Recommended for High School.
Alpha, beta, gamma, and X-rays can pass through matter, but can also be absorbed or scattered in varying degrees, depending on the material and on the type and energy of the radiation. Medical X-ray images are possible because bones absorb X-rays more than soft tissues. Strongly radioactive sources are often stored in lead boxes to shield the local environment from the radiation.
Some materials absorb beta rays. A sheet of common cardboard will absorb some of the betas, but will allow most to pass through. You can measure this absorption by fixing a beta source and a radiation monitor so their positions do not change, and then inserting layers of cardboard between them.
When an absorber is in the path of beta rays, it will allow a certain fraction, ƒ, to pass through. The fraction depends on the density and thickness of the absorber, but will be a constant for identical absorbers and fixed beta-ray energy. If the number of counts detected in a count interval is N0 when no absorber is in place, then the counts, N, with the absorber, will be N = ƒ N0. In the preliminary questions, you will develop a more general expression for additional layers of cardboard absorbers, and then test it against real data.
You will use a small source of beta radiation for this experiment. Beta rays are high-energy electrons. Follow all local procedures for handling radioactive materials.
In this experiment, you will
- Develop a model for the absorption of beta radiation by matter.
- Use a radiation counter to study how the radiation emitted by a beta source is absorbed by cardboard.
- Test the model against experimental data to determine its validity.
Sensors and Equipment
This experiment features the following Vernier sensors and equipment.
You may also need an interface and software for data collection. What do I need for data collection?
See all standards correlations for Advanced Chemistry with Vernier »