Sep 25, 2020

A year and a half after the delivery of the prototype cryomodule (CM00) to ESS, the first production medium beta cryomodule (CM01) has now arrived at the ESS site. It left CEA on September 22, 2020 for a two-day trip to Lund, Sweden. The Irfu teams had previously validated the RF and cryogenic performances of this cryomodule. It will be tested again on the ESS test bench before being integrated in its final position in the accelerator tunnel. This is a first step. Starting next year, ESS will receive an average of one cryomodule per month for 3 years.

 

Jul 15, 2020

In order for the images produced by the future MRI to be free of distortions or artifacts, the magnetic field generated by the Iseult magnet must be homogeneous to 0.5 PPM (parts per million) around the patient's brain. To meet this challenging specification, it was necessary to provision means of "shimming" the field, i.e. of correcting all the small defects that would inevitably arise from the manufacturing process. 5904 pieces of shim (small iron platelets) were screwed onto rails and installed inside the magnet tunnel. This first configuration was tested on Thursday, July 9, 2020 by mapping its effect on the magnetic field of Iseult at 3 T. The results are very encouraging as this first shimming iteration allowed to increase the homogeneity of the field in the useful zone from 138.8 to 3.2 PPM (value extrapolated to 11.72 T from magnetic measurements at 3 T).

May 13, 2020

The EUPRAXIA project has just completed its design study phase with the delivery of the Conceptual Design Report (CDR) at the end of 2019. The strong involvement of IRFU, particularly in the field of particle beam physics, has made it possible to show that solutions exist for the realization of a plasma wakefield accelerator, with a beam quality approaching that of conventional accelerators.
Detailed studies of the physical mechanisms involved have efficiently guided the numerical simulations, each lasting more than 10 hours on 2048 computing nodes, to demonstrate that all the objectives on the output beam can be achieved with a plasma of 30 cm long, 1.1017 cm-3 electronic density and a laser of 400 terawatts power, 50 joules energy. Innovative methods have been developed for accelerating and driving the beam through the two plasma stages to the end user without degrading the beam. A first analysis of error tolerances allowed to identify the most sensitive components to which particular care should be taken during the fabrication and implementation.

Feb 18, 2020

Following SPIRAL2's commissioning authorization issued by the French Nuclear Safety Authority (ASN) on July 8, 2019, many crucial steps were successfully completed by the end of 2019. A first proton beam was accelerated to 33 MeV, the nominal energy by the SPIRAL2 linear accelerator (LINAC) and a first test experiment was achieved the Neutron For Science (NFS) experimental room.


These first results in 2019 are very promising. They will continue in 2020 with the increase in beam power up to 10% of the maximum design power. In parallel test experiments in NFS will be carried out.

 

Sep 15, 2020

Thanks to the GANIL accelerated heavy ion collisions and the detection of reaction products with the INDRA detector, it was possible to deduce the evolution parameters of chemical elements in stellar phenomena. 

 

These chemical elements, light nuclei (d, t, 3He, α, 6He…), are created by aggregation of protons and neutrons during the collision between the projectile nucleus and the target nucleus. The measurement with INDRA has shown that their production rate is higher than the rate expected by the ideal gas model. The work of the INDRA collaboration, with the help of three theorists, consisted in performing a Bayesian analysis on the data to extract the thermodynamic observables taking into account the effects of the nuclear matter environment and then comparing the data thus obtained with a model. 
This result is important since it measures the chemical concentration of aggregates in areas of low nuclear density, the same densities found in nuclear collapse supernovae. The process of this stellar event is largely dominated by the emission of neutrinos that can be captured by free neutrons or present in the aggregates. Thus the chemical concentration of these elements determines the neutrino transport and thus the evolution of the supernova.

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.                                           

The complexity of the atomic nucleus reflects a multi-component character of the « nuclear force » that holds protons and neutrons together. Proper separation and characterization of each of these components represents a challenge for both theoretical and experimental nuclear structure studies. The tin isotopes (nuclei with Z=50 protons and a number of neutrons depending on the isotope) provide ideal opportunities to study the competition between two of the nuclear force components: the so-called pairing, related to the marked tendency of protons and neutrons to form pairs in the nuclear matter, and the so-called quadrupole interaction term, describing the natural susceptibility of nuclei to adopt deformed shapes. Though of a different nature, these two interaction terms contribute to the goal of achieving an optimum organization of nucleons in the atomic nucleus that will minimize its energy.  Previous works have demonstrated that a shift of balance between these two components takes place when approaching tin-100, and this observation provided important constraints for theoretical descriptions of this so-called “doubly-magic” nucleus. Having the same numbers of protons and neutrons (Z=N=50), 100Sn is a key nucleus to validate model descriptions of exotic nuclei.

Jun 17, 2020

GANIL hosted the annual IPAC conference in GANIL but not physically in Caen but “virtually” (due the pandemic conditions).

This first virtual conference was “attended ” by 3000 people from the world wide accelerator community, representing around 300 institutions/laboratories.

The conference consisted of 77 prerecorded talks lasting around 25 hours and two sessions, the awards and the closing ceremony were broadcast live.

A summary of statistics can be accessed here.

The grand success of this first virtual IPAC will serve as a gold standard for such future conferences.

The following edition of this annual conference will be held in Brazil, Thailand, Italy and USA.

