sign in sign up
<<
Home , B2FH paper, Nuclear astrophysics

NUCLEAR : COSMIC ORIGINS SCIENTISTS EXPLORE THE CREATION OF ALL THE ELEMENTS THAT WE FIND ON EARTH AND ACROSS THE UNIVERSE 2 INTRODUCTION , THE ORIGIN OF THE ELEMENTS AND US TRACING THE PATH FROM STARDUST TO PEOPLE

ll matter on Earth, including us, is composed of atoms, which in turn are made up of subatomic Aparticles. These include negatively charged electrons, which surround the extremely dense – itself composed of further particles: positively charged and neutral . The number of constituent protons in a nucleus defines the basic properties of each of the familiar elements, such as , oxygen, carbon or . Atoms can then combine with others through their electronic ‘glue’, forming chemical bonds to generate millions of kinds of molecules – from simple water (two atoms of hydrogen and one of oxygen) through to the complex DNA genetic code characterising individual humans.

Elements, especially those consisting of heavier atoms with large numbers of protons, may have “WHERE DO THE ELEMENTS COME many ‘’, each with differing numbers of FROM, HOW WERE THEY MADE AND neutrons. This latter figure defines the particular isotopes of an element that can exist. The various WHY IS THERE SO MUCH MORE OF combinations of protons and neutrons possible ONE ELEMENT THAN ANOTHER? THE could, in fact, generate up to 10,000 different ANSWERS ARE BOTH EXOTIC AND kinds of nuclei. Yet everyday stable matter is MYSTERIOUS – AND LIE IN built from only about 300 nuclear species. These THE STARS.” include 83 elements and their isotopes, which are found on Earth. WHY DOES THE SHINE?

The Sun is an ordinary middle-aged , one of 100 billion in our Galaxy alone. As such, it consists largely of hydrogen (a nucleus made of one ) and (two protons, two neutrons). These, the lightest elements, are thought to have been made in primordial processes just after the , nearly 14 billion years ago, and then condensed through gravity into massive incandescent balls of gas – the first stars. In stars, the tremendous pressure and drive the fusion of hydrogen nuclei into more helium, as well as carbon, oxygen, and other nuclei, with the release of huge amounts of energy. We see the manifestation of this process as the sunshine and warmth that sustains life, but also in the variety of elements around us – the oxygen we breathe, the carbon that is the basis of life and that we use as fuel. 3 WHAT IS AND WHY DO WE NEED TO KNOW ABOUT IT?

Nuclear astrophysics is the Nuclear astrophysicists study of the nuclear reactions pursue their research in that fuel the Sun and other several ways: stars across the Universe, and •• by detecting and analysing of how they create the variety emissions from stars, of atomic nuclei. Almost all the dusty remnants from the elements found on Earth – exploded stars and from except the very lightest ones – compact ‘dead’ stars. were exclusively made in stars. •• by designing laboratory Understanding the underlying experiments that explore astrophysical processes gives stellar nuclear reactions in us clues about: the Big Bang, in stars and in •• the origin of the elements explosions. and their abundances; •• by analysing geological •• the origin of the Earth and its samples and those from composition; extraterrestrial sources such •• the of life; as meteorites and the grains •• the evolution of stars, of ‘stardust’ they contain. galaxies and the •• by carrying out theoretical Universe itself; calculations on nuclear •• the fundamental laws and behaviour and its interplay building blocks of Nature. with the stellar environment. During their lives, stars There have been many generate many exotic, short- research successes in recent lived nuclei that do not exist years but there are still on Earth, but are nevertheless many mysteries to solve. significant in understanding The European astrophysics the structure of all nuclear community is playing a species and the fundamental key part in taking this forces governing them. In turn, work forward. This booklet this knowledge is essential highlights the achievements, When the fusion fuel in their cores runs out, to developing, for example, challenges and applications of stars like our Sun eventually blow off their outer new types of safe energy this exciting multi-disciplinary envelopes and their cores end up as quiescent and isotopes of industrial or scientific area. ‘white dwarfs’. However, stars that are much medical use. more massive collapse under their own gravity and then explode as a supernova, throwing Water, which is composed of hydrogen and oxygen, is the key to life on Earth. Hydrogen was made in the Big Bang, while oxygen was out material far into space. During this violent synthesised in stars via nuclear reactions event, ultrafast nuclear processes between transient exotic nuclei to the synthesis of many of the important elements that shape our life (‘’). Such supernovae make the calcium in our bones, iron in our blood, silicon in the sand on our beaches, and rare and precious gold and platinum. Eventually, the material dispersed by this catastrophic death of a star condenses into new stars, perhaps with accompanying planets that could support life. We are, indeed, the children of stardust! Nuclear astrophysicists investigate the processes underlying the creation of the elements and their influence on broader cosmic structures and their evolution, as the next pages will show. 4 ACHIEVEMENTS 1 THE CREATION OF THE ELEMENTS AND THEIR ROLE IN THE UNIVERSE

