First polarised proton beam Circular polarisation of gamma-rays following beta decay Hadron calorimeter Superconducting cavities High energy e-p scattering
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. Later, he was involved in an experiment to test time reversal symmetry.[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. Also he developed, along with Clausnitzer, the first source of polarised protons.[9] In 1957 he became Privatdozent at the University of Erlangen.[6]
From 1958 to 1961, Schopper was an associate professor at the University of Mainz where he established the Institute for Experimental Nuclear Physics. 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.[10]
Schopper was appointed professor at the University of Karlsruhe in 1961 and director of the newly established Institutes for Experimental Nuclear Physics of TH Karlsruhe and the Karlsruhe Nuclear Research Centre.[11] In order to continue his research on electron scattering he set up a group to carry out one of the first experiments at DESY. He also created a group at CERN to investigate neutron scattering at high energies at the Proton Synchrotron (PS) and Intersecting Storage Rings (ISR). These experiments where then continued at the Institute for High Energy Physics (IHEP) in Serpukhov, Russia. The group made important contributions to the study of neutron-proton and neutron-nuclei scattering cross sections.[12] For this purpose, the first hadron calorimeter was developed and optimised by Monte Carlo simulations.[13] Another group at Karlsruhe developed the first superconducting high frequency cavities in Europe, a technology which was transferred to CERN for particle separators and later for particle acceleration at LEP.
At CERN, he was a research associate in 1966–67, became division leader of the Nuclear Physics Division in 1970, member of the directorate responsible for the co-ordination of the experimental programme until 1973 and chairman of the ISR Committee from 1973 to 1976.[14]
In 1973 Schopper became professor at the University of Hamburg and the chairman of the directorate of DESY, serving until end of 1980.[4] He was responsible for the installation of the ARGUS detector at DORIS which later resulted in the first evidence of B – B bar mixing.[15] Also, by establishing HASYLAB at DORIS synchrotron light science became an important branch of research at DESY. He proposed and completed the construction of the electron-positron collider PETRA which led to the discovery and study of the gluon.[16][17] During his mandate, DESY, a national laboratory became as far as science was concerned an international particle physics laboratory. This included the start of the first collaboration with China.
After being member of the Scientific Policy Committee at CERN, Schopper was elected director general and served from 1981 to 1988.[18][6] His first task was to unite the two CERN laboratories existing at that time under two Directors General. The Large Electron–Positron Collider (LEP) was also proposed and constructed under his leadership. 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.[19] Thus, this particle accelerator transformed high energy physics into a field of precision measurements and provided estimates to the mass of the top quark, Higgs boson and other supersymmetric and hypothetical particles. 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. Schopper was obliged to introduce a new way of international collaboration for the four LEP experiments since CERN could not provide funds for them. The experiments became rather independent activities organised in a rather democratic way bringing together hundreds of scientists from many universities and national organisations.[20] The LEP experiments became a model for the later LHC experiments, shaping the way this organization works today. He contributed to the globalisation of research at CERN and was also responsible for the return of Spain and Portugal in the CERN's member states.[21]
Schopper at the Second International Conference on Research and Communications in Physics
Schopper is professor emeritus at the University of Hamburg since 1989.[4] From 1992 to 1994 he was president of the German Physical Society and president of the European Physical Society in 1995–97.[22] For many years he was member of the scientific council of the Joint Institute for Nuclear Research in Dubna and of the board of trustees of the Max Planck Institute for Plasma Physics in Garching.
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.[23]
Schopper's vision of science without borders resulted in him becoming a founding father of SESAME, the laboratory for Synchrotron-Light for Experimental Science and Applications in the Middle East, which provides an extremely bright light source to investigate a broad range of domains from condensed matter to biology and archeology.[24] In 1999–2008 he became president of the Preliminary International Council and later, after the formal foundation of SESAME, of the International Council. Without his dedication this international research facility would probably not have been built.[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. It provides an environment where countries with different political systems, traditions, religions and mentalities are able to work together peacefully.
Schopper is a founding member of The Cyprus Institute at Nicosia, Cyprus, and since 2000 Member of the board of trustees and was chairman of the Scientific Council and member of the executive committee of the board of trustees of the Cyprus Institute.[26]
Currently, he works as an advisor and goodwill ambassador on science for peace. He writes articles about research policy, science and religion and also science and society.
