Installing the ATLAS calorimeter — The eight toroid magnets can be seen surrounding the calorimeter that is later moved into the middle of the detector. This calorimeter will measure the energies of particles produced when protons collide in the centre of the detector. (Image: CERN)

Bends particles around the various layers of detector systems

By bending the trajectories of charged particles, ATLAS can measure their momentum and charge. This is done using two different types of superconducting magnet systems – solenoidal and toroidal. These impressive systems are cooled to about 4.5 K (–268°C) in order to provide the necessary strong magnetic fields.

The main sections of the magnet system are: Central Solenoid Magnet, Barrel Toroid and End-cap Toroids.

Central Solenoid Magnet

The ATLAS solenoid surrounds the inner detector at the core of the experiment. This powerful magnet is 5.8 m long, 2.56 m in diameter and weighs over 5 tonnes. It provides a 2 Tesla magnetic field in just 4.5 cm thickness. This is achieved by embedding over 9 km of niobium-titanium superconductor wires into strengthened, pure aluminum strips, thus minimising possible interactions between the magnet and the particles being studied.

Bends charged particles for momentum measurement
5.8 m long, 2.56 m outer diameter, 4.5 cm thick
5 tonne weight
2 tesla (T) magnetic field with a stored energy of 38 megajoules (MJ)
9 km of superconducting wire
Nominal current: 7.73 kiloampere (kA)

Toroid Magnet

The ATLAS toroids use a series of eight coils to provide a magnetic field of up to 3.5 Tesla, used to measure the momentum of muons. There are three toroid magnets in ATLAS: two at the ends of the experiment, and one massive toroid surrounding the centre of the experiment.

At 25.3 m in length, the central toroid is the largest toroidal magnet ever constructed. It is unique in particle physics and an iconic element of ATLAS. It uses over 56 km of superconducting wire and weighs about 830 tonnes. The end-cap toroids extend the magnetic field to particles leaving the detector close to the beam pipe. Each end-cap is 10.7 m in diameter and weighs 240 tonnes

Installation of the first of the big wheels of the ATLAS muon spectrometer, a thin gap chamber (TGC) wheel — The muon spectrometer will include four big moving wheels at each end, each measuring 25 metres in diameter. Of the eight wheels in total, six will be composed of thin gap chambers for the muon trigger system and the other two will consist of monitored drift tubes (MDTs) to measure the position of the muons (Image: CERN)

Identifies and measures the momenta of muons

The outer layer of the ATLAS experiment is made of muon detectors. They identify and measure the momenta of muons – particles similar to electrons but 200 times heavier, which allows them to cross the thick layers of the ATLAS Calorimeters.

Five different detector technologies are used: Thin Gap Chambers, Resistive Plate Chambers, Monitored Drift Tubes, Small-Strip Thin-Gap Chambers and Micromegas.

Precision Detectors

The precision detectors of the Muon Spectrometer are able to determine the position of a muon, to an accuracy of less than a 10th of a millimetre!

Monitored Drift Tube (MDTs) detectors are composed of 3 cm wide aluminium tubes filled with a gas mixture. Muons pass through the tubes, knocking electrons out of the gas. These then drift to a wire at the tube’s centre to induce a signal. Over 380,000 aluminium tubes are stacked up in several layers in order to precisely trace the trajectory of each muon.

Fast-Response Detectors

ATLAS uses fast-response detectors to quickly select collision events that are potentially interesting for physics analysis. They make this decision within 2.5 μs (400,000th of a second).

The Resistive Plate Chambers (RPCs) surround the central region of the ATLAS experiment. They consist of pairs of parallel plastic plates at an electric potential difference, separated by a gas volume. Thin Gap Chambers (TGCs) are found at the ends of the ATLAS experiment and consist of parallel 30 μm wires in a gas mixture. Both chambers detect muons when they ionise the gas mixture and generate a signal.

Micromegas and Small-Strip Thin-Gap Chambers (sTGCs) are two additional detector technologies specially designed for high-intensity LHC collisions. These detectors can track muons in high-density areas on either side of the experiment close to the LHC beam pipe, both quickly and with high precision.

The combined data from fast-response detectors gives a coarse measurement of a muon’s momentum, allowing ATLAS to choose whether to keep or discard a collision event.

Measures the energy a particle loses as it passes through the detector

They are designed to absorb most of the particles coming from a collision, forcing them to deposit all of their energy and stop within the detector. ATLAS calorimeters consist of layers of an “absorbing” high-density material that stops incoming particles, interleaved with layers of an “active” medium that measures their energy.

