---
tags:
  - science/physics
  - electromagnetic-radiation
  - x-ray
  - gamma-ray
  - ionizing-radiation
  - sensors
created: 2026-05-16
breadcrumb: "Physics > Electromagnetic radiation > X-ray & gamma ray"
---

# X-ray & gamma ray

> **Mechanism:** Ionizing photon interaction

## Items

- **Scintillator + PMT** — High-Z crystal (NaI, BGO, LYSO) converts γ to visible photons; a PMT reads. Backbone of nuclear medicine and security imaging.
- **HPGe detector** — High-purity germanium; the gold standard for γ-ray spectroscopy. Liquid-nitrogen cooled.
- **CdTe / CZT** — Room-temperature γ semiconductor. Compact imaging without cryogenics.
- **Geiger–Müller tube** — Gas-filled tube; ionising photon triggers an avalanche that is counted. No energy info.
- **Image intensifier** — Photocathode → MCP → phosphor. Converts low-light, UV, or X-ray into a viewable image.

## Related

- [[ultraviolet]]