After almost a year collecting data from proton-proton collisions, the LHC at CERN began the injection of lead ions at the beginning of November, with the first collisions obtained on November 8. The energy in the nucleon-nucleon center of mass is 2.76 TeV, around ten times greater than that achieved previously by the RHIC in Brookhaven USA. The first results from ALICE have been made available without delay.
A team of physicists, engineers and technicians from IRFU are developing a new generation of MicroMegas trackers. The planned Compass II experiment at CERN, together with the Clas12 experiment at the Jefferson Lab, will impose new operational constraints preventing the current generation of trackers from working with nominal performance. Tests on a new generation of detectors have been carried out using particle beams generated at CERN. These tests have achieved both of their objectives; a reduction of the discharge rate which is a limiting factor in high flux experiments such as Compass, and a demonstration of their ability to operate under intense magnetic fields, a requirement for the gas detectors of the future Clas12 spectrometer. In a wider perspective, the development of MicroMegas technology is an essential component of the current IRFU research strategy with the recent establishment of a workshop dedicated to the design of this type of detectors.
The CHyMENE project (Cible d'Hydrogène Mince pour l'Etude des Noyaux Exotiques -Thin hydrogen target for the study of exotic nuclei) has the ambitious goal of producing a thin target of pure hydrogen, without using a container, suitable for experiments using the low-energy heavy ion beam planned for SPIRAL2.
A team from IRFU (SPhN and SACM) and from l'Inac/SBT have recently applied cryogenic techniques to successfully produce a ribbon of solid hydrogen 100 μm thick. The target will soon be tested in the beam. This will be a world first.
Below: Interview with Alain GILLIBERT, who is working on the CHyMENE project with Alexandre OBERTELLI and Emmanuel POLLACO
Start image: a solid hydrogen ribbon of extruded H2 (width 10 mm, thickness 100 μm), viewed through the porthole of the vacuum chamber (Photo V. Lapoux).
The Double Chooz collaboration recently completed its neutrino detector which will see anti-neutrinos coming from the Chooz nuclear power plant in the French Ardennes. The experiment is now ready to take data in order to measure fundamental neutrino properties with important consequences for particle and astro-particle physics.
contacts:
A company from the Vosges Department in France, NEOTEC, received the 2009 "Outstanding Implementations" award, at the International MIDEST Exhibition attended by the Industry Minister, Christian Estrosi, for their production of very special chambers. This equipment forms part of an important component of the Double-Chooz experiment which, before the end of the year, will measure neutrinos emitted by the reactor at the Chooz nuclear power station in the Ardennes.
At a meeting in Brussels of the NUPECC Committee(1) on December 9, the researchers presented their long term plan for maintaining the leading position currently enjoyed by European institutions in the field of nuclear physics. The Spiral2 project in Caen, a collaboration between the CNRS/IN2P3(2) and the CEA/DSM(3), is one of the projects already contributing to this European strategy.
The long term plan for nuclear physics may be found on the NUPECC site in a number of forms, including the full 200 page report, a 20 page summary and a 20 minute video.
http://www.nupecc.org/index.php?display=lrp2010/main
Contact:
Philippe CHOMAZ, chef de l'Institut
The instrument known as MUSETT1 detected its first heavy nuclei during a commissioning experiment that took place in early April 2010 at the GANIL2 accelerator in Caen. MUSETT was built for identifying very heavy elements: transfermium, which are the elements beyond fermium (Z=100). Nuclear physicists are interested in these extreme state of matter for testing the theoretical models that describe the nuclei. Initial results obtained with MUSETT are highly satisfactory, providing very good identification of the produced isotopes, thanks to an original method called ‘genetic correlations’. This method can tag nuclei by detecting its decay. MUSETT provides a preview of the detection for the future Super Separator Spectrometer S3, dedicated to the hyper-intense SPIRAL23 beams, which will allow scientists to explore the heaviest nuclei.
The CHyMENE project (Cible d'Hydrogène Mince pour l'Etude des Noyaux Exotiques -Thin hydrogen target for the study of exotic nuclei) has the ambitious goal of producing a thin target of pure hydrogen, without using a container, suitable for experiments using the low-energy heavy ion beam planned for SPIRAL2.
A team from IRFU (SPhN and SACM) and from l'Inac/SBT have recently applied cryogenic techniques to successfully produce a ribbon of solid hydrogen 100 μm thick. The target will soon be tested in the beam. This will be a world first.
Below: Interview with Alain GILLIBERT, who is working on the CHyMENE project with Alexandre OBERTELLI and Emmanuel POLLACO
Start image: a solid hydrogen ribbon of extruded H2 (width 10 mm, thickness 100 μm), viewed through the porthole of the vacuum chamber (Photo V. Lapoux).
A team of physicists, engineers and technicians from IRFU are developing a new generation of MicroMegas trackers. The planned Compass II experiment at CERN, together with the Clas12 experiment at the Jefferson Lab, will impose new operational constraints preventing the current generation of trackers from working with nominal performance. Tests on a new generation of detectors have been carried out using particle beams generated at CERN. These tests have achieved both of their objectives; a reduction of the discharge rate which is a limiting factor in high flux experiments such as Compass, and a demonstration of their ability to operate under intense magnetic fields, a requirement for the gas detectors of the future Clas12 spectrometer. In a wider perspective, the development of MicroMegas technology is an essential component of the current IRFU research strategy with the recent establishment of a workshop dedicated to the design of this type of detectors.
The pion, predicted by Yukawa in 1935 and discovered in 1947, was the first of a family of particles called mesons: a family that has continued to grow ever since. Ordinary mesons consist of a quark and an antiquark. The theory of strong interaction also predicts the existence of more complex mesons, called ‘exotic' mesons. The existence of exotic mesons has not yet been formally proven, but scientists have been searching for them for over more than a decade. The Compass experiment at CERN, an international partnership collaboration that includes a team from the Nuclear Physics department of IRFU, revealed an exotic meson during a preliminary experiment. This is a promising sign that many more particles will may be found in the future. The meson observed by the COMPASS physicists has a mass of 1660 MeV/c2 (Millions of electron-volts/c2). Its mass is about 12 times greater than that of a pion, but that in itself is not surprising. It was the quantum properties of this particle that intrigued the scientists. These properties are ruled out for ordinary mesons, and indicate that this must have been an exotic meson.
These results have just been published in Physical Review Letters (PRL 104, 241803, 2010).
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Dernière mise à jour : Nov 13th, 2024
