Number 128, May 11, 1993 by Phillip F. Schewe and Ben Stein
A RECORD HIGH SUPERCONDUCTING TRANSITION TEMPERATURE of 133 K has been
observed for a mercury-barium-calcium-copper oxide material developed by
scientists at the ETH lab in Zurich, Switzerland. The highest previous
transition temperature, 127 K for a thallium compound, was established
in 1988. (A. Schilling et al., Nature, 6 May 1993.)
VERY LOOSELY BOUND NEGATIVE IONS of atoms such as He, Ne, and Ca, created
by adding an extra electron to a neutral atom, do not hold onto their excess
charge for as long as predicted, forcing a revision in the theory. New
experiments at the ASTRID storage ring in Denmark have provided the first
measurements of the ions' lifetimes, which range from 10 microseconds to
100 milliseconds. These experiments are an example of the growing importance
of storage rings, long used in particle and nuclear physics, to the study
of atoms and molecules. According to Torkild Andersen of Aarhus University
in Denmark, who announced the ion lifetimes at the April APS meeting, some
ions are so fragile that they can be broken up by the infrared heat radiated
by the storage ring itself at room temperature. In some cases, this room-temperature
blackbody radiation is the determining factor in the ions' lifetimes. (Science
News, 1 May 1993.)
SEARCHES FOR NONZERO ELECTRIC DIPOLE MOMENTS in atoms and molecules
have the potential to test supersymmetry, a theory that emphasizes a hypothetical
symmetry between fermions and bosons in an effort to unify the electroweak
and strong forces into a single framework. This model predicts the existence
of a nonzero electric dipole moment at the level of 10**-27 cm (times the
charge of the electron) or, equivalently, that in some atoms the centers
of negative charge and positive charge should be offset by a very tiny
amount, less than 10**-27 cm (per unit charge). When the tabletop dipole
experiments at places like Amherst, Washington (Seattle), Berkeley, and
Yale reach the levels of precision needed for making this sort of measurement---they
are currently a factor of 10 away in precision---they will complement accelerator
experiments seeking to study supersymmetry. (Science, 30 April 1993.)
PREDICTIONS OF RATIOS OF CERTAIN HADRON MASSES based on lattice gauge
theory and more than a year's worth of supercomputer time have come within
6% of the observed values (F. Butler et al., 10 May Physical Review Letters).
Donald Weingarten and his colleagues at the IBM Watson Research Center
used a computer configuration that employed from 384 to 480 parallel processors
with speeds of 5 to 7 Gflops (billion operations per second). In lattice
theory simulations, the interactions among quarks inside hadrons (particles
that are made of quarks) are depicted as taking place in a jungle-gym-like
space-time world where quarks sit at fixed nodes. Weingarten believes that
numerically-derived results like his will constitute a legitimate adjunct
to rigorous theoretical calculations and experimental evidence. (The New
York Times, 11 May 1993.)
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