Large Hadron Collider Upgrade Research Articles

A data acquisition system for HV-CMOS sensor research and development in the upgrade of ATLAS experiment.

In the high luminosity Large Hadron Collider upgrade of the A Toroidal LHC ApparatuS (ATLAS) experiment in 2026, the new inner tracker detector will be installed. As a promising candidate for the outer layer of the inner tracker detector, the High Voltage CMOS (HV-CMOS) pixel sensors are being investigated by the ATLAS collaboration. A Front-End LInk eXchange (FELIX) based Data Acquisition (DAQ) system is developed for the R&D of the HV-CMOS sensors. A FELIX card with a Peripheral Component Interconnect express interface in the back-end is used to control, monitor, calibrate, and read out the front-end electronics. In the front-end, a Xilinx evaluation board ZC706 works as the interface between the back-end and the custom boards with HV-CMOS sensors and the readout Application-Specific Integrated Circuit. The DAQ system was successfully deployed for the testbeam experiment at CERN. The design of the DAQ system, the tuning of sensors, and the testbeam results will be described in details.

The LHeC Project: e-Ring Revisited

Construction of a new 9 km long e-ring tangential to the Large Hadron Collider (LHC) has been proposed as an option for QCD-Explorer stage of the Large Hadron electron Collider (LHeC). It is shown that L=1033 cm-2 s -1 can be achieved with 90 MW synchrotron radiation losses. This luminosity value, which coincides with basic version of ERL60LHC, will be sufficient for precise determination of (Parton Distribution Function) PDFs for LHC, as well as exploration of QCD basics, especially small x Björken region up to 10-6 at Q2 ≈ 1 GeV2 . In addition, some comments on basic and upgraded versions of ERL60LHC are presented as well. It is shown that upgraded ERL60LHC version with L=1034 cm-2 s -1 requires high wall plug power exceeding 160 MW.

Induced activation studies for the LHC upgrade to High Luminosity LHC

The Large Hadron Collider (LHC) will be upgraded in 2019/2020 to increase its luminosity (rate of collisions) by a factor of five beyond its design value and the integrated luminosity by a factor ten, in order to maintain scientific progress and exploit its full capacity. The novel machine configuration, called High Luminosity LHC (HL-LHC), will increase consequently the level of activation of its components. The evaluation of the radiological impact of the HL-LHC operation in the Long Straight Sections of the Insertion Region 1 (ATLAS) and Insertion Region 5 (CMS) is presented. Using the Monte Carlo code FLUKA, ambient dose equivalent rate estimations have been performed on the basis of two announced operating scenarios and using the latest available machine layout. The HL-LHC project requires new technical infrastructure with caverns and 300 m long tunnels along the Insertion Regions 1 and 5. The new underground service galleries will be accessible during the operation of the accelerator machine. The radiological risk assessment for the Civil Engineering work foreseen to start excavating the new galleries in the next LHC Long Shutdown and the radiological impact of the machine operation will be discussed.

Mechanical Design Analysis of MQXFB, the 7.2-m-Long Low- $\beta$ Quadrupole for the High-Luminosity LHC Upgrade

As part of the High-Luminosity Large Hadron Collider (LHC) Project, a set of Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn quadrupoles are being developed, aiming to enhance the performance of the inner triplets. The new magnets, identified as MQXFA and MQXFB, will share the same cross section with two different lengths, 4.2 and 7.2 m, respectively. During the magnet development, three short models were tested, along with a number of mechanical models, demonstrating the capability of the magnet cross section to achieve the specified performances. The same performances are now required for the full-length magnets. To ensure this, the authors studied the impact of the magnet length on the capability of the structure to provide an adequate support to the coils. Finite element and simplified analytical models were used to evaluate the impact of the magnet length on the stresses in the magnet ends and coil elongation during powering. The models were calibrated using the results from the short model tests, and used to provide an indication on the required prestress and its foreseen impact on the magnet performance.

