03 R61: nutrients of space where the vacuum is actually nonlinear, we'll be able to do experiments in there. I put down this thing called radiation. That's the what we believe to be the laboratory equivalent of, say, hockey radiation.
STFC-RAL-CR03 R61: And of course not. Qv
STFC-RAL-CR03 R61: there's going to be other things going on. So there's no states of matter. Warm Reds matter, so I won't talk about any of those. But we will be talking about astrophysical problems in the next few seconds. In fact, maybe that problem there. So I'll just
STFC-RAL-CR03 R61: So it's going to laboratory astrophysics. For a long time we've been trying to get to a situation using lasers where we can produce useful electron deposits on beams that can actually start questioning some of the laboratory astrophysics problems that they're solving, or some of the key issues that they've tried to address without actually doing an experiment.
STFC-RAL-CR03 R61: And so a number of the experiments that we've been trying to look at involve jets. So these are electron positron jets. And
STFC-RAL-CR03 R61: a key thing here is to look at the laser jet. This is an interesting problem, because there's a deficit of Gep photons coming from the jet, and one of the experiments that Jack here pioneer himself, which I'll talk about in a second, was to actually understand how an intense electropositron beam
STFC-RAL-CR03 R61: of material or plasma would move through an interstellar medium. And what are the instabilities associated with it? So we're really interested in finding out about this problem. And so this is the laser jet. So the laser jet is producing, say, Tev photons. These Tev photons
STFC-RAL-CR03 R61: are actually interacting with the background infrared and then produce a pair of cascade. So the pair cascade is the pair of plasma that's moving through intergalactic space here. And by the time we see it. It's actually just the photons that we see. We don't see the jets at all we've seen in the photons, but the idea is, if these jets are actually coming out of this. Say, Blazer itself.
STFC-RAL-CR03 R61: They should be actually interacting with cosmic microwave background, and because they would be generating upshifted and producing Gev photons
STFC-RAL-CR03 R61: that's not seen, or there's a deficit of the photons. So we don't see that.
STFC-RAL-CR03 R61: So we actually thought, well, this is a very interesting experiment to do so. Jack was working at Oxford at the time, and he put together a very comprehensive team of people to look at some of the instabilities, and so the most important instability, perhaps, is this filamentation instability. It's a beam plasma instability. It's a positron beam, electron beam positron plasma going through interstellar or intergalactic medium.
STFC-RAL-CR03 R61: And it's interacting with plasmas there. And what happens is that it would actually filament and create magnetic fuel structures. So this would be an
STFC-RAL-CR03 R61: a reason why we don't see
STFC-RAL-CR03 R61: so so this is a neutral business. And what you find this and this is
STFC-RAL-CR03 R61: The example of the blue would be electrons, and the red is positive ones, perhaps in this image. But they separate because you've generated. Small magnetic fields are amplified, and then they're generated as a result of the instability amplified, and then the scatter. And so that was the
STFC-RAL-CR03 R61: that was one of the solutions to explain why we don't see these Ged
STFC-RAL-CR03 R61: good points coming from place objects.
STFC-RAL-CR03 R61: That was not the case. When we measured this, we didn't see enough magnetic field to actually explain the
STFC-RAL-CR03 R61: the physics of what was going on. So there was experiments done. And this is just going back to producing electron posits on jets. Because one of the things we have to look at this using a high powered laser. So people have been doing this for years now they've been trying to generate electron posits on beams from laser matter interaction. This is a laser.
STFC-RAL-CR03 R61: the laser interacting with the plasma
STFC-RAL-CR03 R61: generated through a Wakefield accelerator, an electron beam, and that electric beam is interacting with high Z material here and that generating electron positive.
STFC-RAL-CR03 R61: meaningful
STFC-RAL-CR03 R61: articles. Now, none of those were very successful, for the very reason that you're not producing a plasma. So these these beams that are being generated are just individual particles. So they're not actually generating what we'd call a plasma itself. And we'll come to that in a few minutes. What constitutes a plasma?
STFC-RAL-CR03 R61: You have to have enough particles in the biosphere to make it a plasma. If you don't have enough plasmas in the biosphere which we'll come to in a second. Then it's just a collection of individual particles. And it's just these particles don't
STFC-RAL-CR03 R61: interact collectively. And that instability I talked about was a collective instability. A lot of collective instabilities happen.
