Michail Bachtis

A bstract The discovery by the ATLAS and CMS experiments of a new boson with mass around 125 GeV and with measured properties compatible with those of a Standard-Model Higgs boson, coupled with the absence of discoveries of phenomena beyond the Standard Model at the TeV scale, has triggered interest in ideas for future Higgs factories. A new circular e + e − collider hosted in a 80 to 100 km tunnel, TLEP, is among the most attractive solutions proposed so far. It has a clean experimental environment, produces high luminosity for top-quark, Higgs boson, W and Z studies, accommodates multiple detectors, and can reach energies up to the $$ \mathrm{t}\overline{\mathrm{t}} $$ threshold and beyond. It will enable measurements of the Higgs boson properties and of Electroweak Symmetry-Breaking (EWSB) parameters with unequalled precision, offering exploration of physics beyond the Standard Model in the multi-TeV range. Moreover, being the natural precursor of the VHE-LHC, a 100 TeV hadron machine in the same tunnel, it builds up a long-term vision for particle physics. Altogether, the combination of TLEP and the VHE-LHC offers, for a great cost effectiveness, the best precision and the best search reach of all options presently on the market. This paper presents a first appraisal of the salient features of the TLEP physics potential, to serve as a baseline for a more extensive design study.

In this study, we apply the geometrical properties of the Legendre transform in order to implement a segment reconstruction algorithm for drift tube chambers used in High Energy Physics experiments. The output signal of a drift tube chamber consists of a collection of circles, each of which corresponds to a drift tube and defines the trajectory of the charged particle. The particle track candidate is reconstructed as the common tangent line to the drift circles. We tested the method both on an ideal case and on a case of high noise conditions using Monte Carlo generated tracks.

The Compact Muon Solenoid (CMS) Trigger of the Large Hadron Collider (LHC) particle accelerator at CERN selects potentially interesting particle collision data to process and archive for further study. The first stage of the trigger system, the hardware-based L1 Trigger, must sift through roughly 3 terabits/second of data describing the energy distribution of particles generated in the collisions, and reduce it to 100 megabits/second of event data that subsequent systems can handle. Without the CMS Trigger, the amount of experiment-generated data would quickly outstrip the archiving ability of the LHC system. Because of the sheer amount of input data and the rate at which it is generated, the hardware-based L1 Trigger is subject to stringent performance requirements. These will become even more severe as the LHC is upgraded over the next ten years, requiring a careful redesign of the L1 Trigger hardware. For example, future upgrades may introduce particle motion-tracking data into the L1 Trigger, resulting in an increased input data rate of up to 40 terabits/second. The need to modify the design as the LHC system is upgraded, the low-volume cost advantages of FPGAs, and a desire for a flexible and adaptable system all point toward the use of FPGAs as a hardware implementation solution. In this paper, we present several different FPGA implementations of the electron/photon identification module, a key part of the new Clustering Algorithm for the upgraded L1 Trigger. We analyze the resource requirements and performance tradeoffs, and present a qualitative discussion of flexibility to meet the changing needs of the CMS experiment. Finally, we narrow potential design choices to the top candidates and use one in a full Clustering Algorithm implementation.

We present a design for the Phase-1 upgrade of the Compact Muon Solenoid (CMS) calorimeter trigger system composed of FPGAs and Multi-GBit/sec links that adhere to the μTCA crate Telecom standard. The upgrade calorimeter trigger will implement algorithms that create collections of isolated and non-isolated electromagnetic objects, isolated and non-isolated tau objects and jet objects. The algorithms are organized in several steps with progressive data reduction. These include a particle cluster finder that reconstructs overlapping clusters of 2x2 calorimeter towers and applies electron identification, a cluster overlap filter, particle isolation determination, jet reconstruction, particle separation and sorting.

