The ALICE experiment at the Large Hadron Collider (LHC) at CERN has been designed to compare the matter to antimatter. The scientists were successful in making a precise measurement of the difference between ratios of electric charge and mass of light nuclei and antinuclei. The results are published in Nature Physics.
The new research confirms to an unprecedented precision for light nuclei a fundamental symmetry of nature. The experiment is based on the ALICE's abilities to track and identify particles that were produced in environments of high-energy heavy-ion collisions at the LHC.
The ALICE collaboration has measured so far the difference between mass-to-charge ratios for deuterons and antideuterons. According to scientists, deuterons are particles composed of a proton, or hydrogen nucleuses, with an additional neutron, while their opposite antimatter particles are the antideuterons. The scientists were also able to measure the differences for helium-3 nuclei (two protons plus a neutron) and antihelium-3 nuclei.
Previous measurements at CERN made recently by the BASE experiment, have already been compared at high precision the same properties of protons and antiprotons. This new study by ALICE takes the research a step further and it proves the theory stating that it is possible to exist some subtle differences between the way that protons and neutrons in nuclei bind together compared with the way how their antiparticle counterparts form into antinuclei.
This theory stipulating the symmetry of nature implies that all of the laws of physics would be the same under the simultaneous reversal of charges and reflection of spatial coordinates. The results of this new study come exactly 50 years after the discovery of the antideuteron. The research at CERN and in the U.S. comes to improve on existing measurement results by a factor of 10-100.
According to CERN Director-General Rolf Heuer, these measurements by BASE and ALICE experiments have been conducted at the lowest and highest energies available at the Large Hadron Collider facilities, showing "the diversity in the laboratory's research program".
ALICE spokesperson, Paolo Gibellino, added that the high precision of ALICE's time-of-flight detector makes possible for scientists to determine the arrival time of particles and antiparticles with a resolution of 80 picoseconds. This feature associated with the energy-loss measurement provided by ALICE's time projection chamber allows researchers to measure "a clear signal for deuterons/antideuterons and helium-3/antihelium-3 over a wide range of momentum".
