S?minaire de physique corpusculaire

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Le s?minaire de DPNC tient lieu le mercredi a 17.00 heures (chaques deux semaines) dans l'auditoire St?ckelberg

 Semestre d'Hiver 1999-2000 - Semestre d'Ete 2000

Seminaire d' annee 1998-1999S?minaire des ann?es pr?c?dentes

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Semestre d' ete 1999-2000

15 Mar 2000 Prof. A. Litke
University of California, Santa-Cruz
What Does the Eye Tell the Brain?: 
A High Energy Physicist Enters the World of Neurobiology" 
29 Mar 2000 Prof. Fyodor Tkachov 
INR RAS, Moscow
A Systematic Theory of Jet Definition
Canceled 12 Avril 200 Dr. Szymon Gadomski
CERN- EP Division
Measurement of the b-quark Fragmentation Fractions in p-pbar Collisions at sqrt(s) = 1.8 TeV
3 Mai 2000 Dr. Alessandra Filippi
INFN, Torino
Experimental Results on Strangeness Production in Nucleon-Antinucleon Annihilation
10 Mai 2000 Dr. Szymon Gadomski
CERN- EP Division
Measurement of the b-quark Fragmentation Fractions in p-pbar Collisions at sqrt(s) = 1.8 TeV
17 Mai 2000 Y. Karyotakis
LAPP, Annecy
L'Experience BaBar, Mesure de la Violation de CP
31 Mai 2000 Prof. Andre Rubbia
ETH, Zurich
Status of the ICANOE Project

Prof. Alan Litke, University of California Santa Cruz: What Does the Eye Tell the Brain?: A High Energy Physicist Enters the World of Neurobiology."

After a brief introduction to vision, I will describe a system we are developing to study how the retina processes and encodes visual images. The "Retinal Readout System" will allow the simultaneous detection of signals from hundreds of output neurons in a living retina as it responds to a dynamic visual image focused on the input neurons. The correspondence between these output signals and the visual stimulus will help us understand the code that the eye uses to send information about the visual world to the brain. This system will be based, in part, on the silicon microstrip detector technology and expertise developed for the study of short-lived particles in high energy physics experiments.

Prof. Fyodor Tkachov: A Systematic Theory of Jet Definition

The talk is an overview of the systematic theory of jet definition developed recently (hep-ph/9901444, revision Jan. 2000) from first principles of physical measurements and QCD. The resulting jet definitions are naturally interpreted as cone algorithms with dynamically determined cone shapes and entirely based on shape observables that generalize the venerable thrust, thus being superbly ameanable to theoretical studies. Furthermore, the proposed algorithms solve the fundamental problem with the conventional algorithms (i.e. a vicious circle in the definition due to a lack of principles to fix initial cone configuration/recombination order). A fast and robust fortran code is available from http://www.inr.ac.ru/~ftkachov/projects/jets/index.htm. The theory offers new options: a model independent tool for a quantitative description of hadronization effects and the option of multiple jet configurations (which physically corresponds to non-uniqueness of inversion of hadronization).

Dr. Szymon Gadomski, CERN-EP Division: Measurement of the b-quark fragmentation fractions in p-pbar collisions at sqrt(s) = 1.8 TeV

The CDF experiment has measured the probability of b quark to form B0s, B0d or B+. This probabilities, known as the fragmentation fractions, have not been measured in hadron collisions before. The measurement is also interesting because of the new technique of reconstructing B mesons - using sequential di-muon decays. The talk will present a brief overview of the technique and the obtained result.

Dr. Alessandra Filippi, INFN Torino: Experimental Results on Strangeness Production in Nucleon-Antinucleon Annihilation

The latest generation of LEAR Experiments has provided a wealth of high statistics data for the study of open and hidden strangeness production in antinucleon-nucleon annihilation at rest and in flight a low momenta. Many observations, performed in several final states and in different  experimental conditions, have shown the presence of anomalous effects which cannot be accounted for by the simple naive Quark Model; among them, an abundant production of phi meson evident in many  annihilation channels, which implies a dramatic OZI rule violation. For a more satisfactory interpretation of the observed effects the  formulation of new models is required. One of the most appealing suggests the presence in the nucleon wave function of a negatively strange quark condensate, whose effects could be significant even at low energies. A review of the latest experimental results from LEAR by will be reported,
and their possible interpretation in the frame of some recently proposed models will be discussed.

Dr. Yannis Karyotakis, LAPP Annecy: L'experience BaBar, Mesure de la Violation de CP

BaBar is running since a year now and has collected more than 7 fm^-1 of data. The detector status and performances will be presented together with preliminary analyses results, showing the capability of the experiment to measure reliably sin(2 beta) in the very near future. Plans for further CP measurements will be discussed and compared with expectations of other experiments.