Electromagnetic calorimeters measure the energy of electrons and photons as they interact with matter. Hadronic calorimeters sample the energy of hadrons (particles that contain quarks, such as protons and neutrons) as they interact with atomic nuclei. Calorimeters can stop most known particles except muons and neutrinos.

The components of the ATLAS calorimetry system are: the Liquid Argon (LAr) Calorimeter and the Tile Hadronic Calorimeter.

Liquid Argon Calorimeter

The Liquid Argon (LAr) Calorimeter surrounds the ATLAS Inner Detector and measures the energy of electrons, photons and hadrons. It features layers of metal (either tungsten, copper or lead) that absorb incoming particles, converting them into a “shower” of new, lower energy particles. These particles ionise liquid argon sandwiched between the layers, producing an electric current that is measured. By combining all of the detected currents, physicists can determine the energy of the original particle that hit the detector.

The central region of the calorimeter is specially designed to identify electrons and photons. It features a characteristic accordion structure, with a honeycomb pattern, to ensure that no particle escapes unchallenged.

To keep the argon in liquid form, the calorimeter is kept at -184°C. Specially-designed, vacuum-sealed cylinders of cables bring the electronic signals from the cold liquid argon to the warm area where the readout electronics are located.

Tile Hadronic Calorimeter

The Tile Calorimeter surrounds the LAr calorimeter and measures the energy of hadronic particles, which do not deposit all of their energy in the LAr Calorimeter. It is made of layers of steel and plastic scintillating tiles. As particles hit the layers of steel, they generate a shower of new particles. The plastic scintillators in turn produce photons, which are converted into an electric current whose intensity is proportional to the original particle’s energy.

The Tile Calorimeter is made up of about 420,000 plastic scintillator tiles working in sync. It is the heaviest part of the ATLAS experiment, weighing almost 2900 tonnes!

Combining two major ATLAS inner detector components — The semiconductor tracker is inserted into the transition radiation tracker for the ATLAS experiment at the LHC. These make up two of the three major components of the inner detector. They will work together to measure the trajectories produced in the proton-proton collisions at the centre of the detector when the LHC is switched on in 2008. (Image: CERN)

It is the first part of ATLAS to see the decay products of the collisions

It is very compact and highly sensitive. It consists of three different systems of sensors all immersed in a magnetic field parallel to the beam axis. The Inner Detector measures the direction, momentum, and charge of electrically-charged particles produced in each proton-proton collision.

The main components of the Inner Detector are: Pixel Detector, Semiconductor Tracker (SCT), and Transition Radiation Tracker (TRT).

Pixel Detector

Located just 3.3 cm from the LHC beam line, the Pixel Detector is the first point of detection in the ATLAS experiment. It is made up of four layers of silicon pixels, with each pixel smaller than a grain of sand. As charged particles burst out from the collision point, they leave behind small energy deposits in the Pixel Detector. These signals are measured with a precision of almost 10 μm to determine the origin and momentum of the particle. The Pixel Detector is incredibly compact, with over 92 million pixels and almost 2000 detector elements.

92 million pixels (92 million electronic channels).
Silicon area approx. 1.9m². 15 kW power consumption
Pixel size 50 x 400μm² for the external layers and 50 x 250 μm²for the innermost layer (IBL)
4-barrel layers with 1736 sensor modules
3 disks in each end-cap with 288 modules

Semiconductor Tracker

The Semiconductor Tracker surrounds the Pixel Detector and is used to detect and reconstruct the tracks of charged particles produced during collisions. It consists of over 4,000 modules of 6 million “micro-strips” of silicon sensors. Its layout is optimised such that each particle crosses at least four layers of silicon. This allows scientists to measure particle tracks with a precision of up to 25 μm - that’s less than half the width of a human hair!

4,088 two-sided modules and over 6 million implanted readout strips (6 million channels)
60m² of silicon distributed over 4 cylindrical barrel layers and 18 planar endcap discs
Readout strips every 80μm on the silicon

Transition Radiation Tracker

The third and final layer of the Inner Detector is the Transition Radiation Tracker (TRT). Unlike its neighbouring sub-detectors, the TRT is made up of 300,000 thin-walled drift tubes (or “straws”). Each straw is just 4 mm in diameter, with a 30 μm gold-plated tungsten wire in its centre. The straws are filled with a gas mixture. As charged particles cross through the straws, they ionise the gas to create a detectable electric signal. This is used to reconstruct their tracks and, owing to the so-called transition radiation, provides information on the particle type that flew through the detector, i.e. if it is an electron or pion.

