Once more, physicists have not found particles of dark matter,
this strange stuff that makes up about 83% of the matter in the
Universe. A few days ago, the XENON100 collaboration announced
at a seminar in Gran Sasso National Laboratory, in Italy, that
they have not detected any dark matter particles. One of the
most popular hypothesis suggests dark matter is made of weakly
interacting massive particles (WIMPs), that interact only
through the weak force and gravity. XENON100 is looking for this
particular kind of particles as they pass through the central
portion of 161 kilograms of liquid xenon beneath 1.4 kilometres
of rock at Gran Sasso. When colliding with the xenon nuclei, the
particles should produce electric charge and light signals. The
XENON100 researchers reported here that 100 days’ worth of data
taking turned up three events that could be due to dark matter
particles. However, the scientists expected roughly two false
positives due to interactions caused by a radioactive
contaminant in the xenon: