1,969 research outputs found
Test Beam Results of Geometry Optimized Hybrid Pixel Detectors
The Multi-Chip-Module-Deposited (MCM-D) technique has been used to build
hybrid pixel detector assemblies. This paper summarises the results of an
analysis of data obtained in a test beam campaign at CERN. Here, single chip
hybrids made of ATLAS pixel prototype read-out electronics and special sensor
tiles were used. They were prepared by the Fraunhofer Institut fuer
Zuverlaessigkeit und Mikrointegration, IZM, Berlin, Germany. The sensors
feature an optimized sensor geometry called equal sized bricked. This design
enhances the spatial resolution for double hits in the long direction of the
sensor cells.Comment: Contribution to Proceedings of Pixel2005 Workshop, Bonn Germany 200
System Tests of the ATLAS Pixel Detector
The innermost part of the ATLAS (A Toroidal LHC ApparatuS) experiment at the
LHC (Large Hadron Collider) will be a pixel detector, which is presently under
construction. Once installed into the experimental area, access will be
extremely limited. To ensure that the integrated detector assembly operates as
expected, a fraction of the detector which includes the power supplies and
monitoring system, the optical readout, and the pixel modules themselves, has
been assembled and operated in a laboratory setting for what we refer to as
system tests. Results from these tests are presented.Comment: 5 Pages, 9 Figures, to appear in Proceedings of the Eleventh Workshop
on Electronics for LHC and Future Experiment
PDV camac controller KFA ZEL NE 365
Rechner zur Steuerung von industriellen Prozessen und zugehörige geeignete Datenübertragungssysteme sind seit vielen Jahren erfolgreich im Einsatz. In jüngster Zeit kommen zur Steuerung räumlich getrennter und weit auseinanderliegender Prozesse aus wirtschaftlichen Gründen zunehmend Bussysteme mit serieller Datenübertragung zur Anwendung. Im PDV-Arbeitskreis TP 30 wurde ein Prozeßdatenübertragungssystem entworfen, das für alle industriellen Anwendungen geeignet erscheint, bei denen große Entfernungenzu überbrücken sind, Echtzeitbedingungen einzuhalten sind und hohe Betriebssicherheit wichtiger ist als hohe übertragungsraten /1/.Bei der Festlegung einer Leitungsstruktur spielen hohe Betriebssicherheit und die Notwendigkeit einer leistungsfähigen Alarmerkennung eine ausschlaggebende Rolle. Eine hohe Betriebssicherheit wird u. a. erreicht, wenn eine von keinem Signalverstärker unterbrochene Leitung, d. h. eine bidirektionale Leitung, verwendet wird. Wird diese Leitung an der aktiven Steuerstation zu einemRing geschlossen, besteht die Möglichkeit, Leitungsunterbrechungen zu erkennen und die Nachricht auf Übertragungsfehler zu überprüfen. Eine mögliche Systemvariante liegt in der Verwendung von zwei getrennten Leitungen (siehe Abb. 0-1). Dabei dient die eine Leitung der Übertragung von Nachrichten (Steuerstation- Unterstation- Steuerstation), die andere der Übertragung von Antworten (Unterstation - Steuerstation) und Alarmmeldungen, wodurch insbesondere eine effektive Alarmbehandlung ermöglichtwird. Darüber hinaus bietet eine Doppelleitung Vorteile für rückwirkungsfreie Ankopplungen über Transformatoren. Als Systemvariante für größere Entfernungen wird eine Unidirektionale Einfachringleitung empfohlen, die durch das Einschalten von Bussignalregeneratorenrealisiert werden kann - eine Maßnahme, die für große Entfernun~en erforderlich wird (s. Abbildung 0-2, vergl. /1/). [...
Enhancing the top signal at Tevatron using Neural Nets
We show that Neural Nets can be useful for top analysis at Tevatron. The main
features of and background events on a mixed sample are projected in
a single output, which controls the efficiency and purity of the
signal.Comment: 11 pages, 6 figures (not included and available from the authors),
Latex, UB-ECM-PF 94/1
Genetic algorithms and the analysis of SnIa data
The Genetic Algorithm is a heuristic that can be used to produce model
independent solutions to an optimization problem, thus making it ideal for use
in cosmology and more specifically in the analysis of type Ia supernovae data.
