G. Mitselmakher

This paper describes the physics case for a new fixed target facility at CERN SPS. The SHiP (search for hidden particles) experiment is intended to hunt for new physics in the largely unexplored domain of very weakly interacting particles with masses below the Fermi scale, inaccessible to the LHC experiments, and to study tau neutrino physics. The same proton beam setup can be used later to look for decays of tau-leptons with lepton flavour number non-conservation, and to search for weakly-interacting sub-GeV dark matter candidates. We discuss the evidence for physics beyond the standard model and describe interactions between new particles and four different portals—scalars, vectors, fermions or axion-like particles. We discuss motivations for different models, manifesting themselves via these interactions, and how they can be probed with the SHiP experiment and present several case studies. The prospects to search for relatively light SUSY and composite particles at SHiP are also discussed. We demonstrate that the SHiP experiment has a unique potential to discover new physics and can directly probe a number of solutions of beyond the standard model puzzles, such as neutrino masses, baryon asymmetry of the Universe, dark matter, and inflation.

We present a method for detection and reconstruction of the gravitational wave (GW) transients with the networks of advanced detectors. Originally designed to search for transients with the initial GW detectors, it uses significantly improved algorithms, which enhance both the low-latency searches with rapid localization of GW events for the electromagnetic follow-up and high confidence detection of a broad range of the transient GW sources. In this paper, we present the analytic framework of the method. Following a short description of the core analysis algorithms, we introduce a novel approach to the reconstruction of the GW polarization from a pattern of detector responses to a GW signal. This polarization pattern is a unique signature of an arbitrary GW signal that can be measured independently from the other source parameters. The polarization measurements enable rapid reconstruction of the GW waveforms, sky localization, and helps identification of the source origin.

We describe a coherent network algorithm for detection and reconstruction of gravitational wave bursts. The algorithm works for two and more arbitrarily aligned detectors and can be used for both all-sky and triggered burst searches. We describe the main components of the algorithm, including the time-frequency analysis in a wavelet domain, construction of the likelihood time-frequency maps, and identification and selection of burst events.

A new general purpose fixed target facility is proposed at the CERN SPS accelerator which is aimed at exploring the domain of hidden particles and make measurements with tau neutrinos. Hidden particles are predicted by a large number of models beyond the Standard Model. The high intensity of the SPS 400~GeV beam allows probing a wide variety of models containing light long-lived exotic particles with masses below ${\cal O}$(10)~GeV/c$^2$, including very weakly interacting low-energy SUSY states. The experimental programme of the proposed facility is capable of being extended in the future, e.g. to include direct searches for Dark Matter and Lepton Flavour Violation.

coherent WaveBurst (cWB) is a highly configurable pipeline designed to detect a broad range of gravitational-wave (GW) transients in the data of the worldwide network of GW detectors. The algorithmic core of cWB is a time–frequency analysis with the Wilson–Daubechies–Meyer wavelets aimed at the identification of GW events without prior knowledge of the signal waveform. cWB has been in active development since 2003 and it has been used to analyze all scientific data collected by the LIGO-Virgo detectors ever since. On September 14, 2015, the cWB low-latency search detected the first gravitational-wave event, GW150914, a merger of two black holes. In 2019, a public open-source version of cWB has been released with GPLv3 license.

We propose a coherent method for detection and reconstruction of gravitational wave signals with a network of interferometric detectors. The method is derived by using the likelihood ratio functional for unknown signal waveforms. In the likelihood analysis, the global maximum of the likelihood ratio over the space of waveforms is used as the detection statistic. We identify a problem with this approach. In the case of an aligned pair of detectors, the detection statistic depends on the cross correlation between the detectors as expected, but this dependence disappears even for infinitesimally small misalignments. We solve the problem by applying constraints on the likelihood functional and obtain a new class of statistics. The resulting method can be applied to data from a network consisting of any number of detectors with arbitrary detector orientations. The method allows us reconstruction of the source coordinates and the waveforms of two polarization components of a gravitational wave. We study the performance of the method with numerical simulations and find the reconstruction of the source coordinates to be more accurate than in the standard likelihood method.

