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TRIUMF Researchers Solve Fusion Bottleneck

News Release | For Immediate Release | August 29, 2000

(Vancouver, BC) -- Researchers at TRIUMF, Canada's national laboratory for particle and nuclear physics on the campus of the University of British Columbia, have observed a dramatic enhancement in the formation of hydrogen isotope molecules when using a secondary particle called the muon as a go-between. The research, published in the prestigious journal Physics Review Letters (August 2000), attracted the attention of the American Physical Society's online magazine Physical Review Focus, which selects topics for their intrinsic interest to non-specialists.

In the tour de force experiment, a low velocity beam of muonic tritium atoms collided with a low temperature solid consisting of molecules made up of two atoms of deuterium. Normally the tritium atom, an isotope of hydrogen, is made of a triton, or a nucleus consisting of a proton and two neutrons, encircled by an electron. In muonic tritium, however, the electron is replaced by a heavier but short-lived particle called a muon, which can be made in great numbers at the TRIUMF facility. Deuterium is another isotope of hydrogen, with a nucleus consisting of a deuteron (one proton and one neutron) encircled by an electron.

The results of the collisions were exotic molecules in which the muon forced two nuclei, one deuteron and one triton, to be very close to each other, a condition which favors their nuclear fusion to produce a helium nucleus (two protons and two neutrons), a free neutron, plus energy; the muon also remains to catalyze subsequent fusions. The molecular formation rate was observed to be dramatically enhanced at specific energies of the muonic tritium beam by what is known as a resonant process, which was in fact fast enough that the muon could be recylced over and over again, potentially thousands of times, during its brief lifetime (only 2.2 millionths of a second). In this way, one of the bottlenecks in the efficient production of fusion using muons can be avoided.

There remains another bottleneck, however, to the production of more energy than what is needed to produce the muon in the TRIUMF accelerator complex in the first place. At least one in two hundred occurences of muon catalyzed fusion will result in the muon sticking to the helium nucleus, thereby interrupting the cycle and reducing the energy liberated per muon.

The experimental collaboration consisted of over twenty scientists and students from Canada, the United States, Europe and Korea. It was funded mainly by the Natural Sciences and Engineering Research Council of Canada (NSERC), with significant contributions from agencies in other countries. Two students received doctoral degress from the project, Dr. M.C. Fujiwara at the University of British Columbia and Dr. T.A. Porcelli at the University of Victoria.

TRIUMF is operated under a contribution from Canada's National Research Council (NRC) as a joint venture by the University of British Columbia, Simon Fraser University, the University of Victoria, the University of Albert and Carelton University.


TRIUMF is Canada's National Laboratory for Particle and Nuclear Physics. Located on the south campus of the University of British Columbia, TRIUMF is owned and operated as a joint venture by a consortium of the following Canadian universities, via a contribution through the National Research Council Canada: University of Alberta, University of British Columbia, University of Calgary, Carleton University, University of Guelph, University of Manitoba, McMaster University, Université de Montréal, Queen's University, University of Regina, Simon Fraser University, Saint Mary's University, University of Toronto, University of Victoria, York University.


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