1 00:00:01,480 --> 00:00:16,620 So. So it is wonderful. 2 00:00:16,640 --> 00:00:21,350 All of it says it's a great pleasure to do these things, but in this case, it really is. 3 00:00:22,390 --> 00:00:29,240 Um, I first met Don in 1975 when I came here as a graduate student. 4 00:00:29,870 --> 00:00:38,150 Um, and one has some heroes, uh, from whom one learns in particle physics, and there are not very many. 5 00:00:38,840 --> 00:00:45,739 Um, Don was certainly one of them, uh, other people being Roger. 6 00:00:45,740 --> 00:00:53,149 I'm sure I'll spare his blushes by saying so, um, and, uh, going to Wolf and, uh, beyond Vic a Daisy. 7 00:00:53,150 --> 00:00:58,910 So Don was one of my very few experimental heroes in particle physics. 8 00:00:58,910 --> 00:01:05,270 So when, uh, John Ritter asked me, uh, when the university were naming statutory chairs, uh, 9 00:01:05,270 --> 00:01:11,390 whom I would like my chair to be named after, it took me about a microsecond to decide on Don. 10 00:01:11,750 --> 00:01:16,459 Um, and so it's been my great privilege and pleasure to be the first Donald H. 11 00:01:16,460 --> 00:01:21,080 Perkins professor, uh, of experimental physics. Although I'm now emeritus. 12 00:01:21,080 --> 00:01:28,520 They tell me, which means they've stopped paying me if I like. And so, um, so, um, I should give a lot of credit. 13 00:01:28,520 --> 00:01:37,490 And thanks, uh, to Don's daughters who are here, uh, because they've given me a lot of information which I wouldn't have been able to find otherwise. 14 00:01:38,030 --> 00:01:41,210 Um. Uh, so be sure. Have. Michelle. Thank you very much. 15 00:01:41,990 --> 00:01:47,660 Uh, so this is Don's career in a nutshell. Don't really be talking about this time. 16 00:01:47,720 --> 00:01:55,430 Of course, there's much more to come, but that's will you will see all of those things, uh, in the next, uh, lectures. 17 00:01:56,510 --> 00:02:01,400 Um, so basically he was born, uh, in 1925, in Hull. 18 00:02:02,300 --> 00:02:08,750 Um, so that's telling you something about about that, uh, Don's father and mother were both schoolteachers. 19 00:02:09,410 --> 00:02:13,970 Uh, and this is his school, um, which had been founded not long before. 20 00:02:14,240 --> 00:02:17,390 Uh, he attended it, actually. So he must have been one of the first pupils. 21 00:02:18,080 --> 00:02:21,170 Uh, it was a grammar school in those days. Uh, in 1932. 22 00:02:21,170 --> 00:02:26,620 It was a tough school. Um, so Don no doubt held his own. 23 00:02:27,310 --> 00:02:37,210 Certainly he flourished academically. Um, he had many extracurricular activities, and the first one was his first publication at the age of 12. 24 00:02:38,440 --> 00:02:43,720 In the McConnell magazine. Now, in most audiences, I would have to explain what McConnell was. 25 00:02:44,860 --> 00:02:50,620 Uh, but in this audience, I'm sure at least all of the the boys will remember McConnell. 26 00:02:51,460 --> 00:02:58,210 Um, uh, even I remember McConnell. I wasn't very good at it, but Don was, uh, was an absolute whiz. 27 00:02:58,780 --> 00:03:02,560 Uh, this is his first publication with a very tiny differential gear. 28 00:03:02,980 --> 00:03:09,190 Uh, I was in a car engine. Uh, so this was supposed to be the smallest one that anybody had come up with, which is pretty impressive. 29 00:03:10,000 --> 00:03:13,840 Um, so that was when he was 12. So that was 1930? 30 00:03:14,200 --> 00:03:20,610 Uh, seven. Then you have the second publication in Makana magazine, and this one is even more impressive. 31 00:03:20,630 --> 00:03:27,020 This one is a an aircraft locator apparatus. Um, and this one was published when he was 16. 32 00:03:27,530 --> 00:03:31,340 Um, also at the age of 16, he was building radios. 33 00:03:31,400 --> 00:03:37,470 Uh, and he built a crystal radio receiver, uh, and he apparently the first transmissions he picked up, 34 00:03:37,560 --> 00:03:42,620 it says in one of his articles was some news about Converse's experiment in Rome. 35 00:03:42,620 --> 00:03:49,249 I find it quite hard to believe that there would be a radio broadcast on Converse's experiments in Rome. 36 00:03:49,250 --> 00:03:53,120 But anyway, that's what Don says in his book. But certainly he built this radio. 37 00:03:53,180 --> 00:04:00,590 Um, so he was clearly a person who was extremely practical, very good with his hands and extremely, uh, inventive. 38 00:04:01,720 --> 00:04:08,480 Um. He also mentioned using his uncle's collection of moths and butterflies, which eventually ended up, uh, and whole museum. 39 00:04:08,500 --> 00:04:13,030 I would not have thought of him as Lepidoptera, but there you are. You learn something every day. 40 00:04:14,100 --> 00:04:17,610 Um. He left school in 1943 and had an excellent school report. 41 00:04:17,640 --> 00:04:21,660 Here is a report. I won't read it to you, but perhaps one extract. 42 00:04:22,260 --> 00:04:27,389 Um. He has a remarkable grasp of essentials and very considerable practical ability. 