We describe the initial performance of the detector used for the luminosity measurement in the CDF experiment in Run II at the Tevatron. The detector consists of low-mass gaseous Cherenkov counters with high light yield (∼100 photoelectrons) and monitors the process of inelastic pp̄ scattering. It allows for several methods of precise luminosity measurements at peak instantaneous luminosities of 2×1032cm−2s−1, corresponding to an average of six pp̄ interactions per bunch crossing.

Coincident observations with gravitational wave (GW) detectors and other astronomical instruments are in the focus of the experiments with the network of LIGO, Virgo and GEO detectors. They will become a necessary part of the future GW astronomy as the next generation of advanced detectors comes online. The success of such joint observations directly depends on the source localization capabilities of the GW detectors. In this paper we present studies of the sky localization of transient sources with the future advanced detector networks and describe their fundamental properties. By reconstructing sky coordinates of ad hoc signals injected into simulated detector noise we study the accuracy of the source localization and its dependence on the strength of injected signals, waveforms and network configurations.

The time-frequency transforms are important tools for identification of transient events in the output of the gravitational-wave detectors. Produced by the terrestrial and possibly by astrophysical sources, the transient events can be identified as patterns on the time-frequency plane with the excess power above stationary detector noise. In this paper we consider a particular case of the Wilson-Daubechies time-frequency transform for use in the gravitational-wave burst analysis. The presented Wilson-Daubechies basis shares some properties with the Gabor frames, but circumvents the Balian-Low theorem. It also shares similarity with the Meyer wavelet, which is actively used in the gravitational-wave burst analysis. The main advantages of the Wilson-Daubechies transform are the low computational cost, spectral leakage control, flexible structure of the frequency sub-bands, and the existence of the analytic time-delay filters, which are important for localization of the gravitational-wave sources in the sky. These properties of the Wilson-Daubechies transform may prove useful not only in the transient analysis, but also in other areas of the gravitational wave data analysis and detector characterization.

Most of compact binary systems are expected to circularize before the frequency of emitted gravitational waves (GWs) enters the sensitivity band of the ground based interferometric detectors. However, several mechanisms have been proposed for the formation of binary systems, which retain eccentricity throughout their lifetimes. Since no matched-filtering algorithm has been developed to extract continuous GW signals from compact binaries on orbits with low to moderate values of eccentricity, and available algorithms to detect binaries on quasi-circular orbits are sub-optimal to recover these events, in this paper we propose a search method for detection of gravitational waves produced from the coalescences of eccentric binary black holes (eBBH). We study the search sensitivity and the false alarm rates on a segment of data from the second joint science run of LIGO and Virgo detectors, and discuss the implications of the eccentric binary search for the advanced GW detectors.

We address the problem of noise regression in the output of gravitational-wave (GW) interferometers, using data from the physical environmental monitors (PEM). The objective of the regression analysis is to predict environmental noise in the GW channel from the PEM measurements. One of the most promising regression methods is based on the construction of Wiener–Kolmogorov (WK) filters. Using this method, the seismic noise cancellation from the LIGO GW channel has already been performed. In the presented approach the WK method has been extended, incorporating banks of Wiener filters in the time–frequency domain, multi-channel analysis and regulation schemes, which greatly enhance the versatility of the regression analysis. Also we present the first results on regression of the bi-coherent noise in the LIGO data.

The importance of the $H\ensuremath{\rightarrow}ZZ\ensuremath{\rightarrow}4\ensuremath{\ell}$ ``golden'' channel was shown by its major role in the discovery, by the ATLAS and CMS collaborations, of a Higgs-like boson with mass near 125 GeV. We analyze the discrimination power of the matrix element method both for separating the signal from the irreducible $ZZ$ background and for distinguishing various spin and parity hypotheses describing a signal in this channel. We show that the proper treatment of interference effects associated with permutations of identical leptons in the $4e$ and $4\ensuremath{\mu}$ final states plays an important role in achieving the best sensitivity in measuring the properties of the newly discovered boson. We provide a code, mekd, that calculates kinematic discriminants based on the full leading-order matrix elements and which will aid experimentalists and phenomenologists in their continuing studies of the $H\ensuremath{\rightarrow}ZZ\ensuremath{\rightarrow}4\ensuremath{\ell}$ channel.

