The history of PSI

The following is a chronological review, including historical landmarks and a selection of highlights from the first 25 years of the Institute's existence.


  • On 1st January 1988, the Swiss Institute for Nuclear Research (SIN) and the Federal Institute for Reactor Research (EIR) were merged to form the Paul Scherrer Institute (PSI). The lower valley of the Aare thus became the location for a major research institute that would soon gain an international reputation.
  • The Institute was named after the Swiss physicist Paul Scherrer, who lived from 1890 to 1969. He taught and performed research at the ETH (the Swiss Federal Institute of Technology) and was well-regarded internationally, contributing greatly to the high standard of the natural sciences within Switzerland.
  • The enormous importance of PSI to science in Switzerland was clear from the prominent figures who took part in its inauguration. The expectations placed on the new institute by politicians and those responsible for education were extremely high.


  • New, future-oriented areas of research in solid-state physics, bio-medicine, renewable energy and environmental sciences were established at PSI after the merger. They were all able to benefit from the facilities available, some of which were the only ones of their kind in the world.
  • Construction of the SINQ neutron source began, which was an international innovation in large research facilities, and would offer new opportunities for the investigation of materials to researchers from all over the world. The 60 million CHF facility had been planned for a very long time and the merger now made sufficient resources available to complete the project within eight years.
  • Preparations began for upgrading the proton accelerator to 1MW operation.
  • Development of the General Energy Research Department: Solar chemistry, electro-chemistry and combustion research/laser diagnostics.


  • Anton Menth took over as the new Director on 1st April 1990, replacing Jean-Pierre Blaser.
  • Energy policy tug-of-war over the balance between nuclear and non-nuclear research.
  • Experimental verification of the Spot-Scanning technique for the subsequent irradiation of deep-seated tumours with a proton beam.
  • First-time application of Positron Emission Tomography to visualize biochemical processes in the body in the form of images.
  • PSI was involved at the very forefront of space research, building the detectors in the EUVITA telescope for the Russian Spectrum-X-G satellite. Later, PSI also supplied detectors to NASA and ESA, which were used to analyse cosmic radiation, thus opening new windows onto the universe.


  • Resignation of Director Anton Menth, Wilfred Hirt became Interim Director.
  • 1.5mA proton current achieved for the first time at Injector II, as well as 1mA in the ring cyclotron. This was a pre-requirement for a spallation neutron source (SINQ) that would be internationally competitive.
  • Establishment of a joint Institute for medical radio-biology with the University of Zurich, leading to world-wide recognition of its research on the diagnosis and treatment of cancer.
  • The 1000th patient with an eye tumour was treated at the OPTIS proton therapy facility.


  • Meinrad Eberle became the new Director. This ETH professor and mechanical engineer aimed to give PSI a clear identity as a research institute and user laboratory with a world-wide presence. The main emphasis was placed on particle physics and research into the structure of solids and bio-molecules, as well as in energy technology.
  • Tracers developed at PSI for medical PET studies led to internationally-recognised pharmacological discoveries towards a better understanding of Parkinson's disease.
  • The Swiss Federal Interim Storage Facility for low and intermediate level radioactive waste from medical, industrial and research activities (the BZL) was put into operation.
  • PSI also played its part in environmental research. The subject of air pollution was studied in depth through the examination of ice layers in the Arctic and on Alpine glaciers, as well as by measurements taken from balloons.
  • Combustion processes were also analysed at PSI in order to make it possible to construct low-emission heating systems and engines for vehicles.
  • Thanks to its extensive competence in materials research, PSI was regularly asked to investigate historical findings. For example, the radiocarbon method at the TANDEM accelerator was used to make a precise determination of the age of Ötzi – the Ice Mummy, found in 1991.
  • Construction starts at the large PANDA facility. The facility is intended to investigate passive safety systems for advanced light water reactors for nuclear power plants.