43 00:04:27,390 --> 00:04:33,480 Not be afraid of hard work. And earlier on, he says, uh, he obtained an open exhibition at Cambridge. 44 00:04:33,960 --> 00:04:39,660 And this performance did not surprise us, as Perkins was clearly one of the best students in school as hard. 45 00:04:41,070 --> 00:04:47,670 Uh, he had an offer to go to Trinity, Cambridge, uh, where he hoped to take a science degree and then study medicine. 46 00:04:48,270 --> 00:04:51,480 But he was screwed by the fact that he didn't have the requisite Latin. 47 00:04:51,510 --> 00:04:57,090 You can tell this was a new grammar school, because in those days, everybody did Latin, I did Latin. 48 00:04:57,720 --> 00:05:05,790 Uh, so this school kid, he was advanced and didn't bother with Latin, so he didn't have any Latin at all, and therefore he couldn't go to Cambridge. 49 00:05:05,790 --> 00:05:13,800 So instead he went to Imperial. Uh, and a friend of his from Yorkshire had already gone there and clearly given him the idea that it was all right. 50 00:05:14,190 --> 00:05:22,290 So in 1945 he graduated with a BSc with first class honours, uh, sufficiently high up that he qualified for postgraduate scholarship. 51 00:05:22,830 --> 00:05:31,020 Uh, and then he registered for a PhD at Imperial. Now, most people's, uh, PhDs, you would pass over very quickly. 52 00:05:31,020 --> 00:05:34,350 You certainly pass mine over very quickly in a life story. 53 00:05:35,010 --> 00:05:38,310 But Don's, it turns out, was quite, quite remarkable. 54 00:05:38,560 --> 00:05:44,310 Um, and so I actually spend most of my time on Don's PhD thesis on the work, which was around it. 55 00:05:46,750 --> 00:05:50,440 So you first have to put yourself into his intellectual milieu. 56 00:05:51,430 --> 00:06:00,700 Um. And then when Don began his research work, the only particles we knew about were the proton, the neutron, the electron positron, and the muon. 57 00:06:01,850 --> 00:06:06,700 The muon was not really understood. As you'll see, that's part of the story. 58 00:06:07,030 --> 00:06:10,840 But anyway, it was known that there was a particle which was heavier than the electron. 59 00:06:11,800 --> 00:06:15,970 Uh, charged particle. Uh, so nobody had an idea what the muon was. 60 00:06:16,000 --> 00:06:21,160 Everybody thought a neutrino existed, but it wasn't found experimentally, of course, until much, much later. 61 00:06:22,300 --> 00:06:31,780 There was a postulation by Yukawa in 1935 that there was a carrier for the strong nuclear force, and that eventually became known as the pion. 62 00:06:32,330 --> 00:06:35,680 Uh, and it should be the lightest, stable, strongly interacting particle. 63 00:06:35,690 --> 00:06:41,799 And today, of course, it's produced by the million, uh, in modern experiments, not the experiment. 64 00:06:41,800 --> 00:06:47,920 But here's an example of a heavy ion collision, uh, at Rick, which almost every one of those trucks is a pion. 65 00:06:48,790 --> 00:06:53,530 But when Don started work, nobody had seen any trucks, uh, of a pion. 66 00:06:55,020 --> 00:06:58,860 Um. So what Dylan decided to work on were emotions. 67 00:06:58,860 --> 00:07:01,860 And I'll tell you a little bit about that in his own words in a moment. 68 00:07:02,430 --> 00:07:05,010 Uh, they go back. Right back to the dawn of particle physics. 69 00:07:05,100 --> 00:07:14,440 Um, so in 1895, when Cohen, uh, purely by chance, discovered x rays and use the photograph to, uh, see what they could do. 70 00:07:14,460 --> 00:07:18,780 That's his wife's, um, the famous photograph. Uh, from his laboratory. 71 00:07:18,780 --> 00:07:28,430 And another serendipitous, uh, use of photography and emotions was Becquerel, who, um, one day rushing off to some committee meeting, uh, 72 00:07:28,440 --> 00:07:36,330 put all of his equipment to look at, uh, phosphorescence in a drawer, one on top of the other, higgledy piggledy, including his photographic plates. 73 00:07:36,990 --> 00:07:41,700 Um, when he came to do an experiment the following day and, uh, and developed them, 74 00:07:41,700 --> 00:07:50,220 he found this incredibly bizarre black area when he dropped the whole thing in black material and put it in a darkened drawer. 75 00:07:50,640 --> 00:07:55,500 So he knew it wasn't light, but something was being emitted from this, uh, mineral sample. 76 00:07:55,500 --> 00:08:01,650 And when he looked at the shape of the blackened area and compared it to the minerals he'd placed on top of the, 77 00:08:01,680 --> 00:08:07,049 uh, photographic film, he could tell that this was coming from pitchblende and all of uranium. 78 00:08:07,050 --> 00:08:14,580 So this was the discovery of radioactivity, which in many ways, including, uh, X-rays began the study of particle physics. 79 00:08:14,580 --> 00:08:21,690 So emotions go all the way back. Don Supervisor was another great figure, uh, in particle physics. 80 00:08:21,690 --> 00:08:24,920 So he had, uh, uh, to the founders. 81 00:08:24,930 --> 00:08:27,210 Now we go on to J.J. Thompson. 