On May 21, 2019 the Advanced LIGO and Advanced Virgo detectors observed a gravitational-wave transient GW190521, the heaviest binary black-hole merger detected to date with remnant mass of $142\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ that was published recently. This observation is the first strong evidence for the existence of intermediate-mass black holes. The significance of this observation was determined by the coherent waveburst (cWB) search algorithm, which identified GW190521 with minimal assumptions of its source model. In this paper, we show the performance of cWB for the detection of the binary black-hole mergers without use of the signal templates, describe the details of the GW190521 detection, and establish the consistency of the model-agnostic reconstruction of GW190521 by cWB with the theoretical waveform model of a binary black hole.

We present a general procedure for measuring the tensor structure of the coupling of the scalar Higgs-like boson recently discovered at the LHC to two Z bosons, including the effects of interference among different operators. To motivate our concern with this interference, we explore the parameter space of the couplings in the effective theory describing these interactions and illustrate the effects of interference on the differential dilepton mass distributions. Kinematic discriminants for performing coupling measurements that utilize the effects of interference are developed and described. We present projections for the sensitivity of coupling measurements that use these discriminants in future LHC operation in a variety of physics scenarios.

We have built a novel device for precision measurements of luminosity in the CDF experiment at the high pp̄ collision rates expected during Run II. The detector consists of long, conical, gaseous Cherenkov counters that point to the collision region and monitor the average number of inelastic pp̄ interactions by measuring the number of particles, and their arrival time, in each bunch crossing. For these primary particles, using isobutane at atmospheric pressure as a radiator, a large amount of Cherenkov light (∼100 photoelectrons) will be collected, with good amplitude and time resolutions, onto small and efficient PMTs. Suitable amplitude thresholds will be applied to discriminate from non-primary particles and other backgrounds which yield little light in the counters. This detector is expected to reliably perform bunch-by-bunch luminosity measurements at peak instantaneous luminosities of 2×1032 cm−2 s−1 with six interactions per bunch crossing, on average, and respond to a 132 ns bunch spacing.

In this paper we describe the performance of the WaveBurst algorithm which was designed for detection of gravitational wave bursts in interferometric data. The performance of the algorithm was evaluated on the test dataset collected during the second LIGO Scientific run. We have measured the false alarm rate of the algorithm as a function of the threshold and estimated its detection efficiency for simulated burst waveforms.

The detection and estimation of gravitational wave burst signals, with a priori unknown polarization waveforms, requires the use of data from a network of detectors. Maximizing the network likelihood functional over all waveforms and sky positions yields point estimates for them as well as a detection statistic. However, the transformation from the data to estimates can become ill-conditioned over parts of the sky, resulting in significant errors in estimation. We modify the likelihood procedure by introducing a penalty functional which suppresses candidate solutions that display large signal-to-noise ratio (SNR) variability as the source is displaced on the sky. Simulations show that the resulting network analysis method performs significantly better in estimating the sky position of a source. Further, this method can be applied to any network, irrespective of the number or mutual alignment of detectors.

Excess energy method is used in searches of gravitational waves (GWs) produced from sources with poorly modeled characteristics. It identifies GW events by searching for a coincidence appearance of excess energy in a GW detector network. While it is sensitive to a wide range of signal morphologies, the energy outliers can be populated by background noise events (background), thereby reducing the statistical confidence of a true signal. However, if the physics of the source is partially understood, weak model dependent constraints can be imposed to suppress the background. This letter presents a novel idea of using the reconstructed chirp mass along with two goodness of fit parameters for suppressing background when search is focused on GW produced from the compact binary coalescence.

Studies of Cathode Strip Chamber longevity, comparing Ar+CO2 gas mixtures with fractions of 5%, 2%, and 0% CF4, were performed using several small cathode strip prototype chambers. In each trial, a localized source of radiation was used to irradiate up to an accumulated charge of about 300 mC/cm. Additionally, longevity of a uniformly irradiated prototype operating with 2% CF4 was studied at the CERN Gamma Irradiation Facility GIF++. Post-hoc analysis of the chamber electrodes using spectroscopy techniques was also done.

