The GBAR Collaboration gathers around 50 members from 17 Institutes, with the goal of measuring the acceleration of hydrogen antiatoms in the Earth gravitational field. The experiment has been installed at CERN at the AD-ELENA ring.
It produced its first antihydrogen beam in 2022: P. Adrich et al., Eur. Phys. J. C 83, 1004 (2023).
SPP physicists are at the origin of the GBAR project. Specifically the SPP group has initially developed a novel high-intensity source of positrons, based on an electron linac, managed to store these positrons in a Penning trap, and to produce positronium from their interactions with a porous SiO2 substrate.
The H.E.S.S. Collaboration gathers more than 170 scientists from 32 institutes of 12 countries. Four 12 m-telescopes, installed since 2002 in Namibia, are in operation to observe Cherenkov light produced by interaction of high-energy gamma rays with the upper atmosphere. Since 2012, a fifth telescope of 28 m-diameter completes the network (H.E.S.S.-2). H.E.S.S. observations have allowed the discovery of more than a hundred gamma ray sources. The CTA project, which will encompass about a hundred telescopes of various sizes (6, 12 and 24 m in diameter) in the southern hemisphere, and about thirty in the northern hemisphere, is being put in place.
The SPP group has contributed to the H.E.S.S.-2 level-2 trigger development, and concentrates on the indirect search for dark matter or exotic particles in the spectra of observed objects, in particular the Galactic center. In CTA, the group participates and supervises the development of a camera (Nectarcam) for middle-size telescopes, and contributes to the design and production of mirrors.
The Astrophysical Plasma Modeling team aims to understand astrophysical processes driven by gravity, radiative hydrodynamics, and magnetohydrodynamics (MHD), and to characterize their observable consequences. Their theoretical approach is physics-centered and leverages the most suitable numerical, analytical, and experimental tools to address the complexity of turbulence, shocks, and instabilities.
The ATLAS Collaboration gathers close to 3,000 physicists, from 174 institutes in 38 countries. ATLAS is one of the two general-purpose experiments at the CERN Large Hadron Collider (LHC). ATLAS has recorded proton-proton collision data at 7 TeV center-of-mass energy in 2010 and 2011, then at 8 TeV in 2012 (Run 1). The Higgs boson discovery was announced at CERN in July 2012. The Run 2 of the LHC, which started in 2015 at 13 TeV energy, is on going until end of 2018.
The ATLAS group at IRFU has contributed to the design and construction of the muon spectrometer and the liquid Argon electromagnetic calorimeter. The group is active in data analysis: properties of the Higgs boson, tests of the Standard Model, and search for physics beyond the Standard Model. IRFU physicists are also involved in the upgrades of the ATLAS detector for the high-luminosity phases of the LHC, in particular they are building part of a novel forward muon detector known as NSW (New Small Wheels) and improving the trigger capabilities of the electromagnetic calorimeter.
The CMS Collaboration gathers close to 2,500 physicists, from 180 institutes in 43 countries. CMS is one of the two general-purpose experiments at the CERN Large Hadron Collider (LHC). CMS has recorded proton-proton collision data at 7 TeV center-of-mass energy in 2010 and 2011, then at 8 TeV in 2012 (Run 1). The Higgs boson discovery was announced at CERN in July 2012. The Run 2 of the LHC, which started in 2015 at 13 TeV energy, is on going until end of 2018. CMS has recorded more data in 2016 than during Run-1.
IRFU engineers have designed the CMS magnet, which is the largest supraconducting solenoidal magnet in the World : 6 m in diameter, 12 m long, yielding a 3.8 T homogeneous and uniform magnetic field in the detection volume, which corresponds to more than 2 GJ of stored magnetic energy.
The CMS group at IRFU has participated to the design and construction of the electromagnetic calorimeter, and in particular of the laser system to monitor the transparency of the crystals. The group is active in data analysis: Standard Model physics, study of the Higgs boson, search for non-standard physics.
