[Tell It Right]

One day I’ll take time to learn more detail about experiments such as these and with particle accelerators. One thing I’m interested in is exactly how they do measurements to not only detect the existence of things like positrons, but also can track their movement.

[Lonesome in Massachussets]

Antiparticles were first discovered in cloud chambers. The antielectron was deflected the wrong/opposite way in a magnetic field. One could infer the mass/charge ratio from the radius of curvature. It had the same mass/charge ratio as the electron, but the wrong charge. Discovery photograph from wikipedia:

Cloud chamber photograph of the first positron ever observed. The thick horizontal line is a lead plate. The positron entered the cloud chamber in the lower left, was slowed down by the lead plane, and curved to the upper left. The curvature of the path is caused by an applied magnetic field that acts perpendicular to the image plane. The higher energy of the entering positron resulted in lower curvature of its path. Original caption: A 63 million volt positron (Hρ = 2.1×105 gauss-cm) passing through a 6 mm lead plate and emerging as a 23 million volt positron (Hρ = 7.5×104 gauss-cm). The length of this latter path is at least ten times greater than the possible length of a proton path of this curvature.