STFC-RAL-CR03 R61: And that's elevators of the possible interactions as well. So these these experiments.
STFC-RAL-CR03 R61: couldn't be used to do this, the experiment that we're proposing to do. And so we had to go to Sam, and we use the
STFC-RAL-CR03 R61: Sps. And using the facility. It's called the High Rock Map Facility. Jack built down into the chair, down to the tunnel.
STFC-RAL-CR03 R61: and he set up a comprehensive experiment which is about at the moment. It's about 3 meters long plasma. And we're producing electron positron pairs
STFC-RAL-CR03 R61: by taking the say Svs, which is 440 Gev. Photons, smashing it into a low Z target, and then the Hadrons will then cascade and produce Gev photons coming out of the
STFC-RAL-CR03 R61: target. There, now this, this is not the target. This is just a representation. These targets are about a meter long or something like that, and I think the best target now is about graphic. We you haven't used since the 1st exam.
STFC-RAL-CR03 R61: So the the experiments are using just long meter long and graphite tiles, and we're producing large amounts of electric positron
STFC-RAL-CR03 R61: being of plasma coming back. And this is this is constituting the
STFC-RAL-CR03 R61: where we are just now. So this is the positron. Yield along here. This is the positron density along here, and what we have is the
STFC-RAL-CR03 R61: the calculation is done through the measurements of the by.
STFC-RAL-CR03 R61: and the number of particles in the device here
STFC-RAL-CR03 R61: dictate. If it's a plasma, or if it's just a collection of
STFC-RAL-CR03 R61: particles. So the device here is just a screen distance. So if you think of particles are just a collection of charges, and do equal and opposite charges, then you think they will try and cancel each other out. And they do. And they're trying to form a device here. The device here is determined by the temperature of the particles as well as the number density.
STFC-RAL-CR03 R61: and that if the temperature is too small and number density is too high, then you will not form a very large device here, so the number of particles n plus and minus will be relatively small, and it doesn't constitute a plasma. It's just individual particles that are moving close to the sphere of light. So we had to get over that hurdle. And we're successful in the domain where we can really call this
STFC-RAL-CR03 R61: an electric positron basilon. So any instability that's going to happen will be through a collective process.
STFC-RAL-CR03 R61: And this is going back to the the idea of be
STFC-RAL-CR03 R61: the jet propagating through intergalactic space, and it's generating some stability here. And this is a favorite mechanism. The filamentation mechanism I talked about was a favorite mechanism to generate local magnetic fields which would then scatter the particles and prevent them from generating significant amounts of
STFC-RAL-CR03 R61: Ged photons that we would see. So we don't see them. So there's something else happening. So the other solution to this problem is that the region is already magnetized. So what we've got here it could be something like a primordial field, and that was something the astrophysicists didn't really
STFC-RAL-CR03 R61: think would be possible, because they were thinking the fields were too small to see these primordial fields too small to scatter the photons. But we believe that there is local pockets of strong fields in space that could actually do this. And it seems to me.
STFC-RAL-CR03 R61: So that's a summary, more or less. Say that. And oh.
STFC-RAL-CR03 R61: sort of achieve this. But what we're trying to do is achieve it in a laboratory that's going to just meters away from here
STFC-RAL-CR03 R61: and using laser beams. So we've got 3 laser beams that are coming in to an intersection point there and then we're detecting a scattered photon that's coming out. So these beams of photons are coming into a scattered region here, and they'll
STFC-RAL-CR03 R61: reduce in the vacuum.
STFC-RAL-CR03 R61: a nonlinear signal that will scatter this beam into this beam. So that's the 1st that will be the 1st direct, real photon photon scattering. We can argue about this with the Sam people if it's real photon photon scattering because you're generally big virtual photons, and you have to live in your collision region.
STFC-RAL-CR03 R61: So this would be I think the 1st detected direct photon photon scattering experiment in the vacuum. Now, this experiment, if this is possible, we can do this, we'll be able to do this other experiment, which is a double slip experiment. We can actually then send through laser beams and set up a standing wave.
STFC-RAL-CR03 R61: and this standing wave will be regions of very high intensity, low intensity, high intensity. So those high mode intensities would appear to another laser beam, as being changes in refractive index. So they'd be normally a change in refractive index. And you get a double or a young slip kind of experiment going on. So
STFC-RAL-CR03 R61: change the
STFC-RAL-CR03 R61: the setup and see the nice airy pattern that you get. So the photon photon scattering. I'll give some some background here because it is quite important. So we use this Heisenberg Euler Lagrangian bringing in this gap here. This is the sort of.
