## Cyclotron – Class 12 | Chapter – 4 | Physics Short Notes Series PDF for NEET & JEE

Cyclotron: A cyclotron is a type of particle accelerator that uses a combination of electric and magnetic fields to increase the energy of charged particles. The charged particles are accelerated in a spiral path between the poles of two D-shaped electrodes, and the energy of the particles is increased with each orbit through the magnetic field.

The basic principle of the cyclotron is that a charged particle moving in a magnetic field experiences a centripetal force that is proportional to its velocity. By applying an alternating electric field between the electrodes, it is possible to accelerate the charged particles and increase their velocity with each orbit. The magnetic field ensures that the charged particles remain in a spiral path, and it increases the energy of the particles by increasing their velocity.

The cyclotron was first developed in the 1930s and has since been used in a wide range of applications, including nuclear physics, medical physics, and material science. The cyclotron is especially useful for producing high-energy beams of light ions, such as protons and deuterons, and it is commonly used in medical applications for producing beams of charged particles for cancer therapy.

## Working Principle of Cyclotron

The working principle of a cyclotron can be understood in terms of the interaction between charged particles and electric and magnetic fields. Here’s a step-by-step explanation of how a cyclotron works:

• Generation of charged particles: The first step in the operation of a cyclotron is the generation of charged particles. This can be done through various methods, such as ionization of a gas, injection of ions from a source, or extraction of ions from a plasma.
• Acceleration in electric field: The charged particles are then accelerated in an electric field between two D-shaped electrodes, known as dees. The electric field is created by applying a high-frequency voltage to the dees. The charged particles experience a force proportional to their charge and the electric field, which causes them to accelerate towards the opposite dee.
• Movement in magnetic field: As the charged particles move towards the opposite dee, they enter a uniform magnetic field that is perpendicular to their velocity. The magnetic field causes the charged particles to experience a force proportional to their velocity and the magnetic field. This force is perpendicular to both the velocity of the particles and the direction of the magnetic field, and it causes the charged particles to move in a spiral path.
• Increasing energy with each orbit: With each orbit, the charged particles experience an alternating electric field between the dees, which increases their velocity and their energy. The magnetic field ensures that the charged particles remain in a spiral path, and it increases the energy of the particles by increasing their velocity. The charged particles continue to spiral through the magnetic field and gain energy with each orbit until they reach a maximum energy, at which point they are extracted from the cyclotron for use in experiments or applications.

## Uses of Cyclotron

Cyclotrons are versatile particle accelerators with a wide range of applications, including:

• Medical physics: Cyclotrons are widely used in medical physics for the production of radioisotopes for cancer therapy and diagnostic imaging. The high-energy beams produced by the cyclotron can be used to produce radioisotopes, which can then be used for cancer therapy or for imaging procedures, such as PET scans.
• Nuclear physics: Cyclotrons are used in nuclear physics for studying the properties of atomic nuclei and for producing high-energy beams of particles for use in various experiments. The beams produced by cyclotrons can be used to study the structure of nuclei, to determine the properties of short-lived isotopes, and to search for evidence of new forms of matter.
• Material science: Cyclotrons are used in material science for studying the properties of materials at the atomic and molecular level. The high-energy beams produced by the cyclotron can be used for spectroscopy, for imaging, and for other types of materials analysis.
• Environmental science: Cyclotrons can be used in environmental science for studying the isotopic composition of environmental samples, such as soil, water, and air. The isotopic composition of a sample provides information about the chemical and biological processes that have occurred in the environment.
• Basic research: Cyclotrons play a crucial role in basic scientific research by providing high-energy beams of particles for use in various experiments. The beams produced by the cyclotron can be used to study the properties of subatomic particles, to search for new forms of matter, and to explore the fundamental laws of physics.

## Limitations of Cyclotron

There are several limitations of cyclotrons, including:

• Size and cost: Cyclotrons are large and expensive devices, and they require a significant investment to construct and maintain. The size of the cyclotron is determined by the maximum energy of the particles that it produces, and the cost of the cyclotron is determined by the complexity of the accelerator and the cost of the components used in its construction.
• Complexity: Cyclotrons are complex devices that require a significant amount of technical expertise to construct and operate. The construction of a cyclotron requires a high degree of precision, and the operation of a cyclotron requires a detailed understanding of the interaction between charged particles and electric and magnetic fields.
• Limited energy range: Cyclotrons are limited in the range of particle energies that they can produce. The maximum energy of the particles produced by a cyclotron is determined by the size of the cyclotron, the strength of the magnetic field, and the frequency of the alternating voltage applied to the dees.
• Limited particle production rate: Cyclotrons are limited in the rate at which they can produce particles. The production rate of particles is determined by the number of particles that can be injected into the cyclotron, the efficiency of the acceleration process, and the rate at which the particles can be extracted from the cyclotron.
• Maintenance: Cyclotrons are complex and expensive devices that require a significant amount of maintenance to keep them operating efficiently. The maintenance of a cyclotron requires a high degree of technical expertise, and it can be time-consuming and expensive.

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