Looking for the W

Abstract

The world's most powerful particle accelerator, the 76-billion-electron-volt synchrotron now beginning experimentation at Serpukhov in Russia, is expected to look for many things never before seen in the world of particle physics. One of them may be the long sought, intermediate vector boson. We are trying hard to persuade them to set up to look for it, says Prof. R. E. Marshak of the University of Rochester, who has spent many years studying the kinds of interactions in which the boson ought to play a role. He explains that Serpukhov is the only accelerator in the world that can put enough energy into a particle collision so that there is a hope of creating it. Intermediate vector boson is more a classification than a name. Intermediate stands for its function as the carrier of a force-in particle physics it has proven profitable to regard a force between two particles as if it were embodied and carried by a third and intermediate particle. Vector is the name of the mathematical entity that is used in describing the particle's activities. Boson means that such particles would obey statistical behavior laws derived by S. N. Bose and Albert Einstein. For short, this postulated particle is usually designated W, in recognition of its hypothetical function as carrier of the weak subatomic forces. The weak force is one of the large puzzles in particle physics; the way it fits into the rest of the universe is far from clear. It looked superfluiotus when it was discovereed, and no one is yet sure what function it serves. When physicists started to investigate atomic nuclei, they were already familiar with two general classes of forces, gravitational and electromagnetic. It soon became clear that the force that held nuclei together represented a third class. It was much stronger than the other two, it took no notice of electric charges and its range, unlike the infinite range of the macroscopic forces, was confined to a space about the size of the largest nucleus. But there was one nuclear phenomenon that this strong force did not explain-beta decay. In certain radioactive nuclei a neutron will spontaneously turn into a proton, emitting by the way an electron-a beta particle-and an antineutrino. This also happens to free neutrons. The force involved in beta decay, thouLgh also of short range, was much weaker than the strong force and even than the electromagnetic. And it was far slower than the strong force: The life-