Schopper wrote more than 200 original publications in optics, nuclear physics, elementary particle physics and accelerator technology. Some of the most important works are:
Fleischmann R. and H. Schopper, The determination of the optical constants and thickness of the layer of absorbent layers by means of the measurement of the absolute phase change Z.Physik 129.285 (1951) (first method for the measurement of the absolute phase upon reflection of light on the thin metal layers)
H. Schopper, The interpretation of the optical constants of alkali metals, Z.Physik 135, 163 (1953) (the abnormal optical behaviour of thin alkali metal layers does not require a special physical state of the metal)
H. Schopper, Circular polarization of gamma rays: Further proof for parity failure in beta-decay, Phil.Mag.' 2, 710 (1957) (One of the experiments proposed by Lee and Yang, but considered impossible. In this experiment it was shown for the first time that the helicity of the neutrino and antineutrino are opposite.)
G. Clausnitzer, R. Fleischmann and H. Schopper, Production of a hydrogen atom beam with parallel nuclear spins, Z.Physik 144, 336 (1956)
H. Schopper and S. Galster, The circular polarization of internal and external bremsstrahlung, Nucl.Phys. 6, 125 (1958) (first measurement of the circular polarization of the internal bremsstrahlung of beta decay)
J. Halbritter, R. Hietschold, P. Kneisel, and H. Schopper, Coupling losses and the measurement of Q-values of superconducting cavities, KFK-report Karlsruhe 3 / 86-6 (1968) (early publication of the study of superconducting cavities to accelerate particles)
R. M. Littauer, H. Schopper, R. R. Wilson, Electromagnetic properties of the proton and neutron, Phys. Rev. Lett. 6, 286 (1961), Phys. Rev. Lett. 7, 141 (1961) and 7, 144 (1961) (measurement of nuclear form factors, improvement of the first measurements by R. Hofstadter)
Behrend et al., Elastic electron-proton scattering at momentum transfers up to 110 fermi-2, Nuov.Cim. 48.140 (1967)
J. Engler, W. Flauger, AS. Gibbard, F. Mönnig, K. Runge and H. Schopper, A total absorption spectrometer for energy measurements of high-energy particles, Nucl.Instr.Meth. 106, 189 (1973) (first usage and optimization of a 'hadron calorimeter')
V. Boehmer et al., Neutron-proton elastic scattering from 10 to 70 GeV / c, Nucl.Phys. B91, 266 (1975) and other publications (neutron-proton scattering at high energies, the ISR at CERN and at the Institute for High Energy Physics in Protvino, Russia)
L3 Collaboration, Upsilon production in Z decays, Phys.Lett. B 413, 167 (1997) and Heavy Quarkonium Production in Z decays, CERN-PPE/92-99 and Phys.Lett.B (Schopper was principal author of these publications)
H.Schopper, The light of SESAME: A dream becomes reality, La Rivista del Nuovo Cimento, 40, 199 (2017)
A gluon is a type of massless elementary particle that mediates the strong interaction between quarks, acting as the exchange particle for the interaction. Gluons are massless vector bosons, thereby having a spin of 1. Through the strong interaction, gluons bind quarks into groups according to quantum chromodynamics (QCD), forming hadrons such as protons and neutrons.
Particle physics or high-energy physics is the study of fundamental particles and forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the scale of protons and neutrons, while the study of combination of protons and neutrons is called nuclear physics.
The European Organization for Nuclear Research, known as CERN, is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in Meyrin, western suburb of Geneva, on the France–Switzerland border. It comprises 24 member states. Israel, admitted in 2013, is the only non-European full member. CERN is an official United Nations General Assembly observer.
DESY, short for Deutsches Elektronen-Synchrotron, is a national research centre for fundamental science located in Hamburg and Zeuthen near Berlin in Germany. It operates particle accelerators used to investigate the structure, dynamics and function of matter, and conducts a broad spectrum of interdisciplinary scientific research in four main areas: particle and high energy physics; photon science; astroparticle physics; and the development, construction and operation of particle accelerators. Its name refers to its first project, an electron synchrotron. DESY is publicly financed by the Federal Republic of Germany and the Federal States of Hamburg and Brandenburg and is a member of the Helmholtz Association.
