IONISING RADIATION PUT TO USE18.1

Modelling radioactive decay18.1 Ionising radiation put to use

Modelling radioactive decay using dice

We can use dice to model the decay of dice. Roll your dice and record the number of dice that have rolled a 6. Record this value in the table. Roll the remaining dice. Repeat.

Roll Dice remaining

0

1

2

3

4

5

6

7

8

9

10

Now plot the data, adding a line of best fit following the plotted data. It should be an exponential decay plot.

Roll

Dic

e re

mai

ning

What is the half-life of this sample of dice?

Show your calculation on the graph

Learning objectives• Ionising radiations have a wide range of uses, in medicine, technology

and everyday life• Ionising radiations mainly interact with matter by ionising atoms. Alpha

radiation is strongly ionising, beta and gamma less so• Alpha particles have a definite range in air. Beta particles have a

variable range. Gamma radiation is attenuated exponentially in absorbing material with I = I0e-µx

• The unit of absorbed dose is the gray Gy, the energy in joule absorbed per kilogram of material. The unit of dose equivelant is the sievert Sv, the absorbed dose is gray multiplied by numerical factors to allow for the different effects of different types of radiation and tissue

• The concept of risk combines the probability of an event with the consequences of that event occuring: risk = probability x consequence

IONISING RADIATIONS HAVE A WIDE RANGE OF USES, IN MEDICINE, TECHNOLOGY AND EVERYDAY LIFE

18.1 Ionising radiation put to use

Med

ical

radi

ogra

phy

Nuclear power

Non destructive testing

Smoke detectors

Radioactive tracers

Sterile insect technique

IONISING RADIATIONS MAINLY INTERACT WITH MATTER BY IONISING ATOMS. ALPHA RADIATION IS STRONGLY IONISING, BETA AND GAMMA LESS SO

18.1 Ionising radiation put to use

ALPHA PARTICLES HAVE A DEFINITE RANGE IN AIR. BETA PARTICLES HAVE A VARIABLE RANGE. GAMMA RADIATION IS ATTENUATED EXPONENTIALLY IN ABSORBING MATERIAL WITH I = I0E-ΜX

18.1 Ionising radiation put to use

THE UNIT OF ABSORBED DOSE IS THE GRAY GY, THE ENERGY IN JOULE ABSORBED PER KILOGRAM OF MATERIAL. THE UNIT OF DOSE EQUIVELANT IS THE SIEVERT SV, THE ABSORBED DOSE IS GRAY MULTIPLIED BY NUMERICAL FACTORS TO ALLOW FOR THE DIFFERENT EFFECTS OF DIFFERENT TYPES OF RADIATION AND TISSUE

18.1 Ionising radiation put to use

THE CONCEPT OF RISK COMBINES THE PROBABILITY OF AN EVENT WITH THE CONSEQUENCES OF THAT EVENT OCCURING: RISK = PROBABILITY X CONSEQUENCE

18.1 Ionising radiation put to use