82 00:08:27,810 --> 00:08:34,200 Uh, so the famous particle physics joke is that J.J. Thomson got the Nobel Prize for proving the electron was a particle, 83 00:08:34,200 --> 00:08:38,160 and his son got the Nobel Prize for proving the electron was a wave. 84 00:08:38,700 --> 00:08:42,570 And I was raised as a laugh among physicists, even if not the rest of the audience. 85 00:08:43,410 --> 00:08:47,970 Uh, so here are the two people in question, J.J. on my left. 86 00:08:48,540 --> 00:08:52,380 On the left as well. Um, and there is his son, GH. 87 00:08:53,070 --> 00:09:00,570 He was always called GH. There he is. When Don knew him as, uh, a great, uh, physicist at Imperial College. 88 00:09:02,100 --> 00:09:08,490 Um, so here is Don himself talking, um, about how he began, uh, life. 89 00:09:09,490 --> 00:09:13,730 As a physicist. The reason I got involved. 90 00:09:14,240 --> 00:09:24,500 I was a dick through college. I started research 3945 on the web. 91 00:09:24,920 --> 00:09:28,430 I can read after I read that article. 92 00:09:29,090 --> 00:09:37,100 Um, the quotes from. I have to read this section right in front of them. 93 00:09:37,430 --> 00:09:45,530 This is the time, the study of culture, possibly reminding you of a long time to go through the motions. 94 00:09:46,160 --> 00:09:49,910 Now, most of the experiments on the doctoral. 95 00:09:53,840 --> 00:10:06,580 And so I went to the my supervisor GP Tom Phillips on the JJ and I said that in long gone on to do cosmic rays and he actually sent me off. 96 00:10:06,620 --> 00:10:10,800 The first paper I read was the paper in German by blah blah. 97 00:10:13,040 --> 00:10:19,910 And. He said, come back when you read this paper and tell me exactly what you to do. 98 00:10:20,930 --> 00:10:23,240 So I was like, well, I realise that I have to. 99 00:10:23,600 --> 00:10:32,960 Well, you could get him off his high Nazi island by going to mountains or flying balloons or going to aircraft. 100 00:10:33,800 --> 00:10:38,070 And so I thought, well, this is a chance to get up. 101 00:10:38,120 --> 00:10:44,880 Always had a wish to get to the Andes. So I went to GP and I said, yes, I decide what to do. 102 00:10:44,920 --> 00:10:48,470 I'd like to do some exposures on that circle time. Bolivia. 103 00:10:49,250 --> 00:10:53,470 And he went back to the Buddhist. We have very little money. 104 00:10:54,160 --> 00:11:01,060 If you think I'm going to spend money sending research, you just want to go to the top of the market, you're going. 105 00:11:01,540 --> 00:11:04,780 He said. So I said, what do you suggest I do? 106 00:11:05,830 --> 00:11:09,050 He said, well, it's pretty obvious, but since you don't know, I'll tell you. 107 00:11:09,070 --> 00:11:14,160 You walk down exhibition mode to South County, the underground station. 108 00:11:14,160 --> 00:11:19,840 Now you'll find a bookshop, and in the bookshop you can buy or sell from across Europe. 109 00:11:20,650 --> 00:11:23,830 Look at the Atlas and select an out. And don't worry me anymore. 110 00:11:25,490 --> 00:11:31,730 I went down. I didn't buy here. Listen, I. Primates and Carpathians in the Alps. 111 00:11:32,300 --> 00:11:38,510 And I found finally a place where you can get up to 10,000ft for any effort. 112 00:11:38,600 --> 00:11:44,420 There was a railway all the way up, and that was the trial. I'll talk to you about it that way. 113 00:11:45,140 --> 00:11:49,220 Well, that was how I got through. Hopefully. Careers and emotions. 114 00:11:52,380 --> 00:11:56,190 So I'll, in fact, talk to you a little bit about, uh, the crow yoke. 115 00:11:57,060 --> 00:12:03,780 Um, so that was Don, uh, his lecturing style, which all of you will remember, uh, with great affection. 116 00:12:04,410 --> 00:12:10,800 Um, always entertaining, um, and almost always full of information. 117 00:12:11,670 --> 00:12:18,330 Uh, the reason. So, um, let's take ourselves back to end on, uh, began work. 118 00:12:19,470 --> 00:12:26,490 I'm 1947 is, uh, a remarkable year. Um, it turned out that 1896, uh, 119 00:12:26,520 --> 00:12:34,350 five and six were the separation between the discovery of X-rays and the discovery of radioactivity was about three months. 120 00:12:35,220 --> 00:12:41,850 Um, which is remarkable. Uh, so in 1947, another remarkable set of things happened. 121 00:12:42,530 --> 00:12:47,640 Um, so I remember I mentioned that the Yukawa particle had been postulated in the 30s. 122 00:12:48,120 --> 00:12:50,610 Um, but nobody knew quite what was going on. 123 00:12:51,150 --> 00:12:56,970 It turned out that, um, uh, there were various particles you could see in cosmic rays, which penetrated down to the Earth. 124 00:12:57,630 --> 00:13:05,550 Um, but they have peculiar properties that no one understood that decayed almost completely, never interacted with matter. 125 00:13:06,360 --> 00:13:10,490 Um, and so clearly, they didn't seem to have the right properties to be the Yukawa particle. 126 00:13:10,500 --> 00:13:14,070 So it was a cartoon, in a way, in, uh, the November of 46. 127 00:13:14,670 --> 00:13:18,230 Uh, came up with the two meson hypothesis that there were two different particles. 