BDAQ53, a versatile pixel detector readout and test system for the ATLAS and CMS HL-LHC upgrades

BDAQ53 is a readout system and verification framework for hybrid pixel detector readout chips of the RD53 family. These chips are designed for the upgrade of the inner tracking detectors of the ATLAS and CMS experiments. BDAQ53 is used in applications where versatility and rapid customization are required, such as in laboratory testing environments, test beam campaigns, and permanent setups for quality control measurements. It consists of custom and commercial hardware, a Python-based software framework, and FPGA firmware. BDAQ53 is developed as open source software with both software and firmware being hosted in a public repository.Comment: 6 pages, 6 figure

Development and evaluation of prototypes for the ATLAS ITk pixel detector

The ATLAS inner detector will be replaced by an all-silicon detector for the HL-LHC upgrade around 2025. The innermost five layers of the detector system will be pixel detector layers which will be most challenging in terms of radiation hardness, data rate and readout speed. A serial power scheme will be used for the pixel layers to reduce the material budget and power consumption in cables. New elements are required to operate and monitor a serially powered detector including a detector control system, constant current sources and front-end electronics with shunt regulators. Prototypes for all sections of the ITk pixel detector are built to verify the concept and operate multiple serial power chains as a system test. The evaluation of both the readout of multi-modules and mechanical integration are further aims of the prototyping campaign. In the contribution, results will be presented of this prototyping effort. Moreover, details and features of serial powering for full detector systems will be given

Evaluation of a Serial Powering Scheme and its Building Blocks for the ATLAS ITk Pixel Detector

The high luminosity upgrade for the Large Hadron Collider (LHC) at CERN requires a complete redesign of the current inner detectors of ATLAS and CMS. These new inner detectors will consist of all-silicon tracking detectors, combining multiple layers of silicon hybrid pixel modules and strip detectors. In the new pixel detectors conservative powering schemes are not feasible anymore. Instead serial powering has been chosen as a baseline powering scheme for both the future ATLAS and CMS pixel detectors. In serial powering, multiple detector modules are powered by a constant supply current. This new powering scheme provides challenges for the electrical and mechanical design, from the readout chip to system level considerations. The main building block of the serial powering scheme foreseen for the ATLAS ITk pixel detector is the shunt low dropout voltage regulator (Shunt-LDO). The Shunt-LDO generates the local supply voltages for each pixel module from the constant supply current while shunting any excess current not drawn by the readout chips. In this thesis the Shunt-LDO is extensively characterised and evaluated. The expanding feature set of the Shunt-LDO has been verified over several years of development and the radiation hardness of the regulator design in the 65 nm CMOS process node used for the ATLAS ITk pixel readout chips has been proven. The operation and performance of next-generation pixel readout chips using the Shunt-LDO was demonstrated using RD53A, a technology demonstrator for the future ATLAS and CMS pixel readout chips. An additional focus of this work is the large scale prototyping of serial powering. In the context of this work the Outer Barrel Demonstrator (OBD) program at CERN was commissioned and yielded first valuable experiences in operating a serially powered pixel detector with representative services and local supports. The OBD was the first prototype to operate multiple parallel, electrically coupled serial powering chains successfully. Finally a serial powering chain with pixel detector modules based on the next-generation readout chip, the RD53A, has been scoped, designed and set up in the context of this thesis with the goal to study low-level properties of serially powered detectors. This prototype, consisting of 8 RD53A quad chip modules with planar silicon sensors, demonstrated the ability to operate a serial powering chain with modules based on the next-generation readout chips without any performance deterioration

Development and Evaluation of Prototypes for the ATLAS ITk Pixel Detector

The ATLAS tracking system will be replaced by an all-silicon detector for the HL-LHC upgrade around 2025. The innermost five layers of the detector system will be pixel detector layers which will be most challenging in terms of radiation hardness, data rate and readout speed. A serial power scheme will be used for the pixel layers to reduce the radiation length and power consumption in cables. New elements are required to operate and monitor a serially powered detector including a detector control system, constant current sources and front-end electronics with shunt regulators. Prototypes for all subsystems are built to verify the concept and operate multiple serial power chains as a system test. The evaluation of both the readout of multi-modules and mechanical integration are further aims of the prototyping campaign. In the contribution, results will be presented of this prototyping effort. Moreover, details and features of serial powering for full detector systems will be given

Prototyping Serial Powering with RD53A and ITkPixV1.1

The high luminosity upgrade for the Large Hadron Collider at CERN requires a complete overhaul of the current inner detectors of ATLAS and CMS. These new detectors will consist of all-silicon tracking detectors. A serial powering scheme has been chosen in order to cope with the various constraints of the new detectors. In order to verify this new powering scheme and provide input for various system aspects, efforts are ongoing to set up a first larger prototype for serial powering using modules based on the new readout chips developed in 65 nm CMOS technology by the RD53 collaboration, RD53A and ITkPixV1. In particular, a serial powering stave consisting of up to 8 quad modules, either RD53A with planar sensor or ITkPixV1.1 without a sensor, has been set up in Bonn. This contribution covers the results obtained with RD53A modules and presents first measurements with a full ITkPixV1.1 serial powering chain, with emphasis on the electrical characterization of modules in a serial chain with representative services and power supplies

