Dirk Duellmann

CERN | CERN · Information Technology Department (IT)

Today, cloud systems provide many key services to development and production environments; reliable storage services are crucial for a multitude of applications ranging from commercial manufacturing, distribution and sales up to scientific research, which is often at the forefront of computing resource demands. In large-scale computer centers, the...

The increase in the scale of LHC computing during Run 3 and Run 4 (HL-LHC) will certainly require radical changes to the computing models and the data processing of the LHC experiments. The working group established by WLCG and the HEP Software Foundation to investigate all aspects of the cost of computing and how to optimise them has continued pro...

In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km...

In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km...

In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km...

We review the physics opportunities of the Future Circular Collider, covering its e+e-, pp, ep and heavy ion programmes. We describe the measurement capabilities of each FCC component, addressing the study of electroweak, Higgs and strong interactions, the top quark and flavour, as well as phenomena beyond the Standard Model. We highlight the syner...

In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in...

In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in...

We review the physics opportunities of the Future Circular Collider, covering its e+e-, pp, ep and heavy ion programmes. We describe the measurement capabilities of each FCC component, addressing the study of electroweak, Higgs and strong interactions, the top quark and flavour, as well as phenomena beyond the Standard Model. We highlight the syner...

Particle physics has an ambitious and broad experimental programme for the coming decades. This programme requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment in the R&D of software to acquire, manage, process, and analyse the she...

In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km...

In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km...

In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCCee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in...

We review the physics opportunities of the Future Circular Collider, covering its e+e−, pp, ep and heavy ion programmes.We describe the measurement capabilities of each FCC component, addressing the study of electroweak, Higgs and strong interactions, the top quark and flavour, as well as phenomena beyond the Standard Model. We highlight the synerg...

The increase in the scale of LHC computing expected for Run 3 and even more so for Run 4 (HL-LHC) over the next ten years will certainly require radical changes to the computing models and the data processing of the LHC experiments. Translating the requirements of the physics programmes into computing resource needs is a complicated process and sub...

The EOS deployment at CERN is a core service used for both scientific data processing, analysis and as back-end for general end-user storage (eg home directories/CERNBOX). The collected disk failure metrics over a period of 1 year from a deployment size of some 70k disks allows a first systematic analysis of the behaviour of different hard disk typ...

Without significant changes to data organization, management, and access (DOMA), HEP experiments will find scientific output limited by how fast data can be accessed and digested by computational resources. In this white paper we discuss challenges in DOMA that HEP experiments, such as the HL-LHC, will face as well as potential ways to address them...

The statistical analysis of infrastructure metrics comes with several specific challenges, including the fairly large volume of unstructured metrics from a large set of independent data sources. Hadoop and Spark provide an ideal environment in particular for the first steps of skimming rapidly through hundreds of TB of low relevance data to find an...

CERN has been developing and operating EOS as a disk storage solution successfully for over 6 years. The CERN deployment provides 135 PB and stores 1.2 billion replicas distributed over two computer centres. Deployment includes four LHC instances, a shared instance for smaller experiments and since last year an instance for individual user data as...

The IT Analysis Working Group (AWG) has been formed at CERN across individual computing units and the experiments to attempt a cross cutting analysis of computing infrastructure and application metrics. In this presentation we will describe the first results obtained using medium/long term data (1 months — 1 year) correlating box level metrics, job...

Amazon S3 is a widely adopted web API for scalable cloud storage that could also fulfill storage requirements of the high-energy physics community. CERN has been evaluating this option using some key HEP applications such as ROOT and the CernVM filesystem (CvmFS) with S3 back-ends. In this contribution we present an evaluation of two versions of th...

Optimizing a computing infrastructure on the scale of LHC requires a quantitative understanding of a complex network of many different resources and services. For this purpose the CERN IT department and the LHC experiments are collecting a large multitude of logs and performance probes, which are already successfully used for short-term analysis (e...

Archiving data to tape is a critical operation for any storage system, especially for the EOS system at CERN which holds production data for all major LHC experiments. Each collaboration has an allocated quota it can use at any given time therefore, a mechanism for archiving "stale" data is needed so that storage space is reclaimed for online analy...

