Section de physique Département de physique nucléaire et corpusculaire

Semestre d'Été 2005

The BooNE experiment sets out to definitively explore the neutrino oscillation signal reported by the Los Alamos LSND experiment. MiniBooNE represents the first phase for the BooNE collaboration and consists of a 1 GeV neutrino beam and a single, 800-ton mineral oil detector (the MiniBooNE detector). The MiniBooNE detector is located 500 meters downstream of the neutrino source, and is optimized to search for the LSND signal.

In 1995, the LSND collaboration presented strong evidence for the oscillation of muon anti-neutrinos to electron anti-neutrinos. These results lead to mass-squared differences around 1 eV^(2) - much larger than those observed by atmospheric and solar neutrino experiments.

The LSND measurement remains to be confirmed. If BooNE confirms this signal, then significant changes are demanded of our current model for understanding the building blocks of nature. In particular, a BooNE oscillation result will tell us that nature contains at least four different types of neutrinos, at least one of which would be almost totally non-interacting (or sterile).

Prof. Paul TIPTON, University of Rochester (New-York) - Looking for new physics around the Top

In Run 1 of Fermilab's Tevatron p-pbar collider, a slight excess of dilepton top candidates were observed. In addition some of these events had kinematic features that were not expected in Standard Model (SM) top decays. Using Run II data from the upgraded CDF detector, we have examined a larger sample of dilepton events for evidence of non-SM physics. Among the studies is an a priori defined search for anomalous kinematics.

Prof. Oliver Bruning, CERN - Accelerator Physics Challenges for the Large Hadron Collider at CERN

The Large Hadron Collider project at CERN will bring the energy frontier of high energy particle physics back to Europe and with it push the accelerator technology into uncharted teritory. The talk presents the LHC project in the context of the past CERN accelerator developments and addresses the main challenges in terms of technology and accelerator physics. .pdf

Prof. Ulrich Straumann, Université de Zurich - Status and prospects of the LHCb experiment

The LHCb experiment is designed to exploit the large b quark production cross section in pp collisions at the future LHC at CERN in order to perform a wide range of precision studies of CP violating phenomena and rare decays in the B meson systems. The experiment will operate at a moderate luminosity of 2Ã^×1032 cm-2s-1 and should be fully operational from the start of LHC operation in mid of 2007. An overview of the design and present production status of the experiment will be given, with some emphasis on the silicon tracking system, provided by the Swiss groups. The physics reach of the experiment will be demonstrated by the results of some Monte Carlo simulations.

Prof. Edoardo Charbon, EPFL - CMOS Single Photon Detectors

With the integration of Single Photon Avalanche Diodes (SPADs) in conventional CMOS technology, the design of scalable single photon imagers has become possible. SPAD pixels exhibit high sensitivity, dynamic range and low jitter, thus enabling new as well as conventional applications. Moreover, due to the digital nature of SPAD detectors, the imager architecture may be significantly simplified with the elimination of traditional components such as amplifiers, S/Hs, and ADCs as well as complex readout schemes and 1/f or FPN suppression techniques.

As an illustration of the potential of SPADs, a 3D imager is presented capable of capturing the depth map of an arbitrary scene. Depth is measured by computing the time-of-flight of a ray of light as it leaves the source and is reflected by the objects in the scene. The round-trip time is converted to digital code independently for each pixel using a CMOS time-to-digital converter. To reach millimetric accuracies an array of 32x32 SPADs is used. The scene is illuminated using a cone of low power pulsed laser light, thus no mechanical scanning devices or expensive optical equipment are required. .pdf

Prof. Alexandre Refregier, CEA, Saclay - Weak lensing et énergie sombre

L'effet de cisaillement gravitationnel faible, ou "weak lensing", permet de cartographier directement la distribution de la matière sombre dans l'univers. Cette distribution peut être comparée aux prédictions des modèles de formation des structures afin de contraindre les paramètres cosmologiques. Après un rappel des principes du weak lensing, je résumerai le statut observationnel de ce domaine en évolution très rapide. Je présenterai ensuite les perspectives offertes par les futurs relèves grands champs. En particulier, je montrerai comment ces nouvelles mesures du weak lensing par les grandes structures permettront de placer des contraintes fortes sur l'énergie sombre, en complément d'autres sondes telles que le CMB et les supernovae. Je montrerai enfin les perspectives offertes par DUNE, une future mission spatiale grands champs, pour la cosmologie.

Prof. Michele Maggiore, Université de Genève - The search for gravitational waves. Physical motivations and experimental perspectives

Professor Maggiore will give an overview of gravitational-wave physics, addressing two main questions:
1) What are the physical motivations for gravitational-wave research, both from the point of view of astrophysics and of high-energy physics.
2) Present staus and future perspectives of gravitational-wave experiments.

Prof. Jean-Pierre Lees, LAPP, Annecy - Recent results of the BaBar experiment on CP Violation in the B mesons decays

After a brief introduction on B physics at B factories and the current status of the BaBar experiment, I will show how CP violation effects in the decays B->D(*)K(*) and B->D(*)pi/rho can be used to probe the value of the angle gamma of the Unitarity triangle, and what precision can be expected on this measurement by the end of the BaBar running, in 2008.

Semestre d'hiver 2004-2005

A review of the current experimental situation will be given with emphasis on recent results obtained at CERN. The speaker will argue that the availability of high energy kaon beams at CERN allows one to make incisive tests of the Standard Model. In particular the NA48 Collaboration has studied the possibility to measure the reaction K+-->pi+ nu nubar leading to a ~10% precision on the knowledge of the |Vtd| CKM parameter. Prospects to study of the CP-Violating decays KL--> pi0 e+e- (mu+mu-) and KL--> pi0 nu nubar will also be briefly described.

Prof. Jean-Pierre Delahaye, CERN - The CLIC study of Multi-TeV e⁺/e^- Linear Collider

After a brief description of a CLIC scheme to extend Linear Colliders into the Multi-TeV colliding beam energy range, the main challenges and the very promising results already achieved will be presented. The presentation will mainly focus on the Test Facility (CTF3) presently under construction at CERN within a broad collaboration to address the main key issues and demonstrate the feasibility of the CLIC technology before 2010. .pdf

Prof. Zbigniew Was, Institute of Nuclear Physics, Cracow, Poland - Tau leptons as window for new physics at accelerator experiments

Because of its mass and relative clean experimental signature, the tau lepton is expected to play an important role in the phenomenology of future experiments. We will present the use of observables using taus for the following applications. Higgs boson parity measurement at ILC, signatures for Higgs discovery scenarios at LHC and for the measurement of CP properties of scalar B⁰ decay to tau tau (if discovered) at Belle/BaBar. This wide spectrum of experimental applications will be complemented with a presentation of the essential theoretical and technical aspects of these projects.

Last updated: 9 mars 2010, Blanchard Catherine