Séminaires de physique corpusculaire
Semestre de Printemps 2013
|Date||Conférencier||Titre du séminaire et Annonce|
|Prof. Laura Baudis
University of Zurich
|Dark matter searches with liquid xenon|
|27 Fev.||Dr Saverio Braccini
University of Bern
|The new Bern cyclotron laboratory for PET radioisotope production and its beam line for multi-disciplinary research|
|20 Mar.||Dr Vittorio Boccone
Université de Genève
|A new technique in gamma astronomy: an innovative camera for a high-energy gamma-ray telescope array|
|24 Avr.||Dr Roberto Cardarelli
University Tor Vergata
|Ultra low-noise amplifiers for silicon and diamond detectors|
|08 Mai||Dr Francesco Cafagna
Bari University & INFN
|The PAMELA mission: more than six years of Cosmic Rays investigation|
|15 Mai||Dr Jiri Krepel
PSI Paul Scherrer Institut
|Thorium or Uranium fuel cycle for advanced
Fuel recycling, multi-recycling, breeding and burning
|29 Mai||Dr Mercedes Paniccia
Université de Genève
|AMS - First results|
Feb 06: Prof. Laura Baudis, University of Zurich
Title: Dark matter searches with liquid xenon - Access to the talk
Abstract: We have strong evidence that about 80% of matter in our Universe is dark, revealing its presence only by its gravitational attraction. If the dark matter is made of Weakly Interacting Massive Particles (WIMPs), it can be directly detected via elastic scattering from nuclei in ultra-low background, deep underground detectors. After a brief introduction to the direct detection method, I will review current techniques based on liquid xenon as target material to search for these hypothetical particles. The focus will be on recent results, including those of XENON100, and on the most promising ideas for the near future.
Feb 27: Dr Saverio Braccini, Albert Einstein Center for Fundamental
Physics, University of Bern
Title: The new Bern cyclotron laboratory for PET radioisotope production and its beam line for multi-disciplinary research - Access to the talk
Abstract: The new Bern cyclotron laboratory is based on a 18 MeV proton cyclotron equipped with a specifically conceived 6 m long research beam line, terminated in a separate bunker. This particular configuration is designed for industrial Positron Emission Tomography (PET) radioisotope production as well as for novel detector, radiation biophysics, radiation protection, materials science, radiochemistry and radiopharmacy scientific activities. This project is the result of the successful collaboration among the University Hospital in Bern (Inselspital), the University of Bern, private investors and industrial partners. This new facility is now operational and open to national and international collaborations. The design, the construction, the commissioning and the first research activities will be presented.
Mar 20: Dr Vittorio Boccone, University of Geneva
Title: A new technique in gamma astronomy: an innovative camera for a high-energy gamma-ray telescope array - Access to the talk
Abstract: Solid-state detectors, in particular Geiger-mode Avalanche Photo-Diodes (G-APDs) represent a valuable alternative to substitute the Photomultipliers in many applications.
The Cherenkov Telescope Array (CTA) is the first open-access high energy (HE) gamma ray observatory and consists of many tens of telescopes of three different sizes (Small, Medium and Large) covering a large area on the ground.
We proposed a novel design for the Small Size Telescopes of CTA based on a 4 m Davies Cotton reflector focusing the light on a large area G-APD (developed by us together with Hamamatsu) array coupled to non-imaging light concentrators.
I’ll first introduce briefly the physics motivations of CTA with particular regards to the SST energy range and I’ll then give an overview of the 4-m DC SST project. I will focus my talk on the R&D necessary for the design and construction of the G-APD camera that was proposed by the University of Geneva. I will describe the measurements necessary to characterize the G-APD and I will discuss and compare our first results to the design requirements.
April 24: Dr Roberto Cardarelli, University Tor Vergata
Title: Ultra low-noise amplifiers for silicon and diamond detectors - Access to the talk
Abstract: Thanks to the SiGe heterojunction, in the last years the BJT transistor technology has been experiencing a great development for high frequency and low-noise operation. The performance of an ultra-low-noise preamplifier (500 e- RMS) with low frequency (100 MHz BW) will be shown. This amplifier, given the low dependence of the noise from the source capacitance (up to 1 nF), the very fast rise time (up to 100 ps) and the 50 Ohm input impedance, is particularly promising for silicon, diamond and high rate gas detectors.
May 08: Dr Francesco Cafagna, Bari University and INFN
Title: The PAMELA mission: more than six years of Cosmic Rays investigation - Access to the talk
Abstract: The PAMELA mission major scientific objective is the measurements of Cosmic Rays energy spectra, with special focus on the antiparticles, i.e. antiprotons and positrons, ones.
