104 research outputs found
Blast-wave model description of the Hanbury-Brown--Twiss radii in pp collisions at LHC energies
The blast wave model is applied to the recent data on HBT radii in pp
collisions, measured by the ALICE collaboration. A reasonable description of
data is obtained for a rather low temperature of the kinetic freeze-out, T ~
100 MeV, and the transverse profile corresponding to the emission from a shell
of a fairly small width 2 d ~ 1.5 fm. The size and the life-time of the
produced system are determined for various multiplicities of the produced
particles.Comment: version published in J. Phys.
Finite size of hadrons and Bose-Einstein correlations in collisions at 7 TeV
Space-time correlations between produced particles, induced by the composite
nature of hadrons, imply specific changes in the properties of the correlation
functions for identical particles. The expected magnitude of these effects is
evaluated using the recently published blast-wave model analysis of the data
for collisions at = 7 TeV.Comment: The updated version matching the published PLB articl
Bose-Einstein correlations and thermal cluster formation in high-energy collisions
The blast wave model is generalized to include the production of thermal
clusters, as suggested by the apparent success of the statistical model of
particle production at high energies. The formulae for the HBT correlation
functions and the corresponding HBT radii are derived.Comment: minor text corrections, a few references added, version accepted for
publication in APP
Implementation of On-Line Data Reduction Algorithms in the CMS Endcap Preshower Data Concentrator Card
The CMS Endcap Preshower (ES) sub-detector comprises 4288 silicon sensors, each containing 32 strips. The data are transferred from the detector to the counting room via 1208 optical fibres running at 800Mbps. Each fibre carries data from 2, 3 or 4 sensors. For the readout of the Preshower, a VME-based system - the Endcap Preshower Data Concentrator Card (ES-DCC) is currently under development. The main objective of each readout board is to acquire on-detector data from up to 36 optical links, perform on-line data reduction (zero suppression) and pass the concentrated data to the CMS event builder. This document presents the conceptual design of the Reduction Algorithms as well as their implementation into the ES-DCC FPGAs. The algorithms implemented into the ES-DCC resulted in a reduction factor of ~20
GLISSANDO: GLauber Initial-State Simulation AND mOre
GLISSANDO is a Glauber Monte-Carlo generator for early-stages of relativistic
heavy-ion collisions, written in c++ and interfaced to Root. Several models are
implemented: the wounded-nucleon model, the binary collisions model, the mixed
model, and the model with hot-spots. Subtleties of the distribution of nucleon
in the nucleus are discussed. The original geometric distribution of sources in
the transverse plane can be superimposed with a statistical distribution
simulating the dispersion in the generated transverse energy in each individual
collision. The program generates inter alia the fixed axes (standard) and
variable-axes (participant) two-dimensional profiles of the density of sources
in the transverse plane and their Fourier components. These profiles can be
used in further analyses of physical phenomena, such as the the jet quenching,
event-by-event hydrodynamics, or analysis of the elliptic flow and its
fluctuations. Characteristics of the event (multiplicities, eccentricities,
Fourier coefficients, etc.) are evaluated and stored in a file for further
off-line studies. A number of scripts is provided for that purpose. Supplied
variants of the code can also be used for the proton-nucleus and
deuteron-nucleus collisions.Comment: Updated ver. 1.6 of the code available at
http://www.pu.kielce.pl/homepages/mryb/GLISSANDO
Highly-anisotropic and strongly-dissipative hydrodynamics with transverse expansion
A recently formulated framework of highly-anisotropic and
strongly-dissipative hydrodynamics (ADHYDRO) is used to describe the evolution
of matter created in ultra-relativistic heavy-ion collisions. New developments
of the model contain: the inclusion of asymmetric transverse expansion
(combined with the longitudinal boost-invariant flow) and comparisons of the
model results with the RHIC data, which have become possible after coupling of
ADHYDRO with THERMINATOR. Various soft-hadronic observables (the
transverse-momentum spectra, the elliptic flow coefficient v_2, and the HBT
radii) are calculated for different initial conditions characterized by the
value of the initial pressure asymmetry. We find that as long as the initial
energy density profile is unchanged the calculated observables remain
practically the same. This result indicates the insensitivity of the analyzed
observables to the initial anisotropy of pressure and suggests that the
complete thermalization of the system may be delayed to easily acceptable times
of about 1 fm/c
The CMS Electromagnetic Calorimeter Data Acquisition System at the 2006 Test Beam
The Electromagnetic Calorimeter of the CMS experiment at the CERN LHC is an homogeneous calorimeter made of about 80000 Lead Tungstate crystals. From June to November 2006, eleven barrel Supermodules (1700 crystals each) were exposed to beam at CERN SPS, both in stand-alone and in association with portions of the Hadron Calorimeter. We present the description of the system used to configure and readout the calorimeter during this period. The full set of final readout electronics boards was employed, together with the pre-series version of the data acquisition software. During this testbeam, the hardware and software concepts for the final system were validated and the successfull operation of all the ten supermodules was ensured
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