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 8 Earth and environment 21 Developing new technologies 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 Neutron Source SINQ 26 Accelerating protons 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.
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.
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. By doing this, the poplar can standing of our place on Earth. protect healthy areas of the tree and stop them from being overloaded with boron. In this way, poplar can store 20 times more boron than can be tolerated Cleaning soil with poplar by other plants. trees Planting poplar trees alongside crops in areas with poor water and soil offers Boron is one of the lightest chemical a way to protect food production. Har- elements found on earth and at low vesting trees from contaminated sites levels is an essential nutrient in plants. stops boron from going back into the But if soil has too much boron, food soil. Their timber then can be used for crops can fail. Experiments with neu- construction or fuel. trons have found that poplar trees can collect 20 times more boron than other plants and can be an effective way to Water in clays keep boron at the right levels in agri- cultural areas. Clay is often used to line rubbish pits and reservoirs as it is very good at In Turkey, waste water with high levels stopping water and other liquids from of boron pumped into rivers from power passing through into the surrounding plants has reduced citrus tree crop soil. New research linking the micro- yields. In California, the arid environ- scopic clay structure with how water Living plants are not damaged ment and weathering of rocks along travels through the clay is being used by neutron beams allowing coastal ranges has led to boron accu- in designs of long term stores for radio three-dimensional images of the plant, roots and soil to be mulation in the soil and groundwater active waste. made while it is growing. and interrupted sustainable agriculture. With neutron beams, plants can be Around the world, there is a growing easily tested for their boron hardiness. consensus that deep stores in rock are For one study, researchers studied the the most appropriate way to manage uptake of boron in poplar trees, willow radioactive waste. In countries such as Clay has a complex structure with layers trees, leaf mustard and lupin. Of the Belgium, France and Switzerland, deep of small plate-shaped particles sepa- four, poplar was the most tolerant of clay formations are being considered. rated by a network of thin water layers boron and willow the least. This was a Sweden and Finland, countries which and pores of varying sizes. surprise as poplars and willows belong do not have deep clay formations, fa- By combining neutron experiments to the same family. vour hard rock formations lined with with measurements of fluid draining Within the poplar leaves, boron was clay-based materials. Precise knowl- rates through the clay, the “twistiness” found to build up at the edges and tips. edge of clay properties is essential for of the pore network can be measured At high boron levels, the green colour- assessing the performance and safety and the local motion of water as it ing at the edges and tips fades and of these various radioactive waste dis- squeezes through the clay can be fol- patches of the leaf start dying. But posal designs. lowed.
8 Watching plants grow image of the plant roots to be made while it is growing. It’s normally quite difficult to see what Around the plant roots, experiments Clays that might be suitable include is happening underneath a plant with- find that the soil is modified and holds non-swelling clay kaolin (china clay), out pulling it out of the ground. By much more water than the soil further often used for porcelain and pottery, shining a beam of neutrons through away. The plants can create an emer- and a form of bentonite (montmoril- the roots of plants while they are grow- gency water supply for short periods of lonite based clay), which swells in wa- ing, the location of water in the soil drought. Measurements like this can ter. Betonite was found to be most ef- around the root system can be seen. also play a part in breeding plants for ficient at slowing water mobility. better survival in dry regions. This new microscopic knowledge can Because neutron beams are a very del- be used in computer simulations to icate measuring tool, living plants http://psi.ch/ytYf estimate the water flow in potential aren’t damaged when illuminated by a disposal sites. beam of neutrons. This allows a full 3D
9 Food, health and medicine
Good food, good health and good med- outer surfaces of the bubbles trapping binding on and breaking the droplet icine are key ingredients for a happy a thin watery layer between them and into smaller ones until they are the right and healthy life. Neutron scattering giving firmness to the food. size for absorbing into the body. experiments are making unique con- Studying the stability and structure of Eating too much fat can lead to obesity tributions to all three. the air bubbles over time is a challeng- and related diet issues. Scientists at ing task, and is not yet widely attemp PSI simulate the acidic conditions ted. But with the neutron scattering found in the stomach and use neutrons techniques at PSI, unique information to check changes to the structure of fat Secret life of bubbles within the molecular structure can be droplets at the molecular level. Fat easily recorded. droplets with a celluse-like coating Dairy products like ice cream, mousse Manufacturers now have a new way to and