快猫短视频

THEY may be WIMPs, but then again maybe not. Flashes of light deep beneath
the surface of the Earth are puzzling particle physicists on the hunt for dark
matter.

Astronomers know that galaxies must be about ten times as massive as they
appear. Without some form of dark matter to serve as a gravitational glue,
galaxies should simply fly apart. One candidate for this invisible mass is the
WIMP, a weakly interacting massive particle
(快猫短视频, 16 January, p 24).

WIMPS are hard to detect because they seldom interact with regular matter,
usually passing through the Earth unhindered. But occasionally, a WIMP might
just strike an atom or a subatomic particle.

Neil Spooner and his colleagues at the University of Sheffield have been
trying to detect the flashes of light that happen when a WIMP slams into an
atom. Their detector, submerged in 200 000 litres of water, deep in a Yorkshire
mine to protect it from distracting flashes caused by cosmic rays, has spotted a
handful of flashes each day that don鈥檛 fit other sources of background
鈥渘辞颈蝉别鈥�.

鈥淭hese are what we call our anomalous events,鈥� says Spooner. 鈥淥ur feeling is
that it鈥檚 some sort of background.鈥� But so far, he reckons, no model of the sort
of background flashes expected in the mine predicts such events. 鈥淚t鈥檚 something
蝉迟谤补苍驳别.鈥�

Unfortunately, the characteristics of the flashes don鈥檛 quite match what鈥檚
expected of a WIMP collision either, so the anomalous events leave the
physicists scratching their heads. More advanced detectors are in the works but
until they鈥檙e up and running, we remain in the dark.