History and Uses of Accelerators - doe-hdbk-1108-2002

DOE-HDBK-1108-2002

Radiological Training for Accelerator Facilities

Instructor's Guide

Lesson Plan

Notes

HISTORY AND USES OF ACCELERATORS

Definition

Accelerators are devices employing electrostatic or

electromagnetic fields to input kinetic energy to molecules,

atomic or subatomic particles. This training is provided

because accelerators also are capable of creating a radiological

area and other radiological hazards.

Need for Accelerators

In the early 1900s, radioactive particles could be obtained only from

materials found in nature. The studies that physicists wanted to

perform required both higher intensities and higher energies than were

obtainable from the natural sources. The ability to vary energy and

intensity to suit a particular experiment was also desirable.

In the 1930s, scientists began to build machines that produced

the needed degree of control. These machines were called

accelerators.

The Development of the Accelerator

The earliest accelerators were simple vacuum tubes in which

electrons were given an increase in energy by the voltage

difference between two oppositely charged electrodes.

Acceleration

The acceleration of the electron by this electrical force also

increases the energy of the electron.

Electron volt

The amount of acceleration is determined by the potential

difference measured in volts (V) in this electrical field.

One electron volt (eV) is the energy gained by an electron

accelerated through a potential difference of one volt.

An electron accelerated across a gap by means of a

10,000 volt, or 10 kilovolt (kV), potential difference is

said to have gained 10,000 electron volts (10 keV) of

energy after crossing the gap.