# [SCI] Nuclear Physics

**Nuclear Physics** is the study of atomic nuclei — their structure, reactions, and the forces binding protons and neutrons — leading to fission, fusion, and the understanding of stellar energy.

## Overview

James Chadwick discovered the neutron (1932), completing the nuclear model. Enrico Fermi demonstrated neutron-induced radioactivity (1934). Otto Hahn, Lise Meitner, and Fritz Strassmann discovered nuclear fission (1938). Fermi achieved the first controlled chain reaction (Chicago Pile-1, 1942). The binding energy per nucleon explains why fission of heavy nuclei and fusion of light nuclei both release energy (E = mc²). Nuclear physics underpins nuclear power, nuclear medicine (PET, radiotherapy), nuclear weapons, and stellar astrophysics.

## Key Figures & Recognition

- **James Chadwick** (1891–1974): Discovery of neutron. **Nobel Prize 1935**.
- **Enrico Fermi** (1901–1954): Neutron-induced fission, first reactor. **Nobel Prize 1938**.
- **Otto Hahn** (1879–1968): Discovery of fission. **Nobel Prize 1944** (controversially, without Meitner).
- **Lise Meitner** (1878–1968): Co-discovered fission, provided theoretical explanation. No Nobel (widely considered an injustice).

## Seminal Papers

- Chadwick, J. "Possible Existence of a Neutron." *Nature* 129 (1932).
- Hahn, O. & Strassmann, F. "Über den Nachweis und das Verhalten der bei der Bestrahlung des Urans entstehenden Erdalkalimetalle." *Naturwissenschaften* 27 (1939).
- Meitner, L. & Frisch, O.R. "Disintegration of Uranium by Neutrons." *Nature* 143 (1939).

## What This Enables

- **[SCI] Nuclear Magnetic Resonance (NMR)** — Nuclear spin precession in a magnetic field — the NMR effect — is a direct consequence of nuclear quantum mechanics.
- **[TECH] Nuclear Power Generation** — Controlled fission chain reactions are applied nuclear physics, exploiting the Q-value of ²³⁵U fission.
- **[TECH] Medical Imaging (X-ray, CT, PET)** — X-rays (Röntgen), radioactive tracers (PET/SPECT), and nuclear medicinegamma cameras all draw on nuclear physics.

# Parents

* [SCI] Quantum Mechanics
* [SCI] Special Relativity
* [SCI] Quantum Mechanics