The CoGeNT experiment has searched for

dark matter Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not ab ...

. It uses a single

germanium Germanium is a chemical element with the symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid in the carbon group that is chemically similar to its group neighbo ...

crystal (~100 grams) as a cryogenic detector for

WIMP Wimp, WIMP, or Wimps may refer to: Science and technology * Weakly interacting massive particle, a hypothetical particle of dark matter * WIMP (computing), the "window, icon, menu, pointer" paradigm * WIMP (software bundle), the web stack of Win ...

particles. CoGeNT has operated in the Soudan Underground Laboratory since 2009.

Results

Their first announcement was an excess of events recorded after 56 days. Juan Collar, who presented the results to a conference at the University of California, was quoted: "If it's real, we're looking at a very beautiful dark-matter signal". This signal conflicts with other searches that have failed to find any evidence, such as

XENON Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

and

LUX The lux (symbol: lx) is the unit of illuminance, or luminous flux per unit area, in the International System of Units (SI). It is equal to one lumen per square metre. In photometry, this is used as a measure of the intensity, as perceived by t ...

but appears to confirm results from

DAMA Dama or DAMA may refer to: Animals *Dama gazelle (''Nanger dama'') * ''Dama'' (genus) (fallow deer) **Fallow deer (''Dama dama'') **Persian fallow deer (''Dama mesopotamica'') *Tammar wallaby or Dama wallaby (''Macropus eugenii'') Business, scie ...

. They observed an annual modulation in the event rate that could indicate light dark matter. The annual modulation has continued to be seen in 3 years of data. However more recent work has shown that the excess of events attributed to a tentative dark matter signal was in fact due to an underestimated background from surface events. After accounting for this background there is no evidence for a signal in data from the CoGeNT experiment and no tension with null results from other experiments.

References

External links

CoGeNT Dark Matter Experiment website
{{Dark matter Experiments for dark matter search