whipped cream must look fabulous learn how to make the right blend of and taste delicious days after they are ingredients before scaling up for their brought home from the shop. A micro- production lines. scopic look with neutrons could be a new way for food manufacturers to quickly find the best mix of ingredients A recipe for healthy eating for the most delicious results. When it comes to healthy eating, fat Despite only having a few ingredients, has always been something to be dairy foods like ice cream, whipped or avoided at all costs. But not all fat is sprayed cream, mousse and yoghurt bad. Studies at PSI investigate how have a surprisingly complicated chem- fats are digested in order to create istry. low-calorie recipes for greater personal The basic ingredients are usually water well-being. (or ice crystals), milk fat to add richness and stabilise the base mix, and sugars In the right amount, fat is a key part of to add sweetness and improve texture a healthy balanced diet. It provides and body. essential fatty acids which our bodies The cheapest ingredient in these prod- can’t make themselves, helps us to ucts is invisible: air. Tiny air cells whip absorb vitamins, and generally plays a ped into the base mix are largely re- part in maintaining healthy tissue, skin sponsible for the general consistency and immune function. and greatly affect the texture and vol- Fat also adds flavour and texture to ume. food: creamy-smooth cheese and but- Emulsifiers are added to bind the in- ter, tender moist cakes, and crispy gredients together and hold the air crunchy baked dishes. bubbles in place. A common emulsifier Digestion breaks down large food mol- Seeing the molecular structure of is egg, although others such as mono- ecules into smaller ones, releasing foams, food ingredients and glycerides and diglycerides are also in energy and making it easier for food to medicines is straightforward with common use. be absorbed into the body. neutron beams. To hold the bubbles in place, the emul- Acids in the stomach recognise the sifier molecules coat the inner and surface structure of fat droplets in food,
10 from plants have been found to resist Proteins are large biological molecules The ball-shaped artificial molecules are acid breakdown and are not absorbed that perform a wide range of jobs inside designed to uncurl in particular condi- into the body. Disguising fat from the the body. They help chemical reactions tions. The goal is to use these molecules body like this offers a new way to lower to work, copy DNA, and transport mol- to hold medicines and then release the intake of fat and make great-tast- ecules from one location to another. them in a particular place. ing, healthy and nourishing recipes. Whilst proteins are considered large on One test successfully completed has a biological scale, the objects are actu- looked at the release of vitamin B9 ally very small – thousands of them (folic acid) over a few hours for a po- Copying nature for medicine could fit across a piece of dust. The tential skin treatment for skin damaged shape of proteins is important for doing by sunlight. Learning from nature, researchers have particular tasks and for them to be The artificial molecules could also be developed tiny artificial particles that recognised in the body. attached to the surface of a silicon chip behave like proteins. They could be Inspired by natural proteins, a team of to make a very precise biological sen- used to release medicines very accu- researchers have found a simple and sor for hospital laboratories to test for rately in the body or make biological efficient way to make tiny artificial -mol the presence of particular molecules sensors. ecules. Experiments at PSI confirm that linked to a medical condition. they behave in a similar way to proteins.
11 Inside the Swiss Spallation Neutron Source SINQ
12 13 Heritage and culture
Valuable objects can be easily exam- western Switzerland. A deeply curved ined with neutron beams. They don’t cutting edge shows that it probably cause any damage and can see deep served as a weapon or a status symbol into the interior. They are the perfect rather than as a tool for felling timber tool for looking at rare Bronze Age axes or for woodworking. The axe has been or examining corrosion in sculptures dated to the Early Bronze Age A2a pe- and carvings. riod, around 1800 BC, and would prob- ably have been attached to a long wooden haft. Neutron beams are the perfect way to Making a Bronze Age axe understand how such a unique object was made, since they cause no damage Studies of a rare Bronze Age axe found and can give a clear view into metals. nearly 200 years ago near Lake Thun By rotating the axe in the neutron beam have shown that Bronze Age Central it can be deduced how the axe was Europe was heavily influenced by cul- manufactured. The structure has many tures in the Balkans and Caucasus. voids inside suggesting the axe mould was made from clay and residual water In the Buchholz quarter of Thun in 1829, turned to bubbles of steam in the gravel diggers uncovered one of the molten bronze. Because the voids are finest hoards of Early Bronze Age treas- still well-rounded and not elliptical, it ure in Northern Europe. On the south is very unlikely that the bronze surface side of Renzenbühl hill, looking out saw much forging after the axe was cast. over Lake Thun, the treasure was found The golden inlays were cut from a round in a stone cist burial of an important rod and hammered into recesses person. Twelve objects were found punched into the copper strips, which along with human remains, and the were themselves hammered into the