Astroparticle Physics in Europe

1 Astroparticle Physics in Europe A Roadmap Draft October 3, 2006 2 3 On this Roadmap The Steering Committee of ApPEC (Astroparticle Physics European Coordination) has charged the ApPEC Peer Review Committee (PRC) in 2005 to prepare a roadmap for astroparticle physics in Europe* which covers the next decade. The need for such a readmap arises since projects in astroparticle physics move to ever larger sensitivity and scale, with costs of individual projects on the 100 M€ scale or beyond. The roadmap presented here was prepared by the PRC between October 2005 and October 2006. As a first step towards the roadmap, the state of the experiments in the field was evaluated using a questionnaire filled out by the spokespersons of all astroparticle experiments in Europe, or with European participation (http://www. …….).. Based on this information, on input from the proponents and on presentations given to ApPEC in the last years, the most promising research areas and instrumental approaches were identified. A town meeting in Munich in 2005 served to discuss and iterate these initial concepts with the community at large. The recommendations given in the roadmap were in several stages iterated in particular with the spokespersons of the experiments as well as with the ApPEC Steering Committee. The resulting ApPEC roadmap marks the first stage of a strategy process which foresees a “second stage” roadmap in July 2008. This second stage will be coordinated within ASPERA, an FP6 ERA-Network, with the aim to give detailed implementation scenarios and priorities. The present “first stage” roadmap describes the status and desirable options for the next decade and will help to define the financial and organizational conditions to reach the envisaged goals. This represents an important input to the second stage of the roadmap process. We argue that physics prospects and worldwide competition suggest a significant increase in funding for astroparticle physics. In 2008, the consolidation of funding options and the further evolved status of the projects will allow much better prioritization and staging recommendations for the 30-800 M€ projects to be constructed after 2010. The ASPERA stage of the roadmap will be supplemented by more detailed data on human resources, budget, milestones and the world situation. * Europe – in contrast to its geographical meaning – in this roadmap does not include Russia (or only insofar as Western groups participate in Russian experiments). 4 5 A Roadmap for Astroparticle Physics in Europe Content Executive Summary 1. Introduction 2. Cosmology and the Early Universe 2.1 Introduction 2.2 The cosmic inventory 2.3 The links to particle physics 3. Particle Properties 3.1 Introduction 3.2 Dark Matter and other exotic particles 3.3 Proton decay 3.4 The properties of neutrinos 4. Neutrinos from the Sun, Supernovae and the Earth 4.1 Introduction 4.2 Solar neutrinos 4.3 Geo-neutrinos 4.4 Neutrinos and Supernovae 4.5 Next generation multi-purpose neutrino detectors 5. The non-thermal Universe: cosmic rays, gamma rays, and neutrinos 5.1 Introduction 5.2 Charged cosmic rays 5.3 High energy gamma ray astronomy 5.4 High energy neutrino astronomy 6. Gravitation Waves 6.1 Introduction 6.2 The detection of gravitational waves 7. Recommendations Appendix 1: Members of the Roadmap Committee Appendix 2: Statistical data on astroparticle activities in Europe Appendix 3: Infrastructure for underground experiments in Europe Appendix 4: Glossar on European Initiatives in the field of astroparticle physics 6 7 Executive Summary Initial triumphs of Astroparticle Physics In 2002, Ray Davis and Masatoshi Koshiba were awarded the Nobel Prize in Physics for opening the neutrino window to the Universe, specifically for the detection of neutrinos from the Sun and the Supernova SN1987A in the Large Magellanic Cloud. Their work was a unique synthesis of particle physics and astrophysics. Solar neutrinos also provided the first clear evidence that neutrinos have mass. It is this interdisciplinary field at the intersection of particle physics, astronomy and cosmology which has been christened astroparticle physics. The detection of solar and Supernova neutrinos is not the only new window to the Universe opened by astroparticle physics. Another one is that of high energetic gamma rays recorded by ground based Cherenkov telescopes. From the first source detected in 1989, three sources known in 1996, to nearly 40 sources identified by the end of 2006, the high energy sky has revealed a stunning richness of new phenomena and puzzling details. Other branches of astroparticle physics did not yet provide such gold-plated discoveries but moved into unprecedented sensitivity regions with rapidly increasing discovery potential – like the search for dark matter particles, the search for decaying protons or the attempt to determine the absolute values of neutrino masses. Given its interdisciplinary approach and the overlap with astrophysics, particle physics and cosmology, a concise definition of which experiments may be considered “astroparticle physics” is difficult and perhaps not even desirable. For the purpose of this roadmap, the ApPEC Roadmap Committee adopted the assignments grown historically and being practiced in most European countries. The basic questions Recommendations for the evolution of the field over the next decade were formulated by addressing a set of basic questions: 1) What is the Universe made of? In particular: What is dark matter? 