An environmental scientist investigates the ionizing radiation emitted by three soil samples, labelled X, Y, and Z, collected near an industrial site. She does this by measuring the amount of radiation (the count) received by a detector.
She uses the following method:
The scientist then measures the count for each sample again, using paper, aluminium, and lead as absorbing materials between the sample and the detector.
Name two pieces of equipment that the scientist would need to use in order to measure the count rate in this investigation.
Table 1 shows the results of the scientist's investigation.
Table 1
| Count with no absorber | Count with paper | Count with aluminium | Count with lead | |
|---|---|---|---|---|
| Sample X | 2500 | 2480 | 600 | 18 |
| Sample Y | 1800 | 19 | 18 | 17 |
| Sample Z | 8000 | 3200 | 21 | 19 |
Copy and complete the table below by ticking (✓\checkmark✓) the boxes to show which types of radiation are emitted by each sample.
| Alpha | Beta | Gamma | |
|---|---|---|---|
| Sample X | |||
| Sample Y | |||
| Sample Z |
Suggest why there is still a count recorded for each sample, even when lead is used as an absorbing material.
Another radioactive source, W, has a half-life of 6 days6\text{ days}6 days.
State what is meant by the term half-life.
The initial count rate for source W is 1600 counts per minute1600\text{ counts per minute}1600 counts per minute. Estimate how many days it will take for the count rate for source W to fall below 250 counts per minute250\text{ counts per minute}250 counts per minute.
