Cesar Lattes: the Brazilian physicist who discovered - and produced - pions

Image Credit: PICRYL

Physics enthusiasts started wondering about a physicists that was not well known in the realm of contemporary physics, as his image was splashed across the internet with a Google doodle on July 11, 2024.

He was born 100 year ago on July 11, 1924, in Brazil.  

César Lattes, the physicist in question, was a brilliant Brazilian physicist who played a key role in the discovery of the pion, a fundamental subatomic particle. 

Not only did he discover it using cosmic rays that fell on photographic plates in the Bolivian Andes, but also became instrumental in producing pions artificially in a lab.

The height of the mountain region, light-pollution-free atmosphere and relative quiet may have provided Lattes and his team with a perfect geographic region, conducive for an experiment of this kind. 

He was born in Curitiba, Brazil, Lattes graduated from the University of São Paulo in 1943 with a degree in both mathematics and physics. Thanks to the association with the talented physicists of his day,  like Gleb Wataghin and Giuseppe Occhialini, who in turn  nurtured his scientific curiosity, he made great strides in his chosen field that led to a major breakthrough.

 

Pions are sub-atomic particles known as mesons. They consist of a quark and an an antiquark. There are three kinds of pions, depending on its charge - or absence of it. They are π-plus, π-minus and π-neutral.

The illustrious career of Lattes has three distinct phases that evolved as follows:

• Pion Discovery: At a young age (24), Lattes teamed up with Cecil Frank Powell and Giuseppe Occhialini. Together, they used a clever technique – analyzing photographic plates exposed to cosmic rays in the Bolivian Andes. This innovative approach led to the discovery of the pion in 1947.

• Artificial Pion Production: Lattes didn't stop there. In 1948, he collaborated with Eugene Gardner at UC Berkeley. They successfully produced pions in a laboratory setting by bombarding carbon nuclei with alpha particles - positively charged helium nuclei. This confirmed the existence of pions and opened doors to further research in controlled environments.

• Legacy: Lattes is considered one of the most distinguished physicists in Brazil. His work on the pion was a major breakthrough in understanding nuclear forces and paved the way for further discoveries in particle physics. Beyond research, he actively championed scientific development in Brazil. He was instrumental in the creation of the Brazilian National Research Council (CNPq), which continues to support scientific research in the country.