776 research outputs found
MicroTCA implementation of synchronous Ethernet-Based DAQ systems for large scale experiments
Large LAr TPCs are among the most powerful detectors to address open problems
in particle and astro-particle physics, such as CP violation in leptonic
sector, neutrino properties and their astrophysical implications, proton decay
search etc. The scale of such detector implies severe constraints on their
readout and DAQ system. In this article we describe a data acquisition scheme
for this new generation of large detectors. The main challenge is to propose a
scalable and easy to use solution able to manage a large number of channels at
the lowest cost. It is interesting to note that these constraints are very
similar to those existing in Network Telecommunication Industry. We propose to
study how emerging technologies like ATCA and TCA could be used in
neutrino experiments. We describe the design of an Advanced Mezzanine Board
(AMC) including 32 ADC channels. This board receives 32 analogical channels at
the front panel and sends the formatted data through the TCA backplane
using a Gigabit Ethernet link. The gigabit switch of the MCH is used to
centralize and to send the data to the event building computer. The core of
this card is a FPGA (ARIA-GX from ALTERA) including the whole system except the
memories. A hardware accelerator has been implemented using a NIOS II P
and a Gigabit MAC IP. Obviously, in order to be able to reconstruct the tracks
from the events a time synchronisation system is mandatory. We decided to
implement the IEEE1588 standard also called Precision Timing Protocol, another
emerging and promising technology in Telecommunication Industry. In this
article we describe a Gigabit PTP implementation using the recovered clock of
the gigabit link. By doing so the drift is directly cancelled and the PTP will
be used only to evaluate and to correct the offset.Comment: Talk presented at the 2009 Real Time Conference, Beijing, May '09,
submitted to the proceeding
Combatting intimate partner violence: representations of social and healthcare personnel working with gender-based violence interventions
Intimate partner violence (IPV) has been declared a global epidemic by the World Health Organization. Although the attention paid to both the perpetrators and victims of gender-based violence has increased, scientific research is still lacking in regard to the representations of operators involved in interventions and management. Therefore, the following study explores how the representations of operators affect how gender violence can be managed and combatted through an ecological approach to this phenomenon, in addition to highlighting the roles of organizationallevel services and their cultural and symbolic substrates. In total, 35 health and social professionals were interviewed and textual materials were analyzed by thematic analysis. The evidence suggests that services contrasting gender-based violence utilize different representations and management approaches. The authors hope that these differences can become a resource, rather than a limitation, when combatting gender-based violence through the construction of more integrated networks and a greater dialogue among different services, in order to make interventions designed to combat gender-based violence more effective
The Drift Chambers Of The Nomad Experiment
We present a detailed description of the drift chambers used as an active
target and a tracking device in the NOMAD experiment at CERN. The main
characteristics of these chambers are a large area, a self supporting structure
made of light composite materials and a low cost. A spatial resolution of 150
microns has been achieved with a single hit efficiency of 97%.Comment: 42 pages, 26 figure
The neutrino signal at HALO: learning about the primary supernova neutrino fluxes and neutrino properties
Core-collapse supernova neutrinos undergo a variety of phenomena when they
travel from the high neutrino density region and large matter densities to the
Earth. We perform analytical calculations of the supernova neutrino fluxes
including collective effects due to the neutrino-neutrino interactions, the
Mikheev-Smirnov-Wolfenstein (MSW) effect due to the neutrino interactions with
the background matter and decoherence of the wave packets as they propagate in
space. We predict the numbers of one- and two-neutron charged and
neutral-current electron-neutrino scattering on lead events. We show that, due
to the energy thresholds, the ratios of one- to two-neutron events are
sensitive to the pinching parameters of neutrino fluxes at the neutrinosphere,
almost independently of the presently unknown neutrino properties. Besides,
such events have an interesting sensitivity to the spectral split features that
depend upon the presence/absence of energy equipartition among neutrino
flavors. Our calculations show that a lead-based observatory like the Helium
And Lead Observatory (HALO) has the potential to pin down important
characteristics of the neutrino fluxes at the neutrinosphere, and provide us
with information on the neutrino transport in the supernova core.Comment: 30 pages, 12 figures, 6 tables, minor correction
Low energy neutrino scattering measurements at future Spallation Source facilities
In the future several Spallation Source facilities will be available
worldwide. Spallation Sources produce large amount of neutrinos from
decay-at-rest muons and thus can be well adapted to accommodate
state-of-the-art neutrino experiments. In this paper low energy neutrino
scattering experiments that can be performed at such facilities are reviewed.
