Noémi Béni

This work investigates the performance and the radiation hardness capability of optical thermo-hygrometers based on Fibre Bragg Gratings (FBG) for humidity monitoring in the Compact Muon Solenoid (CMS), one of the four experiments running at CERN in Geneva. A thorough campaign of characterization was performed on 80 specially produced Polyimide-coated RH FBG sensors and 80 commercial temperature FBG sensors. Sensitivity, repeatability and accuracy were studied on the whole batch, putting in evidence the limits of the sensors, but also showing that they can be used in very dry conditions. In order to extract the humidity measurements from the sensor readings, commercial temperature FBG sensors were characterized in the range of interest. Irradiation campaigns with ionizing radiation (γ-rays from a Co60 source) at incremental absorbed doses (up to 210 kGy for the T sensors and up to 90 kGy for the RH sensors) were performed on sample of T and RH-Sensors. The results show that the sensitivity of the sensors is unchanged up to the level attained of the absorbed dose, while the natural wavelength peak of each sensor exhibits a radiation-induced shift (signal offset). The saturation properties of this shift are discussed.

Production of neutrinos is abundant at LHC. Flavour composition and energy reach of the neutrino flux from proton-proton collisions depend on the pseudorapidity $\eta$. At large $\eta$, energies can exceed the TeV, with a sizeable contribution of the $\tau$ flavour. A dedicated detector could intercept this intense neutrino flux in the forward direction, and measure the interaction cross section on nucleons in the unexplored energy range from a few hundred GeV to a few TeV. The high energies of neutrinos result in a larger $\nu$N interaction cross section, and the detector size can be relatively small. Machine backgrounds vary rapidly while moving along and away from the beam line. Four locations were considered as hosts for a neutrino detector: the CMS quadruplet region (~25 m from CMS Interaction Point (IP)), UJ53 and UJ57 (90 and 120 m from CMS IP), RR53 and RR57 (240 m from CMS IP), TI18 (480 m from ATLAS IP). The potential sites are studied on the basis of (a) expectations for neutrino interaction rates, flavour composition and energy spectrum, (b) predicted backgrounds and in-situ measurements, performed with a nuclear emulsion detector and radiation monitors. TI18 emerges as the most favourable location. A small detector in TI18 could measure, for the first time, the high-energy $\nu$N cross section, and separately for $\tau$ neutrinos, with good precision, already with 300 fb$^{-1}$ in the LHC Run3.

The i-pipe system is a peculiar structural health monitoring system, based on Fiber Bragg Grating technology, installed on the central beam pipe of the compact Muon solenoid (CMS) experiment at CERN. In this contribution, i-pipe temperature sensors, originally conceived as thermal compensator for the strain sensors, are employed to monitor central beam pipe thermal behavior in correlation with the parameters of the particle beam travelling inside, in order to directly measure possible Beam RF induced heating effect. The i-pipe system turned out to be capable of monitoring, directly and without interference, the parameters of the particle beam circulating in the LHC ring. Hence, the results presented in this work pave the way to the use of the i-pipe as monitoring system of an accelerated high energy particle beam.

In this contribution we present results concerning the very first application of fiber optic sensors (FOSs) for relative humidity (RH) monitoring in high radiations environments. After a few years of investigations at CERN in Geneva, since December 2013 our multidisciplinary research group has successfully installed 72 thermo-hygrometers based on Fiber Bragg Grating (FBG) technology, organized in multi-points arrays, in cold areas of the Tracker Bulkhead of the Compact Muon Solenoid (CMS) experiment, where hundreds of electrical connectors are housed and thousands of services, including many cold pipes, cross the volumes through them. In such a complicated environment, a constant hygrometric monitoring is vital, in order to avoid dangerous phenomena of condensation. The collected results in the last year of operation of the proposed sensors are effective and reliable, with temperature, relative humidity and dew point temperature measurements from the FBG-based devices in full agreement with the readings of conventional sensors, temporarily present in the detector. However, experience in operation has shown some limitations of this technology, which are fully detailed in the last section of the paper.

Triple-GEM detector technology was recently selected by CMS for a part of the upgrade of its forward muon detector system as GEM detectors provide a stable operation in the high radiation environment expected during the future High-Luminosity phase of the Large Hadron Collider (HL-LHC). In a first step, GEM chambers (detectors) will be installed in the innermost muon endcap station in the $1.6<\left|\eta\right|<2.2$ pseudo-rapidity region, mainly to control level-1 muon trigger rates after the second LHC Long Shutdown. These new chambers will add redundancy to the muon system in the $\eta$-region where the background rates are high, and the bending of the muon trajectories due to the CMS magnetic field is small. A novel construction technique for such chambers has been developed in such a way where foils are mounted onto a single stack and then uniformly stretched mechanically, avoiding the use of spacers and glue inside the active gas volume. We describe the layout, the stretching mechanism and the overall assembly technique of such GEM chambers.

