Educators From Australia

"Four different types of particles: electrons, s, s and gold atoms. ...Can anyone suggest which one you can't put in a particle accelerator? ...A . Yep! Do you know why? Because it isn't charged. Thank you very much. ...[I]t doesn't have an ."

"Building up charge, actually building up , is the key to giving particles energy in a particle accelerator. ...Now some of the first particle accelerators were actually genuinely using this mechanism of having a belt and some rollers, and building up lots of voltage. They were called Van de Graaff accelerators. They still exist. I've worked on one... If they're the same charge, which get repelled, and there's force there, they're pushed away and they gain some energy... [I]n the case of an accelerator we'll get our particles... going faster and faster and faster toward the speed of light."

"The next thing we want to do with those particles is to give them some energy. That's the basics of how an accelerator works. I've got a machine here called a which does that..."

"Now there's another one... that might not have an electric charge... The gold atom, yes. Can anyone suggest a way to get that gold atom into a particle accelerator? ...You can ionize it. Thank you. So to ionize a gold atom you can rip the electrons off or add more electrons on... Give it an electric charge, and then we can put it into a particle accelerator. So that's the kind of particles we need."

"So my number two thing you probably shouldn't do with a particle accelerator. You probably shouldn't put your head in the beam... On this one I want to have... a vote... What might kill you first? ...Would your head freeze because of the ? It's at minus 271 degrees Celsius] in some accelerators... take the Large Hadron Collider for example. There the magnets are pretty cold, or would the heat from the beam make your head explode, or would your head explode from the , or would you die from the dose? ...I want a show of hands for which one you think would get you first."

"If you just put this beam onto a massive block of copper, you could actually melt 600 tons of copper from solid to liquid, just using the Large Hadron Collider beam."

"What I'm going to do is suck out all of the air out of this container and see what happens to marshmallow man, or indeed, what might happen to our pet bunny rabbit in a particle accelerator. ...Oh my gosh it's huge! That's amazing! Sorry, we haven't tested this. I didn't realize it was going to be this good. ...That's probably what would happen to your little bunny rabbit, but in a slightly more horrific fashion."

"Why couldn't you put your pet in a particle accelerator? ...It doesn't have an electric charge. ...He's slightly too big, and the other thing... he's going to be affected by the vacuum in the pipe of the machine..."

"It depends on which accelerator we're talking about, but let's consider the . ...It's minus 271 degrees. ...This is a picture of one of the 15m long s, one of the [beam] bending magnets in the machine... but it's extremely difficult to get your head in there. So... you wouldn't stick your head in the dipole. You'd stick it in somewhere easier... that wasn't cooled down to minus 271."

"So they had to put a lot of effort into designing... the , which is a massive long block of very dense , which absorbs the energy. But even then there's so much energy that they can't just dump it directly on it, or the would make the thing explode. So they actually have to paint the beam in... a swirly pattern... to spread out the load of the heat from the beam on this huge graphite block."

"So what about the heat from the beam? Well this is a challenge... [I]t's actually incredibly difficult to stop the beam, and if you put your head in front of the beam... it would actually go straight through and out the other side. In fact it has enough energy to go through your head and out the other side about 100,000 times before it loses all it's energy... [T]hat's actually one of the issues they had to deal with when designing the machine, is how do you stop the beam... [W]e want to stop it occasionally, intentionally..."

"What about the ? ...People have done studies in outer space of astronauts and how long they could survive in the vacuum... That information say that you can survive in outer space with your spacesuit open for about ten seconds before you're ripped apart by the vacuum. So I don't think that's going to get you first."

"[A]... Large Hadron Collider radiofrequency cavity... is one of the devices, and... operates at... superconducting temperature at 400 MHz... [T]his is one of the devices into which we pump a large amount of RF energy, send the particles through and as they go through, as you demonstrated very nicely, they gain a little bit of energy..."

"[I]n cancer therapy usually you like to direct a dose of radiation exactly where you'd like it, so in this case... a child with a spine that needs irradiating. They've had a tumor removed from the base of the skull and they need to irradiate the spine in order to stop the cancer spreading down the spine... With... usual X-ray radiotherapy the dose distribution there is the best that we can do using all modern techniques. You can see that underneath the spine in... the stomach area there is quite a lot of radiation dose that we might not want..."

"In the days of Cockroft and Walton, when they were first developing particle accelerators they didn't know about the dangers of radiation, and so one of the ways that they counted the events... what was happening in their experiments, was... to sit... under the beam. The beam would come down, some nuclear reaction would happen, and... his fluorescent screen... would light up every time what they were looking for happened... [T]hey would sit there and count each time it lit up, sitting underneath the beam, being irradiated. ...[T]hese people lived relatively healthy lives, and Cockroft and Walton got a for work, which doesn't justify it, but there have been people who have stuck their heads in particle accelerators."

"Nowadays you wouldn't want to do that voluntarily, and you wouldn't want to do it without understanding the consequences, but there are some situations that you might want to do it in... [T]here's a very good reason for that, because if you take a much lower energy beam that the Large Hadron Collider beam, and you put it into water, or into the human body, or into tissue and you start it with the correct amount of energy, it will actually slow down and stop, and deposit almost all of its dose (or its energy) in one spot... [W]e call this the ."

