ANTARES: the first undersea neutrino telescope

The ANTARES Neutrino Telescope was completed in May 2008 and is the first operational Neutrino Telescope in the Mediterranean Sea. The main purpose of the detector is to perform neutrino astronomy and the apparatus also offers facilities for marine and Earth sciences. This paper describes the design, the construction and the installation of the telescope in the deep sea, offshore from Toulon in France. An illustration of the detector performance is given

Discharge rate measurements for Micromegas detectors in the presence of a longitudinal magnetic field

International audienceWe present first discharge rate measurements for Micromegas detectors in the presence of a high longitudinal magnetic field in the GeV kinematical region. Measurements were performed by using two Micromegas detectors and a photon beam impinging a CH2 target in the Hall B of the Jefferson Laboratory. One detector was equipped with an additional GEM foil, and a reduction of the discharge probability by two orders of magnitude compared to the stand-alone Micromegas was observed. The detectors were placed in the FROST solenoid providing a longitudinal magnetic field up to 5 T. It allowed for precise measurements of the discharge probability dependence with a diffusion-reducing magnetic field. Between 0 and 5 T, the discharge probability increased by a factor of 10 for polar angles between 19o and 34o. A GEANT4-based simulation developed for sparking rate calculation was calibrated against these data in order to predict the sparking rate in a high longitudinal magnetic field environment. This simulation is then used to investigate the possible use of Micromegas in the Forward Vertex Tracker (FVT) of the future CLAS12 spectrometer. In the case of the FVT a sparking rate of 1 Hz per detector was obtained at the anticipated CLAS12 luminosity

Design and development of Ionization Profile Monitor for the Cryogenic sections of the ESS Linac

International audienceSaclay CEA/IRFU is working for the delivery of five Non-Invasive Profile Monitors in the frame of the in-kind contribution agreement signed with the European Spallation Source. Neutrons will be produced by spallation reactions of 2 GeV proton beam impinging on a Tungsten target. To accelerate protons a powerful linear accelerator of 5MW is under construction. Diagnostic devices are mandatory tools for the tuning and protection of the machine. The non-invasive profile monitors provide a measurement of the beam profile in transverse directions to the beam propagation. This project raises several physical and technical challenges including low signal detection of ions or electrons, profile distortions induced by the beam Space Charge effect and non-uniformities of electric field. Simulation and model of the critical aspects of the detector have been performed in order to prove the performance and the feasibility of the detector. A series of prototypes has been built with different readout types, and tested in real conditions at the 3MeV proton accelerator IPHI. All of them show some advantages and drawbacks revealed by the tests in real beam conditions. In this paper we present the results of the tests for the various configuration readout systems to agree with the model and simulation of the detector. In concluding remarks, we will discuss the performance of the prototypes and point out the camerabased one to be the more suitable for the final design.Key words: Beam diagnostic / Linear proton accelerators / MCP / Strip detector / Particle beam measurement

Design and development of Ionization Profile Monitor for the Cryogenic sections of the ESS Linac

Saclay CEA/IRFU is working for the delivery of five Non-Invasive Profile Monitors in the frame of the in-kind contribution agreement signed with the European Spallation Source. Neutrons will be produced by spallation reactions of 2 GeV proton beam impinging on a Tungsten target. To accelerate protons a powerful linear accelerator of 5MW is under construction. Diagnostic devices are mandatory tools for the tuning and protection of the machine. The non-invasive profile monitors provide a measurement of the beam profile in transverse directions to the beam propagation. This project raises several physical and technical challenges including low signal detection of ions or electrons, profile distortions induced by the beam Space Charge effect and non-uniformities of electric field. Simulation and model of the critical aspects of the detector have been performed in order to prove the performance and the feasibility of the detector. A series of prototypes has been built with different readout types, and tested in real conditions at the 3MeV proton accelerator IPHI. All of them show some advantages and drawbacks revealed by the tests in real beam conditions. In this paper we present the results of the tests for the various configuration readout systems to agree with the model and simulation of the detector. In concluding remarks, we will discuss the performance of the prototypes and point out the camerabased one to be the more suitable for the final design

Discharge studies in Micromegas detectors in low energy hadron beams

International audienceWe present measurements of discharge rates in various Micromegas detectors in low energy hadron beams for applications foreseen at the future experiments CLAS12 at JLab and MINOS at GSI. The tests were performed in the T11 beam line of the CERN/PS using hadron beams with momentum between 0.2 and 3 GeV/c. The discharge probability decreases smoothly below 1 GeV/c, except at some specific energies where narrow peaks are observed. The position of the peaks corresponds to the stop point of protons and heavier particles, predicted by the Geant4 simulation. Discharge rates were also measured using Micromegas prototypes equipped with a GEM foil as foreseen for the COMPASS experiment at CERN

Discharge studies in micromegas detectors in a 150GeV/c pion beam

International audienceA detailed study of several Micromegas detectors prototyped for the COMPASS and CLAS12 experiments is presented. Using a 150 GeV/c pion beam, the discharge probability was measured for several detector variants including bulk and non-bulk Micromegas. A detector equipped with an additional GEM foil as pre-amplification stage was also tested. A resistive coating of the readout strips was found to reduce the amplitude of the discharge by at least two orders of magnitude which was below the detection limit of the experimental setup. The effects of the micro-mesh type and material were investigated as well as the influence of the drift gap. Response in the presence of a 1.5 T transverse magnetic field was also studied. The measurements presented were performed during a RD51 beam test period

Micromegas for beam loss monitoring

International audienceThe early detection of beam losses and the alarm to the machine protection system in accelerators are crucial for the safe operation of the machine. In the low energy region of the hadron accelerators, only neutrons and photons are produced in the case of a beam loss. However, photons are also emitted by electrons at the RF cavities, becoming a natural background for losses identification. A new kind of beam loss monitors have been conceived to extend the sensitivity to the low energy region of the high intensity hadron accelerators. They are based on Micromegas detectors sensitive to fast neutrons. The appropriate configuration of the Micromegas operating conditions will allow a fast response, a sensitivity to small beam losses and a suppressed sensitivity to photons. In this paper the operation principle and the system developed for the European Spallation Source will be presented, with focus on the results obtained at different irradiation facilities. First time proof of operation in real conditions, with the detection of beam losses, will be also shown with measurements performed at LINAC4 (CERN)