OVER THE PAST CENTURY, WE HAVE BUILT UP A COMPREHENSIVE PICTURE OF WHAT STARS ARE, OF THEIR DIVERSE LIFE-CYCLES, AND HOW NUCLEOSYNTHESIS IN STARS HAS SHAPED THE EVOLUTION OF THE UNIVERSE AND LED TO THE FORMATION OF PLANETARY SYSTEMS LIKE OURS

uring the 19th century, physicists had noted that the Sun’s spectrum contained WHAT WE Dsets of dark ‘absorption’ lines that were NOW KNOW also characteristically observed in the hot glow emitted from particular elements in the laboratory. •• The primordial elements, hydrogen and helium Spectroscopic studies showed that matter across were made in the Big Bang. the Cosmos was, indeed, made from the same •• Our Sun and all stars are natural nuclear elemental building blocks. From this revelation, fusion reactors that manufacture the following the huge scientific steps made in the chemical elements. early 20th century – in uncovering basic •• The processes in stars mediate the evolution of (quantum physics and Einstein’s Relativity the galaxies and thus the Universe. theories), and astrophysics (the Big Bang and the •• Stars are key players for the emergence of life. expansion of the Universe) – researchers began The intermediate-mass stars produce carbon; the long journey to unravel where and how all the massive stars and supernovae synthesise the elements in the Universe were created. oxygen we breathe, the calcium in our bones, and the iron in our blood.

FIRST IDEAS in the 1940s had advocated the idea that stars produce all the elements in the Universe. The hydrogen-fusion reactions that make the Sun and most of the stars shine had been worked out in detail by and Carl Friedrich von Weizsäcker in the late 1930s. But many scientists remained sceptical, because it was thought that stellar interiors never become hot enough for fusion reactions; and even if they did, it was not clear how the fusion products could get out of the stellar core. This stimulated and his student Ralph Alpher, in 1948, to evaluate in detail previous ideas on the synthesis of all elements in the hot, early Universe of the Big Bang. Later studies interiors by a variety of nuclear processes. concluded that only a handful of the lightest Most of these were defined and analysed in the nuclei (specifically, deuterium, helium-3 and seminal papers of Al Cameron, together with helium-4, and some -7) can be produced Margaret and , Willy Fowler in the early-universe environment, and all other and Fred Hoyle (above left to right) in 1957 (the elements are synthesised in stellar or supernova latter now referred to as the B2FH paper). 5

THE COMPLEX WEB OF CREATION

4 4 4He 4He He He Today, we understand cosmic hydrogen, helium nucleosynthesis as the result helium, nitrogen of a complex series of reaction helium, carbon, neon networks occurring at different 8 4 4 4 Be He -7 Lithium-7 4He 4He He He stages in a star’s life, and oxygen, carbon differing according to its overall oxygen, neon, magnesium 8 4 mass. For most of their lives, 12 silicon, sulphur C Be He stars ‘burn’ hydrogen to helium, only if 10+ nickel, iron (inert core) 8 4 solar mass Be He Beryllium-7 Lithium-7 but as the hydrogen is used up, helium starts burning to A chart showing how the elements are built up in stars from the form carbon and oxygen. This lightest nuclei through paths involving different nuclear processes 8 4 12 12C Be He is what will happen in the Sun. C When all this fuel is used up, is unstable, the subsequent seconds, together with lots of it will shrink under gravity to transformation of a oxygen and other elements up form a dense core, and the heat into a proton with the emission to iron. We see this collapse as given off will cause the outer of an electron creates the a supernova – an object shining 12 C layers to swell creating a red next heaviest element. In this millions of times brighter than giant. Eventually, the outer gas process, called the s-process the Sun. Left behind is an ultra- layers puff off, leaving behind for ‘slow’, small amounts dense object – a The ‘burning’ of helium to carbon a dense remnant – a white of elements up to lead and or a black hole. via the ‘triple alpha’ process, dwarf consisting mostly of the bismuth are made. which is responsible for the products of helium burning – amount of carbon created in stars 162 and needed for life. It is an unlikely carbon and oxygen. reaction but is driven by subtle Much more massive stars coincidental energy relationships later burn carbon to build between carbon, helium and up heavier beryllium nuclei 184 elements such p-Process 126 as neon and Gamma-rays and neutrinos kick out silicon; finally, neutrons Lead the burning The build-up of 82 elements in a typical star s-Process ‘Slow process’ via chain of stable nuclei through