The T2K Collaboration gathers about 500 physicists from 59 institutes in 11 countries. T2K is a longue-baseline off-axis neutrino experiment for the study of neutrino oscillations using a beam of muonic neutrinos produced at the J-PARC Japanese facility, and measured at short distance (280 m) by the ND280 detectors and at large distance (295 km) by the Super Kamiokande water-Cherenkov detector. The data taking started in 2009 and will extend until 2020.
The Irfu group has participated to the design and construction of the set of three large TPCs of the near detector ND280, and is involved in data analysis of both near and far detectors. The group is noticeably interested in precise measurements of neutrino interaction cross sections on various targets, with the goal of reducing systematic uncertainties in oscillation parameter measurements. Following a major involvement in the design studies for the next generation long-baseline experiments in the context of the European LAGUNA-LBNO project, the group now participates to the construction of the dual-phase liquid argon prototype WA105 at CERN, whose aim is to validate the technology for the far detector of the long baseline project DUNE (Deep Underground Neutrino Experiment) in the US.
The group shows interest in the new phase of the T2K experiment, with a more intense neutrino beam from J-PARC to Super Kamiokande, and more performing near detectors. The groupe entertains close links with the Hyper Kamiokande project, a megaton-scale water-Cherenkov detector that could take over Super Kamiokande and give access to a significant observation of CP violation in the leptonic sector using neutrinos from J-PARC.
Physicists of the SPP Cosmology group use several cosmological probes to constrain the energy content of the Universe: the baryon acoustic oscillation (BAO), with participation to the BOSS, eBOSS, and DESI experiments ; type 1A supernovae within the SNLS experiment ; and galaxy clusters with the data of the Planck satellite.
The BAO studies exploit quasars, with which one can explore distant regions (with redshifts between 1 and 3), by looking at the Lyman-α, which map the intergalactic hydrogen clouds through which the emitted light is travelling. The BOSS project of the SDSS-III (Sloan Digital Sky Survey) has ended data taking, to allow for eBOSS of the SDSS-IV to begin. The DESI project will start taking data at the turn of 2020. The Institute is responsible for the production of the cryostats for the ten triple-spectrometers of DESI.
The SNLS activities are focused on the photometric study of SN1A, and the investigation of the galileon hypothesis, in collaboration with physicists of the CMS group.
As for the Planck data, the SPP group takes responsibility for producing a catalog of galaxy clusters, in close collaboration with groups of the SAp and the APC laboratory.
The "Cosmology and Galaxy Evolution" team focuses on the study of the formation, evolution, and physical properties of large cosmological structures, galaxy clusters, galaxies themselves, and their internal structures, extending to large-scale star formation. These structures are studied across cosmic time, from the birth of the first galaxies to the closest objects today. These studies are conducted using multi-wavelength observations with state-of-the-art observatories (ALMA, JWST, VLT, IRAM, and Euclid), complemented by advanced cosmological and galaxy evolution simulations using Europe's largest supercomputers. Continuous interaction between observations and simulations is sought to maximize data interpretation and provide the best constraints for structure formation models.
The theme of the Universe's energy content, primarily focused on questions of dark matter, dark energy, and gravity, is a rapidly growing activity within the Cosmology and Statistics team, reflected by leading contributions to major international collaborations.
« Irfu's mechanical and thermal design office »
The Design, studies and preliminary projects laboratory (LCAP) is the "mechanical and thermal design office" in charge of the architecture and design of instruments, at the service of Irfu's projects.
The International Linear Collider (ILC) is one of the collider projects envisioned as the next large machine for particle physics, and the in-depth study of the electroweak symmetry breaking sector.
The ILC is a linear electron-positron collider located in Japan, whose physics programme spans several decades, starting around 2030. In a first phase the ILC will operate at an collision energy of 250 GeV, for the precise study of the properties of the Higgs boson produced in association with a Z boson. In subsequent phases, the energy will be pushed to 360 GeV, for precise measurements of the top quark at the pair production threshold, the at 500 GeV and above, for the study of the Higgs boson produced by vector boson fusion and the Higgs boson pair production. The ILC displays a strong discovery potential and is complementary to the HL-LHC in terms of sensitivity to the physics beyond the Standard Model.
