Section de physique
Département de physique nucléaire et corpusculaire



Séminaires de physique corpusculaire

Les séminaires du DPNC ont lieu les mercredis à 17.00 heures (chaques deux semaines) dans l'auditoire Stückelberg, Ecole de physique, 24, quai Ernest-Ansermet, Genève.

Semestre d'Hiver 2003-2004

Journées du DPNC :


Semestre d'hiver 2003-2004

05 Nov. 2003 Dr T. Gys, CERN Introduction à la technologie des photodétecteurs hybrides à pixels et à leurs applications
09 Nov. 2003 Dr Lukas Tlustos The Medipix2 detector - performance, measurements and applications
03 Dec. 2003 Prof. Thierry Courvoisier La mission INTEGRAL et ses premiers résultats
17 Dec. 2003 Dr Alexander Sakharov Antimatter regions in the baryon-dominated Universe
28 Jan. 2004 Prof. K. Pretzl Direct detection of dark matter
17 Mar. 2004 Dr Mario Campanelli Beauty(ful) and Charm(ing) physics with CDF II
31 Mar. 2004 Prof. Matteo Cacciari Bottom Production vs. Theory: Past and Present
21 Apr. 2004 Dr Roland Horisberger Development of a Pixel Vertex Detector for the CMS experiment at LHC
19 May 2004 Prof. Günther Dissertori Issues in Standard Model and Higgs Physics, as seen by an experimentalist from CMS
02 June 2004 Prof. André Rubbia The liquid Argon Time Projection Chamber : a new, mature technology for the detection and imaging of rare events
16 June 2004 Pr. J. Schukraft Heavy Ion Physics with the ALICE detector at the CERN LHC


Prof. T. Gys, CERN - Introduction à la technologie des photodétecteurs hybrides à pixels et à leurs applications

Les photo-détecteurs hybrides à pixels combinent dans un seul dispositif la technologie des tubes photo-détecteurs à vide et celle de la micro-électronique. Leur principe est le suivant : un photo-électron, issu de la conversion d'un photon dans une photo-cathode, est accéléré par une haute tension de l'ordre de 20kV vers une matrice de pixels au silicium. Cette énergie cinétique est dissipée près de la surface du silicium et donne lieu à la création de quelque 5000 paires électrons-trous. Cette charge est détectée par une électronique binaire spécifique intégrée dans le dispositif.

Le séminaire couvre les principes opératoires, les aspects technologiques et les domaines d'applications potentiels des photo-détecteurs hybrides à pixels. Des exemples spécifiques, plus particulièrement en physique des hautes énergies et accessoirement en comptage de photons et imagerie beta et gamma, seront présentés. .pdf


Dr. Lukas Tlustos - CERN ETT/TT -The Medipix2 detector - performance, measurements and applications

The Medipix2 chip comprises a matrix of 256 x 256 identical readout channels which operate in single photon-counting mode when connected to an appropriate detector with identical pixel size. As the interconnect between readout chip and detector is based on fine pitch bump bonding it can be connected to different detector substrates leaving free the possibility to investigate novel detector materials. The chip was developed at CERN within the framework of the Medipix collaboration and is based on pixel detector developments for High Energy Physics. It provides at the same time high spatial resolution (55um pixel pitch), high count rate, high signal-to-noise ratio and noise discrimination using 2 discriminators per pixel. Due to its excellent imaging performance the Medipix2 is used in a broad variety of applications, ranging from medical imaging to material analysis and dynamic defectoscopy. Recent performance measurements as well as examples for applications will be presented.


Dr Thierry J.-L. Courvoisier - INTEGRAL Science Data Centre - La mission INTEGRAL et ses premiers résultats

Le satellite d'observation du ciel dans le rayonnement gamma INTEGRAL a été développé par l'agence spatiale européenne (ESA) depuis 1989. Il a été lancé par une fusée russe de Baikonour le 17 octobre 2002. Le domaine d'énergie couvert par INTEGRAL s'étend de quelques keV à environ 10 MeV. Les instruments de mesures sont dotés de masques codes afin de fournir une résolution angulaire de quelques minutes d'arc. Une résolution spectrale de 500 est obtenue grâce à des détecteurs de Germanium refroidis. Les premiers résultats de la mission incluent des mesures de sources galactiques et extra-galactiques. Des sources très absorbées ont été découvertes par INTEGRAL. Ces sources n'émettent que très peu de rayonnement X. Elles étaient jusque là inconnues. .pdf


Dr Alexander Sakharov - Division TH, CERN - Antimatter regions in the baryon-dominated Universe