Abstract Studies of cathode strip chamber longevity, comparing Ar+CO $$_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow /> <mml:mn>2</mml:mn> </mml:msub> </mml:math> gas mixtures with fractions of 5%, 2%, and 0% CF $$_4$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow /> <mml:mn>4</mml:mn> </mml:msub> </mml:math> , were performed using several small cathode strip prototype chambers. In each trial, a localized source of radiation was used to irradiate up to an accumulated charge of about 300 mC/cm. Additionally, longevity of a uniformly irradiated prototype operating with 2% CF $$_4$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow /> <mml:mn>4</mml:mn> </mml:msub> </mml:math> was studied at the CERN Gamma Irradiation Facility GIF++. Post-hoc analysis of the chamber electrodes using spectroscopy techniques was also done.

Motivated by the success of the flavour physics programme carried out over the last decade at the Large Hadron Collider (LHC), we characterize in detail the physics potential of its High-Luminosity and High-Energy upgrades in this domain of physics. We document the extraordinary breadth of the HL/HE-LHC programme enabled by a putative Upgrade II of the dedicated flavour physics experiment LHCb and the evolution of the established flavour physics role of the ATLAS and CMS general purpose experiments. We connect the dedicated flavour physics programme to studies of the top quark, Higgs boson, and direct high-$p_T$ searches for new particles and force carriers. We discuss the complementarity of their discovery potential for physics beyond the Standard Model, affirming the necessity to fully exploit the LHC's flavour physics potential throughout its upgrade eras.

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.

This Report summarises the activities of the "SM and Higgs" working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 2-20 May, 2005. On the one hand, we performed a variety of experimental and theoretical studies on standard candles (such as W, Z, and ttbar production), treating them either as proper signals of known physics, or as backgrounds to unknown physics; we also addressed issues relevant to those non-perturbative or semi-perturbative ingredients, such as Parton Density Functions and Underlying Events, whose understanding will be crucial for a proper simulation of the actual events taking place in the detectors. On the other hand, several channels for the production of the Higgs, or involving the Higgs, have been considered in some detail. The report is structured into four main parts. The first one deals with Standard Model physics, except the Higgs. A variety of arguments are treated here, from full simulation of processes constituting a background to Higgs production, to studies of uncertainties due to PDFs and to extrapolations of models for underlying events, from small-$x$ issues to electroweak corrections which may play a role in vector boson physics. The second part of the report treats Higgs physics from the point of view of the signal. In the third part, reviews are presented on the current status of multi-leg, next-to-leading order and of next-to-next-to-leading order QCD computations. Finally, the fourth part deals with the use of Monte Carlos for simulation of LHC physics.

We present a method for detection and reconstruction of gravitational wave signals with a network of interferometric detectors. The method is based on the constraint maximization of the likelihood ratio functional. We discribe the method for the cases of white and colored detector noise.

This Report summarises the activities of the SM and working group for the Workshop Physics at TeV Colliders, Les Houches, France, 2-20 May, 2005. On the one hand, we performed a variety of experimental and theoretical studies on standard candles (such as W, Z, and ttbar production), treating them either as proper signals of known physics, or as backgrounds to unknown physics; we also addressed issues relevant to those non-perturbative or semi-perturbative ingredients, such as Parton Density Functions and Underlying Events, whose understanding will be crucial for a proper simulation of the actual events taking place in the detectors. On the other hand, several channels for the production of the Higgs, or involving the Higgs, have been considered in some detail. The report is structured into four main parts. The first one deals with Standard Model physics, except the Higgs. A variety of arguments are treated here, from full simulation of processes constituting a background to Higgs production, to studies of uncertainties due to PDFs and to extrapolations of models for underlying events, from small-$x$ issues to electroweak corrections which may play a role in vector boson physics. The second part of the report treats Higgs physics from the point of view of the signal. In the third part, reviews are presented on the current status of multi-leg, next-to-leading order and of next-to-next-to-leading order QCD computations. Finally, the fourth part deals with the use of Monte Carlos for simulation of LHC physics.