L'article de Cerncourrier: IPAC goes virtual

Sep 25, 2020

A year and a half after the delivery of the prototype cryomodule (CM00) to ESS, the first production medium beta cryomodule (CM01) has now arrived at the ESS site. It left CEA on September 22, 2020 for a two-day trip to Lund, Sweden. The Irfu teams had previously validated the RF and cryogenic performances of this cryomodule. It will be tested again on the ESS test bench before being integrated in its final position in the accelerator tunnel. This is a first step. Starting next year, ESS will receive an average of one cryomodule per month for 3 years.

 

Sep 15, 2020

Thanks to the GANIL accelerated heavy ion collisions and the detection of reaction products with the INDRA detector, it was possible to deduce the evolution parameters of chemical elements in stellar phenomena. 

 

These chemical elements, light nuclei (d, t, 3He, α, 6He…), are created by aggregation of protons and neutrons during the collision between the projectile nucleus and the target nucleus. The measurement with INDRA has shown that their production rate is higher than the rate expected by the ideal gas model. The work of the INDRA collaboration, with the help of three theorists, consisted in performing a Bayesian analysis on the data to extract the thermodynamic observables taking into account the effects of the nuclear matter environment and then comparing the data thus obtained with a model. 
This result is important since it measures the chemical concentration of aggregates in areas of low nuclear density, the same densities found in nuclear collapse supernovae. The process of this stellar event is largely dominated by the emission of neutrinos that can be captured by free neutrons or present in the aggregates. Thus the chemical concentration of these elements determines the neutrino transport and thus the evolution of the supernova.

Aug 07, 2020

In 2019, a first muon tomography had been carried out from several 2D projections, via a collaboration with the University of Florence. The limitations remained numerous, however, because the imaged object was only about twenty centimeters, with very high density contrasts (Lead bricks), and only one fixed telescope operating in the very particular mode of absorption. One by one, all these limitations were removed through a complete redesign of the algorithms and optimization of the computing times. It is now possible to reconstruct the 3D structure of structures longer than 100 meters, with realistic density variations and any number of telescopes operating in the most general mode of transmission. As an illustration, the number of matrix elements of the system to be solved has thus increased from about 10 million for the 2019 version to more than 20 trillion today.

Aug 03, 2020

Photon-photon elastic scattering is a very rare phenomenon in which two real photons interact producing a new real photon pair. The direct observation of this process at high energy, impossible during decades, was done by ATLAS [1] and CMS [2] experiment at CERN between 2016 and 2019. These successes have led the two collaborations to strengthen their involvement in this new field, leading to a new measurement, currently being published by the ATLAS experiment [3]. Presented for the first time at the LHCP conference in May 2020, the new idea is to use photon collisions to search for a hypothetical axion-like particle. As with the first publications on the subject, IRFU members are at the origin of the ideas at work in the analyses carried out at CERN.

Jul 28, 2020
Link between magnetars and Fast radio bursts

An international campaign including ground-based and space telescopes, including the INTEGRAL satellite, discovered end of April 2020 very short pulses in both X-rays and radio waves coming from a compact object in the Galaxy, the magnetar SGR 1935+2154. The simultaneous observation of these signals is seen for the first time in this type of source and attests a connection between magnetars and Fast radio bursts, a class of radio sources whose origin is today poorly known. This work, that includes researchers from the Astrophysics Department/ AIM Laboratory of CEA-Irfu of Paris-Saclay, is published in The Astrophysical Journal Letters and subject press release of a European Space Agency (ESA).

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.                                           

The complexity of the atomic nucleus reflects a multi-component character of the « nuclear force » that holds protons and neutrons together. Proper separation and characterization of each of these components represents a challenge for both theoretical and experimental nuclear structure studies. The tin isotopes (nuclei with Z=50 protons and a number of neutrons depending on the isotope) provide ideal opportunities to study the competition between two of the nuclear force components: the so-called pairing, related to the marked tendency of protons and neutrons to form pairs in the nuclear matter, and the so-called quadrupole interaction term, describing the natural susceptibility of nuclei to adopt deformed shapes. Though of a different nature, these two interaction terms contribute to the goal of achieving an optimum organization of nucleons in the atomic nucleus that will minimize its energy.  Previous works have demonstrated that a shift of balance between these two components takes place when approaching tin-100, and this observation provided important constraints for theoretical descriptions of this so-called “doubly-magic” nucleus. Having the same numbers of protons and neutrons (Z=N=50), 100Sn is a key nucleus to validate model descriptions of exotic nuclei.

Jul 20, 2020

The Sloan Digital Sky Survey (SDSS) published in July a complete analysis of the largest three-dimensional map of the Universe ever created, reconstructing the history of its expansion over a period of 11 billion years.

Jul 15, 2020

In order for the images produced by the future MRI to be free of distortions or artifacts, the magnetic field generated by the Iseult magnet must be homogeneous to 0.5 PPM (parts per million) around the patient's brain. To meet this challenging specification, it was necessary to provision means of "shimming" the field, i.e. of correcting all the small defects that would inevitably arise from the manufacturing process. 5904 pieces of shim (small iron platelets) were screwed onto rails and installed inside the magnet tunnel. This first configuration was tested on Thursday, July 9, 2020 by mapping its effect on the magnetic field of Iseult at 3 T. The results are very encouraging as this first shimming iteration allowed to increase the homogeneity of the field in the useful zone from 138.8 to 3.2 PPM (value extrapolated to 11.72 T from magnetic measurements at 3 T).

