SNO+

Abstract:

The GridPP Collaboration is building a UK computing Grid for particle physics, as part of the international effort towards computing for the Large Hadron Collider. The project, funded by the UK Particle Physics and Astronomy Research Council (PPARC), began in September 2001 and completed its first phase 3 years later. GridPP is a collaboration of approximately 100 researchers in 19 UK university particle physics groups, the Council for the Central Laboratory of the Research Councils and CERN, reflecting the strategic importance of the project. In collaboration with other European and US efforts, the first phase of the project demonstrated the feasibility of developing, deploying and operating a Grid-based computing system to meet the UK needs of the Large Hadron Collider experiments. This note describes the work undertaken to achieve this goal. © 2006 IOP Publishing Ltd.

Abstract:

We present a study of the dijet invariant mass distribution for the reaction p̄p→twojets+γ+X, at a center of mass energy of 1.8 TeV, using data collected by the CDF experiment. We compare the data to predictions for the production of a photon with two jets, together with the resonant processes p̄p→W/Z+γ+X, in which the W and Z bosons decay hadronically. A fit is made to the dijet invariant mass distribution combining the nonresonant background and resonant processes. We use the result to establish a limit for the inclusive production cross section of W/Z+γ with hadronic decay of the W and Z bosons. © 2006 The American Physical Society.

Abstract:

We are developing a system of interferometers to measure relative motion between two objects (for example, the two final focus quadrupoles of a linear collider) to a few nanometers. Two instruments are under development in the John Adams Institute at the University of Oxford : A distance meter to measure length changes and a straightness monitor to measure perpendicular shifts. We will present the technique, results and resolutions of our distance meter prototype. We also examine the applications of interferometers at the ILC.

Abstract:

The simulations used in the field of high energy physics are compute intensive and exhibit a high level of data parallelism. These features make such simulations ideal candidates for Grid computing. We are taking as an example the GEANT4 detector simulation used for physics studies within the ATLAS experiment at CERN. One key issue in Grid computing is that of network and system security, which can potentially inhibit the wide spread use of such simulations. Virtualization provides a feasible solution because it allows the creation of virtual compute nodes in both local and remote compute clusters, thus providing an insulating layer which can play an important role in satisfying the security concerns of all parties involved. However, it has performance implications. This study provides quantitative estimates of the visualization and hyper-threading overhead for GEANT on commodity clusters. Results show that virtualization has less than 15% run-time overhead, and that the best run time (with the non-SMP licence of ESX VMware) is achieved by using one virtual machine per CPU. We also observe that hyper-threading does not provide an advantage in this application. Finally, the effect of virtualization on run-time, throughput, mean response time and utilization is estimated using simulations.