General introduction of the laboratory

The Laboratoire AstroParticule et Cosmologie (APC) is a Joint Research Unit (UMR en French) created in 2005. APC brings together about 75 permanent researchers and about 50 engineers, technicians and administrative staff. Including non-permanent staff (PhD students, postdoctoral fellows, foreign visitors), this structure gathers about 200 people. In addition to the University of Paris (UP), it is governed by the CNRS (represented by three of its Institutes: mainly IN2P3, but also INSU and INP), the CEA (DSM/IRFU) and the Paris Observatory, and the French space agency, CNES.

The laboratory is centred around four main themes :

Cosmology: the aim of cosmology is to understand the history and structure of the Universe, in which gravitation plays an important role. The understanding of the primordial universe, the study of the microwave cosmological background and the identification of dark energy are some of the aspects of our research. APC is strongly involved in the Planck space mission and the Qubic experiment in Argentina and the POLARBEAR experiment in Chile, in the wide-field surveys that allow a better understanding of dark energy (the BOSS wide-field survey, the LSST telescope and the Euclid space mission).

Gravitation: With the first detections of LIGO and Virgo, gravitational astronomy became a reality. This new field of astronomy will develop in the next decade with second generation ground-based detectors, in particular Advanced Virgo (and its future improvements) and third generation detectors, with the European Einstein Telescope project, as well as in space with the ESA-led LISA mission. Members of the Gravitation group play an important role in the development of each of these instruments, both at the instrumental level and in the exploitation of scientific data.

High Energy Astrophysics: Violent phenomena in the Universe are studied in order to better understand the physical processes that govern the formation of cosmic structures. The laboratory is strongly involved in the observation of X-rays (SVOM, ATHENA) and gamma rays (INTEGRAL, TARANIS, HESS-CTA), ultra-high energy cosmic rays (JEM-EUSO) and neutrinos (ANTARES-KM3NeT/ARCA).

Neutrinos: these extremely light particles interact very little with matter and are therefore irreplaceable messengers of phenomena occurring at cosmic distances from us. The study of their properties is therefore important for the field of astroparticles. The laboratory is strongly involved in a complete identification of the oscillation phenomenon (DoubleCHOOZ, DUNE, KM3NeT/ORCA). Researchers of the group are also involved in direct dark matter research with the DarkSide experiment.

In addition to the experimental or observational activities described above, the theoretical aspects connected to the topics covered by the laboratory are studied by the Theory group. More specifically, the research covers all theoretical aspects of cosmology and astroparticles, from the foundations of general relativity and unification theories, such as string and branes theory, to the understanding of cosmic acceleration phenomena, the phenomenology of high-energy cosmic particles and neutrino physics. Numerical simulations are a complementary tool for the analysis of complex phenomena, from accretion-ejection around compact objects to the formation of large cosmological structures.

The laboratory also has an extensive program of interdisciplinary collaborations, notably with the geosciences (muography, geoneutrinos and cosmic neutrinos, gravitational detectors for seismometry) in the context of the Laboratory of Excellence UnivEarthS.

APC maintains close ties with the Paris Centre for Physical Cosmology (PCCP) chaired by George Smoot, winner of the 2006 Nobel Prize, which develops research, training and knowledge dissemination activities in the field of cosmology.

R&D and data analysis. The laboratory contributes to astroparticle projects upstream and downstream. Particular importance is therefore given to R&D and data analysis.

In the field of R&D, some strong axes are: bolometry in the millimetre and submillimetre domains, cryogenic microelectronics, photodetection (characterisation of photomultipliers, scintillators for high energies), laser stabilisation.

Data processing also receives special attention. In September 2010, the APC laboratory opened a space data processing centre, the François Arago Centre, to support space missions requiring complex data processing. The Centre, which is closely connected to the CNRS computing centre in Lyon (CC-IN2P3), provides a number of services to its users, such as access to computers, analysis routines, storage servers, distribution of new analysis software and, above all, a team of experts in computer science and data science.

Technical and engineering services. APC's technical services (mechanical, electronic, experimental techniques and IT/computing) allow the laboratory to participate in the design of new experiments, prototyping, construction monitoring, data processing and exploitation. Each project of the laboratory is allocated means that enable it to fulfil the commitments made by the laboratory. The laboratory possesses large-scale equipments : clean rooms (optics, system integration), machining centre, space simulator, low-noise, low-frequency electronics test room and photodetection laboratory.

The APC laboratory is involved in a number of space missions (50% of its technical forces are dedicated to it). This also requires stringent quality control and special attention to project management. Over the last few years, the laboratory has set up a quality and project support unit which monitors quality in the laboratory and supports the laboratory's projects in terms of product assurance analysis methods. In addition, all of the APC's space activities contribute to the know-how of the University of Paris in this field, skills which must be brought together within a space cluster bringing together training and research activities relating to space in all University's components.

Teaching and dissemination of knowledge. The laboratory is particularly attentive to its mission of diffusion of knowledge: to make known the scientific fields approached, the outstanding results, but also the technical achievements and more generally the way in which the laboratory lives from day to day. All the teacher-researchers of the laboratory and some researchers take part in the teachings of the University of Paris. The laboratory also wishes to involve students in its various activities, during internships (about a hundred per year) or theses. The laboratory's website is aimed at a multiplicity of different audiences: the scientific community, but also the general public interested in scientific and technical advances, students of all levels, professors, journalists. APC has also developed an interactive tool, the Virtual Institute of Astroparticles or COSMOVIA, accessible via the web: conferences or courses are accessible, with the possibility of interacting live or consulting the database.

International. The APC laboratory is finally involved in an important network of international collaborations :
- experiments located on four continents
- space missions in liaison with the major space agencies, in particular CNES and the European Space Agency (ESA), but also NASA and the Japanese and Chinese agencies,
- a privileged partnership with major astroparticle physics laboratories including the Laboratoire International Associé (LIA) with KIPAC in Stanford, the Pierre Binetruy Center, an International Research Lab (IRL) in association with the University of Berkeley, LIA ALFA in Argentina, LIA LEPLB with Kurchatov and collaborations with Kavli-IPMU in Japan.

This translates into rich programmes of meetings and exchanges such as the annual cycle of conferences "Cosmological Frontiers in Fundmental Physics" with the Perimeter Institute (Waterloo, Canada) and the Solvay Institutes (Brussels), or the participation in the IDAPP international doctoral programme with a group of Italian universities.