EOS is an open source distributed filesystem developed and used mainly at CERN. It provides low latency, high availability, strong authentication, multiple replication schemas as well as multiple access protocols and features. Deployment and operations remain simple and EOS is currently being used by multiple experiments at CERN providing a total r...

Cloud storage is an emerging architecture aiming to provide increased scalability and access performance, compared to more traditional solutions. CERN is evaluating this promise using Huawei UDS and OpenStack SWIFT storage deployments, focusing on the needs of high-energy physics. Both deployed setups implement S3, one of the protocols that are eme...

The International Conference on Computing in High Energy and Nuclear Physics (CHEP) was held at New York University on 21– 25 May 2012. CHEP is a major series of international conferences for physicists and computing professionals from the High Energy and Nuclear Physics community and related scientific and technical fields. The CHEP conference pro...

The Data and Storage Services group at CERN is conducting several service and software development projects to address possible scalability issues, to prepare the integration of upcoming technologies and to anticipate changing access patterns. Particular emphasis is put on: very high performance disk pools for analysis based on XROOTD [1] lower lat...

The CERN facility hosts the Tier-0 of the four LHC experiments, but as part of WLCG it also offers a platform for production activities and user analysis. The CERN CASTOR storage technology has been extensively tested and utilized for LHC data recording and exporting to external sites according to experiments computing model. On the other hand, to...

The use of proxy caches has been extensively studied in the HEP environment for efficient access of database data and showed significant performance with only very moderate operational effort at higher grid tiers (T2, T3). In this contribution we propose to apply the same concept to the area of file access and analyse the possible performance gains...

With the start of Large Hadron Collider approaching, storage and management of raw event data, as well as reconstruction and analysis data, is of crucial importance for the researchers. The CERN Advanced STORage system (CASTOR) is a hierarchical system developed at CERN, used to store physics production files and user files. CASTOR, as one of the e...

The CORAL package is the LCG Persistency Framework foundation for accessing relational databases. From the start CORAL has been designed to facilitate the deployment of the LHC experiment database applications in a distributed computing environment. In particular we cover - improvements to database service scalability by client connection managemen...

Database replication is a key topic in the framework of the LHC Computing Grid to allow processing of data in a distributed environment. In particular, the LHCb computing model relies on the LHC File Catalog, i.e. a database which stores information about files spread across the GRID, their logical names and the physical locations of all the replic...

The COmmon Relational Abstraction Layer (CORAL)1 is a C++ software system, developed within the context of the LCG persistency framework, which provides vendor-neutral software access to relational databases with defined semantics. The SQL-free public interfaces ensure the encapsulation of all the differences that one may find among the various RDB...

The pool of persistent objects for LHC (POOL) project, part of the large Hadron collider (LHC) computing grid (LCG), is now entering its third year of active development. POOL provides the baseline persistency framework for three LHC experiments. It is based on a strict component model, insulating experiment software from a variety of storage techn...

The POOL project, as a part of the LHC Computing Grid (LCG), is now entering its third year of active development POOL provides the baseline persistency framework for three LHC experiment and is based on a strict component model, insulating experiment software from a variety of storage technology choices. This paper gives a brief overview of the PO...

The POOL project has been created to implement a common persistency framework for the LHC Computing Grid (LCG) application area. POOL is tasked to store experiment data and meta data in the multi Petabyte area in a distributed and grid enabled way. First production use of new framework is expected for summer 2003. The project follows a hybrid appro...

The POOL data storage mechanism is intended to satisfy the needs of the LHC experiments to store and analyze the data from the detector response of particle collisions at the LHC proton-proton collider. Both the data rate and the data volumes will largely differ from the past experience. The POOL data storage mechanism is intended to be able to cop...

Data grids are currently proposed solutions to large-scale data management problems, including efficient file transfer and replication. Large amounts of data and the world-wide distribution of data stores contribute to the complexity of the data management challenge. Recent architecture proposals and prototypes deal with replication of read-only fi...

We present an initial study of the object features of Oracle 9i - the first of the market-leading object-relational database systems that supports a true object model on the server side as well as an ODMG-style C++ language binding on the client side. We discuss how these features can be used to provide persistent object storage in the HEP environm...