  • PSI opens its large research facilities to users from all over the world. The only determining factor is the quality of the research project. 50 percent of the users come from abroad, mostly from the EU.
  • The management of the fusion research activities at PSI was transferred to EPFL Lausanne.
  • The routine production of radioisotopes was transferred to industry and a new radiochemistry competence centre formed along with the University of Bern.
  • New fundamental physics discoveries were made regarding the polarisation of low-energy muons; muons then became attractive for use as probes for research into material surfaces and interfaces.
  • The pion therapy facility closed, after treating more than 500 tumour patients. The lessons learned, together with other new discoveries, made it possible to develop the PSI Spot-scanning radiation technique, which was unique in the world.
  • The new ETH law came into force and PSI became an autonomous research institution within the ETH domain.
  • First successes in the development of tumour-specific radiotherapy agents to combat micro-tumours.
  • New insight gained by use of the neutron scattering method into the origin of high-temperature superconductivity.


  • Our globalised society demands increasing mobility. For sustainable development, low-emission transport systems are vital, and PSI is part of the necessary research effort. PSI ran Energy Days, at which the two-kilowatt per person vision was introduced for the first time. New laboratories and research halls for energy research were inaugurated.
  • The aim of the PSI solar hydrogen project was to store solar energy. This valuable energy could then be used even when the sun was not shining.
  • The SAPHIR research reactor was closed down.
  • First summer school for neutron scattering was held in Zuoz. Since then, this has become an internationally-recognised point of contact between distinguished experts and young scientists.
  • Based on scientific discoveries, CO2 emissions were announced to be a problem requiring an urgent solution.
  • PSI X-ray and proton detectors were installed on satellites belonging to ESA and the Russian MIR station, providing the first highly accurate measurements of the changes in the radiation belts in the region of space close to the Earth caused by changes in solar activity.
  • New discoveries on the long-term stability of cement structures in marly ground water, which is important for the assessment of the radionuclide retention potential in permanent storage sites for radioactive waste.


  • The PSI proton accelerator had previously been used for particle physics studies. Today, the main emphasis is on applications for solid-state physics, radiopharmacy and cancer treatment. With this in mind, PSI successfully upgraded the accelerator to an extremely high level of performance.
  • Alongside surgery, radiation is the most important method of treating cancer. PSI developed a method of effectively destroying deep-seated tumours with protons. Radiopharmaceutical products that could track down and eliminate cancer cells were also developed.
  • The chemical properties of Element 106 (Seaborgium, Sg) were determined for the first time.
  • Important discoveries about CO2 balances in energy systems; this marked PSI out as a centre of competence for energy system analysis.


  • Leadership is increasingly required in the world of research as much as it is in the industrial world. The unique SINQ large research facility was formally inaugurated at PSI. This was the most powerful neutron source anywhere in the world, allowing scientists to undertake previously impossible experiments.
  • The nanotechnology laboratory was commissioned, enabling the first structures for the development of bio-sensors to be generated.
  • Highly efficient solar cells were developed, with a performance coefficient of 21.1 %.
  • The Swiss Federal Council passed a resolution to implement a new large research facility at PSI, the Swiss Light Source SLS, and passed their dispatch on to Parliament.
  • The first cancer patient was treated with proton radiation using the spot-scanning technique (at the PSI gantry) – again, the only one of its kind in the world.
  • A new clean-room complex was commissioned. In subsequent years, this complex became the venue for developments such as new types of highly-efficient solar cells.


  • Both chambers of the Swiss Federal Parliament approved the construction of the Swiss Light Source (SLS).
  • New discoveries relating to magnetic fluids were made with the help of neutron scattering at the SINQ facility.
  • A high-power solar furnace was commisioned which would be used to study high temperature processes for the chemical storage of solar energy.
  • Transfer of PSI's external branch in Zurich to the Swiss Center for Electronics and Microtechnology (CSEM) in Neuchâtel.
  • Notable Swiss companies set up SLSTechno-Trans AG to exploit the future innovations resulting from research at SLS.


