Nobel Prize Winning Work on Neutrons
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The Empire Club of Canada Addresses (Toronto, Canada), 19 Jan 1995, p. 501-510
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Brockhouse, Dr. Bertram, Speaker
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Some personal reminiscences. Neutron physics. The study of the neutron itself as an object. The use of the neutron. Neutron spectroscopy. A brief history of the modern era of neutron scattering. What neutrons do. How neutron spectroscopy works. Confidence as one of the chief products of experimentation. Scientific results as by-products of endeavours which have other objects in view.
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19 Jan 1995
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English
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Full Text
Dr. Bertram Brockhouse, Professor Emeritus, McMaster University
NOBEL PRIZE WINNING WORK ON NEUTRONS
Chairman: John A. Campion
President, The Empire Club of Canada

Head Table Guests

Jan Dymond, Vice-President, ZED Communications and a Director, The Empire Club of Canada; Shannon McLaren, grade 13 student, Lawrence Park Collegiate Institute; The Rev. Edward Jackman, Historian, Archdiocese of Toronto; Doris Brockhouse; Barry Nichol, Chair, Board of Governors, McMaster University; Dr. Geraldine Kenney-Wallace, President and Vice-Chancellor, McMaster University; Julie Hannaford, Partner, Borden & Elliot and 2nd Vice-President, The Empire Club of Canada; Hamish Simpson, Headmaster, Upper Canada College Preparatory School; James Taylor, Chancellor, McMaster University; and Dr. Terry Rummery, President, Atomic Energy of Canada Ltd.

Introduction by John Campion

Einstein's Eclipse

The modern world began on May 29, 1919, when photographs of a solar eclipse, taken on the Island of Principe off West Africa and off Sobral in Brazil, confirmed the truth of a new theory of the universe. For half a century, Newtonian cosmology, based upon the straight line, Euclidean geometry and Galileo's notion of absolute time, was in need of serious modification.

In 1905, Albert Einstein, then a 26-year-old working in a Swiss patent office in Bern, had published a paper: "On the Electrodynamics of Moving Bodies," which became known as the special theory of relativity. The originality of his thinking and the elegance of his lines of argument aroused world-wide interest. In 1907, Einstein published a demonstration that all mass has energy encapsulated in the equation E=MC2. This was seen as the starting point for the race for atomic weapons and their peaceful application to the production of nuclear energy and nuclear medicine.

Einstein developed his general theory of relativity by 1915. His paper was smuggled out of Germany through The Netherlands and delivered to Professor Eddington at Cambridge at the height of World War I. Einstein had said that his theory had to be proved by three tests. The first, being the most important of these tests, involved photographing a solar eclipse to determine that a ray of light was bent by 1.745 seconds of arc as it grazed the sun.

Eddington led the expedition to West Africa, waited anxiously through a thunderstorm while the time for a total eclipse arrived and was able to take his photographs in May of 1919, which, after they were reviewed, confirmed that Einstein was right. No exercise in scientific verification has ever attracted so many world headlines.

Dr. Bertram Brockhouse was nine months old in May of 1919. He is the inheritor of the Einstein studies and theories. He has gone on to assume a Laureate position in the world of science. He is Canada's Nobel Prize Laureate for 1994.

The Nobel Prize was itself born in equivocation. It celebrates those who have made valuable contributions to the good of humanity in the fields of physics, chemistry, physiology or medicine, literature, economics and peace. The equivocation is that it was financed from profits made from the manufacture of, among other chemical products such as artificial rubber, leather, silk and precious stone, chemical explosives which were invented and manufactured by Alfred Nobel, a Swedish chemist and industrialist. These chemical explosives became dynamite, used for peace and war.

The Nobel Prize shares this equivocation with nuclear physics. Nuclear theory in physics represents a God-like power. We celebrate that power, but we as humans must revere and respect its awesome force.

It is to this area that Dr. Bertram Neville Brockhouse has applied his scientific life's work. He graduated with a Doctorate in Science from the University of Toronto in 1950. He was a lecturer at that university for one year before he joined the Department of Physics at Atomic Energy of Canada Limited in Chalk River, Ontario, where he remained for 12 years. In 1962, he joined the Department of Physics at McMaster University and became its Chairman in 1967. He is now a Professor Emeritus at McMaster University in Hamilton.

He has an extraordinary list of honours, ranging from 1962 to 1984. These include scientific as well as general public awards. He is a member of the Order of Canada and has an Honorary Doctorate of Science from the University of Waterloo and McMaster University.

