The ABC130 barrel module prototyping programme for the ATLAS strip tracker

For the Phase-II Upgrade of the ATLAS Detector, its Inner Detector, consisting of silicon pixel, silicon strip and transition radiation sub-detectors, will be replaced with an all new 100 % silicon tracker, composed of a pixel tracker at inner radii and a strip tracker at outer radii. The future ATLAS strip tracker will include 11,000 silicon sensor modules in the central region (barrel) and 7,000 modules in the forward region (end-caps), which are foreseen to be constructed over a period of 3.5 years. The construction of each module consists of a series of assembly and quality control steps, which were engineered to be identical for all production sites. In order to develop the tooling and procedures for assembly and testing of these modules, two series of major prototyping programs were conducted: an early program using readout chips designed using a 250 nm fabrication process (ABCN-25) and a subsequent program using a follow-up chip set made using 130 nm processing (ABC130 and HCC130 chips). This second generation of readout chips was used for an extensive prototyping program that produced around 100 barrel-type modules and contributed significantly to the development of the final module layout. This paper gives an overview of the components used in ABC130 barrel modules, their assembly procedure and findings resulting from their tests.Comment: 82 pages, 66 figure

Searches for dark matter and single top-quarks with the ATLAS experiment

Dark matter (DM) remains one of the unrevealed mysteries of the universe. Even though it constitutes ∼ 85% of the matter, considerably little is known about DM, despite its significant influence on the dynamics of galaxies and the expansion of the universe. The search for DM at colliders marks an important pillar in exploring all possible realisations of DM. A search for DM particles with the ATLAS experiment at the LHC is presented in this thesis. The full run-II dataset of sqrt(s) = 13 TeV proton-proton collisions with an integrated luminosity of 139 fb-1 collected from 2015 to 2018 is used. A model with an extended Higgs-sector is probed in the search. In this 2HDM+a model, a second Higgs doublet, a pseudo-scalar DM mediator and a fermionic DM particle are added to the Standard Model of particle physics (SM). DM particles produced in association with a top-quark and a W -boson are searched for. The top-quark decays into a W-boson and a b-quark. This gives a total of two W-bosons in signal events. Both of these can decay into quarks or leptons. Depending on the decays of the W-bosons, the final state of this search is characterised by zero, one or two charged leptons. Three analysis channels are defined according to the charged lepton multiplicity and referred to as 0L, 1L and 2L channel. The search presented in this thesis focusses on the 1L channel. In addition, all final states are statistically combined to provide the most stringent exclusion limits in terms of 2HDM+a model based DM models. The 1L channel exploits that one of the W-bosons can, if decaying hadronically and having a relatively high-pT, be reconstructed in a large-radius jet and be identified using a procedure called W-tagging. This significantly increases the signal-to-background ratio. Selected events must have high missing transverse momentum due to the elusive nature of DM particles and at least one b-tagged small-radius jet. Consistency between the SM prediction and the data is observed and exclusion limits at 95 % CL on the normalisation of BSM signals are derived. The analysis of the full run-II dataset and the statistical combination of all final states constrain large areas of the parameter space. Masses ma up to 400 GeV as well as masses mH± below 300 GeV and beyond 2000 GeV and values of tan β up to 2.2 are excluded. Interesting opportunities to further explore challenging corners of the parameter space arise, e.g. extending the sensitivity at high values of tan β

The design and layout of the Phase-II upgrade of the Inner tracker of the ATLAS experiment

In the high luminosity era of the Large Hadron Collider (HL-LHC), the instantaneous luminosity is expected to reach unprecedented values, resulting in about 200 proton-proton interactions in a typical bunch crossing. To cope with the resultant increase in occupancy, bandwidth and radiation damage, the ATLAS Inner Detector will be replaced by an all-silicon system, the Inner Tracker (ITk), aiming to provide tracking coverage up to |η|<4. The Technical Design Reports (TDR) for the strip and pixel subsystems were published in 2017 and 2018 respectively. Since their publication, the ITk design has undergone further refinement, in particular for the pixel subsystem, addressing the then-pending design choices in several areas and accommodating updated engineering requirements. In addition, the simulation model of the detector has become more realistic, leading to updated estimates of the material budget. In this presentation an overview of the updated layout is presented and the resultant expected tracking performance discussed

Analysis of testbeam data with inclined pALPIDE-3 chips

The ALICE ITS upgrade is planning to use monolithic pixel sensors. The behaviour of the latest prototype for different angles of incidence was investigated in testbeam measurements between July and September 2016 at the Proton Synchrotron (PS) at CERN. When trying to analyse the data, problems with the analysis framework EUTelescope were noticed. This report describes, how these problems could be resolved and presents the results of the data analysis. An overview of the ITS upgrade and MAPS is also given

The ABC130 barrel module prototyping programme for the ATLAS strip tracker

For the Phase-II Upgrade of the ATLAS Detector [1], its Inner Detector, consisting of silicon pixel, silicon strip and transition radiation sub-detectors, will be replaced with an all new 100% silicon tracker, composed of a pixel tracker at inner radii and a strip tracker at outer radii. The future ATLAS strip tracker will include 11,000 silicon sensor modules in the central region (barrel) and 7,000 modules in the forward region (end-caps), which are foreseen to be constructed over a period of 3.5 years. The construction of each module consists of a series of assembly and quality control steps, which were engineered to be identical for all production sites. In order to develop the tooling and procedures for assembly and testing of these modules, two series of major prototyping programs were conducted: an early program using readout chips designed using a 250 nm fabrication process (ABCN-250) [2,2] and a subsequent program using a follow-up chip set made using 130 nm processing (ABC130 and HCC130 chips). This second generation of readout chips was used for an extensive prototyping program that produced around 100 barrel-type modules and contributed significantly to the development of the final module layout. This paper gives an overview of the components used in ABC130 barrel modules, their assembly procedure and findings resulting from their tests

Observation of WWW Production in pp Collisions at √s = 13 TeV with the ATLAS Detector

This Letter reports the observation of W W W production and a measurement of its cross section using 139     fb − 1 of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. Events with two same-sign leptons (electrons or muons) and at least two jets, as well as events with three charged leptons, are selected. A multivariate technique is then used to discriminate between signal and background events. Events from W W W production are observed with a significance of 8.0 standard deviations, where the expectation is 5.4 standard deviations. The inclusive W W W production cross section is measured to be 820 ± 100   ( stat ) ± 80   ( syst )     fb , approximately 2.6 standard deviations from the predicted cross section of 511 ± 18     fb calculated at next-to-leading-order QCD and leading-order electroweak accuracy