STFC-RAL-CR03 R61: and this allows us to couple say paralytic fuels with
STFC-RAL-CR03 R61: electric fields with magnetic fields direction. And we can write down, say, the equations for the electrodynamics. And we end up with this equation here, so we'll get beams e. 1 at the electric field of winds of one E, 2. Electric field of laser, 2 and E 3. Electric field of laser 3. And that will be the scattered wave of the that will get rise to the scattered wave. E. 3. So this is like a 3rd order.
STFC-RAL-CR03 R61: nonlinear susceptibility. But this is due to the vacuum. And this work was done. Here
STFC-RAL-CR03 R61: some students working in the center for fundamental physics. That was way back 20 years ago now, and this was done here. But at that time we never thought that the lasers we require to do, this experiment would be built. So what's roughly the dimensions of that spot? Yeah, it's a it's a, it's a spot that. And this is a very crucial point in this, because
STFC-RAL-CR03 R61: this is an ultra high vacuum region. And what I didn't say was that we're developing techniques to create ultra high vacuum by sending in a pulse laser which will sweep out any particle that is in there before these other particles collide. I mean, it's a tall order, but I'm not sure by the experimentalists that they can do it.
STFC-RAL-CR03 R61: So this is the basic experiment you've got. k, 1 k, 2 main beams coming in. K, 3, then scatters from the nonlinear vacuum here. So you get a nonlinear refractive index and it scatters into K 4. So that's a 4 wave type of scattering process. And it basically, it's exactly the same as you would do for 4 wave scattering nonlinear crystals
STFC-RAL-CR03 R61: in Labarge.
STFC-RAL-CR03 R61: So what we've got here is the powers, the number of scattered photons here. This is same as what I've already talked about, but this is the power of the laser. So the power of laser is half a Petawatt. We did this calculation years ago. We're getting about a quarter of a photon coming out each collision. We're getting quarter of photon, so we'd have to do many, many collisions to build up statistics to see the photons of the scattered photons at one Petawatt. We're getting 2 photons out.
STFC-RAL-CR03 R61: These are very difficult photons to detect. So using. And these are these are powers that we've already got. And the experiment has not been done because we don't think it's possible to just measure those very, very small values of
STFC-RAL-CR03 R61: scattered photons. So we're going.
STFC-RAL-CR03 R61: We've waited until we've got the 20 Petawatt laser. And this is an example of what we've got, 5.5 2.5 5 1025, 30 petawatts. As you go up in power you can see that you've got many more photons to detect. Now, the difference between this column and this column is that you've got 2 pump waves and 3 pump waves. So if you've got 2 pump waves, in other words.
STFC-RAL-CR03 R61: k, 1, say k, 1 and K 2, discussing from that vacuum, using K 2, or in the vacuum to produce K. 3, and that would probably be a weaker effect than if you have used 4
STFC-RAL-CR03 R61: photon screen into the vertex there. But that's a difficult thing, having 4 photon views
STFC-RAL-CR03 R61: focus to the same spot at the same time is quite a tricky thing. But the technology is developing very quickly. So what we're looking at here is the number of photons that you start to see as you go up in power. So it's a matter of just waiting, and a number of groups around the world are waiting to do this experiment as most people are trying to build. I believe the Chinese are
STFC-RAL-CR03 R61: trying to do a hundred pages. There's a an interesting twist to this, and
STFC-RAL-CR03 R61: this is a twisted laser beam. It's angular momentum beam, so it's twisted.
STFC-RAL-CR03 R61: and this would give us the ability to actually see a scattered photon from all the other photons that are in the system, because it would have a unique spin to it. So we'll be able to identify this Ortho angle and momentum photon that's coming out rather than just look at the energy of the photon. This would tell us something about the
STFC-RAL-CR03 R61: scatter brought on itself. So this is an interesting twist.
STFC-RAL-CR03 R61: So you see, virtually the same as what I've just been talking about all these processes are very similar, because they all go through the same kind of engine. So we're talking about.
