Difference Between Alpha Beta and Gamma Radiation

Alpha Beta vs Gamma Radiation

A stream of energy quanta or particles with high energy is known as radiation. It naturally occurs when an unstable nucleus transforms into a stable nucleus. The excess energy is carried away by these particles or quanta.

Alpha Radiation (α Radiation)

A helium-4 nucleus emitted by a larger atomic nucleus during radioactive decay is known as an alpha particle. During the decay, the parent nucleus loses two protons and two neutrons, which consists the alpha particle. Therefore, the nucleon number of the parent nucleus decrease by 4 and atomic number drops by 2 and no electrons are bound to the Helium nucleus. This process is known as the alpha decay, and the stream of alpha particles is known as alpha radiation.

Alpha particles are positively charged with the lowest energy and lowest speed compared to other radiations emitted from a nucleus. It quickly loses the kinetic energy and transform into a helium atom. It is also heavy and larger in size. In the process, it releases considerably large amount of energy in a small area. Therefore, alpha radiation is more harmful than the other two forms for radiation. In an electric field, alpha particles move parallel to the direction of the field. It has the lowest e/m ratio. In magnetic field, alpha particles take a curved trajectory with lowest curvature in a plane perpendicular to the magnetic field.

Beta Radiation (β Radiation)

An electron or positron (anti-particle of electron) emitted during the beta decay is known as a Beta particle. A stream of positrons or electrons (beta particles) emitted through beta decay is known as beta radiation. Beta decay is a result of weak interaction in the nuclei.

In beta decay, an unstable nucleus changes its atomic number keeping its nucleon number constant. There are three types beta decay.

Positive beta decay: A proton in the parent nucleus transforms into a neutron by emitting a positron and a neutrino. The atomic number of the nucleus decreases by 1.

Negative beta decay: A neutron transforms into a proton by emitting an electron and a neutrino. The atomic number of the parent nucleus increase by 1.


Electron Capture: a proton in the parent nucleus transforms into a neutron by capturing an electron from the environment. It emits neutrino during the process. The atomic number of the nucleus decreases by 1.

Only positive beta decay and negative beta decay contribute beta radiation.

Beta particles have intermediate energy levels and speeds. Penetration into material is also moderate. It has a much higher e/m ratio. When moving through a magnetic field, it follows a trajectory with much higher curvature than the alpha particles. They move in a plane perpendicular to the magnetic field, and the movement is in the opposite direction to the alpha particles for electrons and in the same direction for positrons.

Gamma Radiation (γ Radiation)

A stream of high energy electromagnetic quanta emitted by excited atomic nuclei is known as gamma radiation. Excess energy is released in the form of electromagnetic radiation when the nuclei are passing to a lower energy state. Gamma quanta have energy from about 10-15 to 10-10 Joule (10 keV to 10 MeV in electron volts).

Since the gamma radiation is electromagnetic waves and has no rest mass, e/m is infinite. It shows no deflection in either magnetic or electric fields. Gamma quanta have much higher energy than alpha and beta radiation particles.

What is the difference between Alpha Beta and Gamma Radiation?

• Alpha and beta radiation are stream of particles consisting mass. Alpha particles are He-4 nuclei, and beta is either electrons or positrons. Gamma radiation is an electromagnetic radiation and consists of high energy quanta.

• When alpha particle is released the nucleon number and the atomic number of the parent nucleus changes (transforms into another element). In beta decay, the nucleon number remains unchanged while the atomic number increases or decreases by 1 (again transforms into another element). When a gamma quanta is released, both nucleon number and atomic number remain unchanged, but the energy level of the nucleus decreases.

• Alpha particles are the heaviest particles, and beta particles have relatively very small mass. Gamma radiation particles have no rest mass.

• Alpha particles are positively charged while beta particles can have either positive or negative charge. A gamma quantum has no charge.

• Alpha and beta particles show deflection when moving through magnetic fields and electric fields. Alpha particles have a lower curvature when moving through electric or magnetic fields. Gamma radiation shows no deflection.

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