A manufacturer makes single-use plastic blood-collection bags. The plastic starts to deform above 70 ∘C70\ ^\circ\text{C}70 ∘C.
Each bag is placed in a paper-and-plastic packet, with the packet sealed at the stage shown in the table. Identical bags are covered with the same number of microorganisms before each sterilisation trial.
The table shows the results.
| Process | Treatment | Temperature of bag during treatment | Packet sealed | Living microorganism colonies immediately after treatment | Living microorganism colonies after seven days in the unopened packet |
|---|---|---|---|---|---|
| A | steam | 120 ∘C120\ ^\circ\text{C}120 ∘C | after treatment | 0 | 14 |
| B | alpha radiation | 20 ∘C20\ ^\circ\text{C}20 ∘C | before treatment | 118 | 121 |
| C | gamma radiation | 20 ∘C20\ ^\circ\text{C}20 ∘C | before treatment | 0 | 0 |
Explain which process the manufacturer should use.
Use the data and the properties of the radiation in your answer.
97 exam-style questions on Edexcel GCSE Physics 6.5 Uses and dangers of radioactivity, covering 6.5.1 Uses of radioactivity, 6.5.2 Dangers of ionising radiation and precautions, 6.5.3 Half-life and radiation dangers, 6.5.4 Safety precautions for radiation exposure, and 6.5.5 Contamination and irradiation. Each one has a worked solution and a mark scheme showing where the marks go.