To the best of my knowledge, as of my 2023 understanding, no atoms of antimatter elements, including antihelium or other antimatter elements, have been found or observed in nature. Antimatter particles are extremely rare in the observable universe, and their production and storage present significant challenges.
Antimatter is composed of antiparticles, which have the same mass as their corresponding particles but opposite charge. For example, antihelium would consist of two antiprotons and two antielectrons (positrons).
In controlled laboratory settings, scientists have been able to produce and study small amounts of antimatter particles, including antihydrogen (an antiproton and a positron). These experiments are typically conducted in specialized particle accelerators or storage rings.
The primary method for creating antimatter in nature is through high-energy processes such as particle collisions. For instance, high-energy cosmic rays can interact with matter in space, leading to the creation of antimatter particles. However, antimatter is highly reactive and tends to annihilate upon contact with matter, converting into pure energy. Consequently, detecting and observing significant amounts of naturally occurring antimatter is challenging due to its scarcity and short lifespan.
While no significant natural sources of antimatter have been identified, ongoing research continues to explore the properties and production of antimatter for scientific investigation and potential future applications.