In the past fifteen years, Irfu engineers have played a key role in the selection of the cryogenic acceleration technology for the ILC. Recently, in the context of the XFEL project at DESY in Germany, Irfu and its partners have demonstrated the production and assembly of a large number of cryomodules presenting the accelerating fields that are required for an ILC (above 25 MV/m).
The detector R&D led at Irfu for the ILD experiment at the ILC is focused on the development of a TPC tracking detector with a micro-pattern gas detector (MPGD) readout. The considered MPGD is Micromegas, a technology that was initiated by Irfu physicists and engineers.
The RD51 Collaboration at CERN, in which Irfu physicists have a leadership role, is a R&D effort devoted to the development of the MPGD technology for particle physics detectors at future colliders.
The AIM "Dynamics of Stars, Exoplanets and their Environment" team aims to develop cutting-edge research to understand the internal and external structure, dynamics, and evolution of the Sun, stars, and planets, as well as the atmospheres of exoplanets. Additionally, the research teams study gravitational, magnetic, and radiative interactions at different scales between these celestial bodies and their environment, as well as the orbital architecture of planetary systems. This research is based on innovative and synergistic theoretical predictions, nonlinear 3D HPC simulations, observational data analysis that constrains the models, and the development of instruments for dedicated space missions (SOHO, Solar Orbiter, JWST, PLATO, and ARIEL).
The laboratory is structured around three areas of expertise: electrical engineering, power electronics and instrumentation. These areas of expertise are divided into the following activities:
The size and complexity of physics experiments lead the laboratory to rely more and more on the industrial environment through subcontracting.
Specific means and equipment: the laboratory has 3 workstations equipped with SEE-Electrical and Autocad softwares to carry out electrotechnical studies, a room dedicated to electrotechnical achievements, a coordinate-measuring machine, a laser tracker, cryostats, vacuum equipment and a set of physical measuring devices...
CaLIPSO is a medical imaging project aiming at a breakthrough in high-spatial-resolution Positron Emission Tomography (PET). The CaLIPSO concept for the detection of 511 keV gamma rays is based on the precise 3D localisation of the photoelectron in an organometallic liquid, associated with ultra fast electronics. This detector R&D activity is on-going at IRFU since 2009, with very promising results.
The scientific objective of the High Energy Cosmic Phenomena team is the discovery, characterization, classification, and understanding—from the perspective of fundamental physics—of the most energetic and violent astrophysical phenomena. These sources are usually revealed by their radiations in the high-energy domain (X-rays and γ-rays).
Staff : 7 agents
The Industry Liaison Laboratory (ILL) is the interface between the engineering and design office, scientists, the procurement division of CEA and industrial companies. Its main purpose is to follow the studies and/or the manufacturing, entrusted to industrial companies, of complex mechanical equipment destined to physics instrumentation in the following fields :
The ILL main activity and expertise fields are described below.
The instrumental electronics laboratory is in charge of developing electronic systems to measure, control or secure equipment for research in physics.
The LEMID is a group of about fifteen permanent employees, composed of engineers and technicians, whose main activities cover the development process of mechanical components for detection systems, the assembly of the detectors themselves, and the integration of detection systems on-site. Besides, the LEMID welcomes and trains students, interns, apprentices, in the frame of their education.
The laboratory’s skills in design combine the fields of mechanics and electronics in order to create detectors matching physics’ needs.
The main purpose of the group in charge of software engineering for scientific applications (Lilas) is to develop the software tools and modules needed by the physics experiments in which Irfu is involved. Software modules play an ever increasing role in the systems developed by Irfu for its scientific projects and they are also expected to address ever increasing demands for performance, durability and reliability. The vocation of Lilas is therefore to maintain inside the Institute and over many years a pool of advanced technological skills that are most relevant to the projects in which Irfu is involved.
Consequently, apart from the proper design and implementation activities directly linked to the projects, the group needs to maintain R&D and technological watch activities allowing its engineers to acquire and expand cutting edge techniques, tools and methodologies in order to rationalize and professionalize the production of software for scientific systems.
The task of LCSE is to master cryogenics technology applied to superconducting magnets, accelerating cavities, physics detectors (cryogenic target systems, calorimeters), and the production and distribution of liquid helium.
