On a puzzling Signal, scientists of the Xenon1t experiment are encountered in the Views of your measurement data. On the origin of the signal appeared in the low-energy part of the energy spectrum at a few kilo-electron-volts, have the researchers still have no explanation. It is so far unknown, exotic particles and processes, which have left their traces, or to impurities in the detector, which consists of 3.5 tons of liquid Xenon? Not sure just seems that the events appear to be the long-awaited detection of Dark matter, for the Xenon1t was originally designed.
Manfred Lindinger
editor in the Department “nature and science”.
F. A. Z.
For protection against cosmic radiation in the Gran Sasso underground laboratory in the Italian region of Abruzzo, housed, should Xenon1t track from 2016 to 2018, those mysterious particles of Dark matter theoretical models that could exist. However, the search for Wimps (“Weakly Interacting Massive Particles”) is unsuccessful. And also other experiments could find no evidence that is sufficient for the existence of this uncharged mass with normal matter extremely weakly interacting particles.
From all existing Dark matter detectors is Xenon1t, the so far most sensitive and the detection of extremely rare events specialized. When a particle flies through the liquid Xenon, it creates, should it collide with a heavy noble gas core, the characteristic flashes of light, which are registered by sensitive Sensors. The lion’s share of this signals comes from cosmic rays or particles from radioactive decays in the surrounding area of the detector. The researchers want to identify an unknown particle, such as a Wimp, you have to minimize this surface as much as possible.
spirit particles from the sun
With the recent analysis of the between February 2017 and February 2018, the measured data of the international group of researchers, the scientists from Freiburg, Heidelberg, Karlsruhe, Mainz, and Münster in Germany belong, has a Surprise experienced. As they report in a peer-reviewed publication, they had registered 53 events more than the actually to be expected around 232 events. “Only due to our extreme reduction of the background rate, we were able to discover in the area of lowest energy in such a small Surplus,” says Christian Weinheimer of the University of Münster.
For the cause of this Surplus you now have different possible, for a part of spectacular explanations could be behind the Signal is still only hypothetical particles stuck, the so-called Axions. According to the researchers, resemble the gradient of the measured energy spectrum that one would expect for solar Axions. Axions were postulated in the late seventies, to be able to an inconsistency of the strong nuclear force to explain. The Axion should be unloaded, much lighter than an electron, and only weakly with normal matter to react. Myriads of them were created in the big Bang, and buzzed ever since as a Dark matter through space. These exotics are, but prove very difficult. Also in the sun, so how in all the stars and planets so the idea – Axions would arise. However, it has been found for this Thesis, as yet, no evidence.
In question also Neutrinos come but, provided the elusive elementary particles produced in radioactive decays or in the case of fusion processes in the sun possessed a magnetic Moment, which would run counter to the statements of the standard model of particle physics. “If Axions or Neutrinos could have caused the Signal, it would definitely be a Sensation,” says Weinheimer. Because both cases are a clear indication of a new physics, according to which the particle physicists since a long time.
Or just contamination?
However, there is another, more trivial explanation for the measured Excess. So it could be that low levels of radioactive Tritium in the liquid Xenon are for the Signal responsible. Tritium, a radioactive hydrogen isotope with two Extra neutrons, decays by emitting an anti-neutrino and an electron. The decay electrons are only extremely few Tritium atoms could explain the Signal. However, there is no way to determine whether, in fact, traces of Tritium in the detector material are currently.
this statement is still open, just as the other two interpretations. Because it is not identified whether or not the measured Signal but a statistical fluctuation in the measured values.