burial is one of several making up a grooves cast into the axe. In a final small cemetery in the area. stage, the resulting uneven surface was One of the most impressive objects in smoothed out by grinding and polishing. the hoard was an axe inlaid with striking This study has given a new understand- decoration: 198 diamond-shaped gold ing of Bronze Age manufacturing tech- inlays in two parallel rows running along niques. It shows considerable influ- the front and back faces. The golden ence on Bronze Age Central Europe by inlays are set within two broad, copper cultures located in the Balkan Penin- metal strips, which are themselves set sula and the Caucasus region and into pre-cut grooves on both faces of rather less influence from Mediterra- the axe. The inlays are a rare decorative nean cultures as was previously technique for the Early Bronze Age and thought. are present on only seven bronze arte- facts found north of the Alps. http://psi.ch/UbCx The spoon-like “Löffelbeil” design of the axe is typical of those found in
14 single inlay at the flange
Predicting salt damage to buildings
Limestone, commonly used for building facades and sculptures, can be dam- aged by salty water soaking through refilled the porous stone. sample hole
Buildings and sculptures can be easily damaged by salts soaking into porous stone. Salts can come from many sources including road de-icing, flood- ing, or cattle, bats and pigeons living in the buildings. Salts dissolved in water seep through pores and cracks in the stone and form crystals as the stone dries out. The crystals can cause high stresses inside the stone leading to chipping and cracking. A new computer program now allows civil engineers to test ideas for repairs, conservation techniques or new build- ing materials without having to perform long-term studies over many years. 1 cm Neutron radiography can easily identify the transport of water and salt solu- tions through the stone as well as the location of salt crystals and cracks. Left: Bronze axe from the collection of the Results from wetting and drying exper- Bernisches Historisches Museum. iments on Savonnières limestone were used to test the program. A key finding Right: Images of the inside of the bronze axe generated with the technique of neutron was that major damage occurs during tomography. Depicted are virtual cuts through rewetting of the stone. the axe. The dark spots are air bubbles and The developers of the software antici- the light spots are gold adorments. pate it being widely used across Europe to reduce the life-cycle cost of buildings and extend the lifetime of building materials and structures.
15 Electronics and technology
Modern technology completely de- tic-like materials conduct electricity, 1s and 0s are stored on the disks in pends on electronics to function and emit light and can be easily shaped as small magnetic grains that have their magnetism for storing data. As elec- well as having all the properties of north or south poles pointing out of the tronic component sizes continue to traditional semiconductors like silicon. surface of the disk. A tiny write head shrink and information volumes rapidly Muons carefully implanted into a spin- flies over the surface flipping the poles expand, new ways of combining elec- tronic device are able to sense the local over as it stores information. tronics and magnetism are being environment and measure the spin How the poles of the grains flip direction found. direction of electrons passing through. in a magnetic field can be elegantly and Using this technique, it has been pos- sible to develop a device that can pre- cisely control the orientation of elec- Spintronics tron spins passing in and out of a material. Spintronics is widely predicted to The results are particularly exciting as change the way information is stored they show that many new devices can and transmitted in electronics and be built to have specific functions computers. Spintronic devices are ex- such as computer processor elements, pected to have smaller sizes and con- sensors, new types of computer mem- sume less power than existing elec- ory and intelligent light emitting dis- tronics. Building components to plays. control and exploit ‘spin’, a basic phys- ical property of electrons, is in its in- fancy, but neutron and muon beams at Measuring grains of PSI are perfect tools to use in their magnetism development. Data storage is big business and con- For over 100 years, electrons have been tinues to grow. One hard drive manu- flowing along wires in all sorts of elec- facturer recently announced it had trical circuits and devices. Electrons shipped 2 billion hard drives, noting can be pushed around by electric and that it took 29 years to sell a billion magnetic fields interacting with their drives and then only four more years charge, a natural property they have to sell another billion. Manufacturers along with mass. A third natural prop- are constantly searching for ways to erty is called ‘spin’ which gives the increase the amount of information electron its very own microscopic mag- that can be stored with their products. netic field. Controlling the orientation of spin in Magnetic recording technology is at the electronic circuits and using it to store heart of modern computer technology. and transmit information requires very Photos, music and video can all be delicate control of the material design. broken down and stored as patterns of New types of material known as organic 1s and 0s on small spinning disks that semiconductors are well-suited for can now easily store 1 terabyte (1TB) of spintronic applications. These plas- information.