Dr. Brockhouse was awarded a Nobel Prize in 1994 for the invention of the triple-axis neutron spectrometer which created a new field and made possible, for the first time, accurate and detailed information concerning the nature of condensed matter. His work has illumined the work of a host of other experimental and theoretical physicists in the field of solid state physics. It is with special pleasure that I ask you to rise, honour and welcome Dr. Brockhouse.

Bertram Brockhouse

Thank you very much. I will apologise at once for the voice that will squeak at you from time to time because I have a bit of asthma. I am especially glad to be a guest of this famous Club, which I rather think I've known all my life. I've known about it at a great distance, because I grew up in Vancouver.

I grew up in a world where we were moderately proud to be subjects of the Queen and the Empress, or (in those days) the King. We were proud, moderately, of the British Empire and of what it did in the world. I still think this is probably the case.

Now I am not going to read a speech; in fact I don't have a written speech fully prepared. But formerly you were not supposed to read speeches. If you were in some august assembly, such as a parliament, to read the speech was a little bit out of the way of how things were done. You were supposed to speak plainly, person to person. Now I am going to use the view graph as my guide to what I should be telling you.

The Nobel Prize award was, to me, totally unexpected. In your 76th year, you don't exactly expect such a thing to come about. On October 12 at 6:45 a.m., the life of my wife also showed a great change. Now, as the Chairman noted, Nobel prizes are awarded by the King of Sweden for physics, chemistry, literature, medicine and physiology. Also other prizes in honour of Alfred Nobel, facilities and money are contributed from other sources. The Peace Prize is awarded in Oslo by the King of Norway.

Now there is a lesson in Scandinavia for Canada in 1994 and 1995. In 1905, Norway, which had been part of a united kingdom with Sweden for something like 100 years, separated peacefully from Sweden. It was brought about by the rapid changes in the politics with which countries of that era were governed. The King was of great power at the beginning of the nineteenth century. Gradually, power shifted from the king and his aids to a parliament and its operators. So the stress that this change put on the united country of Sweden and Norway resulted in their separation in 1905. The Peace Prize was thenceforth awarded at the hands of the King of Norway.

Now before going on to other topics, I am going to show you a picture that was taken at Uppsala University. I think the Rector of Uppsala University and some of the Nobel laureates are shown--one of the two medical doctors who received the prizes for medicine and physiology, the person who shared the prize in physics with me and the person from California and Hungary who was awarded the prize in chemistry. These two gentlemen are two of the three awardees of the economics prize which was awarded for work in the theory of gains. The Theory of Gains in Economic Behaviour is a very famous book of 50 years or so ago, and their work followed it.

Now I won't say too much about my own subject here, because I think it is not that appropriate for the audience as I envisage it, but I will say a little. The Neutron and its Application. That is the title of a book, published in 1982, celebrating the fiftieth anniversary of the discovery of the neutron. The uses mentioned are military, medical and energy supply. There are also a lot of scientific uses, which are not as well known, perhaps, and bear just a little discussion.

The neutron is a nuclear particle. The theory is that it shares its place with the proton inside the nucleus of any atom. So it is naturally of interest as a projectile.

But that doesn't concern me here. What I am concerned with are what has come to be called neutron physics. One aspect is, trivially, the study of the neutron itself as an object. This little tiny thing has, as we think of it, a diameter of 10-15 of a metre. This little tiny object, according to quantum mechanics and according to all the work by which the neutron has been investigated, is simultaneously a particle and a wave. And this, of course, probably indicates that it is neither a particle nor a wave. That is how we see it with our three-dimensional minds and three-dimensional world in which we believe we live.

Beyond that there is the use of the neutron, or beams of neutrons, as a probe to investigate matter in its various forms. I'm specifically concerned with neutron spectroscopy, which enquires what happens to neutron velocity and energy when they are scattered. From this you get some idea of what is going on within the particular specimen which is being studied.

This is a second book called Fifty Years of Neutrons Scattering.

It is strange that I should've been picked out of retirement for this remarkable honour. Well, it gives one great pause. Quite incredible. If one were to believe in such things as fairies and fairy-land, then one might have some theory about it.

Now what happened was that long after the early fifties, up to '57 or '58, when the NRU reactor at Chalk River was commissioned, we started into the modern era of neutron scattering. Many papers were published each year. I had a book published in 1974.

