795 research outputs found
Data production models for the CDF experiment
The data production for the CDF experiment is conducted on a large Linux PC
farm designed to meet the needs of data collection at a maximum rate of 40
MByte/sec. We present two data production models that exploits advances in
computing and communication technology. The first production farm is a
centralized system that has achieved a stable data processing rate of
approximately 2 TByte per day. The recently upgraded farm is migrated to the
SAM (Sequential Access to data via Metadata) data handling system. The software
and hardware of the CDF production farms has been successful in providing large
computing and data throughput capacity to the experiment.Comment: 8 pages, 9 figures; presented at HPC Asia2005, Beijing, China, Nov 30
- Dec 3, 200
Effect of Pt vacancies on magnetotransport of Weyl semimetal candidate GdPtSb epitaxial films
We examine the effects of Pt vacancies on the magnetotransport properties of
Weyl semimetal candidate GdPtSb films, grown by molecular beam epitaxy on
c-plane sapphire. Rutherford backscattering spectrometry (RBS) and x-ray
diffraction measurements suggest that phase pure GdPtSb films can
accommodate up to Pt vacancies (), which act as acceptors as
measured by Hall effect. Two classes of electrical transport behavior are
observed. Pt-deficient films display a metallic temperature dependent
resistivity (d/dT0). The longitudinal magnetoresistance (LMR, magnetic
field parallel to electric field ) is more negative
than transverse magnetoresistance (TMR, ),
consistent with the expected chiral anomaly for a Weyl semimetal. The
combination of Pt-vacancy disorder and doping away from the expected Weyl
nodes; however, suggests conductivity fluctuations may explain the negative LMR
rather than chiral anomaly. Samples closer to stoichiometry display the
opposite behavior: semiconductor-like resistivity (d/dT0) and more
negative transverse magnetoresistance than longitudinal magnetoresistance.
Hysteresis and other nonlinearities in the low field Hall effect and
magnetoresistance suggest that spin disorder scattering, and possible
topological Hall effect, may dominate the near stoichiometric samples. Our
findings highlight the complications of transport-based identification of Weyl
nodes, but point to possible topological spin textures in GdPtSb
Data processing model for the CDF experiment
The data processing model for the CDF experiment is described. Data
processing reconstructs events from parallel data streams taken with different
combinations of physics event triggers and further splits the events into
datasets of specialized physics datasets. The design of the processing control
system faces strict requirements on bookkeeping records, which trace the status
of data files and event contents during processing and storage. The computing
architecture was updated to meet the mass data flow of the Run II data
collection, recently upgraded to a maximum rate of 40 MByte/sec. The data
processing facility consists of a large cluster of Linux computers with data
movement managed by the CDF data handling system to a multi-petaByte Enstore
tape library. The latest processing cycle has achieved a stable speed of 35
MByte/sec (3 TByte/day). It can be readily scaled by increasing CPU and
data-handling capacity as required.Comment: 12 pages, 10 figures, submitted to IEEE-TN
Effects of germination on chemical composition and antioxidant activity of flaxseed (<em>Linum usitatissimum</em> L) oil
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CDF II production farm project
We describe the architecture and discuss our operational experience in running the off-line reconstruction farm of the CDFII experiment. The Linux PC-based farm performs a wide set of tasks,ranging from producing calibrations and primary event reconstruction to large scale ntuple production.The farm control software uses a standard Condor toolkit and the data handling part is based on SAM (Sequential Access via Metadata)software.During its lifetime,the CDFII experiment will integrate a large amount of data (several petabytes)and the data processing chain is one of the key components of the successful physics program of the experiment
Search for bottom squarks in pbarp collisions at sqrt(s)=1.8 TeV
We report on a search for bottom squarks produced in pbarp collisions at
sqrt(s) = 1.8 TeV using the D0 detector at Fermilab. Bottom squarks are assumed
to be produced in pairs and to decay to the lightest supersymmetric particle
(LSP) and a b quark with branching fraction of 100%. The LSP is assumed to be
the lightest neutralino and stable. We set limits on the production cross
section as a function of bottom squark mass and LSP mass.Comment: 5 pages, Latex. submitted 3-12-1999 to PRD - Rapid Communicatio
Search for Squarks and Gluinos in Events Containing Jets and a Large Imbalance in Transverse Energy
Using data corresponding to an integrated luminosity of 79 pb-1, D0 has
searched for events containing multiple jets and large missing transverse
energy in pbar-p collisions at sqrt(s)=1.8 TeV at the Fermilab Tevatron
collider. Observing no significant excess beyond what is expected from the
standard model, we set limits on the masses of squarks and gluinos and on the
model parameters m_0 and m_1/2, in the framework of the minimal low-energy
supergravity models of supersymmetry. For tan(beta) = 2 and A_0 = 0, with mu <
0, we exclude all models with m_squark < 250 GeV/c^2. For models with equal
squark and gluino masses, we exclude m < 260 GeV/c^2.Comment: 10 pages, 3 figures, Submitted to PRL, Fixed typo on page bottom of
p. 6 (QCD multijet background is 35.4 events
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