STFC-RAL-CR03 R61: we don't. I've seen a problem now ended
STFC-RAL-CR03 R61: here we've got a 3 way kind of coupling process. We've got a laser, a very intense laser bead coming in, and it scatters from the vacuum into another photon, only a gamma and an axon, which is the energy only here. So you've got the possibility now of driving
STFC-RAL-CR03 R61: the vacuum into a nonlinear state which would then generate an axion. So this is something that was done a few years ago, and it's 1 of the experiments that's planned as well. So this experiment will actually look at the possibility of driving an axion
STFC-RAL-CR03 R61: with a very strong electric field that's coming from the laser. So
STFC-RAL-CR03 R61: again, we're using this Lagrangian here. These are the 2 key terms here, and A is the amplitude of the axiom. E is the one of the amplitude of one of the electromagnetic waves, and B is the amplitude of the magnetic field, of the amplitude of the other electromagnetic waves. So when you take these waves couple them together. It's
STFC-RAL-CR03 R61: something that we've been doing for a long time, but not with axioms, but with plasma most of the time. E. Naught would be a plasma wave, and we would couple a laser beam into a plasma, generate a plasma wave, for instance, that plasma wave could be the wake field, and you're generating an accelerated. I'm sorry. A weight field that's going, perhaps close to the sphere of light.
STFC-RAL-CR03 R61: and you can then accelerate particles using that plasmatic because it's carrying electric field in the same direction as it's propagating it.
STFC-RAL-CR03 R61: Identical equations. So we can just carry through the analysis. These are these equations are very familiar to anyone that's working in laser-plasm interactions, except we'll just replace a here with Sorry, the the
STFC-RAL-CR03 R61: we'll replace the plasma wave with A, which is the axion field now, and we can do go through. Calculate a dispersion relation. And this dispersion relation tells us that we've got scattering of a laser beam in the vacuum into an axiom plus another laser beam.
STFC-RAL-CR03 R61: and that would give us the opportunity then to study, perhaps actions at different
STFC-RAL-CR03 R61: masses. So this is again the mass of the axiom.
STFC-RAL-CR03 R61: and this is the the coupling here. And so we've got this
STFC-RAL-CR03 R61: today. We would probably be a way up here way off where everybody else's. This is the the limits of the of the accident mass. So
STFC-RAL-CR03 R61: if we actually push it down to here, we're getting closer to where there's gaps in the measurement of axion mass, so there's no axions round about here at the moment, or no one's doing experiments in this region here, so we could probably start to push the limits of that.
STFC-RAL-CR03 R61: And you'll recognize that task. Here is the experiment that was carried out in in sound.
STFC-RAL-CR03 R61: And that's looking at the the sound axiom sort of telescope.
STFC-RAL-CR03 R61: So we were looking at from the sun, coming as a result of the sun, can be at the end.
STFC-RAL-CR03 R61: So this this brings me to the experiment that we did do. We haven't done these experiments yet, because we're still far away from the limit that we need to get to the new lasers coming along this limit will be actually reduced here. So this is the experiment that was conducted again. This is done.
STFC-RAL-CR03 R61: using a laser. But it was a a free electron laser. So it was an X-ray laser
STFC-RAL-CR03 R61: jack designed the equipment here and the laser. 3 electron laser phasing was used to interact with the crystal plane here. So the crystal plane has got a very large electric field. Germanium field. The Germanium crystal has a field of about 10 to 11 volts per meter. So the magnetic field
STFC-RAL-CR03 R61: parallel to that electric field on the plane of the crystal would give rise to an axiom. So we're seeing an axiom coming out. You also see the gamma ray coming out here because the gamma ray will be
STFC-RAL-CR03 R61: bent by crystal as well, so that you put a shield here, which means that you've got light shining through. Wall experiment. So it's a light shining through. Wall experiment stops the light going through and then through, reconvert in the almost identical situation you've got here into a photon and you detect the photon. So that experiment has been successfully completed and the work was written up and published in the Ml.
STFC-RAL-CR03 R61: And that was it. Those were the limits. So we're we're with the European excel. We're out here. So it's a region where no one is looking, actually. And of course this is the Ur.
STFC-RAL-CR03 R61: They-, they do exist. So we're out here with the 10 to the minus 4. But that's an older plot, is it? Yeah.
STFC-RAL-CR03 R61: So they're close to. No?
STFC-RAL-CR03 R61: Oh, we'll have, I'll fix that.
STFC-RAL-CR03 R61: Thanks for. So again.