"So it sounded like a crazy question, but if you had a brain tumor you might very well want to stick your head in the beam of a particle accelerator."

"If you use protons instead you can... get a much better defined distribution of the dose and this is really a fantastic treatment. It is more expensive than x-ray radiotherapy, but based on the basic physics of how a beam reacts inside... the body, or inside tissue... it's a fantastic treatment, and one that we should look forward to using in the future."

"People in the U.S. did think about building a particle accelerator (a neutral beam accelerator) that they would launch into space... and then they would use it to shoot down satellites and... missiles and destroy anything that they didn't like, because they were going to have this super powerful beam in space."

"Number three. Don't use a particle accelerator as a death ray. When I was putting together this lecture I asked... my very esteemed colleagues, "Has anyone ever tried to develop an accelerator as a weapon?" And they said, "Oh mumble, mumble cold war, space, Star Wars something or other... No" That was their conclusion... They were wrong."

"What could you do... if you took particle accelerators, and you made them really powerful... [T]his is something that I work on, is taking proton accelerators of relatively low energy, but putting more and more particles in, and getting a really high beam power..."

"They developed this machine which was only about this big [~1 meter] and they used ultra-lightweight materials, and it only weighed about 50 kg. So compare that with a 27 kilometer long ring. ...It was only low energy but they... sent it up in a rocket and they actually tested it in space and brought it back down... and they tested it again on earth, and it still worked, which I think is an incredible feat of engineering... [P]eople really haven't heard of this experiment... It's called the BEAR (Beam Experiments Aboard a Rocket) project in 1989, and I have a contact who worked on it..."

"[T]his is called the Standard Model Lagrangian, that curly \mathcal{L} at the start is for Lagrangian... and there's lots of different components of that. Now if I write it out in full, I get what is the most egotistical physics teacher in the entire world. So if I wrote it out in full... really you don't need to read it, I promise, all of the different terms in that equation describe an interaction between different types of particles and force carriers..."

"[Y]ou may have seen... when the LHC was in the news, diagrams that look a little bit like this. These are called s after the famous physicist, Richard Feynman... [W]hat... most of my colleagues in particle physics do, is they take this [full Standard Model] equation, they figure out which particle's interacting and how: what's coming in, what coming out. They do twenty-one pages of calculations, and they come out with a number that is the probability of that interaction happening... [D]epending on which particles go in, you choose a different term that corresponds to those, and which particle comes out, you choose a different term that corresponds to those. Turn the handle and you get your result out the other end. I just taught you quantum field theory in about 2 seconds."

"I want to go back to about the late 1920s and 1930s when a new type of was invented, called the . These are still in operation today, but the original ones... This is a patent from... and this is 2 Ds as we call them... electrical cavities which would sit inside a whopping great ... [W]e start in the center with some particles, and they always have to be charged particles. So either electrons, s... s, charged atoms. Things like that, and we give them a bit of a kick, because there is a voltage between these two [Ds] halves, and each time the particle moves between those two halves they get a little bit of a kick, a little bit of energy. Now because they're sitting in a whopping great magnetic field, the effect... that has on a charged particle is to actually bend it around a corner. So it bends around a corner and it comes back again crossing this gap, gaining a little bit more energy and... as it continues to gain energy it spirals out... So the limit in the energy in this machine is mostly how big you can build your magnet, and how much iron you're willing to afford. Now this really was the original type of... high energy particle accelerator, and this is a photograph of Ernest Lawrence and his student Milton Stanley Livingston, who I should say, actually built the thing... [T]his machine got up to about 1 million s."

"So we can't use it as a weapon. ...No deployed weapon has ever used this technology."

"In physics I use this energy range of s which means the energy an electron would gain if I put it through a potential of 1 . So MeV is million electronvolts. And that's the scale of that... [cyclotron] they're standing next to..."

"So we still use a few cyclotrons, but most of the machines that people talk about, especially in the media, are a different type of machine which we call a , and we have two of these types of machines at the Rutherford lab at Harwell. One is the ISIS Neutron Source that I'm associated with, and there's also the ..."

"Radiation effects. ...There's this guy, , who... before the days of such strict health and safety, somehow managed to bypass a safety mechanism on an accelerator, and stick his head in a 76 GeV proton beam. Now that's quite a lot lower than the Large Hadron Collider beam, but the amazing thing is that he just saw a really bright flash, and he didn't feel any pain at all... Most people think, "Well, this beam, it's got lots of energy. It will just destroy you" but actually that's not quite what happened. ...[A]fter it happened his face swelled right up and the skin on that side pealed off, but he didn't die. ...[H]e went on to get his PhD and... he worked as a scientist for many years... [H]e's actally still alive in Russia, living in relative obscurity. ...A journalist interviewed him few years ago and... because the side of his face that the beam irradiated was paralyzed... and he hasn't been able to move the skin on that side of his face for so many years. That side of his face like it was... the day that this accident occurred. When I... read this, I was like, "Miracle cure for aging!" Yea, paralyzed face is probably not a miracle cure..."