HERA was a particle accelerator at DESY in Hamburg. It was operated from 1992 to 30 June 2007. At HERA, electrons or positrons were brought to collision with protons at a center-of-mass energy of 320 GeV. HERA was used mainly to study the structure of protons and the properties of quarks, laying the foundation for much of the science done at the Large Hadron Collider (LHC) at the CERN particle physics laboratory today. HERA is the only lepton–proton collider in the world to date and was on the energy frontier in certain regions of the kinematic range.
The ISOLDE Radioactive Ion Beam Facility, is an on-line isotope separator facility located at the centre of the CERN accelerator complex on the Franco-Swiss border. Created in 1964, the ISOLDE facility started delivering radioactive ion beams (RIBs) to users in 1967. Originally located at the Synchro-Cyclotron (SC) accelerator, the facility has been upgraded several times most notably in 1992 when the whole facility was moved to be connected to CERN's ProtonSynchroton Booster (PSB). ISOLDE is currently the longest-running facility in operation at CERN, with continuous developments of the facility and its experiments keeping ISOLDE at the forefront of science with RIBs. ISOLDE benefits a wide range of physics communities with applications covering nuclear, atomic, molecular and solid-state physics, but also biophysics and astrophysics, as well as high-precision experiments looking for physics beyond the Standard Model. The facility is operated by the ISOLDE Collaboration, comprising CERN and sixteen (mostly) European countries. As of 2019, close to 1,000 experimentalists around the world are coming to ISOLDE to perform typically 50 different experiments per year.
Jonathan Richard "John" Ellis is a British-Swiss theoretical physicist.
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Sau Lan Wu is a Chinese-American particle physicist and the Enrico Fermi Distinguished Professor of Physics at the University of Wisconsin-Madison. She made important contributions towards the discovery of the J/psi particle, which provided experimental evidence for the existence of the charm quark, and the gluon, the vector boson of the strong force in the Standard Model of physics. Recently, her team located at the European Organization for Nuclear Research (CERN), using data collected at the Large Hadron Collider (LHC), was part of the international effort in the discovery of a boson consistent with the Higgs boson.
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The discovery of the neutron and its properties was central to the extraordinary developments in atomic physics in the first half of the 20th century. Early in the century, Ernest Rutherford developed a crude model of the atom, based on the gold foil experiment of Hans Geiger and Ernest Marsden. In this model, atoms had their mass and positive electric charge concentrated in a very small nucleus. By 1920, isotopes of chemical elements had been discovered, the atomic masses had been determined to be (approximately) integer multiples of the mass of the hydrogen atom, and the atomic number had been identified as the charge on the nucleus. Throughout the 1920s, the nucleus was viewed as composed of combinations of protons and electrons, the two elementary particles known at the time, but that model presented several experimental and theoretical contradictions.
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↑ Engler, J.; Horn, K.; Mönnig, F.; Schludecker, P.; Schmidt-Parzefall, W.; Schopper, H.; Sievers, P.; Ullrich, H.; Hartung, R.; Runge, K.; Galaktionov, Yu (11 May 1970). "Neutron-proton total cross-sections between 8 GeVc and 21 GeVc". Physics Letters B. 31 (10): 669–672. Bibcode:1970PhLB...31..669E. doi:10.1016/0370-2693(70)90031-6.
↑ Engler, J.; Flauger, W.; Gibbard, B.; Mönnig, F.; Runge, K.; Schopper, H. (1 January 1973). "A total absorption spectrometer for energy measurements of high-energy particles". Nuclear Instruments and Methods. 106 (1): 189–200. Bibcode:1973NucIM.106..189E. doi:10.1016/0029-554x(73)90063-3.
↑ Schopper, Herwig (2009). "What Have We Learned from LEP? – Physics Results". LEP The Lord of the Collider Rings at CERN 1980-2000: What Have We Learned from LEP? - Physics Results. Geneva, Switzerland: Springer. pp.113–142. doi:10.1007/978-3-540-89301-1_8. ISBN978-3-540-89300-4.
↑ Schopper, Herwig (2009). "The Approval, or How to Persuade Governments". LEP The Lord of the Collider Rings at CERN 1980-2000: The Approval, or How to Persuade Governments. Geneva, Switzerland: Springer. pp.19–30. doi:10.1007/978-3-540-89301-1_3. ISBN978-3-540-89300-4.
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