Nikhef researchers refute claim of dark matter detection

21 August 2015

Researchers of the XENON collaboration, which also includes researchers of FOM Institute for Subatomic Physics (Nikhef), have refuted a long-standing claim of dark matter detection. Their findings have been published in this week’s edition of Science.

A new XENON100 analysis, published in Science this week, refutes a long-standing claim of dark matter detection. Dark matter is an abundant but unseen matter in the universe considered largely responsible for the gravitational force that keeps the Milky Way galaxy together. According to most current theoretical models, the hypothetical dark matter particles interact with atomic nuclei. However, such interactions have not been detected to date. The scientists of the XENON collaboration have developed novel analysis techniques to search for the first time in the data of the XENON100 detector for interactions of dark matter with electrons of the atomic shell. The analysis did not yield any signal above the very low background, further constraining the properties of dark matter.

DAMA/LIBRA controversy revived

This finding is of particular importance with respect to the results of the rival DAMA/LIBRA collaboration, which claims the detection of a dark matter signal with high significance. DAMA/LIBRA cannot distinguish between dark matter interactions with electrons or atomic nuclei. Searches by other experiments for interactions with atomic nuclei were not successful. Many theoretical models, which try to explain the observed discrepancy by assuming that dark matter particles interact only with electrons, are now excluded by the latest findings of the XENON collaboration. The new results should therefore revive the controversy about alternative explanations of the DAMA/LIBRA signal.

Awaiting even better detectors

Together with 17 other institutes, Nikhef is part of the XENON collaboration. The consortium is currently completing the XENON1T experiment, an experiment 20 times more massive than XENON100, which will become the world’s most sensitive dark matter detector when it starts recording data later this year. To search further and fully characterize dark matter particles, the collaboration is designing the even larger XENONnT experiment to become operational in 2019. All XENON experiments operate at the Gran Sasso underground laboratory in Italy.

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