Science with neutrons and muons Research at the Paul Scherrer Institute An experiment with muons is being prepared. Contents 4 Neutrons and muons 18 Discovering materials in 90 seconds 18 Microgels 19 Making smart materials 6 Energy and transport 19 Understanding superconductors 6 Seeing batteries from the inside 20 Engaging with industry 6 Refining motorcycle fuel efficiency 7 Stress-testing turbine blades 20 Universities, industry and PSI 21 Solving industry problems 21 Developing new technologies 8 Earth and environment 21 Spin-off company 8 Cleaning soil with poplar trees 21 A future neutron source for Europe 8 Water in clays 9 Watching plants grow 22 Inside the Swiss Muon Source SμS 10 Food, health and medicine 24 Using neutrons and muons 10 Secret life of bubbles 25 What is a neutron? 10 A recipe for healthy eating 25 What is a muon? 11 Copying nature for medicine 26 Making neutrons and muons 12 Inside the Swiss Spallation 26 Accelerating protons Neutron Source SINQ 26 Making neutrons 26 Making muons 14 Heritage and culture 14 Making a Bronze Age axe 28 We make it work 15 Predicting salt damage to buildings 31 PSI in brief 16 Electronics and technology 1 3 Imprint 16 Spintronics 31 Contacts 16 Measuring grains of magnetism 17 Molecular sandwiches Cover photo Experiments with neutrons and muons allow scientists to measure inside materials and find out where atoms are and what they are doing. 3 Neutrons and muons in 90 seconds The Paul Scherrer Institute PSI, is Neutrons are abundant particles in home to three large research facilities: nature. Along with protons and elec- the Swiss Spallation Neutron Source trons, they make up atoms, the basic SINQ, the Swiss Muon Source SμS, and building blocks of the natural world. the Swiss Light Source SLS. PSI is the Neutrons are tightly bound up with largest natural and engineering protons in the nucleus at the centre of sciences research centre in Switzer- an atom. land. Muons are elementary particles that can be embedded in the gaps between atoms inside a material to sense what Using the large research facilities at is around them. They have an electric PSI, scientists can get an outstanding charge and are heavier than an electron view of the inside world of materials. but lighter than a proton. Their measurements connect the mi- croscopic positions and movement of Over 2500 scientists travel to PSI every atoms with the properties experienced year from Switzerland and around the in the everyday world. world. Among others they use the beams of neutrons and muons to illu- The comforts and convenience of mod- minate their materials and discover ern life rely on many decades of re- their microscopic properties. search and development by scientists and engineers. Through their careful Every day, discoveries from PSI are explorations, the potential uses of nat- being used to advance science and ural and artificial materials can be re- solve problems in industry. alised. You can read more about PSI research Materials are everywhere. Lightweight using neutrons or muons in the follow- bikes and fuel-efficient cars, surgical ing pages. implants, energy efficient homes, car- rying fresh food from supplier to super- market every day, mobile phones for instant connection to family and friends, and much more. http://psi.ch/X135 At PSI, beams of neutrons and muons are used for materials research. The beams are made by firing protons from a particle accelerator into targets made of lead or carbon. A fantastic piece of Swiss engineering, the accelerator http://psi.ch/HkxX makes the most powerful beam of pro- tons in the world. 4 The comforts and convenience of modern life would be impossible without many decades of research into new materials. 5 Energy and transport As demand for energy continues to Using neutron beams, it is possible to in volume would make it very difficult increase, ways to reduce fuel consump- see inside a battery and follow what is to guarantee the battery would work tion and improve energy efficiency are happening in real time to the battery after it had been charged many times. a growing concern. Neutron and muon parts as it is charged and discharged. beams at PSI are increasingly being This gives unique insight into the real used for energy related research. operating performance of the battery. Refining motorcycle fuel With muon beams, the movement of efficiency chemicals around the battery can be followed. Neutron beams can shine right through Seeing batteries from the For instance, the microscopic changes metals. This property has been put to inside to the volume of a metal hydride can good use by engineers designing a be watched as hydrogen is absorbed clutch lubricated with oil. To their sur- Rechargable batteries are used every- during charging. Good commercial ma- prise, many discs were found to be where in toys, electronics and electric terials have a smooth