Rubin-LSST

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.

Abstract:

A prototype TPC has been completed and commissioned at Cornell for the purpose of evaluating performance and reliability of candidate gas-amplification devices and pad configurations. The TPC has an active area of 10cm square and a drift length of 64cm. The current readout electronics includes 32 channels of 14 bit, 105 MHz 14flash-ADCs. Baseline measurements have been taken with a wire gas-amplification module. The Purdue group has prepared a single GEM readout module. First results using the wire gas-amplification and single GEM are described.

Abstract:

We report on a search for Bs0â†Î+Î- and Bd0â†Î+Î- decays in ppÂcollisions at s=1.96TeV using 364â€â€pb-1 of data collected by the CDF II detector at the Fermilab Tevatron Collider. After applying all selection requirements, we observe no candidates inside the Bs0 or Bd0 mass windows. The resulting upper limits on the branching fractions are B(Bs0↠Î+Î-)<1.5Ã-10-7 and B(Bd0â†Î+Î-) <3.9Ã-10-8 at 90% confidence level. © 2005 The American Physical Society.