Cyclotron particle

Cyclotrons accelerate charged particles in a spiral path for nuclear and medical research, with radius increasing due to magnetic field.

About this subject

The cyclotron is a particle accelerator invented by Ernest Lawrence in 1932, which uses a constant magnetic field and a high-frequency alternating electric field to accelerate ions in a spiral path. Particles gain energy with each pass between two "D-shaped" hollow electrodes, reaching speeds near the speed of light. This principle enabled advances in nuclear physics, such as the discovery of isotopes and transuranium elements.

Today, cyclotrons are widely used in the production of radioisotopes for nuclear medicine, especially for PET (Positron Emission Tomography) diagnostics. Fluorine-18, for example, is produced in a cyclotron and used in cancer exams. Typical medical cyclotron energies range from 10 to 25 MeV, sufficient to generate these radiopharmaceuticals.

A fundamental limitation of the classic cyclotron is the relativistic effect: as the particle approaches the speed of light, its mass increases, causing desynchronization with the electric field. For higher energies, the synchrocyclotron and isochronous cyclotron were developed, which modulate the frequency or magnetic field to maintain synchrony.

In Brazil, the first cyclotron was installed at the University of São Paulo in 1954, boosting nuclear research. Today, the Institute for Energy and Nuclear Research (IPEN) operates a cyclotron to produce radioisotopes, supplying hospitals across the country.

Frequently Asked Questions

What is the difference between a cyclotron and a linear accelerator?

In a cyclotron, particles follow a spiral path in a constant magnetic field, reusing the same electrodes for successive accelerations. In a linear accelerator (linac), particles travel in a straight line through sequential accelerating cavities, without a magnetic field to bend the path.

How are cyclotrons used in medicine?

They produce short-lived radioisotopes such as fluorine-18 and carbon-11, used in PET (Positron Emission Tomography) scans. These radiopharmaceuticals help diagnose cancer, heart disease, and neurological disorders.

Why can't cyclotrons accelerate electrons?

Electrons are very light and experience strong relativistic effects even at low energies, quickly losing synchrony. To accelerate electrons, linear accelerators or synchrotrons are used.