In this paper we describe the main characteristics and experimental results, recorded in more than four years of data acquisition, of a temperature and strain monitoring system, called i-pipe, based on Fiber Bragg Grating (FBG) sensors arrays applied for the first time to a sector of the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN): the central beam pipe (BP) of the Compact Muon Solenoid (CMS). The monitoring system, consisting of four arrays of 16 FBG sensors each, as better described in the text, is placed on four directives of the LHC section that passes inside the CMS experiment, namely the CMS central BP. The mechanical complexity of the central BP structure is described and the monitoring results of its thermal conditions and online unpredictable mechanical deformations are discussed in this paper. In spite of the harsh working conditions this monitoring system is operational since 2015 continuously (24/7) and the data collected are a confirmation of its reliability. This FBG sensors system represents the ideal solution to realize an accurate and robust sensing system to be used in harsh environments, like the CMS experimental facility and all the other High Energy Physics experimental infrastructures.

The Compact Muon Solenoid (CMS) experiment prepares its Phase-2 upgrade for the high-luminosity era of the LHC operation (HL-LHC). Due to the increase of occupancy, trigger latency and rates, the full electronics of the CMS Drift Tube (DT) chambers will need to be replaced. In the new design, the time bin for the digitization of the chamber signals will be of around 1 ns, and the totality of the signals will be forwarded asynchronously to the service cavern at full resolution. The new backend system will be in charge of building the trigger primitives of each chamber. These trigger primitives contain the information at chamber level about the muon candidates position, direction, and collision time, and are used as input in the L1 CMS trigger. The added functionalities will improve the robustness of the system against ageing. An algorithm based on analytical solutions for reconstructing the DT trigger primitives, called Analytical Method, has been implemented both as a software C++ emulator and in firmware. Its performance has been estimated using the software emulator with simulated and real data samples, and through hardware implementation tests. Measured efficiencies are 96 to 98% for all qualities and time and spatial resolutions are close to the ultimate performance of the DT chambers. A prototype chain of the HL-LHC electronics using the Analytical Method for trigger primitive generation has been installed during Long Shutdown 2 of the LHC and operated in CMS cosmic data taking campaigns in 2020 and 2021. Results from this validation step, the so-called Slice Test, are presented.

In this work, experimental tests of a full analog fiber optic monitoring system are reported. The proposed concept is conceived to satisfy the constrains imposed to be used for safety application, in terms of robustness and reliability, due to full passive optical devices and an analog-based circuitry. Moreover, it is compatible with the stringent requirements imposed by the Detector Safety System (DSS) of the Compact Muon Solenoid (CMS) experiment at CERN. From the optical side, the main device is the Arrayed Waveguide Grating (AWG), with the aim to filter and address the optical signal through a determined output channel, that is then transduced in electrical by means of a photodiode. From the electronic side, the designed board has the purpose to manipulate the signal in order to have an increasing monotone output current, in the range 4-20 mA, standard widely employed in safety system environment. In this way, the circuit gain can be set in order to match the value to the physical quantity under monitoring threshold. To give proof of its characteristics, the system is subjected to many test led at CERN, in which two Fiber Bragg Grating (FBG) sensors are under test into a custom climate box. Step temperature variation, as well as fast oscillating test and long term stability measurement are reported, confirming its key strength and field-validating it.

In the field of accelerator physics it is crucial to account for heating caused by the passage of high intensity beams into accelerator components. This phenomenon is known as Radio Frequency (RF) Beam Induced Heating (BIH) and requires, other than an accurate design stage, to constantly monitor temperature-related parameters during the accelerator operations. This enables to warn for critical malfunctions and to prevent possible damages. Monitoring needs to meet various requirements, such as multiplexing capabilities, distributed sensing possibilities, and robustness in harsh environments. Fiber Bragg Grating sensors (FBGs) have been proven to be an ideal solution that meets all these requirements. This study aims to validate the use of FBGs for direct measurement of RF BIH. A section of the beam pipe in the CERN Large Hadron Collider was modeled in terms of impedance, and the resulting RF BIH was computed based on the traveling beam. The results of the numerical simulation were compared with experimental data obtained by FBGs installed along the beam pipe. The analysis shows that FBGs can be a valuable beam diagnostic tool for monitoring accelerated high energy particle beams by measuring RF BIH and may provide useful insights for improving the design and operation of future accelerators. The study highlights the significant advancements of FBG technology in direct temperature measurement and assessment of RF BIH and serves as a promising solution for mitigating RF BIH in the demanding environment of particle accelerators.

Abstract We discuss an experiment to investigate neutrino physics at the LHC, with emphasis on tau flavour. As described in our previous paper Beni et al (2019 J. Phys. G: Nucl. Part. Phys. 46 115008), the detector can be installed in the decommissioned TI18 tunnel, ≈480 m downstream the ATLAS cavern, after the first bending dipoles of the LHC arc. The detector intercepts the intense neutrino flux, generated by the LHC beams colliding in IP1, at large pseudorapidity η , where neutrino energies can exceed a TeV. This paper focuses on exploring the neutrino pseudorapity versus energy phase space available in TI18 in order to optimize the detector location and acceptance for neutrinos originating at the pp interaction point, in contrast to neutrinos from pion and kaon decays. The studies are based on the comparison of simulated pp collisions at <?CDATA $\sqrt{s}=$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msqrt> <mml:mrow> <mml:mi>s</mml:mi> </mml:mrow> </mml:msqrt> <mml:mo>=</mml:mo> </mml:math> 13 TeV: PYTHIA events of heavy quark (c and b) production, compared to DPMJET minimum bias events (including charm) with produced particles traced through realistic LHC optics with FLUKA. Our studies favour a configuration where the detector is positioned off the beam axis, slightly above the ideal prolongation of the LHC beam from the straight section, covering 7.4 &lt; η &lt; 9.2. In this configuration, the flux at high energies (0.5–1.5 TeV and beyond) is found to be dominated by neutrinos originating directly from IP1, mostly from charm decays, of which ≈50% are electron neutrinos and ≈5% are tau neutrinos. The contribution of pion and kaon decays to the muon neutrino flux is found small at those high energies. With 150 fb −1 of delivered LHC luminosity in Run 3 the experiment can record a few thousand very high energy neutrino charged current (CC) interactions and over 50 tau neutrino CC events. These events provide useful information in view of a high statistics experiment at HL–LHC. The electron and muon neutrino samples can extend the knowledge of the charm PDF to a new region of x , which is dominated by theory uncertainties. The tau neutrino sample can provide first experience on reconstruction of tau neutrino events in a very boosted regime.

