{"id":23896,"date":"2015-08-25T17:28:00","date_gmt":"2015-08-25T15:28:00","guid":{"rendered":"https:\/\/cms.zdv.uni-mainz.de\/fb08-prisma\/2015\/08\/25\/suche-nach-dunkler-materie-mit-neuer-methode\/"},"modified":"2026-02-09T10:06:13","modified_gmt":"2026-02-09T09:06:13","slug":"suche-nach-dunkler-materie-mit-neuer-methode","status":"publish","type":"post","link":"https:\/\/prisma.uni-mainz.de\/en\/2015\/08\/25\/suche-nach-dunkler-materie-mit-neuer-methode\/","title":{"rendered":"Searching for dark matter with a new method"},"content":{"rendered":"\n<\/jgu-base-pageheader><\/jgu-base-heading>\n\n
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Dark matter particles should interact with atomic nuclei – according to current theories. While the search for this in many experiments has so far been unsuccessful, the DAMA\/LIBRA collaboration claims to have discovered a signal from dark matter. The scientists of the XENON collaboration have now searched their data for interactions of dark matter with electrons in the atomic shell. The analysis revealed no signal above the very low background noise. This renders an explanation of the appeal by models that assume an interaction of dark matter only with electrons obsolete. [Science, 21.08.2015; Physical Review Letters, accepted] <\/p>\n\n\n\n

From a theoretical point of view, weakly interacting heavy particles, known as WIMPs, are probably the preferred candidates for dark matter. In experiments, they should occasionally make themselves known through collisions with atomic nuclei of the detector material. “Our XENON100 detector is one of the most sensitive in the world, yet we have not found any dark matter with it,” says Uwe Oberlack from the University of Mainz. The motion of the Earth around the Sun, which moves through the Milky Way’s dark matter halo on its orbit around the center of the Milky Way, should continue to lead to a seasonal modulation of the signal: More events are expected in summer, fewer in winter. Although the DAMA\/LIBRA experiment has measured such a modulation over a period of 14 years with its sodium iodide detector, interpreting this as a WIMP signal is in appeal to the results of several other experiments. <\/p>\n\n\n\n

Because DAMA\/LIBRA cannot distinguish between scattering from the atomic nucleus or the electrons of the atomic shell, lighter particles that only scatter from electrons would be a possible explanation for all the data. This is why the scientists in the XENON collaboration have now used new analytical methods to look for instructions in their data and published their results in two papers. The XENON100 detector (see Figure 1) uses 62 kg of liquid xenon as a detection medium and measures the tiny charge and light signals that are expected in the rare collisions of dark matter particles with xenon atoms. In contrast to DAMA\/LIBRA, XENON100 can distinguish well between scattering from atomic nuclei and from electrons. The experiment is housed in the Italian Gran Sasso underground laboratory (LNGS), where 1400 m of rock shields the interfering cosmic radiation. In order to exclude false signals due to natural radioactivity in the vicinity of the detector, the detector is shielded by layers of xenon, copper, polyethylene, lead and water. As a result, the rate of interfering background signals is more than 100 times lower than with DAMA\/LIBRA and even lower than the amplitude of the seasonal modulation observed there. <\/p>\n\n\n\n

Nevertheless, the XENON collaboration also examined their data on scattering from electrons in the atomic shell for temporal variations. The decisive factor here was that the detector itself was operated stably during the entire measurement period. This has now been demonstrated for the first time ever for a xenon detector. “The search for possible temporal variations revealed no significant modulation over periods of up to 500 days – in appeal to the DAMA\/LIBRA observation,” says Christian Weinheimer from the University of M\u00fcnster, summarizing the results of the new analysis. <\/p>\n\n\n\n

The XENON researchers have also calculated, under various assumptions, what the signal from DAMA\/LIBRA would look like in their detector if it had been caused by dark matter particles scattered by electrons. The comparison of this expectation with the XENON100 data from a period of 70 days around the maximum of the seasonal modulation is clear: no signal, just the expected background (see Figure 2). The calculated upper limit for the probability of such an interaction is so low that the DAMA\/LIBRA signal can be completely excluded. <\/p>\n\n\n\n