350,000 read-out channels
Volume 12m³
Straw tubes with 4mm diameter, with centred 0.03mm diameter gold-plated tungsten wire
50,000 straws in Barrel, each straw 144 cm long.
250,000 straws in both endcaps, each straw 39 cm long
Precision measurement of 0.17 mm (particle track to wire)

The first ATLAS inner detector end-cap after complete insertion within the Liquid Argon Cryostat.

The installation of the ATLAS inner detector end-cap C.

Inner — An ATLAS inner detector end-cap is placed in its cryostat. The instrumentation housed inside the inner end-cap must be kept cool to avoid thermal noise. This cooling is achieved on ATLAS by placing the end-cap inside a liquid argon cryostat. The end-cap measures particles that are produced close to the direction of the beam pipe and would otherwise be missed.

This colorful 3D animation is an excerpt from the film "ATLAS-Episode II, The Particles Strike Back." Shot with a bug's eye view of the inside of the detector. The viewer is taken on a tour of the inner workings of the transitional radiation tracker within the ATLAS detector. Subjects covered include what the tracker is used to measure, its structure, what happens when particles pass through the tracker, how it distinguishes between different types of particles within it. (Video: CERN)

The largest volume detector ever constructed for a particle collider

ATLAS has the dimensions of a cylinder, 46m long, 25m in diameter, and sits in a cavern 100m below ground. The ATLAS detector weighs 7,000 tonnes, similar to the weight of the Eiffel Tower.

The detector itself is a many-layered instrument designed to detect some of the tiniest yet most energetic particles ever created on earth. It consists of six different detecting subsystems wrapped concentrically in layers around the collision point to record the trajectory, momentum, and energy of particles, allowing them to be individually identified and measured. A huge magnet system bends the paths of the charged particles so that their momenta can be measured as precisely as possible.

Beams of particles travelling at energies up to seven trillion electron-volts, or speeds up to 99.999999% that of light, from the LHC collide at the centre of the ATLAS detector producing collision debris in the form of new particles which fly out in all directions. Over a billion particle interactions take place in the ATLAS detector every second, a data rate equivalent to 20 simultaneous telephone conversations held by every person on the earth. Only one in a million collisions are flagged as potentially interesting and recorded for further study. The detector tracks and identifies particles to investigate a wide range of physics, from the study of the Higgs boson and top quark to the search for extra dimensions and particles that could make up dark matter.

Take a virtual walk

Outstanding Achievement Awards

The Outstanding Achievement Awards give recognition to excellent contributions made to the collaboration. Nominations come from across the collaboration, in areas such as technical coordination, detector systems, as well as activity areas including upgrade, combined performance and outreach. Winners are selected annually by the Collaboration Board Chair Advisory Group.

2024 Outstanding Achievement Award Winners

The ATLAS Outstanding Achievement Award winners for 2024 are:

Luca Canali (CERN) for outstanding contributions to the ATLAS database infrastructure.
Jackson Barr (University College London), Alexander Froch (Albert-Ludwigs-Universität Freiburg), Philipp Gadow (CERN), Dan Guest (Humboldt University Berlin), Nilotpal Kakati (Weizmann Institute of Science), Dmitrii Kobylianskii (Weizmann Institute of Science), Nikita Ivvan Pond (University College London), Samuel Van Stroud (University College London) for outstanding contributions to heavy flavour tagging algorithms based on Graph Neural Networks.
Liang Guan (Michigan), Ioannis Mesolongitis (University of West Attica), Michelle Solis (University of Arizona), Aaron White (Harvard University) for understanding the problem of randomly dropping e-links in the NSW and for finding a very effective mitigation for this problem.
Jakub Kremer (DESY), Agnieszka Ogrodnik (Charles University), Martin Rybar (Charles University) for outstanding contributions to the Heavy Ions operation and trigger.
Koji Nakamura (KEK), Hideyuki Oide (KEK), Manabu Togawa (KEK) for outstanding contributions to the ITk Pixel project in sensor production, hybridisation and module assembly.
Johannes Junggeburth (University of Massachusetts Amherst), Patrick Scholer (Carleton University) for outstanding contributions to the Run 3 muon software.
Sara Alderweireldt (University of Edinburgh), Rafal Bielski (University of Oregon), Francesco Giuli (CERN), Ralf Gugel (University of Mainz), Claudia Merlassino (University of Udine), Stefanie Morgenstern (CERN), Gabriel Palacino (Indiana University), Aleksandra Poreba (CERN), Antonia Strubig (Stockholm University), Daniele Zanzi (Albert-Ludwigs-Universität Freiburg) for outstanding contributions to the Trigger operation.
Julien Maurer (Bucharest IFIN-HH) for outstanding contributions to the ATLAS prompt reconstruction operation.
Anthony Affolder (UC Santa Cruz), Ian Dyckes (Berkeley LBNL), Vitaliy Fadeyev (UC Santa Cruz), Cole Helling (University of British Columbia, Vancouver), Jacob Wayne Johnson (UC Santa Cruz), Matthew Kurth (Beijing IHEP), Masahiro Morii (Harvard University), Peter Phillips (Rutherford Appleton Laboratory), Luise Poley (TRIUMF), Craig Sawyer (Rutherford Appleton Laboratory) for outstanding contributions to the identification of the vibrational source of cold noise on ITk Strip modules.