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.

In this paper, the results of the long-term temperature monitoring of the compact muon solenoid experiment (CMS) at CERN are shown. The measurements were carried out by means of a system based on fiber Bragg grating (FBG) sensors in wavelength-division multiplexing (WDM). Due to the harsh working conditions at the CMS, the FBG sensor represents the ideal candidate to realize a reliable and accurate sensing system. The sensing principles of the FBG sensor and its temperature characteristics are introduced. A temperature monitoring system based on FBG for high-energy physics applications is designed and installed. The sensing system was used successfully last year in monitoring the temperature of CMS bulkhead. The reported results show good reliability and high accuracy of the FBG sensing system during the long-time working stage.

Results are presented on the activity carried out by our research group, in collaboration with the SME Optosmart s.r.l. (an Italian spin-off company), on the application of Fiber Optic Sensor (FOS) techniques to monitor high-energy physics (HEP) detectors. Assuming that Fiber Bragg Grating sensors (FBGs) radiation hardness has been deeply studied for other field of application, we have applied the FBG technology to the HEP research domain. We present here the experimental evidences of the solid possibility to use such a class of sensors also in HEP detector very complex environmental side conditions. In particular we present more than one year data results of FBG measurements in the Compact Muon Solenoid (CMS) experiment set up at the CERN, where we have monitored temperatures (within CMS core) and strains in different locations by using FBG sensors during the detector operation with the Large Hadron Collider (LHC) collisions and high magnetic field. FOS data and FOS readout system stability and reliability is demonstrated, with continuous 24/24 h 7/7d data taking under severe and complex side conditions.

This contribution introduces a new type of Micropattern Gaseous Detector, the Fast Timing Micropattern (FTM) detector, utilizing fully Resistive WELL structures. The structure of the prototype will be described in detail and the results of the characterization study performed with an X-ray gun will be presented, together with the first results on time resolution based on data collected with muon/pion test beams.

This document describes results obtained from the Link alignment system data recorded during the Compact Muon Solenoid (CMS) Magnet Test. A brief description of the system is followed by a discussion of the detected relative displacements (from micrometres to centimetres) between detector elements and rotations of detector structures (from microradians to milliradians). Observed displacements are studied as functions of the magnetic field intensity. In addition, the reconstructed positions of active element sensors are compared to their positions as measured by photogrammetry and the reconstructed motions due to the magnetic field strength are described.

The results of structural and thermal monitoring of the Compact Muon Solenoid (CMS) experiment in the underground site at CERN will be reported. The measurements are carried out by means of Fiber Bragg Grating sensor arrays installed on the CMS detector, from the inner to the outer regions. This fiber optic monitoring system represents the ideal solution to secure a reliable and accurate sensing system to be used 24/7 in the harsh environment at CERN

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. Following an extensive R&D program, CMS has identified triple-foil gas electron multiplier (GEM) detectors as a solution for the first muon station in the region 1.6<|η|<2.2, while continuing R&D is ongoing for additional regions.

The CMS Collaboration has been developing large-area triple-gas electron multiplier (GEM) detectors to be installed in the muon Endcap regions of the CMS experiment in 2019 to maintain forward muon trigger and tracking performance at the High-Luminosity upgrade of the Large Hadron Collider (LHC); 10 preproduction detectors were built at CERN to commission the first assembly line and the quality controls (QCs). These were installed in the CMS detector in early 2017 and participated in the 2017 LHC run. The collaboration has prepared several additional assembly and QC lines for distributed mass production of 160 GEM detectors at various sites worldwide. In 2017, these additional production sites have optimized construction techniques and QC procedures and validated them against common specifications by constructing additional preproduction detectors. Using the specific experience from one production site as an example, we discuss how the QCs make use of independent hardware and trained personnel to ensure fast and reliable production. Preliminary results on the construction status of CMS GEM detectors are presented with details of the assembly sites involvement.

