Fast algorithm for track segment and hit reconstruction in the CMS Cathode Strip Chambers

In this note, we propose an algorithm for fast and efficient track segment reconstruction in Cathode Strip Chambers used by CMS experiment for muon detection in the forward direction. The algorithm is designed to be CPU-efficient and is targeted for High Level Trigger (HLT, online reconstructed events pre-selection) purposes. The segment finding efficiency and the spatial resolution attainable with the proposed algorithm as well as the required CPU time are benchmarked using the MTCC data and found to surpass the HLT requirements

Overview of large area triple-GEM detectors for the CMS forward muon upgrade

In order to cope with the harsh environment expected from the high luminosity LHC, the CMS forward muon system requires an upgrade. The two main challenges expected in this environment are an increase in the trigger rate and increased background radiation leading to a potential degradation of the particle ID performance. Additionally, upgrades to other subdetectors of CMS allow for extended coverage for particle tracking, and adding muon system coverage to this region will further enhance the performance of CMS

A novel application of Fiber Bragg Grating (FBG) sensors in MPGD

We present a novel application of Fiber Bragg Grating (FBG) sensors in the construction and characterisation of Micro Pattern Gaseous Detector (MPGD), with particular attention to the realisation of the largest triple (Gas electron Multiplier) GEM chambers so far operated, the GE1/1 chambers of the CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of about 0.5 m2 active area each, employing three GEM foils per chamber, to be installed in the forward region of the CMS endcap during the long shutdown of LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM foils that are mechanically stretched in order to secure their flatness and the consequent uniform performance of the GE1/1 chamber across its whole active surface. So far FBGs have been used in high energy physics mainly as high precision positioning and re-positioning sensors and as low cost, easy to mount, low space consuming temperature sensors. FBGs are also commonly used for very precise strain measurements in material studies. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide GEM foils of the GE1/1 chambers. A network of FBG sensors have been used to determine the optimal mechanical tension applied and to characterise the mechanical tension that should be applied to the foils. We discuss the results of the test done on a full-sized GE1/1 final prototype, the studies done to fully characterise the GEM material, how this information was used to define a standard assembly procedure and possible future developments.Comment: 4 pages, 4 figures, presented by Luigi Benussi at MPGD 2015 (Trieste, Italy). arXiv admin note: text overlap with arXiv:1512.0848

Development and performance of Triple-GEM detectors for the upgrade of the muon system of the CMS experiment

The CMS Collaboration is evaluating GEM detectors for the upgrade of the muon system. This contribution will focus on the R&D performed on chambers design features and will discuss the performance of the upgraded detector

Design of a constant fraction discriminator for the VFAT3 front-end ASIC of the CMS GEM detector

In this work the design of a constant fraction discriminator (CFD) to be used in the VFAT3 chip for the read-out of the triple-GEM detectors of the CMS experiment, is described. A prototype chip containing 8 CFDs was implemented using 130 nm CMOS technology and test results are shown. © CERN 2016

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

Performance and Operation of the CMS Electromagnetic Calorimeter

The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

Charged particle detection performance of Gas Electron Multiplier (GEM) detectors for the upgrade of CMS endcap muon system at the CERN LHC

The Compact Muon Solenoid (CMS) detector is one of the two general-purpose detectors at the CERN LHC. LHC will provide exceptional high instantaneous and integrated luminosity after second long shutdown. The forward region |η| ≥ 1:5 of CMS detector will face extremely high particle rates in tens of kHz/cm2 and hence it will affect the momentum resolution, efficiency and longevity of the muon detectors. Here, η is pseudorapidity defined as η = -ln(tan(θ/2)), where θ is the polar angle measured from z-axis. To overcome these issues the CMSGEM collaboration has proposed to install new large size rate capable Triple Gas Electron Multiplier (GEM) detectors in the forward region of CMS muon system. The first set of Triple GEM detectors will be installed in the GE1/1 region (1:6 <; |η| <; 2.2) of the muon endcap during the long shutdown 2 (LS2) of the LHC. Towards this goal, full size CMS Triple GEM detectors have been fabricated and tested at the CERN SPS, H2 and H4 test beam facility. The GEM detectors were operated with two gas mixtures: Ar/CO2 (70/30) and Ar/CO2/CF4 (45/15/40). In 2014, good quality data was collected during test beam campaigns. In this paper, the performance of the detectors is summarized based on their tracking efficiency and time resolution

The Bieti Church: the Problem of Dating and the Origin of Masters

Submitted on 13 June, 2018. Accepted on 30 September, 2018.Поступила в редакцию 13.06.2018. Принята к печати 30.09.2018.Статья посвящена памятнику архитектуры, находящемуся в среднем течении реки Меджуды в районе Ксанского ущелья в исторической грузинской области Шида-Картли. Храм в Биети является уникальной постройкой для данной местности, представляя собой полупещерный зальный храм. Южная часть здания выложена из ширими и булыжника, а северная высечена в примыкающей скале. Основными источниками для изучения памятника является храмовая архитектура Грузии, прежде всего, области Шида-Картли, а также Армении, Каппадокии и Л икаонии. К изучению был привлечен эпиграфический материал — строительные и поминальные надписи на храмах в верховьях Лиахви и Ксани, а также основной летописный памятник Грузии — Картлис Цховреба. В тексте рассматриваются особенности архитектуры храма в Биети: строительной техники, декорации и др. Среди храмов исторической области Шида-Картли храм в Биети стоит особняком: большинство ближайших аналогий ему находится в Малой Азии. Основываясь на анализе Биетской строительной надписи и исторических данных, связанных с этой частью Шида-Картли, автор статьи предлагает уточненную датировку памятника, а благодаря стилистическому и типологическому анализу архитектуры, изучению техники строительства выдвигает предположение о работе в Биети мастеров из Малой Азии. Несмотря на то, что новации Биетского храма, привнесенные извне, появляются в местной архитектуре лишь однажды в церкви села Кусирети близ Цхинвали, храм в Биети (благодаря использованию традиционных архитектурных приемов) оказывается связующим звеном между ранними храмами верховьев реки Ксани третьей четверти IX в. и последующими постройками того же направления в верховьях реки Лиахви.This article considers a monument of architecture located in the middle reaches of the Mejuda River in the Ksani gorge in the historical Georgian region Shida Kartli. The Bieti church is a unique monument of the region, representing a half-cave building. The southern part of the church is built of travertine and cobblestone, and the northern part is carved into the adjacent rock. The main primary source for the study of the monument is the ecclesiastical architecture of Georgia, mostly Shida Kartli region, as well as Armenia, Cappadocia, and Lycaonia. The study refers to epigraphic material, i.e. building and memorial inscriptions on the churches in the upper courses of the Liakhvi and Ksani Rivers, as well as the main chronicle of Georgia, Kartlis Tskhovreba. The author analyses the architecture of the Bieti church, its construction technics, decoration, etc. Among the monuments of the historical region of Shida Kartli, the church in Bieti stands alone: most of its closest analogues can be found in Asia Minor. Based on the analysis of the Bieti building inscription and historical data related to this part of Shida Kartli, the author proposes a more accurate dating of the monument. Additionally, based on the stylistic and typological analysis of architecture and the study of building technics, the author suggests that masters from Asia Minor may have been involved in building the church in Bieti. Despite the fact that the innovations of Bieti monastery brought from outside occur in local architecture only once in the church of the village of Kusireti near Tskhinval, the church in Bieti (due to the use of traditional architectural technics) is a link between the early architecture of the upper course of the Ksani River of the third quarter of the ninth century and subsequent buildings of the same direction in the upper course of the Liakhvi River