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

PHYSICS NEWS UPDATE
A digest of physics news items prepared by Phillip F. Schewe, AIP
Public Information
Number 166  February 25, 1994

METASTABLE ANTIPROTONIC HELIUM ATOMS are made by
shooting beams of antiprotons into liquid helium.  Experiments at the
KEK lab in Japan in 1991 showed that the annihilation of some
antiprotons was greatly delayed (from an expected lifetime of
picoseconds to an observed interval as long as microseconds),
suggesting the creation of a metastable state.  The same scientists, in
collaboration with physicists from Germany and Hungary, have now
performed the first laser spectroscopy studies of these exotic atoms.
They conclude that the longevity of the antiprotons in helium results
from the formation of a neutral atom consisting of an antiproton and
a helium ion.  The researchers deduce that the observed emissions at
a wavelength of 597 nm correspond to the transition from one high-
energy, high-orbital-momentum state (n=39, l=35) to another
(n=38, l=34).  (N. Morita et al., 21 Feb. 1994, Physical Review
Letters.)

ARE ELLIPTICAL GALAXIES BORN IN THE COLLISIONS OF
SPIRAL GALAXIES?  The main argument against this hypothesis is
the fact that globular clusters are more numerous in ellipticals than in
spirals.  One would have thought that some of the globulars would be
lost in the collision and that they would therefore be less prevalent in
ellipticals.  Recent Hubble Space Telescope pictures of colliding
spirals suggest, however, that new globular clusters may be formed
in the collision process, notwithstanding the tendency (at least in our
galaxy) for globular clusters to be extremely old structures.
According to M.G. Edmunds of the University of Wales, the
demonstration that new globular clusters were being formed would
buttress the view that ellipticals and possibly other astrophysical
objects are created out of collisions.  (Nature, 10 Feb. 1994.)

PARTICLE PHYSICS WITHOUT THE SSC was the subject of
SLAC director Burton Richter's talk at this week's meeting of the
AAAS in San Francisco.  Richter said that it was inevitable that the
field would suffer a shrinkage in the number of graduate students but
that there were still several labs---LEP, HERA, Tevatron, etc.---and
plenty of topics of interest---e.g., the top quark, CP violation, deep
inelastic scattering as a probe of the proton's interior---to keep
particle physics alive.  As for the need for more powerful
accelerators, Richter suggested a scenario in which Europe would
build the next proton machine (the 14-TeV Large Hadron Collider)
while Japan and the U.S. would together build an electron-positron
collider, a 0.5-1.5 TeV machine usually referred to generically as the
Next Linear Collider (NLC).  The SSC had been a badly-managed
project, Richter asserted.  Before attempting any such large project
again, he said, a carefully prepared consensus on goals and
expectations (and costs) would have to be reached among scientists,
Congress, federal agency officials, and any prospective foreign
collaborators.

OBSERVATIONS OF SUPERCONDUCTIVITY AT 250 K are
difficult to confirm for a number of reasons.  For one thing, the
samples used by Michel Lagues in Paris were painstakingly made
atomic layer by layer, the better to control the structure, and are
therefore quite small, only 5 x 10**-8 cu.cm. This complicates the
task of making electrical contact, which limits the sensitivity of
resistance measurements.  Other problems are stability and
reproducibility; similar samples don't act alike and don't retain fixed
properties for more than a few days.  (Physics Today, Feb. 1994.)