Calorimetry at future linear colliders could be based on a particle flow approach where granularity is the key to high jet energy resolution. Among different technologies, Micromegas chambers with 1 cm2 pad segmentation are studied for the active medium of a hadronic calorimeter. A chamber of 1 m2 with 9216 channels read out by a low noise front-end ASIC called MICROROC has recently been constructed and tested. Chamber design, ASIC circuitry and preliminary test beam results are reported.
The CALICE Semi-Digital Hadronic Calorimeter (SDHCAL) prototype, built in 2011, was exposed to beams of hadrons, electrons and muons in two short periods in 2012 on two different beam lines of the CERN SPS. The prototype with its 48 active layers, made of Glass Resistive Plate Chambers and their embedded readout electronics, was run in triggerless and power-pulsing mode. The performance of the SDHCAL during the test beam was found to be very satisfactory with an efficiency exceeding 90% for almost all of the 48 active layers. A linear response (within 5%) and a good energy resolution are obtained for a large range of hadronic energies (5-80GeV) by applying appropriate calibration coefficients to the collected data for both the Digital (Binary) and the Semi-Digital (Multi-threshold) modes of the SDHCAL prototype. The Semi-Digital mode shows better performance at energies exceeding 30GeV
With the ultimate goal of developing a pixel-based readout for a TPC at the ILC, a GridPix readout system consisting of one Timepix3 chip with an integrated amplification grid was embedded in a prototype detector. The performance was studied in a testbeam with 2.5 GeV electrons at the ELSA accelerator in Bonn. The error on the track position measurement both in the drift direction and in the readout plane is dominated by diffusion. Systematic uncertainties are limited to below 10 $mu$m. The GridPix can detect single ionization electrons with high efficiency, which allows for energy loss measurements and particle identification. From a truncated sum, an energy loss (dE/dx) resolution of 4.1% is found for an effective track length of 1 m. Using the same type of chips, a Quad module was developed that can be tiled to cover a TPC readout plane at the ILC. Simulation studies show that a pixel readout can improve the momentum resolution of a TPC at the ILC by about 20%.
A combination Time Projection Chamber-Cherenkov prototype detector has been developed as part of the Detector R&D Program for a future Electron Ion Collider. The prototype was tested at the Fermilab test beam facility to provide a proof of principle to demonstrate that the detector is able to measure particle tracks and provide particle identification information within a common detector volume. The TPC portion consists of a 10x10x10cm3 field cage, which delivers charge from tracks to a 10x10cm2 quadruple GEM readout. Tracks are reconstructed by interpolating the hit position of clusters on an array of 2x10mm2 zigzag pads The Cherenkov component consists of a 10x10cm2 readout plane segmented into 3x3 square pads, also coupled to a quadruple GEM. As tracks pass though the drift volume of the TPC, the generated Cherenkov light is able to escape through sparsely arranged wires making up one side of the field cage, facing the CsI photocathode of the Cherenkov detector. The Cherenkov detector is thus operated in a windowless, proximity focused configuration for high efficiency. Pure CF4 is used as the working gas for both detector components, mainly due to its transparency into the deep UV, as well as its high N0. Results from the beam test, as well as results on its particle id capabilities will be discussed.
New Micromegas (Micro-mesh gaseous detectors) are being developed in view of the future physics projects planned by the COMPASS collaboration at CERN. Several major upgrades compared to present detectors are being studied: detectors standing five times higher luminosity with hadron beams, detection of beam particles (flux up to a few hundred of kHz/mm^{2}, 10 times larger than for the present Micromegas detectors) with pixelized read-out in the central part, light and integrated electronics, and improved robustness. Two solutions of reduction of discharge impact have been studied, with Micromegas detectors using resistive layers and using an additional GEM foil. Performance of such detectors has also been measured. A large size prototypes with nominal active area and pixelized read-out has been produced and installed at COMPASS in 2010. In 2011 prototypes featuring an additional GEM foil, as well as an resistive prototype, are installed at COMPASS and preliminary results from those detectors presented very good performance. We present here the project and report on its status, in particular the performance of large size prototypes with an additional GEM foil.
For the International Large Detector (ILD) at the planned International Linear Collider (ILC) a Time Projection Chamber (TPC) is foreseen as the main tracking detector. To achieve the required point resolution, Micro-Pattern Gaseous Detectors (MPGD) will be used in the amplification stage. A readout module using a stack of three Gas Electron Multipliers (GEM) for gas amplification was developed at DESY and tested at the DESY II Test Beam Facility. After introducing the readout module and the infrastructure at the test beam facility, the performance related to single point and double-hit resolution of three of these modules is presented. This is followed by results on the particle identification capabilities of the system, using the specific energy loss dE/dx, and simulation studies, aimed to investigate and quantify the impact of high granularity on dE/dx resolution. In addition, a new and improved TPC field cage and the LYCORIS Large-Area Silicon-Strip Telescope for the test beam are described. The LYCORIS beam telescope is foreseen to provide a precise reference of the particle trajectory to validate the momentum resolution measured with a large TPC prototype. For this purpose, it is being installed and tested at the test beam facility within the so-called PCMAG (Persistent Current Magnet).