Nuclear Radiation: Detection and Measurement

Nuclear radiation — alpha (α), beta (β), and gamma (γ) — is invisible, odourless, and cannot be felt. Yet it interacts with matter in predictable ways, and these interactions form the basis of all detection methods. This lesson covers the key detectors you need to know for Edexcel A-Level Physics, along with the important concepts of background radiation, count rate, and the inverse square law for gamma radiation.

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Types of Nuclear Radiation — A Brief Review

Property	Alpha (α)	Beta (β⁻)	Gamma (γ)
Nature	⁴He nucleus (2p + 2n)	High-speed electron	Electromagnetic wave
Charge	+2e	−e	0
Mass	~4 u	~1/1836 u	0
Speed	~5% of c	Up to ~99% of c	c
Range in air	~5 cm	~1 m	Inverse square law — no definite range
Stopped by	Paper / skin	~3 mm aluminium	Several cm of lead / thick concrete
Ionising ability	Very high	Moderate	Low

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Geiger-Müller Tube and Counter