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THE HISTORICAL
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“Bite-Size Bits of Local, National, and Global History”
Pasadena in Los Angeles County, California — The American West (Pacific Coastal)
 

The First Known Antiparticle

Historic Physics Site

 
 
First Known Antiparticle Marker image. Click for full size.
Photographed by Craig Baker, September 29, 2018
1. First Known Antiparticle Marker
Inscription.
Near this site, in August 1932, Carl David Anderson photographed the track of a cosmic ray particle in his cloud chamber. He identified this particle as the positron — the first known antiparticle.

Historic Physics Site, Register of Historic Sites, American Physical Society.
 
Erected by American Physical Society.
 
Topics. This historical marker is listed in these topic lists: EducationScience & Medicine.
 
Location. 34° 8.194′ N, 118° 7.55′ W. Marker is in Pasadena, California, in Los Angeles County. It can be reached from California Boulevard 0.1 miles east of Wilson Avenue. Located on the Cal Tech campus, at the north-east corner of the Bridge Labs Buildings. Touch for map. Marker is at or near this postal address: 1200 E California Boulevard, Pasadena CA 91125, United States of America. Touch for directions.

Regionally, this marker is in Greater Los Angeles and in the Transverse Ranges. It is also on the American Pacific Coast. Globally, it is in North America, on the Ring of Fire, in the Pacific Rim, in the Western Hemisphere, in the Western
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World, and in the Anglosphere. Historically, it finds itself in what was once New Spain and also Mexico’s Alta California.

Other nearby markers. At least 8 other markers are within walking distance of this marker: Karman Laboratory of Fluid Dynamics and Jet Propulsion (about 300 feet away, measured in a direct line); Throop Memorial Garden (about 300 feet away); William Morris Davis, 1850-1930 (about 300 feet away); Iris Garden (about 400 feet away); Hameetman Center (about 700 feet away); Beckman pH Meter (approx. 0.2 miles away); Tournament Park (approx. Ό mile away); Hale Solar Laboratory (approx. 0.3 miles away). Touch for a list and map of all markers in Pasadena.
 
First Known Antiparticle Marker image. Click for full size.
Photographed by Craig Baker, September 29, 2018
2. First Known Antiparticle Marker
Nearby Sign image. Click for full size.
Photographed by Craig Baker, September 29, 2018
3. Nearby Sign
Near the seismology lab at Wilson & California Ave.
 
 
Credits. This page was last revised on January 30, 2023. It was originally submitted on October 2, 2018, by Craig Baker of Sylmar, California. This page has been viewed 416 times since then and 15 times this year. Photos:   1, 2, 3. submitted on October 2, 2018, by Craig Baker of Sylmar, California. • Andrew Ruppenstein was the editor who published this page.
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Jul. 5, 2026