![]() #Antimatter vs dark matter updateIt will be easier once theorists update their plots with the new AMS-02 data points on them and of course, once AMS-02 releases further information at high energy. Note they are not on the same scale and difficult to compare, but they still give some idea. the curve showing the fraction of positrons as a function of energy) would differ at high energy (the rightmost part of the plot) if the positrons come from the sum of all pulsars around or if it comes from dark matter annihilation. Here are two plots to show how different the positron fraction spectrum (i.e. If AMS-02 can prove dark matter particles can annihilate and produce pairs of electrons and positrons, it would be a complete revolution. We only detect its presence through its gravitational effects. As it stands, we observe that 26.8% of the content of the Universe comes in the form of a completely unknown type of matter called dark matter but have never been able to catch any of it. If AMS-02 does manage to show that the positron excess has a dark matter origin, the consequences would be equivalent to discovering a whole new continent. No matter how long, the whole scientific community will be waiting with great anticipation until the collaboration is confident their measurement is precise enough. How long will it take before the world gets this crucial answer from AMS-02? Prof. The data at very high energy will reveal if the observed excess in positrons comes from dark matter annihilation or from “simple” pulsars. That was the excellent news delivered at the seminar: AMS-02 will be able to measure the energy spectrum accurately enough to eventually be able to tell where the positrons come from.īut the second part of the story, the punch line everyone was waiting for, will only be delivered at a later time. The data shown clearly demonstrated the power of AMS-02. Only the first part of the story was revealed yesterday. More data is needed before the AMS-02 can get a definitive answer. The big question now is to see if the red curve will drop sharply at higher energy or not. The spectrum also extends to higher energy. Note that the AMS-02 precision exceeds the one obtained by the other experiments. The most important part of this spectrum is the high-energy part (above 100 GeV or 10 2) where the results of two previous experiments are also shown: Fermi in green and PAMELA in blue. The vertical bars indicate the size of the uncertainty. The fraction of positrons (measured with respect to the sum of electrons and positrons) captured by AMS-02 as a function of their energy is shown in red. Yesterday, we learned that AMS-02 might indeed be able to reach the needed accuracy. But this is where fewer positrons are found, making it extremely difficult to achieve the needed precision. To tell these two hypotheses apart, one needs to see exactly what happens at the high-energy end of the spectrum. There are currently two popular hypotheses: either the positrons come from pulsars or they originate from the annihilation of dark matter particles into a pair of electron and positron. Given we live in a world where matter dominates, it is not easy to explain where this excess of positrons comes from. Positrons are the antimatter of electrons. Sam Ting, one of the 1976 Nobel laureates and spokesperson of the experiment, only revealed part of the positron energy spectrum measured so far by AMS-02. After 18 years spent building the experiment and nearly two years taking data from the International Space Station, the Alpha Magnetic Spectrometer or AMS-02 collaboration showed its first results on Wednesday to a packed audience at CERN. ![]()
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