[5][6] During these fellowships, Schopper worked on nuclear physics and contributed substantially to the evidence of parity violation in weak interactions.

He measured the circular polarization of gamma rays following a beta decay, thought unfeasible by Lee and Yang,[7] and showed in the same experiment that the helicities of neutrino and antineutrino are opposite.

[8] In 1956, he followed Fleischmann to the University of Erlangen where he continued to do research in optics and solid-state physics, with emphasis on thin metal layers, which he had started at Hamburg.

In 1960–61 he worked under Robert R. Wilson at Cornell University to be introduced to elementary particle physics, namely the use of electron scattering to study the structure of the proton and neutron.

He also created a group at CERN to investigate neutron scattering at high energies at the Proton Synchrotron (PS) and Intersecting Storage Rings (ISR).

This facility allowed the verification of the standard model of particle physics, namely that it is a renormalizable field theory, leading to the award of the Nobel Prize to the theoreticians Veltman and t'Hooft.

Furthermore, it enabled the precise determination of fundamental parameters of the electroweak force, such as the W± and Z masses, and proved the existence of three neutrino families.

LEP was approved under the condition of a reduced and constant budget with the consequence that some unique activities at CERN (e.g. ISR) had to be abandoned.

At UNESCO, he served as member of the Physics Action Council and chairman of the Working Group on Large Facilities, president of the scientific council of the Regional Office for Science and Technology ROSTE of UNESCO in Venice (2001–2002) and in 2003–2009 he was the chairman of the international advisory committee for the International Basic Science Programs.

[25] SESAME was founded analogous to CERN, under the umbrella of UNESCO, with presently nine member states: Bahrain, Cyprus, Egypt, Iran, Israel, Jordan, Pakistan, the Palestinian Authority and Turkey.