128 00:13:18,240 --> 00:13:23,130 One was the strongly interacting particle, uh, the pi that became pion, 129 00:13:23,610 --> 00:13:27,090 and the other was a weakly interacting particle, which later became known as the muon. 130 00:13:27,870 --> 00:13:33,600 Uh, that was published in a, uh, Japanese journal and was unknown in the West for at least a year. 131 00:13:34,380 --> 00:13:37,750 Um, uh, Don certainly knew nothing whatever about it. 132 00:13:37,770 --> 00:13:41,400 You see, the next paper is one of his, and we'll talk about that in a second. 133 00:13:42,240 --> 00:13:49,230 Uh, at the same time in Italy. And this is the, the, the statement he made about, um, looking at, uh, uh, 134 00:13:49,920 --> 00:13:54,090 hearing a radio broadcast when he was young, of the beginnings of this experiment. 135 00:13:54,660 --> 00:13:58,740 They were looking at cosmic ray particles, uh, which came down to sea level. 136 00:13:59,310 --> 00:14:04,139 Um, and what they saw was that all of these particles, the negative ones, just, uh, 137 00:14:04,140 --> 00:14:07,920 stopped in the carbon and decayed into something else, and nothing ever happened. 138 00:14:07,920 --> 00:14:12,210 There were no gamma rays. There was nothing to indicate any nuclear reactions. 139 00:14:13,560 --> 00:14:18,180 Um, then. Okay, the Indian Powell saw six particles, like the one that Donald seen. 140 00:14:18,810 --> 00:14:22,650 Um, and then in 1947, the discovery of the pion took place. 141 00:14:22,740 --> 00:14:26,280 Um, as we'll talk about, uh, now, in fact. 142 00:14:26,910 --> 00:14:34,200 So this is, um, in fact, uh, the, uh, first of Don's, uh, discoveries. 143 00:14:34,410 --> 00:14:41,940 Um, so as he mentioned, um, uh, G.P. Thompson arranged for him, uh, to take, uh, flights from the area. 144 00:14:41,940 --> 00:14:51,030 If, in fact, Don thought for many years that it was his persuasive powers that it allowed, uh, his, um, flights to be taken up in that craft. 145 00:14:51,390 --> 00:14:56,130 But of course it wasn't. It was GP who rang up RAF Benson and asked them. 146 00:14:56,640 --> 00:15:01,620 Uh, to allow Perkins to to take these emotions up, uh, to 35,000ft. 147 00:15:01,620 --> 00:15:05,400 And they flew around for several hours in Spitfires, apparently, which was been quite exciting. 148 00:15:05,880 --> 00:15:11,450 35,000ft. Um, and here is a photograph of Don. 149 00:15:11,460 --> 00:15:14,510 Uh, I'm at a loss to understand quite when this was it. 150 00:15:15,090 --> 00:15:22,440 This one, unusually, has on the back of date, but it's extremely difficult to read, and it looks like it says 1940. 151 00:15:23,160 --> 00:15:27,180 But he would have been 15 then. He should. He wouldn't have been smoking a pipe at the age of 50. 152 00:15:28,410 --> 00:15:33,810 But he's clearly a very young Don, so I suspect it was when he first went to Imperial. 153 00:15:34,530 --> 00:15:38,970 Um, uh, so anyway, there he is, looking very, very dapper. 154 00:15:39,780 --> 00:15:45,180 Um, so so yes, they, uh, flew these things, and then Don developed the emotion. 155 00:15:45,210 --> 00:15:49,280 Uh, and he found this remarkable event, which we'll look at in a bit of detail here. 156 00:15:49,290 --> 00:15:54,830 This is the paper on the right hand side published in nature in 1947. 157 00:15:54,840 --> 00:16:00,620 He did this in December of, uh, 46. Um, so this is Don's event. 158 00:16:00,630 --> 00:16:03,810 It's a remarkable thing. On the right, you see the photo micrograph? 159 00:16:04,050 --> 00:16:07,530 In fact, there's a photograph of this in Don's thesis. 160 00:16:07,530 --> 00:16:13,410 But it's so faded now that you can't see anything except the trucks B and C. 161 00:16:14,190 --> 00:16:20,579 Um, so what happens is that truck A is, in fact, um, what later became realised to be the pion. 162 00:16:20,580 --> 00:16:22,440 It comes in, it slows down. 163 00:16:22,440 --> 00:16:31,140 You can see it's slowing down because the number of, uh, the grains on the emotion that have been, uh, excited gets denser. 164 00:16:31,770 --> 00:16:34,860 Uh, and then it actually is captured by a nucleus. 165 00:16:34,860 --> 00:16:42,720 And that nucleus decays into a number of protons. Uh, so B, C, and D are coming out of the nucleus, C is going down into the, into the screen. 166 00:16:43,110 --> 00:16:50,790 Uh, b and D, uh, going out of the nucleus, you can see that slowing down because again the grain density gets um, it gets uh, more dense. 167 00:16:51,510 --> 00:17:01,320 Um, so a is something new. It's something which slows down and stops and then is absorbed by nucleus and causes it to, uh, to, uh, disintegrate. 168 00:17:01,950 --> 00:17:09,299 Uh, so Don had no idea what it was and now did anybody else for a long time, um, until in 1946. 169 00:17:09,300 --> 00:17:16,890 Okay. Then Ian Powell, who had much better quality emotions, uh, than Don had, were able to obtain two, 170 00:17:16,920 --> 00:17:23,400 uh, of these, um, uh, uh, uh, events, um, after the explosion at the Peak Committee. 