Seminars
Laboratory of High Energy Physics, Astrophysics and Advanced Technologies organizes laboratory seminars every week through which the last results obtained are reported by group members.
Thursday, April 11, 2013, 12:00 |
| Title of presentation: Estimates of the Energy and Flux of the Ultra-High-Energy Cosmic Rays using the Spin-Down Model of Black Holes |
| Seminar presented by: PhD Ioana Dutan |
| Place: ISS Seminar room, IFA Building, 2nd floor |
| Abstract: Cosmic rays (CRs) are relativistic particles of extraterrestrial origin, consisting mainly of protons, alpha particles, and other atomic nuclei but also including some high energy electrons and photons. They enter Earth's atmosphere, collide with atomic nuclei, and produce many secondary particles, principally pions, muons, electrons, neutrinos, as well as gamma rays, which all together form the so-called CR air shower. Ultra-high-energy cosmic rays (UHECRs) have energy greater than 1018 eV. By studying CRs we can, for instance, find information on the chemical evolution of the universe or improve constraints on Galactic and extragalactic magnetic fields. In this talk, I present the results of our investigation of the production of UHECR in jets from low-luminosity active galactic nuclei (AGN). We propose a model for the UHECR contribution from the spin-down power of black holes at the center of an AGN, which present a jet power Pj ≤ 1046 erg s-1. This is in contrast to the opinion that only high-luminosity AGN can accelerate particles to energies ≥ 50 EeV. Next, we apply the model to a complete sample of 29 steep spectrum radio sources with a total flux density greater than 0.5 Jy at 5 GHz to make predictions for the maximum particle energy and flux of the UHECRs from nearby AGN. These predictions are then used in the Monte Carlo simulations of the UHECR propagation from their sources to the Earth to obtain a sky map for the UHECR events. Finally, we compare the spectral energy distribution of the predicted UHECR events with that observed by the Pierre Auger Observatory. |
Friday, April 5, 2013, 10:30 |
| Title of presentation: New Insights into the Origin and Evolution of CMEs |
| Seminar presented by: Assoc. Prof. Ilia Roussev, Institute for Astronomy, University of Hawaii, USA |
| Place: ISS Seminar room, IFA Building, 2nd floor |
| Abstract: Coronal Mass Ejections (CMEs) play a leading role in driving the Sun-Earth System (SES) because of their large-scale, energetics and direct impact on the Earth. As CMEs evolve in heliospace they drive shocks, which act to produce Solar Energetic Particles (SEPs). CMEs and SEPs can strike our planet, and they can disrupt satellites and knock out power systems on the ground, among other effects. That is why it is important to better understand and predict the ever-changing environmental conditions in outer space due to solar eruptive events, the so-called Space Weather.This talk summarizes recent advances in modeling the evolution of Coronal Mass Ejections in the low solar corona and inner heliosphere by means of 3-D compressible MHD simulations. By comparing simulations results with directly observable quantities (e.g., Thompson-scattered white light, EUV, and X-ray intensities), it becomes possible to constrain the physical models of CMEs, and learn a great deal about the interaction of the ejecta with the pre-existing magnetic field and ambient solar plasma. We will present new physical insights into the evolution of CMEs gathered from our numerical investigations. |
Thursday, March 21st, 2013, 12:00 |
| Title of presentation: Methods used in detecting intermittency transition to chaos for the "nuclear billiard" |
| Seminar presented by: PhD Daniel Felea |
| Place: ISS Seminar room, IFA Building, 2nd floor |
| Abstract: We analyze on a classical 2D version of the "nuclear billiard" the onset of chaotic behaviour of the three-dimensional nucleonic trajectories in different dynamical states of the axially symmetric deformed nuclei. The coupling between the single-particle and the collective degrees of freedom in the presence of dissipation for several multipolarities is taken into account. We examine the order-to-chaos transition by performing several types of analysis including sensitive dependence on the initial conditions, single-particle phase space maps, fractal dimensions of Poincare maps, autocorrelation functions, configuration and kinetic energy spaces, power spectra, Shannon entropies and Lyapunov exponents. For the monopole and dipole deformations an increasing divergence of the nucleonic trajectories from the adiabatic to the resonance regime is observed. Also, a peculiar case of intermittency is reached in the vicinity of the resonance, for the monopole case. The quantity of energy transferred in a nuclear collision is shown to be the control parameter which adjusts the intermittent behaviour of the studied system. |
Thursday, February 28, 2013, 12:00 |
| Title of presentation: Particle production rates and their pt spectra in ALICE |
| Seminar presented by: PhD Adrian Sevcenco |
| Place: ISS Seminar room, IFA Building, 2nd floor |
