Feb 08, 2024
Exotic, very neutron-rich nuclei: a laboratory for nuclear interactions
For the first time, an experiment has provided key observations on the spectroscopy of the neutron-rich unbound oxygen nuclei (proton number Z = 8), oxygen 28 (N = 20) and its neighboring isotope at N = 19, oxygen 27.  They were produced in high-energy reactions and observed by direct detection of their decay products, 24O and three or four neutrons.
Jan 25, 2024
ESA's Scientific Program Committee has adopted the LISA mission, giving the go-ahead for construction of the instrument and satellites. For the first time, LISA will observe the Universe through gravitational waves from space.
ISA (Laser Interferometer Space Antenna), the European Space Agency's large-scale mission to explore the Universe by observing the many sources of gravitational waves, was adopted on Thursday January 25 by ESA's Scientific Programs Committee, meaning that the concept and technology are recognized as sufficiently advanced for construction of the instrument and satellites to begin. Launch is scheduled for 2035.
Jan 22, 2024
A comprehensive revision of the summation method lays new and solid foundations for the calculation of antineutrino spectra emitted by a nuclear reactor. This major advance sheds new light on the origin of the reactor antineutrino anomalies, and will be
Supported by CEA's "digital simulation" cross-disciplinary program, Irfu, the Laboratoire National Henri Becquerel of DRT and the Service d'Étude des Réacteurs et de Mathématiques Appliquées of DES teamed up to carry out a thorough review of calculations of antineutrino spectra from nuclear reactors.
Nov 15, 2023
EIC is a future electron-ion collider at Brookhaven National Laboratory (BNL) that will probe the internal structure of nucleons and nuclei with unprecedented precision.
The CEA and the DOE have a long and fruitful collaboration in many fields, including fusion, high-energy physics and nuclear physics, with ongoing projects bringing the two organisations together in these different areas. On Monday 13 November 2023, CEA and DOE signed a “statement of interest” to strengthen their collaboration in accelerator and detector science and technology in preparation for the construction of the Electron-Ion Collider (EIC) based at Brookhaven National Laboratory.  
May 30, 2023
The final piece of a longstanding adventure started in 2014 with an experiment led by Irfu and RIKEN Nishina Center has been set with the publication of a paper containing the comparative study of dineutron correlation in 11Li, 14Be and 17B [1]. This paper published in Phys. Lett. B completes a series of publications on the topic [2,3] issued from the same experiment using the MINOS device designed and built at Irfu. It suggests that such kind of correlations is a universal feature of Borromean halo nuclei.
Apr 13, 2023
Prediction of nuclear properties based on a realistic description of the strong interaction is the main quest of low-energy nuclear theory. One of the issues lies is the cost of solving Schrödinger’s equation that scales exponentially with the number of nucleons. Consequently, theoretical predictions based on first principles have long been limited to very light nuclei, to nuclei with specific proton and neutron numbers offering simplifications or to their ground states.
Jan 23, 2023
Reactor antineutrino anomalies are a decade-long puzzle in neutrino physics. They are manifested by deviations of the order of a few percent between measurements and predictions. These deviations have been observed in the number of antineutrinos measured by more than a dozen experiments at nuclear reactors, and in the shape of the kinetic energy distributions by the seven most recent ones.
Jan 16, 2023
After several years of development at Saclay, the first part of the Falstaff spectrometer was moved to GANIL in 2021 and then installed on NFS for the study of uranium 235. The experiment that took place in November and December 2022 was the first to use an actinide target on SPIRAL2. It demonstrated the good performance of this device.
Jan 12, 2023
The final results of the Stereo experiment have just been published in the journal Nature. A record of precision is established for the spectrum of neutrinos emitted by the fission of 235U, measured between 9 and 11m distance from the ILL reactor core in Grenoble. The hypothesis of a sterile neutrino to explain the reactor neutrino anomaly is rejected. The quality of these direct neutrino measurements now surpasses that of the underlying nuclear data describing the beta decays of fission products.
Dec 13, 2022
Nucleons (protons or neutrons) are the constituents of the nucleus of atoms. The exploration of their internal structure is traditionally done by determining "form factors". These quantities are accessible through the study of elastic electron-proton scattering and electron-positron annihilation reactions into proton-antiproton (or the time reverse reaction of proton-antiproton annihilation into electron-positron).
Nov 07, 2022
A new window into the deformation of nuclei has been recently opened with the realisation that nuclear collision experiments performed at high-energy colliders, such as the BNL Relativistic Heavy Ion Collider (RHIC) or the CERN Large Hadron Collider (LHC), give access to the shape of the colliding isotopes.
Oct 13, 2022
The pygmy dipole resonance (PDR) is a vibrational mode of the nucleus that occurs in neutron-rich nuclei. It is described as the oscillation of a neutron skin against a core symmetric in number of protons and neutrons (Figure 1). The PDR has been the subject of numerous studies, both experimental and theoretical.
