Neutrons - hdbk-1130-98

DOE-HDBK-1130-98

Module 1: Radiological Fundamentals

Instructor's Notes

4. Neutrons

a. Physical characteristics

1) Neutron radiation consists of neutrons that are ejected from the

nucleus.

2) A neutron has mass, but no electrical charge.

EO6 Identify the four basic

types of ionizing radiation

and the following for each

type:

a. Physical characteristics

b. Range

c. Shielding

d. Biological hazards

e. Sources

3) An interaction can occur as the result of a collision between a

neutron and a nucleus. The nucleus recoils due to the energy

imparted by the neutron and ionizes other atoms. This is

called "secondary ionization."

4) Neutrons may also be absorbed by a nucleus. This is called

neutron activation. A charged particle or gamma ray may be

emitted as a result of this interaction. The emitted radiation

can cause ionization in other atoms.

b. Range

1) Because of the lack of a charge, neutrons have a relatively high

penetrating ability and are difficult to stop.

2) The range in air is very far. Like gamma rays, they can easily

travel several hundred feet in air.

c. Shielding

Neutron radiation is best shielded by materials with a high

hydrogen content such as water, concrete, or plastic.

d. Biological hazards

Neutrons are a whole body hazard due to their high penetrating

ability.