Jul 11, 2020

That's one wall the White Walkers won't cross. An international collaboration bringing together the IRFU (Université Paris-Saclay), the Astronomy Institute of the University of Hawaii, the LPC (Université Clermont Auvergne), the IP2I (Université Claude Bernard de Lyon), and the Racah Institute of Physics (Hebrew University of Jerusalem), has discovered an immense structure in the distribution of galaxies, called the "South Pole Wall".

Thanks to a method based on the velocity fields of galaxies, this region of the sky, previously unknown because it is masked by molecular clouds and dust located in the foreground of our galaxy, brings a new piece to the puzzle of the cosmic web of our nearby Universe. This cosmic web consists of nodes connected by filaments, separating voids. Galaxies are pulled from the voids to the filaments and then to the gravitational attractors located at the nodes of the web. The filaments, sandwiched between the voids, can take a flattened shape to form walls.

The South Pole Wall has a huge rectilinear section (220 Mpc) at the ends of which it curves to follow the Laniakea border.

These works are published in APJ journal https://doi.org/10.3847/1538-4357/ab9952

Jul 08, 2020

Scientists from the large cosmological survey SDSS/eBOSS have constructed the first so-called "tomographic" map of the far Universe on a very large scale, which until now only existed in one dimension, along the line of sight of the ground-based telescope. To do this, they used the latest Lyman-alpha forest data, which indirectly plot the density of matter in the direction of bright objects, the quasars. The resulting map covers a cube of 3.26 billion light-years from observations of nearly 10,000 quasars. It is a new tool for studying the history of the Universe and its structures.


This work is published in the JCAP journal (arXiv:2004.01448).

 

Jun 28, 2020

In its standard form, double beta decay is a process in which a nucleus decays into a different nucleus and emits two electrons and two antineutrinos (2νββ). This nuclear transition is very rare, but it was detected in several nuclei with sophisticated experiments. If neutrinos are their own antiparticles, it’s possible that the antineutrinos emitted during double beta decay annihilate one another and disappear. This is called neutrinoless double beta decay (0νββ), a phenomenon never observed so far. If 0νββ is detected, we will ascertain that neutrinos are their own antiparticles, and this would be a clue as to why they get their tiny masses—and whether they played a part in the existence of our matter-dominated universe. 

The CUPID-Mo experiment, installed at the Modane Underground Laboratory, after one year of data between March 2019 and April 2020 has just set a new global limit for the detection of the signature 0νββ.

Jun 17, 2020

GANIL hosted the annual IPAC conference in GANIL but not physically in Caen but “virtually” (due the pandemic conditions).

This first virtual conference was “attended ” by 3000 people from the world wide accelerator community, representing around 300 institutions/laboratories.

The conference consisted of 77 prerecorded talks lasting around 25 hours and two sessions, the awards and the closing ceremony were broadcast live.

A summary of statistics can be accessed here.

The grand success of this first virtual IPAC will serve as a gold standard for such future conferences.

The following edition of this annual conference will be held in Brazil, Thailand, Italy and USA.

L'article de Cerncourrier: IPAC goes virtual

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. In order to limit as far as possible the amount of material crossed by the particles, the conception of this detector has required the development of many innovative techniques and procedures, particularly in the integration of silicon sensors on flexible hybrid circuits called ladders, for which Irfu was responsible within the project. It took two years to manufacture the 500 ladders of the MFT, and a very long sequence of operations was the subject of numerous studies under the responsibility of the Irfu Antenna team at CERN. The production of these ladders has just been successfully completed and it is therefore time to make a short assessment

Jun 04, 2020

On May 18th 2020, ESO formally closed the preliminary design review of the ELT/METIS thermal infrared instrument. Following this important milestone, the instrument enters into the final design phase (phase C) in which the its design will be frozen just before its building.

Jun 02, 2020
VLT/SPHERE observations of the star AB Aurigae pinpoint a giant planet in formation

Motivated by unusual features recently observed with the ALMA instrument in a proto-planetary disc around the star AB Aurigae, an international team of astrophysicists including a researcher from the Department of Astrophysics / Laboratory AIM of the CEA-Irfu of Paris-Saclay has just obtained a very sharp high-contrast image of a S-shasped sub-structure in the gaseous and dusty disc surrounding the star. This remarkable structure, unique and captured thanks to the excellent image quality of the ESO VLT SPHERE instrument, indicates the presence of a giant planet in formation, confirming a theoretical scenario of the birth of planets. Published in the journal Astronomy and Astrophysics, and subject of an ESO announcement, this work is a precursor to future research programmes on protoplanetary disks with the future ELT/METIS instrument.

May 29, 2020

The simple question “Where does the Periodic Table end?” has excited scientific interest for a long time. In this context, understanding the structure of the heaviest nuclei, and through it their stability, is of major importance. A decade ago, there was no promising path to tackle this scientific quest. And yet, in the past few years, a collaboration composed of physicists coming from Irfu/DPhN, Jyvaskyla (Finland), GSI (Germany) and Argonne (USA) applied a newly developed technique relying on high performance accelerators and state-of-the-art detectors to investigate the isomeric (long-lived) states in heavy nuclei[KS1] [2] . It has triggered a renaissance in heavy ion elements science. New focal plane detectors equipped with digital electronics has been for the first time extended to short-lived states[KS3]  in heavy nuclei, allowing the detection of very close events and very short half-life (few µs). This opens new perspectives as  to date, the heaviest element found is Oganesson with a half-life of 0.58ms.The results have been published in the Physical review C [1].