XSEN (Cross Section of Energetic Neutrinos) is a small experiment designed to study, for the first time, neutrino-nucleon interactions (including the tau flavour) in the 0.5-1 TeV neutrino energy range. The detector will be installed in the decommissioned TI18 tunnel and uses nuclear emulsions. Its simplicity allows construction and installation before the LHC Run 3, 2021-2023; with 150/fb in Run3, the experiment can record up to two thousand neutrino interactions, and up to a hundred tau neutrino events. The XSEN detector intercepts the intense neutrino flux, generated by the LHC beams colliding in IP1, at large pseudo-rapidities, where neutrino energies can exceed the TeV. Since the neutrino-N interaction cross section grows almost linearly with energy, the detector can be light and still collect a considerable sample of neutrino interactions. In our proposal, the detector weighs less than 3 tons. It is lying slightly above the ideal prolongation of the LHC beam from the straight section; this configuration, off the beam axis, although very close to it, enhances the contribution of neutrinos from c and b decays, and consequently of tau neutrinos. The detector fits in the TI18 tunnel without modifications. We plan for a demonstrator experiment in 2021 with a small detector of about 0.5 tons; with 25/fb, nearly a hundred interactions of neutrinos of about 1 TeV can be recorded. The aim of this pilot run is a good in-situ characterisation of the machine-generated backgrounds, an experimental verification of the systematic uncertainties and efficiencies, and a tuning of the emulsion analysis infrastructure and efficiency. This Letter provides an overview of the experiment motivations, location, design constraints, technology choice, and operation.

The CMS drift tubes (DT) muon detector, built for withstanding the LHC expected integrated and instantaneous luminosities, will be used also in the High Luminosity LHC (HL-LHC) at a 5 times larger instantaneous luminosity and, consequently, much higher levels of radiation, reaching about 10 times the LHC integrated luminosity. Initial irradiation tests of a spare DT chamber at the CERN gamma irradiation facility (GIF++), at large (∼ O(100)) acceleration factor, showed ageing effects resulting in a degradation of the DT cell performance. However, full CMS simulations have shown almost no impact in the muon reconstruction efficiency over the full barrel acceptance and for the full integrated luminosity. A second spare DT chamber was moved inside the GIF++ bunker in October 2017. The chamber was being irradiated at lower acceleration factors, and only 2 out of the 12 layers of the chamber were switched at working voltage when the radioactive source was active, being the other layers in standby. In this way the other non-aged layers are used as reference and as a precise and unbiased telescope of muon tracks for the efficiency computation of the aged layers of the chamber, when set at working voltage for measurements. An integrated dose equivalent to two times the expected integrated luminosity of the HL-LHC run has been absorbed by this second spare DT chamber and the final impact on the muon reconstruction efficiency is under study. Direct inspection of some extracted aged anode wires presented a melted resistive deposition of materials. Investigation on the outgassing of cell materials and of the gas components used at the GIF++ are underway. Strategies to mitigate the ageing effects are also being developed. From the long irradiation measurements of the second spare DT chamber, the effects of radiation in the performance of the DTs expected during the HL-LHC run will be presented.

Magnet Cycles and Stability Periods of the CMS Experiment are studied with the Alignment Link System data recorded along the 2008–2013 years of operation. The motions of the mechanical structures due to the magnetic field forces are studied and the mechanical stability of the detector during the physics data taking periods is verified.

A novel approach which uses Fiber Bragg Grating (FBG) sensors has been utilized to assess and monitor the flatness of Gaseous Electron Multipliers (GEM) foils. The setup layout and preliminary results are presented.

In this paper, the results of the temperature and strain monitoring of the central beam pipe of the Compact Muon Solenoid Experiment (CMS) at CERN are presented. The measurements are carried out by means of a system of Fiber Bragg Grating (FBG) sensor arrays glued on the central Beam Pipe of CMS. The system consisting of FBG sensors represents the ideal solution to manufacture a reliable and accurate sensing system to be used 24/7 in the harsh environment in CMS. The sensing principles of the FBG sensor and its temperature characteristics are introduced. First temperature and strain measurements data are presented. They were recorded during last period of CMS maintenance and first period of LHC collision started in April 2015.

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/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 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/CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> (70/30) and Ar/CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> /CF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> (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.

This paper provides an extensive overview of more than a decade of continuous data collected by the Fiber Optic Sensing for CMS (FOS4CMS) network, featuring over 1000 Fiber Bragg Grating (FBG) sensors. These FBG sensors have been instrumental in monitoring temperature and strain within the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC). Their strategic placement allowed for observation of crucial components, including the central beam pipe, silicon tracker, RPC muon detectors, and the underground cavern. Operational since 2009, the monitoring system underwent expansions during LHC Long Shutdowns (LS1 and LS2) and upgrades for LHC Run3. Leveraging Wavelength Division Multiplexing, the FBG sensors demonstrated reliability, seamlessly integrating into the CMS Detector Control System. In summary, the presented data robustly affirm the resilience of FBG sensors in the challenging High Energy Physics environment, with the FOS4CMS system's uninterrupted 24/7 operation over a decade marking a significant milestone in the successful application of FBG technology within the CMS experiment at CERN.

Particle accelerators, such as the Large Hadron Collider (LHC) at CERN, are planning to increase the intensity of circulating particle beams. However, this upgrade faces challenges due to beam-induced heating that can lead to operational issues and component damage. To address this, suitable monitoring systems are required. Fiber Optic Sensing using Fiber Bragg Gratings (FBGs) has gained popularity in the High Energy Physics domain. This study focuses on iPipe, a monitoring system based on FBGs installed in the Compact Muon Solenoid experiment since 2015. FBG sensors offer advantages such as immunity to optoelectronic noise, intensity modulation, and radiation-induced losses. The iPipe system was recently upgraded and is currently acquiring data during LHC Run 3. The initial analysis of this data is presented in this paper.