The PAMELA apparatus is a satellite borne magnetic spectrometer and comprises a time-of-flight system, a silicon-microstrip magnetic spectrometer, a silicon-tungsten electromagnetic calorimeter, an anticoincidence system, and shower tail catcher scintillator. It has been more than six years that the PAMELA mission is taking data in space, on board of the russian satellite Resurs-DK.
Important results have been obtained on the positron and antiproton abundance and spectra. Moreover new results have been obtained on the composition of the charged cosmic radiation that challenge our current understanding of the mechanisms of production, acceleration and propagation of cosmic rays in the Galaxy.
In this talk we will review the most recent scientific results obtained by PAMELA and the apparatus performances during its six year mission.
May 15: Dr Jiri Krepel, PSI Paul Scherrer Institut
Title: Thorium or Uranium fuel cycle for advanced nuclear reactors? Fuel recycling, multi-recycling, breeding and burning. - Access to the talk
Abstract: Thorium fuel cycle provides several advantages, which make it very attractive; e.g. lower waste production and possibly improved reactor safety. However, there are also some drawbacks if compared with Uranium cycle. The seminar will provide an overview of basic physical features of both Thorium and Uranium fuel cycles and comparison of their performance (criticality, breeding gain) and safety-related (Doppler effect, coolant density effect) parameters, with respect to the fuel recycling, multi-recycling, breeding and burning.
May 29: Dr Mercedes Paniccia, University of Geneva
Title: AMS - First results
Precision measurement of the positron fraction in primary cosmic rays from 0.5 to 350 GeV with AMS02
The Alpha Magnetic Spectrometer is a state-of-the-art particle physics detector operating as an external module on the International Space Station. It uses the unique environment of space to study the universe and its origin by searching for antimatter, dark matter while performing precision measurements of cosmic rays composition and flux. Since its installation on May 19, 2011 it has collected over 30 billion cosmic rays of energies ranging from several hundred MeV up to few TeV.
In this talk we will present the precision measurement of the positron fraction in cosmic rays in the energy range from 0.5 to 350 GeV based on 6.8 million positron and electron events collected in the initial 18 month period of operation in space.
|Date||Conférencier||Titre du séminaire et Annonce|
|19 Sep.||Dr Philipp Mertsch
University of Oxford & University of Stanford
|From radio halos to Fermi bubbles|
|26 Sep.||Dr Bill Murray
Rutherford Appleton Laboratory (RAL)
|Higgs Boson properties and how to constrain them|
||Prof. Subir Sarkar
University of Oxford
|Alternative to SUSY dark matter|
||Prof. Andrii Neronov, ISDC, Université de Genève||Gamma-ray astronomy in the 100 TeV band|
|07 Nov.||Dr Mario Campanelli
|Jet substructure as a tool to reconstruct the decay of heavy boosted objects|
|21 Nov.||Prof. Alain Blondel
Université de Genève
|Future possibilities for precise studies of the H(126) Higgs candidate|
|05 Dec.||Prof. Max Klein
University of Liverpool
|Physics and Realisation of the LHeC|
|12 Dec.||Dr Daniel Muenstermann
|Radiation-hard Active Silicon Sensors for the ATLAS Upgrade|
|19 Dec.||Prof. Julien Lesgourges
|Active and Sterile Neutrinos in Cosmologie|
Sept. 19: Dr Philipp Mertsch, University of Oxford and Kavli Fellow
at the Kavli Institute of Particle Astrophysics and Cosmology, SLAC,
Title: From radio halos to Fermi bubbles
Diffuse radiation fields pervade the Galaxy from radio waves to gamma-rays and encode a plenitude of information about non-thermal processes. For other studies, e.g. dark matter searches, CMB analysis or even for faint point sources, they constitute an irreducible background and need to be subtracted off. I will focus on diffuse Galactic emission in the radio and in gamma-rays describing new ways to understand and model them. Particular mention will be made of the recently detected Fermi bubbles and I will suggest a theoretical picture that can explain both their energy spectrum and morphology.
26: Dr. Bill Murray (RAL):
Title: Higgs boson properties and how to constrain them -Access to the talk
Abstract: The recently-discovered new boson at CERN seems to be a good candidate for the long-sought Higgs boson. This seminar explores what we need to learn about it to confirm that it is the Higgs boson and how we will obtain that information. Some progress should come rather rapidly at the LHC, but other information will be much harder. If it is the Higgs boson then its existence at this mass presents some interesting puzzles, and more detailed measurements may tell us something about the dark matter binding galaxies together and maybe the ultimate fate of the Universe.
