No, antimatter was not invented by any specific country, including the United States. The concept of antimatter originated from theoretical physics, specifically from the work of Paul Dirac, a British physicist, in the late 1920s. Dirac's equations predicted the existence of antiparticles, which have the same mass as regular particles but opposite charge.
Experimental confirmation of antimatter came later. In 1932, Carl D. Anderson, an American physicist, observed the first evidence of antimatter when he discovered the positron, the antiparticle of the electron, while studying cosmic rays. Anderson's discovery earned him the Nobel Prize in Physics in 1936.
Since then, antimatter has been extensively studied and produced in various countries around the world. Research facilities and laboratories in different countries, including the United States, have contributed to our understanding of antimatter properties, behavior, and potential applications. Today, antimatter is generated and studied at facilities such as CERN (European Organization for Nuclear Research) in Switzerland and Fermilab in the United States, among others.
While the United States has made significant contributions to antimatter research, it is important to recognize that the discovery and study of antimatter are the result of international collaboration and the collective efforts of scientists from around the world.