Field Measurement to Evaluate Iron Saturation and Coil End Effects in a Modified Model Magnet of Beam Separation Dipole for the HL-LHC Upgrade

A beam separation dipole magnet for the high luminosity large hadron collider upgrade is developed. The development of the 2-m-long model magnet (MBXFS1) was initiated so as to evaluate the design and performance of the beam separation dipole magnet. In the first cold test in 2016, the quench performance was not satisfactory because the coil prestress at the pole was completely released during excitation. After reassembly to improve the quench performance, the excitation test of the modified model magnet (MBXFS1b) was performed at 1.9 K in 2017 at KEK. Due to the large coil aperture and limited outer diameter of the iron yoke, the control of iron saturation effects on the field quality has been a design issue. Regarding the magnetic performance, field saturation effects on the transfer function and the multipole field variation along the excitation, and coil end effects to the straight section need to be evaluated by the field measurement. In this paper, field measurement results will be presented and the comparison with the three-dimensional field calculation will be discussed.

Modeling of beam-induced damage of the LHC tertiary collimators

Modern hadron machines with high beam intensity may suffer from material damage in the case of large beam losses and even beam-intercepting devices, such as collimators, can be harmed. A systematic method to evaluate thresholds of damage owing to the impact of high energy particles is therefore crucial for safe operation and for predicting possible limitations in the overall machine performance. For this, a three-step simulation approach is presented, based on tracking simulations followed by calculations of energy deposited in the impacted material and hydrodynamic simulations to predict the thermomechanical effect of the impact. This approach is applied to metallic collimators at the CERN Large Hadron Collider (LHC), which in standard operation intercept halo protons, but risk to be damaged in the case of extraction kicker malfunction. In particular, tertiary collimators protect the aperture bottlenecks, their settings constrain the reach in ${\ensuremath{\beta}}^{*}$ and hence the achievable luminosity at the LHC experiments. Our calculated damage levels provide a very important input on how close to the beam these collimators can be operated without risk of damage. The results of this approach have been used already to push further the performance of the present machine. The risk of damage is even higher in the upgraded high-luminosity LHC with higher beam intensity, for which we quantify existing margins before equipment damage for the proposed baseline settings.

Progress on the Development of the Nb3Sn 11T Dipole for the High Luminosity Upgrade of LHC

The high-luminosity large hadron collider (LHC) project at CERN entered into the production phase in October 2015 after the completion of the design study phase. In the meantime, the development of the 11 T dipole needed for the upgrade of the collimation system of the machine made significant progress with very good performance of the first two-in-one magnet model of 2-m length made at CERN. The 11 T dipole, which is more powerful than the current main dipoles of LHC, can be made shorter with an equivalent integrated field. This will allow creating space for the installation of additional collimators in specific locations of the dispersion suppressor regions. Following tests carried out during heavy ions runs of LHC in the end of 2015, and a more recent review of the project budget, the installation plan for the 11 T dipole was revised. Consequently, one 11 T dipole full assembly containing two 11 T dipoles of 5.5-m length will be installed on either side of interaction point 7. These two units shall be installed during the long shutdown 2 in years 2019-2020. After a brief reminder on the design features of the magnet, this paper describes the current status of the development activities, in particular the short model programme and the construction of the first full scale prototype at CERN. Critical operations such as the reaction treatment and the coil impregnation are discussed, the quench performance tests results of the two-in-one model are reviewed and finally, the plan toward the production for the long shut down 2 is described.

Magnetic Field Measurement of 2-m-Long Model of Beam Separation Dipole for the HL-LHC Upgrade

KEK has been developing a beam separation dipole magnet for the high luminosity large hadron collider upgrade. The magnet has a coil aperture of 150 mm and uses NbTi superconducting cable. A dipole magnetic field of 5.6 T is generated at 12 kA at 1.9 K to provide a field integral of 35 T·m. KEK has started the development of the first 2-m-long model magnet to evaluate the design and performance of the beam separation dipole magnet. The excitation test at 1.9 K of the first 2-m-long model magnet was performed from April to June 2016 at KEK. This paper presents the results of the magnetic field measurements of the first 2-m-long model magnet by a rotating coil probe.

New Analysis Framework Software for the CERN Superconducting Magnet Test Facility

Since 2013, the existing but aging analysis tools that were routinely used for the large hadron collider (LHC) magnet series production measurement campaigns conducted at the CERN superconducting Magnet Test Facility (SM18) are being replaced by a novel open-data and user-driven analysis environment. This effort is running in parallel to the current development of magnet prototypes in the framework of the High Luminosity Upgrade of the CERN LHC (HL-LHC project). This R&D phase requires new features in the quench analysis software to cope with the dedicated or specific magnet tests (splice resistance, inductance, ac loss, Quench Heater efficiency, Hot Spot Temperature assessment, etc…), as well as a more open access to the mathematical routines and to the output results. The new data handling and analysis tools framework that is currently deployed is based on two pillars. First, the availability of the legacy proprietary raw data in an open and widely accessible format. Second, the new possibility for the user to process with the data through dedicated numerical tools and algorithms recently developed for data viewing, analysis, and formatted test result reports. In this paper, the initial analysis framework is described in terms of the acquisition system that produces data, the conversion tool that standardizes the file format, the new analysis tool that replaces the existing quench analysis software, and the database tool that archives the summary of every test. Finally, some statistics of the current situation are presented, based on facts and results of one year of analysis working within the superconducting magnet test facility.

