Number 29, April 11, 1991 by Phillip F. Schewe and Ben Stein
GRAND UNIFIED THEORIES of particle physics predict that at very high energies (1015 GeV), or equivalently at very early times after the Big Bang, the electromagnetic, weak, and strong forces should be comparable in strength. At the lower energies available at particle accelerators, the relative strengths of the forces are expressed as three "coupling constants." Using data at the LEP electron-positron collider at CERN, scientists have extrapolated the value of the coupling constants up into the energy range at which unification would take place. The failure of the three curves to intersect in a single point has been interpreted by some as evidence that new physical effects, not accounted for by the so-called Standard Model, may be at work. (CERN Courier, March 1991.)
DO NUCLEAR MOLECULES EXIST? Experiments at the Nuclear Structure Facility at Daresbury, England (a lab which may be closed because of budget cuts) indicate that during collisions nuclei sometimes behave as if they were "molecules" made up of discrete groups of nucleons rather than the more traditional "shells." For example, 24Mg nuclei can behave during collisions like a combination of two 12C nuclei; an 16O nucleus at times looks like an alpha particle (itself a nuclear fragment consisting of two neutrons and two protons) and a 12C nucleus in orbit around each other. At Daresbury, researchers are searching for a hyperdeformed version of 24Mg consisting of six alpha particles lined up in a row. (New Scientist, 6 April 1991.)
OZONE DEPLETION IS OCCURRING TWICE AS FAST as previously thought at the latitudes of the U.S., according to the EPA. The new EPA report disclosed that ozone losses during the 1980's was nearly 5%, a development which EPA head William Reilly called "disturbing." (Time Magazine, 15 April 1991.)
THE GAMMA-RAY OBSERVATORY has been deployed from the Space Shuttle Atlantis, notwithstanding a temporarily jammed antenna boom. The 17-ton, $600-million satellite is the second of NASA's four orbiting Great Observatories. The first was the Hubble Space Telescope; the other two, not to be launched until later in the decade, are the Advanced X-Ray Astrophysics Facility and the Space Infrared Telescope Facility. (The New York Times, April 8, 1991.)
SYNCHROTRON LIGHT SOURCES now under construction will greatly expand research performed with x-ray photons. Using wigglers or undulators, these new facilities maximize the synchrotron radiation shed by accelerated electrons or positrons. The European Synchrotron Radiation Facility (to be finished by 1994) in Grenoble, France, using 6-GeV electrons, will produce radiation that peaks at a wavelength of 0.86 angstroms. At the Advanced Photon Source at Argonne National Lab (scheduled for completion in 1995) positrons at an energy of 7 GeV will provide x rays in the energy range 4-40 keV. The price of the APS is $456 million, comparable to that of the ESRF. The third hard x-ray machine under construction is the Japanese SPring-8, which uses 8-GeV electrons; it will be completed in 1998. (Physics Today, April 1991.)
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