All future and past seminars
SPRING semester 2019
Jan. 30 : Prof Francesco RIVA, Université de Genève, DPT - Access to the talk
Title : Higgs Couplings without the Higgs
The measurement of Higgs couplings constitutes an important part of present Standard Model precision tests at colliders. In this article, we show that modifications of Higgs couplings induce energy-growing effects in specific amplitudes involving longitudinally polarized vector bosons, and we initiate a novel program to study these very modifications of Higgs couplings off-shell and at high-energy, rather than on the Higgs resonance. Our analysis suggests that these channels are complementary and, at times, competitive with familiar on-shell measurements; moreover these high-energy probes offer endless opportunities for refinements and improvements.
Fev. 27 : Dr Jamie BOYD, CERN - Access to the talk
Title : Looking forward to new physics: the FASER experiment
The goal of the FASER experiment is to search for new light, weakly-interacting particles at CERNs Large Hadron Collider. By exploiting a unique location underground in the CERN tunnel system, FASER will provide world-leading sensitivity in a relatively small, quick, and inexpensive experiment. The FASER detector is currently under construction to be installed into the tunnel during 2020 in LHC Long Shutdown 2. This seminar will describe the physics motivations, detector design, and expected performance of FASER as well as the physics prospects.
Mar. 6 : Dr Edda GSCHWENDTNER, CERN - Access to the talk
Title : AWAKE : Accelerating electrons to GeVs in a proton driven plasma wakefield experiment
AWAKE is an accelerator R&D experiment at CERN to demonstrate for the first time ever plasma wakefield acceleration of electrons in wakefields driven by a proton bunch and, in the future, take advantage of the large energy store in the proton bunch to reach very high energy gain in a single plasma.
In 2016/2017 AWAKE has achieved a major milestone and observed the strong modulation of high-energy proton bunches in plasma; the results represent the first ever demonstration of strong plasma wakes generated by proton beams. In May 2018 AWAKE demonstrated for the first time the acceleration of externally injected electrons to multi-GeV energy levels in the proton driven plasma wakefields, a result recently published in Nature.
The aims of AWAKE Run 2 (2021 - 2024) are to achieve high-charge bunches of electrons accelerated to high energy, about 10~GeV, while maintaining beam quality through the plasma and showing that the process is scalable. The final goal by the end of AWAKE Run 2 is to be in a position to use the AWAKE scheme for particle physics experiments.
An introduction to plasma wakefield acceleration is given. AWAKE experiment is described. The recent results are shown. The design and challenges of AWAKE Run 2 are presented. Particle physics experiments based on the AWAKE acceleration scheme are introduced.
Mar. 13 : Prof. Holger FRÖNING, Heidelberg University - Access to the talk
Title : An Efficient Reduce-and-Scale Architecture for DNN-based Inference on Resource-Constrained Systems
While Deep Learning is becoming ubiquitous in computing, being deployed in systems ranging from data centers to mobile devices, its computational complexity is huge. Contrary, while resource-constrained systems steadily improve their processing power, there is a huge gap to the demands of deep neural networks. Furthermore, CMOS technology projections show that performance scaling will be increasingly difficult, due to reasons including power consumption and eventually limited component scaling.
In the DeepChip collaboration, we gear to design software architectures that improve the mapping of DNNs to resource-constrained systems. In this talk, we will shortly review basics and recent related work, before we introduce the main concept of DeepChip, which is based on a reduce-and-scale architecture and allows to remove redundancies found in typical DNNs, thereby allowing an improved deployment on mobile or embedded systems. We will conclude with a couple of anticipated research directions.
Mar. 20 : Prof. Marco ZANETTI, Padova University - Access to the talk
Title : Prospects for a Muon Collider to probe the Energy Frontier
Using muons as probes exceeding the energy scale reached by the LHC is a tantalising idea. A Muon Collider would in fact have a unique physics potential, making such a machine a dream for the HEP community. Will this dream ever become reality depends on whether the numerous technological challenges posed by the project will be overcome. Several schemes have been proposed in the years, all addressing in different ways key issues such as the production of high brilliance muon beams, its acceleration and the management of the beam induced radiation. In this seminar, after some (obvious) considerations supporting the physics case, I will review the studies performed so far and latest developments on the various project's components. I will focus in particular on the recent proposal of a positron induced low emittance muon source (LEMMA) and the required R&D to prove its feasibility.
Apr. 17 : Dr Merlin KOLE, Université de Genève, DPNC
Title : POLAR: The first detailed polarization measurements of the brightest explosions in the Universe
Gamma-Ray Bursts (GRBs) are the most violent explosions in the Universe since the Big Bang. These events, which despite occurring millions or even billions of light years away, are observed approximately once per day. Some are thought to be the result of the death of very massive stars while, thanks to gravitational wave measurements, a subset was recently shown to be the result of the merging of 2 neutron stars. The extreme brightness of these events allowed them to be discovered by accident more than 50 years ago by some of the first gamma-ray detectors operating in space. While since then great progress was made in our understanding of these events through studies of the arrival time, direction and energy of the gamma-rays emitted in these explosions, many open questions remain and appear difficult or even impossible to be answered using conventional studies. In recent decades theoretical studies have indicated that a wealth of information is contained in the one remaining unmeasured parameter of these photons: their polarization.
