Which detector uses an electric field to collect charge from X-ray, gamma, and particle interactions?

Which detector uses an electric field to collect charge from X-ray, gamma, and particle interactions?

• A. Scintillation detectors
• B. Semiconductor detectors
• C. Geiger-Muller counters
• D. Ionization chambers

Answer: (B)

Electric field-driven charge collection in a solid-state medium is the hallmark of semiconductor detectors. When X-rays, gamma rays, or charged particles deposit energy in a silicon (or other semiconductor) detector, they create many electron-hole pairs. An applied electric field across the detector (usually across a biased p–n junction or diode) quickly drifts those charge carriers toward the electrodes. The collected charge produces a current pulse whose size is proportional to the energy deposited, giving both detection and energy information with good resolution. Other detectors operate differently. Scintillation detectors convert the radiation energy into light, and that light is then measured by a photodetector, so the signal comes from light rather than directly from charge in the solid; this adds an extra conversion step and typically worse energy resolution. Geiger–Müller counters use a strong electric field to cause avalanche multiplication, yielding a standardized pulse rather than an energy-proportional signal. Ionization chambers also collect charges in a gas, but their signals are generally not as suitable for precise energy measurements as solid-state devices. So the defining feature here is collecting the radiation-induced charge directly in a solid-state material via an electric field, which is characteristic of semiconductor detectors.

Electric field-driven charge collection in a solid-state medium is the hallmark of semiconductor detectors. When X-rays, gamma rays, or charged particles deposit energy in a silicon (or other semiconductor) detector, they create many electron-hole pairs. An applied electric field across the detector (usually across a biased p–n junction or diode) quickly drifts those charge carriers toward the electrodes. The collected charge produces a current pulse whose size is proportional to the energy deposited, giving both detection and energy information with good resolution.

Other detectors operate differently. Scintillation detectors convert the radiation energy into light, and that light is then measured by a photodetector, so the signal comes from light rather than directly from charge in the solid; this adds an extra conversion step and typically worse energy resolution. Geiger–Müller counters use a strong electric field to cause avalanche multiplication, yielding a standardized pulse rather than an energy-proportional signal. Ionization chambers also collect charges in a gas, but their signals are generally not as suitable for precise energy measurements as solid-state devices.

So the defining feature here is collecting the radiation-induced charge directly in a solid-state material via an electric field, which is characteristic of semiconductor detectors.