Final answer:
The purpose of the control dosimeter is to measure the ambient dose rates in radioactive material storage areas.
Step-by-step explanation:
The purpose of the control dosimeter is to measure the ambient dose rates in areas where radioactive materials are stored. It is important to monitor radiation levels in storage areas to ensure the safety of individuals working in those areas. By measuring the dose rates, we can identify any potential risks and take appropriate precautions to minimize exposure to radiation.