Won the Nobel Prize in 1994 for designing the Triple-Axis Neutron Spectroscope and his use of it to investigate Condensed Matter
"Your mind is your most valuable survival organ. Learn to tune your mind like a radio, filtering out all the noise and other channels, focusing on one thing."
On an ordinary Wednesday morning in October 1994, Bert Brockhouse gets out of bed at his usual time, about 6:45 a.m. As he stretches a bit to loosen the overnight aches of his 76-year-old body, he sees the little red light blinking on the answering machine. “Who could have called in the middle of the night?” he wonders, as he presses the play button.
He listens to a voice announcing that the call is from Stockholm, Sweden: “B. N. Brockhouse and C. G. Shull have been selected as recipients of the 1994 Nobel Prize for physics.” Brockhouse is stunned. For a moment he thinks, “Oh, that’s interesting,” but then he realizes, “I am B. N. Brockhouse!”
He calls his wife Doris to listen to the tape with him. The rest of the day is filled with phone calls, telegrams and interviews for Brockhouse, who had been retired.
The next year is one of travel, awards, banquets and lectures. Brockhouse is simply beamed out of quiet retirement. In his annual Christmas letter to friends that year, after describing all the festivities in Stockholm, he writes, “If anyone cares, we got a new car in the summer, a Chrysler Neon.”
The origins of Brockhouse’s Nobel Prize lie back in 1951. Fresh out of the University of Toronto with a doctorate (PhD) in physics, he sat at his desk in a faded, blue-shingled wartime hut at Chalk River, home of the Atomic Energy Project funded by Canada’s National Research Council.
Brockhouse gazed out the window at the snow. It was winter, but he felt warm inside the hut. He just sat there, thinking, mulling things over in his mind. The other night he had been at the home of Donald Hurst, his boss and head of the neutron spectrometer section. They had been reading a 1944 paper about neutrons — subatomic particles with no electric charge that, together with protons, make up the nucleus of an atom.
The existence of neutrons had been verified only about 12 years before. Not much was known about them. Brockhouse didn’t quite understand the theories in the paper, but he felt it had a lot of interesting ideas. He was supposed to be working on something else, but he couldn’t stop thinking about the concepts in that paper and how he could do experiments at Chalk River to try out some of the new theories. He fiddled with some math on his notepad for a while and then went to the coffee room.
As he passed the lab that housed the radioactive nuclear pile, a controlled nuclear reaction that emitted one of the most powerful sources of neutrons in the world at the time, he wondered whether he could put it to use. In the coffee room he met Hurst. Brockhouse went up to the blackboard and said, “Don, there’s something I’d like to show you.” He sketched out some equations on the blackboard. The math described a device they could build that would use a neutron beam as a better type of spectrometer, a kind of flashlight that could probe the mysteries of crystal structures and other solids such as metals, minerals, gems and rocks.
In the 1920s, Bert Brockhouse’s family moved from Lethbridge, Alberta, to Vancouver, British Columbia. They operated a rooming house in the city’s West End and Bert had a paper route to help supplement the family income. He liked fishing and went with his buddies to catch shiners, cod and salmon off the pier at English Bay. He fooled around with radios a lot as a teenager, hanging out at radio repair shops and building homemade radios from designs in popular electronics magazines.
After high school, instead of going to university, he worked as a radio repairman. Then World War II came along and he used his radio skills as an electronics technician in the Canadian Naval Reserve. When the war ended, Brockhouse went to the University of British Columbia, majoring in math and physics. After marrying Doris, a film cutter at the National Film Board, he finished his doctorate and the newlyweds moved to Chalk River. Brockhouse spent his working life as a researcher at Chalk River perfecting neutron spectroscopes and their applications. He solved problems controlling the source of the neutron beam; limiting it to neutrons of only one energy; getting rid of background radiation from other experiments in the lab; and problems with the sensitivity of the detectors. The resulting triple-axis neutron spectrometer is now used worldwide to investigate crystal structures.
