Chemistry · Chapter 21

Shielding, Dose and Medical Isotopes

Put paper, metal or lead in front of alpha, beta and gamma rays and see what gets through. Then weigh real doses against each other and find out why each isotope has the job it has.

The shielding bench source on the left, detector on the right

Radiation from a source meeting a slab of shielding
Kind of radiation
Shielding material

Real doses, on a scale that fits them all

Real radiation doses compared on a ten-fold scale

Each step across is ten times the dose, which is the only way these numbers fit on one page.

What got through

0.0percent through fully stopped
Counts at the detector: 0 of 1,000
How this material acts: absorbs it completely
Half-value layer: not applicable
Quality factor for this kind: 20

Grays into sieverts

40.0mSv dose equivalent

Add up your own year

Natural background where most people live: 3.1 mSv



3.5mSv this year ordinary

Isotopes with a job

What this bench is telling you

Reading the bench
Paper stops alpha radiation
An alpha particle carries two units of charge and four units of mass, so it loses its energy almost at once.