rp-Process Tin Other types of explosion can ‘Rapid proton process’ via unstable proton-rich nuclei 50 happen if a white dwarf is part through of a binary star system – and Many of the heavier elements most stars are. Re-ignition may are formed in a similar way, but occur from material drawn off Nickel 82 in the wake of a spectacular its companion. The accreted 28 explosion, which by some matter triggers a ‘’ r-Process unknown mechanism creates explosion and further nuclear ‘Rapid process’

Proton number Proton 20 50 via unstable a brief but intense flood of reactions. A very massive white neutron-rich nuclei through neuron capture neutrons. A series of neutron- dwarf can self-destruct in a capture reactions within just a so-called ‘thermonuclear’ or 8 28 few seconds would generate a ‘type-Ia’ supernova explosion. 20 2 Fusion up of silicon produces elements rapid (or r-) process, producing In these ways, newly-made 8 to iron up to nickel and iron. The also the rare, heaviest elements elements are spread across 2 fusion stages speed up over up to gold and plutonium. space, forming vast clouds Neutron number time – hydrogen burns over Such an explosion may of material called nebulae, millions of years or more, while happen when the nuclear fuel which eventually condense the last stages happen in a in a massive star runs out, into the next generation of matter of days. At the red-giant and the central core collapses stars and planets. With each stage, elements heavier than under gravity, which creates subsequent generation, more iron are built up by a process a gigantic shockwave that and more of the elements in which a nucleus captures rushes outwards. The neutron- heavier than hydrogen are a stray neutron to form a rich heavy elements may created in the Universe. heavier . If this isotope form in its wake in just a few 6 ACHIEVEMENTS 2 NUCLEAR ASTROPHYSICS NOW

THE FIELD OF NUCLEAR ASTROPHYSICS HAS EXPANDED TO BECOME A TRULY MULTI-DISCIPLINARY SUBJECT

heorists have developed and keep refining the models of nucleosynthesis reactions, and of stellar interiors and Tsupernova explosions, while observational astronomers scrutinise the abundances of elements and their isotopes across the galaxies, in stars and in the dispersed material between the stars and galaxies – all across cosmological evolution. Here on Earth, experimental nuclear physicists study the behaviour of the relevant nuclei in the laboratory.

CURRENT TOOLS OF NUCLEAR Part of the LUNA accelerator galaxies, stars and nebulae from radio through in the Gran Sasso underground ASTROPHYSICS RESEARCH laboratory; it is used to study visible wavelengths. To observe at the shorter ACCELERATOR EXPERIMENTS the nucleosynthesis of the wavelengths of ultraviolet/X-rays to gamma-rays, A key way to study nuclei and reactions of lightest elements instruments must be sent into space above the astrophysical significance is to re-create them absorbing atmosphere. Such satellite observatories in the laboratory. Nuclear physicists fire beams are able to map the distribution of isotopes in space, of subatomic particles or ions (atoms stripped and home in on active sites such as supernovae, of most of their electrons) at targets to create novae, neutron- star systems, and regions of intense new nuclei through nuclear reactions. The nuclei recent star-birth, where nucleosynthesis reactions are separated out into beams to study how they leave their observable traces. react. Mapping the secondary particles and gamma-rays provides clues to the structure and NEUTRINO DETECTORS stability of such rare and unstable nuclei. Small, Neutrinos are ghostly subatomic particles with specialised accelerator laboratories around hardly any mass, and are produced in profusion Europe, or dedicated units at large central in nuclear astrophysical processes. Because they

facilities, employ such beams of both stable and Neutron-induced nucleosynthesis hardly interact with materials, they are difficult to radioactive ions, as well as protons, neutrons is studied at the neutron time-of- detect, but also escape from deeply embedded and lasers. Experiments probing the very slow, flight facility at CERN in Geneva sites, such as the interior of infrequent reactions that make the lightest our Sun. Neutrino detectors are located deep elements are studied in underground laboratories underground (neutrinos can pass through the to avoid interference from cosmic rays. Earth while other particles cannot).