We describe how to use ZFITTER, a program based on a semi-analytical approach to fermion pair production in e+e- annihilation and Bhabha scattering. A flexible treatment of complete ${\cal O}(α)$ QED corrections, also including higher orders, allows for three calculational {\bf chains} with different realistic sets of restrictions in the photon phase space. {\tt ZFITTER} consists of several {\bf branches} with varying assumptions on the underlying hard scattering process. One includes complete ${\cal O}(α)$ weak loop corrections with a resummation of leading higher-order terms. Alternatively, an ansatz inspired from S-matrix theory, or several model-independent effective Born cross sections may be convoluted. The program calculates cross sections, forward-backward asymmetries, and for $τ$~pair production also the final-state polarization. Various {\bf interfaces} allow fits to be performed with different sets of free parameters.

Compact binary coalescence (CBC) is one of the most promising sources of gravitational waves. These sources are usually searched for with matched filters which require accurate calculation of the GW waveforms and generation of large template banks. We present a complementary search technique based on algorithms used in un-modeled searches. Initially designed for detection of un-modeled bursts, which can span a very large set of waveform morphologies, the search algorithm presented here is constrained for targeted detection of the smaller subset of CBC signals. The constraint is based on the assumption of elliptical polarization for signals received at the detector. We expect that the algorithm is sensitive to CBC signals in a wide range of masses, mass ratios and spin parameters. In preparation for the analysis of data from the fifth LIGO-Virgo science run (S5), we performed preliminary studies of the algorithm on test data. We present the sensitivity of the search to different types of simulated binary black hole waveforms. Also, we discuss how to extend the results of the test run into a search over all of the current LIGO-Virgo data set.

By probing the population of binary black hole (BBH) mergers detected by LIGO-Virgo, we can infer properties about the underlying black hole formation channels. A mechanism known as pair-instability (PI) supernova is expected to prevent the formation of black holes from stellar collapse with mass greater than $\sim 40-65\,M_\odot$ and less than $\sim 120\,M_\odot$. Any BBH merger detected by LIGO-Virgo with a component black hole in this gap, known as the PI mass gap, likely originated from an alternative formation channel. Here, we firmly establish GW190521 as an outlier to the stellar-mass BBH population if the PI mass gap begins at or below $65\, M_{\odot}$. In addition, for a PI lower boundary of $40-50\, M_{\odot}$, we find it unlikely that the remaining distribution of detected BBH events, excluding GW190521, is consistent with the stellar-mass population.

We describe here a novel approach to luminosity measurements for pp̄ collider experiments. We propose to use low-pressure gaseous Cherenkov counters at small angles relative to the beam direction to determine the rate of inelastic pp̄ interactions. With a propotype counter, we measured at a beam test a light yield of over 100 photoelectrons and a timing resolution of better than 50 ps. The CDF collaboration will use a detector based on this technique for luminosity measurements at the upgraded Tevatron collider.

Presented are the main design features of the large Cathode Strip Chambers (CSCs) for the CMS Endcap Muon System as well as the performance results obtained with the two full-scale 3.4×1.5 m2 six-plane prototypes. The prototype performance was within the baseline requirements: (a) higher than 99% efficiency of muon track finding at the trigger level with more than 92% probability for bunch crossing identification and better than 2 mm spatial resolution, and (b) better than 150 μm spatial resolution in off-line.

The "golden" channel, in which the newly-discovered Higgs boson decays to four leptons by means of intermediate vector bosons, is important for determining the properties of the Higgs boson and for searching for subtle new physics effects. Different approaches exist for parametrizing the relevant Higgs couplings in this channel; here we relate the use of pseudo-observables to methods based on specifying the most general amplitude or Lagrangian terms for the $HVV$ interactions. We also provide projections for sensitivity in this channel in several novel scenarios, illustrating the use of pseudo-observables, and analyze the role of kinematic distributions and (ratios of) rates in such $H\to4\ell$ studies.

