Answer: positron

AnswerCrossword Clue
POSITRON

Subatomic particle

POSITRON

Certain antiparticle

POSITRON

Antielectron

POSITRON
First antiparticle discovered
POSITRON
Basic particle
POSITRONPhysics particle
POSITRONBeta decay emission, sometimes
POSITRONAntiparticle first observed in 1929