[en] The work presented is this thesis is an investigation of the spatial resolution of a Microstrip Gas Chamber (MSGC) as an imaging device for X-rays. Applications include digital radiology and experiments with synchrotron radiation. The investigation was done for X-ray energies around 20 keV, and the detector was evaluated for digital mammography

[en] Two RICH detectors provide positive charged hadron identification in the LHCb experiment at the Large Hadron Collider at CERN. RICH 1 covers the full acceptance of the spectrometer and contains two radiators: aerogel and C₄F₁₀. RICH 2 covers half the acceptance and uses CF₄ as a Cherenkov radiator. Photon detection is performed by the Hybrid Photon Detectors (HPDs), with silicon pixel sensors and bump-bonded readout encapsulated in a vacuum tube for efficient, low-noise single photon detection. The LHCb RICH detectors form a complex system of three radiators, 120 mirrors and 484 photon detectors operating in the very challenging environment of the LHC. The high performance of the system in pion and kaon identification in the momentum range of 2–100 GeV/c is reached only after careful calibration of many parameters. Operational efficiency above 99% was achieved by a high level of automatization in the operation of the detectors, from switching-on to error recovery. The challenges of calibrating and operating such a system will be presented. - Highlights: • This paper describes the operation and calibration of the LHCb RICH detectors. • The scintillation of CF₄ was successfully suppressed with CO₂. • The refractive index of the gas radiators was calibrated with data to an accuracy better than 0.1%. • The Hybrid Photons Detectors were calibrated for operation in a magnetic field without loss of resolution

[en] Hadron identification in the LHCb experiment is performed by two Ring Imaging Cherenkov (RICH) detectors, comprising three radiators and 484 Hybrid Photon Detectors (HPDs). A well calibrated and aligned RICH system is essential for providing the particle identification performance necessary for realising the physics goals. The total number of mirrors in the two RICH detectors is 116 and they must be aligned to an accuracy of 0.1 mrad in order not to degrade the performance of the system. The refractive indices n of the two gas radiators, namely C₄F₁₀ and CF₄, are expected to change with atmospheric pressure, and the refractivity (n-1) will be monitored to an accuracy of 0.1% from physics data. The Cherenkov angle resolutions and photon yields will be calibrated using saturated Cherenkov rings and particles of known type. Both RICH detectors operate in the fringe field of the LHCb dipole magnet, which produces image distortions of the HPDs. Solutions to correct for these distortions are in the implementation phase. Finally, the overall performance of the RICH system for hadron identification will be evaluated using samples of pions and kaons identified from D^* decays, which can be isolated with high purity independently of the RICH itself

[en] The LHCb RICH system provides hadron identification over a wide momentum range (2–100 GeV/c). This detector system is key to LHCb's precision flavour physics programme, which has unique sensitivity to physics beyond the standard model. This paper reports on the performance of the LHCb RICH in Run II, following significant changes in the detector and operating conditions. The changes include the refurbishment of significant number of photon detectors, assembled using new vacuum technologies, and the removal of the aerogel radiator. The start of Run II of the LHC saw the beam energy increase to 6.5 TeV per beam and a new trigger strategy for LHCb with full online detector calibration. The RICH information has also been made available for all trigger streams in the High Level Trigger for the first time.

[en] Pulse heights and hit multiplicities from X-rays in MSGCs have been simulated using the integrated tiger series codes. Simulations were made for a 200 μm pitch MSGC filled with Xe/CO₂ at 2-7 bar and for a 300 μm MSGC filled with Ar/isobutane at 1 bar. The results agree well with experiments. (orig.)

[en] The RICH detectors of the LHCb experiment have provided particle identification with excellent performance during Runs 1 and 2 of the LHC . Currently the LHCb experiment is undergoing an upgrade to allow, starting from 2021, data collection at 5 times the instantaneous luminosity of the period 2010-2019 (up to $2\times <!--\; ??\; -->{10}^{33}$cm${}^{-<!--\; ???\; -->2}$s${}^{-<!--\; ???\; -->2}$ ) with the aim to collect a data sample corresponding to 50 fb${}^{-<!--\; ???\; -->1}$. The required upgrades to detectors and electronics are significant, with the RICH system changing all of the photon detectors and a full replacement of the upstream RICH detector. The existing Hybrid Photon Detectors (HPD) are being replaced by two types of Multi-Anode Photomultiplier Tubes (MaPMT) with electronics capable of recording data at the full LHC collision frequency of 40 MHz using a time gate of 6 ns. The required 3072 MaPMTs have undergone detailed characterisation, measuring gain and uniformity across channels and the photo-cathode quantum efficiency on a smaller sample. The status of the project will be presented.

[en] 2D silicon strip sensors using particle physics readout technology have been evaluated as mammographic detectors. Two different versions of the APV series of front-end electronics were used that provided different noise levels. The sensors were evaluated using a typical mammography X-ray spectrum. The spatial resolution was evaluated using line pair test patterns and the modulation transfer function (MTF) was measured using the Edge Response Function. Low contrast performance was measured using the TOR(MAX) test object. Limiting spatial resolution of 52 μm was obtained and an MTF value of 0.1 at 16 lp/mm. The low contrast performance was estimated from 250, 500 μm and 6 mm diameter objects and was found to be 11.5%, 7% and better than 3.8%, respectively

[en] A two stage position-sensitive gas proportional counter has been constructed by tightly coupling a Gas Electron Multiplier (GEM) with a Micro-Groove Detector (MGD). The GEM was used as the first amplifying stage and was optimised to transmit close to 100% of the primary charge even at very high drift fields (10 kV/cm). Very narrow GEM-MGD separations (0-600 μm) were used so that the active volume of the detector is still very thin (3-3.6 mm) and the required drift field could be maintained using an acceptable drift voltage (around 4000 V). Very high combined gains (up to 3x10⁵) were obtained with this system. The detector was found to be spark-free in the presence of HIPs (alpha particles) up to gains in excess of 20 000

[en] The installation of virtual visit services by the LHC collaborations began shortly after the first high-energy collisions were provided by the CERN accelerator in 2010. The experiments: ATLAS [1], CMS [2], LHCb [3], and ALICE [4] have all joined in this popular and effective method to bring the excitement of scientific exploration and discovery into classrooms and other public venues around the world. Their programmes, which use a combination of video conference, webcast, and video recording to communicate with remote audiences have already reached tens of thousands of viewers, and the demand only continues to grow. Other venues, such as the CERN Control Centre, are also considering similar permanent installations.

We present a summary of the development of the various systems in use around CERN today, including the technology deployed and a variety of use cases. We then lay down the arguments for the creation of a CERN-wide service that would support these programmes in a more coherent and effective manner. Potential services include a central booking system and operational management similar to what is currently provided for the common CERN video conference facilities. Certain choices in technology could be made to support programmes based on popular tools including (but not limited to) Skype™ [5], Google Hangouts [6], Facebook Live [7], and Periscope [8]. Successful implementation of the project, which relies on close partnership between the experiments, CERN IT CDA [9], and CERN IR ECO [10], has the potential to reach an even larger, global audience, more effectively than ever before. (paper)

[en] We introduce the WELL detector, a new type of position-sensitive gas proportional counter produced using advanced Printed Circuit Board (PCB) technology. The WELL is based on a thin kapton foil, copper-clad on both sides. Charge amplifying micro-wells are etched into the first metal and kapton layers. These end on a micro-strip pattern which is defined on the second metal plane. The array of micro-strips is used for read-out to obtain 1-D positional information. First results from our systematic assessment of this device are reported