How are galaxies born, and what holds them together? A lot of astronomers think that dark matter is crucial to the universe. It hasn’t been feasible to show directly that dark matter is present, however, at this time. A team headed by the Technical University of Munich (TUM) measured the survival rate of antihelium nuclei from the depths of the universe for the first time, an essential requirement to the indirect hunt for dark matter.
A lot of evidence indicates dark material is present. How galaxies move around in galactic clusters or just how quickly stars circle the middle of a galaxy lead to calculations which suggest that there should be much more mass present compared to what we see. About 85 % of our Milky Way for instance consists of a substance which isn’t apparent and which can only be detected depending on its gravitational effects. It’s still not feasible to prove the presence of this material this time.
A number of theoretical models of dark matter anticipate it might be made up of particles that weakly interact with one another. This produces antihelium-3 nuclei that include 2 antiprotons as well as one antineutron. These nuclei can also be produced in high energy collisions between common matter and cosmic radiation, like helium and hydrogen, but with energies different from all those anticipated in the interaction of dark matter particles.
In both procedures, the antiparticles originate from the depths of the universe, many tens of thousands of light years from us. A portion of them will make its way in our path following their creation. Just how a number of these molecules endure unscathed and get to the vicinity of Earth as signs of the development procedure decides the transparency of the Milky Way for antihelium nuclei. Scientists have been able just to approximate this value up to recently. An enhanced approximation of transparency, a unit of measure for the amount as well as energies of antinuclei, is going to be crucial in interpreting upcoming antihelium measurements.
LHC particle accelerator as antimatter factory
Researchers from the ALICE collaboration have now performed measurements which have allowed them to figure out the transparency much more exactly for the very first time. ALICE stands for A big Ion Collider Experiment and it is among the biggest experiments on the planet to investigate physics on the smallest length scales. ALICE is an element of Large Hadron Collider (LHC) at CERN.
LHC is able to easily create huge quantities of gentle antinuclei, like antihelium. To do lead, protons, and this atoms are each put on a collision course. Collisions produce particle showers that are subsequently captured by the detector of the ALICE test. Scientists could subsequently find the antihelium-3 nuclei which have developed thanks to a number of subsystems of the detector and follow their trails in the detector material. This enables us to compute the likelihood that an antihelium-3 nucleus is going to interact as well as vanish with the detector material. Experts from the TUM and the Excellence Cluster Origins considerably contributed to the evaluation of experimental data.
Galaxy transparent for antinuclei
Scientists were able to transmit results from the ALICE experiment to the entire galaxy using simulations. The result: About 50 % of the antihelium-3 nuclei, which were anticipated to be created in the interaction of dark matter particles, would reach Earth in the vicinity. Thus, our Milky Way is fifty % permeable for those antinuclei. For antinuclei produced in collisions between cosmic light and the interstellar medium, the ensuing transparency ranges from 25 to 90 percent with increasing antihelium-3 momentum. These antinuclei, however, can be distinguished from those created by dark matter based on their higher power.
What this means is that antihelium nuclei in the Milky Way not merely should travel lengthy distances, but tend to work in succeeding tests as crucial informants: Based on the number of antinuclei arrive on Earth and with what energies, the origin of these well-traveled messengers could be translated by the brand new computations as dark matter or cosmic rays.
Reference for future antinuclei measurements in space
“This is an excellent illustration of an inter-disciplinary analysis which shows how measurements at particle accelerators can be directly associated together with the research of cosmic rays in space,” says Origins scientist Prof. Laura Fabbietti of the TUM School of Natural Sciences. The results of the ALICE experiment at LHC are of great significance for the hunt for antimatter in Space using the AMS-02 module (Alpha Magnetic Spectrometer) on the International space Station (ISS). The Gaps balloon test will even look at new cosmic rays for antihelium-3 in the Arctic beginning in 2025.
Reference: “Measurement of anti-3He nuclei absorption in matter and impact on their propagation in the Galaxy” by The ALICE Collaboration, 12 December 2022, Nature Physics.
DOI: 10.1038/s41567-022-01804-8
The work on the antihelium-3 interaction, led by Prof. Dr. Laura Fabbietti, involved research groups led by Prof. Dr. Alejandro Ibarra at TUM and Dr. Andrew Strong at the Max Planck Institute for Extraterrestrial Physics. This research has been funded by the Federal Ministry of Education and Research, and also by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through the Excellence Cluster ORIGINS, EXC 2094 – 390783311 and the Collaborative Research Center SFB1258.
