Graduate Seminar, 23rd May

Speaker: Dobromił Załoga

Title: Research on emission of visible and X-ray radiation, and estimations of electron temperature in discharges of Plasma-Focus type

Abstract: This presentation reports on results of detailed experimental studies of the visible and x-ray emission, as well as estimations of plasma electron temperatures in discharges of the Plasma-Focus (PF) type, particularly in the PF‑1000U facility at IPPLM. In particular there are summarized measurements of the visible radiation from PF discharges, measurements performed by means of laser interferometry, time-integrated measurements of x-rays, as well as time-resolved measurements of soft x‑rays, which were performed by means of framed MCP (Micro-Channel Plate) and “pinhole” cameras equipped with scintillation detectors, as well as by means of a set of 4 semiconductor PIN-type diodes equipped with appropriate absorption filters. It was shown that the formation of different microstructures inside the dense and hot plasma column during PF‑type discharges depends strongly on experimental conditions, and particularly on gas conditions. At the same experimental conditions microstructures in form of plasma-current filaments are relatively well reproducible in the macroscopic scale, but microstructures in form of hot-spots are irreproducible. Due to a stochastic character of the formation of such microstructures, their parameters (i.e. positions, lifetime, density and electron temperature) can differ considerably, e.g. local values of electron temperature Te can change in a range from about 100 eV to about 880 eV.

Graduate seminar, 16th May

Speaker: Michał Palczewski

Title: „Detailed illustration of accuracy of presently used nuclear-mass models”

Abstract: The accuracy of used nuclear – mass models plays important role in nuclear research and is still being developed by different scientific groups. During the seminar I would like to focus more on that topic mentioned in my last talk. Different approaches to this problem give different accuracies but the precision of each model varies in different regions of nuclear chart. This can be represented by simple but very useful and detailed pictures showing the deviations between masses (experimental and theoretical one) for each nucleus. Later these data can be applied in research, e.g. in improvements of known models and in the prediction of values of masses of still unknown isotopes; with the predictive power seen mostly in macro-micro models. However, what should be mentioned, especially with other models, a model predicting well known masses doesn’t have to work well in the prediction of unknown ones, showing the problem of need of using appropriate models in a given area of the research.

Graduate Seminar, 9th May

Speaker: Katarzyna Frankiewicz

Title: The CosmicWatch project

Abstract: CosmichWatch is a simple, physics-motivated machine- and electronics-shop project for university students and schools. Our detector is a self-contained apparatus that employs a plastic scintillator as a detection medium and a silicon photomultiplier for light collection. The detector can be battery powered and used in conjunction with the provided software to make interesting physics measurements.

Venue: Room 22, 9:00 A.M.

Graduate Seminar, 25th April

Speaker: Jakub Sierchuła

Title: Dual Fluid Reactor – concept for new fast nuclear reactor

Abstract: Dual Fluid Reactor (DFR) is a novel concept of a fast heterogeneous nuclear reactor. Its key feature is the employment of two separate liquid cycles, one for fuel and one for the coolant. As opposed to other liquid-fuel concepts like the molten-salt fast reactor (MSFR), 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. The fuel liquid, an undiluted actinide trichloride (consisting of isotope-purified 37 Cl) in the reference design, 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. Medical radioisotopes like Mo-99/Tc-99m are by-products and can be provided right away. In a more advanced design, an actinide metal alloy melt with an appropriately low solidus temperature is well possible which further compactifies the core and allows to further increase the operating temperature due to its high heat conductivity. The best choice for the coolant is pure lead which yields a very hard neutron spectrum.

 

Graduate Seminar, 4th April

Speaker: Sarah Allen

Title: Dose Distribution Analysis for Stereotactic Radiotherapy

Abstract: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiotherapy (SRBT) have become important tools for treating cancers or other malformations that are close to critical organs, or otherwise difficult to reach using conventional surgery. My talk will outline the principles behind these techniques; showing how conformal, stereotactic therapy is advantageous and why each instance requires complex treatment planning. I will also talk about how this treatment planning is achieved using monte-carlo simulations to model radiation transport, and the different software options to do this.

Graduate Seminar, 21st March

Speaker: Artur Miroszewski

Title: Affine quantization of FRW universe and some cosiderations about semiclassical analysis

Abstract: In my talk I will introduce phenomenological method appropriate to deal with quantum systems originating from classical systems defined on half-plane phase space. In order to use the mentioned method I will present theory of affine coherent states and integral quantization. By applying affine quantization (affine coherent states integral quantization) to FRW universe we will get one of the well estabilished results of quantum cosmology- initial singularity avoidance. By rough semiclassical analysis we will get some properties of the Big Bounce. I will end my talk by presenting some ideas to improve semiclassical analysis by using coherent states.

Graduate Seminar, 14th March

Speaker: Albin Nilsson

Title: Constraining Lorentz Invariance Violating Scenarios in Rainbow Gravity by Cosmological Data

Abstract: The standard relativistic dispersion relation is modified to break Lorentz symmetry, which is predicted in the high-energy regime of certain theories of quantum gravity. We show that is it possible to realise this scenario in the framework of Rainbow Gravity. We also derive the modified Friedmann-Lemaitre-Robertson-Walker (FLRW) equations and show that these lead to a change in the standard expression for luminosity distance. $G$ and $\Lambda$ are assumed to be energy dependent; we give two explicit examples of this and constrain these functions using the Union2.1 Sn1a dataset. We also consider a more general case with an undefined function and obtain constraints on its magnitude.

For more details please see https://arxiv.org/abs/1701.00533

Graduate seminar, 7th March

Speaker: Piotr Warzybok

Title: The 316L steel SLM 3D printing process and the fabricated material physical properties.

Abstract: One of the techniques of additive manufacturing is the SLM (Selective Laser Melting) technology. In this method, an object is created by selectively fusing thin layers of powder using a scanning laser beam according to CAD data of the part. SLM in known since the ‘90s and the recent efforts have improved this technique considerably, but still many problems handicapping the successful fabrication of high-quality metal parts with desired microstructures and properties do exist. Physical phenomena during the process of 3D printed parts will be reviewed. The most important physical parameters of the 3D printed metal models will be discussed. The future goals of my research will be defined.

Graduate seminar, 28th Feb.

Speaker: Grzegorz Żarnecki

Title: My activity in particle physics and plans for PhD studies

Abstract: The presentation will be divided in two major parts: in the first one the Level-1 muon trigger system of the CMS experiment will be introduced. Last year as a member of CMS Warsaw Group I’ve written my master’s thesis on muon selection in the overlap region of the CMS detector. Some basic results from my thesis will be presented. The second part will be focused on neutrino oscillations, as both my Bachelor’s thesis and plans for PhD studies are related to this phenomena. I’ll give some details and results of long baseline neutrino experiments (MINOS/MINOS+ and T2K).

Graduate Seminar Jan. 31st

Speaker: Joanna Reszczyńska

Title: Ionizing Radiation – what is the risk of cancer at low doses?

Abstract: There exists a vast number of studies of biological effects of ionizing radiation, mostly dedicated to radiation-induced cancers. Whereas the field of early effects is quite well understood, the low doses (below, say, 100 mGy) that may at best create only late or very late delatorious effects are a subject of on-going research. Estimation of a cancer risk for low doses or ionizing radiation requires universal biology-based model taking into account essential processes that take place in irradiated cells. I will try to present a relatively simple approach which can show what could be expected for the dose-effect dependence in the colony of cells as well as theoretical background of this subject.