STARDUST IN THE LABORATORY COSMIC-RAY DETECTORS Meteorites contain tiny grains of stardust left Cosmic rays consist of subatomic particles and over from previous generations of stars. The nuclei, accelerated to energies much higher than isotopic composition of these ‘pre-solar’ grains ever attained in terrestrial particle accelerators. are analysed by cosmochemists using specialised They can reach us from distant supernovae, so are mass spectrometers to provide important also material messengers of nuclear processes in information about the nuclear history of their Isotope composition in meteorites the Universe. parent stars. We have even found Fe-60 nuclei can be analysed at the nanoscale using a type of mass spectrometer from a nearby supernova in a crust sample from COMPUTERS AND THEORY called a nanoSIMS the Pacific ocean floor. Theoretical studies of the conditions in stars and how they evolve, the nuclear reaction rates, COSMIC REACTIONS IN THE LABORATORY and how matter and energy is produced and Heavy-ion collisions and high-power lasers transported to the surface are used to compare can be used to simulate the hot, high-pressure with both astrophysical observations and laboratory conditions that exist inside stars at all stages of measurements. Supercomputers need to be their lives, and to study the nucleosynthesis employed to carry out three-dimensional simulations that occurs. of stellar interiors and their sometimes fast evolution – conditions not possible to reproduce in the ASTRONOMICAL TELESCOPES laboratory. Theories of and stability, The spectra of stars reveal the proportions based on quantum descriptions of the fundamental of elements present. Large, ground-based strong and weak nuclear forces holding nuclei observatories feature sophisticated spectrographs Two of the four units of ESO’s together, are essential to link stellar models to nuclei Very Large Telescope in Chile that can detect elements and their isotopes in born there. 7

MAKING THE LIGHTEST ELEMENTS Hydrogen-burning reactions leading to elements helium to have been measured in the LUNA accelerator project at the Underground Gran Sasso National Laboratory in Italy. Fundamental calculations can be compared with these, and teach us about nuclear reactions at the lowest energies, as are characteristic for stars.

STARS REVEAL THEIR SECRETS IN THE LABORATORY Neutron-capture rates associated with the s-process in giant stars are being measured by firing neutron beams at specific targets. Using databases of those reactions, results SOME ACHIEVEMENTS AND from the analyses of pre-solar grains can be interpreted. Such dust THEIR IMPLICATIONS grains can be found in meteorites and analysed in the laboratory. They have also revealed extreme OUR UNDERSTANDING OF THE UNIVERSE HAS isotopic ratios of elements such as carbon, EXPANDED GREATLY THROUGH THE STUDY OF oxygen and silicon that provide clues to the NUCLEAR ASTROPHYSICS nucleosynthesis processes that made them in giant stars and supernovae. BIG-BANG NUCLEOSYNTHESIS Measurements of the abundances of hydrogen SUPERNOVA EXPLOSIONS PROBED and helium in the Universe confirm the principles Supernova 1987A – the first such explosion to be of the Big Bang theory. close enough to us to study in detail – provided a test of theories of nucleosynthesis. Neutrino THE EVOLUTION OF THE UNIVERSE observatories detected 24 neutrinos, which Spectroscopic studies of the composition of was consistent with theoretical models of core stars of all generations, ages and sizes, across all collapse. Elements going from oxygen to calcium wavelengths of light, have provided a remarkable were detected early in ejecta through supernova description of the evolution of Universe and its spectroscopy, and after a few months, the heavier constituents. Rare but significant unstable nuclei, elements from deeper inside, nickel, cobalt and such as aluminium-26 and iron-60, have been iron, were identified. The X-rays and gamma-rays identified by gamma-ray observatories. These from their radioactive decays are proof of their isotopes act as probes of the details of stellar and The INTEGRAL gamma-ray synthesis in the supernova. Recently, the INTEGRAL galactic processes. space observatory gamma-ray observatory measured the of a more long-lived isotope titanium-44, HOW THE SUN WORKS also synthesised in the supernova interior. Measurements of neutrinos emitted in solar nuclear reactions seemed to indicate – rather THE MINIMUM AGE OF THE UNIVERSE alarmingly – that our model of how the Sun The Very Large Telescope of the European Southern works was wrong. Far fewer than expected Observatory has measured the tiny amounts of seemed to reach the Earth. This stimulated a new and thorium present in very ancient stars. development in particle-physics theory and our Using this radioactivity ‘clock’, the age of this star understanding of the fundamental laws of Nature, could be determined as 13.2 billion years. It most which showed that neutrinos could change likely was born from the remnants of a supernova their form. With this idea, improved neutrino from the first generation of supergiant stars that measurements confirmed the basics of the solar formed after the Big Bang, 13.8 billion years ago. model, and now new precision tests of nuclear neutrino fluxes are being done, also utilising The SNO in Canada, which confirmed the behaviour of seismic data to constrain the Sun’s interior. solar neutrinos 8 THE CHALLENGES

