**Antiparticle of Electron: Positron**

The antiparticle of an electron is called a positron. The concept of antiparticles arises from the theory of quantum mechanics and is an important aspect of particle physics.

**Definition of Antiparticle:**

An antiparticle is the particle that has the same mass as another particle but with opposite electric charge, quantum spin, and other quantum numbers. Antiparticles are denoted by a bar or a prime symbol over the particle's symbol. For example, the antiparticle of an electron is denoted as e⁺ (pronounced as "e-plus").

**Positron as the Antiparticle of Electron:**

The positron is the antiparticle of the electron. It was first predicted by Paul Dirac in 1928, and its existence was later confirmed experimentally. The positron is identical to the electron in mass but has a positive charge (+1e) instead of a negative charge (-1e).

**Characteristics of Positrons:**

1. Charge: The positron carries a positive charge, which is opposite to the negative charge of the electron.

2. Quantum Spin: The positron has a spin of 1/2, just like the electron.

3. Mass: The positron has the same mass as the electron, approximately 9.10938356 × 10⁻³¹ kilograms.

4. Annihilation: When a positron encounters an electron, they can annihilate each other, resulting in the production of high-energy gamma rays. This process is called electron-positron annihilation.

**Applications of Positrons:**

Positrons have several applications in various fields:

1. Medical Imaging: Positron Emission Tomography (PET) scans use positron-emitting isotopes to study the functioning of organs and tissues in the human body.

2. Particle Physics Research: Positrons are used in high-energy particle accelerators to study fundamental interactions and the behavior of subatomic particles.

3. Material Science: Positron annihilation spectroscopy is a technique used to study the defects and properties of materials.

In conclusion, the antiparticle of an electron is the positron. The positron has the same mass as the electron but carries a positive charge. It plays a crucial role in various fields such as medical imaging, particle physics research, and material science.