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El límit per poder anunciar en paper seminaris i conferències en els ascensors és el divendres a les 12 hores de la setmana anterior. Amb posterioritat a aquesta data el seminari o conferència quedarà només recollit al web de la Facultat. Aleshores la publicitació en paper serà responsabilitat dels organitzadors.



Facultat de Física, Dilluns 25 de Juny de 2018, a les 12:00h

Confèrencia de l'Institut de Ciències del Cosmos

Títol: Emergence of RNA, DNA and the Origin of Life
Conferenciant: Ramanarayanan Krishnamurthy (The Scripps Research Institute, California)
Abstract:

The appearance of RNA and DNA are considered to be an important phase in the origin of life. In this context, the chemical origin of RNA and DNA must be balanced by the selection process of RNA and DNA based on their function. The presentation will focus on the structure-function relationship of RNA and DNA and elaborate on the idea that RNA and DNA are emergent species that may have co-evolved together rather than arising sequentially.

Lloc: Aula Enric Casassas
Contacte: zelhachemi@ub.edu
Web: http://icc.ub.edu/activity/1210

Facultat de Física, Dimarts 26 de Juny de 2018, a les 12:00h

Seminari de l'Institut de Ciències del Cosmos

Títol: Using the environment to infer supernova progenitor properties
Conferenciant: Lluis Galbany (University of Pittsburg, USA)
Abstract:

Integral Field Spectroscopy (IFS) applied to supernova (SN) environmental studies have shown the potential of this technique to directly characterize the galactic environmental parameters at SN locations, compare them to those at different locations of the galaxy, and put constraints on progenitor stars for different SN types. Here, I will summarize current efforts from the PISCO compilation and the AMUSING survey, that have put together more than 500 SN hosts observed with IFS, and give details about published results from these 2 datasets.

Lloc: Seminari DAM
Contacte: secretariacientifica@icc.ub.edu
Web: http://icc.ub.edu/activity/1212

Facultat de Física, Dimecres 27 de Juny de 2018, a les 12:00h

Confèrencia de l'Institut de Nanociència i Nanotecnologia

Títol: Programmable Self-Assembly of Nanocrystals
Conferenciant: Alex Travesset (Iowa State University)
Abstract:

Materials whose fundamental units are nanocrystals (NC)s, instead of atoms or molecules, are gradually emerging as major candidates to solve many of the technological challenges of our century. Those materials display unique structural, dynamical and thermodynamical properties, often reflecting deep underlying geometric, packing and topological constraints. In this talk, I will discuss the rational design of NC materials by programmable self-assembly through DNA, by electrostatic phase separation of neutral polymers, by attachment of irreversible dithiol linkers and also, through hydrocarbon and polystyrene capping ligands via solvent evaporation. I will present the Orbifold Topological Model (OTM), which successfully describes the structure of crystal or quasicrystal arrangements of NCs (superlattices) by considering capping ligands as Skyrmion textures, which determine the bonding very much like atomic orbitals in lattices of simple atoms. I will show that the OTM describes “atomic orbitals” as consisting of vortices, which enable the generation of a spontaneous valence and reveal the universal tendency of these systems towards icosahedral order. I will elaborate on the success of the OTM in describing all existing experimental structural data on single component and binary superlattices.

Professor Alex Travesset. Alex Travesset got his PhD from the Universitat de Barcelona in 1997. After Postdoc positions in Syracuse University and University of Illinois at Urbana Champaign, he joined the faculty at the Department of Physics and Astronomy at Iowa State University, where he is now full professor. He also holds an appointment as an associated scientist at the Ames lab.

Lloc: Eduard Fontseré
Contacte: isaborit@ub.edu
Web: http://www.ub.edu/in2ub/index.php?lang=en

Facultat de Física, Dijous 28 de Juny de 2018, a les 11:45h

Seminari del Dep. de Física de la Matèria Condensada

Títol: Clustering and dynamical arrest in colloidal dispersions
Conferenciant: Ramón Castañeda-Priego (División de Ciencias e Ingeniería, Universidad de Guanajuato)
Abstract:

Particle aggregation or clustering is an obligatory step in the initiation of the phase separation or the large-scale formation of materials that exhibit a heterogeneous structure, such as gels and porous media. Nevertheless, even though the macroscopic structure of such materials depends on the shape and size of the resulting clusters or aggregates, the cluster formation at equilibrium and its corresponding morphology are not fully understood. The local morphological information is also important for the identification of the physical mechanisms for arrested states of matter, especially gels and glasses, which remains a hotly debated research topic in condensed matter physics. Due to the complex nature and different microscopic details of each particular system, a general, consistent and unified definition is of paramount importance from both scientific and technological viewpoints.

Combining molecular simulations, experimental characterizations and theoretical
calculations: 1) we conclusively demonstrate that the cluster morphology in shortranged attractive colloidal systems (SRACS) at equilibrium conditions can be uniquely determined by the reduced second virial coefficient; our findings link the reversible colloidal aggregation with the extended law of corresponding states, 2) we show that gelation in adhesive hard-sphere dispersions is the result of the rigidity percolation with coordination number equal to 2.4; these results connect the concept of critical gel formation in SRACS to the universal concept of the rigidity percolation and, finally, 3) we provide a unified description and a general overview of the different aspects of the glass transition in largely asymmetric binary mixtures of hard-spheres; we highlight the fundamental relevance in considering explicitly the dynamics of both large and small particles to properly account for the glassy scenario.

