343 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
Muon tomography applied to active volcanoes
Muon tomography is a generic imaging method using the differential absorption
of cosmic muons by matter. The measured contrast in the muons flux reflects the
matter density contrast as it does in conventional medical imaging. The
applications to volcanology present may advantadges induced by the features of
the target itself: limited access to dangerous zones, impossible use of
standard boreholes information, harsh environmental conditions etc. The
Diaphane project is one of the largest and leading collaboration in the field
and the present article summarizes recent results collected on the Lesser
Antilles, with a special emphasis on the Soufri\`ere of Guadeloupe.Comment: 7 pages, 7 figures, International Conference on New
Photo-detectors,PhotoDet2015, 6-9 July 2015, Moscow, Troitsk, Russia.
Submitted to Po
Gebunden-freie Paarerzeugung in kombinierten Laser- und Coulombfeldern
In der vorliegenden Arbeit wird der Prozess der gebunden-freien Paarerzeugung von Elektronen und Positronen in kombinierten Laser- und Coulombfeldern untersucht. Es wird angenommen, dass ein relativistischer Ionenstrahl frontal mit einem intensiven Röntgenlaserstrahl kollidiert. Das Elektron-Positron-Paar wird durch simultane Absorption mehrerer Laserphotonen in einem nichtlinearen Prozess erzeugt. Der Einfang der Elektronen wird sowohl für den Grundzustand als auch für angeregte Zustände untersucht. Es wird die Prozesswahrscheinlichkeit im Rahmen der relativistischen Quantenmechanik berechnet. Für diesen nichtlinearen Prozess starker Laserfelder kann keine gewöhnliche Störungsentwicklung angewandt werden; stattdessen wird hier die Strong-Field-Approximation benutzt, welche den Einfluss des Coulombfelds auf das Positron vernachlässigt. Es werden ein analytisches Ergebnis für die Übergangsamplitude gefunden und numerische Ergebnisse für die Paarproduktionsraten mit Parametern des geplanten Röntgenlasers bei DESY vorgestellt. Hauptresultate sind, dass gebunden-freie Paarproduktion zu endlich hohen Raten führt, und diese von vergleichbarer Größenordnung wie für frei-freie Paarproduktion sind. In naher Zukunft wird die experimentelle Beobachtung des untersuchten Prozesses möglich sein
Translatability of WGS typing results can simplify data exchange for surveillance and control of Listeria monocytogenes
Where classical epidemiology has proven to be inadequate for surveillance and control of foodborne pathogens, molecular epidemiology, using genomic typing methods, can add value. However, the analysis of whole genome sequencing (WGS) data varies widely and is not yet fully harmonised. We used genomic data on 494 Listeria monocytogenes isolates from readyto- eat food products and food processing environments deposited in the strain collection of the German National Reference Laboratory to compare various procedures for WGS data analysis and to evaluate compatibility of results. Two different core genome multilocus sequence typing (cgMLST) schemes, different reference genomes in single nucleotide polymorphism (SNP) analysis and commercial as well as opensource software were compared. Correlation of allele distances from the different cgMLST approaches was high, ranging from 0.97 to 1, and unified thresholds yielded higher clustering concordance than schemespecific thresholds. The number of detected SNP differences could be increased up to a factor of 3.9 using a specific reference genome compared with a general one. Additionally, specific reference genomes improved comparability of SNP analysis results obtained using different software tools. The use of a closed or a draft specific reference genome did not make a difference. The harmonisation of WGS data analysis will finally guarantee seamless data exchange, but, in the meantime, knowledge on threshold values that lead to comparable clustering of isolates by different methods may improve communication between laboratories. We therefore established a translation code between commonly applied cgMLST and SNP methods based on optimised clustering concordances. This code can work as a first filter to identify WGS- based typing matches resulting from different methods, which opens up a new perspective for data exchange and thereby accelerates timecritical analyses, such as in outbreak investigations
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