1950-1960


1951 
Beginning and development of quantum electronics - Ch.H. Townes, W.A. Fabrikant, J. Weber, J.P. Gordon, H.J. Zeiger, N.G. Basow, A.M. Prochorow, T.H. Maiman

The American physicist Charles H. Townes, and Soviet physicists Alexander Mikhailovich Prokhorov & Nikolai Gennadiyevich Basov, independently suggest a way of inducing molecules to emit intense, coherent microwaves. Townes goes on to build and name the first maser (Microwave Amplification by Stimulated Emission of Radiation). It allowed to built first masers (1954) and lasers (1960).

1952
Discovery of hypernuclei - M. Danysz, J. Pniewski

In 1952 Professors Danysz and Pniewski observed a cosmic ray interaction in emulsion, in which one of the nuclear fragments contained a hyperon. Such fragments were called hyperfragments. In other words, a hyperfragment (or hypernucleus) is a nucleus in which one or more nucleons are replaced by hyperons.

1956
Experimental confirmation of antinucleons (antiprotons) existence - E.Segre, 0. Chamberlain i in., antyneutrony - B. Cork i in.)
Discovery of breaking of parity rule in weak interactions and C-T symmetry - D. Lee, C.N. Yang, C.S. Wu, L.M.Lederman i in.
1957 
Discovery of  Mössbauer effect - R.L. Mössbauer

The resonant emission and absorption of x-rays by gases had been observed previously, and it was expected that a similar phenomenon existed for gamma rays, which are created by nuclear transitions (as opposed to x-rays, which are produced by electronic transitions). However, attempts to observe gamma-ray resonance in gases failed due to energy being lost to recoil, preventing resonance. Mössbauer was able to observe resonance in solid iridium, which raised the question of why gamma-ray resonance was possible in solids, but not in gases. Mössbauer proposed that, for the case of atoms bound into a solid, under certain circumstances a fraction of the nuclear events could occur essentially without recoil. He attributed the observed resonance to this recoil-free fraction of nuclear events.

1958 
Weak interactions theory - R.P. Feynman, M. Gell-Mann

E. Fermi was first to describe weak interactions in the 1930s. While formulating his theory he referred partly to quantum theory of electromagnetic field, in other words, to quantum electrodynamics. Such an approach caused certain difficulties which were resolved by a new general theory of weak interactions between electrically charged particles proposed by R.P. Feynman and M. Gell-Mann in 1958.