Physics Update


The American Institute of Physics

Bulletin of Physics News

ULTRAHIGH ENERGY COSMIC RAYS, those with energies above 10**19 eV, pose a problem for astrophysicists. The rays can't originate from too far out in the cosmos, otherwise interactions with photons in the cosmic microwave background would have cooled down the cosmic rays to lower energies. Do they, as some theorists propose,come from the decay of superheavy primordial particles? (See the item in New Scientist, 26 August 1995) Addressing the subject of whether the high energy cosmic rays come from relatively nearby, a new study of the arrival directions of 143 cosmic ray events with energies of higher than 2x10**19 eV reveals a nonuniformity; the rays seem to arrive preferentially from the "supergalactic plane," which, according to Todor Stanev of the Bartol Insitute (temporary address in Italy: is defined by the agglomeration of nearby galaxies (redshift less than 0.03); in the northern hemisphere this wold mean roughly the Virgo cluster of galaxies. This finding supports the notion that the highest energy cosmic rays originate outside our own galaxy, perhaps in relatively neraby radio glaxies. (Todor Stanev et al., upcoming article in Physical Review Letters; Journalists: for a copy of the article, contact AIP Public Informatin at

ANTIMATTER TRAP Theodor Hansch and his colleagues at the Max Planck Institute and the Unviersity of Munich in Germany have for the first time trapped simultaneously electrons and positively charged ions in the same small region of space. The researchers consider this to be "an important step towards the synthesis of antihydrogen." Making antihydrogen -- consisting of a positron in orbit around an antiproton -- would allow scientists to test the laws of physics all over again, this time with antimatter. The hybrid Munich apparatus consists of a Penning trap (a homogeneous static magnetic field and a static electric quadrupole field) for confining the ions and a Paul trap (the static electric quadrupole plus an oscillating electric quadrupole field) for confining the electrons. As practice for making antihydrogen, the German physiscists intend to stimulate the generation of ordinary hydrogen from electrons and protons using a carbon dioxide laser. (J. Walz et al., upcoming article in Physical Review Letters; contact

A LASER IN THE SKY has been detected by the aricraft-mounted Kuiper Observatory. Although astronomers have previously detected celestial masers -- coherent microwave emissions coming from gas clouds surrounding certain stars -- the higher energy laser equivalent has been difficult to spot until now. The laser emission (at a near IR wavelength of 169 microns) originates at a star about 4000 light years away, probably from hydrogen in a circumstellar disk. (Science, 8 September 1995) (Compiled by Mark Elowitz)