 

May 20, 2020
The fourth catalog of Fermi-LAT sources comes on line

The Fermi-LAT collaboration has published its fourth source catalog, named 4FGL. Based on eight years of data, it contains 5064 celestial objects emitting gamma rays at energies around 1 GeV, adding more than 2000 high-energy sources to the previous collection (published in 2015). More than one fourth of the objects are of unknown nature, calling for numerous follow-up studies. Although its volume is modest compared to the billions of sources listed in optical catalogs, the 4FGL catalog is by far the deepest in gamma-ray astronomy and serves as a reference to the entire domain. The catalog, coordinated by a researcher at the Astrophysics Department (AIM Laboratory) of CEA-Irfu at Paris-Saclay, is accessible on line at the NASA Fermi web site. In parallel, the 4LAC census of active galactic nuclei (coordinated by a researcher at CNRS/CENBG) is also made available to the community.

May 13, 2020

The EUPRAXIA project has just completed its design study phase with the delivery of the Conceptual Design Report (CDR) at the end of 2019. The strong involvement of IRFU, particularly in the field of particle beam physics, has made it possible to show that solutions exist for the realization of a plasma wakefield accelerator, with a beam quality approaching that of conventional accelerators.
Detailed studies of the physical mechanisms involved have efficiently guided the numerical simulations, each lasting more than 10 hours on 2048 computing nodes, to demonstrate that all the objectives on the output beam can be achieved with a plasma of 30 cm long, 1.1017 cm-3 electronic density and a laser of 400 terawatts power, 50 joules energy. Innovative methods have been developed for accelerating and driving the beam through the two plasma stages to the end user without degrading the beam. A first analysis of error tolerances allowed to identify the most sensitive components to which particular care should be taken during the fabrication and implementation.

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. Therefore, for a better understanding of the strong interaction, it may be interesting to measure the polarization of the particles produced in a nuclear reaction. The devices to measure the polarization are called polarimeters. Conceiving, building, testing and validating polarimeters requires proton and neutron polarized beams, of known polarization. Today, such beams of energy in the GeV range are available only at the Nuclotron complex of JINR, Dubna, in Russia. In order to optimize neutron and proton polarimetry at energies of few GeV, analyzing powers have been measured with Nuclotron beams on different targets: Carbone, mylar, paraffine, as well as on a heavier target, cupper, for beam momenta in the range 3 – 4.2 GeV/c. The present work indicates that high-energy polarimetry shows specific characteristics, opening the way to innovative experimental approaches. These results have been published in EPJA, as ‘Special article’, section ‘New Tools and Methods’ [1].

Apr 15, 2020

We live in a world of matter – because matter overtook antimatter, though they were both created in equal amounts by the Big Bang when our universe began. As featured on the cover of Nature on 16 April 2020, neutrinos and the associated antimatter particles, antineutrinos, are reported to have a high likelihood of differing behaviour that offers a promising path to explaining the asymmetry between matter and antimatter. These observations may explain this mysterious antimatter disappearance. They come from the T2K experiment conducted in Japan and in which three French laboratories are involved, affiliated with the CNRS, the École Polytechnique - Institut Polytechnique de Paris, the Sorbonne Université and the CEA.

Mar 13, 2020
The highest magnetic fileds of the Universe reproduced by numerical simulations

Magnetars are neutron stars endowed with the strongest magnetic fields observed in the Universe, but their origin remains controversial. In a study published in Science Advances, a team of scientists from the Astrophysics Division at CEA-IRFU / AIM Laboratory and collaborators from the Max Planck Institute and the Institut de Physique du Globe de Paris developed a new and unprecedentedly detailed computer model that can explain the genesis of these gigantic fields through the amplification of pre-existing weak fields when rapidly rotating neutron stars are born in collapsing massive stars. The work opens new avenues to understand the most powerful and most luminous explosions of such stars.

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. This work was at the heart of a recently defended thesis (2019) and the new possibilities offered by this code were published in early 2020 in the journal Physical Review C [1].
 

Feb 18, 2020

Following SPIRAL2's commissioning authorization issued by the French Nuclear Safety Authority (ASN) on July 8, 2019, many crucial steps were successfully completed by the end of 2019. A first proton beam was accelerated to 33 MeV, the nominal energy by the SPIRAL2 linear accelerator (LINAC) and a first test experiment was achieved the Neutron For Science (NFS) experimental room.


These first results in 2019 are very promising. They will continue in 2020 with the increase in beam power up to 10% of the maximum design power. In parallel test experiments in NFS will be carried out.

 

Feb 13, 2020

To measure cosmological parameters, the Euclid space telescope will use two main probes: gravitational lensing (Weak Gravitational Lensing) and galaxy distribution (Galaxy Clustering). These measurements will allow us to study dark energy and dark matter, which affect the growth of cosmic structures and the accelerated expansion of the Universe.

In addition to its implications on instrumental developments and data processing, Irfu is actively involved in the development of algorithms needed to prepare the extraction of cosmological parameters that will be derived from Euclid measurements.