A study of the time required for the CMS detector to reach structural equilibrium once the magnetic field is ramped to its operational value of 3.8 T is presented. In addition, the results from a stability monitoring at 3.8 T over an eight-month period are given.

The CMS experiment at LHC will upgrade its forward muon spectrometer by incorporating Triple-GEM detectors. This upgrade referred to as GEM Endcap (GE1/1), consists of adding two back-to-back Triple-GEM detectors in front of the existing Cathode Strip Chambers (CSC) in the innermost ring of the endcap muon spectrometer. Before the full installation of 144 detectors in 2019–2020, CMS will first install ten single chamber prototypes during the early 2017. This pre-installation is referred as the slice test. These ten detectors will be read-out by VFAT2 chips [1]. On-detector there is also a FPGA mezzanine card which sends VFAT2 data optically to the μTCA back-end electronics. The correct and safe operation of the GEM system requires a sophisticated and powerful online Detector Control System, able to monitor and control many heterogeneous hardware devices. The DCS system developed for the slice test has been tested with CMS Triple-GEM detectors in the laboratory. In this paper we describe the newly developed DCS system and present the first results obtained in the GEM assembly and quality assurance laboratory.

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 m 2 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.

For the High Luminosity LHC CMS is planning to install new large size Triple-GEM detectors, equipped with a new readout system in the forward region of its muon system (1.5<|η|<2.2). In this note we report on the status of the project, the main achievements regarding the detectors as well as the electronics and readout system.

The CMS Collaboration plans to equip the very forward muon system with triple-GEM detectors that can withstand the environment of the High-Luminosity LHC. This project is at the final stages of R&amp;D and moving to production. An unprecedented large area of several 100 m 2 are to be instrumented with GEM detectors which will be produced in six different sites around the world. A common construction and quality control procedure is required to ensure the performance of each detector. The quality control steps will include optical inspection, cleaning and baking of all materials and parts used to build the detector, leakage current tests of the GEM foils, high voltage tests, gas leak tests of the chambers and monitoring pressure drop vs. time, gain calibration to know the optimal operation region of the detector, gain uniformity tests, and studying the efficiency, noise and tracking performance of the detectors in a cosmic stand using scintillators.

The central feature of the CMS Link alignment system is a network of Amorphous Silicon Position Detectors distributed throughout the muon spectrometer that are connected by multiple laser lines. The data collected during the years from 2008 to 2015 is presented confirming an outstanding performance of the photo sensors during more than seven years of operation. Details of the photo sensor readout of the laser signals are presented. The mechanical motions of the CMS detector are monitored using these photosensors and good agreement with distance sensors is obtained.

During the High Luminosity LHC, the Drift Tube chambers installed in the CMS detector need to operate with an integrated dose ten times higher than expected at the LHC due to the increase in integrated luminosity from 300 fb-1 to 3000 fb-1. Irradiations have been performed to assess the performance of the detector under such conditions and to characterize the radiation aging of the detector. The presented analysis focuses on the behaviour of the high voltage currents and the dose measurements needed to extrapolate the results to High Luminosity conditions, using data from the photon irradiation campaign at GIF++ in 2016 as well as the efficiency analysis from the irradiation campaign started in 2017. Although the single-wire loss of high voltage gain observed of 70% is very high, the muon reconstruction efficiency is expected to decrease less than 20% during the full duration of High Luminosity LHC in the areas under highest irradiation.

The World Year of Physics offers an opportunity to amuse secondary school pupils by experiments that they can perform themselves. The experiment described in this article enables them to visualize the invisible world of nuclear particles. The applied detector is particularly suited for classroom experiments.

During the future LHC upgrade planned in 2018, the forward endcap region of the CMS muon spectrometer will be upgraded with GEM chambers. GEM technology is able to withstand the radiation environment expected in the forward region. The GE1/1 station will be included in the muon L1 trigger, allowing to keep low p(T) threshold even at high luminosity. Moreover, it will bring detection redundancy in the most critical part of the CMS muon system, along with benefits to muon reconstruction performance.

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

In recent years various educational activities have been pursued in Hungary with the aim to raise the interest of high school students in natural sciences, and especially in physics. This brief summary will present some of the key projects of broader interest for the scientific community.

The Compact Muon Solenoid (CMS) detector installed at the CERN Large Hadron Collider (LHC) has an extensive muon system which provides information simultaneously for identification, track reconstruction and triggering of muons. As a consequence of the extreme particle rate and high integrated charge, the essentiality to upgrade the LHC has given rise to the High Luminosity phase of the LHC (HL-LHC) project so that the CMS muon system will be upgraded with superior technological challenges. The CMS GEM collaboration offers a solution to equip the high-eta region of the muon system for Phase 2 (after the year 2017) with large-area triple-layer Gas Electron Multiplier (GEM) detectors, since GEMs have the ability to provide robust and redundant tracking and triggering functions with an excellent spatial resolution of order 100 micron and a high particle rate capability, with a close to 100% detection efficiency. In this contribution, the present status of the triple-GEM project will be reviewed, and the significant achievements from the start of the R&D in 2009 will be emphasized.