  • Building work started on the SLS. The construction of the innovative large facility Swiss Light Source SLS made PSI even more recognisable from the air than before. The SLS cost 180 million CHF and can be used as a kind of giant microscope, allowing researchers to penetrate hitherto inaccessible depths of the microcosmos. It could, for example, be used to develop pharmaceutical products or new materials.
  • New discoveries about the magnetic properties of materials were made at SINQ, and the results used in the development of magnetic storage media in the information technology field.
  • A 1kW fuel-cell stack achieved a service life of 10,000 hours, while supercapacitors achieved 100,000 charging and discharging cycles, thus satisfing the basic requirements for application in a road-going vehicle.
  • New discoveries were made on the vertical transport of ozone in Alpine valleys; high Alpine regions are significantly more badly affected by the increase in trans-Alpine traffic than had previously been thought.
  • PSI celebrates its 10th anniversary by opening the PSI Forum visitor centre in order to promote the dialogue between science and society. The instructive, interactive exhibition of the areas covered by PSI's research activities was mainly aimed at the younger generation. The 3-D film A Journey to the Centre of Matter became a particular attraction.


  • An increase in beam current at the ring accelerator made SINQ the only source anywhere in the world with a spallation target in the MW range.
  • The radiochemical element Bohrium was examined for the very first time, with only six atoms available.
  • The Energie-Spiegel was launched, which was to become one of the most highly regarded publications in the Swiss energy sector in subsequent years.
  • The 20,000th visitor was recorded at the PSI Forum.
  • Knowledge and skill are important prerequisites for the success of the whole economy, as well as for each individual person. Switzerland depends on well-trained specialists and, as its contribution to this, PSI annually trains 240 postgraduate students and 80 apprentices. It ran a number of special training courses and supported the teaching activities of its specialist staff.
  • An Open Day was organised, to keep the general public informed. More than 6,000 people visited the facilities, viewed the laboratories and received explanations from PSI specialists about their own areas of research.


  • Nuclear energy continues to be an option in Switzerland. At PSI, nuclear energy research concentrates on safety aspects: on reactor concepts with even more inherent safety; on the behaviour of materials in nuclear reactors; and on the safe disposal of radioactive waste.
  • Synchrotron light was generated at the SLS for the first time.
  • The PROSCAN project started (the development of proton therapy); charities and private donors supported the project to the tune of over 8 million CHF in subsequent years, while the Canton of Aargau provided in addition a loan of 5 million CHF.
  • Development started on new catalytic processes to convert biomass into synthetic natural gas.
  • Start-up of low-energy muon beam production, enabling magnetic domains in non-magnetic metals to be seen for the first time.


  • Inauguration of the SLS on 19th October, in the presence of Federal Councillor Ruth Dreifuss.
  • Specification and procurement of a compact superconducting cyclotron (COMET) for proton therapy.
  • Initial test runs of the VW Bora HY.Power car, equipped with fuel cells and supercapacitors for braking-energy regeneration; this vehicle travelled over the Simplon Pass in January 2002.
  • Expedition by a research team into the Altai Mountains in Siberia; analysis of glacial ice revealed a marked increase in temperature in this region over the past 150 years.


  • Ralph Eichler became the new Director. The vision of this ETH professor and experimental particle physicist was to build a free-electron laser to investigate tiny structures in an extremely short time.
  • The NASA satellite HESSI was launched, carrying an X-ray telescope from PSI on board, to observe high-energy solar activity.
  • A second SLS beamline for protein crystallography was inaugurated and taken into service (with participation from Novartis, Roche and the Max-Planck Society).
  • Open Day: Surfaces – familiar and unfamiliar interfaces, with 5,500 visitors.


  • The Paul Scherrer Institute is very well integrated in the international science scene, and is globally welcomed as a partner. PSI led the development of giant detectors for current physics experiments at the CERN European Research Laboratory in Geneva.
  • Preliminary work started on the SwissFEL, the new large research facility, an X-ray laser which uses extremely short pulses of radiation.
  • Megamolecules from sunlight. Results from the new smog chamber caused a stir and established this test device as a research facility that was highly regarded internationally. This propelled PSI's aerosol research (including its studies on the Jungfraujoch) into the limelight.
  • The XIL (X-ray Interference Lithography) beam line was commissioned at the SLS, with which high-precision nanostructures could be created (a world record!).
  • Open Day: A glimpse into the world of the future for 6,000 people with a thirst for knowledge.
  • For the first time, more than 1500 external scientists used the large research facilities at PSI during the course of the year.