Performance of radiation-hard HV/HR CMOS sensors for the ATLAS inner detector upgrades

A major upgrade (Phase II Upgrade) to the Large Hadron Collider (LHC), scheduled for 2022, will be brought to the machine so as to extend its discovery potential. The upgraded LHC, called High-Luminosity LHC (HL-LHC), will run with a nominal leveled instantaneous luminosity of 5×1034 cm−2s−1, more than twice the expected luminosity. This unprecedented luminosity will result in higher occupancy and background radiations, which will request the design of a new Inner Tracker (ITk) which should have higher granularity, reduced material budget and improved radiation tolerance. A new pixel sensor concept based on High Voltage and High Resistivity CMOS (HV/HR CMOS) technology targeting the ATLAS inner detector upgrade is under exploration. With respect to the traditional hybrid pixel detector, the HV/HR CMOS sensor can potentially offer lower material budget, reduced pixel pitch and lower cost. Several prototypes have been designed and characterized within the ATLAS upgrade R&D effort, to investigate the detection and radiation hardness performance of various commercial technologies. An overview of the HV/HR CMOS sensor operation principle is described in this paper. The characterizations of three prototypes with X-ray, proton and neutron irradiation are also given.

Level-1 pixel based tracking trigger algorithm for LHC upgrade

The Pixel Detector is the innermost detector of the tracking system of the Compact Muon Solenoid (CMS) experiment at CERN Large Hadron Collider (LHC) . It precisely determines the interaction point (primary vertex) of the events and the possible secondary vertexes due to heavy flavours (b and c quarks); it is part of the overall tracking system that allows reconstructing the tracks of the charged particles in the events and combined with the magnetic field to measure their momentum. The pixel detector allows measuring the tracks in the region closest to the interaction point. The Level-1 (real-time) pixel based tracking trigger is a novel trigger system that is currently being studied for the LHC upgrade. An important goal is developing real-time track reconstruction algorithms able to cope with very high rates and high flux of data in a very harsh environment. The pixel detector has an especially crucial role in precisely identifying the primary vertex of the rare physics events from the large pile-up (PU) of events. The goal of adding the pixel information already at the real-time level of the selection is to help reducing the total level-1 trigger rate while keeping an high selection capability. This is quite an innovative and challenging objective for the experiments upgrade for the High Luminosity LHC (HL-LHC) . The special case here addressed is the CMS experiment. This document describes exercises focusing on the development of a fast pixel track reconstruction where the pixel track matches with a Level-1 electron object using a ROOT-based simulation framework.

The data acquisition system for a fixed target experiment at NICA complex at JINR and its connection to the ATLAS TileCal readout electronics

Today's large-scale science projects have always encountered challenges in processing large data flow from the experiments, the ATLAS detector records proton-proton collisions provided by the Large Hadron Collider (LHC) at CERN every 50 ns which results in a total data flow of 10 Pb/s. These data must be reduced to the science data product for further analysis, thus a very fast decisions need to be executed, to modify this large amounts of data at high rates. The capabilities required to support this scale of data movement is development and improvement of high-throughput electronics. The upgraded LHC will provide collisions at rates that will be at least 10 times higher than those of today due to it's luminosity by 2022. This will require a complete redesign of the read-out electronics and Processing Units (PU) in the Tile-calorimeter (TileCal) of the ATLAS experiment. A general purpose, high-throughput PU has been developed for the TileCal at CERN, by using several ARM-processors in cluster configuration. The PU is capable of handling large data throughput and apply advanced operations at high rates. This system has been proposed for the fixed target experiment at NICA complex to handle the first level processes and event building. The aim of this work is to have a look at the architecture of the data acquisition system (DAQ) of the fixed target experiment at the NICA complex at JINR, by compiling the data-flow requirements of all the subcomponents. Furthermore, the VME DAQ modules characteristics to control, triggering and data acquisition will be described in order to define the DAQ with maximum readout efficiency, no dead time and data selection and compression.

