An international team of researchers led by the Max Planck Institute of Quantum Optics (MPQ) in Garching has actually nonetheless combined matter and antimatter into curious hybrid atoms of helium that remain steady for short durations of time. Now the researchers from Italy, Hungary, and Germany have actually submerged the strange atoms into liquid helium and cooled it down to temperature levels close to outright zero– where the helium changes into a so-called superfluid state.
” Experiments on antimatter are especially exciting with concerns to the basic laws of physics.”– Masaki Hori.
Antiprotonic helium atom suspended in liquid helium in the superfluid state. Now the researchers from Italy, Hungary, and Germany have submerged the unusual atoms into liquid helium and cooled it down to temperature levels close to absolute no– where the helium changes into a so-called superfluid state.
The outcomes of the experiments carried out at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland amazed the researchers because of the sensitive and precise way that the antimatter-matter hybrid atoms reacted to laser light regardless of the dense liquid that surrounded the atoms.
” Experiments on antimatter are particularly interesting with concerns to the fundamental laws of physics,” says Masaki Hori, the team leader. The Standard Model of particle physics– the basis of researchers present understanding of the structure of the universe and the forces acting within it– requires that particles and their antiparticles vary in the sign of their electric charge. An antiproton– the counterpart of the positively charged proton, a building block of atomic nuclei– carries an unfavorable charge. According to the Standard Model the other residential or commercial properties are identical. “In our past experiments, we have discovered no evidence that the masses of protons and antiprotons vary in the slightest,” keeps in mind Hori. “If any such difference could be discovered, nevertheless small, it would shake the structures of our current view of the world.”.
Research leader Masaki Hori at the ASACUSA experiment in CERN. Credit: CERN.
“To do this, atoms of antimatter have actually been magnetically levitated in vacuum chambers for spectroscopic measurements. Other experiments have restricted antiprotons in ion traps made of electrical and magnetic fields,” Hori explains. “Our group has formerly used this hybrid helium atom to precisely compare the masses of electrons and antiprotons.”.
With his groups newest findings, nevertheless, the Garching physicist has led the way for a different application of antimatter by optical spectroscopy of antiprotonic helium atoms in a superfluid environment.
Electron out, antiproton in.
To develop the exotic helium atoms including antiprotons, the scientists utilized the Antiproton Decelerator at CERN– a worldwide distinct facility that slows down the antimatter particles developed in collisions of energetic protons. The sluggish speed of the antiprotons makes them perfect for experiments such as those conducted by Horis team. The scientists blended the sluggish antiprotons with liquid helium cooled to a temperature of a few degrees above absolute zero, or minus 273 degrees Celsius, trapping a small part of the antiprotons in atoms of helium. The antiproton replaced among the 2 electrons that normally surround a helium atomic nucleus– forming a structure that remained stable enough time to be studied spectroscopically.
Picture of the quadrupole triplet lens utilized to focus the antiproton beam into a helium target. Credit: CERN.
” Until now, it was believed that antimatter atoms embedded in liquids might not be investigated by high-resolution spectroscopy utilizing laser beams,” Hori reports. These lines are images of resonances in which the energy absorbed from the laser beam excites the atoms. The exact position of the resonance line on the frequency scale as well as the shape expose the residential or commercial properties of the atom under examination– and the forces acting on the antiparticle.
Remarkably slim line at 2.2 Kelvin.
In a series of experiments, the scientists took a spectroscopic look at the antiprotonic helium atoms at different temperatures. To do this, they irradiated the liquid helium with light from a titanium-sapphire laser, which delighted 2 particular resonances of the antiprotonic atoms at two various frequencies.
The surprising discovery: “If the temperature dropped listed below the vital temperature level of 2.2 Kelvin– 2.2 degrees Celsius above absolute no– at which helium gets in a superfluid state, the shape of the spectral lines suddenly altered,” reports Anna Sótér, who was the principal PhD student of the MPQ group in this project and just recently promoted as assistant teacher of ETH Zürich. “The lines that were very broad at higher temperatures became narrow.”.
The quantum physical phenomenon is normal of helium at exceptionally low temperature levels. “How the striking modification in the spectral lines of the antiproton comes about in such an environment and what takes place physically in the process is something we do not understand yet,” states Hori.
However the possibilities provided by the result are far-reaching. This is since the narrowing of the resonance lines is so extreme that when thrilled with light, the so-called hyperfine structure can be solved, the researchers report in a publication in Nature. The hyperfine structure is a consequence of the mutual influence of the electron and the antiproton in the atom. This shows that scientists could create in superfluid helium other hybrid helium atoms with different antimatter and unique particles to study in information their reaction to laser light and measure their masses. An example of this is pionic helium atoms that were recently studied by laser spectroscopy at the 590 megaelectron volt cyclotron facility of Paul Scherrer Institute in Villingen, Switzerland.
Searching for particles in cosmic radiation.
The sharp spectral lines might also be handy in identifying antiprotons and antideuterons in cosmic radiation. Scientists have actually been on the trail of these for several years, for example with experiments on board the International Space Station (ISS). Soon, scientists will also release a test balloon over Antarctica– with an instrument on board that can detect antiprotons and antideuterons that might exist at very high altitudes in the atmosphere.
Masaki Hori speculates: “Detectors with superfluid helium might support future experiments and might appropriate for recording and analyzing antiparticles from space. Various technical difficulties must be gotten rid of, nevertheless, prior to such approaches become complementary to existing ones.”.
This would perhaps help resolve another excellent secret: the concern of the nature of dark matter– a hitherto unidentified and ominous kind of matter that is invisible but apparently represent a large part of the mass in the universe. In some theories, it is believed that when dark matter communicates in the halo of our Galaxy, antiprotons and antideuterons may be produced that could then be carried to the earth. Antimatter, of all things, could shed light on this darkness.
For more on this research study, see Unexpected Behavior of Hybrid Matter– Antimatter Atoms in Superfluid Helium Surprises Physicists.
Reference: “High-resolution laser resonances of antiprotonic helium in superfluid 4He” by Anna Sótér, Hossein Aghai-Khozani, Dániel Barna, Andreas Dax, Luca Venturelli and Masaki Hori, 16 March 2022, Nature.DOI: 10.1038/ s41586-022-04440-7.
Antiprotonic helium atom suspended in liquid helium in the superfluid state. The antiproton is safeguarded by the electron shell of the helium atom therefore avoids instant annihilation. Credit: Christoph Hohmann (LMU München/ MCQST).
A team of researchers at CERN led by MPQ physicist Masaki Hori discovered that a hybrid antimatter-matter atom behaves in an unanticipated way when immersed in superfluid helium. The result might open a brand-new method for antimatter to be used to examine the properties of condensed matter, or to look for antimatter in cosmic rays.
“Our group has actually formerly used this hybrid helium atom to exactly compare the masses of electrons and antiprotons.”.
To create the exotic helium atoms including antiprotons, the scientists utilized the Antiproton Decelerator at CERN– a globally special facility that slows down the antimatter particles created in accidents of energetic protons. The scientists blended the sluggish antiprotons with liquid helium cooled to a temperature of a few degrees above absolute no, or minus 273 degrees Celsius, trapping a little part of the antiprotons in atoms of helium.