Bitmap indices are popular multi-dimensional data structures for accessing read-mostly data such as data warehouse (DW) applications, decision support systems (DSS) and on-line analytical processing (OLAP). One of their main strengths is that they provide good performance characteristics for complex adhoc queries and an efficient combination of mul...

This article describes the status of the ALPHA^{++} project of the ALEPH collaboration. The ALEPH data have been converted from Fortran data structures (BOS banks) into C^{++} objects and stored in a object oriented database (Objectivity/DB), using tools provided by the RD45 collaboration and the LHC^{++} software project at CERN. A description of...

This paper describes the use of Object-Database Management Systems (ODBMS) for the storage of High-Energy Physics (HEP) data.

This paper describes the use of Object-Database Management Systems (ODBMS) for the storage of High-Energy Physics (HEP) data.

Technical aspects of the three major components of the H1 detector at the electron-proton storage ring HERA are described. This paper covers the detector status up to the end of 1994 when a major upgrading of some of its elements was undertaken. A description of the other elements of the detector and some performance figures from luminosity runs at...

Results on J/ψ production in ep interactions in the H1 experiment at HERA are presented. The J/ψ mesons are produced by almost real photons (Q2 ≈ 0) and detected via their leptonic decays. The data have been taken in 1994 and correspond to an integrated luminosity of 2.7 pb-1. The γp cross section for elastic J/ψ production is observed to increase...

Data from electron-proton collisions at a center-of-mass energy of 300 GeV are used for a search for selectrons and squarks within the framework of the minimal supersymmetric model. The decays of selectrons and squarks into the lightest supersymmetric particle lead to final states with an electron and hadrons accompanied by large missing energy and...

A search for squarks ofR-parity violating supersymmetry is performed inep collisions at HERA using H1 1994e + data. Direct single production of squarks of each generation bye +-quark fusion via a Yukawa coupling λ′ is considered. All possibleR-parity violating decays and gauge decays of the squarks are taken into account. No significant deviation f...

A search for squarks of $R$-parity violating supersymmetry is performed in $ep$ collisions at HERA using H1 1994 $e^+$ data. Direct single production of squarks of each generation by $e^+$-quark fusion via a Yukawa coupling $\lambda'$ is considered. All possible $R$-parity violating decays and gauge decays of the squarks are taken into account. No...

The total cross sections for the elastic electroproduction of ρ and J/ψ mesons for Q2 > 8 GeV2 and (W) ≃ 90 GeV/c2 are measured at HERA with the H1 detector. The measurements are for an integrated electron - proton luminosity of ≃ 3 pb-1. The dependences of the total virtual photon - proton (γ*p) cross sections on Q2, W and the momentum transfer sq...

The total cross sections for the elastic electroproduction of rho and J/psi mesons for Q(2) > 8 GeV2 and [W] similar or equal to 90 GeV/c(2) are measured at HERA with the H1 detector. The measurements are for an integrated electron-proton luminosity of similar or equal to 3 pb(-1). The dependences of the total virtual photon-proton (gamma*p) cross...

An investigation of the hadronic final state in diffractive and non-diffractive deep-inelastic electron-proton scattering at HERA is presented, where diffractive data are selected experimentally by demanding a large gap in pseudo-rapidity around the proton remnant direction. The transverse energy flow in the hadronic final state is evaluated using...

The Q2 dependence and the total cross sections for charged and neutral current processes are measured in e±p reactions for transverse momenta of the outgoing lepton larger than 25 GeV. Comparable size of cross sections for the neutral current process and for the weak charged current process are observed above Q2 ∥ 5000 GeV2. Using the shape and mag...

A new measurement of the proton structure function F2 (x, Q2) is reported for momentum transfers squared Q2 between ].5 GeV2 and 5000 GeV2 and for Bjorken x between 3 · 10−5 and 0.32 using data collected by the HERA experiment H1 in 1994. The data represent an increase in statistics by a factor of ten with respect to the analysis of the 1993 data....

