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Previous studies have shown how discontinuous resin formats can increase the robustness of Vacuum Bag Only (VBO) prepregs. Current formats of this discontinuous resin format, dubbed USCPreg, all rely on a discontinuous film being applied on a fiber bed using only pressure. However, efforts are currently being undertaken to apply the discontinuous resin to the fiber bed directly, without a separate filming step. These methods should allow broader and more diverse characteristics of the prepreg, and allow a reduction in bulk factor, customization of the resin distribution, and potentially enable the production of prepreg “on demand.” To understand how applying discontinuous resin to a dry fiber bed at temperatures suitable for resin deposition may affect the final distribution, small-scale experiments were conducted. A fluid with controlled viscosity, matching the viscosity of epoxy resin during hotmelt processing, was used to minimize variability. The experiments consisted of a sessile droplet of facsimile fluid being deposited on the surface of a single ply of reinforcement. The spread of the fluid was then recorded, using a goniometer as well as a standard camera. Post-processing of these recordings was performed to obtain the spreading of the fluid in three directions: in the plane directions and the out-of-plane direction. The fluid was constant, a 30Pa.s rheological standard, but the reinforcement was varied to determine how the fluid interacted with different reinforcements. Macro-scale changes, such as fabric weave and fabric areal weight, and micro-scale parameters, such as tow width and fiber size, were varied to observe their effects on fluid distribution. The experiments yielded maximum in-plane spread distance, time for the resin to fully impregnate into the fibers, and aspect ratio of spreading, particularly for non-symmetric weaves. The results can be used to guide how the resin is deposited on different reinforcements, in order to achieve a resin distribution that will consistently yield high-quality parts. In addition, it is possible these observations can be applied to resin flow in standard continuous film prepreg, such as predicting the final degree of impregnation. 

Previous studies have shown how discontinuous resin formats can increase the robustness of Vacuum Bag Only (VBO) prepregs. Current formats of this discontinuous resin format, dubbed USCPreg, all rely on a discontinuous film being applied on a fiber bed using only pressure. However, efforts are currently being undertaken to apply the discontinuous resin to the fiber bed directly, without a separate filming step. These methods should allow broader and more diverse characteristics of the prepreg, and allow a reduction in bulk factor, customization of the resin distribution, and potentially enable the production of prepreg “on demand.” To understand how applying discontinuous resin to a dry fiber bed at temperatures suitable for resin deposition may affect the final distribution, small-scale experiments were conducted. A fluid with controlled viscosity, matching the viscosity of epoxy resin during hotmelt processing, was used to minimize variability. The experiments consisted of a sessile droplet of facsimile fluid being deposited on the surface of a single ply of reinforcement. The spread of the fluid was then recorded, using a goniometer as well as a standard camera. Post-processing of these recordings was performed to obtain the spreading of the fluid in three directions: in the plane directions and the out-of-plane direction. The fluid was constant, a 30Pa.s rheological standard, but the reinforcement was varied to determine how the fluid interacted with different reinforcements. Macro-scale changes, such as fabric weave and fabric areal weight, and micro-scale parameters, such as tow width and fiber size, were varied to observe their effects on fluid distribution. The experiments yielded maximum in-plane spread distance, time for the resin to fully impregnate into the fibers, and aspect ratio of spreading, particularly for non-symmetric weaves. The results can be used to guide how the resin is deposited on different reinforcements, in order to achieve a resin distribution that will consistently yield high-quality parts. In addition, it is possible these observations can be applied to resin flow in standard continuous film prepreg, such as predicting the final degree of impregnation. 

This report presents a comprehensive collection of searches for new physics performed by the ATLAS Collaboration during the Run~2 period of data taking at the Large Hadron Collider, from 2015 to 2018, corresponding to about 140~$$^{-1}$$ of $$\sqrt{s}=13$$~TeV proton--proton collision data. These searches cover a variety of beyond-the-standard model topics such as dark matter candidates, new vector bosons, hidden-sector particles, leptoquarks, or vector-like quarks, among others. Searches for supersymmetric particles or extended Higgs sectors are explicitly excluded as these are the subject of separate reports by the Collaboration. For each topic, the most relevant searches are described, focusing on their importance and sensitivity and, when appropriate, highlighting the experimental techniques employed. In addition to the description of each analysis, complementary searches are compared, and the overall sensitivity of the ATLAS experiment to each type of new physics is discussed. Summary plots and statistical combinations of multiple searches are included whenever possible. 

The ATLAS experiment has developed extensive software and distributed computing systems for Run 3 of the LHC. These systems are described in detail, including software infrastructure and workflows, distributed data and workload management, database infrastructure, and validation. The use of these systems to prepare the data for physics analysis and assess its quality are described, along with the software tools used for data analysis itself. An outlook for the development of these projects towards Run 4 is also provided. 

Abstract The ATLAS tile calorimeter (TileCal) is the hadronic sampling calorimeter covering the central region of the ATLAS detector at the Large Hadron Collider (LHC). This paper gives an overview of the calorimeter’s operation and performance during the years 2015–2018 (Run 2). In this period, ATLAS collected proton–proton collision data at a centre-of-mass energy of 13 TeV and the TileCal was 99.65% efficient for data-taking. The signal reconstruction, the calibration procedures, and the detector operational status are presented. The performance of two ATLAS trigger systems making use of TileCal information, the minimum-bias trigger scintillators and the tile muon trigger, is discussed. Studies of radiation effects allow the degradation of the output signals at the end of the LHC and HL-LHC operations to be estimated. Finally, the TileCal response to isolated muons, hadrons and jets from proton–proton collisions is presented. The energy and time calibration methods performed excellently, resulting in good stability and uniformity of the calorimeter response during Run 2. The setting of the energy scale was performed with an uncertainty of 2%. The results demonstrate that the performance is in accordance with specifications defined in the Technical Design Report. 