Lloc: Aula Pere Pascual (A-505)
Contacte: aortiza@ecm.ub.edu
Web:

Facultat de Física, Divendres 29 de Juny de 2018, a les 11:00h

Seminari de l'Institut de Ciències del Cosmos

Títol: The LHCb Scintillator Fibre Tracker (SciFi) readout electronics
Conferenciant: Albert Comerma (Physikalisches Institut-Heidelberg Universitat)
Abstract:

The Large Hadron Collider beauty (LHCb) experiment is one of the main experiments running at the Large Hadron Collider (LHC) accelerator at the European

Organization for Nuclear Research (CERN). It is a fundamental experiment as it can provide evidence of physics beyond the limits of other direct measurements performed by the other experiments at LHC.

LHCb will undergo a major upgrade during Long Shutdown 2 (2019) with one of the main changes being the full replacement of the main tracking system. The new tracker will use SCintillating Fibres (SCiFi) to cover the complete area of the detector. The 2.5m long fibre mats are built winding 250 micrometers diameter Scintillator
Fibres one on top of each other to obtain 6 layers (approximately 1.5mm height). In the middle of the detector a mirror helps to collect all the photons generated in the fibres to overcome attenuation length (damaged after irradiation). When a particle passes through the mat a small and fast light pulse is generated. A custom designed
array of Silicon Photo-multipliers (SiPMs) then converts the light burst into electrical charge that is collected and processed by the readout electronics. Each array provide 128 channels (0.25mmx1.62mm each) to be readout by the electronics. The fibres and the sensors have the same size but they are not paired. As a consequence, the
scintillation light is typically distributed among several channels, requiring a clustering process after readout.

The need to achieve as high as possible efficiency and handling the high occupancy leads to very challenging constraints in space, power and signal timing triggering the design of an Application Specific Integrated Circuit for the readout. The low Power ASIC for the SCIntillator FIbre TraCker (PACIFIC) has been developed for this purpose. PACIFIC integrates 64 readout channels including pre-amplifier,
shaper, gated integrator and Analog to Digital Conversion (comparators) prior to a digital readout (serialization). Analog chain behaviour is controlled using a standard I2C slave and configuration registers.

The first talk of the talk will summarize the main detector elements and construction status while the second part will focus on the mixed signal design with special emphasis on the design closure process before submission.

Lloc: Seminari DAM
Contacte: dgascon@fqa.ub.edu
Web: http://icc.ub.edu/activity/1211

Facultat de Física, Divendres 29 de Juny de 2018, a les 12:00h

Seminari del Dep. de Física Quàntica i Astrofísica

Títol: Electroweak precision tests at hadron colliders
Conferenciant: Giuliano Panico (IFAE)
Abstract:

High-energy processes at the LHC are potentially powerful indirect probes of heavy new physics, whose effects can be encapsulated in higher-dimensional operators or in modified Standard Model couplings. The energy growth of new-physics effects in a broad class of processes makes them sensitive targets of the LHC large kinematic reach, provided accurate enough measurements are possible. In this talk I give an overview of this topic and discuss, in particular, how dilepton and diboson processes can allow us to obtain precision electroweak measurement at the LHC and future colliders

Lloc: Aula 507 (Pere Pascual)
Contacte: vicente.atal@icc.ub.edu
Web:

Facultat de Física, Dilluns 09 de Juliol de 2018, a les 12:15h

Seminari de l'Institut de Ciències del Cosmos

Títol: Non-thermal processes in stellar bow-shocks
Conferenciant: Dr. Santiago del Palacio ( Instituto Argentino, IAR (CONICET-CCT La Plata, CICPBA - Facultat de Ciencias Astronómicas y Geofísica de La Plata, FCAGLP (UNLP)
Abstract:

Runaway, massive stars produce bow-shocks in the interstellar medium.
The thermal emission from these bow-shocks is usually observed at IR wavelengths. However, these bow-shocks are also suitable for the acceleration of relativistic particles, but the detection of their predicted high-energy emission remains elusive. So far only the non-thermal radio emission from the bow-shock of BD+43°3654 has been detected.
In this talk we review the basics of the non-thermal physics that take place in stellar bow-shocks, and present a radiative model that takes into account the spatial structure of the emitting region. The model predicts the evolution and the emission of the relativistic particles accelerated along the bow-shock. We apply this model to the specific case of BD+43°3654 and show a good agreement between synthetic and observed radio-cm synchrotron maps. We also provide updated predictions of the expected X-ray and gamma-ray luminosities.
Finally, we discuss the non-thermal broadband spectral energy distributions for different generic scenarios. By means of a simplified, one-zone model approximation, we can infer how the different stellar and ambient parameters affect the luminosity of the different processes. In this way we can efficiently assess future surveys that look for non-thermal emission from stellar bow-shocks across the electromagnetic spectrum.

Lloc: Seminari DAM. 724
Contacte: vbosch@fqa.ub.edu
Web: https://www.ub.edu/portal/web/dp-fquanticaastrofisica