Coordinated by Valeria Pettorino, physicist at Irfu's CosmoStat laboratory, in collaboration with Tom Kitching (UCL[1]) and Ariel Sanchez (MPE[2]), an international team from the Euclid collaboration with complementary expertise in theory and observation has just completed a 3-year study characterizing the performances expected from Euclid for these observational probes.


Publication an Arxiv: https://arxiv.org/pdf/1910.09273.pdf


[1] University College London ; [2] Max Planck Institute for extraterrestrial physics
Jan 23, 2020

Arrived safely. The focal plane of the visible imager on the Euclid satellite has just been delivered by Irfu to the laboratory responsible for the instrument (MSSL/UK) to continue its integration into the satellite, which is scheduled to take off in 2022. 

The first studies of this focal plane have been carried out at Irfu since 2010 and after almost 10 years of development and testing, it was fully tested by Irfu in 2019. This Focal Plane is composed of 36 CDDs totalizing more than 600 million pixels. Each image acquired in flight by this focal plane will make it possible to characterize more than 50,000 galaxies. It is the second largest camera, observing in the visible, launched into space after that of the Gaïa satellite. In space, its observations will allow the measurement of galaxy deformations due to weak gravitational lensing effects induced by clusters of dark matter that light encounters on its way to us. These gravitational distortion effects measured at different ages of the Universe will provide measurements of the distribution of dark matter and will be a constraint on dark energy.

*Mullard Space Science Laboratory

Jan 17, 2020

A few microseconds after the Big Bang the Univers may have gone through a deconfined state of quarks and gluons, the Quark–Gluon Plasma (QGP). The QGP can be recreated in high-energy heavy-ion collisions. In particular at the LHC at CERN, the QGP behaves like a fluid. All particles, light, strange, or charmed flow collectively as if being carried by the same fluid, proving the strength of the interactions between QGP constituents. The ALICE Collaboration at the LHC, with decisive contributions from the Irfu teams, has just published, in the prestigious Physical Review Letters journal, the first measurement of the elliptic flow of Υ(1S) (a particle composed of a beauty quark and its antiquark). This resonance appears as the first particle at the LHC not flowing with the fluid. This pioneering result opens up the path for deeper studies of the QGP.

Jan 13, 2020
A collision of the Milky Way with a small galaxy accurately dated by the study of the star ν Indi

ν Indi is a bright star (visual magnitude mv = 5.3) visible with the naked-eye from the southern hemisphere. By using ground data (ESO telescopes), space data (Gaia and Tess missions) and by combining very diverse spectroscopic, astrometric, kinematic or asteroseismological information, an international team including two researchers from the Department of Astrophysics / AIM Laboratory of CEA-Saclay was able to determine the epoch, between 11.6 and 13.2 billion years ago, of a collision between our galaxy and a small dwarf galaxy, Gaia-Enceladus. This work is published in the journal Nature Astronomy, January 2020.

Jan 08, 2020

The international CUPID-Mo experiment conducted by French laboratories of IN2P3, CEA/IRFU and CEA/IRAMIS has been testing the use of Molybdenum-based crystals since last April to detect double beta decay without neutrino emission. The experiment is gradually gaining strength and already shows a near-zero background in the region of interest, which is very promising. The scientists of the collaboration made an update in the occasion of the official inauguration on 11 and 12 December 2019.

Jul 28, 2020
Link between magnetars and Fast radio bursts

An international campaign including ground-based and space telescopes, including the INTEGRAL satellite, discovered end of April 2020 very short pulses in both X-rays and radio waves coming from a compact object in the Galaxy, the magnetar SGR 1935+2154. The simultaneous observation of these signals is seen for the first time in this type of source and attests a connection between magnetars and Fast radio bursts, a class of radio sources whose origin is today poorly known. This work, that includes researchers from the Astrophysics Department/ AIM Laboratory of CEA-Irfu of Paris-Saclay, is published in The Astrophysical Journal Letters and subject press release of a European Space Agency (ESA).

Jun 04, 2020

On May 18th 2020, ESO formally closed the preliminary design review of the ELT/METIS thermal infrared instrument. Following this important milestone, the instrument enters into the final design phase (phase C) in which the its design will be frozen just before its building.

Jun 02, 2020
VLT/SPHERE observations of the star AB Aurigae pinpoint a giant planet in formation

Motivated by unusual features recently observed with the ALMA instrument in a proto-planetary disc around the star AB Aurigae, an international team of astrophysicists including a researcher from the Department of Astrophysics / Laboratory AIM of the CEA-Irfu of Paris-Saclay has just obtained a very sharp high-contrast image of a S-shasped sub-structure in the gaseous and dusty disc surrounding the star. This remarkable structure, unique and captured thanks to the excellent image quality of the ESO VLT SPHERE instrument, indicates the presence of a giant planet in formation, confirming a theoretical scenario of the birth of planets. Published in the journal Astronomy and Astrophysics, and subject of an ESO announcement, this work is a precursor to future research programmes on protoplanetary disks with the future ELT/METIS instrument.

May 20, 2020
The fourth catalog of Fermi-LAT sources comes on line

The Fermi-LAT collaboration has published its fourth source catalog, named 4FGL. Based on eight years of data, it contains 5064 celestial objects emitting gamma rays at energies around 1 GeV, adding more than 2000 high-energy sources to the previous collection (published in 2015). More than one fourth of the objects are of unknown nature, calling for numerous follow-up studies. Although its volume is modest compared to the billions of sources listed in optical catalogs, the 4FGL catalog is by far the deepest in gamma-ray astronomy and serves as a reference to the entire domain. The catalog, coordinated by a researcher at the Astrophysics Department (AIM Laboratory) of CEA-Irfu at Paris-Saclay, is accessible on line at the NASA Fermi web site. In parallel, the 4LAC census of active galactic nuclei (coordinated by a researcher at CNRS/CENBG) is also made available to the community.

