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International audience; Due to their simplicity and accuracy for reconstructing particle trajectories, Micromegas (Micro-MEsh-GAseous Structure) and Gas Electron Multiplier (GEM) detectors are commonly used as readout systems in Time Projection Chambers (TPCs). The main limitation of these two types of detectors is the ion backflow (IBF), which may result in space charge in a TPC. We present in this article a new Micro-Pattern Gaseous Detector (MPGD) structure, which combines a micro-mesh and a set made of a GEM surmounted by a micro-mesh at only a few hundreds μm above. We report the performance results of two prototypes using this new structure, and compare them to a single Micromegas and a hybrid detector composed of a Micromegas and a GEM with a few millimeters gap. Finally, we show that this new detector is capable of reducing the ion backflow to less than 0.2% for a total gain of around 2000.

International audience; Due to their construction simplicity and accuracy for reconstructing particle trajectories, Micromegas (mesh-GAseous Structure) and Gas Electron Multiplier (GEM) detectors are commonly used as readout systems in Time Projection Chambers (TPCs). The main limitation of these two types of detectors is the ion backflow, which may result in space charge in the TPC. We present a new Micro-Pattern Gaseous Detector (MPGD) structure, which combines a mesh and a set made of a GEM surmounted by a mesh at only a few hundreds μm above. We report the performance results of two prototypes using this new structure. We show that this new detector is capable of reducing the ion backflow to less than 0.2% for a total gain of around 2000.

International audience; The performance of the first large resistive Micromegas detectors with 2D readout and genetic multi-plexing is presented. These detectors have a × 50 50cm 2 active area and are equipped with 1024 strips both in X-and Y-directions. The same genetic multiplexing pattern is applied on both coordinates, resulting in the compression of signals on × 2 61 readout channels. Four such detectors have been built at CERN, and extensively tested with cosmics. The resistive strip film allows for very high gain operation, compensating for the charge spread on the 2 dimensions as well as the S N / loss due to the huge, 1 nF input capacitance. This film also creates a significantly different signal shape in the X-and Y-coordinates due to the charge evacuation along the resistive strips. All in all a detection efficiency above 95% is achieved with a 1 cm drift gap. Though not yet optimal, the measured 300 mm spatial resolution allows for very precise imaging in the field of muon tomography, and some applications of these detectors are presented.

The KLOE-2 experiment started its data taking campaign in November 2014 with an upgraded tracking system including an Inner Tracker built with the cylindrical GEM technology, to operate together with the Drift Chamber improving the apparatus tracking performance. The Inner Tracker is composed of four cylindrical triple-GEM, each provided with an X–V strips-pads stereo readout and equipped with the GASTONE ASIC developed inside the KLOE-2 collaboration. Although GEM detectors are already used in high energy physics experiment, this device is considered a frontier detector due to its cylindrical geometry: KLOE-2 is the first experiment to use this novel solution. The results of the detector commissioning, detection efficiency evaluation, calibration studies and alignment, both with dedicated cosmic-ray muon and Bhabha scattering events, will be reported.

IDEA (Innovative Detector for Electron–positron Accelerators) is a detector concept designed for a future leptonic collider operating as a Higgs factory. It is based on innovative detector technologies developed over years of R&D. In September 2018, prototypes of the proposed sub-detectors have been tested for the first time on a beam line at CERN. The preliminary results from this test of a full slice of the IDEA detector and standalone measurements of dual read-out calorimeter prototypes are presented.

We developed a novel design of a Micro Pixel Chamber ( μ -PIC) with resistive electrodes for a charged particle tracking detector in high rate applications. Diamond Like Carbon (DLC) thin film is used for the cathodes. The resistivity can be controlled flexibly ( 1 0 5 − 7 Ω /sq.) with high uniformity. The fabrication process was greatly improved and the resistive μ -PIC could be operated with an area of 10 × 10 cm 2 . Resistors for the HV bias and capacitors for the AC coupling were completely removed by applying PCB and carbon sputtering techniques, and the resistive μ -PIC became a very compact detector. The performance of our new resistive μ -PIC was measured in various ways. Consequently, it was possible to attain high gas gains ( > 1 0 4 ), high detection efficiency, and position resolution better than 100 μ m. The spark probability was reduced, and the new resistive μ -PIC was operated stably under fast neutrons irradiation. These features offer solutions for a charged particle tracking detector in future high rate applications.

NEWAGE is a direction-sensitive WIMP search experiment using micro pixel chamber. After our first underground measurement at Kamioka in 2009, we constructed a new detector, which was designed to have a twice larger target volume with low background material, a lowered threshold of 50 keV, an improved data acquisition system. In 2013, dark matter search in Kamioka underground laboratory was performed. We have succeeded to lower the background level by about one order of magnitude., 13th International Conference on Topics in Astroparticle and Underground

A multi-institutional collaboration is investigating the possibility of enhancing muon tracking and triggering capabilities in the small-angle region $1.6 < \rm{abs}(\eta) < 2.1$ of the CMS experiment at the LHC by instrumenting the end-cap muon system with large-area gas electron multiplier (GEM) detectors. A first trapezoidal prototype triple-GEM detector of size 1 m by 0.5 m was built and operated successfully in a test beam at CERN in October 2010. Front-end readout boards utilizing the ``VFAT" chip are mounted in a regular array directly on the chambers. High voltage is provided by a compact divider board implemented with surface mount components. A tracker equipped with small GEM detectors was used to precisely measure the hit position in the large-area detector. A spatial resolution of 0.29 mm was measured in a region with average strip pitch of 1.1 mm, and $\sim$98\% hit efficiency was achieved at full operating voltage. An additional prototype chamber is constructed and will undergo beam tests this summer with operation in a 3T magnetic field.

The Micro Pixel Chamber (μ-PIC) is being developed a sacandidate for the muon system of the ATLAS detector for upgrading in LHC experiments. The μ-PIC is a micro-pattern gaseous detector that doesn’t have floating structure such as wires, mesh, or foil. This detector can be made by printed-circuit-board (PCB) technology, which is commercially available and suited for mass production. Operation tests have been performed under high flux neutrons under similar conditions to the ATLAS cavern. Spark rates are measured using several gas mixtures under 7 MeV neutron irradiation, and good properties were observed using neon, ethane, and CF4 mixture of gases.Using resistive materials as electrodes, we are also developing a new μ-PIC, which is not expected to damage the electrodes in the case of discharge sparks.