Happy birthday Ams-02, 10 years of hunting primordial anti-matter

The Alpha Magnetic Spectrometer 02 (Ams-02), the largest particle detector operating in space, turns 10. Hooked to the International Space Station since 2011, this ‘particle hunter’ has since analyzed over 170 billion cosmic particles and has among its main objectives the search for possible traces of primordial antimatter and dark matter signals from our galaxy. It was transported and installed on the ISS a decade ago and today the experiment successfully continues its mission. The Italian Space Agency and the National Institute of Nuclear Physics – among the main actors of the experiment – underline that the study of cosmic rays, elusive particles messengers of the energetic astrophysical phenomena of the Universe, is the main objective of Ams-02 and that this research campaign expects valuable information on the composition and evolution mechanisms of the Universe and on the origin of the dark matter that pervades our galaxy. Ams-02 was brought into orbit in May ten years ago with the penultimate Space Shuttle mission, the Sts-134 Endeavor, and among the crew members of the mission there was also the Italian astronaut of the European Space Agency Roberto Vittori, who also maneuvered the mechanical arm responsible for the transfer of Ams-02 from the Space Shuttle hold to the ISS structure. Among the members of the international collaboration responsible for Ams-02 there is therefore also Italy which, through the Italian Space Agency and the National Institute of Nuclear Physics, has played a leading role in the design of the instrument, and continues still supporting the data acquisition and analysis activities. A long life that of Ams-02 which required an unexpected and extraordinary unscheduled maintenance intervention, carried out by astronauts. The instrument, positioned outside the International Space Station, required a series of extravehicular activities (Eva) which had among the protagonists the Italian ESA astronaut, Luca Parmitano. Interventions that have made it possible to extend the activities of Ams until at least 2028. “The measurements of Ams-02 have improved the knowledge of the properties of cosmic rays and allowed a greater understanding of the origins and propagation of cosmic particles” remembers Barbara Negri, manager of the Human Flight and Scientific Experimentation Unit at the Science and Research Department of Asi. “Following the intervention carried out by Luca Parmitano, Ams-02 will be able to continue to collect data in the coming years to carry out this ambitious scientific research” Negri stresses. “In its first ten years of operation, Ams-02 revolutionized the direct measurement of cosmic ray fluxes, producing measurements of a precision never achieved before” comments Paolo Zuccon, professor at the University of Trento, member of the Infn-Tifpa and national manager of AMS-02. The Zuccon instrument, “he adds, will continue to take data until at least 2028 and thanks to its powerful magnet it will collect measurements of cosmic anti-matter particles that can open the door to new discoveries”. Consisting of a 7.5 ton detector equipped with about 300,000 sensors, Ams-02 represents an absolute frontier scientific mission, as it exploits, in a hostile environment such as space, various technologies developed on the ground inside the laboratories dedicated to particle physics. Among the main scientific objectives of the mission, the search for possible traces of primordial antimatter and dark matter signals coming from our galaxy stands out. Ams-02 measures with an accuracy never reached before the composition and abundance of cosmic rays – messengers of the Universe together with photons, neutrinos and gravitational waves – which constantly invest the Earth’s atmosphere with energies up to some TeV (tera -electronvolt), energies similar to those reached by the Large Hadron Collider (Lhc) accelerator at CERN in Geneva.Ams-02 is also a community of scientists from 16 countries around the world, a collaboration led by Samuel Ting, a professor at the Massachusetts Institute of Technology and Nobel Prize for Physics in 1976. As a demonstration, Asi and Inf point out, “the important role also played by our country, the number of Italian scientists involved in the experiment, which reaches almost a fifth of the total”. The Italian Space Agency and the National Institute of Nuclear Physics have supported the collaboration since 1995, as part of an international collaboration that includes research institutes and universities in America, Europe and Asia. The Italian researchers of the Infn offices of Bologna, Milan, Perugia, Pisa, Rome Sapienza, Rome Tor Vergata and Trento are responsible for the construction, maintenance and operations of the main on-board instruments, and participate personally in the scientific analysis of the data. collected by the tool. ASI has supported the researchers in the development and implementation phases of Ams-02 and today contributes to the support of the instrument operation and data analysis activities, carried out by the researchers of the Science and Research Department (Asi-Dsr) and at the Space Science Data Center (Asi-Ssdc). During its first ten years of life, Ams-02 collected over 170 billion cosmic particles and measured their properties to investigate several still unresolved questions of fundamental physics, such as the existence of primordial antimatter in space and the nature of dark matter. Most cosmic rays, about 99%, are made up of “ordinary” matter such as protons and helium nuclei. The rest is made up of heavy nuclei, electrons and antimatter particles. The particles of antimatter have an electric charge opposite to the ordinary one: as in the case of the proton, with positive charge, and of the antiproton, with negative charge. Thanks to its powerful magnet, Ams-02 can distinguish particles of antimatter from those of matter, and therefore accurately measure even the very rare component of antimatter in cosmic rays, in particular positrons and antiprotons. The deformations in the energy spectrum of these particles could in fact contain information on the nature of the dark matter that pervades our galaxy. The magnetic field of Ams-02 also allows us to identify heavy antimatter particles, such as anti-helium nuclei, to date never measured in space and whose observation would represent a solid discovery of antimatter of cosmological origin. With the analysis of the data collected in the first 10 years of operations, the AMS-02 collaboration has already produced a series of observations and scientific results that have been published in the most prestigious journals in the sector. The results, also accessible through the Cosmic Ray Database of the Asi-Ssdc center, are continuously used by the scientific community to understand the evolution mechanisms of the Universe, the origin of cosmic rays and their propagation.