2) Do protons have a finite life time? 3) What are the properties of neutrinos? What is their role in cosmic evolution? 4) What do neutrinos tell us about the interior of the Sun and the Earth, and about Supernova explosions? 5) What is the origin of cosmic rays ? What is the view of the sky at extreme energies ? 6) Can we detect gravitational waves ? What will they tell us about violent cosmic processes and about the nature of gravity? An answer to any of these questions would mark a major break-through in understanding the Universe and would open an entirely new field of research on its own. 8 Astroparticle physics at the dawn of a golden decade ? Most of the fields of astroparticle physics have moved from infancy to technological maturity: the past one or two decades have born the instruments and methods for doing science with high discovery potential. We observe an accelerated increase in sensitivity in nearly all fields – be it neutrino-less double beta decay, dark matter research, search for high energy neutrinos, gamma rays and cosmic rays, or gravitational waves – just to mention a few. The long pioneering period to prepare methods and technologies is expected to pay off over the next 5-15 years. This will not only need substantial investment in large detectors but also in the necessary infrastructures – underground laboratories (providing the infrastructure to perform, e.g., the search for double beta decay, “direct” searches for dark matter, investigation of neutrinos from the Sun or supernovae, or detectors searching for proton decay) and telescopes/observatories (like neutrino telescopes underwater and -ice, telescope arrays for gamma rays or the largest air shower detectors for charged cosmic rays). Next-stage projects need strong coordination and cooperation The price tag of frontline astroparticle projects requires international collaboration, as does the realization of the infrastructure. Cubic-kilometre neutrino telescopes, large gamma ray observatories, Megaton detectors for proton decay, or ultimate low-temperature devices to search for dark matter particles or neutrino-less double beta decay are in the range of 50-800 M€. Cooperation is the only way (a) to achieve the critical scale for projects which require budgets and manpower not available to a single nation and (b) to avoid duplication of resources and structures. Major European initiatives in the next decade: a scenario The European astroparticle community has a lead position in many fields. The roadmap and it’s recommendations illustrate this claim in detail. We assume that the process of cooperation and coordination converges to the following major (cost > 50 M€) activities between 2009 and 2015. The Table gives a summary information on the projects, the following text a short background and explanation. 9 Field/ Cost scale Desirable Remarks Experiments (M€) start of construction Dark Matter Search: 2 experiments (different Low background 60-100 M€ 2011-2013 nuclei, different techniques), experiments with 1-ton e.g. 1 bolometric, 1 noble mass liquid; more than 2 worldwide. Proton decay and low - multi-purpose energy neutrino Civil - 3 different technological astronomy: engineering: options Large infrastructure for p- 400-800 M€ 2012-2013 - needs huge new excavation decay and ν astronomy on - most of expenditures likely the 100kt-1Mton scale after 2015 - worldwide sharing Properties of neutrinos: - explore inverse hierarchy Double beta experiments 60-80 M€ 2011-2013 scenario - 2 experiments with different nuclei (and desirably more worldwide) The high energy universe: Gamma rays: Cherenkov Telescope Array 100 M€ (South) first site Physics potential well CTA 50 M€ (North) in 2010 defined by rich physics from present gamma experiments Charged Cosmic Rays: Auger North 85 M€ 2009 Confirmation of physics potential from Auger South results expected in 2007 Neutrinos: KM3NeT 300 M€ 2011 FP6 design study. Confirmation of physics potential from IceCube and gamma ray telescopes expected in 2008-2010 Gravitational Waves: Civil Third generation

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