In the last 15 years it has become clear that something is missing in the Big Bang theory. The Universe is

expanding and cooling down. But there is a problem with the black holes. There is additional matter out there which we do not understand. More than 95% of unknown stuff, noted Ian Bird, which brings us to the following fundamental physics questions:

• Why do particles have mass? Newton could not explain it.
• What is 96% of the universe made of?
• Why is there no antimatter left in the universe?
• What was matter like during the first second of the universe right after the Big Bang?

CERN stands for over 50 years of fundamental research and discoveries, technological innovation, training and education, and bringing the world together to try and answer these questions. CERN has a staff of 2328 people with 711 fellows and associates, and 9535 users.

CERN deploys the world's most powerful accelerator, the Large Hydron Collider which is a 27 km long tunnel filled with high-tech instruments, equipped with thousands of superconducting magnets. The LHC accelerates particles to energies never before obtained and produces particles collisions creating microscopic big bangs, explained Ian Bird.

The tunnel consists of very large sophisticated detectors. Up to now there have been 4 experiments and two of them were general purpose experiments. Alice is a very specific detector and the ATLAS detector weighs 7000 tons and includes 150 million sensors.

The LHC accelerates protons in opposite directions. The energy stored in a magnet is sufficient to heat up and melt 15 tons of copper. The energy stored in one LHC beam corresponds approximately to 90 ton of TNT, just to give an idea. There are 1 billion proton collisions in the detector per second.

Ian Bird told the audience that the HEP data are organized as events - particle collisions. The Simulation, Reconstruction and Analysis programmes process "one Event at a time". Events are fairly independent.

The MonteCarlo simulation follows the evolution of physics processes from collision to digital signals. The

reconstruction goes back in time from digital signals to the original particles produced in the collision, noted Ian Bird.

LHC Computing Challenge is enormous giving the fact that the signal/noise is 10 to the 13th. The data volume amounts to 15 petabytes of new data each year. The compute power is of the order of 100 k of the fastest CPUs and we are talking 45 PB of disk storage. There is a worldwide analysis and funding going on with computing funding locally in major regions and countries. To enable an efficient analysis everywhere, there is an urgent need for Grid technology.

The data handling and computation for physics analysis develops as follows: there is an event filter, an event summary, a batch physics analysis, an event simulation, and finally an event reprocessing.

The LHC computing hierarchy is born out of an emerging vision of a richly structured, global dynamic system which will have tens of petabytes by 2010, explained Ian Bird. It consists of the following levels: Tier 1 - Tier 0 + 1 - Tier 2 - Tier 3.

The Tier 0 is situated at CERN and deals with acquisition, first pass processing, storage and distribution. The

responsibilities at each Tier are very specific. There are two copies of the raw data. They are distributed by Tier 1 which is also responsible for permanent storage. Tier 2 is dealing with the simulation role and end-user analysis.

The WLCG is a distributed computing infrastructure to provide the production and analysis environments for the LHC experiments. It has been set up in two phases:

1. development and planning; prototypes

2. 2006-2008: deployment and commissioning of the initial services programme of data and service challenges

During phase 2 the WLCG collaboration was set up as the mechanism for the longer term via a Memorandum of Understanding (MoU). There are 49 MoU signatories, representing 34 countries, explained Ian Bird.

Since 2004 WLCG has been running a series of challenges to demonstrate aspects of the system; with increasing targets for data throughput; workloads; service availability and reliability.

The recent challenges are significant. As far as the data transfer is concerned, the full experiment rate needed is 650 MB/s. There is a desired capability to sustain twice that to allow for Tier 1 sites to shut down and recover.

Experiments have demonstrated far in excess of that. All experiments exceeded required rates for extended periods, and simultaneously. All Tier 1s have exceeded their expectations, announced Ian Bird.

The Grid activity is the distribution of CPU delivered. The distribution of work across Tier0/Tier1/Tier 2 really illustrates the importance of the Grid system: the Tier 2 contribution is about 50%. Ian Bird told that 85% is external to CERN.

In September 2008 the first events occurred.

WCLG depends on two major science Grid infrastructures: EGEE and the Open Science Grid (OSG). Their interoperability and interoperation is vital. A significant effort has been put in building the procedures to support it.

The impact of the LHC computing Grid in Europe has been enormous. LCG has been the driving force for the European multi-science community. The flagship Grid infrastructure project is being co-funded by the European Commission.

EGEE achievements and applications consist of more than 270 Virtual Organisations from several scientific domains. Further applications are under evaluation, noted Ian Bird.

At the EGEE scale we talk about 17.000 users, 136.000 LCPUs, 25 Pb of disk, 39 Pb of tape, 12 million jobs/month, 288 sites and 48 countries.

The EGEE Production infrastructure consists of support structures and processes; an operations co-ordination centre, regional operations centres; a global Grid user support, the EGEE network operations centre, an operational security co-ordination team, and training activities. Furthermore there are security and policy groups, and testbeds and services. The Middleware is gLite. Membership services are one of the key services.

Ian Bird told the audience that there are Grids, Clouds and supercomputers. Grids constitute a collaborative environment with distributed resources, commodity hardware, HEP data management, and complex interfaces.

Supercomputers are expensive, have low latency interconnects, are applications peer reviewed, run parallel/coupled applications, and have traditional interfaces.

Clouds are proprietary with an economies of scale in management.

So what is a Grid? asked Ian Bird. It is a collaborative environment, crossing many administrative boundaries. It is not subject to central control and is used by Virtual Organisations: thematic groups crossing administrative and geographical boundaries. Collaborations have been created that did not exist before.

In the future large Grid sites will be run as "Clouds" using virtualisation to provision services. Commercial Cloud offerings can be integrated for several - but not all - types of work such as simulations or compute-bound applications. The collaborative features of Grids are important.

We are starting to see multi-disciplinary and complex work flows. Today's middleware is complex with a large support effort. Grids are starting to use "standard" software.

For the sustainability, we need to prepare a permanent, common Grid infrastructure to ensure the long-term sustainability. So there is a high need for EGI, warned Ian Bird. The resources and funding have to be provided by EGEE and similar European Grid infrastructure projects.

The future European e-Infrastructure should encompass all types of resources allowing science to simply utilise those appropriate for the task at hand.

Simplification and evolution of Grid services themselves are necesarry, predicted Ian Bird. Grid can utilise commercial Cloud providers for certain applications. Virtualisation will be a mechanism to improve the provision of Grid services and to simplify application environments.

Grids have been extremely successful for HEP and WLCG in particular, concluded Ian Bird.