Aging of CMS muon cathode strip chamber prototypes under sustained irradiation was studied. The tests were performed with three prototypes of different gas seal designs and with three gas mixtures Ar(30%)+CO2(50%)+CF4(20%), Ar(30%)+CO2(70%) and Ar(40%)+CO2(50%)+CF4(10%). The CF4-containing mixtures showed no or little aging for an overall accumulated charge per unit of wire length in excess of 13C/cm. In comparison, the performance deterioration in the Ar–CO2 mixture proved to be very dramatic: the gas gain falls by a factor of 2 for each 0.25C/cm of accumulated charge.

Two CMS production Cathode Strip Chambers were tested for aging effects in a high-radiation environment at the Gamma Irradiation Facility at CERN. The chambers were irradiated over a large area: in total, about 2.1 m2 or 700 m of wire in each chamber. The 40% Ar+50% CO2+10% CF4 gas mixture was provided by an open-loop gas system for one of the chambers and by a closed-loop re-circulating gas system for the other. After an accumulation of 0.3–0.4 C/cm of a wire, equivalent to about 30–50 years of operation at peak LHC luminosity, no significant changes in gas gain, chamber efficiency and wire signal noise were observed for either of the two chambers. The only consistent signs of aging were a small increase in dark current from ∼2 to ∼10 nA per plane of 600 wires and a decrease of strip-to-strip resistance from 1000 to 10–100 GΩ. Disassembly of the chambers revealed deposits on the cathode planes, while the anode wires remained fairly clean.

A simple network of comparators applied to the strip signals of a cathode strip chamber allows quick hit localization to within a halfstrip width, or ± a quarter-strip. A six-plane chamber with 6.4 mm wide strips was tested in a high-energy muon beam. The chamber was placed behind a 30 cm thick iron block. We show that patterns of hits localized to within a halfstrip allowed us to identify 300 GeV/c muon tracks with 99% probability and 0.7 mm spatial resolution in the presence of bremsstrahlung radiation. This technique of finding muon tracks will be used in the cathode strip chambers of the CMS Endcap Muon System.

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.

coherent WaveBurst (cWB) is a highly configurable pipeline designed to detect a broad range of gravitational-wave (GW) transients in the data of the worldwide network of GW detectors. The algorithmic core of cWB is a time-frequency analysis with the Wilson-Daubechies-Meyer wavelets aimed at the identification of GW events without prior knowledge of the signal waveform. cWB has been in active development since 2003 and it has been used to analyze all scientific data collected by the LIGO-Virgo detectors ever since. On September 14, 2015, the cWB low-latency search detected the first gravitational-wave event, GW150914, a merger of two black holes. In 2019, a public open-source version of cWB has been released with GPLv3 license.

This is the TeV4LHC report of the Physics Landscapes Working Group, focused on facilitating the start-up of physics explorations at the LHC by using the experience gained at the Tevatron. We present experimental and theoretical results that can be employed to probe various scenarios for physics beyond the Standard Model.

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.

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.

In the Compact Muon Solenoid (CMS) experiment, muon detection in the forward direction is accomplished by cathode strip chambers (CSC). These detectors identify muons, provide a fast muon trigger, and give a precise measurement of the muon trajectory. There are 468 six-plane CSCs in the system. The efficiency of finding muon trigger primitives (muon track segments) was studied using 36 CMS CSCs and cosmic ray muons during the Magnet Test and Cosmic Challenge (MTCC) exercise conducted by the CMS experiment in 2006. In contrast to earlier studies that used muon beams to illuminate a very small chamber area (<0.01m2), results presented in this paper were obtained by many installed CSCs operating in situ over an area of ≈23m2 as a part of the CMS experiment. The efficiency of finding two-dimensional trigger primitives within six-layer chambers was found to be 99.93±0.03%. These segments, found by the CSC electronics within 800 ns after the passing of a muon through the chambers, are the input information for the Level-1 muon trigger and, also, are a necessary condition for chambers to be read out by the Data Acquisition System.

