J. P. Chatelain

Thin scintillating tiles with high light yield for the OPAL endcaps

Arrays of thin scintillating tiles with embedded wavelength shifting fibre readout have been installed in the OPAL endcaps to improve trigger performance, time resolution and hermeticity for experiments at LEP II. The arrays were required to have high single-particle detection eƒciency, uniform response, low noise and good time resolution. Limited space for the detector, and a strong magnetic field in the endcap region, resulted in a need for high light output per unit thickness of scintillator, and remote readout. In addition, because of limited space for readout cables, a high light yield per embedded fibre was required. This paper describes the design and construction of a tile array that satisfies these requirements. A light yield of 14 photoelectrons per minimum ionizing particle and a time resolution of 3 ns were obtained during 1997 LEP operation. ( 1998 Elsevier Science B.V. All rights reserved. PACS: 01.52.#r; 29.; 29.40.Mc

Characterization of GEM detectors for application in the CMS muon detection system

The muon detection system of the Compact Muon Solenoid experiment at the CERN Large Hadron Collider is based on different technologies for muon tracking and triggering. In particular, the muon system in the endcap disks of the detector consists of Resistive Plate Chambers for triggering and Cathode Strip Chambers for tracking. At present, the endcap muon system is only partially instrumented with the very forward detector region remaining uncovered. In view of a possible future extension of the muon endcap system, we report on a feasibility study on the use of Micro-Pattern Gas Detectors, in particular Gas Electron Multipliers, for both muon triggering and tracking. Results on the construction and characterization of small triple-Gas Electron Multiplier prototype detectors are presented.

Beam test results for new full-scale GEM prototypes for a future upgrade of the CMS high-η Muon System

The CMS GEM collaboration is considering Gas Electron Multipliers (GEMs) for upgrading the CMS forward muon system in the 1.5 <; |η| <; 2.4 endcap region. GEM detectors can provide precision tracking and fast trigger information. They would improve the CMS muon trigger and muon momentum resolution and provide missing redundancy in the high-η region. Employing a new faster construction and assembly technique, we built four full-scale Triple-GEM muon detectors for the inner ring of the first muon endcap station. We plan to install these or further improved versions in CMS during the first long LHC shutdown in 2013/14 for continued testing. These detectors are designed for the stringent rate and resolution requirements in the increasingly hostile environments expected at CMS after the second long LHC shutdown in 2018/19. The new prototypes were studied in muon/pion beams at the CERN SPS. We discuss our experience with constructing the new full-scale production prototypes and present preliminary performance results from the beam test. We also tested smaller Triple-GEM prototypes with zigzag readout strips with 2 mm pitch in these beams and measured a spatial resolution of 73 μm. This readout offers a potential reduction of channel count and consequently electronics cost for this system while maintaining high spatial resolution.

Construction and performance of large-area triple-GEM prototypes for future upgrades of the CMS forward muon system

At present, part of the forward RPC muon system of the CMS detector at the CERN LHC remains uninstrumented in the high-η region. An international collaboration is investigating the possibility of covering the 1.6 &#60; |η| &#60; 2.4 region of the muon endcaps with large-area triple-GEM detectors. Given their good spatial resolution, high rate capability, and radiation hardness, these micro-pattern gas detectors are an appealing option for simultaneously enhancing muon tracking and triggering capabilities in a future upgrade of the CMS detector. A general overview of this feasibility study will be presented. The design and construction of small (10×10 cm2) and full-size trapezoidal (1 × 0.5 m2) triple-GEM prototypes will be described. During detector assembly, different techniques for stretching the GEM foils were tested. Results from measurements with x-rays and from test beam campaigns at the CERN SPS will be shown for the small and large prototypes. Preliminary simulation studies on the expected muon reconstruction and trigger performances of this proposed upgraded muon system will be reported.

Construction of the first full-size GEM-based prototype for the CMS high-η muon system

In view of a possible extension of the forward CMS muon detector system and future LHC luminosity upgrades, Micro-Pattern Gas Detectors (MPGDs) are an appealing technology. They can simultaneously provide precision tracking and fast trigger information, as well as sufficiently fine segmentation to cope with high particle rates in the high-eta region at LHC and its future upgrades. We report on the design and construction of a full-size prototype for the CMS endcap system, the largest Triple-GEM detector built to-date. We present details on the 3D modeling of the detector geometry, the implementation of the readout strips and electronics, and the detector assembly procedure.

An overview of the design, construction and performance of large area triple-GEM prototypes for future upgrades of the CMS forward muon system

GEM detectors are used in high energy physics experiments given their good spatial resolution, high rate capability and radiation hardness. An international collaboration is investigating the possibility of covering the 1.6 < |?| < 2.4 region of the CMS muon endcaps with large-area triple-GEM detectors. The CMS high-? area is actually not fully instrumented, only Cathode Strip Chamber (CSC) are installed. The vacant area presents an opportunity for a detector technology able to to cope with the harsh radiation environment; these micropattern gas detectors are an appealing option to simultaneously enhance muon tracking and triggering capabilities in a future upgrade of the CMS detector. A general overview of this feasibility study is presented. Design and construction of small (10cm ? 10cm) and full-size trapezoidal (1m ? 0.5m) triple-GEM prototypes is described. Results from measurements with x-rays and from test beam campaigns at the CERN SPS is shown for the small and large prototypes. Preliminary simulation studies on the expected muon reconstruction and trigger performances of this proposed upgraded muon system are reported.

Test beam results of the GE1/1 prototype for a future upgrade of the CMS high-η muon system

Gas Electron Multipliers (GEM) are an interesting technology under consideration for the future upgrade of the forward region of the CMS muon system, specifically in the 1.6 &#60; ∣η∣ &#60; 2:4 endcap region. With a sufficiently fine segmentation GEMs can provide precision tracking as well as fast trigger information. The main objective is to contribute to the improvement of the CMS muon trigger. The construction of large-area GEM detectors is challenging both from the technological and production aspects. In view of the CMS upgrade we have designed and built the largest full-size Triple-GEM muon detector, which is able to meet the stringent requirements given the hostile environment at the high-luminosity LHC. Measurements were performed during several test beam campaigns at the CERN SPS in 2010 and 2011. The main issues under study are efficiency, spatial resolution and timing performance with different inter-electrode gap configurations and gas mixtures. In this paper results of the performance of the prototypes at the beam tests will be discussed.

Gas flow simulations for gaseous detectors

One of the main issues regarding a gaseous detector is the gas flow inside the detector itself. A bad gas flow can affect irreversibly the chamber performance. On the other hand optimizing gas circulation inside the detector could allow a safe and reliable operation even with less gas consumption while at the same time maintaining high performance. Simulations and comparison between several different configurations are presented and discussed.