46 research outputs found
Understanding and Coping with Hardware and Software Failures in a Very Large Trigger Farm
When thousands of processors are involved in performing event filtering on a
trigger farm, there is likely to be a large number of failures within the
software and hardware systems. BTeV, a proton/antiproton collider experiment at
Fermi National Accelerator Laboratory, has designed a trigger, which includes
several thousand processors. If fault conditions are not given proper
treatment, it is conceivable that this trigger system will experience failures
at a high enough rate to have a negative impact on its effectiveness. The RTES
(Real Time Embedded Systems) collaboration is a group of physicists, engineers,
and computer scientists working to address the problem of reliability in
large-scale clusters with real-time constraints such as this. Resulting
infrastructure must be highly scalable, verifiable, extensible by users, and
dynamically changeable.Comment: Paper for the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003. PSN THGT00
Big Data in HEP: A comprehensive use case study
Experimental Particle Physics has been at the forefront of analyzing the
worlds largest datasets for decades. The HEP community was the first to develop
suitable software and computing tools for this task. In recent times, new
toolkits and systems collectively called Big Data technologies have emerged to
support the analysis of Petabyte and Exabyte datasets in industry. While the
principles of data analysis in HEP have not changed (filtering and transforming
experiment-specific data formats), these new technologies use different
approaches and promise a fresh look at analysis of very large datasets and
could potentially reduce the time-to-physics with increased interactivity. In
this talk, we present an active LHC Run 2 analysis, searching for dark matter
with the CMS detector, as a testbed for Big Data technologies. We directly
compare the traditional NTuple-based analysis with an equivalent analysis using
Apache Spark on the Hadoop ecosystem and beyond. In both cases, we start the
analysis with the official experiment data formats and produce publication
physics plots. We will discuss advantages and disadvantages of each approach
and give an outlook on further studies needed.Comment: Proceedings for 22nd International Conference on Computing in High
Energy and Nuclear Physics (CHEP 2016
Novel deep learning methods for track reconstruction
For the past year, the HEP.TrkX project has been investigating machine
learning solutions to LHC particle track reconstruction problems. A variety of
models were studied that drew inspiration from computer vision applications and
operated on an image-like representation of tracking detector data. While these
approaches have shown some promise, image-based methods face challenges in
scaling up to realistic HL-LHC data due to high dimensionality and sparsity. In
contrast, models that can operate on the spacepoint representation of track
measurements ("hits") can exploit the structure of the data to solve tasks
efficiently. In this paper we will show two sets of new deep learning models
for reconstructing tracks using space-point data arranged as sequences or
connected graphs. In the first set of models, Recurrent Neural Networks (RNNs)
are used to extrapolate, build, and evaluate track candidates akin to Kalman
Filter algorithms. Such models can express their own uncertainty when trained
with an appropriate likelihood loss function. The second set of models use
Graph Neural Networks (GNNs) for the tasks of hit classification and segment
classification. These models read a graph of connected hits and compute
features on the nodes and edges. They adaptively learn which hit connections
are important and which are spurious. The models are scaleable with simple
architecture and relatively few parameters. Results for all models will be
presented on ACTS generic detector simulated data.Comment: CTD 2018 proceeding
Graph Neural Networks for Particle Reconstruction in High Energy Physics detectors
Pattern recognition problems in high energy physics are notably different
from traditional machine learning applications in computer vision.
Reconstruction algorithms identify and measure the kinematic properties of
particles produced in high energy collisions and recorded with complex detector
systems. Two critical applications are the reconstruction of charged particle
trajectories in tracking detectors and the reconstruction of particle showers
in calorimeters. These two problems have unique challenges and characteristics,
but both have high dimensionality, high degree of sparsity, and complex
geometric layouts. Graph Neural Networks (GNNs) are a relatively new class of
deep learning architectures which can deal with such data effectively, allowing
scientists to incorporate domain knowledge in a graph structure and learn
powerful representations leveraging that structure to identify patterns of
interest. In this work we demonstrate the applicability of GNNs to these two
diverse particle reconstruction problems
Graph Neural Networks for Particle Reconstruction in High Energy Physics detectors
Pattern recognition problems in high energy physics are notably different
from traditional machine learning applications in computer vision.
Reconstruction algorithms identify and measure the kinematic properties of
particles produced in high energy collisions and recorded with complex detector
systems. Two critical applications are the reconstruction of charged particle
trajectories in tracking detectors and the reconstruction of particle showers
in calorimeters. These two problems have unique challenges and characteristics,
but both have high dimensionality, high degree of sparsity, and complex
geometric layouts. Graph Neural Networks (GNNs) are a relatively new class of
deep learning architectures which can deal with such data effectively, allowing
scientists to incorporate domain knowledge in a graph structure and learn
powerful representations leveraging that structure to identify patterns of
interest. In this work we demonstrate the applicability of GNNs to these two
diverse particle reconstruction problems.Comment: Presented at NeurIPS 2019 Workshop "Machine Learning and the Physical
Sciences
The HEP.TrkX Project: deep neural networks for HL-LHC online and offline tracking
Particle track reconstruction in dense environments such as the detectors of the High Luminosity Large Hadron Collider (HL-LHC) is a challenging pattern recognition problem. Traditional tracking algorithms such as the combinatorial Kalman Filter have been used with great success in LHC experiments for years. However, these state-of-the-art techniques are inherently sequential and scale poorly with the expected increases in detector occupancy in the HL-LHC conditions. The HEP.TrkX project is a pilot project with the aim to identify and develop cross-experiment solutions based on machine learning algorithms for track reconstruction. Machine learning algorithms bring a lot of potential to this problem thanks to their capability to model complex non-linear data dependencies, to learn effective representations of high-dimensional data through training, and to parallelize easily on high-throughput architectures such as GPUs. This contribution will describe our initial explorations into this relatively unexplored idea space. We will discuss the use of recurrent (LSTM) and convolutional neural networks to find and fit tracks in toy detector data
Graph Neural Network for Object Reconstruction in Liquid Argon Time Projection Chambers
This paper presents a graph neural network (GNN) technique for low-level
reconstruction of neutrino interactions in a Liquid Argon Time Projection
Chamber (LArTPC). GNNs are still a relatively novel technique, and have shown
great promise for similar reconstruction tasks in the LHC. In this paper, a
multihead attention message passing network is used to classify the
relationship between detector hits by labelling graph edges, determining
whether hits were produced by the same underlying particle, and if so, the
particle type. The trained model is 84% accurate overall, and performs best on
the EM shower and muon track classes. The model's strengths and weaknesses are
discussed, and plans for developing this technique further are summarised.Comment: 7 pages, 3 figures, submitted to the 25th International Conference on
Computing in High-Energy and Nuclear Physic