171 00:17:24,720 --> 00:17:29,490 Um, and what you see, um, on the, uh, both the first one and on. 172 00:17:30,870 --> 00:17:38,270 Yeah, on this one here is that there's a muon, uh, a pion coming in here, which then decays. 173 00:17:38,280 --> 00:17:43,440 You can see again that the density of bubbles is getting of, uh, grains is getting heavier and heavier as it slows down. 174 00:17:43,950 --> 00:17:49,020 And then this one, uh, is emitted here. And the same thing happens here with a different angle. 175 00:17:49,620 --> 00:17:53,760 Um, and what you do in when you're analysing these places, you count the number of um, 176 00:17:53,900 --> 00:18:00,030 uh, uh, emotion, um, lobes per centimetre, which is proportional to the energy. 177 00:18:00,030 --> 00:18:03,510 And you look at the scattering which tells you something about the momentum. 178 00:18:04,020 --> 00:18:10,200 Um, uh, and then you can work out in principle, um, from Einsteins equations, you can work out the mass. 179 00:18:10,200 --> 00:18:19,770 And so they could work out that this thing was a mass, which was, um, around, uh, 140, uh, MeV, and that was a new particle. 180 00:18:20,160 --> 00:18:26,790 And that was published in nature, um, shortly after John's publication, as we saw in that list of publications earlier on. 181 00:18:27,510 --> 00:18:34,440 So this was the discovery of the pion. And, uh, eventually in 1950, uh, Powell got the Nobel Prize for that. 182 00:18:34,440 --> 00:18:42,210 In fact, Don, it also got an event like this, um, which he published in his thesis, um, from plates which were exposed for him. 183 00:18:42,660 --> 00:18:48,870 Uh shamone. By the way, the wrong guy. Another great, uh, cosmic ray person of the time. 184 00:18:49,650 --> 00:18:52,830 Um, and here is the picture in Don's thesis. 185 00:18:52,920 --> 00:18:59,610 Um, and again, you see this pattern that the muon comes in here and slows down and stops and decays into another particle, 186 00:18:59,640 --> 00:19:05,430 which turns out, uh, it's a muon. So, um, this was the third pion which had ever been seen. 187 00:19:06,120 --> 00:19:10,679 Um, but Don didn't bother to publish it because he was so impressed with the Bristol 188 00:19:10,680 --> 00:19:14,909 results from Mceleney and Powell that he thought they didn't need any confirmation. 189 00:19:14,910 --> 00:19:22,140 So all he did was put in his thesis, you know, is the third pion have been seen, but he never bothered to publish it. 190 00:19:24,060 --> 00:19:27,270 Those were the days. Um. 191 00:19:28,990 --> 00:19:33,040 He did put in his thesis, as I said. Um, so. 192 00:19:34,330 --> 00:19:38,260 That was Don's thesis. And the remarkable thing it was. 193 00:19:40,980 --> 00:19:45,450 Um, even as a graduate student, he was already at the centre of affairs. 194 00:19:46,290 --> 00:19:49,290 This is from one of his papers describing the situation at the time. 195 00:19:49,300 --> 00:19:53,230 Let me just read it to you. At the other end of Europe, in England, a by-product of the war, 196 00:19:53,230 --> 00:19:58,590 a nuclear program was the setting up in 1946 of a panel by the Ministry of Supply to 197 00:19:58,590 --> 00:20:03,450 oversee the development of special photographic emotions to record nuclear particles. 198 00:20:03,480 --> 00:20:07,920 Those were the days when government thought that nuclear physics and particle physics was useful. 199 00:20:08,700 --> 00:20:15,839 The chair was Joseph Rothblatt, who won the Nobel Peace Prize in 95, and there were 8 or 9 of us on the panel, including Cecil Powell, 200 00:20:15,840 --> 00:20:24,150 Otto Frisch, uh, George Rochester, and very well other who were the chemists who developed the emotions both at Kodak. 201 00:20:24,630 --> 00:20:32,310 And at Ilford. And this, this panel basically worked with the chemists to to increase the sensitivity of the emotions. 202 00:20:32,490 --> 00:20:43,490 Um, and in a, in a very, in an important way. So, um, so even as a graduate student, uh, Perkins was involved in panels which involved, uh, 203 00:20:43,500 --> 00:20:48,690 at least two Nobel laureates, and George Rochester should have got the Nobel Prize, but never did. 204 00:20:49,440 --> 00:20:53,879 Uh, he discovered the V particles, which afterwards were strangeness. 205 00:20:53,880 --> 00:21:01,260 But no one at the time realised for many years what they were. Um, so here is, uh, Don finally getting into the mountains. 206 00:21:01,260 --> 00:21:06,839 I don't know why. Quite why it took him quite so long to get to the mountains. But anyway, eventually he got to the young from York. 207 00:21:06,840 --> 00:21:12,810 This is a photograph. Um, actually went to Don's photographs, uh, of the young Flower York Observatory. 