15/09/2025
# 📘 A/L Physics – Particle Physics (துணிக்கை பௌதிகவியல்)
# # # 1. Introduction to Particle Physics
* **Particle Physics** → branch of physics dealing with **fundamental particles** and their interactions.
* Studies matter at **subatomic level**.
* Goal: to identify **elementary particles** and understand the **fundamental forces**.
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# # # 2. Classification of Particles
# # # # (A) **Hadrons** (ஹாட்ரான்கள்)
* Particles that interact through **strong nuclear force**.
* Made of **quarks**.
* Two types:
* **Baryons** (பேரியன்கள்) → composed of 3 quarks. e.g., **Proton (uud)**, **Neutron (udd)**.
* **Mesons** (மேசான்கள்) → composed of quark + antiquark. e.g., **π (pi meson)**, **K (kaon)**.
# # # # (B) **Leptons** (லெப்டான்கள்)
* Do **not** feel the strong force.
* Fundamental particles.
* Examples:
* **Electron (e⁻)**
* **Muon (μ⁻)**
* **Tau (τ⁻)**
* Their neutrinos: **νₑ, ν\_μ, ν\_τ**.
# # # # (C) **Bosons** (Force Carriers)
* Mediate the **fundamental interactions**.
* Examples:
* **Photon (γ)** → electromagnetic force.
* **Gluon (g)** → strong force.
* **W⁺, W⁻, Z⁰ bosons** → weak force.
* **Graviton (hypothetical)** → gravitational force.
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# # # 3. Fundamental Forces (அடிப்படை விசைகள்)
1. **Strong Nuclear Force** (வலுவான அணுக்கரு விசை) – mediated by **gluons**.
2. **Electromagnetic Force** (மின்காந்த விசை) – mediated by **photons**.
3. **Weak Nuclear Force** (பலவீன அணுக்கரு விசை) – mediated by **W, Z bosons**.
4. **Gravitational Force** (இருப்பு விசை) – mediated by **gravitons (theoretical)**.
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# # # 4. Quarks (குவார்க்குகள்)
* Six types (flavors):
1. **Up (u)**
2. **Down (d)**
3. **Strange (s)**
4. **Charm (c)**
5. **Top (t)**
6. **Bottom (b)**
* Properties:
* **Fractional charges**: +2/3 (up-type), –1/3 (down-type).
* Combine to form **hadrons**.
* Cannot exist independently (Quark Confinement).
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# # # 5. Antiparticles (எதிர் துணிக்கைகள்)
* Every particle has a corresponding **antiparticle** with:
* Same **mass**.
* Opposite **charge** (if charged).
* Examples:
* **Positron (e⁺)** = antiparticle of electron.
* **Antiproton (p̅)**.
* **Antineutrinos**.
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# # # 6. Conservation Laws in Particle Physics
1. **Conservation of Energy & Momentum**.
2. **Conservation of Charge**.
3. **Conservation of Baryon Number (B)**.
4. **Conservation of Lepton Number (L)**.
5. **Conservation of Strangeness (S)** (in strong & electromagnetic interactions, not always in weak).
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# # # 7. Standard Model of Particle Physics
* Organizes all known **elementary particles**:
* **Quarks** (u, d, c, s, t, b).
* **Leptons** (e⁻, μ⁻, τ⁻ and neutrinos).
* **Gauge Bosons** (γ, g, W, Z).
* **Higgs Boson (H⁰)** → gives mass to particles.
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# # # 8. Particle Accelerators & Detectors
* **Particle accelerators** (துணிக்கை வேகப்படுத்திகள்) → speed up particles close to speed of light for collisions. Example: **LHC (Large Hadron Collider)**.
* **Particle detectors** (துணிக்கை கண்டுபிடிப்பிகள்) → detect tracks, energy, and properties of particles. Examples: **Bubble chamber, Cloud chamber, Photomultiplier detectors**.
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# # # 9. Applications of Particle Physics
* **Medical imaging** (PET scan uses positrons).
* **Cancer treatment** (proton therapy).
* **Understanding early universe** (Big Bang conditions).
* **Development of technology** (e.g., World Wide Web at CERN).