In this note, we propose an algorithm for fast and efficient track segment reconstruction in Cathode Strip Chambers used by the Compact Muon Solenoid 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 Cosmics Muon data and found to surpass the HLT requirements.

We present the results from a search for gravitational-wave transients associated with core-collapse supernovae observed optically within 30 Mpc during the third observing run of Advanced LIGO and Advanced Virgo. No gravitational wave associated with a core-collapse supernova has been identified. We then report the detection efficiency for a variety of possible gravitational-wave emissions. For neutrino-driven explosions, the distance at which we reach 50% detection efficiency is up to 8.9 kpc, while more energetic magnetorotationally-driven explosions are detectable at larger distances. The distance reaches for selected models of the black hole formation, and quantum chromodynamics phase transition are also provided. We then constrain the core-collapse supernova engine across a wide frequency range from 50 Hz to 2 kHz. The upper limits on gravitational-wave energy and luminosity emission are at low frequencies down to $10^{-4}\,M_\odot c^2$ and $5 \times 10^{-4}\,M_\odot c^2$/s, respectively. The upper limits on the proto-neutron star ellipticity are down to 5 at high frequencies. Finally, by combining the results obtained with the data from the first and second observing runs of LIGO and Virgo, we improve the constraints of the parameter spaces of the extreme emission models. Specifically, the proto-neutron star ellipticities for the long-lasting bar mode model are down to 1 for long emission (1 s) at high frequency.

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 report on the results of testing two six-layer 0.6 × 0.6 m2 cathode strip chamber (CSC) prototypes in a muon beam at CERN. The prototypes were designed to simulate sections of the end-cap muon system of the Compact Muon Solenoid (CMS) detector which will be installed at the Large Hadron Collider (LHC). We measured the spatial and time resolutions of each chamber for different gains, different orientations with respect to the beam direction and different strength magnetic fields. The single-layer spatial resolution of a prototype with a strip pitch of 15.88 mm ranged from 78 to 468 μm, depending on whether the particle passed between two cathode strips or through the center of a strip; its six-layer resolution was found to be 44 μm. The single-layer spatial resolution of a prototype with a strip pitch of 6.35 mm ranged from 54 to 66 μm; its six-layer resolution was found to be 23 μm. The efficiency for collecting an anode wire signal from one of six layers within a 20 ns time window appropriate for the LHC was found to be greater than 95% in normal running conditions.

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.

Presented are the main design features and performance results of the Cathode Strip Chambers for the CMS Endcap Muon system. Although the strips are unusually wide (up to 16mm) for the cathode-to-anode wire distance of 5mm, the six-plane structure of these chambers yields a spatial resolution of about 80μm, essentially uniform and independent of the strip width. In addition, the net spatial resolution of about one-tenth of the strip width at the hardware trigger level (300ns) is obtained using a simple network of comparators. Time resolution achieved at the trigger level is ∼4ns (rms) that allows unambiguous tagging of bunch crossings which occur every 25ns. Aging test results, including those obtained with a recirculating gas system, are discussed; only minor aging affects were observed. The aging studies were performed with large-scale chambers; 700m of wire were irradiated for a dose up to 0.4C/cm of the total accumulated charge.

Presented are the main design features of the large cathode strip chambers (CSCs) for the CMS endcap muon system as well as the performance results obtained with the first large-scale prototype. The 3.4×1.2 m2 six-plane prototype has been reliably operated over one year and the cosmic-ray tests showed that it was capable of detecting muons with ∼80 μm spatial and ∼5 ns time resolutions.

Stochastic gravitational waves (SGW) can be detected by measuring a cross-correlation of two or more gravitational wave (GW) detectors. In this paper we describe an optimal SGW search technique in the wavelet domain. It uses a sign correlation test, which allows calculation of the cross- correlation significance for non-Gaussian data. We also address the problem of correlated noise for the GW detectors. A method that allows calculation of the cross-correlation variance, when data is affected by correlated noise, is developed. As a part of the optimal search technique a robust estimator for detector noise spectral amplitude is introduced. It is not sensitive to outliers and allows application of the search technique to non-stationary data.

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.

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.