STFC-RAL-CR03 R61: 2020 min. So, okay, this is our executive. So this is this is all due to a paper that came out in about 62,
STFC-RAL-CR03 R61: yes, and time effect. And it's very similar to the axiom effect. Actually, because with the axiom, you've got the possibility of generating the axiom by putting an electromagnetic wave or through a magnetic field. You do the same thing. Here you get the graviton, which is the age strain of space time here
STFC-RAL-CR03 R61: is interacting with magnetic field generates the photon. So what we've done is we've taken this idea and reverse it. So we'll take the photon. Put it through. Not a magnetic field, but we'll put it through a scattering. There is another laser
STFC-RAL-CR03 R61: to the laser here, scattering of that gravitational wave.
STFC-RAL-CR03 R61: and it's scattering in a similar way to the parametric instability. So you're scattering from this gravitational wave. And this wave is picked up in this detector. So the the frequency of the wave is
STFC-RAL-CR03 R61: that you detect is omega gravitational wave frequency minus omega of the of the laser beam, and that actually will get this into a regime where the
STFC-RAL-CR03 R61: the frequencies are way much higher than anything that's ever been looked at. We've always been contemplating looking at these frequencies. These are in the optical regime of
STFC-RAL-CR03 R61: of the updates of ways, and I'll show you the plot here. This is liable.
STFC-RAL-CR03 R61: This is where we are just now. This, this is the plot that they've been able to
STFC-RAL-CR03 R61: detective gravitational waves. You can see the way down here in the tensor perch region, whereas we are way up here with the lasers.
STFC-RAL-CR03 R61: If you go to Terah that way in terms of frequency, you can. You're not pushing very far down, but you can see that the next upgrade of lasers will be getting close to what we think is a detectable signal. So the next upgrade of high powered lasers which is not going to be in this country. It will be in America. That will be
STFC-RAL-CR03 R61: pushing this limit down. The reason we have to go to America is they get more photons than we have. So does that mean they get more energy? So they're doing some
STFC-RAL-CR03 R61: much, much more energy than we have. So but what's the source of these gravitational waves? We're not. We're not specifying the source. We're saying that if that's a good question, because at the moment they shouldn't exist if they do exist. It means that there's physics beyond the standard language, sure.
STFC-RAL-CR03 R61: and that's what they're obviously leading to, I said, I'm glad you brought that up because it would lead to something beyond the standard model if someone observed them. So these are relatively cheap experiments to set up. They're not expensive in terms of particle. If you're building, say the next collider, these are relevant.
STFC-RAL-CR03 R61: 100 million would set you up with this archive.
STFC-RAL-CR03 R61: Oh, that that's an interesting yes, that's a an astrophysical measurement that people taking part of the cosmic microwave background in a frequency range
STFC-RAL-CR03 R61: that's different to the frequency range of the taking part in the cosmic microwave background, the high frequency part. And they've looked at changes to the the radio frequency
STFC-RAL-CR03 R61: due to gravitation wave to see if there's a signature.
STFC-RAL-CR03 R61: And that's a ground based experiment or yeah, no. Sorry. That's a satellite based. Yes.
STFC-RAL-CR03 R61: So finishing off. Now, I mentioned that photon photon, graviton photon.
STFC-RAL-CR03 R61: I've seen a photon. You're now elect to read plasma instability. They're all very similar. They all fall into the same kind of account. And here what I've got here is kind of 2 stream instability. I talked about a 2 stream instability of the electropositron being going through low density plasma. The same thing that can happen with neutrinos neutrinos moving through plasma.
STFC-RAL-CR03 R61: and moving close to the speed of light, will generate plasma waves also moving at speeds very close to the speed of light, and we think this could be due to the enormous heating of the supernova type 2 itself, so this could give rise to the explosive event. Now, before you say, the neutrinos don't interact with anything we're talking about
STFC-RAL-CR03 R61: huge boxes on the trees here. So the flux of neutrinos is basically 10 to the 2920, 10 to the 30 watts per square centimeter.
STFC-RAL-CR03 R61: and the density of the medium that they're moving through is about 10 to the 29 particles centimeters. So they're inside. They are very close to the protonut star of a supernova itself. So you can actually get
STFC-RAL-CR03 R61: an instability going on which is a 2 stream instability driven by a material being. And you can also get damping of particle waves, and this could be due to say the process called Landow damping.
STFC-RAL-CR03 R61: And we've assumed that this could be associated with the cooling of nutrient stars. So you've got nutrients neutrinos that are inside a dense volume of protonutrient material. And they're cooling that material by taking energy away from the plasma waves that we can normally associate with it.