Mar 13, 2020
The highest magnetic fileds of the Universe reproduced by numerical simulations

Magnetars are neutron stars endowed with the strongest magnetic fields observed in the Universe, but their origin remains controversial. In a study published in Science Advances, a team of scientists from the Astrophysics Division at CEA-IRFU / AIM Laboratory and collaborators from the Max Planck Institute and the Institut de Physique du Globe de Paris developed a new and unprecedentedly detailed computer model that can explain the genesis of these gigantic fields through the amplification of pre-existing weak fields when rapidly rotating neutron stars are born in collapsing massive stars. The work opens new avenues to understand the most powerful and most luminous explosions of such stars.

Feb 13, 2020

To measure cosmological parameters, the Euclid space telescope will use two main probes: gravitational lensing (Weak Gravitational Lensing) and galaxy distribution (Galaxy Clustering). These measurements will allow us to study dark energy and dark matter, which affect the growth of cosmic structures and the accelerated expansion of the Universe.

In addition to its implications on instrumental developments and data processing, Irfu is actively involved in the development of algorithms needed to prepare the extraction of cosmological parameters that will be derived from Euclid measurements.

Coordinated by Valeria Pettorino, physicist at Irfu's CosmoStat laboratory, in collaboration with Tom Kitching (UCL[1]) and Ariel Sanchez (MPE[2]), an international team from the Euclid collaboration with complementary expertise in theory and observation has just completed a 3-year study characterizing the performances expected from Euclid for these observational probes.


Publication an Arxiv: https://arxiv.org/pdf/1910.09273.pdf


[1] University College London ; [2] Max Planck Institute for extraterrestrial physics
Jan 23, 2020

Arrived safely. The focal plane of the visible imager on the Euclid satellite has just been delivered by Irfu to the laboratory responsible for the instrument (MSSL/UK) to continue its integration into the satellite, which is scheduled to take off in 2022. 

The first studies of this focal plane have been carried out at Irfu since 2010 and after almost 10 years of development and testing, it was fully tested by Irfu in 2019. This Focal Plane is composed of 36 CDDs totalizing more than 600 million pixels. Each image acquired in flight by this focal plane will make it possible to characterize more than 50,000 galaxies. It is the second largest camera, observing in the visible, launched into space after that of the Gaïa satellite. In space, its observations will allow the measurement of galaxy deformations due to weak gravitational lensing effects induced by clusters of dark matter that light encounters on its way to us. These gravitational distortion effects measured at different ages of the Universe will provide measurements of the distribution of dark matter and will be a constraint on dark energy.

*Mullard Space Science Laboratory

Jan 13, 2020
A collision of the Milky Way with a small galaxy accurately dated by the study of the star ν Indi

ν Indi is a bright star (visual magnitude mv = 5.3) visible with the naked-eye from the southern hemisphere. By using ground data (ESO telescopes), space data (Gaia and Tess missions) and by combining very diverse spectroscopic, astrometric, kinematic or asteroseismological information, an international team including two researchers from the Department of Astrophysics / AIM Laboratory of CEA-Saclay was able to determine the epoch, between 11.6 and 13.2 billion years ago, of a collision between our galaxy and a small dwarf galaxy, Gaia-Enceladus. This work is published in the journal Nature Astronomy, January 2020.

Sep 25, 2020

A year and a half after the delivery of the prototype cryomodule (CM00) to ESS, the first production medium beta cryomodule (CM01) has now arrived at the ESS site. It left CEA on September 22, 2020 for a two-day trip to Lund, Sweden. The Irfu teams had previously validated the RF and cryogenic performances of this cryomodule. It will be tested again on the ESS test bench before being integrated in its final position in the accelerator tunnel. This is a first step. Starting next year, ESS will receive an average of one cryomodule per month for 3 years.

 

Jul 11, 2020

That's one wall the White Walkers won't cross. An international collaboration bringing together the IRFU (Université Paris-Saclay), the Astronomy Institute of the University of Hawaii, the LPC (Université Clermont Auvergne), the IP2I (Université Claude Bernard de Lyon), and the Racah Institute of Physics (Hebrew University of Jerusalem), has discovered an immense structure in the distribution of galaxies, called the "South Pole Wall".

Thanks to a method based on the velocity fields of galaxies, this region of the sky, previously unknown because it is masked by molecular clouds and dust located in the foreground of our galaxy, brings a new piece to the puzzle of the cosmic web of our nearby Universe. This cosmic web consists of nodes connected by filaments, separating voids. Galaxies are pulled from the voids to the filaments and then to the gravitational attractors located at the nodes of the web. The filaments, sandwiched between the voids, can take a flattened shape to form walls.

The South Pole Wall has a huge rectilinear section (220 Mpc) at the ends of which it curves to follow the Laniakea border.