The CMS Regional Calorimeter Trigger (RCT) receives eight-bit energies and a data quality bit from the HCAL and ECAL Trigger Primitive Generators (TPGs). The RCT uses these trigger primitives to find e/γ candidates and calculate regional calorimeter sums that are sent to the Global Calorimeter Trigger (GCT) for sorting and further processing. The RCT hardware consists of one clock distribution crate and 18 double-sided crates containing custom boards, ASICs, and backplanes. The RCT electronics have been completely installed since 2007. The RCT has been integrated into the CMS Level-1 Trigger chain. Regular runs, triggering on cosmic rays, prepare the CMS detector for the restart of the LHC. During this running, the RCT control is handled centrally by CMS Run Control and Monitor System communicating with the Trigger Supervisor. Online Data Quality Monitoring (DQM) evaluates the performance of the RCT during these runs. Offline DQM allows more detailed studies, including trigger efficiencies. These and other results from cosmicray data taking with the RCT will be presented.

The Standard Model is a very successful theory in predicting the experimental observations through the latest years. With a possible discovery of the Higgs boson, the SM will be a theory of almost everything. However questions arise when the Standard Model is seen as part of a larger unified theory.

As the LHC increases luminosity and energy, it will become increasingly difficult to select interesting physics events and remain within the readout bandwidth limitations. An upgrade to the CMS Calorimeter Trigger implementing more complex algorithms is proposed. It utilizes AMC cards with Xilinx FPGAs running in microTCA crate with card interconnections via crate backplanes and optical links operating at up to 10 Gbps. Prototype cards with Virtex-6 and Virtex-7 FPGAs have been built and software frameworks for operation and monitoring developed. The physics goals, hardware architectures, and software will be described in this talk. More details can be found in a separate poster at this conference.

In this study, the geometrical properties of the Legendre transform are used to implement a segment reconstruction algorithm for drift tube chambers used in high energy physics experiments. The output signal of a drift tube chamber consists of co-centric circles in each drift tube that define the possible points of the charged particle trajectory. The particle track is reconstructed as the common tangent line to the drift circles. The method is tested on an ideal case and on a case of high noisy conditions using Monte Carlo generated tracks.

The work presented in this thesis spans a wide range of experimental particle physics subjects, starting from level-1 trigger electronics to the final results of the search for Higgs boson decay and t

The discovery by the ATLAS and CMS experiments of a new boson with mass around 125 GeV and with measured properties compatible with those of a Standard-Model Higgs boson, coupled with the absence of discoveries of phenomena beyond the Standard Model up to scales of several hundred GeV, has triggered interest in ideas for future Higgs factories.A new circular e + e - collider hosted in a 80 to 100 km tunnel, TLEP, is among the most attractive solutions proposed so far.It has a clean experimental environment, produces high luminosity for Higgs boson studies, accommodates multiple detectors, and can reach energies up to the t t threshold and beyond.Moreover, being the natural precursor of the VHE-LHC, a 100 TeV hadron machine in the same tunnel, it builds up a long-term vision for particle physics.This paper describes the expected precision on the measurement of the Higgs boson couplings with a TLEP run between 250 and 350 GeV.

Based on the phenomenological results of spontaneous symmetry breaking in the SM and the MSSM

Pursuit of answers to fundamental questions of life and nature is time invariant. The atomic hypothesis of matter was first brought up by Democritus in 400 B.C. Democritus stated that everything consists of atoms which are physically but not geometrically indivisible.

The first step of the analysis is the selection of high quality di-tau candidates that can be used for Z cross section measurement and Higgs searches

Taus, being the heaviest of the leptons, constitute an important tool for searches for new physics at the LHC. Higgs boson couples to mass leading to a significant branching ratio of about 10% for low mass Higgs decaying to tau pairs. Taus become even more important in the minimal supersymmetric extension of the Standard model where the neutral Higgs production is enhanced and the presence of two Higgs doublets results in prediction of additional charged Higgs bosons that may preferentially decay to final states with tau leptons. This paper describes a search for Higgs bosons decaying to di-tau pairs and a search for charged Higgs bosons decaying to taus and neutrinos using about 1 fb−1 of data collected with the CMS detector in 2011.

High performance hadronic tau identification is crucial for measurements and searches of new physics in final states involving tau leptons.

Studies of Z bosons decaying to taus constitute a test of the Standard Model in the new energy regime as well as a benchmark process for Higgs searches.This paper describes the first results of Z to tau tau studies performed with 1.7 pb -1 of data collected with CMS detector up to end of Summer 2010.

The collected collision information from all sub-detectors is stored in ‘raw’ data format that can be used for online event reconstruction (in HLT) or offline event reconstruction for data analysis.

