Work on Detection Device to Begin : UCSD Scientists to Go on Hunt for Monopole
This week, UC San Diego physicists plan to start building a large device to detect hypothetical particles left over from the fiery birth of the universe.
If successful, the project could hasten physicists’ effort to find a theory unifying all physical forces, project leader George Masek said.
The goal of the $125,000 project, which is 90% funded by the National Science Foundation, is to detect a magnetic monopole--a particle that has only one pole, north or south.
The existence of magnetic monopoles is predicted by some versions of the Grand Unified Theory (GUT) popularized by the world’s top physicists in the 1970s.
In GUT’s best-known form, it would simplify into one theory the four known forces, which are gravity, electromagnetism, the so-called “strong” force that binds the atomic nucleus together and the “weak” force that is responsible for radioactive decay of atomic particles.
Physicists have long tried to develop a theory that would explain all these forces under one umbrella. When Albert Einstein died, he was trying to develop such a theory.
The theory would not have any immediate practical value, but physicists believe it is worth pursing in order to obtain a more complete picture of the way the universe works.
Masek, 58, acknowledged that monopoles could be “10 times more common than we estimate--or 10 times less. Or it could be that they’re not there at all.”
To try to resolve the issue, Masek is erecting a monopole detector in a storage building in a field across from Scripps Memorial Hospital. Upon completion, it will consist of 2,330 25-foot-long aluminum tubes stacked in a 6-foot-high, 25-foot-wide array covered with computer cables.
Countless types of subatomic particles are flying around us every moment, and the UCSD detector should be able to distinguish a magnetic monopole from the rest by its uniquely slow speed.
A monopole is expected to move relatively slowly--perhaps one one-thousandth the speed of light--because it is believed to be the heaviest of all subatomic particles.
“I think that if you polled 100 physicists dealing with elementary particles, the majority of them would say they don’t think we’ll see a monopole. This GUT theory is very new, very speculative,” Masek said.
And if he does detect one, then plenty of hefty textbooks sitting on library shelves might have to be rewritten, he said. “It would be one of the big discoveries of modern physics.
“But, I must emphasize, it’s a long shot.”
Masek said the new experiment (called Phase Two) will be the largest monopole-detecting device of its type in the world, and about 20 times bigger in volume than a prototype (called Phase One) in operation in the basement of Urey Hall at UCSD.
Phase One was built for $30,000--80% of which came from NSF--and consists of 225 aluminum tubes stacked in a six-layer array, three feet by 25 feet.
Phases One and Two work on the same principle:
The aluminum tubes are full of helium and methane gases. A monopole passing through the detector should ionize--that is, knock electrons off--atoms of gas inside the tubes. These “free electrons” should then be attracted to a thin, electrified wire that runs the length of each tube. The wire will transmit a signal from the electrons to instruments that measure both the time and intensity of the ionization.
Then the data are transmitted to a computer at Stanford University. The computer determines how fast the particle was traveling.
If it was traveling in a straight line (“they’re big massive things, they plow right through and nothing causes them to deviate”) and if it appears to be traveling at a slow enough speed, then it might well be a monopole, Masek said.
Staffers involved in the UCSD monopole project are Masek, UCSD physics professor Wayne Vernon, physics graduate student James White, post-doctoral researcher Ed Miller, and a number of technicians including Jim Stronski and Lee Knapp.
The project is the result of calculations by Norman Kroll, the head of the UCSD physics department, and his colleagues that proved the ionization technique could be used to detect monopoles.
The existence of magnetic monopoles was first suggested a half-century ago by the physicist Paul Dirac.
Five times, the UCSD prototype has detected curious objects that resembled monopoles. But further analysis indicated they undoubtedly were spurious phenomena caused by electrons that took a considerable amount of time to escape from the corners of the squarish tubes, Masek said. By moving slowly, the electrons simulated a slow-moving particle--i.e., a monopole--passing through the array of tubes.
To prevent more such illusions, the tubes in Phase Two will be round.
He plans to report the negative results of Phase One this summer at a scientific gathering in Italy.
In 1982, Stanford researcher Blas Cabrera thought he detected a monopole using a different type of apparatus. The observation has been questioned by skeptics, however.
Other monopole searches are under way at Stanford and in Minnesota, Chicago, the Soviet Union, Japan and India.
