2,747 research outputs found
On event-by-event fluctuations in nuclear collisions
We demonstrate that a new type of analysis in heavy-ion collisions, based on an event-by-event analysis of the transverse momentum distribution, allows us to obtain information on secondary interactions and collective behaviour that is not available from the inclusive spectra. Using a random walk model as a simple phenomenological description of initial state scattering in collisions with heavy nuclei, we show that the event-by-event measurement allows a quantitative determination of this effect, well within the resolution achievable with the new generation of large acceptance hadron spectrometers. The preliminary data of the NA49 collaboration on transverse momentum fluctuations indicate qualitatively different behaviour than that obtained within the random walk model. The results are discussed in relation to the thermodynamic and hydrodynamic description of nuclear collisions
The PROOF Distributed Parallel Analysis Framework based on ROOT
The development of the Parallel ROOT Facility, PROOF, enables a physicist to
analyze and understand much larger data sets on a shorter time scale. It makes
use of the inherent parallelism in event data and implements an architecture
that optimizes I/O and CPU utilization in heterogeneous clusters with
distributed storage. The system provides transparent and interactive access to
gigabytes today. Being part of the ROOT framework PROOF inherits the benefits
of a performant object storage system and a wealth of statistical and
visualization tools. This paper describes the key principles of the PROOF
architecture and the implementation of the system. We will illustrate its
features using a simple example and present measurements of the scalability of
the system. Finally we will discuss how PROOF can be interfaced and make use of
the different Grid solutions.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, CA, USA, March 2003, 5 pages, LaTeX, 4 eps figures. PSN
TULT00
Hard Probe Capabilities of CMS in Heavy Ion Collisions at the LHC
Heavy ion collisions at the Large Hadron Collider (LHC) will produce strongly
interacting matter at unprecedented energy densities. At LHC collision
energies, new hard probes of the dense initial collision system will become
readily available. We present an overview of the capabilities of the Compact
Muon Solenoid (CMS) detector to use these probes for a detailed study of QCD
phenomenology at the highest energy densities.Comment: Proceedings for Hard Probes 2006, Asilomar; CMS Conference Report
2006/06
On Event-by-Event Fluctuations in Nuclear Collisions
We demonstrate that a new type of analysis in heavy-ion collisions, based on
an event-by-event analysis of the transverse momentum distribution, allows us
to obtain information on secondary interactions and collective behaviour that
is not available from the inclusive spectra. Using a random walk model as a
simple phenomenological description of initial state scattering in collisions
with heavy nuclei, we show that the event-by-event measurement allows a
quantitative determination of this effect, well within the resolution
achievable with the new generation of large acceptance hadron spectrometers.
The preliminary data of the NA49 collaboration on transverse momentum
fluctuations indicate qualitatively different behaviour than that obtained
within the random walk model. The results are discussed in relation to the
thermodynamic and hydrodynamic description of nuclear collisions.Comment: 9 page
Rational Strain Engineering in Delafossite Oxides for Highly Efficient Hydrogen Evolution Catalysis in Acidic Media
The rational design of hydrogen evolution reaction (HER) electrocatalysts
which are competitive with platinum is an outstanding challenge to make
power-to-gas technologies economically viable. Here, we introduce the
delafossites PdCrO, PdCoO and PtCoO as a new family of
electrocatalysts for the HER in acidic media. We show that in PdCoO the
inherently strained Pd metal sublattice acts as a pseudomorphic template for
the growth of a strained (by +2.3%) Pd rich capping layer under reductive
conditions. The surface modification continuously improves the electrocatalytic
activity by simultaneously increasing the exchange current density j from 2
to 5 mA/cm and by reducing the Tafel slope down to 38 mV/decade,
leading to overpotentials < 15 mV for 10 mA/cm, superior
to bulk platinum. The greatly improved activity is attributed to the in-situ
stabilization of a -palladium hydride phase with drastically enhanced
surface catalytic properties with respect to pure or nanostructured palladium.
These findings illustrate how operando induced electrodissolution can be used
as a top-down design concept for rational surface and property engineering
through the strain-stabilized formation of catalytically active phases
Mobile 3D sensor for documenting maintenance processes of large complex structures
With the new handheld goSCOUT3D sensor system, the entire surface of complex industrial machinery spanning several meters can be captured three-dimensionally within a matter of minutes. In addition, a comprehensive photo collection is registered and precisely assigned to the corresponding 3D object points in one hybrid 2D/3D model. At the basis of the robust 3D digitization are the measuring principles of photogrammetric reconstruction using a high-resolution color camera and simultaneous localization and imaging using a tracking unit. Following image acquisition, the process leading to generation of the complete hybrid model is fully automated. Under continuous movement of the sensor head, up to six images per second and a total of up to several thousand images can be recorded. Those images are then aligned in 3D space and used to reconstruct the 3D model. Results regarding accuracy measurements are presented as well as application examples of digitized technical machinery under maintenance and inspection
The Hot QCD White Paper: Exploring the Phases of QCD at RHIC and the LHC
The past decade has seen huge advances in experimental measurements made in
heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) and more
recently at the Large Hadron Collider (LHC). These new data, in combination
with theoretical advances from calculations made in a variety of frameworks,
have led to a broad and deep knowledge of the properties of thermal QCD matter.
Increasingly quantitative descriptions of the quark-gluon plasma (QGP) created
in these collisions have established that the QGP is a strongly coupled liquid
with the lowest value of specific viscosity ever measured. However, much
remains to be learned about the precise nature of the initial state from which
this liquid forms, how its properties vary across its phase diagram and how, at
a microscopic level, the collective properties of this liquid emerge from the
interactions among the individual quarks and gluons that must be visible if the
liquid is probed with sufficiently high resolution. This white paper, prepared
by the Hot QCD Writing Group as part of the U.S. Long Range Plan for Nuclear
Physics, reviews the recent progress in the field of hot QCD and outlines the
scientific opportunities in the next decade for resolving the outstanding
issues in the field.Comment: 110 pages, 33 figures, 429 references. Prepared as part of the U.S.
Long-Range Plan for Nuclear Physic
Thoughts on opportunities from high-energy nuclear collisions
This document summarizes thoughts on opportunities from high-energy nuclear
collisions.Comment: 10 pages, pd
Thoughts on heavy-ion physics in the high luminosity era: the soft sector
This document summarizes thoughts on opportunities in the soft-QCD sector
from high-energy nuclear collisions at high luminosities.Comment: 19 page
- …