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.

Advances in information and communications technologies (ICTs) have given rise to innovative uses of web-based video tools for global communication, enhancing the impact of large research facilities,including their outreach and education programmes.As an example, the Virtual Visits programmes developed by the ATLAS and CMS collaborations at CERN, use videoconferencing to communicate with schools and remote events around the globe.The goal of these programmes is to enable the public, especially young people, to become engaged in and understand the field of particle physics through direct dialogue between ATLAS/CMS scientists and remote audiences.

For the LHC High Luminosity phase (HL-LHC) the CMS GEM Collaboration is planning to install new large size triple-GEM detectors in the forward region of the muon system (1.5<|η|<2.2) of the CMS detector.The muon reconstruction with triple-GEM chambers information included have been successfully integrated in the official CMS software, allowing physics studies to be carried out.The new sub-detector will be able to cope the extreme particle rates expected in this region along with a high spatial resolution.The resulting benefit in terms of triggering and tracking capabilities has been studied: the expected improvement in the performance of the muon identification and track reconstruction as well as the expected improvement coming from the lowering of the muon p T trigger tresholds will be presented.The contribution will review the status of the CMS upgrade project with the usage of GEM detector, discussing the trigger, the muon reconstruction performance and the impact on the physics analyses.

In the conference poster the Sensors for CMS (S4CMS) project is presented. The main goal is to group geographically the existing sensor data in different CMS regions and to make them accessible to the entire CMS community in an easy and direct way. All these data are publically available from different subdetectors or technical support groups. S4CMS project is written in PVSS (ProzessVisualisierungs und Steuerungs System [Process Visualisierungs und Steuerungs System, ETM. http://www.etm.at]) platform, allowing to connect easily different sensor data and the CMS Detector Control System [R. Arcidiacono et al, CMS DCS design concepts, ICALEPCS 2005, Switzerland, Geneva, 2005]. S4CMS software is able to visualize different types of sensors in standardized way, providing also documentation about sensor commercial supplier and reference data sheet. Moreover S4CMS allows to make easy correlations between different types of sensors from different subdetectors. In the first version of S4CMS project, sensor data are grouped in different 2D geographical region views called: Muon, UXC, Vac tank, Beam pipe, HF platform. The 3D geographical region view and the subsystem correlation option are foreseen in future versions. The access to this tool is available primarily in the P5 control room at technical shifters desk as well as in remote mode through the terminal server of the CMS experiment.

After briefly explaining the need for a precise muon chamber alignment, the different muon alignment systems implemented at CMS are described.Due to the tight spatial confinement and challenging large radiation and high magnetic field environment, unique alignment systems had to be developed that handle separately the Barrel and the Endcap regions.A third subsystem, called Link, connects these two together and to the Tracker in a common reference frame.The aligned chamber geometry obtained from the Hardware-based muon alignment is validated by comparisons with photogrammetry information and by studies of residuals of muon tracks extrapolated between chambers.Stability studies, for which the hardware systems are particularly well suited, are also discussed.Alignment methods based on tracks are also described.Muons from cosmic rays and from collisions are used to align the chambers relative to the inner tracker.In addition, beam halo muon tracks traversing overlapping endcap chambers are used for internal endcap alignment.A comparison between the track-based and hardware-based results is given, together with an explanation of the advantages and disadvantages of the different alignment strategies.

The CMS Muon Barrel Alignment system uses cameras mounted on 36 rigid MAB structures to monitor DT positions. During the 2010 and 2011 data-taking periods, 4 such MABs became inoperative. This study shows that the resulting loss of information does not cause a significant degradation of the reconstructed DT positions.

During the past years our group has built, calibrated, and finally installed all the components of the Muon Barrel Alignment System for the CMS experiment. This paper covers the results of the hardware commissioning, the full system setup and the connection to the CMS Detector Control System (DCS). The step-by-step operation of the system is discussed: from collecting the analog video signals and preprocessing the observed LED images, through controlling the front-end PCs, to forming the measurement results for the CMS DCS. The first measurement results and the initial experiences of the communication with the DCS are also discussed.

In this study, a novel monitoring system based on fiber optic technology is investigated. It is based on a full analog electronic circuitry and full passive optical devices, allowing to increase its robustness and reliability, without losing in terms of measurement accuracy. Due to these peculiarities, the conceived system satisfies the constrains imposed by the detector safety systems, a dedicated section in charge to control and handle anything is related to the equipment protection of experimental apparatus like the Large Hadron Collider (LHC) experiment at CERN. Experimental tests of the proposed system have been conducted in laboratory environment and the results, in terms of temperature variation, are shown. Two Fiber Bragg Grating sensors under test are employed, monitoring a deviation of 20°C with 1°C step, simulating a possible scenario in which the system will be employed in the next months.

In the last year as part of the first test of the CMS experiment at CERN [1] called Magnet Test and Cosmic Challenge (MTCC) about 25% of the barrel muon position monitoring system was built and operated. The configuration enabled us to test all the elements of the system and its function in real conditions. The correct operation of the system has been demonstrated. About 500 full measurement cycles have been recorded. In the paper the setup –including the read-out and control is described and the first preliminary results are presented.

