Jun 08, 2020
After more than four years of research and development, design and manufacturing work, the MFT (Muon Forward Tracker), a new detector that will equip the ALICE experiment at the LHC, has seen its construction finalized and is currently under commissioning at CERN.
Apr 29, 2020
Nucleons (protons and neutrons), the components of the atomic nucleus, can be polarized. This means that their spins are preferentially aligned along a quantization axis. The spin is a quantum property of a particle and has its classical analogue in a spinning top. The strong interaction that acts among nucleons in the atomic nucleus is sensitive to the polarization.
Mar 10, 2020
INCL (Liège intranuclear cascade) is a simulation code known for its ability to model light particle-nucleus interactions. It is used in very various fields, such as proton therapy, neutron sources, radioactive ion beams or ADS's (Accelerator Driven Systems). In order to extend its capabilities in the field of higher energy reactions, in connection with cosmic rays or with the study of hypernuclei, a team of physicists led by Irfu has recently developed a new version of the code involving strange particles.
Oct 30, 2019
The FIFRELIN code simulates nuclear fission and de-excitation of the nuclei produced therein. STEREO is a compact neutrino detector that looks for a hypothetical sterile neutrino. Two a priori separate topics developed at CEA, the first at DEN, the second at DRF/Irfu, which have however recently met to achieve unprecedented precision on a crucial ingredient in the detection of neutrinos: the de-excitation of a gadolinium nucleus after the capture of a neutron.
Sep 25, 2019
It is possible to trace the shape of a drum from its vibration modes. Similarly, it is possible to measure the 3D structure of the proton and access its elementary components, quarks and gluons, from observables obtained using deeply virtual Compton scattering experiments off the proton.  By studying this scattering process, we can access this geometric information. This research topic is very active and mobilizes a large international theoretical and experimental community.
Aug 07, 2019
The series of Jefferson Laboratory (USA) experiments dedicated to the measurement of electron-proton elastic scattering showed that the extracted information on the proton structure did not agree when extracted from two kinds of experiments. To reconcile these results, it was suggested that, beyond the exchange of one photon, that is the dominant mechanism, the exchange of a second photon could become important.
Jun 07, 2019
Predicting properties of, e.g., molecules or atomic nuclei from first principles requires to solve the Schrödinger equation with high accuracy. The computing cost to find exact solutions of the Schrödinger equation scales exponentially with the number of particles constituting the system. Thus, with nuclei composed of tens or hundreds of nucleons, it necessitates accurate approximate methods of lower computing cost.
May 22, 2019
Pairing is ubiquitous in physics. From superconductivity to quantum shell structure, coupling particles into pairs is one of nature's preferred ways to lower the energy of a system. New results obtained at the Radioactive Isotope Beam Factory (RIBF, Japan) with the MINOS device, which was conceived and constructed at Irfu, show for the first time that pairing also plays an important role in single-proton removal reactions from neutron-rich nuclei.
May 15, 2019
The predictions of nuclear properties based on a realistic description of the strong interaction is at the heart of the ab initio endeavour in low-energy nuclear theory. Ab initio calculations have long been limited to light nuclei or to nuclei with specific proton and neutron numbers. Theoreticians from Irfu/DPhN have developed novel ab initio methods that led to a significantly increase of the number of nuclei that can be accessed.
May 02, 2019
An international collaboration led by the institutes of CEA-IRFU and of RIKEN (Japan) demonstrates, for the first time, the exceptional stability of the very-neutron rich nickel-78 nucleus and its doubly-magic character. The experiment at RIKEN was made possible by the unique combination of the MINOS device developed at CEA-Irfu and the very exotic beams produced by the RIBF facility of the Japanese accelerator.These results are published in Nature [Nat19].  
Mar 21, 2019
The STEREO experiment releases new results based on the detection of about 65000 neutrinos at short distance from the research reactor of the ILL-Grenoble. The improved accuracy is rejecting the hypothesis of a 4th neutrino in a large fraction of the domain predicted from the reactor neutrino anomaly. Profiting from a good control of the detector response, STEREO now also releases its first absolute measurements of the neutrino rate and the spectrum shape.
Jan 24, 2019
Prediction of nuclear properties based on a realistic description of the strong interaction is at the heart of the ab initio endeavor in low-energy nuclear theory. Ab initio calculations have long been limited to light nuclei or to nuclei with specific proton and neutron numbers. Theoreticians from Irfu/DPhN have developed a new ab initio method from which properties of many more nuclei than before can be predicted while drastically decreasing the computational cost.
Nov 20, 2018
During an experiment carried out at GANIL in Caen (France), an international team, led by researchers from Irfu and the University of Oslo, studied the shape of the Zirconium-98 nucleus. The shape of a nucleus corresponds to the area where its protons and neutrons can be found. Understanding it means mastering the behaviour of each proton/neutron and their arrangement related to the nuclear force. The objective was to determine the shape of the nucleus in different excited states.
Nov 07, 2018
As part of the new CLAS spectrometer project for the 12 GeV electron energy upgrade of the Jefferson Lab (USA) IRFU has been conducting R&D for more than 10 years to design and build a new generation tracker, using thin and flexible MICROMEGAS detectors that are now operating with the new CLAS12 spectrometer. After one year of installation, this tracker is operational and meets the expected characteristics with more than 95% detection efficiency and a spatial resolution of less than 100μm.
Sep 21, 2018
The first triplet of superconducting multipoles of the S3 Super Separator Spectrometer arrived at Ganil on August 29, 2018. S3 is one of the experiment rooms of the Spiral2 facility. The magnet, with a mass of 2.8 tonnes, is 1.8 m long and almost as high. This innovative type of magnet is very compact despite the number of optical functions it can generate (quadrupole, sextupole, octupole and dipole). It is the first of a series of seven to be delivered to the Ganil.