Strategies for probing nonminimal dark sectors at colliders: The interplay between cuts and kinematic distributions

In this paper, we examine the strategies and prospects for distinguishing between traditional dark-matter models and models with non-minimal dark sectors --- including models of Dynamical Dark Matter (DDM) --- at hadron colliders. For concreteness, we focus on events with two hadronic jets and large missing transverse energy at the Large Hadron Collider (LHC). As we discuss, simple "bump-hunting" searches are not sufficient; probing non-minimal dark sectors typically requires an analysis of the actual shapes of the distributions of relevant kinematic variables. We therefore begin by identifying those kinematic variables whose distributions are particularly suited to this task. However, as we demonstrate, this then leads to a number of additional subtleties, since cuts imposed on the data for the purpose of background reduction can at the same time have the unintended consequence of distorting these distributions in unexpected ways, thereby obscuring signals of new physics. We therefore proceed to study the correlations between several of the most popular relevant kinematic variables currently on the market, and investigate how imposing cuts on one or more of these variables can impact the distributions of others. Finally, we combine our results in order to assess the prospects for distinguishing non-minimal dark sectors in this channel at the upgraded LHC.

8-Gbps-per-channel radiation-tolerant VCSEL drivers for the LHC detector upgrade

We present ASIC designs of VCSEL drivers for a single VCSEL (LOCld1), two individual VCSELs (LOCld2) and a four-channel VCSEL array (LOCld4). This work is for new detector readout systems needed in the Large Hadron Collider upgrade program. All ASICs are fabricated in a commercial 0.25-μ m Silicon-on-Sapphire CMOS technology. LOCld1 and LOCld2 have passed the 8-Gbps and 10-Gbps eye mask tests. Operating at 8 Gbps data rate, the measured total jitter of LOCld1 and LOCld2 is less than 30 ps, and the power comsuption is about 200 mW per channel with 6-mA bias current and 6.4-mA modulation current. The radiation tolerance of LOCld1 has been qualified with x-ray and high-energy neutron beam test.

Particle spectroscopy of supersymmetric SU(5) in light of the 125 GeV Higgs boson and muong−2data

The discovery of the Higgs boson at the Large Hadron Collider (LHC) has a great impact on the minimal supersymmetric extension of the Standard Model (MSSM). In the context of the constrained MSSM (CMSSM) and its extension with non-universal masses for the MSSM Higgs doublets (NUHM2), sparticles with masses $ > 1$ TeV are necessary to reproduce the observed Higgs boson mass of 125-126 GeV. On the other hand, there appears to be a significant amount of discrepancy between the measured muon $g-2$ and the Standard Model prediction. A successful explanation of this discrepancy in the MSSM requires new contributions involving relatively light sparticles with masses $ < 1$ TeV. In this paper, we attempt to accommodate the two conflicting requirements in an SU(5) inspired extension of the CMSSM. We assign non-universal but flavor blind soft supersymmetry breaking masses to the scalar components in $\bar 5$ and 10 matter supermultiplets. The two MSSM Higgs doublets in the 5, $\bar5$ representations of SU(5) are also assigned unequal soft mass$^2$ at $M_{GUT}$. We identify parameter regions which can simultaneously accommodate the observed Higgs boson mass and the muon $g-2$ data, and which are compatible with other phenomenological constraints such as neutralino dark matter relic abundance and rare B-meson decays. Some regions of the allowed parameter space will be explored at the upgraded LHC and by dark matter direct detection experiments.

Design Optimization of the New D1 Dipole for HL-LHC Upgrade

The High-Luminosity Large Hadron Collider upgrade (LHC) project aims to increase the peak luminosity of the LHC to 5 ×1034 cm - 2s - 1, and a total integrated luminosity of 3000 fb - 1 from 2020 to 2030 by upgrading the low-beta insertion system for the ATLAS and CMS experiments. The aperture of the insertion magnets including the focusing/defocusing quadrupoles and separation dipoles will be doubled to achieve a smaller β*. This paper presents the latest design updates of the separation dipole D1 magnet, including the study of the different cable types to vary the main field; the modifications of the iron shape for the new design options to minimize the iron saturation effect on field quality; and the optimization of the coil ends to reduce the peak field and higher order harmonic field integrals in the ends.