Stabilization and Protection of the Shunt-LDO regulator for the HL-LHC pixel detector upgrades

Serial powering is the baseline option for the pixel detectors in both the ATLAS and the CMS experiments targeting the phase II HL-LHC upgrade. The Shunt-LDO regulator is integrated in the front-end chips to generate the required supply voltages. A new compensation scheme has been developed to assure stable operation with large on-chip low-ESR (equivalent series resistance) load capacitances. A two-stage bandgap voltage reference circuit has been implemented to improve regulation performance. Security features have been added to protect against overvoltage and overload. Additional features have been added to allow regulator operation with small supply currents during the installation phase

Search for heavy neutral leptons in decays of W bosons using leptonic and semi-leptonic displaced vertices in s \sqrt{s} = 13 TeV pp collisions with the ATLAS detector

A search is performed for long-lived heavy neutral leptons (HNLs), produced through the decay of a W boson along with a muon or electron. Two channels are explored: a leptonic channel, in which the HNL decays into two leptons and a neutrino, and a semi-leptonic channel, in which the HNL decays into a lepton and a charged pion. The search is performed with 140 fb$^{−1}$ of $\sqrt{s}$ = 13 TeV proton-proton collision data collected by ATLAS during Run 2 of the Large Hadron Collider. No excess of events is observed; Dirac-like and Majorana-like HNLs with masses below 14.5 GeV and mixing coefficients as small as 10$^{−7}$ are excluded at the 95% confidence level. The results are interpreted under different assumptions on the flavour of the leptons from the HNL decays.[graphic not available: see fulltext

Configuration, Performance, and Commissioning of the ATLAS b-jet Triggers for the 2022 and 2023 LHC data-taking periods

In 2022 and 2023, the Large Hadron Collider producedapproximately two billion hadronic interactions each second frombunches of protons that collide at a rate of 40 MHz. The ATLAStrigger system is used to reduce this rate to a few kHz forrecording. Selections based on hadronic jets, their energy, andevent topology reduce the rate to (10) kHz whilemaintaining high efficiencies for important signatures resulting in b-quarks, but to reach the desired recording rate of hundreds ofHz, additional real-time selections based on the identification ofjets containing b-hadrons (b-jets) are employed to achieve lowthresholds on the jet transverse momentum at the High-Level Trigger.The configuration, commissioning, and performance of the real-timeATLAS b-jet identification algorithms for the early LHC Run 3collision data are presented. These recent developments providesubstantial gains in signal efficiency for critical signatures; forthe Standard Model production of Higgs boson pairs, a 50%improvement in selection efficiency is observed in final states withfour b-quarks or two b-quarks and two hadronically decaying τ-leptons

Search for vector-like leptons coupling to first- and second-generation Standard Model leptons in pp collisions at s \sqrt{s} = 13 TeV with the ATLAS detector

A search for pair production of vector-like leptons coupling to first- and second-generation Standard Model leptons is presented. The search is based on a dataset of proton-proton collisions at $\sqrt{s}$ = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 140 fb$^{−1}$. Events are categorised depending on the flavour and multiplicity of leptons (electrons or muons), as well as on the scores of a deep neural network targeting particular signal topologies according to the decay modes of the vector-like leptons. In each of the signal regions, the scalar sum of the transverse momentum of the leptons and the missing transverse momentum is analysed. The main background processes are estimated using dedicated control regions in a simultaneous fit with the signal regions to data. No significant excess above the Standard Model background expectation is observed and limits are set at 95% confidence level on the production cross-sections of vector-like electrons and muons as a function of the vector-like lepton mass, separately for SU(2) doublet and singlet scenarios. The resulting mass lower limits are 1220 GeV (1270 GeV) and 320 GeV (400 GeV) for vector-like electrons (muons) in the doublet and singlet scenarios, respectively.[graphic not available: see fulltext

Search for single-production of vector-like quarks decaying into Wb in the fully hadronic final state in pp collisions at s \sqrt{s} = 13 TeV with the ATLAS detector

A search for T and Y vector-like quarks produced in proton-proton collisions at a centre-of-mass energy of 13 TeV and decaying into Wb in the fully hadronic final state is presented. The search uses 139 fb$^{−1}$ of data collected by the ATLAS detector at the LHC from 2015 to 2018. The final state is characterised by a hadronically decaying W boson with large Lorentz boost and a b-tagged jet, which are used to reconstruct the invariant mass of the vector-like quark candidate. The main background is QCD multijet production, which is estimated using a data-driven method. Upon finding no significant excess in data, mass limits at 95% confidence level are obtained as a function of the global coupling parameter, κ. The observed lower limits on the masses of Y quarks with κ = 0.5 and κ = 0.7 are 2.0 TeV and 2.4 TeV, respectively. For T quarks, the observed mass limits are 1.4 TeV for κ = 0.5 and 1.9 TeV for κ = 0.7.[graphic not available: see fulltext