The POLAR instrument was designed specifically to provide the first detailed polarization measurements of GRBs. POLAR was developed by a collaboration of institutes in Switzerland, Poland and China, and launched in September 2016 as part of the second Chinese space lab, the Tiangong-2. It took data for a total of 6 months during which it detected a total of 55 GRBs as well as several other astrophysical objects. The complicated polarization analysis of 5 of these GRBs was recently completed. The results indicate that the polarization is more complicated than any of the existing models suggest. During this talk I will provide an introduction to GRB astrophysics, discus the history of the POLAR mission and present the first results of this mission and their interpretation (or at least explain the lack thereof).
May 15 : Prof. Pawel MOSKAL, Jagiellonian University, Krakow, Poland
Title : J-Pets plastic revolution
May 22 : Dr Graeme STEWART, CERN
Title : HEP software foundation
May 29 : Prof. Susanne MERTENS, TUM, Munich
Title : Neutrino masses
Autumn semester 2018
Sept. 19 : Dr Philipp ELLER, Penn State University - Access to the talk
Title : Neutrino Oscillation Physics with IceCube
The Neutrino IceCube observatory, with its 5160 sensors submerged in Antarica's glacial ice, collects data from neutrino events over several orders of magnitude in energy. The DeepCore detector sub-array in the deepest clear ice of IceCube enables detection and reconstruction of neutrinos produced by the interaction of cosmic rays in the Earth’s atmosphere at energies and baselines suitable for the study of neutrino of oscillations.
We recently unblinded two different 3-year analyses using neutrinos with reconstructed energies between 5.6 and 56 GeV over a range of baselines up to the diameter of the Earth to simultaneously measure the muon neutrino disappearance and tau neutrino appearance. These new results are competitive in terms of precision with those of other, mainly long baseline accelerator experiments.
Sept. 26 : Prof. Martin KUNZ, Unige - Access to the talk
Title : Overview of the ESA Euclid satellite mission
I will give an overview of the Euclid satellite, first focusing on the
mission status and outlook, and on the consortium structure, including
the activities in Switzerland. I will then review the science goals and
place them into the current cosmological context.
Oct. 03 Dr Michael DOSER, CERN - Access to the talk
Title :Experiments on antimatter at CERN
One and a half decades after the first production of “cold” antihydrogen, first precision measurements of the properties of antihydrogen have recently begun. Together with the start-up of an additional dedicated low energy antiproton decelerator (ELENA), and the development of a wide range of techniques that permit precise atomic measurements, the study of antihydrogen atoms has started in earnest. This presentation will provide an overview of the present status and outlook for fundamental physics with antihydrogen atoms. A special focus will be put on tests of gravity with antimatter and on the AEGIS experiment, which in a first step aims to measure the free fall of a pulsed beam of antihydrogen atoms over their parabolic trajectory, as well as on the technological developments from a variety of fields on which it relies.
Oct. 17 : Dr. Mieczyslaw (Witold) KRASNY - Sorbonne University Paris and BE-ABP Division CERN - Access to the talk
Title : The Gamma Factory for CERN: conceptual foundation, feasibility studies and research opportunities
In this talk I shall discuss the initiative of broadening the present CERN research programme by including a new component exploiting a novel concept of the light source. The proposed, partially stripped ion beam driven, light source is the backbone of the Gamma Factory initiative. It could be realized at CERN by using the infrastructure of the already existing accelerators. It could push the intensity limits of the presently operating light-sources by at least 7 orders of magnitude, reaching the flux of the order of 10^17 photons/s, in the particularly interesting gamma-ray energy domain of 0.1 — 400 MeV.
The partially stripped ion beams, the unprecedented-intensity energy-tuned gamma beams, together with the gamma-beam-driven secondary beams of polarized positrons, polarized muons, neutrinos, neutrons and radioactive ions constitute the basic research tools of the Gamma Factory. A broad spectrum of new research opportunities, in a vast domain of uncharted fundamental and applied physics territories, could be opened by the Gamma Factory.
Examples of new research opportunities and the recent progress in the project development will be presented in this talk.
Oct. 31 : Dr Pasquale SERPICO, LAPTh (CNRS & Univ. of Savoie) Annecy, France - Access to the talk
Title : "Quo vadis, materia nigra?"
The main outcome of decades of efforts for the identification of dark matter (at colliders, direct detection underground, indirect detection via astrophysical signals) is a null result. What lessons have we learned, if any? Which models are still viable, and with what motivations? I will review some of the trends in the theoretical and phenomenological dark matter community and a few of the observational opportunities that will open up in the forthcoming years, in particular in indirect techniques.