In order to be able to match correctly the track elements produced by a muon in the Tracker and the Muon System of the CMS experiment [1] the mutual alignment precision between the Tracker and the Barrel Muon System must be no worse than 100-400 micrometers depending on the radial distance of the muon chambers from the Tracker. To fulfill this requirement an alignment system had to be designed. This system contains subsystems for determining the positions of the barrel and endcap chambers while a third one connects these two to the Tracker. Since the Barrel muon chambers are embedded into the magnet yoke of the experiment a nonconventional alignment method had to be developed. In this paper we restrict ourselves to the Barrel Alignment System and the calibration methods of its components. I. THE BARREL MUON ALIGNMENT SYSTEM The CMS Barrel Muon Alignment System (Fig. 1) is based on an optical network of LED light sources and videocameras. The full system contains very large number of cameras (approx. 600 pcs) and LEDs (approx. 10000 pcs). Overwhelming part of these LEDs are mounted on the 250 barrel muon chambers while the cameras observing these LEDs are mounted on rigid structures called MABs (Module for Alignment of the Barrel). The MABs (36 pieces altogether) are fixed on the iron yoke of the magnet. Furthermore, there are about 300 LEDs and 100 cameras making direct connections between the MABs (called diagonal connections). Finally there are 6 long carbon-fiber bars located inside the barrel muon system containing in total 144 LED light sources allowing direct measurement of the Z coordinates of 24 MABs (where Z direction in the experiment corresponds to the direction of the proton beam path). The results of individual measurements are the positions of the centroids of the images of the LEDs measured by the cameras. In order to be able to reconstruct the positions of the muon chambers additional data -in addition to the measured centroidsis required. These are the parameters of the cameras (magnification, and tilt angles of the sensor with respect to the optical axis of the camera, sensitivity and homogeneity of the video-sensors of the cameras) and the positions of the LEDs on their holders. Also, the positions of the cameras and the LED holders in their embedding objects (muon chambers, MABs, Z-bars) are also needed. These additional data are obtained by the calibration of the elements. Figure 1. CMS Barrel Muon Alignment scheme II. CALIBRATION OF THE COMPONENTS The main requirement on the muon chamber alignment precision is in the range of 100-400 microns. Since this value depends also on the calibration precision of the components, the calibration methods had to be established such that the resulted precision of the full system could meet the above mentioned requirements. The individual calibration steps of the light source-related objects are the LED holder calibration and the barrel muon chamber alignment calibration, while calibration steps of the camera related objects are the camera quality control, the camera calibration and the MAB calibration. A. Light source related objects As it is mentioned above the basic components of the Barrel Muon Alignment System are the LEDs and the cameras. Individual LEDs are grouped into mechanical structures called LED holders containing 10 (for DT chambers), 3 (diagonal LED holders) or 6 (Z-LED holders) LEDs according to the measurement type. During the calibration process positions of the LED centroids in the frame of the LED holder are determined. The optical network requires most of the LED holders to be observed from both sides. This can be solved by introducing an auxiliary frame of reference which can be seen from both sides. Technically, this is a calibration tool containing multimode optical fibers illuminated by noncoherent light sources and shining into both directions. Positions of these light sources are measured in a high precision metrology lab and produce light distributions similar to those of the LEDs to be measured. Since the light spots are observed by cameras there was a requirement to exclude geometrical distortions and the error on centroid calculation caused by the un-even gain on the sensor surface. This has been solved by mounting the calibration tool (and therefore the LED holders) on a precise two-dimensional moving table and by constructing a successive method for moving all the centroids to a predefined position on the sensor surfaces. Therefore LED positions correspond to the position readouts of the moving table. Figure 2. Calibration bench for the LED holders. As the amount of LED holders is very large (>1200 pieces) a highly automated measurement method had to be developed. Both the successive centroid measurements and the control of the moving table and the LED holders are computerized. The operator only has to change the LED holders, identify it and start the measurement. The successive status then can be monitored on the computer console. Also due to the large number of LED holders an effective way of data handling and storage had to be developed. For such a large number of data (five complete measurements of all the LED holders ~ 100 k lines of raw data + 20 k lines of analyzed data) the use of a commercially available database solution is inevitable. Our team decided to use MySQL because it supports all the programming languages used in this calibration process under all operating systems. This database server also had an advantage because its installation requires only a moderate disk space and it is also freely available for research purposes. For data security reasons measurements are recorded as ASCII files which are automatically uploaded as the measurement finishes. Therefore one can assure to have two identical copies of the raw data and in case of critical failure of the database server data can be recuperated by using the same method used for synchronizing the database to the ASCII files. However, storage of data in a relational database provides a very easy way to compare the individual measurements therefore pinpointing any measurement errors based on statistical methods. This statistical analysis and the data recuperation are done by web-based Perl scripts allowing the access to the data from virtually everywhere without the need for special data handling software. Calibration methods of the diagonal and Z-LED holders are very similar to that of those ones described above. Figure 3. Data flow during the LED holder calibration [5] The main goal of the alignment system is to locate the anode wires of the muon chambers with respect to the Tracker. Muon chambers have a construction which doesn’t allow the observation of their anode wires after construction. This construction doesn’t allow either to determine the LED holder’s position with respect to the wires during chamber building. To overcome this problem the following technology has been developed: 1. During construction position of every anode wire (approx. 400 per chamber) is measured during the construction with respect to mechanical reference objects known as corner blocks mounted on each corner of a muon chamber’s Super Layer [2] (4 pieces per Super Layer). Since a muon chamber consists of two or three Super Layers depending on its type, a muon chamber can have eight or twelve corner blocks in total. These corner blocks serve as position references. 2. Since the position measurement of the LED holders is based on a centroid measurement while positions of the corner blocks can be determined by standard survey techniques (photogrammetry) an additional calibration bench had to be built. Here the corner blocks can be located by photogrammetry and the LED holders mounted on the chambers can be measured by cameras with pre-calibrated (known) positions with respect to the calibration bench. For this pre-calibration a specially designed calibration plate containing both optical fiber light sources and target holes for the photogrammetry is used. Internal parameters of these plates could be determined by a metrology laboratory. During the precalibration of the chamber bench these plates are localized by photogrammetry while a simultaneous measurement of the optical fibers has been performed by the cameras. A geometrical reconstruction is able to recuperate both the camera positions and their internal parameters needed for a correct measurement of the LED holders. 3. Applying mathematical transformations the positions of the LED holders can be determined in the chamber’s frame. As a byproduct the localization of all the Super Layers in the chamber’s frame can also be performed. The number of muon chambers to be measured was 264, therefore this calibration step also requires a reliable data handling strategy. Since during LED holder calibration the LED Holder Calibration