8: Prof. Subir Sarkar (Oxford)
Title: Alternatives to SUSY dark matter - Access to the talk
Abstract: Much effort has been devoted to the study of weak scale particles, e.g. supersymmeteric neutralinos, which have a relic abundance from thermal equilibrium in the early universe of order what is inferred for dark matter. This does not however provide any connection to the comparable abundance of baryonic matter, which *must* have a non-thermal origin. Candidate particles with such a connection are "dark baryons" with mass of order 10 GeV from a new strongly
interacting sector. Putative signals in experiments such as CoGeNT, CRESST and DAMA have also focussed attention on such particles. They can affect heat transport in the Solar interior so as to affect low energy neutrino fluxes and helio-seismology.
31: Prof. Andrii Neronov (ISDC, University of Geneva)
Title: Gamma-ray astronomy in the 100 TeV band
Abstract: Small size telescopes (SST) sub-array of the next-generation ground-based gamma-ray observatory CTA will extend the energy "window" available for astronomical observations toward the 100 TeV energy band. Based on the experience of observations with the current-generation gamma-ray telescopes, HESS, MAGIC and VERITAS, we have some idea of what kinds of astronomical sources and what kinds of astrophysical phenomena we will observe in this new "extremely high energy" (EHE) band. However, future observations of the sky in the up-to-now unexplored EHE gamma-ray band might bring some surprising unexpected discoveries. In this talk I will review the perspectives and challenges of the new field of EHE gamma-ray astronomy which will be opened by the SST sub-array of CTA.
Nov. 7: Dr. Mario Campanelli (UCL)
Title: Jet substructure as a tool to reconstruct the decay of heavy boosted objects - Access to the talk
Abstract: The LHC is the first collider where particles with mass at the electroweak scale can be produced with momenta much higher than their mass. The decay products of these particles are very boosted, and Hadronic decays would be reconstructed as a single "fat" jet. In the last few years there has been a great wealth of studies in the field of hadronic jet substructure to reconstruct these final states. In this seminar i will review the main phenomenological ideas, as well as the first experimental results using jet substructure as a tool to explore new and old physics.
21: Prof. Alain Blondel, Université de Genève
Title: Future possibilities for precise studies of the H(126) Higgs candidate - Access to the talk
Abstrac: We present a summary of the state-of-the-art comparison relevant to possible studies of the H(126) Higgs boson candidate. The machines considered are the LHC and its upgrades, Linear and circular e+e- colliders such as ILC/CLIC or LEP3/TLEP, gamma-gamma colliders and muon colliders. The conclusions of the recent ICFA beam dynamics HF2012 workshop in Fermilab will also be shown.
5: Prof. Max Klein, University of Liverpool
Title: Physics and Realisation of the LHeC - Access to the talk
Abstract: The Large Hadron Electron Collider (LHeC) project involves upgrading the LHC with a new electron beam in order to build a luminous, TeV energy ep and eA collider at CERN. An introduction is given to the physics programme of the LHeC, and the design concepts are described of the 60 GeV electron accelerator and of a new detector for precision deep inelastic scattering.
12: Dr Daniel Muenstermann, CERN
Title: Radiation-hard Active Silicon Sensors for the ATLAS Upgrade
Abstract: In the coming years, the LHC will be upgraded to provide much higher luminosity. This implies increased radiation damage, occupany and pile-up for ATLAS and requires the replacement of the current Inner Detector with an improved all-silicon Tracker. While the standard silicon sensor technology appears to be capable of fulfilling the demanding HL-LHC requirements, new innovative technologies might offer significant advantages.
Deep-submicron HV CMOS processes feature moderate bulk resistivity and HV capability and are therefore good candidates for drift-based radiation-hard monolithic active pixel sensors (MAPS). For the ATLAS Upgrade, the concept of using a deep-submicron HV CMOS process to produce a drop-in replacement for traditional radiation-hard silicon sensors is explored. Unlike fully integrated MAPS, such active sensors contain simple circuits, e.g. amplifiers and discriminators, but still require a traditional (pixel or strip) readout chip. This approach yields most of the advantages of MAPS (improved resolution, reduced cost and material budget, etc.), without the complication of full integration on a single chip.
After outlining the design of the HV2FEI4 test ASIC, characterization results and first experience obtained with pixel and strip readout will be shown before discussing future prospects of active sensors and CMOS-based detectors in general.