208 00:21:14,130 --> 00:21:20,640 Um, and he had, uh, he was doing various, um, uh, jobs that the young probably also here he is with a colleague, 209 00:21:21,090 --> 00:21:23,940 uh, actually trying to see if you bury deep into the ice, 210 00:21:23,940 --> 00:21:31,290 if there's some, um, effect on the number of particles you see, uh, as a function of the depth, apparently, this experiment didn't really work. 211 00:21:31,920 --> 00:21:38,000 Um, uh, but anyway, when he was, uh, working on this experiment, he, he approached the caretaker of the, 212 00:21:38,010 --> 00:21:42,840 um, for our bloke who spent his entire life on that observatory and didn't see people very often, 213 00:21:43,470 --> 00:21:50,610 um, and asked him if he could use some of his led because he wanted to, to melt it down and shape it so he could use it as a, as a absorber. 214 00:21:51,300 --> 00:21:57,060 Uh, and this led had been carefully work by this guy, the, the, uh, caretaker into beautiful shapes. 215 00:21:57,810 --> 00:22:01,710 And apparently he went out and asked if he could melt down this lead. This guy went completely ballistic. 216 00:22:02,310 --> 00:22:09,360 Um, and this is this guy's dog. This is just one of the most bizarre pictures I've ever seen. 217 00:22:09,840 --> 00:22:17,909 Uh, this is talk about. This seems to be completely rare, but I don't know where this is about to to bite down, but he doesn't seem at all concerned. 218 00:22:17,910 --> 00:22:22,260 He's off watching it with some sort of extraordinary. 219 00:22:22,770 --> 00:22:25,980 Um. Uh, I don't know what the word is. Interest. 220 00:22:26,640 --> 00:22:30,120 Um, so he had quite a few adventures, uh, in the Alps. 221 00:22:30,210 --> 00:22:33,690 Um, I don't think his skiing was very good at that stage, but probably got better. 222 00:22:35,260 --> 00:22:41,320 Um, so eventually this, uh, uh, panel managed to improve the sensitivity of emotions. 223 00:22:41,830 --> 00:22:44,290 Uh, and once you saw electric sensitive emotions, 224 00:22:44,290 --> 00:22:48,880 the electrons are very much more difficult to see because they leave much less ionisation behind them. 225 00:22:49,330 --> 00:22:56,020 But once you had an electron sensitive, uh, emotion, then you could see this whole pion coming in and decaying into a muon, 226 00:22:56,020 --> 00:23:00,520 and then the muon eventually decaying into an electron. And then it was clear what was going on. 227 00:23:00,520 --> 00:23:06,970 And these are for, uh, commu decays, um, from the early part of the 1950s. 228 00:23:08,220 --> 00:23:15,510 So then things became much clearer. Um, but this was quite a few years after Don's pioneering, pioneering work. 229 00:23:16,230 --> 00:23:22,080 So Don um left Imperial and arrived in Bristol just too late to share in the pie on discovery. 230 00:23:22,680 --> 00:23:28,800 Um, but he arrived in, uh, 1849 with a scholarship from the exhibition of 1851. 231 00:23:29,280 --> 00:23:36,250 Um, uh, apparently, according to the history of Bristol Physics, he also possibly also had a Royal Society MacKinnon scholarship. 232 00:23:36,300 --> 00:23:45,510 I'm not sure whether that was a mistake in Bristol physics, but anyway, uh, it's possible he had two sources of of, um, uh, funding. 233 00:23:46,550 --> 00:23:54,110 Um, so a wealth of physics poured out from Bristol in the 1950s and on Peter Fowler and Don, uh, were at the centre of it. 234 00:23:54,140 --> 00:23:57,379 This is the Bristol group. Um, in 1950. 235 00:23:57,380 --> 00:24:00,290 It's unfortunate the photographs, uh, had a bit of damage. 236 00:24:00,770 --> 00:24:06,709 Down here is is Cecil Powell, but you can scarcely see him cos his face has been somewhat obliterated. 237 00:24:06,710 --> 00:24:12,650 But Don is very clear, uh, and stands out uh, very clearly, though this is about 1950. 238 00:24:13,770 --> 00:24:19,530 Um, Peter follow was Don's sort of, uh, collaborator for many years at Bristol. 239 00:24:19,750 --> 00:24:26,070 This is a younger Peter Fowler. Uh, in 1930, um, he was Lord Rutherford's grandson. 240 00:24:26,430 --> 00:24:29,820 Um, so that was Lord Rutherford. Uh, and there's Peter. 241 00:24:30,210 --> 00:24:33,330 Um, I knew Peter very well. He was a delightful man. 242 00:24:33,330 --> 00:24:41,400 Extremely, extremely bright. It was astonishing that two people as bright, uh, as Peter and Don were at the same place at the same time. 243 00:24:42,280 --> 00:24:46,100 Uh, so there they are together. This isn't Bristol. I'm not quite sure where it is. 244 00:24:46,110 --> 00:24:50,280 And not only do I know who the two people in the middle are, but this is Don, obviously. 245 00:24:50,520 --> 00:24:53,010 Uh, and this is Peter. Um. 246 00:24:53,040 --> 00:25:00,500 Uh, so, uh, another thing that they did together was they were the first people to propose the use of the use of pions in cancer therapy. 247 00:25:00,510 --> 00:25:06,600 That was a nature article that they published, uh, towards the end of Don's time, uh, in Bristol in 1961. 248 00:25:08,600 --> 00:25:15,470 Um, so, uh, a lot of the work that John did, uh, in Bristol was related to the, uh, decays of the charged kaon. 249 00:25:15,950 --> 00:25:26,180 Um, the strangeness particles were first seen, as I mentioned, by Rochester and Butler in, in, uh, uh, um, uh, in 1947. 