Neutrons - doe-hdbk-1108-2002

DOE-HDBK-1108-2002

Radiological Training for Accelerator Facilities

Student's Guide

Lesson Plan

Notes

Neutrons

Neutrons can be produced through nuclear interactions of the

primary or secondary beam with matter. They can also be

produced by interaction of high-energy photons about with

matter (photoneutron reaction). The photoneutron reaction

typically requires photons with energy in excess of 10 MeV.

Neutron radiation is a concern within any area where

the beam can interact with physical objects.

Location of potential sources of neutron radiation

exposure. (Facility-Specific).

Muons

Muons are particles that are physically similar to electrons, but

about 200 times heavier. Like electrons, they can be positively

or negatively charged

Muons are produced by several mechanisms and

require photon energies greater than 212 MeV or

proton energies greater than 140 MeV.

Muons are not usually seen in significant amounts at

machines with energies less than 1 giga electron-volt

(GeV).

Muons travel mainly in the direction of the beam that

produced them with very little deviation from the

beam path. They are a concern directly downstream of

targets, beam dumps, etc. Muons are ionizing particles

and can deliver a very high dose.

Muons lose energy only through ionization and are

very penetrating. Large amounts of earth or steel are

typically used to shield muons.