I now have to decide what I'm going to talk about in the remaining few minutes. I don't know how much you are interested in hearing what neutrons do, but this is the kind of apparatus that would be used. This is a picture of the NRX reactor, the one that I used in about 1950. It was a large heavy apparatus, in order to shield against emissions of neutrons and gamma rays and so on.

And this is a picture of the apparatus that was mentioned by the President in his introduction, the constant-Q apparatus. This would be from 1958--one of the first, I think, uses of the computer in controlling pieces of equipment. The computer at that time of course was a vacuum tube apparatus with, by your current standards, ridiculously small capabilities. It emitted enormous amounts of heat and filled a large room. But it would provide numbers, which could then be set on a large bank of switches, to control the operation of the reactor, and of the spectrometer, in using the beam of neutrons which came from behind the shielding. It was used in studying various crystals and so on. Although it had ridiculously small capabilities compared with the computer that probably sits on many of your desks, it was nevertheless enormously capable compared with sitting at a desk oneself with a hand calculator and putting out reams of numbers in some complicated calculation.

Now at this point, we'll just see for a moment what can be done from spectroscopy. We are limited to observing things that go on in this three-dimensional world. The three-dimensional world, which is three-dimensional probably because our minds construct it that way, creates great difficulty in getting directly at the terms of the theories, particularly those in physics. And in the physics of solids there are similar terms. There is the velocity of high-frequency sound, an analogy to the velocity of light. There is a velocity for propagation of what we could term sound if it were low frequency, but frequencies of 100,000,000 times or so the frequencies of ordinary sound are propagating through the crystals, according to the theory. They propagate through other solids as well, but they are more difficult to get at. Just as we have protons and neutrons, we have things that have been named phonons and magnons and rotons. These are quasi particles which exist only in a particular universe of discourse, which is that specimen material. The specimen material may be aluminum, copper, sodium chloride or whatever, up to all the manifold chemical combinations that one can generate of the atomic elements.

So neutron spectroscopy enables one to get at these things directly and "see" (metaphorically of course) protons, neutrons, nuclei and atoms. We can get the forces between atoms, to an extent. We get a handle on what the actual forces are between the sodium and the chlorine, and the sodium and the sodium, and so on, in a crystal of common salt.

We have several other things. Of interest are correlation functions--a kind of moving picture of what the atoms are doing made by a sufficiently large set of measurements on the figure specimen. Thousands of scientists around the world use the technique in studying all sorts of things now, including bilateral objects and certain technological objects from an applied point of view.

I would conclude by saying a word about this Grand Atlas. This enormous scientific catalogue of scientific results can be conceived as analogous to ordinary geography. You have geography, geology, and the recipes of physics and chemistry. From these experiments you get a metaphorical geography, just as morals. People have thought of moral geography in history. The Grand Atlas is the analogue of an ordinary atlas, but of an enormous scope.

One of the chief results of experiments such as those which my colleagues and myself have done over the years and which are now conducted by a large number of people is confidence. Because you're getting at the very roots, the guts of the theories that you used in conceptualising and talking. We talk about atoms, don't we? We talk about the electrons, the holes and the electrons in semi-conductors, and all these things. If you have experimental methods, you get at the very things themselves and do not have to rely on enormous calculations from a theoretical base for whatever you observe in real life or in the laboratory. So it's this confidence which is one of the chief products.

The other product, of course, is the language itself. You produce the language with which the inventor or the lay people apply science in any way. You produce the language which they use in conceptualising what they are doing, and what they are trying to do. Now I haven't got time to develop this notion (which is one of my interests), hut one last point is that very often, there is the possibility of scientific results as by-products of endeavours which have other objects in view. Actually, for many of the people in this field that I have been talking about, the results were a by-product. NRX and NRU were not built to do this work. NRX and NRU were built, I take it, to develop the techniques and the apparatus for getting nuclear electrical power. There are reactors in the world dedicated to my objects of research. But I won't go into that.

I think I have said what I had to say. I have had to cut a bit, as you observed. Thank you.

The appreciation of the meeting was expressed by Julie Hannaford, Partner, Borden & Elliot and 2nd Vice-President, The Empire Club of Canada.

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Nobel Prize Winning Work on Neutrons


Some personal reminiscences. Neutron physics. The study of the neutron itself as an object. The use of the neutron. Neutron spectroscopy. A brief history of the modern era of neutron scattering. What neutrons do. How neutron spectroscopy works. Confidence as one of the chief products of experimentation. Scientific results as by-products of endeavours which have other objects in view.