Neutron particle physics happens at energies many orders of magnitude below what is delivered by accelerators. Yet it can provide important information of physics in and beyond the Standard Model of particle physics. I will discuss different experiments, their peculiarities and implications. The course of the lectures is as follows:
(1) Neutron decay in the Standard Model and its meaning for astrophysics,
(2) Symmetry tests as a quest for physics beyond the Standard Model:
additional CP violation, baryon number non-conservation and right-handed currents,
(3) Quantum states of neutrons in the gravitational field and their application in searches for new physics.