Graduate Seminar, 23rd April

Speaker: Katarzyna Frankiewicz

Title: Search for dark matter induced neutrinos with the Super-Kamiokande detector .

Abstract: Indirect searches for dark matter are performed based on atmospheric neutrino data collected with the Super-Kamiokande (SK) detector in years 1996-2016. The excess of neutrinos from possible dark matter sources such as Earth and Galactic Center, compared to the expected atmospheric neutrino background is searched. Angular distributions and energy spectra as expected for signal and background are taken into account and various dark matter annihilation channels are considered. All event samples (fully-contained, partially-contained along with upward-going muons), including both electron and muon neutrinos, covering a wide range of neutrino energies (GeV to TeV) are used. The allowed number of dark matter induced neutrinos which can be contained in SK data so far is estimated. Obtained limits on dark matter induced neutrino flux from the Earth’s core are related to the limit on spin-independent WIMP-nucleon scattering cross section and compared against the results of direct detection experiments. In case of the Galactic Center analysis, the upper limit on the dark matter self-annihilation cross-section is derived.

Graduate Seminar, 16th April

Speaker: Jakub Sierchuła

Title: Dual Fluid Reactor – neuronics and fuel cycle modeling

Abstract: Dual Fluid Reactor (DFR) is a novel concept of a fast heterogeneous nuclear reactor which falls-off the classification of Generation IV International Forum (GIF). Its key feature is the employment of two separate liquid cycles, one for fuel and one for the coolant. In the DFR both cycles can be separately optimized for their respective purpose, leading to advantageous consequences: a very high power density resulting in cost savings, and a highly negative temperature feedback coefficient, enabling self-regulation without any control rods or mechanical parts in the core. During a seminar, reactor core model with new eutectuc U-Cr fuel composition and liquid lead as a coolant will be presented. The neutron flux density as a function of the energy in core was calculated, as well as fuel burn-up and effective multiplication factor/reactivity changes during reactor operation. In the reference design, fuel circulates at an operating temperature of 1300 K and can be processed on-line in a small internal processing unit utilizing fractionated distillation or electro refining. Except for heat or electricity generation, the unit with Dual Fluid Reactor could provide away some medical radioisotopes like Mo-99/Tc-99m.

 

Graduate Seminar, 9th April

Speaker: Sarah Allen

Title: Simulation and analysis of detective quantum efficiency in mammography

Abstract: The detective quantum efficiency (DQE) of an imaging device describes its ability to preserve the signal to noise ratio from the radiation field to the resulting image data. Since in X-ray imaging the noise of the radiation field is heavily dependent on the air kerma, DQE values are used to describe the dose efficiency of a device. In this seminar, I will outline why DQE is used to quantify image quality in radiographic systems and how it is calculated. I will also discuss these things in context of a mammography unit.

Graduate Seminar, 26th March

Speaker: Artur Miroszewski

Title: Evolution in classical and quantum systems

Abstract: Although people tend to understand intuitively the passage of time, its status in physical theories is still puzzling. During the talk I will distinguish between notions of time and clocks and I will motivate why only the latter has a physical significance. Using this assumption I will introduce reformulated theory of classical mechanics in which one can easily change clock (so called pseudo-canonical transformations) with respect to which the dynamics is observed.
I will then quantize the new theory and study what impact the new formulation has on our basic understanding of quantum mechanics.

Graduate Seminar, 19th March

SpeakerVarvara Batozskaya

Title: Measurement of CP observables in B0s->J/psi(ee)Phi(KK) decay at the LHCb experiment

Abstract: The determination of the CP-violating phase phi_s in B0s->J/psiPhi decays is one of the key goals of the LHCb experiment. Its value is predicted to be very small in the Standard Model. However, it can be significantly enhanced by contributions from effects of new physics. The first measurement of the CP-violating parameters in electron mode of the B0s->J/psiPhi decay using Run1 data collected at the LHCb will be discussed.

Graduate Seminar, 12th March

Speaker:  Chetan Bavdhankar

Title: Our velocity and acceleration in the Universe are in the same direction! (Local Group Motion using Supernova type Ia)

Abstract: Supernova type Ia (SN Ia) are one of the accurate distance indicators which are used to measure the distances to distant galaxies. Using the redshift of the galaxy and it’s distance (estimated from SN Ia) we can measure its peculiar velocity. Nearby galaxies in the Universe are bound gravitationally and these bound systems of galaxies are called galaxy groups. We are part of such group which is called ‘The Local Group’ (LG), Andromeda galaxy is also member of this group. These galaxy groups show motion due to nearby masses such as other groups, clusters and superclusters. Our Local Group is also showing such motion and this motion can be seen in CMB dipole. To estimate the responsible masses for this motion of Local Group, dipole in peculiar velocities is useful. This dipole in peculiar velocities has the information about effective distance that can cause our group’s motion. In my work, I have tried to calculate that distance. As SN Ia are not very frequent events, we don’t have enough data points to get very accurate results so we need to generate artificial data more realistically. I have used velocity fields in the Local Universe to generate such a artificial SN Ia data and got the results which says that ‘Our velocity and acceleration in the Universe are in the same direction!’

Graduate seminar, 5th March

Speaker: Piotr Warzybok

Title: Modelling of Processes Governing Selective Laser Melting

Abstract: The processing parameters of Selective Laser Melting (SLM) technique have a significant impact on the functional properties of the materials. It is known that time efficient fabrication of high-quality parts with desired microstructures requires understanding of their interactions in more detail than by calculating energy density. During the talk I will introduce mechanical and structural properties of standard 316L stainless steel fabricated using SLM technique. The basics of the modelling of physical phenomena governing SLM will be discussed.

Graduate Seminar, 26th February

Speaker: Szymon Nakoneczny

Title: Natural language processing methods in biological activity prediction and quasar detection in large scale photometric surveys.

Abstract: The first part will focus on my master ‘s thesis. Virtual screening is a process in which databases of chemical compounds are searched in order to f ind structures characterized with a high biological activity, possible drug candidates. The goal is to classify active compounds by combining the natural language processing methods with a text representation of compounds. The second part is going to cover an approach of detecting quasars with means of machine learning. Because it is not possible to fully sample extragalactic objects with spectroscopy, quasars analysis requires a proper automated approach based on photometric surveys. We are going to focus on describing a problem and showing preliminary results of our approach.

Graduate Seminar, 19th February

SpeakerGrzegorz Żarnecki

Title: Measurement of muon-antineutrino charged current cross section with single pion production in the near detector of T2K experiment

Abstract: Cross section measurement is a basic tool to examine agreement between theoretical models and experimental data. The fundamental struggle is to separate signal sample from background events. Decent measurement requires nontrivial methods in order to minimize dependency on the default model and include characteristics of the detector. This will be illustrated on the example of muon-antineutrino CC interaction on carbon with single pion production in ND280 detector of the T2K experiment.