See the News Article on the 2024 Awards

2022 Outstanding Achievement Award Winners

The ATLAS Outstanding Achievement Award winners for 2022 are:

Christos Anastopoulos (University of Sheffield) for outstanding contribution to the preparation and ongoing development of the offline reconstruction for Run 3 and beyond.
Rhys Owen (Rutherford Appleton Laboratory) for outstanding contributions to the commissioning of the Level-1 Calorimeter Trigger for Run-3.
Marco Ciapetti (CERN) for outstanding contributions to the ATLAS detector cabling activities in LS2 and planning for LS3.
Fernando Carrio Argos (Centro Mixto Universidad de Valencia, University of the Witwatersrand), Jalal Abdallah (University of Texas at Arlington) for outstanding contributions to the integration of the TileCal HL-LHC Demonstrator into the ATLAS overall TDAQ system.
Tadej Novak (DESY) for outstanding contributions to the integration of the Upgrade Software.
Georges Aad (Aix-Marseille Université), Fatih Bellachia (Université Savoie Mont Blanc), Nicolas Chevillot (Université Savoie Mont Blanc), Yuji Enari (University of Tokyo), Sylvain Lafrasse (Université Savoie Mont Blanc), Stefan Simion (Université Paris-Saclay) for outstanding contributions to the ATLAS Liquid Argon Calorimeter Digital Trigger System.
Muhammad Alhroob (University of Oklahoma), Katarina Anthony (University of Udine), Steven Goldfarb (University of Melbourne), Clara Nellist (Radboud University), Elise Maria Le Boulicaut (Duke University), Sascha Mehlhase (Ludwig-Maximilians-Universität München) for outstanding contributions to the ATLAS outreach activities.
Bingxuan Liu (Simon Fraser University), Matthias Danninger (Simon Fraser University), John Stupak (University of Oklahoma), Robin Newhouse (University of British Columbia), Giuliano Gustavino (University of Oklahoma, CERN), Jackson Carl Burzynski (University of Massachusetts Amherst, Simon Fraser University) for outstanding contributions to the integration of large-radius tracking into the standard ATLAS reconstruction.
Artur Coimbra (CERN), Aimilianos Koulouris (National Technological University of Athens, University of Aegean, CERN), Luigi Longo (CERN, Università del Salento), Alexander Naip Tuna (CERN), Rimsky Alejandro Rojas Caballero (Federico Santa María Technical University, University of Victoria), Olga Zormpa (National Centre for Scientific Research “Demokritos”), Chiara Arcangeletti (University of Victoria), Rongkun Wang (Harvard University, University of Michigan and University of Science and Technology of China), Liang Guan (University of Michigan), Siyuan Sun (University of Michigan), Emanuele Romano (INFN Sezione di Pavia), Estel Perez Codina (TRIUMF), Alam Toro (TRIUMF), Gerardo Vasquez (University of Victoria), Camila Pazos (Brandeis University), Giada Mancini (National Laboratory of Frascati), Polyneikis Tzanis (National Technical University of Athens) for outstanding contributions to the completion of the NSW integration and surface commissioning within the LS2 schedule.

See the News Article on the 2022 Awards

2020 Outstanding Achievement Award Winners

The ATLAS Outstanding Achievement Award winners for 2020 are:

Laetitia Bardo (CERN), Marie-Solene Teurnier (CERN) and Laure Tranchand (CERN) for outstanding contributions and dedication to the safety of ATLAS, especially in 2020.
Susumu Oda (Kyushu University) for outstanding contributions to ATLAS software, notably the multithreaded migration of Athena.
Ewelina Maria Lobodinska (Deutsches Elektronen-Synchrotron DESY) for outstanding contributions to the development of Monte Carlo generator software in the Athena framework.
Clément Camincher (CERN), Adriana Milic (University of Toronto) and Nikiforos Nikiforou (University of Texas at Austin) for outstanding contributions to the operation and performance of the Liquid Argon Calorimeter.
Elodie Deborah Resseguie (University of Pennsylvania and Lawrence Berkeley National Laboratory), Shion Chen (University of Pennsylvania), George Ian Dyckes (University of Pennsylvania), Khilesh Pradip Mistry (University of Pennsylvania), Daniil Ponomarenko (National Research Nuclear University/MEPhI), Vincent Wong (University of British Columbia) and Keisuke Yoshihara (University of Pennsylvania) for outstanding contributions to the DAQ upgrades and commissioning directed to the TRT operation at high occupancy and trigger rates.
Toshi Sumida (Kyoto University), Tomomi Kawaguchi (Nagoya University), Junpei Maeda (Kobe University), Júlio Vieira de Souza (Universidade Federal de Juiz de Fora) for outstanding contributions to the reduction of the Level-1 muon endcap trigger rates.
Danijela Bogavac (IFAE) for outstanding contributions to the Tile Calorimeter maintenance and commissioning activities in LS2.
George Iakovidis (Brookhaven National Laboratory) for outstanding contributions to the development of front-end electronics and readout for the New Small Wheel detector.

See the News Article on the 2020 Awards

2018 Outstanding Achievement Award Winners

The ATLAS Outstanding Achievement Award winners for 2018 are:

Jeffrey R. Dandoy (University of Pennsylvania) and Khoo Teng Jian (University of Geneva) were celebrated for their creative and dedicated contributions to the measurement of jet energy and missing transverse momentum.
Alex Kastanas (Stockholm University) for his excellent contribution to the on-line luminosity software as well as dedicated operational support.
Noemi Calace (CERN) and Nora Emilia Pettersson (University of Massachusetts) for their remarkable contributions to the ITK upgrade project through simulation, reconstruction and performance studies.
Takuto Kunigo (Kyoto University), Tomoyuki Saito (ICEPP, University of Tokyo) and Shota Suzuki (KEK) were celebrated for their outstanding contributions in the development, deployment and commissioning of the trigger burst-stopper for the ATLAS Level-1 endcap muon system.
Olga Igonkina (Nikhef), Murrough Landon (Queen Mary University of London), Imma Riu (Barcelona Institute of Science and Technology), Eduard Simioni (University of Mainz) and Rosa Simoniello (University of Mainz) received awards for their exceptional contributions and dedication in successfully commissioning the Level-1 Topo trigger.
Ed Moyse (University of Massachusetts) and Scott Snyder (Brookhaven National Laboratory) for their outstanding contributions to software development and deployment.

See the News Article on the 2018 Awards.

2016 Outstanding Achievement Award Winners

The ATLAS Outstanding Achievement Award winners for 2016 are:

Marcello Bindi (University of Göttingen), Laura Jeanty (Berkeley National Lab), Kerstin Lantzsch (University of Bonn), Karolos Potamianos (Berkeley National Lab) and Yosuke Takubo (KEK) were celebrated for their outstanding contributions to the successful commissioning and operation of the Pixel Detector for the start-up of Run 2.
Dmitri Kharchenko (JINR), Uladzimir Kruchonak (JINR), Konstantin Levterov (JINR) and Enrico Pastori (University of Rome Tor Vergata and INFN) were celebrated for developing new techniques ensuring stable operation of the RPC gas system.
Filipe Martins (Laboratory of Instrumentation and Experimental Particle Physics (LIP)) for his contribution to the operations and upgrade of the TileCal Detector Control System.
Ricardo Abreu (University of Oregon), Patrick Czodrowski (CERN), Carlos Barajas (University of Sussex), Joana Machado Miguens (University of Pennsylvania) and Mark Stockton (McGill University) for their outstanding contributions to ensuring the integrity of the Trigger during Run 2.
The ATLAS Magnet Team, CERN VSC (Vacuum, Surfaces & Coatings) Team, CERN Central Workshop and CERN Detectors Technology Operations Group were celebrated for their outstanding work on the vacuum bellows for the Endcap C Toroid. This year, in addition to awarding specific members of the collaboration, special recognition was also given to these ATLAS and CERN groups.
Magda Chelstowska (CERN) and Christian Ohm (Berkeley National Lab) for providing prompt data reconstruction at Tier 0, especially during the 2015 run.
Attila Krasznahorkay (CERN) was given an award for his outstanding contributions to the development and implementation of the Run 2 analysis model, in particular the development of the xAOD.
Matthias Danninger (University of British Columbia) and Hideyuki Oide (University of Genoa and INFN) were celebrated for their outstanding contributions to the real-time tracking of the Insertable B-Layer alignment.

See the News Article on the 2016 Awards.