16 uniquely studied with neutron scattering. To pack in so much information, differ- Molecular sandwiches Magnetic grains are typically made ent magnetic materials such as from a cobalt-chromium-platinum alloy iron-platinum alloys will need to be Building molecular sandwiches with separated by a thin shell of silicon used along with larger magnetic fields layers just a few atoms thick can create oxide. The average grain diameter is to flip the poles of the grains. structures with entirely new electrical typically around 8 nanometres, about Hard disk manufacturers are using re- and magnetic properties. Experiments a million times smaller than a grain of sults from neutron scattering experi- are the only way to learn about what sand. The grains are designed to make ments to develop the materials needed happens. sure that the magnetic particles can’t for these future disk designs. just flip from north to south at any time. Laying together different compounds Only when the write head passes over only a few atoms thick, opens up many can they change direction. possibilities for new discoveries. At the Hard disks will soon be able to store 10 boundaries between the layers, strange terabytes of data on one disk, and 60 things can happen. Insulators can be- terabyte hard drives are being forecast. come conducting or even supercon- ducting, where current flows without Electronics and data storage rely on generating any heat. Compounds that the interplay of electricity and magnetism in tiny components. Neu- are usually non-magnetic can become tron scattering experiments can magnetic. watch changes in the components. Laying down a thin layer of a manga- nese-containing oxide onto an alumin- ium-containing oxide causes an exter- nal magnetic field to form at the boundary between the two compounds. Neutron beams are able to measure how the atomic structure and mag- netism varies through the layers and across the boundary, giving unique information that can’t be obtained in any other way. In this case it was found that for the atomic structures of the two layers to bind together, the manganese-contain- ing layer was stretched and squeezed out of shape compared to its usual form. As a consequence, very large strains built up inside the new struc- ture. Moving away from the boundary be- tween the two layers, the strain in the structures becomes less and the mag- netic field is smaller in size, indicating that the strength of the magnetism is tightly connected to the atomic strain in the structure. This is a novel route for controlling magnetism in devices engineered from thin layers and it opens up new ways to develop electronics.
17 Discovering materials
Studies with neutrons and muons can map out precise information on magnetic structures inside materials that help to optimise them for future applications.
New technology and advances in sci- Microgels their surroundings by changing size, ence can only come after thousands collapsing to a compact form when and thousands of experiments testing Microgels are small soft particles with squashed, and then expanding back to out new compounds and learning a compact core and a fuzzy surface their original size when released. about their properties. The tough in- suspended in a liquid. Extremely soft When packed very close together, the tellectual challenges found at the fore- and flexible, they carry much potential fuzzy surfaces of microgels can overlap front of knowledge are a great test of for various applications. and merge together producing many a scientist’s skills. different and unusual physical proper- Microgels are soft particles made from ties. long polymer molecules loosely linked Neutron experiments at PSI are explor- together to form a net. They react to ing the internal structure and physical
18 properties of microgels in suspension. inert and harmless in the human body. gen or liquid helium, and can carry One finding is that pressure is a more They are ideal for transporting medi- more than 100 times the current of a precise way to control microgel size cines. copper cable of the same size. They are than temperature. Increasing the pres- Neutron scattering experiments allow used inside hospital MRI scanners, as sure squeezes the liquid out of the developers of new materials to under- electronic filters in mobile phone base microgels, and they become more like stand how the active molecules interact stations, in the industrial separation compact individual particles rather with the host material. of iron impurities from kaolin clay to than merging into each other. In one example, researchers were able improve its purity and whiteness, and Microgels are steadily being used in to identify individual molecules inside in some power grids to transfer large more and more applications including the aerogel and confirm that nearly amounts of power between nearby in- water purification, making artificial 80% of the pores were filled. They stallations. muscles, and as tiny switches and showed that each pore held a single The simplest superconducting materi- valves. molecule, and that the molecules had als are well-understood, but more and kept their usual shape and response more superconductors are being dis- when illuminated with light. covered with properties that defy ex- Making smart materials planation. Neutron scattering experiments at PSI Smart materials that react to their nat- Understanding have recently discovered that a ceri- ural environment can be designed by superconductors um-cobalt-indium material placed in a embedding