THE MYSTERIES TO UNCOVER

UNDERSTANDING NUCLEAR REACTIONS AND NUCLEI IN A WIDE RANGE OF COSMIC ENVIRONMENTS HAS FAR- REACHING IMPLICATIONS FOR OUR QUEST TO ANSWER THE BIG QUESTIONS: THE NATURE OF MATTER, THE EVOLUTION OF THE UNIVERSE AND OUR OWN ORIGINS

lthough we now have built up a basic description of nuclear Aastrophysical processes, there are many issues that are unresolved. Many nuclear reactions happen with very low ADVANCED STAGES OF NUCLEAR BURNING probability. The exotic nuclei thought to There is a huge dearth of information about the be significant in nucleosynthesis mostly reaction paths leading to the heavier elements. cannot be made in nuclear experiments. They require much better theoretical models of The reaction networks are extremely nuclear structure and stability, to be supported complicated and happen in extreme, by new experimental measurements using complex environments that are still poorly both stable and radioactive nuclear beams to understood, and are difficult or impossible investigate the complex variety of pertinent to reproduce on Earth. reactions and their outcomes.

OPEN ISSUES AND CHALLENGES WHAT DETERMINES THE FATE OF A STAR? LACK OF LITHIUM IN THE EARLY UNIVERSE We still do not understand the details of the The amount of lithium-7 observed in the oldest processes that determine whether a star becomes stars in the outer reaches of our Galaxy is far a red giant and then a white dwarf, or explodes less than predicted by calculations of Big- as a supernova leaving behind a neutron star or a Bang nucleosynthesis. Answers may be found black hole. Investigation of the underlying nuclear through better interpretation of spectroscopic and transport processes is vital here. observations, or by invoking the existence of exotic particles that could be constituents of so- HOW AND WHERE ARE THE HEAVIEST called dark matter, which is thought to make up ELEMENTS MADE? about 25 per cent of the Universe. Establishing We know that large numbers of neutrons need the precise mix and density of matter, whether to be present in a highly energetic environment dark or nuclear, in the primordial Universe is a to make the heaviest elements like gold and prerequisite for understanding its evolution. uranium. Supernovae interiors, and material falling onto neutron stars or black holes, seem likely candidates. The enormous number of rapid

neutron-capture and4 possibly4 neutrino-induced 4 4 He He He He reactions in these extreme environments needs theory combined with experimental studies constraining structures of the exotic nuclei involved. Complex interplay between the burning 8 4 Be He Beryllium-7 Lithium-7 shells of intermediate-mass stars also play an important role in heavy-element synthesis.

8 4 12 Be He C THE EARLY STAGES IN STARS A PHYSICAL MODEL FOR SUPERNOVAE Although synthesis of the light elements is We still have a poor understanding of how quite well understood, there are critical supernovae occur and what happens when the reactions, such as the fusion of carbon and ‘flames’ of explosive nuclear burning zip through helium to oxygen, that are hard to predict the entire object within a second or less. Precise 12C from theory and need better laboratory understanding of the flame shapes, wrinkles, and measurements. Recently, the amounts of carbon speeds in such exotic matter are key to a realistic and oxygen in the Sun were shown to be one- model. The neutrino ‘wind,’ as it comes off the third less than previously thought. Furthermore, resulting cooling neutron star and interacts so these abundances do not tally with results from weakly with surrounding matter, may be a key helio-seismology measurements. driver in the genesis of heavy elements. 9

HOW DO THE ELEMENTS BECOME DISPERSED ACROSS SPACE? We do not know exactly how stellar winds and supernova ejecta spread over entire galaxies, forming gas clouds that give birth to the next generation of stars. Galactic archaeology – the structure and behaviour of galaxies across time and the composition of the constituent stars – and the of ejecta in X-rays and gamma-rays will help to clarify this picture.