250 00:25:26,810 --> 00:25:31,310 Um, and these decays were particularly rich and confusing, and it took many years to unravel them. 251 00:25:31,310 --> 00:25:34,280 And Don and Peter played, uh, important roles in that. 252 00:25:34,310 --> 00:25:41,990 One of the, uh, things that they were doing was to, uh, in addition to exposures on mountains where the cosmic ray flux, 253 00:25:41,990 --> 00:25:47,750 of course, is higher, they also went even higher by using hydrogen filled balloons. 254 00:25:47,810 --> 00:25:50,959 Um, I'm not sure if this is Don. It looks like it might be. 255 00:25:50,960 --> 00:25:53,480 Don't remember. He had a sort of dirty old difficult like. 256 00:25:53,480 --> 00:26:00,139 But, um, and it's just of typical Don posture, so it could well be Don looking at this balloon going up. 257 00:26:00,140 --> 00:26:04,370 And of course, it was not, uh, it was not entirely hazard free, this balloon stuff. 258 00:26:04,430 --> 00:26:11,300 Uh, so here's a picture, um, of the aftermath of one balloon that, uh, exploded. 259 00:26:11,600 --> 00:26:17,030 Um, and those of you who who know will know that this is John Mosey. 260 00:26:17,750 --> 00:26:22,990 Uh, and this is Owen Locke. Um, who spent many, many years at, uh, at CERN. 261 00:26:23,000 --> 00:26:26,130 I don't remember who these two are. One is a guy called Davis. 262 00:26:26,150 --> 00:26:30,650 I don't know which one. Anyway, you can't tell. It's, like, completely burnt. 263 00:26:30,860 --> 00:26:35,420 Um, so it was dangerous, but, uh, they managed to do lots of very good work. 264 00:26:36,080 --> 00:26:41,900 Uh, one of the things Don's first book was, uh, the Bible of, um, emotions. 265 00:26:42,380 --> 00:26:49,790 Powell. Uh, what? Father and Perkins here is the first, uh, um, first edition, published in 1959. 266 00:26:50,630 --> 00:26:55,900 Um, and, uh, uh, they also went on to do many more things. 267 00:26:55,910 --> 00:26:58,560 This is a Don's, uh, list of publications. 268 00:26:58,880 --> 00:27:09,060 I would like to draw your attention to here is, uh, one which, um, is, uh, related to the King Perkins Tudor coffee effect. 269 00:27:09,110 --> 00:27:12,799 I didn't know that. Don't have that effect. But he does. 270 00:27:12,800 --> 00:27:18,620 The King Perkins critical effect. Uh, it's normally called the critical effect, but less of a mouthful. 271 00:27:19,100 --> 00:27:24,319 Uh, constitutive. Goff is the theorist who post-hoc, uh, decided what it was about. 272 00:27:24,320 --> 00:27:27,139 It's essentially, uh, quantum electrodynamics, uh, 273 00:27:27,140 --> 00:27:33,410 and relates to the screening of the other charge when you just produce an the C minus pair from a photon. 274 00:27:34,340 --> 00:27:41,780 Um, anyway, Don was the first person with this guy King to observe this, and he had a theoretical explanation, which was pretty good. 275 00:27:42,320 --> 00:27:46,760 Uh, but he took off, managed to steal the thunder. These theoreticians, they almost deal with them. 276 00:27:47,810 --> 00:27:53,420 Um, so that's the Perkins effect. And, uh, I didn't know about it, uh, until the research I did for this. 277 00:27:53,430 --> 00:27:57,589 This is some of his later publications, and you'll see that most of them, um, 278 00:27:57,590 --> 00:28:01,819 uh, are about, uh, essentially looking at nuclear physics type effects, uh, 279 00:28:01,820 --> 00:28:07,250 with emotions through cosmic rays, uh, flux of gamma rays at high altitude, 280 00:28:07,790 --> 00:28:11,540 production of pions and high prions and nuclear interactions at very high energy. 281 00:28:12,140 --> 00:28:16,010 Uh, and you start to see, um, some things which are to do with beams. 282 00:28:16,250 --> 00:28:21,140 There's the, the paper with Peter about applications for, uh, cancer therapy. 283 00:28:21,800 --> 00:28:25,130 Um, and down here, he spent some time at, uh, in Berkeley. 284 00:28:25,580 --> 00:28:32,540 Uh, where the first, uh, really, uh, accessible pion production machines were being run. 285 00:28:32,540 --> 00:28:37,220 Accelerators. Uh, he did quite a lot of work. And looking at, uh, kaon decays. 286 00:28:37,250 --> 00:28:45,590 Um, at that point there. But he already realised that, um, uh, basically emotions were running out of steam. 287 00:28:46,190 --> 00:28:53,720 Um, so by that 1950s, he was beginning to change his field and, uh, turning increasingly to the use of accelerators rather than cosmic rays. 288 00:28:54,140 --> 00:28:57,770 Uh, and he had the opportunity to come to Oxford in 1965. 289 00:28:57,770 --> 00:29:04,520 He was recruited by Dennis Wilkinson and he workers Ken on the other strategy professor uh, at the time. 290 00:29:04,520 --> 00:29:10,280 But it was his Imperial and Bristol work which was the basis for his election to the Royal Society. 291 00:29:10,430 --> 00:29:18,650 Uh, in 1966. Um, so just to finish, let me show you a couple of, uh, photographs. 292 00:29:18,660 --> 00:29:23,130 It's always fun to look at these photographs. You can spot, uh, all of your friends. 293 00:29:23,790 --> 00:29:27,150 Uh, this is the 40th anniversary of the Python conference. 