Number 41, July 17, 1991 by Phillip F. Schewe and Ben Stein|
HYDROGEN ATOMS HAVE BEEN MADE by the overlapping of beams of free electrons and protons in the presence of laser radiation. In the beam environment the two particles may meet but seldom mate because there isn't enough time for the electron to fall into the kind of lower orbit needed for a lasting marriage. Now groups at Heidelberg University (Germany) and at the University of Western Ontario (Canada) report (both in the 1 July issue of Physical Review Letters) the use of laser light to foster a fast de-excitation, leading to the formation of stable atoms in well-defined energy states. Farook Yousif of the University of Western Ontario believes the process might be used to create anti-hydrogen. (Science News, 13 July 1991.)
A THIRD EINSTEIN RING , a hundred times brighter than either of the previously discovered rings, is puzzling astronomers. An Einstein ring is a gravitational lens effect caused by the distortion of the image of a distant celestial body by a massive object aligned in front of it in such a way as to produce an elliptical ring of fairly uniform brightness. The Australian and British astronomers who discovered the object believe the ring's abnormally high intensity arises from either an extremely bright source or an unusually large amplification by the lensing object, requiring an extremely high degree of alignment. (Nature, 11 July 1991.)
EVIDENCE FOR THE 17-KEV NEUTRINO has been seen in an electron-capture experiment. A team of scientists at Boskovic Institute in Zagreb, Yugoslavia reports in the 29 July Physical Review Letters (preliminary results appeared at a nuclear physics meeting in December 1990) that the spectrum of gamma photons radiated by electrons as they are captured by germanium-71 nuclei suggests that in 1.6% of the capture events, a 17.2-keV neutrino is being emitted. This particular nuclear reaction, called internal bremsstrahlung in electron capture (IBEC), is a sort of beta decay in reverse; Eric Norman at LBL used IBEC reactions in iron-55 (as well as beta-decay reactions in carbon-14) to find evidence for a 17-keV neutrino.
FULLERENES IN THE ORDINARY SOOT produced in hydrocarbon combustion have been detected by scientists at MIT who studied the spectroscopy of soot from burning benzene flames. They found a similarity with known carbon-60 and carbon-70 spectra. This finding may lead to an alternative method for producing fullerenes, and it may also provide insight into the formation of crystals from hydrocarbon flames. (Nature, 11 July 1991.)
PRODUCING CRYSTALS IN HIGH GRAVITY reduces impurities in certain materials, contrary to scientists' original expectations. Using fast-spinning centrifuges which create artificial high-gravity fields, Soviet and French scientists have grown metal alloys with fewer imperfections (and with different microstructures) than those prepared under normal conditions. The pure materials, however, are only produced at certain "magical" values of the gravitational field strength. Scientists believe that high-gravity manufacturing processes may bring about purer semiconductors and alloys and may even rival low-gravity space labs as a means of growing purer crystals. (Science, 5 July.)