A student carries out an experiment to investigate the shielding of different types of radiation. The detector is placed at a fixed distance of 8 cm from the source, and count rates are recorded for 60 s using different absorbing materials.
The table below shows the student's results:
| Source used | Count in 60 s with no absorber | Count in 60 s with 0.1 mm of paper | Count in 60 s with 5 mm of aluminium | Count in 60 s with 5 mm of lead |
|---|---|---|---|---|
| Source X | 8500 | 8490 | 8100 | 4200 |
| Source Y | 12000 | 11800 | 32 | 30 |
| None | 30 | 29 | 31 | 30 |
Explain why there is a reading recorded when no source is used.
State why the student must keep the distance between the source and the detector constant throughout the experiment.
Using the data from the table, identify and explain the type of radiation emitted by: (i) Source Y
Source X