Physics and detector simulation is necessary in high energy physics to model complex physics processes, optimize analysis techniques and understand the performance of the numerous and complex sub-detectors of an apparatus such as CMS.

The Large Hadron Collider (LHC) is a superconducting hadron accelerator and collider consisting of two rings that are installed in the existing 26.7 km tunnel that was constructed between 1984 and 1989 for the LEP machine [1].

In the previous chapters, a complete study of the di-tau final state at $$\sqrt{s}\,=\,7\,{\,\mathrm{TeV}}$$ was presented using the complete dataset collected by the CMS Detector during the 2011 LHC run.

This chapter presents a measurement of the $$Z$$ production cross section when $$Z$$ decays to tau pairs using the 2011 data sample.

New Physics beyond the Standard Model could well preferentially show up at the LHC in final states with taus.The development of efficient and accurate reconstrution and identification of taus is therefore an important item in the CMS physics programme.The potentially superior performance of a particle-flow approach can help to achieve this goal with the CMS detector.Preliminary strategies are presented in this summary for the hadronic decays of the taus.

In this note the Detector Control System (DCS) for the power supply (PS) of the Monitored Drift Tube (MDT) chambers of the ATLAS experiment is presented. The principal task of DCS is to enable and ensure the coherent and safe operation of the detector. The interaction of the detector experts users or shifters with the detector hardware is also performed via DCS. This system monitors the operational parameters and the overall state of the detector, the alarm generation and handling, the connection of hardware values to databases and the interaction with the Data Acquisition system (DAQ). In this note the Power System (PS) system as a Detector Control Subsystem is presented. Furthermore, it is outlined in detail what is the front-end to be controlled and how the architecture of the back-end is established. I. DETECTOR CONTROL SYSTEM IN ATLAS EXPERIMENT The work performed for the LEP experiments concerning the DCS, provided us with a useful and important experience and knowledge. On the other hand the implementation and integration of DCS in the LHC era, seems to be much different [1]. The basic change has to do with the introduction of new tools. The ATLAS Detector follows all the basic DCS guidelines of the LHC experiments, but in parallel, creates its own framework that facilitates the development and ensures further the homogeneity among the various ATLAS detector control subsystems. A. Tools For Detector Control System In the late 90-s, the four LHC experiments decided to set up the Joint Controls Project [2]. After a detailed investigation a decision was made to use the commercial PVSS-II [3] as the Supervisor Control and Acquisition System (SCADA) tool to construct the back-end control systems. The very next step was the integration of a software framework based on the chosen package, in order to integrate, sequence and automate the control process of the LHC experiments. B. PVSS-II The PVSS SCADA system provides the following main components and tools: 1. A run time database. 2. Alarm generation and handling. 3. Graphical Editor. 4. Graphical Parameterization tool connected to the structure of the database. 5. Scripting language following C syntax. 6. Drivers for the connection between the PVSS and hardware. C. JCOP and ATLAS framework Given the increasing constraints on manpower, as well as the evident similarity in technical requirements for controls amongst the experiments, the project should enable more efficient use of resources to be made. The JCOP framework is an integrated set of guidelines and software tools which is used by DCS developers during the implementation of their own control system application. The framework includes as far as possible all templates, standard elements and functions required to achieve an homogenous control system. The framework provides guidelines for • Integration and development • Organization of libraries, panels, scripts • Naming convention (PVSS system, library and panel names) • Look and feel conventions (panel size, trend display, colors) • Programming (control script) Besides the main functionalities given above, the JCOP framework supports its users with even more specific tools. Such tools can be used for DAQ (Data Acquisition) connection, access control or connection with databases. But the most important offer of this framework that should be underlined, is that this is the main component for the organization and automation of the DCS of the back-end system. Finally, it should be mentioned that except of the JCOP framework described above, the central DCS team of ATLAS experiment has established a special ATLAS DCS framework [4]. This framework provides the DCS developers with extra conventions, libraries and software tools and keeps the hole ATLAS DCS project as coherent as possible. II. MONITORED DRIFT TUBE (MDT) CHAMBERS AND THE POWER SUPPLY A. The MDT chambers and the geometrical representation The Monitored Drift Chambers (MDT) are the high precision tracking chambers of the ATLAS muon spectrometer. They are designed to operate reliably in a high rate and high background environment and to provide a good spatial resolution [5]. Each MDT consists of layers of drift tubes filled with a gas mixture of Ar:CO2 (93% : 7%). Each drift tube is constructed with a grounded metallic cathode cylinder and an anode wire, passing through its center, held at a positive potential. A charged particle passing through the tube ionizes the gas along its path. The resulting electron avalanche travels towards the wire, while the produced ions drift towards the cathode cylinder, generating a trigger pulse that is detected by the detector electronics. The ATLAS Muon Spectrometer is composed of 1168 MDT chambers which is divided in two main regions, Barrel region, including 656 chambers, and the Endcap region, including 512 chambers, and two sides, side A and C with respect to the interaction point. The Barrel region (pseudorapidity η < 1.2) is formed of three concentric to the beam axis cylinders. They are positioned at a radii of about 5, 7 and 10 m. These cylinders are called layers and thus there is the Barrel Inner (BI) layer, the Barrel Middle (BM) layer and the Barrel Outer (BO) layer. Finally another useful geometric entity is the sector. The Muon Spectrometer is subdivided into 16 sectors around the φ coordinate[5]. In the endcap region (pseudorapidity 1.2 < η < 2.0 ) every side is arranged in four vertical to the beam line disks at distances of about 7, 10, 14 and 21 meters from the interaction point. These disks are called again layers and thus there is the Endcap Inner (EI) layer, Endcap EE (EE) layer for EE chambers, Endcap Middle (EM) layer and Endcap Outer (EO) layer. Endcap region like barrel is subdivided in 16 sectors [5]. B. Power Supply Hardware The operating voltage for an MDT chamber is 3080 Volts. When LHC will reach full luminosity the maximum (depending on size and position) current requirement is about 0,7 mA [5]. One High Voltage channel supplies one chamber multilayer; each MDT chamber is divided into 2 multilayers. The Low Voltage required for the chamber electronics is 5 Volts. The signals coming from tubes are collected by the mezzanine boards [5]. Each mezzanine board processes signals coming from 24 tubes and requires 5V as an input voltage. The data coming from mezzanine boards are multiplexed in a digital board called CSM (Chamber Service Module). The CSM sends the data to be read out by the DAQ and needs 5V and about 1 A of current to operate too. One low voltage channel supplies in parallel two MDT chambers. SY1527 System Mainframe ... B ra nc hC on tro lle r B ra nc hC on tro lle r B ra nc hC on tro lle r

