3,481 research outputs found
The StoreGate: a Data Model for the Atlas Software Architecture
The Atlas collaboration at CERN has adopted the Gaudi software architecture
which belongs to the blackboard family: data objects produced by knowledge
sources (e.g. reconstruction modules) are posted to a common in-memory data
base from where other modules can access them and produce new data objects. The
StoreGate has been designed, based on the Atlas requirements and the experience
of other HENP systems such as Babar, CDF, CLEO, D0 and LHCB, to identify in a
simple and efficient fashion (collections of) data objects based on their type
and/or the modules which posted them to the Transient Data Store (the
blackboard). The developer also has the freedom to use her preferred key class
to uniquely identify a data object according to any other criterion. Besides
this core functionality, the StoreGate provides the developers with a powerful
interface to handle in a coherent fashion persistable references, object
lifetimes, memory management and access control policy for the data objects in
the Store. It also provides a Handle/Proxy mechanism to define and hide the
cache fault mechanism: upon request, a missing Data Object can be transparently
created and added to the Transient Store presumably retrieving it from a
persistent data-base, or even reconstructing it on demand.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 4 pages, LaTeX, MOJT00
Multi-core job submission and grid resource scheduling for ATLAS AthenaMP
AthenaMP is the multi-core implementation of the ATLAS software framework and allows the efficient sharing of memory pages between multiple threads of execution. This has now been validated for production and delivers a significant reduction on the overall application memory footprint with negligible CPU overhead. Before AthenaMP can be routinely run on the LHC Computing Grid it must be determined how the computing resources available to ATLAS can best exploit the notable improvements delivered by switching to this multi-process model. A study into the effectiveness and scalability of AthenaMP in a production environment will be presented. Best practices for configuring the main LRMS implementations currently used by grid sites will be identified in the context of multi-core scheduling optimisation
Determination of the branching ratios and
Improved branching ratios were measured for the decay in a
neutral beam at the CERN SPS with the NA31 detector: and .
From the first number an upper limit for and transitions in neutral kaon decay is derived. Using older results for the
Ke3/K3 fraction, the 3 branching ratio is found to be , about a factor three more
precise than from previous experiments
A Development Environment for Visual Physics Analysis
The Visual Physics Analysis (VISPA) project integrates different aspects of
physics analyses into a graphical development environment. It addresses the
typical development cycle of (re-)designing, executing and verifying an
analysis. The project provides an extendable plug-in mechanism and includes
plug-ins for designing the analysis flow, for running the analysis on batch
systems, and for browsing the data content. The corresponding plug-ins are
based on an object-oriented toolkit for modular data analysis. We introduce the
main concepts of the project, describe the technical realization and
demonstrate the functionality in example applications
A new measurement of direct CP violation in two pion decays of the neutral kaon
The NA48 experiment at CERN has performed a new measurement of direct CP
violation, based on data taken in 1997 by simultaneously collecting K_L and K_S
decays into pi0pi0 and pi+pi-. The result for the CP violating parameter
Re(epsilon'/epsilon) is (18.5 +/- 4.5(stat)} +/- 5.8 (syst))x10^{-4}.Comment: 18 pages, 6 figure
Report of the AOD Format Task Force
The Analysis Object Data (AOD) are produced by ATLAS reconstruction and are the main input for most analyses. AOD, like the Event Summary Data (ESD, the other main output of reconstruction) are written as POOL files and are readable from Athena, and, to a limited extent, from ROOT. The AOD typical size, processing speed, and their relatively complex class structure and package dependencies, make them inconvenient to use for most interactive analysis. According to the computing model, interactive analysis will be based on Derived Physics Data (DPD), a user-defined format commonly produced from the AOD. As of release 12.0.3 it is common practice to write DPD as Athena-aware Ntuples (AANT) in ROOT. In an effort to organize and standardize AANT, we introduced the Structured Athena-aware Ntuple (SAN), an AANT containing objects that behave, as much as it is allowed by ROOT interpreter limitations, as their AOD counterparts. Recently it was proposed to extend SAN functionality beyond DPD implementation. SAN objects would be used as AOD objects. The TOB formed our task force with the mandate to "perform a technical evaluation of the two proposals, one based upon the existing AOD classes and architecture, the other upon Structured Athena-Aware Ntuples. [...] Criteria for the evaluation should include I/O performance, support for schema evolution, suitability for end user analysis and simplicity.
Search for Narrow Diphoton Resonances and for gamma-gamma+W/Z Signatures in p\bar p Collisions at sqrt(s)=1.8 TeV
We present results of searches for diphoton resonances produced both
inclusively and also in association with a vector boson (W or Z) using 100
pb^{-1} of p\bar p collisions using the CDF detector. We set upper limits on
the product of cross section times branching ratio for both p\bar
p\to\gamma\gamma + X and p\bar p\to\gamma\gamma + W/Z. Comparing the inclusive
production to the expectations from heavy sgoldstinos we derive limits on the
supersymmetry-breaking scale sqrt{F} in the TeV range, depending on the
sgoldstino mass and the choice of other parameters. Also, using a NLO
prediction for the associated production of a Higgs boson with a W or Z boson,
we set an upper limit on the branching ratio for H\to\gamma\gamma. Finally, we
set a lower limit on the mass of a `bosophilic' Higgs boson (e.g. one which
couples only to \gamma, W, and Z$ bosons with standard model couplings) of 82
GeV/c^2 at 95% confidence level.Comment: 30 pages, 11 figure
Measurement of J/Psi and Psi(2S) Polarization in ppbar Collisions at sqrt(s) = 1.8 TeV
We have measured the polarization of J/Psi and Psi(2S) mesons produced in
p\bar{p} collisions at \sqrt{s} = 1.8 TeV, using data collected at CDF during
1992-95.
The polarization of promptly produced J/Psi [Psi(2S)] mesons is isolated from
those produced in B-hadron decay, and measured over the kinematic range 4[5.5]
< P_T < 20 GeV/c and |y| < 0.6. For P_T \gessim 12 GeV/c we do not observe
significant polarization in the prompt component.Comment: Revised version, accepted for publication in Physical Review Letter
Measurement of Rapidity Distribution for High Mass Drell-Yan ee Pairs at CDF
We report on the first measurement of the rapidity distribution dsigma/dy
over nearly the entire kinematic region of rapidity for e^+e^- pairs in the
Z-boson region of 66116 GeV/c^2.
The data sample consists of 108 pb^{-1} of ppbar collisions at \sqrt{s}=1.8 TeV
taken by the Collider Detector at Fermilab during 1992--1995. The total cross
section in the -boson region is measured to be 252 +- 11 pb. The measured
total cross section and d\sigma/dy are compared with quantum chromodynamics
calculations in leading and higher orders.Comment: 7 pages, 3 figures. Submitted to Physical Review Letter
Measurement of the Decay Amplitudes of B0 --> J/psi K* and B0s --> J/psi phi Decays
A full angular analysis has been performed for the pseudo-scalar to
vector-vector decays, B0 --> J/psi K* and B_s --> J/psi phi, to determine the
amplitudes for decays with parity-even longitudinal and transverse polarization
and parity-odd transverse polarization. The measurements are based on 190 B0
candidates and 40 B_s candidates collected from a data set corresponding to 89
inverse pb of pbarp collisions at root(s) = 1.8 TeV at the Fermilab Tevatron.
In both decays the decay amplitude for longitudinal polarization dominates and
the parity-odd amplitude is found to be small.Comment: 7 pages, 3 figures, 1 tabl
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