Search results for "Detectors"

Evidence for the associated production of a W boson and a top quark in ATLAS at √s = 7 TeV

2012

This Letter presents evidence for the associated production of a W boson and a top quark using 2.05 fb[superscript −1] of pp collision data at √s = 7 TeV accumulated with the ATLAS detector at the LHC. The analysis is based on the selection of the dileptonic final states with events featuring two isolated leptons, electron or muon, with significant transverse missing momentum and at least one jet. An approach based on boosted decision trees has been developed to improve the discrimination of single top-quark Wt events from background. A template fit to the final classifier distributions is performed to determine the cross-section. The result is incompatible with the background-only hypothes…

Advanced Virgo Status

2015

Abstract The detection of a gravitational wave signal in September 2015 by LIGO interferometers, announced jointly by LIGO collaboration and Virgo collaboration in February 2016, opened a new era in Astrophysics and brought to the whole community a new way to look at - or “listen” to - the Universe. In this regard, the next big step was the joint observation with at least three detectors at the same time. This configuration provides a twofold benefit: it increases the signal-to-noise ratio of the events by means of triple coincidence and allows a narrower pinpointing of GW sources, and, in turn, the search for Electromagnetic counterparts to GW signals. Advanced Virgo (AdV) is the second ge…

Photodétecteurs UV à base GaAlN

2004

Trigger and aperture of the surface detector array of the Pierre Auger Observatory

2010

The surface detector array of the Pierre Auger Observatory consists of 1600 water-Cherenkov detectors, for the study of extensive airshowers (EAS) generated by ultra-high-energy cosmic rays. We describe the trigger hierarchy, from the identification of candidates howers at the level of a single detector, amongst a large background (mainly random single cosmic ray muons), up to the selection of real events and the rejection of random coincidences. Such trigger makes the surface detector array fully efficient for the detection of EAS with energy above 3 x 1018 eV, for all zenith angles between 03 and 603, independently of the position of the impact point and of the mass of the primary particl…

Implementation and performance of the ATLAS second level jet trigger

2008

ATLAS is one of the four major LHC experiments, designed to cover a wide range of physics topics. In order to cope with a rate of 40 MHz and 25 interactions per bunch crossing, the ATLAS trigger system is divided in three different levels. The first one (LVL1, hardware based) identifies signatures in 2 microseconds that are confirmed by the the following trigger levels (software based). The Second Level Trigger (LVL2) only looks at a region of the space around the LVL1 signature (called Region of Interest or ROI), confirming/rejecting the event in about 10 ms, while the Event Filter (Third Level Trigger, EF) has potential full event access and larger processing times, of the order of 1 s. T…

The Upgrade of the ATLAS Level-1 Central Trigger Processor

2013

The ATLAS Level-1 Central Trigger Processor (CTP) combines information from calorimeter and muon trigger processors as well as other sources and makes the final Level-1 Accept (L1A) decision. Due to the increasing luminosity of the LHC and the growing demands of physics and monitoring placed on the ATLAS Level-1 trigger system, the current CTP has reached its design limits. Therefore and in order to provide some margin for future operation, the CTP will be upgraded during the LHC shutdown of 2013/14.

DEPFET Active Pixel Detectors for a Future Linear e(+)e(-) Collider

2013

arXiv:1212.2160v1.-- et al.

The Voyage of Metals in the Universe from Cosmological to Planetary Scales: the need for a Very High-Resolution, High Throughput Soft X-ray Spectrome…

2019

Metals form an essential part of the Universe at all scales. Without metals we would not exist, and the Cosmos would look completely different. Metals are primarily born through nuclear processes in stars. They leave their cradles through winds or explosions, and then start their journey through space. This can lead them in and out of astronomical objects on all scales, ranging from comets, planets, stars, entire galaxies, groups and clusters of galaxies to the largest structures of the Universe. Their wanderings are fundamental in determining how these objects, and the entire universe, evolve. In addition, their bare presence can be used to trace what these structures look like. The scope …

Global Trigger Technological Demonstrator for ATLAS Phase-II upgrade

2020

ATLAS detector at the LHC will undergo a major Phase-II upgrade for the High Luminosity LHC. The upgrade affects all major ATLAS systems, including the Trigger and Data Acquisition systems. As part of the Level-0 Trigger System, the Global Trigger uses full-granularity calorimeter cells to perform algorithms, refines the trigger objects and applies topological requirements. The Global Trigger uses a Global Common Module as the building block of its design. To achieve a high input and output bandwidth and substantial processing power, the Global Common Module will host the most advanced FPGAs and optical modules. In order to evaluate the new generation of optical modules and FPGAs running at…

Combination of Searches for Invisible Higgs Boson Decays with the ATLAS Experiment

2019

Dark matter particles, if sufficiently light, may be produced in decays of the Higgs boson. This Letter presents a statistical combination of searches for H → invisible decays where H is produced according to the standard model via vector boson fusion, Z(ℓℓ)H, and W/Z(had)H, all performed with the ATLAS detector using 36.1  fb⁻¹ of pp collisions at a center-of-mass energy of √s = 13  TeV at the LHC. In combination with the results at √s = 7 and 8 TeV, an exclusion limit on the H → invisible branching ratio of 0.26(0.17-0.05+0.07) at 95% confidence level is observed (expected).