Most compact binary systems are expected to circularize before the frequency of emitted gravitational waves (GWs) enters the sensitivity band of the ground based interferometric detectors. However, several mechanisms have been proposed for the formation of binary systems, which retain eccentricity throughout their lifetimes. Since no matched-filtering algorithm has been developed to extract continuous GW signals from compact binaries on orbits with low to moderate values of eccentricity, and available algorithms to detect binaries on quasicircular orbits are suboptimal to recover these events, in this paper we propose a search method for detection of gravitational waves produced from the coalescences of eccentric binary black holes (eBBH). We study the search sensitivity and the false alarm rates on a segment of data from the second joint science run of LIGO and Virgo detectors, and discuss the implications of the eccentric binary search for the advanced GW detectors.

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.

Should an event excess compatible with the H → ZZ(∗) → 4μ decay channel be observed at LHC, the statistical significance of the access must be properly scaled down to account for the systematic errors and the fact that the search is performed in a wide-open range of possible Higgs boson masses. We present results of studies addressing both of the two contributions and show that the required corrections in Higgs boson search in this particular channel are by far not negligible.

A detailed study of the same-sign muon signature within the mSUGRA model was performed. Selection criteria based on the missing transverse energy in the events and the jet and muon transverse momenta are applied to select the data sample. An excess of SUSY events over the Standard Model background processes can be statistically significant for many benchmark points for an integrated luminosity of less than 10fb 1 . The analysis shows that m1=2 up to 650 GeV/c 2 can be reached at 5 level with 10fb 1 . Full detailed detector simulation, trigger emulation and reconstruction were performed.

ConclusionsLIGO promises to open a new window on here to fore unobservable astrophysical processes in the universe through its ability to detect directly gravitational waves. The detection of gravitational radiation, in itself a formidable scientific challenge, will also allow us to observe the dynamics of astrophysical events such as binary star coalescences and supernovae explosions in new ways. The LIGO detectors will become operational in 2000.

A detailed study of the same-sign muon signature within the mSUGRA model is described. Selection criteria based on the missing transverse energy in the events and the jet and muon transverse momenta are applied. The results indicate that an excess of SUSY events over the Standard Model background processes can be statistically significant for an integrated luminosity of less than 10 fb^-1 for many benchmark points with m_1/2 up to 650 GeV/c^2.

Presented are the main design features and performance results of the cathode strip chambers (CSCs) for the CMS Endcap Muon System. The six-plane structure of these chambers yields a spatial resolution of about 80 /spl mu/m, essentially uniform and independent of the strip width (up to 16 mm, which is unusually wide for the cathode-to-anode wire distance of 5 mm). In addition, the net spatial resolution of about one-tenth of the strip width at the hardware trigger level (300ns) is obtained using a simple network of comparators. The time resolution achieved at the trigger level is /spl sim/4ns (RMS) that allows unambiguous tagging of bunch crossing occurring every 25 ns. Aging tests, including those obtained with a recirculating gas system, showed only minor aging effects. The aging studies were performed with large-scale chambers; 700 m of wire were irradiated for a dose up to 0.4 C/cm of the total accumulated charge.

By probing the population of binary black hole (BBH) mergers detected by LIGO-Virgo, we can infer properties about the underlying black hole formation channels. A mechanism known as pair-instability (PI) supernova is expected to prevent the formation of black holes from stellar collapse with mass greater than $\sim 40-65\,M_\odot$ and less than $\sim 120\,M_\odot$. Any BBH merger detected by LIGO-Virgo with a component black hole in this gap, known as the PI mass gap, likely originated from an alternative formation channel. Here, we firmly establish GW190521 as an outlier to the stellar-mass BBH population if the PI mass gap begins at or below $65\, M_{\odot}$. In addition, for a PI lower boundary of $40-50\, M_{\odot}$, we find it unlikely that the remaining distribution of detected BBH events, excluding GW190521, is consistent with the stellar-mass population.

The low-energy characteristics of the pion Compton effect can be determined from the radiative scattering of high-energy pions in a nuclear Coulomb field. Numerical calculations are carried out for pions with an initial momentum 40 GeV/c.