A BETTER UNDERSTANDING OF FUNDAMENTAL THEORY THE NATURE OF NEUTRON STARS? Atomic nuclei are tiny complex ‘many-body’ Neutron stars are extreme objects thought to systems whose properties are mediated by be composed of various kinds of exotic nuclear or electromagnetism, and the strong and weak quark matter, which need to be explored further nuclear forces. The daunting challenge for through computer simulations, in high-energy theorists is to describe nuclei in terms of these experiments, and observations of neutron-star interactions, and in extreme astrophysical phenomena. environments. Nevertheless, they do act as important quantum laboratories for exploring the THE ROLE OF BINARY SYSTEMS fundamental laws of Nature. About half of all stars form in pairs or multiples, Antony Mezzacappa/ORNL and stellar evolution is changed when stars are WHAT TRIGGERED THE BIRTH OF OUR AND close together. Our models for the enrichment OTHER SOLAR SYSTEMS? of the Universe with heavy elements currently The current thought is that a nearby supernova ignore interactions between stars in binary triggered the condensation of our Sun and systems. The outer material of a giant star could the planets from a giant molecular cloud, and be quickly siphoned off by the gravitational pull provided some of the heavy elements we are of its companion. If one companion is a neutron familiar with. This is supported by the fact that star, its gravitational pull will suck hydrogen and the of iron-60, nickel-60, has been helium from its partner onto its surface causing a found on Earth. Iron-60, which has a half-life of Computer simulation of a supernova core collapse runaway thermonuclear explosion. It is proposed 2.6 million years, could have been created only and shockwave that the high density of protons would trigger under supernova conditions. We do not know nuclear reactions involving the rapid capture of whether similar events are essential to make other

Chandra/NuSTAR/NASA protons (the rp-process) to create unusual short- planets in the Galaxy with the right proportions of lived proton-rich nuclei. Such species need to be elements for life. studied in accelerator-based experiments. WHAT IS THE ROLE OF RADIOACTIVE WHAT ABOUT THE SPECIAL CASE OF ELEMENTS IN THE EARTH’S EVOLUTION? SUPERNOVA TYPE-IA EXPLOSIONS? Radioactivity generated in the Earth’s interior Detecting the light emissions of the ‘standard keeps it liquid and is responsible for its geological candles’ of supernovae type Ia in the early activity. We do not know to what degree the Universe has been the main evidence for the radioactive elements such as uranium influenced idea that its expansion rate is accelerating due the structure and water content in the early to ’dark energy’ pushing it apart. However, in a Earth’s history. young universe when the proportions of heavier elements – in particular, carbon and oxygen – were lower, the supernovae mechanism could have been slightly different, making these objects less reliable cosmic measuring sticks. Thermonuclear re-ignition also happens in colliding binaries composed of two white dwarfs. How can we extrapolate the different candidate supernova models to the early low-metal-content Universe if we do not understand each of them? The Cassiopeia A supernova remnant showing X-ray emissions from heated iron Radioactivity drives tectonic plate activity (red), silicon and magnesium (green) and titanium-44 (blue) FUTURE PROJECTS 10 AND SPIN-OFFS AN EXCITING FUTURE ALTHOUGH THERE HAVE BEEN TREMENDOUS ADVANCES IN NUCLEAR ASTROPHYSICS, THERE IS MUCH MORE TO BE DONE

rogress in nuclear astrophysics is truly multi-disciplinary and multi-national: advances in astronomical instrumentation are Pgenerating ever-improving imaging and spectroscopy over both wider and deeper fields of view; high-precision analytical equipment increasingly allows us to measure minuscule amounts of rare isotopes in terrestrial rocks and meteorites; and sophisticated accelerator systems and detectors potentially provide the tools to probe unusual, transient nuclei and reactions. All this research is brought together and complemented by The GAIA spacecraft theoretical work, often requiring high-performance computing.