Brockhouse conducted experiments in the physics of solids such as metals and crystals. This kind of physics is called solid state physics. As his tool he used the neutron spectrometer that he developed at Chalk River, which allowed him to look right inside the crystalline structure of solids to find out how solid things like rocks and gems are held together. Imagine shining a beam of light on an object. Your concept of that object is based on the light reflected from it.
But at the atomic level, the wavelength of the light beam is “too big.” The wavelength (or the “size”) of the light from a flashlight is about 7,000 Angstroms (one Angstrom is roughly the width of a hydrogen atom, or 10-10 metre), while the wavelength of a neutron beam is only around one to four Angstroms. In other words, if you could use a beam of neutron “light” you could see details thousands of times finer than you can see with ordinary light. Incidentally, in the same way, the shorter wavelength of X-rays is what gives them the power to penetrate things and reveal inner details that you cannot see with regular light. According to Brockhouse, “the virtue of neutrons is you can say a great deal about a material by using a neutron beam.” You can work out the distance between atoms, the angle of bonds between atoms, the strength and energy of atomic bonds holding the atoms of a solid together, and much more. All these things are very handy and can be applied to working with metal, rocks, gems and other solid materials. But, fundamentally, Brockhouse was just trying to satisfy his natural human curiosity. He wanted to know what things are made of, what rocks look like inside.
1. The original triple axis spectrometer (1959). (Click image to enlarge.) A spectrometer is a device that measures the angle, wavelength and energy of light or other type of radiation, in this case neutron radiation. The panel of 52 rotary switches in the upper centre of the picture could be preset to go through an energy scan of up to 26 points. A feature of Brockhouse’s spectrometer was the way he could vary three angles: the direction of the neutron beam, the position of the specimen, and the angle of the detector. Add to this the ability to vary the energy of the incoming neutrons and the sensitivity of the detector and he had a Nobel Prize-winning creation. (Photo courtesy of AECL)
2. Monochromating Crystal. “Monochromating” literally means “making one colour.” A special crystal of aluminum was used to separate out neutrons of one particular energy or colour. Knowing the exact colour of the beam going in can tell you more about what is inside the material you are investigating. The beam was then aimed and collimated (straightened out by going through a series of slits) before being sent on to the target.
3. Specimen. The position of the target metal or crystal can be varied on two axes (twirled around sideways or vertically, for instance). The beam of neutrons bounces off the target in different directions that tell something about the atomic structure of the material if they can be detected.
4. Detector. The analyzing crystal, similar to the monochromating crystal, can be tuned to pass only neutrons of particular energies. These neutrons then pass through the analyzing crystal on to the detector, which counts them. By knowing the energy, quantity and angle of the neutrons that go into the specimen and then measuring the energy, quantity and angle of the neutrons that come out, physicists can calculate things about the internal structure of the specimen.
Like many retired physicists, Brockhouse liked to explore metaphysical ideas — concepts such as spirit, morality, ethics and beliefs. For the last two decades of his life he worked on what he called “The Grand Atlas,” a sort of rule book for nature incorporating theories both physical and metaphysical. Brockhouse was a religious man, and his belief in physics theory coexisted with his spiritual beliefs. “Science is an act of faith,” he said.
Without faith, how can understanding the existence of a neutron help with the larger moral issues in life?
Brockhouse’s example of a moral problem is “Kantian Doom” — the idea that we are doomed because even though we know that something is bad for us, we do it anyway because everyone else is doing it. Examples might be driving cars, using computers or watching television. Brockhouse believed such problems might require metaphysical solutions, not scientific ones.
Fritjof Capra, The Tao of Physics, fourth edition, Shambhala Books, 2000.
Brockhouse's autobiography on the Nobel website.
Neutron spectroscopy lab in Budapest, Hungary.
Brockhouse believed that the most important thing a person could learn and apply in one's career is discrimination, in the sense that one must learn to tune out the bad stuff and focus on the good, like a radio tunes into just one frequency.