For its own developments, and to meet project needs for development and testing, the laboratory designs, builds, and operates several test and characterization stations to determine the mechanical, thermal (see figure), and electrical properties of complete cryogenic subassemblies (such as magnets within cryostats, cryomodules, …), or their basic components (coil cold mass, RF cavities, instrumentation). These stations of various types and sizes use low-temperature refrigeration systems, such as refrigerators or cryogenerators, using the following fluids: helium I and II, nitrogen, argon, neon, or hydrogen.
More specific R&D activities are being carried out on the study and improvement of low-temperature heat transfer systems (helium II in porous media, PHP (pulsating heat pipes) with different gases at cryogenic temperatures), on two-phase flows (thermosiphon with helium I or nitrogen), on the thermohydraulics during magnet "quench", and on the development of cryogenic targets in liquid or solid hydrogen.
At the end of 2020, laboratory staff consisted of 16 engineers, two doctoral students, and six technicians.
LEARN staffs study the process and mechanisms at work in nuclear reactions and provide expertise to address issues in related topics or societal issues. Activities include the description and prediction of elementary-particle- (photons, neutrinos) or nucleon-induced nuclear reactions and development of the experimental and modeling tools needed for those studies.
The Laboratory for Superconducting Magnet Research (LEAS) offers its expertise in magnetic fields to IRFU physicists, with a staff of 7 technicians, 20 engineers and one PhD student at the end of 2015.
The laboratory teams are responsible for the design and project management of superconducting magnets for experimental facilities, especially large magnets or those with high magnetic fields.
In designing superconducting magnets, LEAS applies its expertise to the optimization of coil geometry, conductor design, mechanical, electromagnetic, and thermal calculations, and magnetic protection in the event of quench. In addition to designing magnets, LEAS has the capacity to manage large projects, to develop magnets and integrate them into cryostats, and to supervise specific industrial projects. Magnets are inspected jointly with the Cryogenics Laboratory and Test Stations (LCSE). Measurement tasks include analyses of tests at ambient and cryogenic temperatures, including quench analyses and magnetic measurements.
Major projects completed recently, such as the GLAD dipole for the R3B spectrometer (reaching completion), or the solenoid coil for the Iseult imaging system, represent R&D work that keeps LEAS staff at its highest level of achievement.
The demand for high magnetic fields is also coming from laboratories such as the French National High Magnetic Field Laboratory (LNCMI) in Grenoble or CERN, in view of future circular accelerators such as the FCC (Future Circular Collider). This demand can only be satisfied by using niobium-tin (Nb3Sn), or high-temperature superconductors based on rare earth elements. These materials have been under active research and development for several years.
Significant developments also involve magnesium diboride (MgB2), which could eventually compete economically with niobium-titanium (NbTi).
The Accelerator Design and Development Laboratory brings together DACM expertise and skills in the design, construction and testing of systems used to produce, transport, accelerate and characterize high-intensity or high-energy charged-particle beams.
As of December 31, 2015, LEDA employed 22 engineers, seven technicians, one PhD student and one engineering intern, working in the following teams:
- A team of experts in beam modeling applied to linear and circular accelerators, in the presence of collective effects such as space charge or wake fields, and in electromagnetic calculations applied to electrostatic, magnetic and radiofrequency systems.
- A technical team experienced in accelerator installation, mechanical assembly and cooling.
- An experimental team specialized in setting up and operating sources and injectors.
- An experimental team of experts for measuring beam parameters, involving the design and implementation of innovative diagnostic techniques.
Building the groundwork for future research, LEDA is currently constructing an accelerator for nuclear physics research (FAIR), contributing to the IFMIF and SARAF neutron source projects, designing a radiofrequency quadrupole for the ESS project, exploring the theoretical and technological aspects of the next generation of particle accelerators (HiLumi LHC, FCC and CLIC), and studying laser-plasma acceleration for the CILEX project.
Between 2013 and 2015, an important R&D program was conducted on ion sources through the development of the ALISES 2 source. In the field of beam diagnostics, LEDA contributed to the development of an innovative emittance meter.
