CBSE NOTES CLASS 12 PHYSICS
CHAPTER 13 NUCLEUS
β-rays consist of fast moving electrons.
When a β-particle is emitted by a nucleus its atomic number is increases by 1 and mass number remains unchanged.
The emission of electron in β− decay is accompanied by the emission of an antineutrino (); in β+ (positron) decay a neutrino (ν) is generated. Neutrinos are neutral particles with very small (possiblly, even zero) mass compared to electrons. They have only weak interaction with other particles. They are, therefore, very difficult to detect, since they can penetrate large quantity of matter (even earth) without any interaction.