STFC-RAL-CR03 R61: And the other instability we've got here is a light, weak, viable instability, and we've thought that this could be to this could produce. The static magnetic field may be responsible for the primordial magnetic field structure in the early universe. So
STFC-RAL-CR03 R61: you use the same kind of physics in this case. Here we're using the the Hamiltonian for the the neutrino. These are electron neutrinos, and they give rise to 2 forces. One is the force on the
STFC-RAL-CR03 R61: the materials due to the background electrons. So it's the gradient of the density of the electrons, and the other is force on the electron due to the gradient of density of the neutrons. So you get these combination of forces which actually help drive the instability. So these are very similar to the type of forces that you can generate in a plasma medium.
STFC-RAL-CR03 R61: And when we looked at the anomalous neutrino heating of neutrino problem, looking at 2 stability, we find that we can capture about one. To say point 1% of the neutrino energy that's coming out of a supernova in the material that's surrounding the stalled shock, and it could re-energize the shock. This is something that we're still working on. And there's a lot
STFC-RAL-CR03 R61: interesting science to be done there, the genome damping. What does that mean? That means that if you've got distribution of particles in this case, the distribution of electrons, the genomes are moving with phase velocity of d. 5. Close to the phase, velocity. Sorry. T.
STFC-RAL-CR03 R61: Close to the space velocity of the possible waves. They take energy away from the electrons, take it away from the pass wave by being accelerated. So these materials are being accelerated. If the base velocity, the velocity, is close to the base velocity of the electron wave.
STFC-RAL-CR03 R61: And I think between interactions have just summarize that very quickly, so they can generate some intense relativistic plasma waves by reducing instability, and they can be accelerated by plasma waves to higher energy, and they can be responsible, perhaps, for supernova explosions. Now.
STFC-RAL-CR03 R61: those those intensities of materials that we're using here are way beyond anything. So there's no, there's no hope of studying that in an experiment. But theoretically exactly last thing I said, that I just mentioned this. This is something that again Bill and I talked about a long time ago. I don't know radiation.
STFC-RAL-CR03 R61: and it's something I've just got 2 slides in this, and it's another experiment. No one really is aware.
STFC-RAL-CR03 R61: Oh,
STFC-RAL-CR03 R61: The possibility of doing this experiment using the lasers that we're building. This has been on the cards for a long time, and it's the equivalence principle that tells you that an accelerated particle would be exactly the same as a particle sitting in the field of a black hole, and so you'd see or expect to see, the equivalent hawking radiation which is given by this equation here hawking radiation
STFC-RAL-CR03 R61: temperature would be T is given by the acceleration due to the black hole
STFC-RAL-CR03 R61: exactly the same kind of relationship you've got for the unknown radiation, whereas the temperature of the radiation that the observer will see is given by the accelerated
STFC-RAL-CR03 R61: acceleration he's he or she is experiencing. So you've got this person here accelerating, and they're being accelerated by value A,
STFC-RAL-CR03 R61: and that would actually constitute, then, through the performance principle, a temperature they would see the temperature. Now, the problem is.
STFC-RAL-CR03 R61: is that possible to see? There's lots of people saying there's no such thing as under radiation. There's meetings on it. People discuss it a lot.
STFC-RAL-CR03 R61: But it's something that if you actually could determine whether or not there is a real possibility of looking at radiation, we could possibly do it with the high power lasers that we've got. So this is an image of what we're actually looking at here with 2 high power lasers with an electron beam going through. So these red regions here are high powered lasers. We are certainly polarized.
STFC-RAL-CR03 R61: We send an electron beam in the electro beam is moving in a circular orbit, and we are accelerating into the circular orbit, and they shoot. If hawking radiation does exist, they may be able to detect it by looking at the Green Wind Seal. So that's that's
STFC-RAL-CR03 R61: something that we've thought talked about for years and years, and still really don't have any further
STFC-RAL-CR03 R61: movement in this in. We'll get lots of papers going out, whether it's real, whether it's not real, whether we can see it.
STFC-RAL-CR03 R61: Who's not an accelerating film, etcetera. So there's lots of gr puzzles here that we have to
STFC-RAL-CR03 R61: understand. And so Conclusion said.
STFC-RAL-CR03 R61: places are closing in on the intensity frontier. You guys do the energy frontier. But I also admit that you can do the intensity frontier as well.
