Two researchers separately examine mineral samples that contain unstable nuclei. Both researchers wear outer gloves.
When the work is finished, both samples are returned to a shielded store. A detector is held 2 cm from each researcher's gloved hand. The background count rate is 18 counts per minute.
| Measurement | Count rate in counts per minute |
|---|---|
| Researcher A beside the mineral sample | 620 |
| Researcher A in a clean room after the sample is stored | 20 |
| Researcher B beside the mineral sample | 430 |
| Researcher B in a clean room after the sample is stored | 410 |
| Researcher B after the outer gloves are removed and taken out of the room | 19 |
Explain what the count rates show about how Researcher A and Researcher B were exposed, and why Researcher B's exposure would continue if the outer gloves were not removed.