molecules activated by very strong magnetic field creates a light or temperature into a passive One of the great scientific discoveries new type of superconductivity coupled supporting material. One of the first of the 20th century, the incredible with well-ordered magnetic field orien- development stages is to check if the property of superconductors to let tations of the ions in the material. active molecules can still function in- electricity flow without resistance at This is surprising, as superconductivity side their new home. low temperatures is steadily being and magnetic fields are normally seen harnessed. Neutron scattering and as rivals with very strong magnetic Embedding active molecules into a muon spectroscopy experiments at PSI fields destroying the superconducting neutral host framework is of interest to are at the forefront of the worldwide state. many areas of science. In medicine, intellectual effort to explain how they By constantly pushing at the frontiers drug molecules could be released actually work. of knowledge, PSI scientists are pursu- slowly from implants. In optical appli- ing breakthroughs that could lead to cations, light sensitive materials could Superconductivity was discovered in computers working at speeds beyond be used as switches in electronics or 1911 and occurs in many ordinary met- the limits of silicon technology, or laser devices to block or amplify light als such as lead and aluminium at very transform the performance of clean of a particular colour. low temperatures about 290 degrees energy generation and distribution. Aerogels are one of the most popular below room temperature. Electric cur- materials to host active molecules. rent can freely flow in a superconduct- http://psi.ch/AhBt Discovered in 1931, aerogels are the ing wire without causing it to heat up. world’s lightest solid materials with In contrast, the electrical resistance of around 99% of the volume made from a normal copper wire can cause it to a network of tiny air bubbles. Silica heat up, glow brightly and even melt. aerogels made from sand are the most Superconductors are typically cooled commonly used as they are chemically to low temperatures using liquid nitro-
19 Engaging with industry
PSI actively encourages industry to iour of materials already in use, com- Varta and Toyota are making use of make use of its research facilities ei- panies from Switzerland and across neutrons and muons to refine their ther directly or in partnership with Europe frequently join forces with uni- understanding of materials found in university research teams. versity research teams to combine commercial NiMH and lithium-ion bat- their knowledge and expertise with teries. that of PSI. Scientists from Hitachi are now able to measure the tiny grains that store data Universities, industry Research projects can range from long on hard disks and what is taking place and PSI term refinement of procedures for later physically within each grain. use in product development, through Hydrogen storage materials are a popular When it comes to developing new to building a systematic understanding area for researchers. Out of all the ele- materials or understanding the behav- of new materials. ments in the periodic table, hydrogen is
SwissNeutronics is a company founded on expertise developed at PSI. Today it supplies components all over the world. Instruments at SINQ are used by the company for 20 testing and development. seen best by neutron beams. Nor- straightforward measurements to solve Spin-off company way-based SINTEF is the largest inde- immediate problems. pendent research organisation in Scan- SwissNeutronics was founded in 1999 dinavia with an interest in energy Schaeffler/LuK used neutron imaging as a PSI spin-off company to commer- conversion and end use. SINTEF research- to identify real-time oil distributions in cialise and exploit knowledge in build- ers use neutrons to study the uptake of prototypes for multi-disc clutches and ing optical components for neutron hydrogen in materials that could find use with this knowledge optimise the de- instruments. for bulk storage of hydrogen. sign to reduce fuel consumption. The Nestlé Research Centre in Laus- Alstom make regular use of neutron The performance of neutron instru- anne makes regular use of the PSI neu- scattering to measure the inner stresses ments depends on the number of neu- tron facilities for evaluating the poten- of gas turbine blades made from new trons arriving at the instrument. This tial of different innovations that could alloys or treated in different ways after can be greatly boosted by installing be used in manufacturing processes. manufacture. special mirrors that efficiently guide Stihl are working with PSI to reduce neutrons over long distances from the emissions from 2-stroke chainsaw en- source to the instruments. Solving industry problems gines to comply with EU legislation. Whilst the Swiss Spallation Neutron Using neutrons, Stihl engineers have Source SINQ was being built, PSI sci- Industry users, in many cases, are keen been able to study the distribution of entists and engineers built up a deep to use neutron or muon beams for fuel and lubricants in an engine run- understanding of how to make high ning at 3000 revolutions per minute quality coatings for neutron supermir- and understand what changes can be rors. made. Today, SwissNeutronics supplies neu- tron optical components to customers http://psi.ch/zMpn around the world and is considered one of the leading companies in this sector.
