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British Science Week


The Cloud Chamber experiment | a journey into the world of particle physics

During British Science Week our Year 1 Physics students were given an opportunity to observe tracks made by high energy particles using a cloud chamber which they constructed using very basic materials and equipment. 

Year 1 student, Sinni Chandra writes - the cloud chamber experiment is a scientific tool that allows us to observe the behaviour of subatomic particles that are naturally invisible to the human eye. This experiment is usually conducted to test the presence of radiation in our environment which is known as background radiation.

What is the cloud chamber?

A Cloud Chamber is a sealed container filled with a gas such as alcohol which is cooled by dry ice filled at the bottom of the container.  As the high-energy particles pass through the gas, they ionise the molecules which creates a trail of charged particles. This process causes the gas to condense into small droplets which creates a visible trail of vapour that can be seen by the naked eye.

How has the experiment been conducted?

To conduct this experiment, we used a large transparent container with a lid, isopropyl alcohol, and dry ice. The container is filled with a small amount of alcohol, which is then supercooled by placing dry ice on top of the container. This container must be placed in a dark room with a bright light shining into the container from the side, this helps observe the subatomic particles. The particles paths are seen as thin, white trails that look a bit like tadpoles.

Sinni Chandra - Year 1 Physics Student


Alpha particles being emitted from a rod made of tungsten