Month: April 2018

Graduate Seminar, 30th April

Speaker: Oleg Shkola

Title: Searches for heavy stable charged particles at Compact Muon Solenoid experiment

Abstract: Many extensions of the Standard Model (SM) predict the existence of heavy, long-lived charged particles (HSCPs). These particles might have speed significantly less than speed of light and/or charge, not equal to ±1e. With lifetimes greater than a few nanoseconds, HSCPs can travel distances larger than the typical collider detector and appear stable like pions or kaons. Because particle identification algorithms at hadron collider experiments generally assume signatures characteristic of Standard Model (SM) particles, e.g., speed close to the speed of light and a charge of ± 1e, HSCPs may go unidentified. A further complication arises from the fact that HSCPs might be charged during only a part of their passage through detectors, further limiting the ability of standard algorithms to identify them. It is however possible to detect HCPs making use of their higher rate of energy loss via ionization (dE/dx) and longer time of flight to the outer detectors, in comparison with SM particles. During the seminar, results of dedicated searches, done at Compact Muon Solenoid (CMS) experiment on data collected during 2016 will be discussed.

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.