19: Prof. Julien Lesgourges, EPFL, Lausanne
Title: Active and sterile neutrinos in cosmology - Access to the talk
Abstract: Review of status and prospects for constraining the neutrino sector using cosmological observables, with an emphasis on cosmic microwave background and large scale structure data.
exceptionnels - Candidats au poste de MER
Mercredi 18 juillet 2012 dès 08h30 - Auditoire Stückelberg
Ecole de physique, 24, quai Ernest-Ansermet, Genève
08h30-09h20 :Dr Chiara Casella (ETZH)
- From muon lifetime to positron emission tomography: Scintillators
and photodetectors in precision measurements
The detection of scintillation light produced by ionizing radiation is certainly one of the oldest and still most widely adopted techniques in particle physics. Based on my personal experience, I will describe the experimental concepts and results of two different examples in this direction: the FAST and the AX-PET experiments.
FAST is a high precision muon lifetime measurement, aiming at a 2 ppm accuracy on the muon lifetime tµ. This is achieved with a DC p+ beam (170 MeV/c), stopped on a high granularity plastic scintillator target, viewed by position sensitive photomultipliers (PSPM).
AXPET is a prototype for a novel geometrical concept of positron emission tomography (PET), based on matrices of LYSO scintillating crystals read-out by Silicon Photomultipliers (SiPM), for the detection of 511 keV photons. It aims at a high spatial resolution (~ 1 mm3) in the reconstruction of the photons interaction point.
The working principle and the achieved results of the two experiments will be described.
09h20-10h10 : Dr Domenico della Volpe (Università di Napoli) - Unfolding the New Physics at LHC
The most recent results on the Higgs discovery with the ATLAS detector
will be presented. The mechanisms to generate the masses of the particle
in the frame of the Standard Model will be first introduced and then
the recents observation will be presented and discussed.
The success of the measurement has depended strongly on the trigger system, which is fundamental to unfold the interesting physics process from the huge background from underlying collision events.
As this is is my current area of research activity, I will present the system's architecture and implementation and discuss the relevance for the measurement.
10h10-10h40 : Coffee break
10h40-11h30 : Dr Pedro Facal (U. of Chicago) - The microwave technique for the study of the highest energy cosmic raysThe origin and composition of the ultra high energy cosmic rays (UHECRs, those with energies above 1018 eV) have been studied for long. Recent results by the Pierre Auger Observatory, a 3000 square kilometers hybrid detector with unprecedented sensitivity, have shed a light in some of the most pressing questions of the field, like the anisotropy in the arrival directions and the mass composition. But these results show also some of the limitations of the current techniques used for UHECR detection. Recent laboratory measurements suggest that detection of cosmic rays using microwave radiation in the GHz band is possible, and would allow to cover large areas, as needed, with 100% duty cycle and virtually no atmospheric attenuation. I will review the most recent UHECR measurements and present the current efforts towards GHz detection, in particular MIDAS, a prototype radio telescope instrumented with 53 microwave receivers at the University of Chicago.
11h30-12h20 : Dr Gerd Pühlhofer (Tübingen University) - Hunting cosmic ray accelerators with TeV observations: Clues from dark TeV sources and Supernova remnants
TeV observations of the Galactic plane hold the promise of identifying
the accelerators of Galactic cosmic rays. Indeed, current Cherenkov
telescopes have found a rich population of Galactic TeV gamma-ray
sources over the past few years. But identifying these gamma-ray sources
with astrophysical objects often turned out to be challenging. I will
report on lessons we learned throughout the identification process,
with a particular emphasis on supernova remnants which are believed
to be the main sources of Galactic cosmic ray particles.
12h20-13h10 : Dr Giulio Saracino (Naples University)
- An application of Silicon Photomultipliers to a tracking detector
for the muon radiography.
Silicon Photomultipliers have been developed about ten years ago and their use, as an alternative to traditional photomultiplier tubes, is increasing more and more. They have single photon response capability, high detection efficiency, high gain at low bias voltage, low power consumption and very good timing performance. In spite of their Geiger regime, they can work as linear devices. All these properties motivated their adoption for a tracker designed for the muon radiography of volcanoes (muography).
Muography is a novel technique based on the measurement of the absorption suffered by cosmic muons while traversing the volcano’s edifice. It can provide a density map of the upper part of a volcano with resolution better than 100 m. The detector is required to be able to work in harsh environment and to have low power consumption, good angular and time resolutions, large active area and modularity.
In this talk I will discuss the main properties of Silicon Photomultiplier and the design, construction and first measurements of the muon detector prototype developed for the MU-RAY project.