A future neutron source Developing new technologies for Europe
Building new instruments for frontier Swiss scientists and engineers are research at a large research centre using their expertise to help build new requires careful development and European science facilities to meet planning to maximise performance and future research needs. meet exacting scientific requirements. The European Spallation Source is a Scientists and engineers at the Swiss new research centre to be built in Lund Muon Source SμS have been working in Sweden. A partnership of 17 coun- for many years in partnership with com- tries including Switzerland, it is panies including Dubna Detectors, planned to start operating in 2019. Photonique SA, Hamamatsu Photonics, Based on technology very similar to the and Zecotek to develop compact and Swiss Spallation Neutron Source SINQ, efficient modern muon detectors. The staff at PSI are playing a key role in new detectors can work in very high developing and testing components for magnetic fields and be packed closely the new centre, as well as designing together. They are now installed on research instruments together with several of the muon instruments at PSI, partner organisations in Denmark. opening up new areas of research. The technology will be shared with other muon laboratories around the world.
Inside the Swiss Muon Source SμS
23 Using neutrons and muons
Different experimental set-ups are chosen for different experiments because each can give certain types of information. Scientists choose the best instrument for the job. Instruments can be adjusted and adapted to match what is being studied in the experiments.
24 Everything is made of atoms and atoms tured by detectors, or cameras, placed are tiny. A million of them could fit around the object allowing the loca- across a piece of dust. At PSI, research- tions and movements of the atoms to ers use beams of neutrons and muons be worked out. to find out where atoms are and what Alternatively neutron pictures can be they are doing. made. PSI is the world-leader in exploit- ing this ‘neutron-imaging’ approach to experiments.
What is a neutron? http://psi.ch/GH6K
Neutrons are everywhere. Along with protons and electrons, they make up atoms, the basic building blocks of the What is a muon? natural world. Neutrons are tightly bound together with protons in the They might sound exotic but hundreds nucleus at the centre of the atom. Set of muons are raining down on each of free from the atom, neutrons are a us every second. Formed by cosmic valuable tool for materials research. rays hitting the atmosphere, these elementary particles can also be cre- At the Swiss Spallation Neutron Source ated by particle accelerators and used SINQ, beams of neutrons are made and for materials research. used to illuminate samples to discover their microscopic properties. At the Swiss Muon Source SμS, beams Neutrons have unique features that of muons are made and used to illumi- make them very valuable for research. nate samples to discover their micro- They are just the right size to accurately scopic properties. measure the distances between atoms Muons are charged particles that can in a material, and they can sense how also behave like a small compass mag- the atoms are moving and measure the net. strength of the forces holding them When an object is placed in a muon together. beam, the muons are implanted at They also have no electrical charge, various depths. Electric charges from allowing them to see deep into the the atoms inside the material cause interior of thick objects and not just muons to stop in the gaps between look at the surface. Their gentle inter- atoms. action is perfect for examining delicate, Muons are very sensitive to their local valuable or rare materials. environment and can feel weak mag- They also behave like a tiny compass netic fields or atomic motion. They spin magnet, making them ideal for explor- around at a speed that reflects what ing magnetism at a microscopic scale. surrounds them. In fact, the majority of what is known By measuring this speed researchers about microscopic magnetism has obtain knowledge of the properties of been learnt through experiments with surrounding magnetic fields or chemi- beams of neutrons. cal environments. When an object is placed in a neutron beam, the beam passes through and http://psi.ch/rn6D is scattered by the atoms inside the object. The scattered neutrons are cap-
25 Making neutrons and muons
Making particle beams requires enor- Making neutrons mous machines blending science with engineering. The Swiss Spallation Neu- Neutrons are released when the proton tron Source SINQ and Swiss Muon beam is fired into a target of lead in the Source SμS are found inside three neutron target hall. For each proton that huge buildings on the PSI west site. strikes, 10 neutrons are released.