Further progress can be achieved through a LAMOST – the recently commissioned Large Sky greater synthesis of research efforts across Area Multi-Object Fibre Spectroscopic Telescope the disciplines, based on focused collaboration in China is carrying out a five-year spectroscopic between different expert groups. The education survey of 10 million stars in the Milky Way. of young scientists needs to be enriched ALMA – the international Atacama Large with specialised interdisciplinary courses and Millimetre Array, under construction in Chile, will workshops. Along this line, two initiatives have analyse the composition of gas clouds where been set up by the European Science Foundation: stars are born. EuroGenesis (www.esf.org/index.php?id=5456), e-ELT – the 39-metre European Extremely Large which addresses the origin of the elements and Telescope, also to be built in Chile, will be ready in the nuclear history of the Universe; and CompStar the early 2020s, will study in spectroscopic detail (http://compstar-esf.org), focusing on compact the birth and evolution of stars and planets. stars and supernovae. INTEGRAL carries the only current telescope which can measure the variety of gamma-rays from cosmic radioactive nuclei; this ESA mission CURRENT AND was launched in 2002 and may continue into the next decade. FUTURE PROJECTS JWST – the 6.5-metre James Webb Space Below are some international projects that will Telescope, to be launched in 2018, will benefit nuclear astrophysics: complement terrestrial telescopes from space, to reach the earliest stellar generations. ASTRONOMICAL OBSERVATORIES NuSTAR – the NASA Nuclear Spectroscopic Improved (multi-object) spectrometers at all Telescope Array 2012 mission maps in X-rays wavelengths will provide extensive information on newly synthesised titanium-44 in the debris of the origin of the elements: nearby young supernovae. Gaia – the ESA Gaia spacecraft, launched ASTRO-H and ATHENA are Japanese in December 2013 is surveying a billion stars and European X-ray spectroscopy projects Working at the GANIL nuclear in our Galaxy, and will provide spectroscopic respectively, planned for launch between research facility in France information on and evolution. 2015 and 2028, which will measure the hot interstellar gas related to regions where nucleosynthesis happens.

LABORATORY ANALYSIS New generations of instruments capable of probing material with nanometre-resolution are being developed to measure pre-solar grains more efficiently. Lasers are used to measure the precise composition of selected isotopes in samples.

The FAIR facility for nuclear research in Germany 11

SPIN-OFFS AND RELEVANCE FOR SOCIETY The technology and skills developed for nuclear astrophysics research are helping to find solutions to many of the challenges our society faces today.