Prof. Andre Rubbia, ETH Zurich: Status of the ICANOE Project


Semestre d' hiver 1999-2000

24 Nov 1999 Dr. Lydia Iconomidou-Fayard 
La mesure de la Violation Directe de CP avec l'experience NA48 au CERN
8 Dec 1999 Dr. Giovanni. Ambrosi 
University of Geneva
Search for anti-matter and geomagnetic effects on trapped particles with the AMS-01 detector
12 Jan 2000 Dr. Nikos Konstantinidis
University of California, Santa-Cruz
LEP up to 202 GeV - Anything new?
19 Jan 2000 Prof. John Carr
Universite d' Aix - Marceille II
Status of the ANTARES experiment
2 Fev 2000 Dr. Yannis Karyotakis
LAPP Annecy
Canceled - Annule
9 Fev 2000 Prof. Geoffrey Taylor
University of Melbourne
Recent developments of the BELLE experiment at KEK
16 Fev 2000  Dr. Manel Martinez
IFAE-Universitat Autonoma de Barcelona
Gamma ray astronomy with the MAGIC telescope


Dr. Lydia Fayard, LAL-Orsay: La mesure de la Violation Directre de CP avec l' Experience NA48 au CERN

L'experience NA48 a annonce en Juin dernier son premier resultat concernant la mesure de Re(epsilon'/epsilon). Lors de ce seminaire nous parlerons des aspects experimentaux de NA48 ainsi que de l'analyse qui a conduit a cette mesure.

Dr. G. Ambrossi, University of Geneva: Search for anti-matter and geomagnetic effects on trapped particles with the AMS-01 detector

The AMS experiment is a magnetic spectrometer designed and constructed to measure charged particles in space. The detector used a permanent magnet together with a precision silicon tracking detector, time-of-flight counters and areogel counters. The first 10-day mission of AMS took place on June 2, 1998 on board the NASA space Shuttle Discovery. The construction of the AMS detector, results on the anti-matter search and geomagnetic effects on trapped particles will be presented.

Dr. Nikos Konstantinidis, University of California Santa-Cruz: LEP up to 202 GeV - Anything new?

At the end of a very successful year, the four LEP experiments presented last November the results from a first look at the data up to 202GeV. I will review their findings, focussing on the issues left to be clarified (with an "insider's" view for some of them), and discuss the implications for HEP and the future prospects.

Prof. Jhon Carr, CPPM Marceille: ANTARES: An Undersea Neutrino Telescope

The ANTARES Collaboration is in the process of building an Undersea Neutrino Telescope in the Mediteranean Sea 40km offshore from Toulon, France. The first R&D phase of the project is now finished and the construction of a 0.1km2 surface area detector is started. The talk will report on results from the site measurements of the first phase of the program and discuss the scientific and technical aims of the second phase. The ultimate aims of ANTARES are exploration of the universe using the new "messanger" of neutrinos compared to the traditional messanger of photons of different wavelengths. Indirect searchs of dark matter in the form of relic neutralinos trapped in massive bodies will be possible with the same detector, as will measurements of oscillations of atmospheric neutrinos.

Prof. Geoffrey Taylor, Melbourne: BELLE - a search for CP violation in B-meson decays

Symmetries of nature have successfully guided our understanding of the constituents of matter and their interactions. The symmetry between particles and anti-particles is described by the CP invariance of their interaction. CP invariance is known to be a very good symmetry of nature but not a perfect one. CP violation, first seen in the decays of neutral K-mesons in the early sixties, has only been seen in that process. An understanding of the dominance of matter over anti-matter in our universe demands a more significant violation of this symmetry than is seen in the Kaon system. In the standard model of particle physics large CP violation is expected in B-meson decays. This talk will give an overview and status of one of the major efforts to discover and precisely measure CP violation in B-mesons. The BELLE experiment at the Japanese KEK laboratory's KEKB colliding beam was commissioned in 1999. This talk will describe the experiment and give a progress report on its commissioning.

Dr. Manel Martinez, IFAE - Universitat Autonoma de Barcelona: Gamma ray astronomy with the MAGIC telescope

MAGIC, which stands for a "Major Atmospheric Gamma Imaging Cherenkov" is a telescope which will see its first light in summer 2001 in the "Roque de los
Muchachos" observatory in the "La Palma" Canary Island. The main aim of this project is opening an unexplored window in Gamma Ray Astronomy. The present status of this field as well as the physics motivation for MAGIC, its observational principles and its main technical challenges will be discussed.

Last updated: 25  November 1999, Ilias Efthymiopoulos