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Topic 1: "Fundamental Particles and Forces"

Infrastructures

The topic Fundamental Particles and Forces exploits accelerators, particle detectors at storage rings and huge computing infrastructures as well as laboratory and test-beam infrastructures. The major ones are:

 

  • LHC and the experiments ATLAS and CMS: The Large Hadron Collider at CERN is the world's largest particle accelerator and top priority in the worldwide elementary particle physics strategy. LHC started operation in 2008. Until the beginning of the Long Shutdown 1 in early 2013, the machine delivered close to 30 fb–1 of data to the general purpose experiments ATLAS and CMS, at centre-of-mass energies of 7 and 8 TeV. Yet the machine
    is still in its infancy. The current LHC planning foresees a restart of the physics programme at 13–14 TeV in early 2015 and the collection of about 350 fb–1 until the beginning of the Long Shutdown 3 that will equip the LHC for high-luminosity running (HL-LHC) with the goal of collecting 3000 fb–1.

 

  • SuperKEKB and Belle II: The KEK accelerator at the Japanese high energy physics laboratory KEK is currently being upgraded to SuperKEKB, a next-generation b-quark factory that starts up in 2015 and aims at achieving a luminosity of 8  1035 cm–2 s–1 and a data sample as large as 50 ab–1 in the rst half of the next decade. The Belle II experiment is designed to make use of high-precision measurements of phenomena like CP violation or of interference e ects in e+e collisions. The Belle II collaboration is formed by 94 institutions from 23 countries, comprising about 600 physicists.

 

  • GridKa at KIT: The German Tier-1 computing centre is hosted at KIT. As a Tier-1 centre, GridKa is mainly responsible for custodial storage of raw and processed data and centrally coordinated processing and re-processing campaigns. It constitutes an important node for data distribution and provides archival tape storage for raw and simulated data. GridKa primarily serves the LHC computing needs, which are most demanding, but also serves non-LHC experiments such as Belle II and others. On a worldwide scale the German share in Tier-1 computing slightly exceeds the fraction of German authors on LHC physics publications. This imbalance is well explained by the lack of Tier-1 installations in some collaborating countries.

 

  • Tier-2 centre and NAF at DESY: At its two locations in Hamburg and Zeuthen, DESY is operating a Tier-2 centre providing massive computing and storage facilities for the LHC experiments ATLAS, CMS and LHCb. Together with the National Analysis Facility (NAF), DESY's Tier-2 centre is one of the largest among the globally distributed centres of the "Worldwide LHC Computing Grid" (WLCG) and always counts among the top-performing centres for uptime and reliability.

 

  • Test-beam facility at DESY: DESY presently operates the DESY II synchrotron as pre-accelerator for the PETRA III facility. In parallel DESY II delivers electron or positron beams to three test-beam areas using a xed target with an energy variable between 1 and 6 GeV. Next to CERN — which has beam facilities for even higher energies and different particles (hadrons, muon and neutrinos) — DESY is currently the only laboratory in Europe which can deliver highly energetic particles in the multi-GeV range.

    The three test-beam areas provide sucient space for the installation of larger-scale detector prototypes. Two of the beam areas are equipped with high-resolution pixel beam telescopes to provide precise track information, an extremely useful tool for testing tracking detector prototypes. The third beam line provides a large-bore super-conducting magnet for prototype testing in magnetic elds of up to 1 T strength.

 

 

Future Infrastructures

In the topic Fundamental Particles and Forces, the planned infrastructures concentrate on the exploitation of the full potential of the LHC machine via upgraded detectors and massively extended computing facilities as outlined below. In addition, the ILC, as the next large facility for elementary particle physics, has a high priority:

 

  • ILC: The International Linear Collider — a linear e+e collider of up to 1 TeV centre-of-mass energy — is the next large international project in elementary particle physics, supported by German, European and international roadmaps. As a precision tool, the ILC is the ideal complement to the LHC; it will be able to measure, with the highest precision, the details of the new state discovered at 126 GeV and also of other signatures of New Physics yet to be discovered. The ILC, for the construction of which a site was selected in August 2013, will be based on SCRF technology developed at DESY, thus placing the laboratory in a very
    responsible position.

