Interactive 3D data visualization plays a key role in HEP experiments, as it is used in many tasks at different levels of the data chain. Outside HEP, for interactive 3D graphics, the game industry ...makes heavy use of so-called “game engines”, modern software frameworks offering an extensive set of powerful graphics tools and cross-platform deployment. Recently, a very strong support for Virtual Reality (VR) technology has been added to such engines. In this talk we explore the usage of game engines and VR for HEP data visualization, discussing the needs, the challenges and the issues of using such technologies. We will also make use of ATLASrift, a VR application developed by the ATLAS experiment, to discuss the lessons learned while developing it using the game engine Unreal Engine, and the feedback on the use of Virtual Reality we got from users while using it at many demonstrations and public events.
With the increase of storage needs at the High-Luminosity LHC horizon, data management and access will be very challenging. The evaluation of possible solutions within the WLCG Data Organization, ...Management and Access (DOMA) is a major activity to select the most optimal from the experiment and site point of views. Four teams hosting Tier-2s for ATLAS with storage based on DPM technology have put their expertise and computing infrastructures in common to build a testbed hosting a DPM federated storage called FR-ALPES. This note describes the infrastructure put in place, its integration within the ATLAS Grid infrastructure and presents the first results.
The Higgs Machine Learning Challenge Adam-Bourdarios, C; Cowan, G; Germain-Renaud, C ...
Journal of physics. Conference series,
12/2015, Letnik:
664, Številka:
7
Journal Article
Recenzirano
Odprti dostop
The Higgs Machine Learning Challenge was an open data analysis competition that took place between May and September 2014. Samples of simulated data from the ATLAS Experiment at the LHC corresponding ...to signal events with Higgs bosons decaying to τ+τ- together with background events were made available to the public through the website of the data science organization Kaggle (kaggle.com). Participants attempted to identify the search region in a space of 30 kinematic variables that would maximize the expected discovery significance of the signal process. One of the primary goals of the Challenge was to promote communication of new ideas between the Machine Learning (ML) and HEP communities. In this regard it was a resounding success, with almost 2,000 participants from HEP, ML and other areas. The process of understanding and integrating the new ideas, particularly from ML into HEP, is currently underway.
A recent common theme among HEP computing is exploitation of opportunistic resources in order to provide the maximum statistics possible for Monte Carlo simulation. Volunteer computing has been used ...over the last few years in many other scientific fields and by CERN itself to run simulations of the LHC beams. The ATLAS@Home project was started to allow volunteers to run simulations of collisions in the ATLAS detector. So far many thousands of members of the public have signed up to contribute their spare CPU cycles for ATLAS, and there is potential for volunteer computing to provide a significant fraction of ATLAS computing resources. Here we describe the design of the project, the lessons learned so far and the future plans.
Several observables sensitive to the fragmentation of b quarks into b hadrons are measured using 36 fb−1 of √s=13 TeV proton-proton collision data collected with the ATLAS detector at the LHC. Jets ...containing b hadrons are obtained from a sample of dileptonic t¯t events, and the associated set of charged-particle tracks is separated into those from the primary pp interaction vertex and those from the displaced b-decay secondary vertex. This division is used to construct observables that characterize the longitudinal and transverse momentum distributions of the b hadron within the jet. The measurements have been corrected for detector effects and provide a test of heavy-quark-fragmentation modeling at the LHC in a system where the top-quark decay products are color connected to the proton beam remnants. The unfolded distributions are compared with the predictions of several modern Monte Carlo parton-shower generators and generator tunes, and a wide range of agreement with the data is observed, with p values varying from 5×10−4 to 0.98. These measurements complement similar measurements from e+e− collider experiments in which the b quarks originate from a color singlet Z/γ∗.
A study of B+c→J/ψD+s and B+c→J/ψD∗+s decays using 139 fb−1 of integrated luminosity collected with the ATLAS detector from s√ = 13 TeV pp collisions at the LHC is presented. The ratios of the ...branching fractions of the two decays to the branching fraction of the B+c → J/ψπ+ decay are measured: B(B+c→J/ψD+s)/B(B+c→J/ψπ+) = 2.76 ± 0.47 and B(B+c→J/ψD∗+s)/B(B+c→J/ψπ+) = 5.33 ± 0.96. The ratio of the branching fractions of the two decays is found to be B(B+c→J/ψD∗+s)/B(B+c→J/ψD∗+s) = 1.93 ± 0.26. For the B+c→J/ψD∗+s decay, the transverse polarization fraction, Γ±±/Γ, is measured to be 0.70 ± 0.11. The reported uncertainties include both the statistical and systematic components added in quadrature. The precision of the measurements exceeds that in all previous studies of these decays. These results supersede those obtained in the earlier ATLAS study of the same decays with s√ = 7 and 8 TeV pp collision data. A comparison with available theoretical predictions for the measured quantities is presented.
The yield of charged particles opposite to a Z boson with large transverse momentum (pT) is measured in 260 pb−1 of pp and 1.7 nb−1 of Pb+Pb collision data at 5.02 TeV per nucleon pair recorded ...with the ATLAS detector at the Large Hadron Collider. The Z boson tag is used to select hard-scattered partons with specific kinematics, and to observe how their showers are modified as they propagate through the quark-gluon plasma created in Pb+Pb collisions. Compared with pp collisions, charged-particle yields in Pb+Pb collisions show significant modifications as a function of charged-particle pT in a way that depends on event centrality and Z boson pT. The data are compared with a variety of theoretical calculations and provide new information about the medium-induced energy loss of partons in a pT regime difficult to measure through other channels.
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