September 3rd is Carl Anderson's birthday. Anderson was an American physicist who researched cosmic rays and discovered two elementary particles. The first was the first antimatter particle, the positron. The positron is a positively charged electron. It was discovered when cosmic ray radiation traveled through a Wilson cloud chamber inside a strong magnetic field. The cosmic rays would interact with the material in the chamber and form bubbles along the path of the particles. The magnetic field would cause the path of charged particles to curve where the direction of the curve is dependent on the charge. Anderson found bubble tracks that curved the same amount as electrons, but in the opposite direction. He had found the particle predicted by Paul Dirac's quantum mechanical wave equation.
The second particle Anderson discovered was the mu meson, or muon. Working with Seth Neddermeyer and investigating cosmic rays, they discovered a charged particle with mass approximately 1/10 the mass of a proton that appeared to fit Hideki Yukawa's prediction of a particle that explained the interactions between protons and neutrons. It would later be discovered Yukawa's particle was the pi meson, or pion and Anderson/Neddermeyer's particle was the muon.
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The second particle Anderson discovered was the mu meson, or muon. Working with Seth Neddermeyer and investigating cosmic rays, they discovered a charged particle with mass approximately 1/10 the mass of a proton that appeared to fit Hideki Yukawa's prediction of a particle that explained the interactions between protons and neutrons. It would later be discovered Yukawa's particle was the pi meson, or pion and Anderson/Neddermeyer's particle was the muon.
Find out what else occurred on this day in science history.
Follow About.com Chemistry on Facebook or Twitter.
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