Nov. 07 : Dr Stefan SCHLENSTEDT, DESY - Access to the talk
Title : Gamma-ray Astronomy - Recent Highlights from VERITAS
A short introduction to gamma-ray astronomy, a new field in astronomy and astroparticle physics, will be given. VERITAS is a ground-based gamma-ray observatory consisting of an array of four atmospheric Cherenkov telescopes located in southern Arizona, USA. VERITAS carries out an extensive observation program of the gamma-ray sky with a sensitivity in the energy range from 85 GeV to > 30 TeV. Recent highlights of the VERITAS observation program of extragalactic sources will be presented like active galactic nuclei and other extragalactic objects like radio galaxies and starburst galaxies. The studies of the extragalactic background light will be discussed. Also recent results on galactic accelerators will be presented like supernova remnants with fast shocks, pulsars with powerful winds and intensely-interacting binary systems.
Nov 14 : Prof. Iwona GRABOWSKA-BOLD, AGH University of Science and Technology, Poland - Access to the talk
Title : First direct measurement of light-by-light scattering
Light-by-light scattering is a process in which two photons interact with each other and in consequence change a direction of their motion. This phenomenon is forbidden in the classical physics. Only after the birth of quantum electrodynamics in the 30th of the XX century, Heisenberg and his student Euler realized that two photons may interact with each other. Unfortunately for decades that process has stayed elusive for direct measurements due to its tiny cross section. A breakthrough has occurred in 2017 when the ATLAS Collaboration at the LHC analysed data from lead-lead collisions collected at the center-of-mass energy of 5.02 TeV. A focus was given to a special class of events, so-called ultra-peripheral collisions (UPC), in which two lead nuclei do not collide but pass next to each other. UPC events are considered a source of high-intensity electromagnetic fields, thus photons. In 4 billion analysed events, the ATLAS Collaboration found 13 event candidates with scattered photons, while about 2 were expected from background processes. This measurement established evidence for a first direct measurement of light-by-light scattering. In October 2018 also a result of light-by-light scattering from the CMS Collaboration was released. This talk will discuss the analysis, results of the measurements, and also prospects for future analyses of lead-lead data including the ongoing 2018 run.
Dec 05. : Prof. Ben KILMINSTER, Uni Zurich
Title : DAMIC-M : probing 10 orders of magnitude in dark-matter mass
The DAMIC-M experiment will have sensitivity beyond current limits for dark matter in a range of over 10 orders of magnitude in dark-matter mass. The DAMIC (Dark Matter in CCDs) experiment uses CCD detectors as targets for the detection of dark matter. Cooled CCD detectors have very low thermal and electronics noise, allowing them to detect very small ionization signals, which are produced by nuclear recoils, electronic recoils, and photon absorption within the depleted substrate. DAMIC-M is the third DAMIC experiment, and will be located 2 hours from CERN, in the laboratoire souterrain de Modane (LSM). The first DAMIC experiment, located in a shallow underground site at Fermilab, reported the world's best limits for weakly interacting massive particles (WIMPs) with masses below 4 GeV. The second DAMIC experiment is currently operating at SNOLAB, and has achieved higher mass, significantly lower backgrounds, and with a better understanding of the efficiency for detecting potential dark matter signals. The DAMIC-M experiment is now approved and funded. It will consist of a detector with 10 times larger mass, 50 times lower background rates, and 10 times lower electronics readout noise. The achieved, extremely low electronics noise, of 0.1 electrons, allows for single electrons to be detected with impressive resolution. DAMIC-M is being optimized to search for hidden-sector dark matter over a wide range of mass values that are predicted by different hidden-photon scenarios, as well as WIMPs in the 1-GeV mass range.
Dec. 12 : Prof. Florian BERNLOCHNER, KIT, Germany - Access to the talk
Title : Fantastic Bs and where to find them
The next-generation super B-Factory Belle II recently recorded its first collisions. I will review the current status of the experiment and take you on a tour about what fantastic Bs we will be able to measure. In particular, I will show you first rediscovery plots and highlight several experimental techniques we developed and refined at KIT, such as the full event interpretation or a deep neural network based flavour tagger. The talk will close with an outlook about the future and a summary how LHCb and Belle II complement each other.
Jan. 16 : Prof. Hugo ZBINDEN, Unige - GAP - 10H15
Title : Quantum Computing and Cryptography
The Quantum Computer is a threat for today’s cryptography. Indeed, it could factorize large numbers efficiently and make the current public key cryptography obsolete. Interestingly, Quantum Physics is also at the origin of a solution of distributing keys in a secure way: The quantum key distribution.
In this talk a will briefly introduce the quantum computer (be aware I am not a specialist) and then explain how quantum key distribution works. I will present the state of the art of QKD and discuss the possibilities and limits.