STFC-RAL-CR03 R61: New accelerators are being generated to take us to tens of Gev new compact, light sources, X-rays tera, and fundamentally using these lasers, is developing extremely quickly or extremely fast. Many people around the world are now working in this area. And it's opening up lots of
STFC-RAL-CR03 R61: new things, new ideas to study. So those are only a fraction of the things that are going on over at epic, or will be going on over at Epide.
STFC-RAL-CR03 R61: Hope that we can have a strong interaction with particle physics group here, because you guys know more about some of these problems than we do. So I'd like to stop there and thank you for your attention.
STFC-RAL-CR03 R61: Thank you very much for the nice overview. Let's go with questions.
STFC-RAL-CR03 R61: So just to comment on your last statement. Yes, what are the places where you see
STFC-RAL-CR03 R61: something we haven't done. There was an experiment that was done in slack a number of years ago. We could do it easier here with the 10 d. With a higher power basis. So there's lots of experiments that have been done
STFC-RAL-CR03 R61: in the past that you could redo with
STFC-RAL-CR03 R61: a new setup. And I think it's just a matter of getting together around the table and talking about forming collaborations. I mean, the collaboration that I'm involved with with Jack is is opening up. I mean, we've got a number of people who are
STFC-RAL-CR03 R61: in particle physics who are also involved. I mean, give you an example. You know, he's he's heavily involved in physics, and the work particularly. I see some of the students were working with us in
STFC-RAL-CR03 R61: theory, and also the inside.
STFC-RAL-CR03 R61: So I think that I think we've got your point now in
STFC-RAL-CR03 R61: fundamental physics where the laser people, the laser traditional people, we need your help now to tell us what experiments you'd be interested in.
STFC-RAL-CR03 R61: That's that's really what. Why, we're talking to you now.
STFC-RAL-CR03 R61: and I've always always talked to. But you like to build big colliders. Yes, and I think plasma accelerators can play a role there. We can build up a collider, perhaps in the future that may.
STFC-RAL-CR03 R61: People are working in that area. I mean, we're trying to generate
STFC-RAL-CR03 R61: plasma collider that will accelerate ones. And the lifetime of those point ones is quite large. In terms of that. They're being captured by another light, and we can actually, some experiments have been done accelerating points. But you're right with a collider. We could possibly do that. But the other
STFC-RAL-CR03 R61: problem we've got is, if you can get up to 500 G,
STFC-RAL-CR03 R61: we could probably use an afterburner
STFC-RAL-CR03 R61: by sending those beams into plasma to boost their energy up to a TV or beyond that. And those are proposals that are already out there. People have been talking about that.
STFC-RAL-CR03 R61: Think on the glider things and the white fields for the laptop.
STFC-RAL-CR03 R61: Nobody. May I please ask you to go back to this neutrino?
STFC-RAL-CR03 R61: I think. Sell your paper on it. That'd be easier. Which one are you able to?
STFC-RAL-CR03 R61: So I mean, yeah, just a are you able to have here.
STFC-RAL-CR03 R61: even even if you built them between a backdrop, the blocks would be too small. One of the things that must point out is the Msw. Effect
STFC-RAL-CR03 R61: is a plasma effect on the sun. So it couples to a plasma gradient.
STFC-RAL-CR03 R61: So if that gradient is a space time structure, in other words, it's a wave.
STFC-RAL-CR03 R61: you still get the same effect happening. So the neutrino will exchange momentum with that structure, and that's very similar to what I've been doing here. So what what I've done is, I've just taken the Msw. Formalism.
STFC-RAL-CR03 R61: Replace the density gradient with a moving structure that's got a space time so far.
STFC-RAL-CR03 R61: and that gives me the coupling. Then, between the neutreno and the possible way. But if you wanted to look at, say anything.
STFC-RAL-CR03 R61: see
STFC-RAL-CR03 R61: labor oscillation like an Msw. Thing, you would have to go, for you know the sun's density is 10 to 26. We can't produce that density, you know. You'd have to have the density of that over a million kilometers, and we can't do that.
STFC-RAL-CR03 R61: But you really, I mean, if it was possible you could see the Mst. Yesterday.
STFC-RAL-CR03 R61: and that would that be the key, because Msw. Couples into the. So all these things are very, very similar.
STFC-RAL-CR03 R61: There's not I think there was.