“Thus, none of the investigated models that could bring the DAMA\/LIBRA data into agreement with the results of other experiments stands up to the new verification by the XENON100 experiment,” summarizes Manfred Lindner from the KPI for Nuclear Physics, “Consequently, the DAMA\/LIBRA result cannot be explained by dark matter that only scatters on electrons.”<\/p>\n\n\n\n

As the XENON100 detector has reached the limit of its sensitivity, the collaboration is currently installing a detector that is 100 times more sensitive. This instrument, XENON1T, will open a completely new chapter in the search for dark matter at the end of the year. <\/p>\n\n\n\n

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The Max Planck Institutes for Nuclear Physics (MPIK) in Heidelberg, the Johannes Gutenberg University Mainz and the University of M\u00fcnster are involved in the international XENON collaboration from Germany. All institutes are involved in data collection and analysis. In XENON100, the MPIK is also responsible for measuring and suppressing the extremely low radioactive background in the xenon gas using very sensitive instruments. In XENON1T, the MPIK is responsible for the selection and control of detector materials with extremely low radioactivity, the development and testing of the light sensors and the xenon target. For XENON100, the group at the University of Mainz was responsible for the electrodes of the inner detector and was significantly involved in the data readout system. For XENON1T, the group is responsible for the muon detector. The group is also involved in the innovative xenon storage system ReStoX and the inner detector. The researchers at the University of M\u00fcnster are involved in both XENON detectors and make important contributions to the calibration. For the upcoming XENON1T experiment, the M\u00fcnster group is responsible for the purity of the xenon and has developed the purification circuit and a unique cryogenic distillation system. <\/p>\n<\/div>\n\n\n\n

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Dark matter particles should interact with atomic nuclei – according to current theories. While the search for this in many experiments has so far been unsuccessful, the DAMA\/LIBRA collaboration claims to have discovered a signal from dark matter. The scientists of the XENON collaboration have now searched their data for interactions of dark matter with … Continued<\/a><\/p>\n","protected":false},"author":554,"featured_media":19351,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[105],"tags":[],"class_list":["post-23896","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-press-release"],"primary_category":{"id":105,"name":"Press release","slug":"press-release","parent":0,"breadcrumb":"Press release"},"media":{},"image":{"url":"https:\/\/cms.zdv.uni-mainz.de\/fb08-prisma\/wp-content\/uploads\/sites\/255\/2025\/10\/08_physik_darkmatter_25_08_2015.png","credit":""},"index":"25.08.2015","assigned_date":"","external_link":"","_links":{"self":[{"href":"https:\/\/prisma.uni-mainz.de\/en\/wp-json\/wp\/v2\/posts\/23896","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/prisma.uni-mainz.de\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/prisma.uni-mainz.de\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/prisma.uni-mainz.de\/en\/wp-json\/wp\/v2\/users\/554"}],"replies":[{"embeddable":true,"href":"https:\/\/prisma.uni-mainz.de\/en\/wp-json\/wp\/v2\/comments?post=23896"}],"version-history":[{"count":2,"href":"https:\/\/prisma.uni-mainz.de\/en\/wp-json\/wp\/v2\/posts\/23896\/revisions"}],"predecessor-version":[{"id":28865,"href":"https:\/\/prisma.uni-mainz.de\/en\/wp-json\/wp\/v2\/posts\/23896\/revisions\/28865"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/prisma.uni-mainz.de\/en\/wp-json\/wp\/v2\/media\/19351"}],"wp:attachment":[{"href":"https:\/\/prisma.uni-mainz.de\/en\/wp-json\/wp\/v2\/media?parent=23896"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/prisma.uni-mainz.de\/en\/wp-json\/wp\/v2\/categories?post=23896"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/prisma.uni-mainz.de\/en\/wp-json\/wp\/v2\/tags?post=23896"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}