and reversible running dry. Time to go back to the vehicles. Common nickel-metal hy- change in volume. But if a possible new drawing board. dride batteries were once just labora- battery material makes a sudden jump tory curiosities. Now, materials devel- in volume rather than a smooth change, Motorcycle engineers are under con- oped in the last 20 years allow them it is not suitable. Such sudden changes stant pressure to reduce fuel consump- to be recharged many times. Battery development is a continuous process and neutron and muon beams at PSI are regularly used by manufacturers. A typical AA-type nickel-metal hydride battery (NiMH) is a compact wonder of science you can carry around in your pocket. Inside the battery, two metal strips sep- arated by an insulating foil are rolled up and placed into the metal can. The can is filled with an electrically conduct- ing liquid and sealed with a cap. The positive terminal is made from a nickel compound and the negative ter- minal is made from a substance known as a metal hydride. As the battery is charged, chemical reactions cause hydrogen to be re- leased from the nickel compound and be soaked up into the metal hydride. Scientists preparing a neutron When the battery is used, the chemical scattering experiment for research reactions reverse and an electrical cur- on new materials for batteries. rent flows out. 6 tion to meet efficiency and emissions made the surprising discovery that only gruelling conditions is crucial for im- targets and increase the driving range the first three out of eight discs were proving energy efficiency and guaran- of their machines. The oil pump is one being coated with oil. This did not teeing long-term reliability. of the biggest consumers of power from change with engine running speed or the engine. One of its main tasks is to how fast oil was pumped in. Conditions inside gas turbines are ex- lubricate and cool the bike’s clutch. Equipped with such precise informa- treme. Turbine blades can be rotating at The clutch transfers power and motion tion, the internal design of oil flow 3600 revolutions per minute, with hot from the engine to the wheels. The channels in the clutch can be adapted gases at 1400°C flowing through and most common design uses a row of to achieve good lubrication and cooling raising blade temperatures to 1000°C. plates and friction discs that are nor- using reduced oil flows. Engineers must have confidence that mally clamped together, but can be the blades can withstand the extreme pulled apart to change gear. http://psi.ch/zMpn conditions found inside the turbines. Neutron imaging can be used to see Blade materials are only chosen after right through the metal casing and map comprehensive testing of their behav- out where oil is flowing inside the iour to determine how they will per- clutch while it is running at speeds up form. Ongoing improvements to turbine to 8000 revolutions per minute. Stress-testing turbine blades blade materials and design continue In one new clutch design, the aim was to push up efficiency in fuel use and to reduce oil flow through the clutch to Turbines in power stations around the energy conversion. reduce the power consumed by the oil world convert the energy of fast-flow- By placing turbine blades and other pump. Oil is supplied through a hole in ing hot gases into mechanical motion parts in a beam of neutrons, engineers the drive shaft that then runs through to generate electricity. With tempera- can perform in-situ measurements con- the clutch and spreads out onto the tures reaching up to 90% of the melt- necting material behaviour under ap- eight spinning discs of the clutch. ing point of the turbine blades, ongo- plied loads to the microscopic fine Taking neutron snapshots lasting just ing research and development into the structure of the component. In-built 50 millionths of a second, engineers performance of materials under such residual stresses coming from the man- ufacturing process can also be meas- ured. Residual stresses are a significant problem in a component since they can lead to cracks and unpredictable changes in material properties. PSI is a world leader in in-situ engineer- ing stress measurements using neutron beams, attracting visitors from interna- tional engineering companies on a regular basis. In one recent project studying turbine blades, changes in the microstructure of a new design of turbine blade were traced to the casting process used to make the blade. Information from the experiments can be used to optimise the manufacturing procedure and mod- ify the aerofoil design to deliver the best performance and longest operat- ing lifetime. http://psi.ch/H11N 7 Earth and environment Many lessons can be learnt from plants surprisingly, boron can still be ab- and animals on how to solve common sorbed by the leaf into the dead problems and gain a deeper under- patches.