A scintillation counter detects radioactivity by:
A) none of the answers.
B) emission of light from a NaI crystal when radioactivity passes through the crystal.
C) ionization of argon gas in a chamber which produces an electrical signal.
D) analyzing the mass and velocity of each particle.
E) developing film which is exposed by radioactive particles.
The correct answer for how a scintillation counter detects radioactivity is option B) emission of light from a NaI crystal when radioactivity passes through the crystal.
To understand how a scintillation counter works, we need to know that when certain types of radioactivity interact with certain materials, they produce flashes of light. In a scintillation counter, a common material used is a sodium iodide (NaI) crystal, which can emit light when excited by ionizing radiation.
Here are the steps involved in the detection process:
1. Radioactive particles or rays, such as alpha, beta, or gamma particles, pass through the NaI crystal.
2. As these radioactive particles interact with the atoms in the crystal, they transfer energy to the atoms, causing them to become excited.
3. Excited atoms in the NaI crystal quickly release the absorbed energy in the form of flashes of light. This phenomenon is known as scintillation.
4. The emitted light is detected by a sensitive component within the scintillation counter, such as a photomultiplier tube or a solid-state detector.
5. The detector converts the flashes of light into electrical signals, which can be measured and recorded.
By analyzing the intensity and timing of the scintillation flashes, the scintillation counter can determine the characteristics of the radioactive particles or rays, such as their energy levels and intensities. This information helps in quantifying and studying different aspects of radioactivity.
Therefore, in summary, a scintillation counter detects radioactivity by using a NaI crystal to produce flashes of light when radioactive particles or rays pass through it, and then converting the emitted light into electrical signals for analysis.