HEALTH ENVIRONMENT AND ACCELERATOR-BASED RESEARCH Detectors developed for nuclear ANALYSIS A new generation of facilities will enable physics have been adapted for The evolving global climate experiments probing nucleosynthesis, and the medical imaging and diagnosis: and our effect on it is of great extreme conditions in which they occur, to be MRI (magnetic resonance importance. Technologies carried out: imaging), PET (positron from astrophysics and nuclear Radioactive ion beams – several European emission tomography) and CT physics have improved tools for nuclear research laboratories, including GSI (computer-aided tomography). remote-sensing. (FAIR) in Germany, CERN (HIE-ISOLDE) in Beams of atomic nuclei are Radioactivity from both Switzerland, EURISOL (several European sites also used to destroy cancerous natural events, such as hope to host this next-generation experiment), tumours, and radiotherapy volcanoes, and manmade and Legnaro (SPES) in Italy, open a new era with based on injections of sources are monitored. next-generation facilities: These create nuclei radioactive substances is a part Measurements of trace isotopes never made before, and allow their properties of cancer treatment. can track subsurface water to be determined – essential for understanding Ionising and nuclear radiation flows. nuclear reactions in cosmic explosions. is also used to sterilise medical Detecting minute amounts FAIR – the Facility for Antiproton and equipment, household items of characteristic isotopes Ion Research will host a range of projects and food, by utilising their lethal was pioneered in nuclear enabling new research on the properties of effects on microbes. astrophysics laboratories, and dense and atomic structure in now allows us to identify art extreme electromagnetic fields, advancing our COMPUTING AND forgeries, determine the age of understanding of neutron stars and of plasma INFORMATION PROCESSING artefacts and materials, analyse conditions inside stars and planets. The computational tools geological samples, and monitor LUNA-MV – the LUNA Collaboration is developed by researchers environmental pollution. developing a more powerful accelerator in the modelling stellar interiors Security has been improved Gran Sasso underground laboratory to measure and supernovae explosions by detectors and analytical accurately the very slow reactions associated with have inspired a variety of techniques from nuclear hydrogen burning. computing methods used in, astrophysics that can track Neutron sources – more intense neutron beams for example, medical imaging sensitive materials at national are being developed, such as the European and engineering, or simply to borders, and scan cargo Source, FRANZ and nTOF-EAR2 provide faster internet support and baggage for explosives, at CERN, which will be capable of measuring and faster processors. radioactive or fissile materials. neutron-capture reactions. Short-lived radioisotopes ELI – one component of the planned European ENERGY can probe manufacturing laser facility, the Extreme Light Infrastructure, Energy supply is one of the processes and analyse product will be built in Romania and dedicated to nuclear biggest challenges for the next performance, for example, wear physics experiments. decades, and many countries and tear in engine components.. will continue to rely on nuclear COMPUTING AND THEORY power. The techniques of A SKILLED WORKFORCE Advances in computers are the key to nuclear astrophysics are used Understanding the puzzles of developments of the complex theories of to improve the efficiency and the Universe attracts talented nuclear structure, supernova explosions, and safety of nuclear reactors, and students to study physics in cosmic evolution of the abundance of the technology is now available to an international and multi- elements: superfast calculations enable 'clean' the radioactive waste disciplinary environment. This theories and their parameters to be widely so far generated. In the future, training produces highly-skilled explored, and to guide experiments and reactors employing fusion individuals with the analytical compare their results with theoretical predictions. reactions like those in the and technical abilities needed Also support for databases of thousands of nuclei Sun will generate safe nuclear by industry and government and their reactions, and advanced graphics- energy. to solve the problems faced by processing to visualise complex data or theories, society today. are key drivers of the field. AUSTRIA ISRAEL This brochure was supported by TU Vienna Hebrew U Jerusalem the European Science Foundation, VERA Vienna Tel Aviv U as a spin-off from its EuroGENESIS Weizmann I Rehovot BELGIUM programme and a service to Brussels Observatory ITALY the entire nuclear astrophysics ISOL@MYRRHA, Mol Arcetri O community. KU Leuven IAS Rome Liege University INFN Frascati www.esf.org/eurogenesis ULB Brussels LNGS Gran Sasso OA Roma European Science Foundation CROATIA OA Teramo RBI Zagreb U Bologna 1 quai Lezay Marnésia U Zagreb U Catania BP 90015 U Naples F-67080 Strasbourg Cedex CZECH REPUBLIC U Perugia Astronomical Inst. Prague U Pisa France U Torino DENMARK U Trieste DCC Copenhagen FURTHER INFORMATION U Aarhus NETHERLANDS Website: http://origin-of-the- Radboud U Nijmegen elements.eu/European Nuclear FINLAND SRON Utrecht U Helsinki U Amsterdam Astrophysics (EU) U Jyväskylä U Oulu PORTUGAL COMMUNITY INFORMATION U Coimbra FRANCE U Lisbon Throughout Europe, about 100 research CEA Saclay groups with 225 senior scientists from CSNSM Orsay ROMANIA 19 countries are actively involved in this Ganil Horia Hulubei Bucharest IAP Paris science theme as of today. More are IPHC Strasbourg SPAIN likely to be integrated in coming years, as IPN Orsay IA Andalucia astronomical facilities such as the Sloan IRAP Toulouse IA Canarias Digital Sky Survey or the Gaia space Observatoire de Paris ICE Bellaterra Paris Nat Hist Museum IEM Madrid mission, and nuclear research facilities U Nice IFIC Valencia such as RIKEN, FAIR, and FRIB, add major UPJV U Alicante data for nuclei of the Universe. Research U Barcelona groups are supported in their home GERMANY U Huelva AIP Potsdam U Seville countries – Austria, Belgium, Croatia, the ESO Garching U Valencia Czech Republic, Denmark, Finland, France, GSI Darmstadt UAM Madrid Germany, Greece, Hungary, Israel, Italy, HZDR Rossendorf UCM Madrid Netherlands, Portugal, Romania, Spain, LMU München UGr Granada MPA Garching UPC Barcelona Sweden, Switzerland, and the UK – and MPE Garching USC Santiago de Compostela by their home institutions, often through MPICH Mainz specific research grants. International MPP Munich SWEDEN research networks and organisations MPIK Heidelberg Lund O TU Berlin Onsala Space O are dedicated to this field (for example, TU Darmstadt Stockholm U HGF’s NAVI in Germany and JINA in the TU Dresden Uppsala U US, and UKAKUREN in Japan and Russia). TU München International conferences typically attract U Bochum SWITZERLAND U Bonn CERN Geneva several hundred scientists (for example, U Erlangen-Bamberg EPFL Lausanne Nuclei in the Cosmos, with a history of 13 U Frankfurt ETH Zürich bi-annual conferences so far). U Giessen U Basel U Heidelberg U Bern U Köln U Geneva U Tübingen U Würzburg UK Liverpool John Moores U GREECE Queen’s U Belfast INP Demokritos U Cambridge U Thessaloniki U Central Lancashire U Edinburgh HUNGARY U Hertfordshire ELTE University Budapest U Keele Editor: MTA Atomki Debrecen U Manchester Nina Hall, [email protected] U West Hungary U Portsmouth Design: U Surrey h2o Creative Communications U York September 2014 UC London