Subatomic particle is the total number of nucleons (neutrons and protons collectively). Chemistry concerns itself with how electron sharing binds atoms into structures such as crystals and molecules. Nuclear physics deals with how protons and neutrons arrange themselves in nuclei. The study of subatomic particles, atoms and molecules, and their structure and interactions, requires quantum mechanics. Analyzing processes that change the numbers and types of particles requires quantum field theory. The study of subatomic particles "per se" is called particle physics. The term "high-energy physics" is nearly synonymous to "particle physics" since creation of particles requires high energies: it occurs only as
Evaporative cooling (atomic physics) group of Randall G. Hulet for lithium. Since then the technique has been improved upon, notably by Bouyer's team at Groupe d'Optique Atomique Laboratoire at the Charles Fabry Optical Institute. Evaporative cooling (atomic physics) Evaporative cooling is an atomic physics technique to achieve high phase space densities which optical cooling techniques typically can not reach. Atoms trapped in optical or magnetic traps are cooled as the trap depth is decreased and the hottest atoms (with the highest kinetic energy) leave the trap. The hot atoms leaving the trap are on the tail of the Maxwell-Boltzmann distribution and therefore carry away