PHYSICS NEWS UPDATE A digest of physics news items prepared by Phillip F. Schewe, AIP Publ

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PHYSICS NEWS UPDATE A digest of physics news items prepared by Phillip F. Schewe, AIP Public Information Number 151 November 15, 1993 JOHN PEOPLES WILL OVERSEE THE DISMEMBERMENT OF THE SSC while retaining his directorship at Fermilab. Peoples replaces Roy Schwitters, who resigned last week as head of the SSC. An estimated $1.5 billion in SSC shutdown money will go largely for severance to displaced SSC employees and for settling claims from SSC contractors. (The New York Times, 9 Nov. 1993.) DISPOSSESSED AMERICAN PARTICLE PHYSICISTS are looking around for alternative research venues. British science minister William Waldegrave has suggested informally that "CERN should immediately invite the US in as a member state." Other countries such as Italy and France are not keen on this idea, not wanting the US (or Japan) to gain an undue influence over what until now has been a European venture. Stanford scientist Sidney Drell favors the creation of a whole new, truly worldwide, Center for International Nuclear Research (CIRN). Short term plans must also be pursued. Tom Kirk, who left Fermilab for the SSC, says that some of the scientists who worked with him on the Solenoidal Detector Collaboration (SDC) at SSC may be able to apply the fruits of their efforts (knowledge if not hardware) in some way to the development of detectors at the proposed Large Hadron Collider at CERN. (Physics World, Nov. 1993.) A SELF-FOCUSING LASER has been developed at AT&T Bell Labs. The layered semiconductor device is patterned on top with a set of micron-sized concentric grooves, which constitute a sort of Fresnel lens. Infrared laser light, emitted from this top face, is focused to an 8-micron spot size. Daryoosh Vakhshoori of Bell Labs believes this "zone laser" will promote a better coupling of laser light into external optical fibers. (Science News, 6 Nov. 1993.) SOLAR RADIATION VARIES only a few tenths of a percent at visible wavelengths over the sun's activity cycle, but varies by as much as a factor of 10 at extreme-ultraviolet and x-ray wavelengths. Solar UV radiation has an important role in Earth's atmospheric chemistry, particularly in the formation of stratospheric ozone. UV rays help to make ozone (from atmospheric oxygen) in the first place; then the ozone protects living organisms from harmful effects of the UV. The sun's UV flux, monitored by the Upper Atmospheric Research Satellite (UARS), is declining now as the sun passes into the less-active part of its 11-year cycle. By studying the solar UV spectrum over short and long periods of time, UARS hopes to provide information that can lead to a differentiation between natural and anthropogenic sources of ozone variability. (Physics World, Oct. 1993.) MOLECULAR DYNAMICS (MD) SIMULATIONS have gotten faster. These computer studies track the behavior of a hypothetical ensemble of particles subject to a specific law of motion incorporating the complex interactions among neighboring particles. As part of a study of supersonic projectiles, scientists at Los Alamos have simulated the 3-dimensional movement of 180 million particles, with 4 updated configurations per microsecond. Less than a year ago, the largest comparable MD simulation tracked 17 million particles. The Los Alamos computer system had a sustained speed of 50 Gigaflops. (Physics World, Oct. 1993.)

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