Beta rays (β-rays) are a type of radioactive radiation consisting of high-energy electrons (β⁻) or positrons (β⁺) emitted during beta decay. Beta radiation is lighter and faster than alpha radiation and has moderate penetration power, making it useful in medical and industrial applications.
Types of Beta Decay
There are two types of beta radiation, depending on whether the nucleus emits an electron or a positron:
| Type | Particle Emitted | Effect on Nucleus |
|---|---|---|
| Beta Minus (β⁻) Decay | Electron (e⁻) | A neutron changes into a proton, increasing atomic number by 1. |
| Beta Plus (β⁺) Decay (Positron Emission) | Positron (e⁺) | A proton changes into a neutron, decreasing atomic number by 1. |
How Beta Rays Are Produced
Beta rays are emitted when an unstable atomic nucleus undergoes beta decay to become more stable.
✔ Example of Beta Minus Decay:
Carbon-14 → Nitrogen-14 + Beta Particle (Electron) + Antineutrino
- A neutron inside the Carbon-14 nucleus turns into a proton, emitting an electron (beta particle) and an antineutrino.
✔ Example of Beta Plus Decay (Positron Emission):
Fluorine-18 → Oxygen-18 + Positron + Neutrino
- A proton inside Fluorine-18 turns into a neutron, emitting a positron (β⁺ particle) and a neutrino.
Properties of Beta Rays
✔ Negatively Charged (β⁻) or Positively Charged (β⁺) – Beta particles are either electrons (-1 charge) or positrons (+1 charge).
✔ Lighter and Faster than Alpha Particles – Travel at speeds up to near the speed of light.
✔ Moderate Penetration Power – Can pass through paper but are stopped by plastic, aluminum, or a few millimeters of metal.
✔ Ionizing Radiation – Can damage DNA and cells, making them useful for medical treatment but hazardous in high doses.
Sources of Beta Radiation
✔ Radioactive Elements: Found in isotopes like Carbon-14, Strontium-90, and Phosphorus-32.
✔ Nuclear Reactions: Beta particles are emitted during fission reactions in nuclear reactors.
✔ Cosmic Rays: High-energy beta radiation is present in cosmic radiation from space.
Uses of Beta Rays
1. Medicine (Cancer Treatment & Diagnosis)
✔ Radiotherapy for Cancer: Strontium-90 and Yttrium-90 beta emitters target and destroy cancer cells.
✔ PET Scans (Positron Emission Tomography): Fluorine-18 emits positrons (β⁺), allowing detailed imaging of the brain and tumors.
2. Industrial Applications
✔ Thickness Control: Beta rays are used to measure the thickness of paper, plastic, and metal sheets in manufacturing.
✔ Tracer Studies: Radioactive beta-emitting isotopes track fluid movement in pipelines and soil analysis.
3. Scientific Research & Carbon Dating
✔ Carbon-14 Dating: Beta decay of Carbon-14 helps determine the age of fossils and ancient artifacts.
✔ Biological & Chemical Tracing: Phosphorus-32 is used in DNA and cellular studies.
Dangers and Safety Measures of Beta Radiation
⚠ Penetrates Skin but Less than Gamma Rays – Can cause radiation burns and DNA damage.
⚠ Inhalation/Ingestion Risk – Beta emitters like Strontium-90 can accumulate in bones and pose long-term health risks.
⚠ Causes Ionization Damage – Prolonged exposure increases cancer risk.
🔹 Safety Measures:
✔ Plastic, Glass, or Aluminum Shielding – Beta rays can be blocked by a few millimeters of metal or acrylic.
✔ Protective Clothing & Gloves – Prevents direct contact with radioactive sources.
✔ Radiation Monitoring – Workers handling beta emitters wear dosimeters to track exposure levels.
Comparison: Beta Rays vs. Alpha & Gamma Rays
| Property | Alpha Rays (α) | Beta Rays (β) | Gamma Rays (γ) |
|---|---|---|---|
| Charge | +2 (Helium nucleus) | -1 or +1 (Electron or Positron) | 0 (Neutral) |
| Mass | Heavy | Light | Massless (Pure Energy) |
| Speed | Slow (~5% speed of light) | Fast (~99% speed of light) | Speed of light |
| Penetration Power | Low (Blocked by paper, skin) | Moderate (Blocked by plastic, aluminum) | High (Needs lead or thick concrete) |
| Ionization Power | Very High | Medium | Low |
Conclusion
Beta rays are moderate-penetration radiation consisting of electrons (β⁻) or positrons (β⁺). They are widely used in medical treatments, industrial processes, and carbon dating, but require careful handling to minimize radiation exposure risks.