996 research outputs found
FPGA-accelerated machine learning inference as a service for particle physics computing
New heterogeneous computing paradigms on dedicated hardware with increased
parallelization, such as Field Programmable Gate Arrays (FPGAs), offer exciting
solutions with large potential gains. The growing applications of machine
learning algorithms in particle physics for simulation, reconstruction, and
analysis are naturally deployed on such platforms. We demonstrate that the
acceleration of machine learning inference as a web service represents a
heterogeneous computing solution for particle physics experiments that
potentially requires minimal modification to the current computing model. As
examples, we retrain the ResNet-50 convolutional neural network to demonstrate
state-of-the-art performance for top quark jet tagging at the LHC and apply a
ResNet-50 model with transfer learning for neutrino event classification. Using
Project Brainwave by Microsoft to accelerate the ResNet-50 image classification
model, we achieve average inference times of 60 (10) milliseconds with our
experimental physics software framework using Brainwave as a cloud (edge or
on-premises) service, representing an improvement by a factor of approximately
30 (175) in model inference latency over traditional CPU inference in current
experimental hardware. A single FPGA service accessed by many CPUs achieves a
throughput of 600--700 inferences per second using an image batch of one,
comparable to large batch-size GPU throughput and significantly better than
small batch-size GPU throughput. Deployed as an edge or cloud service for the
particle physics computing model, coprocessor accelerators can have a higher
duty cycle and are potentially much more cost-effective.Comment: 16 pages, 14 figures, 2 table
Planning the Future of U.S. Particle Physics (Snowmass 2013): Chapter 4: Cosmic Frontier
These reports present the results of the 2013 Community Summer Study of the
APS Division of Particles and Fields ("Snowmass 2013") on the future program of
particle physics in the U.S. Chapter 4, on the Cosmic Frontier, discusses the
program of research relevant to cosmology and the early universe. This area
includes the study of dark matter and the search for its particle nature, the
study of dark energy and inflation, and cosmic probes of fundamental
symmetries.Comment: 61 page
Maskless Generation of Single Silicon Vacancy Arrays in Silicon Carbide by a Focused He+ Ion Beam
Precise generation of spin defects in solid-state systems is essential for
nanostructure fluorescence enhancement. We investigated a method for creating
single silicon vacancy defect arrays in silicon carbide using a helium-ion
microscope. Maskless and targeted generation can be realized by precisely
controlling the focused He+ ion beam with an implantation uncertainty of 60 nm.
The generated silicon vacancies were identified by measuring the optically
detected magnetic resonance spectrum and room temperature photoluminescence
spectrum. We systematically studied the effects of the implantation ion dose on
the generated silicon vacancies. After optimization, a conversion yield of ~
6.95 % and a generation rate for a single silicon vacancy of ~ 35 % were
realized. This work paves the way for the integration and engineering of color
centers to photonic structures and the application of quantum sensing based on
spin defects in silicon carbide
Dependence on pseudorapidity and on centrality of charged hadron production in PbPb collisions at âs_(NN)=2.76 TeV
A measurement is presented of the charged hadron multiplicity in hadronic
PbPb collisions, as a function of pseudorapidity and centrality, at a collision energy of
2.76TeV per nucleon pair. The data sample is collected using the CMS detector and
a minimum-bias trigger, with the CMS solenoid off. The number of charged hadrons is
measured both by counting the number of reconstructed particle hits and by forming hit
doublets of pairs of layers in the pixel detector. The two methods give consistent results.
The charged hadron multiplicity density, dN_(ch)/d_η|η=0, for head-on collisions is found to be
1612±55, where the uncertainty is dominated by systematic effects. Comparisons of these
results to previous measurements and to various models are also presented
Search for heavy long-lived charged particles in pp collisions at âs = 7 TeV
The result of a search for heavy long-lived charged particles produced in pp collisions at âs = 7 TeV source at the LHC is described. The data sample has been collected using the CMS detector and corresponds to an integrated luminosity of 5.0 fb^(â1). The inner tracking detectors are used to define a sample of events containing tracks with high momentum and high ionization energy loss. A second sample of events, which have high-momentum tracks satisfying muon identification requirements in addition to meeting high-ionization and long time-of-flight requirements, is analyzed independently. In both cases, the results are consistent with the expected background estimated from data. The results are used to establish cross section limits as a function of mass within the context of models with long-lived gluinos, scalar top quarks and scalar taus. Cross section limits on hyper-meson particles, containing new elementary long-lived hyper-quarks predicted by a vector-like confinement model, are also presented. Lower limits at 95% confidence level on the mass of gluinos (scalar top quarks) are found to be 1098 (737) GeV/c^2. A limit of 928 (626) GeV/c^2 is set for a gluino (scalar top quark) that hadronizes into a neutral bound state before reaching the muon detectors. The lower mass limit for a pair produced scalar tau is found to be 223 GeV/c^2. Mass limits for a hyper-kaon are placed at 484, 602, and 747 GeV/c^2 for hyper-Ï masses of 800, 1200, and 1600 GeV/c^2, respectively
Extraction of the gluon density of the proton at x
The gluon momentum density xg(x, Q2) of the proton was extracted at Q2 = 20 GeV2 for small values of x between 4 à 10-4 and 10-2 from the scaling violations of the proton structure function F2 measured recently by ZEUS in deep inelastic neutral current ep scattering at HERA. The extraction was performed in two ways. Firstly, using a global NLO fit to the ZEUS data on F2 at low x constrained by measurementsfrom NMC at larger x; and secondly using published approximate methods for the solution of the GLAP QCD evolution equations. Consistent results are obtained. A substantial increase of the gluon density is found at small x in comparison with the NMC result obtained at larger values of x. © 1995
- âŠ