During this period, LEDA also developed its technological platforms by building DIVA, a laboratory for diagnostics, vacuum and assembly activities, while improving its ionsource design and test bench (BETSI) and preparing for startup of the high-intensity proton injector, IPHI. These projects were partially financed by the Ile-de-France Regional Council.
The LENA group laboratory conducts experimental programs on the structure and spectroscopy of the nucleus in extreme states, following three research axes:
• the structure of exotic nuclei with neutron halos or skins, low energy resonances, modifications of the standard shell structure,
• shapes and deformations of nuclei, which may have very different shapes in the vicinity of their ground state,
• and the spectroscopy of very heavy nuclei (region of transfermium nuclei and beyond).
The LENA Nuclear Structure Theory Group develops models that aim to extend our understanding of the emergence of nuclear phenomena based on theories of low-energy nuclear interactions. In particular, the scope is to develop a complete interpretation of the experimental results on the nuclear chart by carrying out ab initio calculations.
The Cavity and Cryomodule Development and Integration Laboratory (LIDC2) is a center of expertise within DACM, specialized in research on superconducting accelerator cavities and cryomodule integration. LIDC2 provides expertise to support IRFU projects. The laboratory carries out R&D work required to develop cavities from the perspective of both materials (multilayer and polishing) and surfaces (electropolishing and high-pressure rinsing). It participates in the design and development of cryomodules for both French and international accelerators such as SPIRAL2, XFEL and ESS. It is in charge of integrating these systems from the prototype stage. LIDC2 also manages certain shared DACM resources, such as cleanrooms, the chemical treatment facility, materials characterization laboratories and assembly halls.
A staff of 18 engineers and 11 technicians carries out laboratory operations and projects.
The Accelerator and Hyperfrequency Systems Engineering Laboratory represents DACM’s expertise in the design and construction of high frequency electromagnetic structures and their implementation through the use of appropriate instrumentation. At the end of 2015, laboratory staff consisted of 18 engineers and five technicians.
Laboratory activities involve mainly the development of radiofrequency structures for particle accelerators used in physics research (radiofrequency quadrupoles, superconducting cavities, power couplers with highorder harmonics suppression), as well as the associated qualification tools, including RF power sources and instrumentation. The laboratory also manages certain shared DACM resources, such as SupraTech-CryoHF RF test platforms and the new 352 MHz platform. These activities also cover applications in other fields such as antennas for high-field magnetic resonance imaging.
In carrying out its work, LISAH has access to internal expertise within IRFU in the fields of material sciences, process engineering, mechanical construction, and quality assurance. The laboratory also contributes to other IRFU projects, either by taking charge of an entire work package or by providing technical consultancy services.
The Nucleon Structure Laboratory leads research programs in hadron physics and Quantum Chromodynamics (QCD) with a specific focus on the internal structure of hadrons. Its activities can be classified into three major branches:
The research programs of the Nucleon Structure Laboratory cover in a consistent way all the modern aspects of nucleon structure, from the theoretical motivation of some key problems to the design of the required associated detectors.
The Nucleon Structure Laboratory consists in 24 members, including staff, PhD students and postdocs.
The Quality and Space Integration team supports space projects in terms of Product Assurance and Quality Assurance, as well as AIT (Assembly, Integration, and Testing) activities throughout the development and implementation phases.
The quark-gluon plasma laboratory studies ultra-relativistic heavy-ion collisions to create and characterize the new state of nuclear matter in which the quarks and gluons are deconfined, the quark-gluon plasma (QGP). A few micro-seconds after the Big Bang, the Universe was in such a QGP state. The LQGP participated in the PHENIX experiment at RHIC, BNL and is currently involved in the ALICE experiment at the LHC, CERN. The LQGP is building its future by its strong involvement in the upgrade programs of ALICE, MFT and MUON electronics, and sPHENIX.
The Interface Science and Space Instruments team is at the interface between science and space instruments from design phases to operational flight. They specify instruments, develop data analysis software, and ensure that these instruments meet scientific objectives.