In this work we use the Genetic Algorithms (GA) in order to derive a null test
on the spatially flat cosmological constant model CDM. This is done in
two steps: first, we apply the GA to the Constitution SNIa data in order to
acquire a model independent reconstruction of the expansion history of the
Universe and second, we use the reconstructed in conjunction with
the Om statistic, which is constant only for the CDM model, to derive
our constraints. We find that while CDM is consistent with the data at
the level, some deviations from CDM model at low redshifts
can be accommodated.Comment: 11 pages, 7 figures, to be published in the proceedings of the 14th
Conference on Recent Developments in Gravity (NEB-14), Ioannina, Greece, 8-11
June 201
Effects of Acute Febrile Diseases on the Periodontium of Rhesus Monkeys with Reference to Poliomyelitis
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67269/2/10.1177_00220345510300050301.pd
Determination of the b quark mass at the M_Z scale with the DELPHI detector at LEP
An experimental study of the normalized three-jet rate of b quark events with
respect to light quarks events (light= \ell \equiv u,d,s) has been performed
using the CAMBRIDGE and DURHAM jet algorithms. The data used were collected by
the DELPHI experiment at LEP on the Z peak from 1994 to 2000. The results are
found to agree with theoretical predictions treating mass corrections at
next-to-leading order. Measurements of the b quark mass have also been
performed for both the b pole mass: M_b and the b running mass: m_b(M_Z). Data
are found to be better described when using the running mass. The measurement
yields: m_b(M_Z) = 2.85 +/- 0.18 (stat) +/- 0.13 (exp) +/- 0.19 (had) +/- 0.12
(theo) GeV/c^2 for the CAMBRIDGE algorithm. This result is the most precise
measurement of the b mass derived from a high energy process. When compared to
other b mass determinations by experiments at lower energy scales, this value
agrees with the prediction of Quantum Chromodynamics for the energy evolution
of the running mass. The mass measurement is equivalent to a test of the
flavour independence of the strong coupling constant with an accuracy of 7
permil.Comment: 24 pages, 10 figures, Accepted by Eur. Phys. J.
Study of Inclusive J/psi Production in Two-Photon Collisions at LEP II with the DELPHI Detector
Inclusive J/psi production in photon-photon collisions has been observed at
LEP II beam energies. A clear signal from the reaction gamma gamma -> J/psi+X
is seen. The number of observed N(J/psi -> mu+mu-) events is 36 +/- 7 for an
integrated luminosity of 617 pb^{-1}, yielding a cross-section of
sigma(J/psi+X) = 45 +/- 9 (stat) +/- 17 (syst) pb. Based on a study of the
event shapes of different types of gamma gamma processes in the PYTHIA program,
we conclude that (74 +/- 22)% of the observed J/psi events are due to
`resolved' photons, the dominant contribution of which is most probably due to
the gluon content of the photon.Comment: 13 pages, 8 figures, Accepted by Phys. Lett.
Evidence for an Excess of Soft Photons in Hadronic Decays of Z^0
Soft photons inside hadronic jets converted in front of the DELPHI main
tracker (TPC) in events of qqbar disintegrations of the Z^0 were studied in the
kinematic range 0.2 < E_gamma < 1 GeV and transverse momentum with respect to
the closest jet direction p_T < 80 MeV/c. A clear excess of photons in the
experimental data as compared to the Monte Carlo predictions is observed. This
excess (uncorrected for the photon detection efficiency) is (1.17 +/- 0.06 +/-
0.27) x 10^{-3} gamma/jet in the specified kinematic region, while the expected
level of the inner hadronic bremsstrahlung (which is not included in the Monte
Carlo) is (0.340 +/- 0.001 +/- 0.038) x 10^{-3} gamma/jet. The ratio of the
excess to the predicted bremsstrahlung rate is then (3.4 +/- 0.2 +/- 0.8),
which is similar in strength to the anomalous soft photon signal observed in
fixed target experiments with hadronic beams.Comment: 37 pages, 9 figures, Accepted by Eur. Phys. J.
A Determination of the Centre-of-Mass Energy at LEP2 using Radiative 2-fermion Events
Using e+e- -> mu+mu-(gamma) and e+e- -> qqbar(gamma) events radiative to the
Z pole, DELPHI has determined the centre-of-mass energy, sqrt{s}, using energy
and momentum constraint methods. The results are expressed as deviations from
the nominal LEP centre-of-mass energy, measured using other techniques. The
results are found to be compatible with the LEP Energy Working Group estimates
for a combination of the 1997 to 2000 data sets.Comment: 20 pages, 6 figures, Accepted by Eur. Phys. J.
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