2015 Outstanding Achievement Award Winners

The ATLAS Outstanding Achievement Award winners for 2015 are:

Gabriel Facini (University of Chicago) and Anthony Morley (University of Sydney) were recognised for their outstanding contribution to improving track reconstruction in dense environments.
David Adams (Brookhaven National Laboratory) and Pierre-Antoine Delsart (CNRS) received awards for leading and implementing crucial changes to jet and Etmiss software and development of related xAOD dual use tools during LS1.
Tadashi Maeno (Brookhaven National Laboratory) was recognised for his contributions to the design, development and commissioning of innovative new distributed computing software critical to the LS1 S&C upgrade programme and the Run 2 physics programme, including JEDI and the Event Service.
James Frost (University of Oxford) was awarded for his contribution to the Data Preparation area, particularly for serving as PROC and DQ convener.
Ewa Stanecka (Polish Academy of Sciences) was awarded for her work in the Inner Detector DCS (Detector Control System).
Bruce M. Barnett (Rutherford Appleton Laboratory) was awarded for his contribution to the Level 1 calorimeter trigger over many years, and in particular in leading the system successfully through LS1.
Frederic Rosset and Cedric Sorde (both with CERN) were recognised for their contribution to the opening and closing process of the ATLAS experiment during LS1.
Koichi Nagai (University of Oxford) was recognised for his dedication to SCT operations and Run 2 commissioning.
Gary Drake (Argonne National Laboratory), Irakli Minashvili (JINR) and Stanislav Nemecek (Academy of Sciences of the Czech Republic) were awarded for their work leading to the improved reliability Low Voltage Power Supplies and the consolidation of the Front-End electronics of the Tile Hadronic Calorimeter for Run 2.
Jiri Masik (University of Manchester), Mark Sutton (University of Sussex), and Dmitry Emeliyanov and Stewart Martin-Haugh (both with STFC) were recognised for the drastic improvements in performance, timing and flexibility of the ATLAS Trigger Tracking software.
Moritz Backes and Michael Rammensee (both with CERN), Yu Nakahama (KEK), Catrin Bernius (New York University), and Tim Martin and Elisabetta Pianori (both with University of Warwick), received awards for their dedication to the implementation and commissioning of the complex ATLAS Run-2 trigger menu.
Guido Volpi (University of Pisa and INFN) was recognised for his original, crucial and extended work on designing the Fast Tracker system (FTK) and its simulation.
Nicholas Styles (DESY) received his award for his continuing work to establish and allow simulation and reconstruction of the Inner Detector for Phase II upgrade layouts.

See the News Article on the 2015 Awards.

2014 Outstanding Achievement Award Winners

The ATLAS Outstanding Achievement Award winners for 2014 are:

Martin Jäkel (CERN) was awarded for his contribution to the technical infrastructure and for being a pillar of the ATLAS operations for the whole of Run I.
Jörg Stelzer (CERN), Tomasz Bold (AGH University of Science and Technology Cracow), and Werner Wiedenmann (University of Wisconsin) - Chief architects of the Trigger Core Software group - were recognized for their work in the design, implementation, commissioning and support of the ATLAS Trigger Core Software.
John Chapman (University of Cambridge) was awarded for his work in ATLAS simulation, especially in developing, maintaining and coordinating the ATLAS pile-up simulation and digitisation. He dedicated the award to everyone who works in simulation in the collaboration.
Walter Lampl (University of Arizona), Stefan Simion (Laboratoire de l'Accelerateur Lineaire Orsay), and Denis Damazio (Brookhaven National Laboratory) were awarded for their work on the installation, maintenance and problem solving of the Liquid Argon front-end electronics and reconstruction, condition database, calibration, commissioning and running of the Liquid Argon detector during Run I.
Nikolay Azaryan, Vitaly Batusov, Mikhail Lyablin (Joint Institute for Nuclear Research Dubna), and Dirk Mergelkuhl (CERN) were recognised for their contribution in the alignment and survey work on almost all of the ATLAS detector components and supporting structures.

See the News Article on the 2014 Awards.

The status of a Technical Associate Institute is designed for research laboratories or universities that seek to have a close cooperation with the ATLAS Collaboration on primarily technical work for a dedicated project over an extended (multi-year) but limited period of time. They do not intend to join the ATLAS Collaboration as a full member Institution and do not intend to contribute to the ATLAS physics programme.

The principal reason for a Technical Associate membership is cooperation on one or more challenging technical project(s) relevant for the ATLAS Collaboration. These projects are possible in the areas of detector development, engineering, electronics, firmware, software and computing. They may be linked to detector upgrade programmes. Engagement in R&D activities that could potentially be of interest for ATLAS is possible as well. There should be clear benefit to the group joining, as well as to ATLAS, from the application.

Given that no full membership is anticipated, no financial contribution to enter the collaboration and no M&O costs have to be paid. Technical Associate Institutes are not required to contribute to the OT tasks; however, they are welcome to do so, concerning the maintenance and operation of their deliverables.

