Question: How does the dosimeter work ?

Clara Nellist answered on 13 Mar 2014:

The main job of a dosimeter is to check how much radiation I personally get from my work. When I’m doing an experiment with a beam of particles, there will be some radiation given off. But there are always small amounts radiation around, so we want to know how much extra I’m getting and if I should be worried.

The type of dosimeter that I have to wear around my neck is for measuring how much radiation I get over a long period of time (e.g. months or years). There are two parts, one called a Fast Neutron dosimeter which measures neutrons (neutral particles from an atom) because they are a good indication of how much radiation I’ve been around. There is also a gamma detector which measures gamma particles (these are really energetic photons, like light particles, that we can’t see). Both of these parts are known as passive dosimeters, meaning that they won’t alert me if there’s suddenly a lot of radiation. We only know how much I’ve had once I plug it into a machine. Then the numbers it has recorded are sent to a person at a computer who keeps track of everyone’s radiation amount. I have to plug my dosimeter into the machine at least once a month, but ideally more often if possible.

There are also other dosimeters in the experimental area, and these are active dosimeters. They will test if there is suddenly a lot of radiation at once, and if there is an alarm will go off and I should leave right away! But this has never happened to me.