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An accelerator in physics is a device designed to bring charged particles, such as protons and electrons, to high speeds and energies. These accelerated particles have various applications in industry, medicine, and pure physics. Accelerators play a crucial role in generating X-rays, producing television images, medical treatments (e.g., destroying tumor cells), and exploring the fundamental forces through high-energy particle collisions.
Key points about accelerators:
- Early Accelerators: The first accelerators used high voltages, often generated by Van de Graaff generators, to produce a strong electric field through which charged particles were accelerated. However, these accelerators had limitations due to the voltage constraints.
- Linear Accelerator (Linac): The linear accelerator, or linac, was an innovation that replaced the high-voltage accelerators. In a linac, particles pass through a series of metal tubes (drift tubes) with alternating electric fields, receiving successive pushes to accelerate them.
- Cyclotron: Another approach involves bending the path of particles into a circular trajectory, allowing them to pass repeatedly through the same electric field. The cyclotron, pioneered by Ernest Lawrence in the 1930s, is an example of such an accelerator.
- Tevatron and Large Hadron Collider (LHC): The Tevatron at Fermilab and the Large Hadron Collider (LHC) at CERN are examples of powerful accelerators that collide particles at extremely high energies. The LHC, with a 27 km circumference, explores the fundamental particles and forces at play in the universe.
- Stanford Linear Collider: The Stanford Linear Collider is a colliding beam machine where electrons and positrons are accelerated along a straight track and then steered to a head-on collision with other particles, such as protons and neutrons.
- Elementary Particles: Accelerators have been instrumental in experiments revealing the substructure of protons and neutrons, indicating the existence of smaller elementary particles called quarks.
Accelerators are indispensable tools in the field of particle physics, providing insights into the fundamental building blocks of matter and the forces governing the universe. They continue to contribute to scientific discoveries and technological advancements.
The cyclotron, an early accelerator, consisted of two D-shaped hollow chambers enclosed in a vacuum.
An alternating voltage was applied across the gap between the hollows. Charged particles spiralled outward
from the centre, picking up energy and accelerating each time they passed through the gap.