LHCLarge Hadron Collider (LHC) detector upgrades

Contact details:

prof S.C.M. Bentvelsen
Nikhef Science Park 105 1098 XG Amsterdam

The LHC is the world’s most powerful particle accelerator. The LHC experiments have in an early stage already discovered the Higgs particle and are expected to further clarify some of mankind’s most intriguing mysteries: • What is the particle content of our Universe? • How does it work? Anticipated breakthroughs are: elementary-particle masses (Higgs physics), matter-antimatter asymmetry (CP-violation), the search for Dark Matter (supersymmetry) and Quark-Gluon plasma. This progress report updates the Nikhef activities on the LHC-detector upgrades including the Dutch grid-compute centre NL/Tier-1 that secure the present excellent position of Dutch physicists to exploit the full LHC discovery potential during the next decade.

After a shutdown period of two years, LHC has begun a new running phase in 2015 at the highest attainable energy. This phase will last until 2018, with planned accumulated luminosity of LHC equals approximately 120 fb-1 (a measure of the total number of collisions). As part of this roadmap, during the shutdown in 2018-2020 (phase-1) parts of the ATLAS, LHCb and ALICE detectors will be expanded or replaced for optimal exploitation and discovery potential. During a following running phase the total accumulated luminosity is foreseen to increase to 300 fb-1 in 2023. At that moment the shutdown phase-2 will start in which the ATLAS detector undergoes a major upgrade to prepare for the High Luminosity LHC (HL-LHC) beyond 2024. Also the Dutch involvement in this upgrade is part of this roadmap project. LHC itself will also need a major upgrade to accommodate the increase of its luminosity by a factor of 10 beyond the original design value (from 300 to 3000 fb-1).
The responsibilities taken by Nikhef in view of this roadmap are summarised as
ATLAS (phase-1):
- Implementation of the readout of the new New Small Wheels (NSW) detectors as part of the Muon Spectrometer. The NSW enlarges the coverage of the muon spectrometer yielding a better efficiency for observation of e.g. the Higgs particle. The project includes the production of magnetic field and temperature sensors.
- Development and implementation of new trigger elements to optimise the selection of events, notably using the calorimeter information in combination with the muon spectrometer.
ATLAS (phase-2):
- ATLAS will replace the complete Inner Tracker as the collision rates are to high at HL-LHC for the current tracker. Nikhef will assemble one of the endcaps for this Inner Tracker.
- This project comes with the development of Strip- and Pixel sensors with corresponding petal support structures for the endcap. All underlying services (cooling, high- and low-power cabling, data transport etc) as well.
LHCb (phase-1):
- The vertex detector is a newly built silicon pixel detector measuring the collisions at the LHC interaction point. The Dutch contribution includes the construction of the vacuum encapsulation of the detector, the production of half of the silicon detector modules, and contributions to the VeloPix ASIC design.
- The magnet tracker is a novel large surface scintillating fibre tracker measuring particle tracks in the large LHCb dipole magnet field. The contribution includes the design and construction of part of the 3 meter long detector modules. The design focuses on the cold-box housing Silicon Photomultiplier detectors. In addition we contribute to the development of Front-End electronics boards and to the overall infrastructure (frames etc) of the detector.
- Finally the contribution to the High Level Trigger includes as a common contribution of all institutes to the purchase of the computing farm.

ALICE (phase-1):
- The ALICE Collaboration has proposed an Upgrade program of the ALICE Detector consisting of modification and replacement of existing sub-detectors as well as new additions to the detector. Nikhef contributes to the Inner Tracking System (ITS) electronics and assembly.
Computing (ATLAS, LHCb, ALICE):
- Provision of roughly 10% of the global Tier-1 computing needs (each experiment has about ten Tier-1s scattered around the globe) of the three experiments. This requires and relies on the expertise of Nikhef and partners in the Dutch National eInfrastructure concerning large-scale high-performance computing, storage, and advanced networking. R&D work to follow the increasing capacity requirements are funded partly by the Dutch National eInfrastructure. Nikhef also has assumed substantial responsibility for the LHCb trigger algorithms, which must be speeded up by factors in order to deal with the data rates encountered in phase-2. This responsibility is not part of the current proposal but is very closely related.
The research of LHC fits perfectly well in the Nationale Wetenschaps Agenda route “Bouwstenen van materie en fundamenten van ruimte en tijd” with corresponding questions NW128 “Kennen we alle elementaire bouwstenen van materie?” and NW130 “Wat is donkere materie en wat is donkere energie?”. The data-intensive, high throughput computing infrastructure fits very well in the Big Data route of the NWA.

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