Technical Associate Institutes appear under a separate heading on the list of ATLAS Institutions. While members from the Technical Associated Institutes do not sign the physics publications of the ATLAS Collaboration, they sign all project-related technical papers where they are involved together with authors from the ATLAS Collaboration.

Initial contact should be with the ATLAS Spokesperson or with Project or Activity Leaders of Technical Projects in ATLAS.
The applicant group should prepare an Expression of Interest detailing the interest of the group in a specific project, its background and the involved personnel (scientist, engineers and students) as well as the timeline of the common project between the ATLAS Collaboration and the applicant group and, linked to this, the duration of the association.
The applicant group will be associated to one or more ATLAS detector systems and/or activity areas and well-defined deliverables should be defined. Long-term maintenance and OT linked to the deliverable of a Technical Associate Institute is the responsibility of the respective system or activity area. The Project Leaders and/or Activity Coordinators have to find appropriate groups (ATLAS Institutions) to cover this. Therefore, it is desirable that Technical Associate Institutes collaborate closely with existing ATLAS Institutions. It is also possible that the Technical Associate Institutes stay engaged beyond the development and construction phase and take longer-term commitments for operation.
Technical Associate Institutes might partake in the resources available for technical projects in ATLAS, e.g. for upgrade projects or for software and computing projects, from central ATLAS resources or from resources in the respective countries. In the latter case the agreement of the respective national ATLAS community and the funding agency is required and a supporting letter from the corresponding NCP is expected.
Before Technical Associate Institute status is granted, an agreement between the Technical Associate Institute and CERN (as the Host Laboratory) has to be prepared. Such an agreement should specify the details and deliverables of the project as well as ownership and definition of responsibilities for maintenance and operations. Where the technical project involves a contribution to an ATLAS Upgrade Project, the Technical Associate Institute has to comply with the agreed ATLAS procedures for preparation and implementation including critical reviews and timelines.
The agreement with CERN is presented by the Spokesperson to the ATLAS CB, and a formal vote on the admission is taken. After admission by the CB and after signature of the agreement the Technical Associate Institute status is granted. The admission of a new Technical Associate Institute does not require an endorsement by the RRB, as the CB composition is unchanged; however, the RRB would be notified.

The Associate Institute status is intended for universities or research labs that are on the path to joining ATLAS as a full institutional member.

The Associate Institute is hosted by a current ATLAS full-member Institution, which takes some responsibility for the associated group. Members of the Associate Institute will collaborate with the host Institution. There should be clear benefit shown to the Institution being joined, as well as to ATLAS, from the application.

Associate Institutes do not appear on the list of Institutions in the ATLAS author list. Scientific authors from Associate Institutes instead appear as authors of the host Institution, with an “Also at [Associate Institute]” footnote upon request. Associate Institutes are generally not a visible part of the ATLAS Collaboration. They do not appear in the CERN "Grey Book", nor do they have the right to open a Team Account at CERN based on their ATLAS Associate Institute status.

Initial contact should be made with the team leader of the Institution proposed, or directly with the ATLAS Spokesperson, who will put the group in touch with nearby member Institutions, if appropriate. In any case, informal contact should be made at an early stage with the Spokesperson and with the NCP of the nation concerned.
The applicant group should prepare a short statement of interest, including a description of the general structure (staff, students, engineers) and background of the group, expectations for its evolution, specific interests (projects, activity areas in ATLAS) and work programme. It is expected that members of the applicant institute will begin qualification to become ATLAS authors.
Statements of support will be required from the team leader of the Institution being joined and the NCP, who should also ensure that the funding agency concerned is in agreement.
With an Associate Institute joining, the institutional responsibilities (M&O and OT shares) are increased. These are assigned to the host Institution, which should agree with the Associate Institute how they will be met. Payment of the additional M&O contributions will start for the calendar year after admission.
The acceptance of an Associate Institute is at the discretion of the Spokesperson and Collaboration Board chair. The Collaboration Board shall be informed and comments solicited, before acceptance is implemented. The admission of a new Associate Institute does not require a CB vote or endorsement by the RRB, as the CB composition is unchanged.

Clustered Institutions (Clusters) are typically intended for institutes in nations where the High-Energy Physics community is still developing, and where it may be difficult to form individual university groups large enough to stand alone in ATLAS. It is expected that members of a Cluster (Cluster institutes) work closely together and build up a coherent effort in ATLAS.

Each Cluster will have one vote in the ATLAS Collaboration Board.