A minor contribution of antimatter regions, which might be left from baryogenesis, can evolve into condensed antimatter objects; these are important footprints of early phase transitions, which took place far above electroveak energies. In particular quantum fluctuations of a complex, baryonic charged scalar field caused by inflation can generate large domains, which convert later into antimatter regions. As a result the Universe can become globally matter-dominated, with minor contribution of antimatter regions. The distribution and evolution of such antimatter regions could cause every galaxy to be a harbor of an anti-star globular cluster. The existence of one of such antistar globular cluster in our Galaxy does not contradict the observed $\gamma$-ray background, but the expected fluxes of $\bar{\rm ^4He}$ and $\bar{\rm ^3He}$ from such an antimatter object are definitely accessible to the sensitivity of the coming AMS-02 experiment. .pdf


Prof. Klaus Pretzl - Laboratory of High Energy Physics - University of Bern - Direct detection of dark matter

Only a very small fraction of the total mass in the Universe is made from visible matter. The nature of most of the invisible matter is still unknown. The latest developments in the search for the dark matter in the Universe and its direct detection will be discussed. .pdf


Dr Mario Campanelli - DPNC, University of Geneva - Beauty(ful) and Charm(ing) physics with CDF II"

The Run II of the Tevatron has started since more than two years, and the detectors have collected more than twice the integrated luminosity of run I. Although not sufficient for Higgs discovery, these data have allowed considerably improvements over the Run I measurements, especially in the fields where the detector upgrades have played a mayor role. In particular, low-Pt physics profits from the new SVT trigger, able to reconstruct on-line tracks with production of beauty and charm, and collect heavy flavor samples comparable to those of the b factories. I will present recent results and perspective for the future, with some emphasis on B_s mixing. .ppt


Prof. Matteo Cacciari - LPTHE, Univ. Paris 6 - Bottom Production vs. Theory: Past and Present

Bottom production as long been one of the very few instances where data and Standard Model predictions are apparently at variance. We review the comparisons performed in the past, up to the most recent ones, in gamma-gamma collisions, photoproduction and hadroproduction. In the light of the now fairly comfortable agreement observed in proton-antiproton
collisions, we discuss what improvements in both theory and data have brought about this change. .pdf


Dr Roland Horisberger - PSI - Development of a Pixel Vertex Detector for the CMS experiment at LHC

The CMS pixel detector is the innermost part of the charged particle tracking system of the Compact Muon Solenoid experiment at the Large Hadron Collider (LHC). Due to the small radius it is required to operate under very high track fluence rates. For the high luminosity operation of the LHC accelerator the pixel vertex detector has to be able to measure precisely all charged particle tracks at a rate of ~ 3 x 107 Hz/cm2 and without any significant data loss. These experimental conditions are many orders of magnitude beyond what previous experiments had to achieve in the past. The talk describes the concepts and the highly specialized R&D activities that were needed to develop the basic components for such a performing precision tracking detector. .pdf


Prof. Günther Dissertori - ETH Zürich - Issues in Standard Model and Higgs Physics, as seen by an experimentalist from CMS

After a brief review of the status of the CMS construction I will address issues related to Standard Model (SM) physics and searches for Higgs bosons with CMS at LHC. In particular I will try to point out which measurements and searches are dominated by systematic uncertainties and where we see a need for further theoretical input and/or improved experimental methods. .pdf


Professeur André Rubbia - ETH - Zurich - The liquid Argon Time Projection Chamber : a new, mature technology for the detection and imaging of rare events

After several years of R&D, the liquid Argon Time Projection Chamber (TPC) technique has reached maturity. The ICARUS experiment, which acts as a sort of observatory for the study of neutrinos and the instability of matter, is starting to come together. In the summer of 2001, the first module of the ICARUS T600 detector passed brillantly a series of tests. The year 2004 should see the detector's installation at the Underground Gran Sasso Laboratory and first data-taking should follow soon after. In this seminar, I will attempt to describe this new technology, overview the ICARUS physics programme at the Gran Sasso and discuss possible future mid and long term applications in new-generation experiments for matter instability searches, CP-violation in neutrino physics and dark matter searches. .pdf


Professeur Jurgen. Schukraft - CERN - Heavy Ion Physics with the ALICE detector at the CERN LHC

In 2007, the Large Hadron Collider at CERN is scheduled to start operation with proton beams (cms energy 14 TeV) and heavy ion beams (Pb at 5.5 TeV/nucleon). After a brief reminder of the motivation and goals of heavy ion physics, the talk will give a summary of the heavy ion program at the LHC, in particular pointing out topics which are complementary to the current RHIC program, and descibe in some detail the aims and status of the dedicated heavy ion experiment ALICE. .ppt


Last updated: 9 mars 2010, Blanchard Catherine