"What is a particle accelerator? ...This is the ...the world's biggest particle accelerator. It's 27 kilometers in circumference ...buried about 100 meters underground between the borders of France and Switzerland, near Geneva."

"So there's some really interesting applications of accelerators, way outside of the realm of particle physics, that we're starting to get a handle on."

"A lot of s' food is irradiated before they send it up so that they... aren't going to get sick from it."

"The only problem is [that] the accelerator for this is about 10 times more powerful... than we can currently make. So there's lots of challenges for people like me who design accelerators, to try and come up with ways of making them more and more powerful, for very good reason."

"Five years earlier... [a]s my eyes adjusted to the darkness, the true wonder of this designated "dark sky site" revealed itself. ...The stars and planets weren't up there and I wasn't down here: it was all part of one enormous physical system called the Universe. I was a part of it too. ...I'd never really felt my place in it until that moment."

"[A]s I studied more physics the question... at the core... was: "What is matter, and how does it interact to create everything around us—including ourselves?""

"I suppose I was trying to figure out the meaning of my own existence. ...I went about it in a more indirect way: I set about trying to understand the entire Universe."

"There's this guy called Monsier Mangetout... a Frenchman who, according to Wikipedia ate all of these crazy things. Even he, though, wouldn't eat a particle accelerator because parts of the machine become radioactive, and while he seems to be fairly stupid, given the things he ate, even he wouldn't go that far."

"The interesting thing about radiation is it is naturally present in most of the things around us. ...How many bananas do you think you'd have to eat to get a dose of radiation that would make you sick? ...It's the in the bananas. ...A very small percentage of the potassium is naturally radioactive, but you... have to eat five million... in one sitting to get sick..."

"So what is ? It's energy in the form of moving particles or waves, emitted by an atom or another body as it changes from one energy state to another. That's the official definition."

"[Y]ou can have two... main types of radiation, which are ionizing, or non-ionizing."

"This thing... is a , and it will tell us whether these things are radioactive. ...There is something coming off [clicking noise from the thoriated rods] there. Just to demonstrate that the bananas are really only mildly radioactive, we can't pick them up with a Geiger counter. It's really is very mild."

"That thing... is radioactive. They're called thoriated rods, and they're used in welding. You can... just buy them."

"There are foods which are naturally radioactive, but most of us would like to think we've never eaten food that actually been in a particle accelerator. ...That sounds a bit crazy. ...In the UK we don't eat many things that have in a particle accelerator but things like herbs and spices, and some other things occasionally go through a process called cold pasteurization, electronic pasteurization, which uses electrons from a to treat the food. ...It is legal in the UK and in the EU, and it's fully authorized... [T]here's a number of foods... which have been irradiated, or could have been irradiated, and that goes... from bananas, sometimes... to slow down the ripening process... so they have a longer shelf life... [A]s you increase the amount of radiation that these things are treated with... from some grains, seafood to kill bacteria, herbs and spices are a more common one, and then even sometimes higher doses on things like poultry, to kill ."

"So when we're thinking about radiation and radioactivity, it is worth keeping in mind that just the fact that something is radioactive does not means it's harmful..."

"I'll tell you very briefly how they work. ...The first thing we need is some ...s, or even atoms themselves perhaps."

"I have a demonstration... which is the simplest particle accelerator I could make.... in a giant salad bowl. ...[W]hen it goes over the charged strip it picks up the same charge and it gets repelled ...then it hits the grounded strip and it dumps all of that charge, but it keeps its momentum, it keeps rolling around ...So every time it goes over one of those four [repelling] strips ....it gets a kick, or gets accelerated and it gains energy again and again. ...In this demonstration, the ball has to change charge, and fundamental particles don't change charge, so in this case my voltage in constant and the ...[ball] changes charge, in a real accelerator we have a constant charged particle, and that means we have to change the voltage."

"So the final thing that you probably shouldn't do with a particle accelerator is: You probably shouldn't destroy the Earth with it. ...People seem to think that when we design new massive particle accelerators that are going to have particles that are huge energies that we've never created before in the lab, that somehow... we just built it for the lulls, and then we're going to destroy the earth with it, and that we haven't quite thought it through, and that we're not quite sure what we're doing... If you're at all concerned, please go to HasTheLargeHadronColliderDestroyedTheWorldYet.com and... you can tell me what you find there."

"In answer to some of the questions that we had a few years ago when the Large Hadron Collider started up... "Could it destroy the world?" ...The most convincing answer to me as to why it couldn't, is because we have particles in outer space from cosmic rays and things like that, at much much higher energies than we could ever dream of creating in the lab. And so far they haven't done anything catastrophic to us and we're perfectly fine. So in terms of just reaching a higher and higher energy... it doesn't really matter what we do in the lab. We should be safe on earth from these high energy particles."

"That's only one particle accelerator. There are actually over 26,000 of them in the world."

"In this book, I will take you through twelve key experiments that marked... a discovery... we now see as essential to our understanding of the world... [T]hese experiments embody the spirit of enquiry that stems from human curiosity. ...[T]hey have changed our lives in almost every aspect, from computing to medicine, from energy to communications and from art to archaeology."