Estimation of expected event rates are given for several nuclei, electrons and
protons at a detector located close to the source. A neutrino program at
Spallation Sources comprises neutrino-nucleus cross section measurements
relevant for neutrino and core-collapse supernova physics, electroweak tests
and lepton-flavor violation searches.Comment: 12 pages, 4 figures, 5 table
Measurement of the two-photon absorption cross-section of liquid argon with a time projection chamber
This paper reports on laser-induced multiphoton ionization at 266 nm of
liquid argon in a time projection chamber (LAr TPC) detector. The electron
signal produced by the laser beam is a formidable tool for the calibration and
monitoring of next-generation large-mass LAr TPCs. The detector that we
designed and tested allowed us to measure the two-photon absorption
cross-section of LAr with unprecedented accuracy and precision:
sigma_ex=(1.24\pm 0.10stat \pm 0.30syst) 10^{-56} cm^4s{-1}.Comment: 15 pages, 9 figure
Low Energy Electron and Nuclear Recoil Thresholds in the DRIFT-II Negative Ion TPC for Dark Matter Searches
Understanding the ability to measure and discriminate particle events at the
lowest possible energy is an essential requirement in developing new
experiments to search for weakly interacting massive particle (WIMP) dark
matter. In this paper we detail an assessment of the potential sensitivity
below 10 keV in the 1 m^3 DRIFT-II directionally sensitive, low pressure,
negative ion time projection chamber (NITPC), based on event-by-event track
reconstruction and calorimetry in the multiwire proportional chamber (MWPC)
readout. By application of a digital smoothing polynomial it is shown that the
detector is sensitive to sulfur and carbon recoils down to 2.9 and 1.9 keV
respectively, and 1.2 keV for electron induced events. The energy sensitivity
is demonstrated through the 5.9 keV gamma spectrum of 55Fe, where the energy
resolution is sufficient to identify the escape peak. The effect a lower energy
sensitivity on the WIMP exclusion limit is demonstrated. In addition to recoil
direction reconstruction for WIMP searches this sensitivity suggests new
prospects for applications also in KK axion searches
Prediction of Neutrino Fluxes in the NOMAD Experiment
The method developed for the calculation of the flux and composition of the
West Area Neutrino Beam used by NOMAD in its search for neutrino oscillations
is described. The calculation is based on particle production rates computed
using a recent version of FLUKA and modified to take into account the cross
sections measured by the SPY and NA20 experiments. These particles are
propagated through the beam line taking into account the material and magnetic
fields they traverse. The neutrinos produced through their decays are tracked
to the NOMAD detector. The fluxes of the four neutrino flavours at NOMAD are
predicted with an uncertainty of about 8% for nu(mu) and nu(e), 10% for
antinu(mu), and 12% for antinu(e). The energy-dependent uncertainty achieved on
the R(e, mu) prediction needed for a nu(mu)->nu(e) oscillation search ranges
from 4% to 7%, whereas the overall normalization uncertainty on this ratio is
4.2%.Comment: 43 pages, 20 figures. Submitted to Nucl. Phys.
Search for nu(mu)-->nu(e) Oscillations in the NOMAD Experiment
We present the results of a search for nu(mu)-->nu(e) oscillations in the
NOMAD experiment at CERN. The experiment looked for the appearance of nu(e) in
a predominantly nu(mu) wide-band neutrino beam at the CERN SPS. No evidence for
oscillations was found. The 90% confidence limits obtained are delta m^2 < 0.4
eV^2 for maximal mixing and sin^2(2theta) < 1.4x10^{-3} for large delta m^2.
This result excludes the LSND allowed region of oscillation parameters with
delta m^2 > 10 eV^2.Comment: 19 pages, 8 figures. Submitted to Phys. Lett.
Final NOMAD results on nu_mu->nu_tau and nu_e->nu_tau oscillations including a new search for nu_tau appearance using hadronic tau decays
Results from the nu_tau appearance search in a neutrino beam using the full
NOMAD data sample are reported. A new analysis unifies all the hadronic tau
decays, significantly improving the overall sensitivity of the experiment to
oscillations. The "blind analysis" of all topologies yields no evidence for an
oscillation signal. In the two-family oscillation scenario, this sets a 90%
C.L. allowed region in the sin^2(2theta)-Delta m^2 plane which includes
sin^2(2theta)<3.3 x 10^{-4} at large Delta m^2 and Delta m^2 < 0.7 eV^2/c^4 at
sin^2(2theta)=1. The corresponding contour in the nu_e->nu_tau oscillation
hypothesis results in sin^2(2theta)<1.5 x 10^{-2} at large Delta m^2 and Delta
m^2 < 5.9 eV^2/c^4 at sin^2(2theta)=1. We also derive limits on effective
couplings of the tau lepton to nu_mu or nu_e.Comment: 46 pages, 16 figures, Latex, to appear on Nucl. Phys.
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