These works are published in APJ journal https://doi.org/10.3847/1538-4357/ab9952

Jul 08, 2020

Scientists from the large cosmological survey SDSS/eBOSS have constructed the first so-called "tomographic" map of the far Universe on a very large scale, which until now only existed in one dimension, along the line of sight of the ground-based telescope. To do this, they used the latest Lyman-alpha forest data, which indirectly plot the density of matter in the direction of bright objects, the quasars. The resulting map covers a cube of 3.26 billion light-years from observations of nearly 10,000 quasars. It is a new tool for studying the history of the Universe and its structures.


This work is published in the JCAP journal (arXiv:2004.01448).

 

Jun 28, 2020

In its standard form, double beta decay is a process in which a nucleus decays into a different nucleus and emits two electrons and two antineutrinos (2νββ). This nuclear transition is very rare, but it was detected in several nuclei with sophisticated experiments. If neutrinos are their own antiparticles, it’s possible that the antineutrinos emitted during double beta decay annihilate one another and disappear. This is called neutrinoless double beta decay (0νββ), a phenomenon never observed so far. If 0νββ is detected, we will ascertain that neutrinos are their own antiparticles, and this would be a clue as to why they get their tiny masses—and whether they played a part in the existence of our matter-dominated universe. 

The CUPID-Mo experiment, installed at the Modane Underground Laboratory, after one year of data between March 2019 and April 2020 has just set a new global limit for the detection of the signature 0νββ.

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. In order to limit as far as possible the amount of material crossed by the particles, the conception of this detector has required the development of many innovative techniques and procedures, particularly in the integration of silicon sensors on flexible hybrid circuits called ladders, for which Irfu was responsible within the project. It took two years to manufacture the 500 ladders of the MFT, and a very long sequence of operations was the subject of numerous studies under the responsibility of the Irfu Antenna team at CERN. The production of these ladders has just been successfully completed and it is therefore time to make a short assessment

Feb 18, 2020

Following SPIRAL2's commissioning authorization issued by the French Nuclear Safety Authority (ASN) on July 8, 2019, many crucial steps were successfully completed by the end of 2019. A first proton beam was accelerated to 33 MeV, the nominal energy by the SPIRAL2 linear accelerator (LINAC) and a first test experiment was achieved the Neutron For Science (NFS) experimental room.


These first results in 2019 are very promising. They will continue in 2020 with the increase in beam power up to 10% of the maximum design power. In parallel test experiments in NFS will be carried out.

 

Jan 23, 2020

Arrived safely. The focal plane of the visible imager on the Euclid satellite has just been delivered by Irfu to the laboratory responsible for the instrument (MSSL/UK) to continue its integration into the satellite, which is scheduled to take off in 2022. 

The first studies of this focal plane have been carried out at Irfu since 2010 and after almost 10 years of development and testing, it was fully tested by Irfu in 2019. This Focal Plane is composed of 36 CDDs totalizing more than 600 million pixels. Each image acquired in flight by this focal plane will make it possible to characterize more than 50,000 galaxies. It is the second largest camera, observing in the visible, launched into space after that of the Gaïa satellite. In space, its observations will allow the measurement of galaxy deformations due to weak gravitational lensing effects induced by clusters of dark matter that light encounters on its way to us. These gravitational distortion effects measured at different ages of the Universe will provide measurements of the distribution of dark matter and will be a constraint on dark energy.

*Mullard Space Science Laboratory

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.                                           

The complexity of the atomic nucleus reflects a multi-component character of the « nuclear force » that holds protons and neutrons together. Proper separation and characterization of each of these components represents a challenge for both theoretical and experimental nuclear structure studies. The tin isotopes (nuclei with Z=50 protons and a number of neutrons depending on the isotope) provide ideal opportunities to study the competition between two of the nuclear force components: the so-called pairing, related to the marked tendency of protons and neutrons to form pairs in the nuclear matter, and the so-called quadrupole interaction term, describing the natural susceptibility of nuclei to adopt deformed shapes. Though of a different nature, these two interaction terms contribute to the goal of achieving an optimum organization of nucleons in the atomic nucleus that will minimize its energy.  Previous works have demonstrated that a shift of balance between these two components takes place when approaching tin-100, and this observation provided important constraints for theoretical descriptions of this so-called “doubly-magic” nucleus. Having the same numbers of protons and neutrons (Z=N=50), 100Sn is a key nucleus to validate model descriptions of exotic nuclei.

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. In order to limit as far as possible the amount of material crossed by the particles, the conception of this detector has required the development of many innovative techniques and procedures, particularly in the integration of silicon sensors on flexible hybrid circuits called ladders, for which Irfu was responsible within the project. It took two years to manufacture the 500 ladders of the MFT, and a very long sequence of operations was the subject of numerous studies under the responsibility of the Irfu Antenna team at CERN. The production of these ladders has just been successfully completed and it is therefore time to make a short assessment

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. Therefore, for a better understanding of the strong interaction, it may be interesting to measure the polarization of the particles produced in a nuclear reaction. The devices to measure the polarization are called polarimeters. Conceiving, building, testing and validating polarimeters requires proton and neutron polarized beams, of known polarization. Today, such beams of energy in the GeV range are available only at the Nuclotron complex of JINR, Dubna, in Russia. In order to optimize neutron and proton polarimetry at energies of few GeV, analyzing powers have been measured with Nuclotron beams on different targets: Carbone, mylar, paraffine, as well as on a heavier target, cupper, for beam momenta in the range 3 – 4.2 GeV/c. The present work indicates that high-energy polarimetry shows specific characteristics, opening the way to innovative experimental approaches. These results have been published in EPJA, as ‘Special article’, section ‘New Tools and Methods’ [1].

