A beta ray is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus.

Here's a breakdown of its composition:

* Beta Minus (β-) Decay: In this type of decay, a neutron within the nucleus transforms into a proton, emitting an electron (β-) and an antineutrino.

* Beta Plus (β+) Decay: In this type of decay, a proton within the nucleus transforms into a neutron, emitting a positron (β+) and a neutrino.

Key Points:

* Electrons: Beta rays are essentially fast-moving electrons.

* Positrons: In some cases, beta rays are positrons, which are the antimatter counterpart of electrons (same mass but opposite charge).

* Antiparticles: The emission of positrons involves the creation of an antiparticle.

* High Energy: Beta rays are energetic particles, capable of ionizing atoms and causing damage to living tissues.

Let me know if you'd like more details about the processes of beta minus and beta plus decay!