On the CD-V700 Rad Meter, which detector is used to measure alpha, beta, and gamma (exposure)?

• A. Silver probe
• B. Pancake detector
• C. External detector
• D. Optical sensor

Answer: (B)

A single detector with broad response is used because this instrument is meant to be a general-purpose survey meter that can read exposure from multiple radiation types without swapping sensors. The pancake detector is a flat, large-area Geiger-Mueller tube with a very thin window, which gives it a good, wide-range sensitivity. That thin window allows alpha particles to reach the gas when the source is in contact, while the large surface area and the tube’s design also provide reliable detection of beta and gamma radiation. Because of this combination, the pancake detector can measure exposure from all three types with a practical, easy-to-use setup, which is exactly what the CD-V700 Rad Meter is designed to do. The other options are more specialized or not suited for measuring all three types in a single, handheld meter: the silver probe is typically for direct alpha measurements, an external detector implies a separate unit, and an optical sensor does not detect ionizing radiation.