 

Future Infrastructures common to all three topics

Essential upgrades of some existing infrastructures are expected to take place in the forthcoming PoF period. Two of these planned infrastructures are of concern to all three topics of the programme Matter and the Universe:

 

  • LHC detector upgrades: The LHC physics programme is designed for a period of at least 20 years to fully exploit its scientific potential. The corresponding necessary luminosity evolution has been laid down and entails particle rates and occupancies that some of the LHC detector components will not be able to stand; in particular the currently installed ATLAS and CMS tracking detectors will have reached the end of their lifetimes by 2020. Fortunately, technological progress has indicated solutions that will be able to overcome this challenge. These cutting-edge technologies, that are still the subject of research, have to be verified in detector system installations to eventually be used in upgrades for the LHC detectors. Similarly, the longstanding systematic approach of exploring novel detectors for applications at a future e+e collider will greatly benefit from system-level installations.

    DESY, GSI and KIT have demonstrated in the past their ability to construct large detectors in-house, a capability that is indispensable for the LHC upgrades. These institutes are prepared to assume a leading role in the construction of major detector systems. Consequently, a proposal for investment funds of 28 million euros to be submitted in autumn 2014 has been prepared that will permit Helmholtz participation in the construction of new large detector components. The Helmholtz centres serve as integration centres for the German and international community.

    For DESY, the centrepiece of this proposal is the construction of silicon strip end-caps for ATLAS and CMS. DESY plans to serve as a detector integration hub in the consortium with German universities and other international partners. DESY will produce a large fraction of the required detector modules and the support structures. The necessary investment for this endeavour amounts to 20 million euros and is vital for the success of the future LHC programme at DESY and subject of the proposal to Helmholtz. DESY will contribute an additional 5.5 million euros from non-strategic funding for setting up the necessary laboratory infrastructure in the form of a Detector Assembly Facility in the coming years.

    KIT proposes to use its expertise in detector readout systems to become a key partner in the upgrade of the CMS silicon tracker readout system and to develop, prototype and produce a significant part of the new readout and track-finding system in close collaboration with international partners. For this purpose, funds amounting to 3.8 million euros have been requested.

    With the continuation of the ALICE program, GSI aims to stay in the worldwide leadership in the study of ultra-relativistic heavy ion collisions. Together with several German universities, GSI holds the responsibility for the ALICE Time Projection Chamber (TPC), and the High-Level Trigger (HLT). GSI will in a leading way participate in the upgrade of the TPC end-caps to GEM readout, thereby also establishing this technology within the Helmholtz Association. GSI will further play an important role in adapting the HLT to online calibration and tracking, with important implications for experiments at FAIR. Altogether, the GSI share in the LHC detector upgrade proposal is 4.2 million euros.

 

  • Tier-1 and Tier-2 Computing for the future LHC: The discovery of a comparatively light Higgs particle has brought a new challenge for LHC computing — physics analyses now demand that the sensitivity for decay leptons of quite low transverse momentum be fully preserved. Therefore, thresholds can no longer be increased in order to reduce the data volume. In addition, the luminosity of the LHC machine will be significantly increased after the the currently ongoing long shutdown LS1. The recorded data volumes will thus increase significantly. The experiments have already responded in refining their triggers and in balancing the loads. However, after the long shutdown LS1 the computing installations will have to be significantly augmented to match the challenge.

    Therefore, in addition to the LK II (performance category 2) proposal for the third funding period, DESY, GSI and KIT are preparing a large-investment proposal for a total funding of 33.1 million euros for a period of five years. It is planned to adapt both the Tier-1 and Tier-2 computing capabilities for all four LHC experiments to the increased needs. On the GridKa Tier-1 side, this requires increased storage and processing capabilities and adaptions to the evolved computing models of the LHC experiments as well as of the future Belle II experiment.

    On the Tier-2 side, funding would support both the Tier-2 centre at GSI (ALICE) and the Tier-2 centre and National Analysis Facility, NAF at DESY (ATLAS, CMS, LHCb); in addition, contributions to the maintenance of Tier-2 installations at universities that provide a significant portion of the current Tier-2 compute capability in Germany would be funded.