| Abstract: This is the first in a series of seminars aimed to disseminate ALICE results, experiment in which ISS is involved since 2006. The presentations will be subjected to main physics categories studied at ALICE, experiment which aims to study QGP, state of matter predicted by QCD. This presentation will focus on results related to global event characterization and particle productions. Event characterization plays a crucial role in determining the geometry of interaction for the event in heavy ion collisions. Taking this characterization by studying the multiplicity distribution function of centrality and using models linking particle density by the range of rapidity and pt distributions one can obtain a complete characterization of the event. |
Thursday, February 21st, 2013, 11:00 |
| Title of presentation: Electronic board upgrade of the Cerenkov detectors used in the cosmic ray detection from Pierre Auger Observatory |
| Seminar presented by: PhD Marian Mogildea |
| Place: ISS Seminar room, IFA Building, 2nd floor |
| Abstract: The Pierre Auger Observatory study ultra-high-energy cosmic rays having energies above 10 19 eV. In the cosmic ray detection the Pierre Auger Observatory uses radio detection systems and optic detection systems. One of the most important detectors used in Pierre Auger Observatory are Cherenkov detectors. The surface arrays contain 1600 Cherenkov detectors stations; these are distributed over 3000 km2. In this presentation are described actual front-end electronics and signal electronics system acquisition used in the Pierre Auger Observatory. Also are discussed the electronic board upgrade of the Cerenkov detectors used in the cosmic ray detection from Pierre Auger Observatory. |
Thursday, February 7, 2013, 11:00 |
| Title of presentation: Study of internal structure of stars. Evolution of stars |
| Seminar presented by: PhD Iuliana Bacioiu |
| Place: ISS Seminar room, IFA Building, 2nd floor |
| Abstract: |
Friday, February 1st, 2013, 12:00 |
| Title of presentation: Intermittency effect in QCD jets at TeV scale |
| Seminar presented by: PhD Student Ciprian Mihai Mitu |
| Place: ISS Seminar room, IFA Building, 2nd floor |
| Abstract: The structure of jets in hadronic collisions (p-p, N-N) is studied in terms of density fluctuations in particle production. The presence of intermittency (i.e. physical fluctuations in particle
production) induce a departure from the classical statistical fluctuations with a poissonian distribution. The TeV colliding energy and high luminosity from LHC makes this type of analysis free of statistical uncertainties even at high resolution in rapidity,
azimuth angle and transverse momentum. |
Wednesday, January 23, 2013, 12:00 |
| Title of presentation: Magnetic field generation via Kelvin-Helmholtz instability in sheared plasmas with applications for astrophysical jets |
| Seminar presented by: PhD Ioana Dutan |
| Place: ISS Seminar room, IFA Building, 2nd floor |
| Abstract: Observational data suggest that the relativistic jets in active galactic nuclei (AGN) and gamma-ray bursts (GRBs) are cylindrically stratified with a fast, inner spine and a slower, outer sheath.
The resulting boundary layer can be a site of generation of magnetic fields due to plasma instabilities. After a short introduction to AGN jets and Kelvin-Helmholtz instability, I will present the results of relativistic particle-in-cell (R-PIC) simulations
of shear layers in electron-proton jets, where the magnetic fields are generated by the kinetic Kelvin-Helmholtz instability. |
Thursday, December 6, 2012, 12:00 |
| Title of presentation: Analysis of the testbeam data for BeamCal Sensors |
| Seminar presented by: PhD Veta Ghenescu |
| Place: ISS Seminar room, IFA Building, 2nd floor |
| Abstract: |
Wednesday, June 20, 2012, 12:00 |
| Title of presentation: On the possibility to discriminate the mass of the primary cosmic ray using the muon arrival times from extensive air showers: Application for Pierre Auger Observatory |
| Seminar presented by: PhD Student Nicusor Arsene |
| Place: INFLPR Seminar room, 2nd floor |
| Abstract: |
Wednesday, June 6, 2012, 12:00 |
| Title of presentation: A general presentation of R3B-FAIR experiment |
| Seminar presented by: PhD Madalin Cherciu |
| Place: INFLPR Seminar room, 2nd floor |
| Abstract: |
Friday, May 18, 2012, 12:00 |
| Title of presentation: Quarkonium production at the high energy frontier |
| Seminar presented by: PhD Ionut Cristian Arsene |
| Place: INFLPR Seminar room, 2nd floor |
| Abstract: |
Thursady, May 3, 2012, 12:30 |
| Title of presentation: GPU Programming: CUDA and OpenCL |
| Seminar presented by: Student Bogdan Dumitru |
| Place: INFLPR Seminar room, 2nd floor |
| Abstract: |
Thursday, May 3, 2012, 12:00 |
| Title of presentation: An introduction to GRID |
| Seminar presented by: PhD Student Ionel Stan |
| Place: INFLPR Seminar room, 2nd floor |
| Abstract: |
Wednesday, March 21, 2012, 12:00 |
| Title of presentation: Becquerel Project - General presentation |
| Seminar presented by: PhD Student Alina-Tania Neagu |
| Place: INFLPR Seminar room, 2nd floor |
| Abstract: |
Wednesday, March 7, 2012, 12:00 |
| Title of presentation: The ALICE Experiment - A general presentation |
| Seminar presented by: PhD Daniel Felea |
| Place: INFLPR Seminar room, 2nd floor |
| Abstract: |
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