Abstract This paper reports a summary of searches for a fermionic dark matter candidate in the context of theoretical models characterised by a mediator particle exchange in thes-channel. The data sample considered consists ofppcollisions delivered by the Large Hadron Collider during its Run 2 at a centre-of-mass energy of$$\sqrt{s} = 13\,\textrm{TeV}$$ $\sqrt{s}=13\text{TeV}$and recorded by the ATLAS detector, corresponding to up to 140 fb$$^{-1}$$ $_{}^{-1}$. The interpretations of the results are based on simplified models where the new mediator particles can be spin-0, with scalar or pseudo-scalar couplings to fermions, or spin-1, with vector or axial-vector couplings to fermions. Exclusion limits are obtained from various searches characterised by final states with resonant production of Standard Model particles, or production of Standard Model particles in association with large missing transverse momentum. 

Structure and paleogeographic history of the northern Ninetyeast Ridge International Ocean Discovery Program (IODP) Site U1443 is located ~100 m southeast of Ocean Drilling Program (ODP) Leg 121 Site 758 on the crest of the Ninetyeast Ridge and is a redrill of Site 758 (Figure F1). The Ninetyeast Ridge represents the trace of the Kerguelen/Ninetyeast hotspot prior to middle Eocene rifting (Shipboard Scientific Party, 1989a). As a result of northward movement, Site U1443 moved from temperate southern latitudes during the Campanian, to ~5°S near the Oligocene/Miocene boundary, and to its present location of 5°N in the southernmost Bay of Bengal. The site has been within 10° of the Equator for the past 35 My (Shipboard Scientific Party, 1989a). The ridge-top location has prevented the deposition of sedimentary sequences typically associated with fan transport processes. 

International Ocean Discovery Program (IODP) Site U1446 is located in the Mahanadi offshore basin on the eastern margin of India (Figure F1). This sedimentary basin extends both onshore and offshore and was formed during the Late Jurassic rifting of Gondwana (Sastri et al., 1981; Subrahmanyam et al., 2008). Today, the Mahanadi River basin (19°21′ to 23°35′N, 80°30′ to 86°50′E; ~1.42 × 105 km2) drains a catchment composed of late Archaean and early Proterozoic granite batholiths and gneisses from the Eastern Ghats (~56%); Gondwana-age limestones, shales, and sandstones (~39%); and recent alluvium (~5%) (Mazumdar et al., 2015; Rickers et al., 2001), including one of the richest mineral belts on the Indian subcontinent. This mineralization results in higher concentrations of trace metals such as Fe, Cu, Zn, and Pb in suspended river sediments compared to other rivers in peninsular India (Chakrapani and Subramanian, 1990b). Kaolinite, chlorite, quartz, dolomite, and minor montmorillonite and illite are characteristic components of suspended sediments discharged by the Mahanadi River into the Bay of Bengal (Subramanian, 1980; Chakrapani and Subramanian, 1990b). 

The main scientific objective of International Ocean Discovery Program (IODP) Expedition 353 was to analyze the variability of precipitation and runoff in the Bay of Bengal on suborbital to orbital timescales. To achieve this objective, site locations were selected according to their proximity to the main sources of freshwater feeding the northern Bay of Bengal, including the Mahanadi River and the Ganges-Brahmaputra river complex, and the Andaman Sea, including the Irrawaddy and Salween river systems. 

International Ocean Discovery Program (IODP) Expedition 353 (29 November 2014–29 January 2015) drilled six sites in the Bay of Bengal, recovering 4280 m of sediments during 32.9 days of on-site drilling. Recovery averaged 97%, including coring with the advanced piston corer, half-length advanced piston corer, and extended core barrel systems. The primary objective of Expedition 353 is to reconstruct changes in Indian monsoon circulation since the Miocene at tectonic to centennial timescales. Analysis of the sediment sections recovered will improve our understanding of how monsoonal climates respond to changes in forcing external to the Earth’s climate system (i.e., insolation) and changes in forcing internal to the Earth’s climate system, including changes in continental ice volume, greenhouse gas concentrations, sea level, and the ocean-atmosphere exchange of energy and moisture. All of these mechanisms play critical roles in current and future climate change in monsoonal regions. The primary signal targeted is the exceptionally low salinity surface waters that result, in roughly equal measure, from both direct summer monsoon precipitation above the Bay of Bengal and runoff from the numerous large river basins that drain into the Bay of Bengal. Changes in rainfall and surface ocean salinity are captured and preserved in a number of chemical, physical, isotopic, and biological components of sediments deposited in the Bay of Bengal. Expedition 353 sites are strategically located in key regions where these signals are the strongest and best preserved. Salinity changes at IODP Sites U1445 and U1446 (northeast Indian margin) result from direct precipitation as well as runoff from the Ganges-Brahmaputra river complex and the many river basins of peninsular India. Salinity changes at IODP Sites U1447 and U1448 (Andaman Sea) result from direct precipitation and runoff from the Irrawaddy and Salween river basins. IODP Site U1443 (Ninetyeast Ridge) is an open-ocean site with modern surface water salinity very near to the global mean but is documented to have recorded changes in monsoonal circulation over orbital to tectonic timescales. This site serves as an anchor for establishing the extent to which the north to south (19°N to 5°N) salinity gradient changes over time.