Search results for "METHODOLOGIE"
showing 10 items of 2141 documents
Half a Century of Experimental Photonuclear Physics
2001
Half a century of experimental nuclear physics is reviewed by looking at the evolution of some experiments, mostly starting with abstracts from APS meetings in 1950.
One-shot color digital holography based on the fractional talbot effect
2010
We present a simple method for recording on-axis color digital holograms in a single shot. Our system performs parallel phase-shifting interferometry by using the fractional Talbot effect for every chromatic channel simultaneously. Experimental results are also shown.
Ultra-low material pixel layers for the Mu3e experiment
2016
The upcoming Mu3e experiment will search for the charged lepton flavour violating decay of a muon at rest into three electrons. The maximal energy of the electrons is 53 MeV, hence a low material budget is a key performance requirement for the tracking detector. In this paper we summarize our approach to meet the requirement of about 0.1 % of a radiation length per pixel detector layer. This includes the choice of thinned active monolithic pixel sensors in HV-CMOS technology, ultra-thin flexible printed circuits, and helium gas cooling.
Software Timing Calibration of the ARGO-YBJ Detector
2009
The ARGO-YBJ experiment is mainly devoted to search for astronomical gamma sources. The arrival direction of air showers is reconstructed thanks to the times measured by the pixels of the detector. Therefore, the timing calibration of the detector pixels is crucial in order to get the best angular resolution and pointing accuracy. Because of the large number of pixels a hardware timing calibration is practically impossible. Therefore an off-line software calibration has been adopted. Here, the details of the procedure and the results are presented. (C) 2008 Elsevier B.V. All rights reserved.
A computer-assisted experiment to study the influence of the point spread function in the image formation process
2018
[EN] We present a new open experimental setup assisted with LabView to be used to teach the concept of the point spread function (PSF). The PSF describes the response of an image-forming system to a point object. The PSF concept is of fundamental importance in optics since the output of an image-forming system can be simulated as the convolution of the PSF with the input object. In this work, a new graphical user interface has been developed to obtain a real-time measure of the PSF and the corresponding images provided by different lenses and pupils with different sizes and shapes. From a didactical point of view, the proposed method allows students to interpret the results in a visual and …
On a Class of Feynman Integrals Evaluating to Iterated Integrals of Modular Forms
2019
In this talk we discuss a class of Feynman integrals, which can be expressed to all orders in the dimensional regularisation parameter as iterated integrals of modular forms. We review the mathematical prerequisites related to elliptic curves and modular forms. Feynman integrals, which evaluate to iterated integrals of modular forms go beyond the class of multiple polylogarithms. Nevertheless, we may bring for all examples considered the associated system of differential equations by a non-algebraic transformation to an \(\varepsilon \)-form, which makes a solution in terms of iterated integrals immediate.
Maximal slicings in spherical symmetry: Local existence and construction
2011
We show that any spherically symmetric spacetime locally admits a maximal spacelike slicing and we give a procedure allowing its construction. The construction procedure that we have designed is based on purely geometrical arguments and, in practice, leads to solve a decoupled system of first order quasi-linear partial differential equations. We have explicitly built up maximal foliations in Minkowski and Friedmann spacetimes. Our approach admits further generalizations and efficient computational implementation. As by product, we suggest some applications of our work in the task of calibrating Numerical Relativity complex codes, usually written in Cartesian coordinates.
Quantum search by parallel eigenvalue adiabatic passage
2008
We propose a strategy to achieve the Grover search algorithm by adiabatic passage in a very efficient way. An adiabatic process can be characterized by the instantaneous eigenvalues of the pertaining Hamiltonian, some of which form a gap. The key to the efficiency is based on the use of parallel eigenvalues. This allows us to obtain non-adiabatic losses which are exponentially small, independently of the number of items in the database in which the search is performed.
Measurement of the t-channel single top quark production cross section
2009
The D0 collaboration reports direct evidence for electroweak production of single top quarks through the t-channel exchange of a virtual W boson. This is the first analysis to isolate an individual single top quark production channel. We select events containing an isolated electron or muon, missing transverse energy, and two, three or four jets from 2.3 fb^-1 of ppbar collisions at the Fermilab Tevatron Collider. One or two of the jets are identified as containing a b hadron. We combine three multivariate techniques optimized for the t-channel process to measure the t- and s-channel cross sections simultaneously. We measure cross sections of 3.14 +0.94 -0.80 pb for the t-channel and 1.05 +…
Search for pair production of the scalar top quark in the electron-muon final state
2010
We report the result of a search for the pair production of the lightest supersymmetric partner of the top quark ($\tilde{t}_1$) in $p\bar{p}$ collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider corresponding to an integrated luminosity of 5.4 fb$^{-1}$. The scalar top quarks are assumed to decay into a $b$ quark, a charged lepton, and a scalar neutrino ($\tilde{\nu}$), and the search is performed in the electron plus muon final state. No significant excess of events above the standard model prediction is detected, and improved exclusion limits at the 95% C.L. are set in the the ($M_{\tilde{t}_1}$,$M_{\tilde{\nu}}$) mass plane.