A walk inside the huge buildings of the The proton beam comes up through the neutron and muon sources is a rare floor and strikes the lead target which chance to enter a world that at first is housed in the middle of the huge appears chaotic. A maze of walkways structure in the centre of the hall. The and walls, cables and cranes, strange cylinder-shaped target is 50 cm long and fabulous equipment at every turn, and 15 cm wide. It is cooled by water to particle beams traveling along chan- stop it melting when the proton beam nels in all directions. But after a little hits it. time, the strict logic and order soon Neutrons are guided to the different begins to appear. instruments in the neutron target hall and neutron guide hall inside tubes coated with special mirrors that guide Accelerating protons neutrons. There are 18 instruments operating at the Neutron and muon beams are created Swiss Spallation Neutron Source SINQ. at PSI by firing a continuous stream of protons traveling at 80% light-speed http://psi.ch/X135 into a sequence of targets made of lead or carbon. Making muons Protons are sent to the targets by the high intensity proton accelerator. The Muons are created when the proton protons are made by splitting apart beam passes through two carbon tar- molecules of hydrogen gas. gets in the experimental hall. The accelerator, neutron and muon sources work continuously through the The muons are guided away from the day and night for more than 220 days targets by electric and magnetic fields a year. and then directed to the different muon The proton accelerator at PSI delivers instruments. the most powerful proton beam in the There are 6 instruments operating at world. the Swiss Muon Source SμS. http://psi.ch/tYQ2 http://psi.ch/HKxX
26 Inside the SINQ neutron target hall. Neutrons are released in the middle of the large blue structure and travel to instruments sur- rounding it.
27 Electronics engineer Building hardware to process detector signals We make it work
A large team of people with many different skills keep the PSI facilities working day and night. Meet a few of them:
Radiation protection technician Plumber Ensuring a safe working environment Perfecting pipework carrying cooling for all water and compressed air Crane driver Skillfully moving tonnes of equipment around every day Electrician Installing low voltage cables for con- trol systems, signal and data transfer
Software developer Writing code to squeeze the most out of data
Multi-skilled mechanic Creating precision components for unique scientific equipment
Cleaner Cleaning carefully around delicate and expensive equipment
28 Technician Maintaining equipment to keep things colder than outer space Vacuum engineer Making air-free paths for particle beams
Accelerator physicist Delivering high quality particle beams for experiments
Computer networker Keeping computers and equipment happily communicating
Design engineer Turning instrument ideas into reality Electronics engineer Making cameras and detection systems fast to capture new science
Scientist Designing experiments to make new discoveries
29 Bird’s eye view of the Paul Scherrer Institute.
30 PSI in brief
The Paul Scherrer Institute PSI is a research institute for natural and engineering sciences, conducting cutting-edge research in the fields of matter and materials, energy and the environment and human health. By performing fundamental and applied research, we work on sustainable solu- tions for major challenges facing society, science and economy. PSI develops, constructs and operates complex large research facilities. Every year more than 2500 guest scientists from Switzerland and around the world come to us. Just like PSI’s own researchers, they use our unique facilities to carry out experiments that are not possible anywhere else. PSI is committed to the training of future generations. Therefore about one quarter of our staff are post-docs, post-graduates or apprentices. Altogether PSI employs 2100 people, thus being the largest research institute in Switzerland.
Head of Research Division Research with Neutrons and Muons Prof. Dr. Christian Rüegg Imprint Tel. +41 56 310 47 78 [email protected] Concept/Text Dr. Martyn J. Bull Head of the Neutron Scattering and Imaging Laboratory Editing committee Prof. Dr. Michel Kenzelmann Dagmar Baroke, Dr. Martyn J. Bull, Tel. +41 56 310 53 81 Dr. Paul Piwnicki [email protected] Photography and Graphics Head of the Muon Spin Spectroscopy All Photos Scanderbeg Sauer Laboratory Photography except: Dr. Alex Amato page 1, 30: Markus Fischer Tel. +41 56 310 32 32 page 6: Frank Reiser [email protected] page 15: Daniel Berger page 18: graphic by H. M. Rønnow Head of the Scientific Developments and Novel Materials Laboratory Design and Layout Dr. Marc Janoschek Monika Blétry Tel. +41 56 310 49 87 Printing [email protected] Paul Scherrer Institut Head of PSI User Office Available from Dr. Stefan Janssen Paul Scherrer Institut Tel. +41 56 310 28 75 Events and Marketing [email protected] Forschungsstrasse 111 Head Corporate Communications 5232 Villigen PSI, Switzerland Dagmar Baroke Tel. +41 56 310 21 11 Tel. +41 56 310 29 16 Villigen PSI, November 2018 [email protected] Paul Scherrer Institut :: 5232 Villigen PSI :: Switzerland :: Tel. +41 56 310 21 11 :: www.psi.ch