Rutherford's Experiment and Particle Physics

Historical Context

At the time of Rutherford's experiment, the atom was thought to be a blob of positive charge with negative electrons embedded inside it.

Objective: Direct a beam of alpha particles through a thin gold foil to study atomic structure.
Alpha Particles: Known to be heavy, positively charged particles (now known as helium nuclei).
Setup:
- Brass can containing americium-241 source produces alpha particles.
- Alpha particles pass through a gold foil approximately 1.5 microns thick.
- Two detectors used to measure particles:
  - One detects particles going straight (majority).
  - The second measures scattering rate as a function of angle.

Most alpha particles go straight through, indicating atoms are mostly empty space.
Occasional deflections occur when particles come close to gold nucleus:
- Glancing blows cause small-angle deflections.
- Head-on collisions cause particles to bounce back.
Observations required meticulous and laborious measurement methods.

Structure of Atom:
- Atom consists of a heavy nucleus with mostly empty space.
- Electrons distributed around the nucleus.
Significance:
- Changed the understanding of atomic structure.
- Marked the beginning of particle physics.
Methodology:
- Beam of particles fired at a target to study internal structure through scattering behavior.

From Rutherford to Modern Physics:
- Original apparatus was desk-sized.
- Modern equivalent: Large Hadron Collider (LHC), 27 km in circumference.
- LHC collides beams of particles to study scattering and deduce collision processes.

Atom: Mostly empty space with a small, dense nucleus.
Particle Scattering: Technique to study subatomic structures by analyzing deflection patterns of particles.

Rutherford's experiment laid the foundation for modern particle physics and techniques used in facilities like the LHC.