  • The COMET superconducting compact medical cyclotron arrived. For the first time in Europe, infants suffering from cancer could benefit from proton therapy (under anaesthetic) and gain a significantly improved chance of survival.
  • The lightweight HY-LIGHT fuel cell car (2-litre petrol-equivalent /100km) produced jointly by PSI and Michelin underwent successful demonstration testing in Shanghai.
  • Celebrations were held for the 30-year anniversary of the ring accelerator. The machine still continues to be at the forefront of technology internationally.
  • Thanks to genome information, researchers at the SLS were able to study protein structures that may be connected to various diseases, which might at some stage lead to tailor-made medication. The demand for these investigations is extremely high and the SLS is therefore being continuously expanded and developed.


  • The PSI/ETHZ pilot plant at the 300kW scale, to generate solar high-temperature process heat, was commissioned in Israel.
  • The decision was taken to build a 1MW pilot plant to obtain methane from wood.
  • Development of the promising Phase-Contrast microscopy facility.
  • PSI organised the European Research Centres' Winter Olympics at Disentis-Sedrun.
  • Swiss Technology Award received for the selective catalytic exhaust gas treatment system (the SCR System).
  • The premiere at the PSI Forum of the award-winning 3-D film Around the World in 80 Million Years, describing the carbon cycle.
  • PSI offered tours to interested groups showing the impact of Einstein's research at PSI. More than 9,000 people visited PSI on its Day of Physics Open Day – a new record.


  • Technically, it is possible to solve the problem of the disposal of nuclear waste by permanent geological storage. However, it would be more elegant to convert long-lived radioactive atomic nuclei into radioactive atomic nuclei with a short half-life. The development of the MEGAPIE liquid metal neutron spallation target at PSI offered a possible concept for doubling the output of the SINQ neutron source as well as the conversion of long-lived nuclear waste using this tool.
  • Thanks to this doubling of output, the neutron source became even more attractive to researchers. New research instruments were incorporated to cater for additional experiments.
  • The ETH Board transferred the leadership of the Swiss Competence Center for Energy and Mobility (CCEM) to PSI, and the Canton of Aargau granted a loan of 10 million CHF to the Center.
  • The TOMCAT (with EPF Lausanne) and POLLUX (with the University of Erlangen-Nuremberg) beamlines were commissioned for SLS users.
  • The femtosecond undulator source at the SLS began operation, enabling short-exposure images of lattice vibrations in crystals to be taken with a very high resolution.
  • World-wide recognition was achieved for new results in superconductivity research (achieved with low-energy muons) and in molecular biology (control of vascular tissue-forming cells).
  • Development of the large components for Gantry 2 (proton therapy equipment for the irradiation of tumours which move following respiration, e.g. lung and breast carcinoma); the Canton of Aargau gave a grant of 1 million CHF for proton therapy.


  • PSI Director Ralph Eichler moved over to become President of ETH Zurich; ETH physicist Martin Jermann was appointed Interim Director.
  • 10th anniversary of SINQ was celebrated with a colloquium and a Neutron Day for the general public. The proton beam at the ring accelerator was upgraded to a new record level of 2.16mA (1.3MW).
  • Patient irradiation began at the COMET superconducting cyclotron, and a changeover was made to year-round proton therapy operation, and the successful irradiation, under anaesthetic, of 15 infants suffering from cancer took place.


  • “20 Years PSI” celebrated with numerous events for the public, including a two-day open day where around 12,000 visitors experienced the institute's research at first hand.
  • Launch of the PSI-XFEL (now SwissFEL) project with the construction of a 70-meter experimentation hall for the installation of the 250 MeV electron accelerator test facility.
  • Inauguration of the iLab lab school with the goal of inspiring young people to take up a career in a scientific environment.
  • Beginning of the collaboration between the PSI and Swatch/Belenos AG to develop fuel cell drives for automobiles.
  • Joël Mesot becomes the new director of the PSI on 1 August 1 2008, setting the increased networking between the PSI and Swiss universities, closer collaboration with industry, the preservation of the international competitive ability of the existing large research facilities and the realisation of the future project SwissFEL as priorities.
  • “20 Years PSI” ceremony in the presence of President of the Federal Council Pascal Couchepin and over 200 invited guests.