Abstract The upgraded L1 muon trigger system of the CMS experiment in the High Luminosity Large Hadron Collider is based on custom processors featuring large Field Programmable Gate Arrays (FPGAs) connected by large numbers of optical links. These provide the I/O bandwidth and power necessary to process the complex algorithms used during the collection of physics data. The design and performance requirements of these processors creates significant challenges in signal integrity, power delivery, and thermal management. In this paper we describe the Octopus processor, featuring a large Xilinx Virtex Ultrascale+ FPGA and up to 128 links interfaced to optics through high quality twin-ax copper cables. Results on signal integrity at 25 Gb/s and the first demonstration of 50+ Gb/s links with pluggable optics in CMS are also shown, demonstrating bit error rates below 10 −15 at a 95% confidence level. The thermal performance is measured inside an Advanced-TCA crate with acceptable thermal margins up to 200 W of chip power. Future improvements are mentioned, potentially allowing operation at up to 300 W.

The Barrel Muon Track finder of the CMS experiment at the Large Hadron Collider uses custom processors to identify muons and measure their momenta in the central region of the CMS detector. An upgrade of the L1 tracking algorithm is presented, featuring a Kalman Filter in FPGAs, implemented using High Level Synthesis tools. The matrix operations are mapped to the DSP cores reducing resource utilization to a level that allows the new algorithm to fit in the same FPGA as the legacy one, thus enabling studies during nominal CMS data taking. The algorithm performance has been verified in CMS collisions during 2018 operations. The algorithm is also proposed for standalone muon tracking at the High Luminosity LHC. The algorithm development is complemented by ATCA processor R&D featuring a large ZYNQ Ultrascale+ SoC with high speed optical links.