The Double-Chooz collaboration gathers about 160 physicists and engineers from 38 Institutes in 8 countries. Located next to the Chooz nuclear plant in the French Ardennes, the experiment is designed to study neutrino oscillations from the flux of electronic antineutrinos emitted from the two nuclear reactors of the plant. Compared to previous generation reactor neutrino experiments, Double-Chooz uses two detectors rather than one, in order to reduce normalisation uncertainties. One of the detectors is located about 1 km from the cores, while the second one is at about 400 m.
First results with only the far detector were presented in November 2011, showing evidence for an non-zero value of the θ13 mixing angle. In 2016, the Collaboration presented for the first time results based on the analysis of data from the two detectors. The comparison of rates and energy spectra of electronic antineutrinos recorded by the two detectors, which are as alike as they can be, allows a significant reduction of the systematic uncertainties in the measurement of the parameter sin2(2θ13) that governs the oscillation of the electronic flavour to another flavour at short distance. The obtained value is significantly different from zero with a relative precision of 15%, in agreement with the even more precise result by the Daya Bay experiment, in China. The fact that mixing angle θ13 could be measured non-zero with such precision is one of the most striking neutrino physics results in recent years.
In addition, Double Chooz has produced a measurement of the reactor neutrino cross section, irrespective of the oscillation phenomenon, with a relative precision of de 1.2%. This measurement is key to the understanding of the reactor neutrino anomaly, which was revealed by Irfu physicists in 2011. The reactor neutrino anomaly has to do with a systematic deficit of the measured flux of antineutrinos compared to the calculated ones, by the most sophisticated models of antineutrino production in the core of nuclear reactors. One of the proposed hypotheses to solve the anomaly is the existence of a fourth flavour of sterile neutrinos.
Irfu physicists and engineers were at the origin of the Double-Chooz experiment. They have been in charge of the technical coordination, as well as of the design and construction of the various acrylic vessels. The groups has put in place the measurement of the mass of the liquids involved, and has performed compatibility tests for all the materials. SPP physicists are main players in the data analysis and the production of scientific results.
The Double-Chooz experiment will be decommissioned in 2018.
The Nucifer experiment, installed next to the research reactor Osiris at Saclay, was designed to follow the fuel cycle in the core of reactors from the measurement of the flux of antineutrinos, and consequently to provide a tool to survey nuclear plants for non-proliferation purposes. The techniques involved in Nucifer to measure the flux of antineutrinos very close from the core of a reactor have paved the way to the data analysis in Double Chooz.
The CeSOX experiment proposes to position an intense radioactive source of Cerium 144 known as CeANG (for Cerium Antineutrino Generator) beneath the Borexino neutrino detector at the Gran Sasso Laboratory, next to L'Aquila in Italy. The CeANG source is being produced by the P. A. Mayak Company in Russia, and will be delivered early in 2018. The scientific goal of the CeSOX experiment is to demonstrate the existence of a fourth flavour of sterile neutrinos that would elucidate the reactor neutrino anomaly (see above), or to exclude its existence in a significant region of the parameter space.
The Space Systems and Architectures team is responsible for system architecture definition and technical oversight throughout the design, development, and testing of various instrument models.
The "Spectro-Imagers for Space" team conducts R&D on detectors ranging from the far infrared to gamma-ray wavelengths, including bolometers, microcalorimeters, CMOS-MCT, or semiconductors for X-rays and gamma rays.
It can be argued that the astrophysical quest for our origins rests on two pillars: the formation of large structures into galaxies and the formation of stellar systems. The interstellar medium (ISM) is at the heart of this quest, as the initial conditions of protostellar and protoplanetary disks are directly inherited from the ISM, which, in turn, transmits numerous feedback mechanisms from massive stars or energetic events that punctuate the life cycle of galaxies.
Research conducted by the Star Formation and Interstellar Medium team at AIM enables a coherent and self-consistent study of the ISM as a highly heterogeneous, dynamic, magnetized, and multi-phase fabric, whose signatures are detected across multiple wavelengths and at very different spatial scales. This translates directly into diversified observation techniques and a wide range of models and simulations with similar ingredients but specific and complementary focuses.
The Space Electronics Systems Design and Development team is responsible for defining, designing, and developing embedded electronic equipment. They have expertise in defining and sizing electronic system architectures, as well as in analog and digital space electronics, particularly detection chains.
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