Aug 31, 2018
In an article published in August 2018 in the journal Nature [1], the CLAS collaboration of Jefferson Lab (USA) reports an extensive study on short-range correlations between nucleons in different nuclei. The conclusion goes against intuition, indicating that the greater the ratio of neutrons to protons in a nucleus, the greater the speed of protons relative to neutrons.
Jul 27, 2018
GANIL (Grand accélérateur national d'ions lourds) is carrying out its 2018 experimental campaign from April to July. During the four months of operation, experiments in nuclear physics, atomic physics and materials science will be conducted by research teams from all around the world. Industrial users will also be welcomed at GANIL. During this period, the GANIL accelerators will operate 24 hours a day, 7 days a week.
Jul 27, 2018
NFS (Neutrons For Science) is an experimental area of the Spiral2 facility (Ganil, France) that will provide high intensity neutron beams for energies ranging from 0.5 to 40 MeV. The neutrons will be created by collision of Spiral2 charged particles with carbon, beryllium or lithium targets, thanks to a key element of NFS, the converter. The design of this one is a real challenge because it has to withstand a high power deposited by Spiral2's intense beams.
Jun 04, 2018
An important scientific program is devoted to the three-dimensional structure of the proton in particular its elementary constituents, quarks and gluons. A new generation of experimental facilities at Jefferson Lab (US), CERN, and perhaps later on at a future electron-ion collider (EIC), should make it possible to perform proton tomography with unprecedented accuracy.
May 18, 2018
In ultra-relativistic heavy ion collisions at CERN's LHC accelerator, a new state of matter is formed: the quark-gluon plasma (QGP). It is a kind of very dense and hot "soup" containing only the most elementary constituents of matter. A few microseconds after the Big Bang, the Universe would have passed through this state. Because of the interactions between its constituents, the QGP flows like a fluid.
May 04, 2018
A recent theoretical study of the IRFU has overturned a dark matter mechanism claiming to explain the anomaly in the neutron lifetime. Indeed, the strong constraints, extracted from this mechanism, make it impossible to theoretically predict the neutron stars of 2 solar masses whose existence is known. This study was conducted in collaboration with physicists from the University of Adelaide in Australia, and will soon be published in the journal J. Phys. G.
Mar 27, 2018
The STEREO experiment presented its first physics results at the 53rd Rencontres de Moriond1. STEREO is a neutrino detector made up of six scintillation liquid cells that has been measuring, since November 2016, the electronic antineutrinos produced by the Grenoble high neutron flux reactor 10 metres from the reactor core. The existence of a fourth neutrino state, called sterile neutrino, could explain the deficit in neutrino flux detected at a short distance from nuclear reactors compared to the expected value.
Mar 07, 2018
The T2K collaboration, whose goal is to study and measure neutrino oscillations, is publishing new results on the interaction of neutrinos with nuclei. This study, in which the T2K group of the IRFU plays a major role, is crucial in that it allows the dominant uncertainty on the oscillation parameters to be restrained. For the first time, protons emerging from the neutrino-nucleus interaction have been characterized using new variables capable of exposing and characterizing nuclear effects.
Feb 02, 2018
During an experiment carried out at the accelerator of the Australian National University (Canberra, Australia), a French-Australian collaboration (GANIL Caen, IPN Orsay, IRFU/DPhN Saclay, ANU Canberra) first identified the fragments created in quasi-fission reactions with atomic numbers Z up to plutonium (Z=94) and mass A. For this study, near-fission reactions were induced during collisions between 48Ti projectile ions, accelerated to 276 MeV, and target atoms of 238U.
Dec 20, 2017
The European Committee for Collaboration in Nuclear Physics (NuPECC) published its fifth long-term plan on 19 June. As part of its mission: "to provide advice and make recommendations on the development, organisation and support of European research on nuclear physics and in particular its projects", this plan offers decision-makers and researchers a reference framework for the prospects for the coming years.
Nov 14, 2017
The physicists from the Compass collaboration at Cern, which comprises a team from Irfu, have just published the results of a new measurement of the quark structure of the proton [1]. This uncommon but eagerly awaited measurement tends to confirm one of the basic assumptions of the theory of the strong interaction, the Quantum Chromodynamics (QCD).
Oct 31, 2017
The ScanPyramids collaboration has discovered a new void in the heart of the Kheops pyramid. This large vacuum was detected by muonic imaging techniques conducted by three separate teams from Nagoya University (Japan), CEC (Japan) and CEA/IRFU. It is the first discovery of a major internal structure of Kheops since the Middle Ages.
Jul 18, 2017
To ascertain the "strangeness" property of the proton, an international collaboration including IRFU has produced, starting from protons, other particles containing a "strange" quark and characterized them. These high-precision measurements carried out at CERN in Geneva will lead to a better understanding of the contribution of strange quarks to the nucleon's spin. 
Jun 14, 2017
An international team has performed the first spectroscopy of the very neutron-rich isotopes 98,100 Kr. The collaboration, led by scientists from the CEA Irfu and RIKEN (Japan)  included several European groups and physicists from IPN-Orsay. This experiment showed that there are two coexisting quantum configurations at low excitation energy in the 98Kr nucleus.
Apr 25, 2017
According to the ALICE collaboration at LHC (CERN), certain rare proton collisions have properties that are similar to those of a quark–gluon plasma. In the past, these properties had been observed for collisions of heavy nuclei only. The physicists are now confronted with a new enigma: how can a state of quark–gluon plasma emerge in a system as "small" as that generated by a collision between two protons?

 

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