The requirements for a new Cluster to join ATLAS are the same as for single Institutions. The obligations on joining fees, M&O and OT contributions have to be fulfilled by the Cluster as a whole.

The requirements for a new institute joining a Cluster as an additional institute are less stringent. No entrance fee has to be paid, however the financial and effort obligations (M&O and OT contributions) of the Cluster increase according to the number of additional authors. The application should benefit the Cluster being joined, as well as the ATLAS Collaboration as a whole.

Clusters appear – and are marked as such – in the list of institutes in ATLAS publications. The individual Cluster institutes are listed consecutively.

Initial contact should be made with the leader of the Cluster team the new institute proposes to join, or directly with the ATLAS Spokesperson. In any case, informal contact should be made at an early stage with the Spokesperson and with the National Contact Physicist (NCP) of the nation concerned.
The applicant group should prepare a short statement of interest, including a description of the general structure (staff, students, engineers) and background of the group, expectations for its evolution, specific interests (projects, activity areas in ATLAS) and work programme. Connections and relations to other institutes in the Cluster they wish to join should be described. Members of the applicant institute are expected to begin qualification to become ATLAS authors.
Support will be required from the leader of the Cluster being joined and the NCP of the nation, who should also ensure that the funding agency concerned is in agreement.
The applicant institute, and the Cluster they propose to join, need to accept the financial and effort implications of joining, i.e. increased shares of M&O and OT contributions, commensurate with the number of additional authors, qualifiers and students (see above). Payment of the additional M&O contributions will start for the calendar year after admission. The leader of the Cluster is responsible for ensuring that these commitments will be met by the engaged institutes in the Cluster.
The addition of the institute to the Cluster is at the discretion of the Spokesperson and Collaboration Board chair. The Collaboration Board shall be informed and comments solicited, before the admission to the Cluster is completed. The admission of a new institute into a Cluster does not require a CB vote or endorsement by the RRB, as the CB composition is unchanged.

Full Institutional Members (Institutions) have full rights and obligations in the Collaboration. In particular, they are represented in the Collaboration Board (CB). This is an assembly of all ATLAS Institutions, where major decisions for the collaboration are discussed and voted on. Every Institution is equal, with one vote each.

ATLAS Institutions are expected to contribute to the Operation and Maintenance (M&O), to Operation Tasks (OT), and physics programme of the ATLAS experiment, as well as to the detector upgrade programme for operation at the High-Luminosity LHC. ATLAS Institutions have the following obligations:

To enter the ATLAS Collaboration as a full Institutional Member, a financial contribution must be paid. This contribution can, in part, be delivered “in-kind”, by providing well-defined deliverables in technical areas, e.g. software or firmware. Details are to be discussed with the Spokesperson.
There is a yearly share of M&O costs of around 10 kCHF per author (or qualifying author) holding a PhD or equivalent (M&O author). In addition, a common fund contribution of about 1.5 kCHF per M&O author, per year is paid during the High-Luminosity LHC detector upgrade phase (2018–2025). There are no M&O payments for students.
Institutions take on a share of the OT, such as shifts or data quality monitoring, and corresponding institutional commitments. For the OT requirements students are also included, however with a lower weight of 0.75. An increased OT share is expected to be taken by the joining groups during the first two years.
New groups are also expected to contribute to the Phase-II upgrade of the ATLAS experiment.
The admission of a new full member Institution is taken by a vote at the CB and endorsement by the Resources Review Board (RRB) need to be obtained.

A new group usually starts working with ATLAS before any formal engagement is taken. This happens most efficiently by being hosted by an existing ATLAS Institution, e.g. as an Associate Institute (see below). This initial work helps to establish and foster the mutual interest for future long-term Institutional Membership.
After about one year, the new group may submit an Expression of Interest (EoI) to join the ATLAS Collaboration, describing its general structure (staff, students, engineers), the expertise of the group, its planned activities and contributions to ATLAS as well as its projected evolution. At that stage the group must demonstrate a critical size, i.e. it should have permanent staff and typically more than one faculty member. The group must have a well-defined set of interests and a plan for long-term engagement within the collaboration.
The EoI is announced by the Spokesperson to the ATLAS CB, followed by a short presentation of the group leader of the applicant institute. Earliest one CB later (there are three per year) a formal vote on the admission can be taken. A statement of support is required from the National Contact Physicist of the respective nation, who should also ensure that both the ATLAS national community (if it exists already) and the funding agency/ies concerned are in agreement. In addition, a supporting statement from the Project Leader or Activity Coordinator of the areas where the new group plans to get engaged is required.

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Magnet System

Bends particles around the various layers of detector systems

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Identifies and measures the momenta of muons

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Measures the energy a particle loses as it passes through the detector

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