Number 254, January 11, 1996 by Phillip F. Schewe and Ben Stein
DID NEUTRINOS KILL THE DINOSAURS? Massive collapsing stars radiate most
of their binding energy (about 10**53 ergs) in the form of neutrinos. The
rate of such collapses in our galaxy is expected to be greater, perhaps
by a large factor, than the supernova rate. John Bahcall estimates a rate
of about one collapse every 11 years in our galaxy. Stellar collapses might
not exhibit the conspicuous optical show of full-blown supernovas but can
still be potent emitters of neutrinos. According to Juan Collar, recently
of the University of South Carolina but now with the University of Paris
(collar@gps.jussieu.fr), stellar-collapse neutrinos may have played a role
in biological extinctions on Earth in past eras, notwithstanding their
very weak interactions with ordinary matter. Although stellar collapse
parameters are poorly known, Collar has ventured to calculate the effect
of a hypothetical low-dose, high- linear-energy-transfer (the energy dissipated
by a radiation per unit length through a biological sample) neutrino flux
on terrestrial animals; he suggests that collapse neutrinos may well cause
a catastrophic level of cancerous malignancy, with ensuing large- scale
loss of life, at a frequency (on the order of 100 million years) consistent
with known major extinctions on Earth. (Juan I. Collar, Physical Review
Letters, 5 February 1996; science journalists can obtain the article from
AIP Public Information, physnews@aip.org.)
JUPITER PROBE'S EARLY RESULTS: Transmitting data at a mere telegraphic
rate, the Galileo spacecraft and its detachable detector suggest that Jupiter's
atmosphere contains less water vapor and more krypton and xenon than expected.
A fuller picture will emerge as more bits arrive. (Science News, 30 December
1995.)
FRACTAL SCUM is what you get when you sprinkle a cloud of particles
on a flowing fluid. Edward Ott and his colleagues at the University of
Maryland, Johns Hopkins, and NRL observed the behavior of particles on
the surface of a tank of water slowly being drained and replenished. When
the drain is operated in a pulsed mode eddies form at the surface and the
particles arrange themselves in a fractal pattern. That is, the patterns
are self- similar at various size scales (Thomas M. Antonsen et al., Physical
Review Letters, 6 November 1995). The researchers believe that their finding
may help in the study of fluids in which flow patterns at many size scales
are important. (New Scientist, 16 December 1995.)
SWISS FACTORY TO PRODUCE Ws INSTEAD OF Zs . The Large Electron Positron
collider at CERN now moves on to higher energies (see Update 251) and the
prospective production of pairs of W bosons, the charged carriers of the
weak nuclear force. Previously LEP was a prodigious manufacturer of the
W's neutral sibling, the Z boson. With a mass almost one hundred times
that of the proton, the Z takes a lot of energy to produce and then expires
an instant later. Nevertheless, CERN physicists have observed more than
20 million Zs. By combining data from the four major experimental groups
at LEP, they arrive at a Z mass of 91.1884 GeV, with an uncertainty of
.0022 GeV. The sensitivity of the detectors is so great that lunar tidal
effects and even the impact of heavy rainfall can be discerned in the data.
(CERN Courier, November 1995.)
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