294 00:29:29,640 --> 00:29:33,190 Uh, this was nominally chaired by Peter, and I was the secretary. 295 00:29:33,640 --> 00:29:38,410 So what that meant was that Peter would send me some jokes every now and again, and I would do all the work. 296 00:29:39,770 --> 00:29:47,530 Um, and we used to have, uh, committee meetings when Peter and Don were, while Peter was nominally chairing the committee, and Don was a member. 297 00:29:47,530 --> 00:29:52,240 So I don't remember us ever doing any work. But there were an enormous number of jokes were told at the time. 298 00:29:52,720 --> 00:29:58,390 Uh, no one will remember those committee meetings, which were by far the best committee meeting I've ever been involved with. 299 00:29:59,200 --> 00:30:04,860 Uh, there are lots of other people who have good old piles, uh, men on who was a great, uh, cosmic ray person. 300 00:30:04,870 --> 00:30:11,350 Uh, the Crespi from Poland. Uh, Don Davies from UCL as Peter Fowler. 301 00:30:11,410 --> 00:30:13,840 Um, this is Rosemary Fowler. 302 00:30:13,840 --> 00:30:24,370 His wife, Rosemary, um, was a, uh, actually was the first author on a lot of the early discoveries, um, related to kaon, uh, physics. 303 00:30:24,550 --> 00:30:28,290 Um, so she was a graduate student in her own right. Very unusual in those days. 304 00:30:28,310 --> 00:30:36,100 And there was a very interesting article, uh, in nature in January, uh, published by Susie, she which went into Rosemary's career. 305 00:30:36,160 --> 00:30:43,420 Um, as a physicist. Um, another example of women's contributions to physics, which have somehow, uh, been overlooked. 306 00:30:44,410 --> 00:30:49,780 Who else is that? This guy here is Wally. He was the wizard who produced all of these emotions. 307 00:30:50,140 --> 00:30:55,420 Uh, at the time, a remarkable guy. He was a chemist. But he came along to this physics conference and gave a remarkable lecture 308 00:30:56,110 --> 00:31:00,670 about how they managed to increase the density of silver inside the emotion, 309 00:31:01,030 --> 00:31:04,690 to therefore eventually be able to see, uh, electrons. 310 00:31:04,780 --> 00:31:10,060 Um, David. Vinnie. John. Mello's. Um, well, you can spot where that's done. 311 00:31:10,320 --> 00:31:15,490 I was for a moment, I couldn't see him. Paul Murphy, uh, a lot of good friends. 312 00:31:15,490 --> 00:31:19,450 David Saxon. Um, George, you must be there somewhere. 313 00:31:19,450 --> 00:31:24,069 I can't see anything. Oh, that's John movie. Uh, anyway, enough of this, uh, spotting. 314 00:31:24,070 --> 00:31:28,900 But here's some all this is, uh, slightly later, and I'll show this just because it's indicative, 315 00:31:29,290 --> 00:31:33,450 um, all of the leaders of particle physics at this time in the early 1990s. 316 00:31:33,460 --> 00:31:37,690 This is John May, lost his retirement as Don and as Peter. 317 00:31:37,690 --> 00:31:41,169 So this is one of the last photographs I have. Uh, of them two together. 318 00:31:41,170 --> 00:31:45,820 Peter died very, very early. Um, I don't remember precisely one, 2 or 3 years later. 319 00:31:46,480 --> 00:31:51,010 Um, uh, he was, uh, a great man. And Don and he were great friends. 320 00:31:51,700 --> 00:31:56,109 Uh, lots of other people who you'll recognise on here. Some of us are here today. 321 00:31:56,110 --> 00:32:03,219 George. Uh, and John, that's Robin Marshall. This was right end was the right place to sit because most of the rest are now dead. 322 00:32:03,220 --> 00:32:08,200 Except for Peter, who was still alive and kicking. Um, and there's me. 323 00:32:08,200 --> 00:32:12,070 I've got to the right end of the, uh, of this on the screen as Roger. 324 00:32:12,880 --> 00:32:16,960 Uh, who else? Who else can we spot? Greg Heath and Helen Heath. 325 00:32:17,230 --> 00:32:23,230 Um, nominal. See, that's some. I don't see you immediately, Norman. Uh, anyway, enough, uh, spotting. 326 00:32:23,230 --> 00:32:28,540 It's always great fun. Um, and many great friends, uh, particularly great friends of Don's. 327 00:32:29,350 --> 00:32:34,060 Uh, he and John May. Those were great friends. Uh, they shoot each other greatly. 328 00:32:35,200 --> 00:32:39,060 So let me just conclude with, uh, Don having the final word yet again. 329 00:32:39,070 --> 00:32:44,400 This is from another of his papers, but some things have not changed at all. 330 00:32:44,410 --> 00:32:50,790 50 years ago, Cecil Powell described his feelings on finding all those wonderful new processes, the nuclear emotions. 331 00:32:50,830 --> 00:32:55,420 He said it was as if suddenly we had broken into a walled orchard where protected 332 00:32:55,420 --> 00:33:00,100 trees flourished and all kinds of exotic fruits had ripened in great profusion. 333 00:33:00,640 --> 00:33:06,320 Well, the walled orchard still exists today. Perhaps they are not so easy to find, but they are there. 334 00:33:06,770 --> 00:33:10,810 I just for the new generation of physicists to find them, as I'm sure they will. 335 00:33:11,650 --> 00:33:11,950 Okay.