  • A new procedure for the production of synthetic natural gas from wood is tested successfully, earning the research team from the PSI the Watt d'Or in 2009.
  • Experiments conducted at the PSI's large research facilities shed new light on superconductors and their properties.
  • Venkatraman Ramakrishnan is a long-standing user of the SLS at the PSI, regularly conducting experiments here to determine the structures of ribosomes. The same year, he is awarded the Nobel Prize for Chemistry for these structural determinations.
  • The first PSI Thesis Medal is awarded to an outstanding doctoral thesis by a user of the large PSI research facilities. From now on, the prize is to be awarded every two years when the PSI user community convenes at the institute.
  • The laboratory for neutron scattering celebrates its 25th birthday.


  • DECTRIS, a PSI spin-off in the field of x-ray pixel detectors, receives the 2010 Swiss Economic Award for Start-Up Companies.
  • Experiments at the PSI reveal that the radius of a proton is smaller than previously believed, which could affect our understanding of the origins of the universe. The results rank among the top ten findings of the year.
  • The entire Federal Council visits the PSI.
  • Inauguration of the 250 MeV electron accelerator test facility for the SwissFEL in the presence of Federal Councillor Didier Burkhalter and Swissmem President Johann Schneider-Ammann.
  • 25 years of treating eye tumours with proton beams and the inauguration of the new radiotherapy ward OPTIS 2. Over 5,500 patients with eye tumours have been treated successfully with proton therapy at the PSI thus far.


  • The PSI demonstrates for the first time that syngas, a precursor in the production of petrol or kerosene, can be produced from water and CO2 with the aid of highly concentrated solar radiation. The PSI researchers were presented with the Golden Idea Award by IDEE-SUISSE®.
  • Basic structure of sight decoded. A team of researchers at the PSI succeeds in determining the structure of the key protein rhodopsin in a short-lived, excited state.
  • The site for the construction of the SwissFEL facility in Würenlinger Unterwald is approved by the Aargau Government Council and Parliament.
  • The SLS turns ten. The research results from this period have yielded over 2,000 scientific publications in the fields of chemistry, physics and biology and been channelled into many industrial applications, especially in the pharmaceutical industry. The SLS started out with 4 beam lines; 10 years on, it has 18.
  • The UCN facility produces ultra-cold neutrons for the nEDM experiment for the first time with a view to measuring the neutron's electric dipole moment.


  • The PSI teams up with the World Energy Council to develop energy models to calculate global energy systems.
  • Collaboration agreement signed with Swiss industry for the high-precision production of accelerator structures for SwissFEL, for which the PSI provides industry with its technological knowhow.
  • The PSI invites guests to an energy conference: representatives from politics, industry and research discuss with Federal Councillor Doris Leuthard.
  • A technique developed at the PSI for the retention of radioactive iodine aerosols in the event of an accident at a nuclear power station is licensed for further marketing at a Swiss industrial company.
  • Physicists from the PSI observe the splitting of an electron in a solid body for the first time. The results should help understand superconductivity better.
  • A mammography method developed at the PSI in collaboration with Baden Cantonal Hospital and Philips yields clear added value for the diagnosis of breast cancer.
  • The measurements on diesel particle filters carried out at the SINQ with neutron radiography attract a lot of attention in the automobile world.


  • Foundation of the Institute of Biomass and Resources Efficiency by the two institutions PSI and University of Applied Sciences and Arts Northwestern Switzerland.
  • Laying of the foundation stone for the new large research facility SwissFEL.
  • An electronics student at the PSI wins the gold medal at WorldSkills Leipzig 2013.
  • The Canton of Aargau and the PSI present the concept of PARK innovAARE as a potential network location for the Swiss Innovation Park.
  • Researchers from the PSI gain key insights into sodium-ion batteries, the memory effect of lithium-ion batteries and fuel cells based on novel aerogel catalysts.
  • Youth day with experiments and lectures for 2,500 children, teenagers and the young at heart.
  • The Nobel Prize is awarded for the theoretical prediction of the Higgs particle, which is responsible for the formation of mass. One year earlier, Higgs particles were actually detected for the first time at CERN. The pixel detector that made this possible was largely developed and constructed at the PSI in a 16-year project.

This is a chronological retrospect on PSI's historical milestones and a selection of its highlights during its first 25 Years. Our press releases report on current highlights.