Sep 22, 2022
The first measurement of Short-Range Correlations (SRC) in an exotic nucleus took place in May 2022 with the Cocotier instrument at the GSI facility in Darmstadt, Germany. This experiment is a milestone in the program that was started in 2017 with a grant from the French Research Agency that allowed physicists to build a liquid hydrogen target (see previous highlight). The goal of this experiment is to test the hypothesis that nucleon can form compact pair, the so-called SRC pair.
Jun 17, 2022
The DPhN, in collaboration with the Department of Reactor Studies of Cadarache (DES) and the Institute of Particle and Nuclear Physics of Charles University in Prague (Czech Republic), studied the properties of gamma rays emitted by uranium isotopes during neutron capture reactions. Gamma-ray spectra measured at CERN's n_TOF facility were used as a test bed for nuclear reaction models and their ingredients, including the photon strength function that characterises the ability of a nucleus to emit or absorb photons.
Mar 03, 2022
The objective of the realization of efficient compact neutron sources is to make it possible to perform neutron scattering experiments, with practically the same qualities as those carried out with neutron beam lines from research reactors of the Orphée type*. These compact sources are obtained from a protons beam of medium-energy (3-50 MeV) and high current (100 mA) impinging on a light element target as beryllium. This interaction creates a neutron emission.
Jun 24, 2021
DPhN physicists have played a decisive role in the first measurement of pairs of nucleons using a new method, that will pave the way to the study of short range interactions in radioactive nuclei.
Nucleons are social particles. Not only do they enjoy living in communities inside nuclei, but they also form couples within these communities. Indeed, one can observe protons and neutrons forming pairs inside nuclei. DPhN physicists have played a decisive role in the first measurement of such pairs of nucleons using a new method, that will pave the way to the study of these close (or short range) interactions in radioactive nuclei. The results have recently been published in Nature Physics [Pat21].
Jun 04, 2021
Two state-of-the-art instruments, GLAD and COCOTIER, were designed and built at Irfu in the last few years and are now operational in the R3B experimental room of the GSI heavy ion accelerator (Darmstadt, Germany). Both are intended to be part of the equipment that will be used at FAIR, the new machine under construction at the GSI site. GLAD is a large acceptance spectrometer for the analysis of relativistic radioactive heavy ion beam reactions.
May 25, 2021
Since 2010 the question of the size of the proton is at the heart of a controversy between atomic physicists and hadronic physicists. Indeed, very precise measurements of atomic physics have concluded that the size of the proton is much smaller than expected, in very strong disagreement with the experiments of elastic scattering. In collaboration with the University of Perugia, a physicist from IRFU has investigated to find the reason for such a difference.
May 19, 2021
IRFU engineers and physicists and their collaborators have just completed the development of a modern Sirius, a key element of the super spectrometer separator (S3) under construction at GANIL.
The ancients understood that heroes, like Orion with Sirius, need their faithful companion. IRFU engineers and physicists and their collaborators are no exception to the rule and have just completed the development of a modern Sirius, a key element of the super spectrometer separator (S3) under construction at GANIL. The tests having been successful and the system has been moved to GANIL for its final installation.
Apr 14, 2021
Two “mirror” nuclei, in which the numbers of neutrons and protons are interchanged, have markedly different shapes—a finding that defies current nuclear theories. This striking result has been obtained by Irfu researchers in collaboration with an international team and has been recently published in Physics Review Letter [1] and highlighted as editor’s suggestion [2].
Dec 15, 2020
In December 2019, the NFS (Neutrons For Science) facility received its first proton beams, delivered by the linear accelerator of the new Spiral2 facility at the GANIL. On the fringes of the progressive commissioning of the accelerator in 2020, short beam periods were used to successfully test several NFS components. The first experiments are planned at the facility in the fall of 2021.
Dec 08, 2020
In 2016, the announcement of the first direct detection of gravitational waves opened a new window of observation to probe our universe in a new way. The LISA (Laser Interferometer Space Antenna) space observatory promoted by ESA (European Space Agency) will allow the direct detection of gravitational waves undetectable by terrestrial interferometers.
Aug 20, 2020
The spectroscopy of a mendelevium isotope, 251Md composed of 101 protons and 150 neutrons, reveals a surprise: when it rotates, it behaves exactly like a lawrencium isotope made of 103 protons and 152 neutrons. The experiment carried out at the University of Jyväskylä in Finland required the most advanced tools to study these rare and ephemeral nuclei: filtering and identification of the nuclei, gamma ray and electron detection.
Jul 23, 2020
Meteorites are bombarded throughout their journey by cosmic radiation. This cosmic ray exposure (CRE) is a formidable footprint of their history, provided of course that we know how to decipher it. The interaction of cosmic radiation with the atomic nuclei constituting the meteorite will produce so-called cosmogenic isotopes, very often radioactive.
Jul 21, 2020
The combination of the AGATA multi-detector [right] and the VAMOS spectrometer [left] showed that the balance between the two contributions was more complex than previously envisaged.
Jul 02, 2020
The 2020 edition of the Large Hadron Collider Physics Conference (LHCP) took place from 25 to 30 May 2020. Due to the COVID-19 pandemic, the conference, originally planned to be hosted in Paris, was held entirely online.
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.

 

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