STFC-RAL-CR03 R61: I can give you the paper that points this out
STFC-RAL-CR03 R61: on the neutrino topic. Would you be able to see anything in the energy spectrum neutrinos from the Galactic Center?
STFC-RAL-CR03 R61: Yes, if you. If you have got. If you've got a spectral structure, you could be able to see if there's a component of it that is not thermal.
STFC-RAL-CR03 R61: and that would indicate that these particles, these materials, are being accelerated through some turbulent medium or cycle outlook.
STFC-RAL-CR03 R61: So so it's coming from a pristine source saying like that through through
STFC-RAL-CR03 R61: very turbulent, like the center of the galaxy. And if you see a shift in the spectrum, we discussed this a number of years ago with Bill and these guys. And it's something that we've got could be a possibility. But no one's got a neutrino detector that can do that yet
STFC-RAL-CR03 R61: that are coming online.
STFC-RAL-CR03 R61: Hopefully, they could give us that. But do they've only seen what? Is it? 19 materials that are, you know, outside the solar system that come from outside the solar system. And that came from Magnetic Cloud 1987, 8.
STFC-RAL-CR03 R61: So there's also well, there's ice cube. Yes, getting an upgrade. And then there are other proposals. There's another proposal for a big.
STFC-RAL-CR03 R61: including a protector in the Pacific.
STFC-RAL-CR03 R61: If we can get enough neutrinos, and you can see a spectrum. Then, if there's a shift in the spectrum. Yes, we should be able to identify some of these effects, particularly the neutrino.
STFC-RAL-CR03 R61: and I've been working in some of this for a long time. As you probably know, you haven't seen many coming from outside. The solar system is coming constantly as from nuclear reactors. Yeah.
STFC-RAL-CR03 R61: is it on zoom?
STFC-RAL-CR03 R61: Maybe I can ask one thing. I was wondering
STFC-RAL-CR03 R61: the applications in the lithography. I mean all the development that goes into the laser physics and protonics. And this applications. That's a big money game, is there? And I mean, okay, Ms, Asml and Z. And they are the drivers of that.
STFC-RAL-CR03 R61: Is there some role where you know from academics which you think can match that or complement that, or you know, somewhere, somewhere.
STFC-RAL-CR03 R61: I think. Generating a very, very X-ray sources. You know, we get a compact accelerator. We generate X-ray source, and I think that will lead to applications in that area. And Jack may be able to tell me more about that, since he's closer to the
STFC-RAL-CR03 R61: it's a practical application design.
STFC-RAL-CR03 R61: Yeah, I mean, there is already, you know, money coming comes in to various university groups from Asml and the like as well. It's not like they interact with the community in various different ways. So yeah, they do. Yeah, okay.
STFC-RAL-CR03 R61: I mean, I think what we're trying to do here is trying to get more interaction with you guys because we're building a very expensive we don't. I mean, we don't know as much of the fundamental physics. You guys.
STFC-RAL-CR03 R61: yeah, I think that sounds like a nice call for us.
STFC-RAL-CR03 R61: Think one- one thing, that
STFC-RAL-CR03 R61: myself, Norman, a few other people. We set up this small amount of money from the allowed us to interact
STFC-RAL-CR03 R61: in a sensible way when we threw money there. So we we held meetings, and we held quite small workshops and things like that. We would invite people to come. Talk about ideas. And a lot of these ideas were germinated.
STFC-RAL-CR03 R61: but the latest didn't exist, so no one could see doing anything now we're in the threshold that we need to do something.
STFC-RAL-CR03 R61: Folks mentioned the latest in the Uk. But they're also layers in Europe and in the Us that are kind of pushing similar
STFC-RAL-CR03 R61: levels of intensity, repetition rate, and so on. So it's it's not just here. It's pretty global
STFC-RAL-CR03 R61: excel or example.
STFC-RAL-CR03 R61: But that's a that's something that we need to work at. In fact, when we, when the design for a TV accelerator was put forward, we did work with
STFC-RAL-CR03 R61: practical physics, people. We had a strong interaction with people like who come here and tell us what they needed
STFC-RAL-CR03 R61: as a as the parameters where I'm afraid of
STFC-RAL-CR03 R61: think works very closely with people here working by enforcement.
STFC-RAL-CR03 R61: Okay, thanks
STFC-RAL-CR03 R61: it.
STFC-RAL-CR03 R61: That's funny.