Characterization of Mechanical Properties of MgB2 conductor for Superconducting Link Project at CERN

In the framework of high luminosity upgrade of Large Hadron Collider at CERN, superconducting links are being developed. MgB2 wire is a candidate conductor for use in high- current cables. Mechanical properties of this material are of key importance for the definition of the cable design and operating conditions. In this study, we evaluated the Young’s modulus of MgB2 filaments extracted from ex situ processed composite wires. The wires were produced in unit lengths of about 1 km and used in high-current cables. Single fiber tensile test was carried out on fil- aments composed of MgB2, Nb barrier, and Nb–Ni reaction layer. From the unloading modulus of filament specimens measured with different gauge lengths, the Young’s modulus of composite filaments extracted from two different strands was determined to be 114 and 122 GPa at room temperature, respectively. By using the rule-of-mixture, the Young’s modulus of MgB2 was estimated to be lower than that reported for highly dense MgB2 bulks. The reason for such difference is discussed from the viewpoint of void fraction.

Progress in &lt;formula formulatype="inline"&gt;&lt;tex Notation="TeX"&gt;$\hbox{Nb}_{3}\hbox{Sn}$&lt;/tex&gt;&lt;/formula&gt; RRP Strand Studies and Rutherford Cable Development at FNAL

A strong push to Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn conductor development in the U.S. as well as in Europe has been driven by the development of Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn dipoles and quadrupoles for the Large Hadron Collider (LHC) luminosity upgrades. Rutherford cables with high aspect ratio are used for these magnets to achieve large fields and gradients at relatively low currents. At Fermilab National Accelerator Laboratory (FNAL), 40-strand keystoned cables with and without a stainless steel core were developed and produced using 0.7-mm Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn strands made by Oxford Superconducting Technology with 127 and 169 restacks using the Restacked Rod Process with either NbTa alloy or Ti doping. The performance and properties of such strands and cables were studied to evaluate possible candidates for the production magnets of the LHC upgrades. The electrical performance was first compared for wires under flat-rolling deformation and then in cables made with different processes and geometries. The round wires are also compared under tensile and compressive strain using a Walters' spring variable-temperature probe that was recently commissioned at FNAL. Finally, cable test results obtained with a 14 T/16 T Rutherford cable test facility with a bifilar sample and a superconducting transformer are shown.

Performance of drift-tube detectors at high counting rates for high-luminosity LHC upgrades

The performance of pressurized drift-tube detectors at very high background rates has been studied at the Gamma Irradiation Facility (GIF) at CERN and in an intense 20MeV proton beam at the Munich Van-der-Graaf tandem accelerator for applications in large-area precision muon tracking at high-luminosity upgrades of the Large Hadron Collider (LHC). The ATLAS muon drift-tube (MDT) chambers with 30mm tube diameter have been designed to cope with γ and neutron background hit rates of up to 500Hz/cm2. Background rates of up to 14kHz/cm2 are expected at LHC upgrades. The test results with standard MDT readout electronics show that the reduction of the drift-tube diameter to 15mm, while leaving the operating parameters unchanged, vastly increases the rate capability well beyond the requirements. The development of new small-diameter muon drift-tube (sMDT) chambers for LHC upgrades is completed. Further improvements of tracking efficiency and spatial resolution at high counting rates will be achieved with upgraded readout electronics employing improved signal shaping for high counting rates.

Development of a cryogenic load frame for the neutron diffractometer at Takumi in Japan Proton Accelerator Research Complex

To prepare for projects such as the Large Hadron Collider upgrade, International Thermonuclear Experimental Reactor and Demonstration reactor, it is important to form a clear understanding of stress-strain properties of the materials that make up superconducting magnets. Thus, we have been studying the mechanical properties of superconducting wires using neutron diffraction measurements. To simulate operational conditions such as temperature, stress, and strain, we developed a cryogenic load frame for stress-strain measurements of materials using a neutron diffractometer at Japan Proton Accelerator Research Complex (J-PARC) Takumi beam line. The maximum load that can be applied to a sample using an external driving machine is 50 kN. Using a Gifford-MacMahon cryocooler, samples can be measured down to temperatures below 10 K when loaded. In the present paper, we describe the details of the cryogenic load frame with its test results by using type-304 stainless steel wire.