To sustain and extend its discovery potential, the Large Hadron Collider (LHC) will undergo a major upgrade in the coming years, referred to as High Luminosity LHC (HLLHC), aimed to increase its instantaneous luminosity, 5 times larger than the designed limit, and, consequently leading to high levels of radiation, with the goal to collect 10 times larger the original designed integrated luminosity. The drift tube chambers (DT) of CMS muon detector system is built to proficiently measure and trigger on muons in the harsh radiation environment expected during the HL-LHC era. Ageing studies are performed at the CERNs gamma ray irradiation facility (GIF++) by measuring the muon hit efficiency of these detectors at various LHC operation conditions. One such irradiation campaign was started in October 2017, when a spare MB2 chamber moved inside the bunker and irradiated at lower acceleration factors. Two out of twelve layers of the DT chamber were operated while being irradiated with the radioactive source and then their muon hit efficiency was calculated in coincidence with other ten layers which were kept on the standby. The chamber absorbed an integrated dose equivalent to two times the expected integrated luminosity of the HL-LHC. Investigation on the outgassing of cell materials and of the gas components used at the GIF++ are underway and strategies to mitigate the aging effects are also being developed. The effect of radiation on the performance of DT chamber and its impact on the overall muon reconstruction efficiency expected during the HL-LHC are presented.

XSEN (Cross Section of Energetic Neutrinos) is a small experiment designed to study, for the first time, neutrino-nucleon interactions (including the tau flavour) in the 0.5-1 TeV neutrino energy range. The detector will be installed in the decommissioned TI18 tunnel and uses nuclear emulsions. Its simplicity allows construction and installation before the LHC Run 3, 2021-2023; with 150/fb in Run3, the experiment can record up to two thousand neutrino interactions, and up to a hundred tau neutrino events. The XSEN detector intercepts the intense neutrino flux, generated by the LHC beams colliding in IP1, at large pseudo-rapidities, where neutrino energies can exceed the TeV. Since the neutrino-N interaction cross section grows almost linearly with energy, the detector can be light and still collect a considerable sample of neutrino interactions. In our proposal, the detector weighs less than 3 tons. It is lying slightly above the ideal prolongation of the LHC beam from the straight section; this configuration, off the beam axis, although very close to it, enhances the contribution of neutrinos from c and b decays, and consequently of tau neutrinos. The detector fits in the TI18 tunnel without modifications. We plan for a demonstrator experiment in 2021 with a small detector of about 0.5 tons; with 25/fb, nearly a hundred interactions of neutrinos of about 1 TeV can be recorded. The aim of this pilot run is a good in-situ characterisation of the machine-generated backgrounds, an experimental verification of the systematic uncertainties and efficiencies, and a tuning of the emulsion analysis infrastructure and efficiency. This Letter provides an overview of the experiment motivations, location, design constraints, technology choice, and operation.

The Muon Barrel Alignment system is based on the precise measurement of LED positions and signals of different sensors located in several predetermined places of the barrel. These data are collected by 36 PC/104 board computers. The board computers are organized in a network and controlled by a workstation, which communicates with the DCS system providing the precise status information of the barrel muon chambers. The aim of this paper is to describe the communication flow, the data hierarchy, the data structure, and the distribution of the tasks among the elements of the system. The first simulation and test results are also discussed.

This document presents an overview of the induced photocurrents in the Amorphous Silicon Position Detectors used in the network of diode lasers and photo sensors of the CMS Link alignment system recorded during its eleven years of operation. After a description of the sensors characteristics, the layout of the sensors network is discussed. The sensors are distributed throughout the muon spectrometer and connected by laser lines. The data used correspond to readout information obtained during some of the physics runs from 2008 to 2018.