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. This work was at the heart of a recently defended thesis (2019) and the new possibilities offered by this code were published in early 2020 in the journal Physical Review C [1].
 

Aug 03, 2020

Photon-photon elastic scattering is a very rare phenomenon in which two real photons interact producing a new real photon pair. The direct observation of this process at high energy, impossible during decades, was done by ATLAS [1] and CMS [2] experiment at CERN between 2016 and 2019. These successes have led the two collaborations to strengthen their involvement in this new field, leading to a new measurement, currently being published by the ATLAS experiment [3]. Presented for the first time at the LHCP conference in May 2020, the new idea is to use photon collisions to search for a hypothetical axion-like particle. As with the first publications on the subject, IRFU members are at the origin of the ideas at work in the analyses carried out at CERN.

Jul 20, 2020

The Sloan Digital Sky Survey (SDSS) published in July a complete analysis of the largest three-dimensional map of the Universe ever created, reconstructing the history of its expansion over a period of 11 billion years.

Jul 08, 2020

Scientists from the large cosmological survey SDSS/eBOSS have constructed the first so-called "tomographic" map of the far Universe on a very large scale, which until now only existed in one dimension, along the line of sight of the ground-based telescope. To do this, they used the latest Lyman-alpha forest data, which indirectly plot the density of matter in the direction of bright objects, the quasars. The resulting map covers a cube of 3.26 billion light-years from observations of nearly 10,000 quasars. It is a new tool for studying the history of the Universe and its structures.


This work is published in the JCAP journal (arXiv:2004.01448).

 

Jun 28, 2020

In its standard form, double beta decay is a process in which a nucleus decays into a different nucleus and emits two electrons and two antineutrinos (2νββ). This nuclear transition is very rare, but it was detected in several nuclei with sophisticated experiments. If neutrinos are their own antiparticles, it’s possible that the antineutrinos emitted during double beta decay annihilate one another and disappear. This is called neutrinoless double beta decay (0νββ), a phenomenon never observed so far. If 0νββ is detected, we will ascertain that neutrinos are their own antiparticles, and this would be a clue as to why they get their tiny masses—and whether they played a part in the existence of our matter-dominated universe. 

The CUPID-Mo experiment, installed at the Modane Underground Laboratory, after one year of data between March 2019 and April 2020 has just set a new global limit for the detection of the signature 0νββ.

Jan 08, 2020

The international CUPID-Mo experiment conducted by French laboratories of IN2P3, CEA/IRFU and CEA/IRAMIS has been testing the use of Molybdenum-based crystals since last April to detect double beta decay without neutrino emission. The experiment is gradually gaining strength and already shows a near-zero background in the region of interest, which is very promising. The scientists of the collaboration made an update in the occasion of the official inauguration on 11 and 12 December 2019.

Jul 15, 2020

In order for the images produced by the future MRI to be free of distortions or artifacts, the magnetic field generated by the Iseult magnet must be homogeneous to 0.5 PPM (parts per million) around the patient's brain. To meet this challenging specification, it was necessary to provision means of "shimming" the field, i.e. of correcting all the small defects that would inevitably arise from the manufacturing process. 5904 pieces of shim (small iron platelets) were screwed onto rails and installed inside the magnet tunnel. This first configuration was tested on Thursday, July 9, 2020 by mapping its effect on the magnetic field of Iseult at 3 T. The results are very encouraging as this first shimming iteration allowed to increase the homogeneity of the field in the useful zone from 138.8 to 3.2 PPM (value extrapolated to 11.72 T from magnetic measurements at 3 T).

Jun 04, 2020

On May 18th 2020, ESO formally closed the preliminary design review of the ELT/METIS thermal infrared instrument. Following this important milestone, the instrument enters into the final design phase (phase C) in which the its design will be frozen just before its building.

Feb 18, 2020

Following SPIRAL2's commissioning authorization issued by the French Nuclear Safety Authority (ASN) on July 8, 2019, many crucial steps were successfully completed by the end of 2019. A first proton beam was accelerated to 33 MeV, the nominal energy by the SPIRAL2 linear accelerator (LINAC) and a first test experiment was achieved the Neutron For Science (NFS) experimental room.


These first results in 2019 are very promising. They will continue in 2020 with the increase in beam power up to 10% of the maximum design power. In parallel test experiments in NFS will be carried out.

 

Jan 23, 2020

Arrived safely. The focal plane of the visible imager on the Euclid satellite has just been delivered by Irfu to the laboratory responsible for the instrument (MSSL/UK) to continue its integration into the satellite, which is scheduled to take off in 2022. 

The first studies of this focal plane have been carried out at Irfu since 2010 and after almost 10 years of development and testing, it was fully tested by Irfu in 2019. This Focal Plane is composed of 36 CDDs totalizing more than 600 million pixels. Each image acquired in flight by this focal plane will make it possible to characterize more than 50,000 galaxies. It is the second largest camera, observing in the visible, launched into space after that of the Gaïa satellite. In space, its observations will allow the measurement of galaxy deformations due to weak gravitational lensing effects induced by clusters of dark matter that light encounters on its way to us. These gravitational distortion effects measured at different ages of the Universe will provide measurements of the distribution of dark matter and will be a constraint on dark energy.

*Mullard Space Science Laboratory

 

Retour en haut