The cross section for the elastic photoproduction of rho(0) mesons (gamma p --> rho(0)p) has been measured with the H1 detector at HERA for two average photon-proton centre-of-mass energies of 55 and 187 GeV. The lower energy point was measured by observing directly the rho(0) decay giving a cross section of 9.1 +/- 0.9 (stat.) +/- 2.5 (syst.) mu b...

A search for leptoquarks at HERA was performed in H1 using 1994 e+p data corresponding to an integrated luminosity of about 3 pb−1. Single leptoquarks were searched for in direct positron-quark fusion processes taking into account possible decays into lepton-quark pairs of either the first, the second, or the third generation. No significant deviat...

At the electron-proton collider HERA the inclusive D*+/- meson photoproduction cross section has been measured with the H1 detector in two different, but partly overlapping, kinematical regions. For the first, where ≈ 200 GeV and Q2 < 0.01 GeV2, the result is σ (γp ->ccX ) = (13.2 +/- 2.2+2.1 + 9.9-1.7 -4.8) μb. The second measurement for Q2 < 4 Ge...

Properties of the hadronic final state in photoproduction events with large transverse energy are studied at the electron-proton collider HERA. Distributions of the transverse energy, jets and underlying event energy are compared to[`(p)]p\bar pp data and QCD calculations. The comparisons show that theγp events can be consistently described by QCD...

A search for leptoquarks at HERA was performed in H1 using 1994 e+p data corresponding to an integrated luminosity of about 3 pb−1. Single leptoquarks were searched for in direct positron-quark fusion processes taking into account possible decays into lepton-quark pairs of either the first, the second, or the third generation. No significant deviat...

The Q 2 dependence and the total cross sections for charged and neutral current processes are measured in e ± p reactions for transverse momenta of the outgoing lepton larger than 25 GeV. Comparable size of cross sections for the neutral current process and for the weak charged current process are observed above Q 2 ≈ 5000 GeV 2. Using the shape an...

At the electron-proton collider HERA the inclusive D∗± meson photoproduction cross section has been measured with the H1 detector in two different, but partly overlapping, kinematical regions. For the first, where 〈Wγp〉 ≈ 200 GeV and Q2 < 0.01 GeV2, the result is σ(γp → ccX) = (13.2 ± 2.2−1.7 −4.8+2.1 +9.9) μb. The second measurement for Q2 < 4 GeV...

Data from electron–proton collisions at a center-of-mass energy of 300 GeV are used for a search for selectrons and squarks within the framework of the minimal super-symmetric model. The decays of selectrons and squarks into the lightest supersym-metric particle lead to final states with an electron and hadrons accompanied by large missing energy a...

We present a new measurement of the total photoproduction cross section performed with the H1 detector at HERA. For an average centre of mass energy of 200 GeV a value of σ tot λp =165±2±11µb has been obtained. A detailed analysis of the data in adequate kinematic regions enabled a decomposition of the total cross section in its elastic, single dif...

The cross sections for the charged current processes {ie566-1} and, for the first time, {ie566-2} are measured at HERA for transverse momenta larger than 25 GeV.

We present a new measurement of the total photoproduction cross section performed with the H1 detector at HERA. For an average centre of mass energy of 200 GeV a value of sigma(tot)(gamma p) - 165 +/- 2 +/- 11 mu b has been obtained. A detailed analysis of the data in adequate kinematic regions enabled a decomposition of the total cross section in...

Photon-proton (γp) interactions with < 10−2 GeV2 and deep-inelastic scattering (γ∗p) interactions with photon virtualities > 5 GeV2 are studied at the high energy electron-proton collider HERA. The transverse energy flow and relative rates of large rapidity gap events are compared in the two event samples. The observed similarity between γp and γ∗p...

We present a QCD analysis of the proton structure function F-2 measured by the H1 experiment at HERA, combined with data from previous fixed target experiments. The gluon density is extracted from the scaling violations of F-2 in the range 2.10(-4) < x < 3.10(-2) and compared with an approximate solution of the QCD evolution equations. The gluon de...

A leading order determination of the gluon density in the proton has been performed in the fractional momentum range 1.9 · 10−3 < xg/p < 0.18 by measuring multi-jet events from boson-gluon fusion in deep-inelastic scattering with the H1 detector at the electron-proton collider HERA. This direct determination of the gluon density was performed in a...