a low-energy electron emitted by a substance after bombardment by higher-energy particles, as alpha particles.
Origin of delta ray
First recorded in 1905–10
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
a particle, esp an electron, ejected from matter by ionizing radiation
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012