20 SEP 2021
11:00 - 12:00

Abstract: Due to the recent growth in applications of microwave energy in science and industry, the necessity to increase the efficiency of microwave amplifiers is essential than ever. Using a multi-beam design Instead of a single beam is a solution to increase the efficiency of the klystron amplifier. Also, the optimal design of the cavities to get the maximum value of the R/Q ratio can increase the efficiency of the klystron and reduce its circuit length in specific output power. The geometric characteristics of the cavities are the only effective parameters on the R/Q ratio. Furthermore, in the extraction cavity, the asymmetry of the electric field's distribution due to output coupling reduces the overall efficiency. This research has investigated the optimal design of a forty beam klystron's extraction cavity and study the effective parameters on its efficiency.


https://meet.google.com/srr-tnnx-gjs

15 SEP 2021
11:00 - 12:00

Abstract: Recently, the excited nuclei, while inserted into materials, have been delivering important information on the physical properties of crystals. For achieving this information, we have to find the exact position of radioactive ionic probes in the lattice and the nature of defects around probes, which is not possible investigated with conventional characterization techniques. In particular, techniques such as perturbed angular correlation (PAC), and emission Mössbauer spectroscopy are outstanding examples of used experimental methods. They can provide detailed information on phase transition, hyperfine fields, lattice location in different types of materials. In addition, The use of perturbed angular correlation (PAC) experiments combined with simulations in the DFT framework provide a unique tool to support the interpretation of experimental data at the atomic scale. The significant interest in these experiments encourages academic and industrial centers to construct robust and sophisticated spectrometry measurement facilities rather than conventional offline measurement techniques. One of the big centers that produce different online radioactive isotopes is ISOLDE/CERN for material sciences. In this talk, I will present the production process of radioactive ions and doing PAC experiments at ISOLDE and I will tell one example of using the numerical method to study the physics behind of ionic probes inside the semiconductors.


Indico: https://indico.particles.ipm.ir/indico/event/426
https://meet.google.com/srb-pwrc-jwz

15 SEP 2021
13:30 - 15:00

The increasing volume, diversity, and role of data in modern research has been very fruitful. However, these same factors, have also made it harder to describe (in sufficient detail) the processing behind a scientific result within the confines of a traditional paper. It is thus becoming harder and harder to reproduce results (i.e., critically review by coauthors, referees or larger community) that define scientific progress. In this talk, Maneage (MANaging data linEAGE) is introduced as a working solution to this problem. Maneage is (a template) that provides a framework to exactly reproduce a scientific analysis (from the input data and software, to the processing and creation of final report/paper/dataset. The necessary software are built (from the low-level C compiler and shell, to the higher-level science programs and all their dependencies) with the predefined configuration. The software are then run on the input data sets to produce the final result. The template will finally produce a "dynamic" PDF using LaTeX macros: any change in the analysis will automatically update the relevant parts of the PDF (for example numbers, tables or figures). A project defined in this template is fully managed and published in plain text and only consumes a few hundred kilo-bytes (unlike binary multi-gigabyte blobs like containers). It is thus easily to publish, for example on arXiv with the paper's LaTeX source or Software Heritage. Giving readers the ability to exactly study and reproduce the paper's results. It is also easily search-able, providing a treasure trove to extract metadata on the project (even after publication, and without the author's active involvement). This can be very valuable when implement widely (e.g., using machine learning on many project sources to define automatic workflows). But most importantly it will allow other scientists to independently study the details, verify in practice, and build incrementally on each others' work, without necessarily needing to run it.

15 SEP 2021
14:00 - 15:00

Abstract:
The classical Hall effect in its textbook form is nothing but the creation of transverse resistance in the presence of a magnetic field due to Lorentz force. However, after the discovery of new versions of the Hall effect with quantum natures, it has become a cornerstone in studying quantum condensed matter. Recently and motivated by theoretical predictions of the nonlinear Hall effect (NLHE) due to the Berry curvature dipole, an endeavor has been started to search for materials with time-reversal symmetry (TRS) but without inverse symmetry. In this talk, after a brief introduction to the NLHE in time-reversal-invariant systems, I will introduce a different yet simple model for engineering NLHE in the presence of a periodic magnetic profile. In this model which lacks TRS, the effect largely stems from boundary states associated with the real-space magnetic dipole. I will also talk about the parametric resonance feature of the effect, involving the cyclotron ratio and characteristic widths of the magnetic profile, which can greatly enhance the nonlinear Hall signal.



Date: Wednesday, September 15, 2021

Time: 14:00-15:00

To join the webinar, please follow this link:
https://www.skyroom.online/ch/schoolofphysics/condensed-matter-and-statistical-physics
and log in as guest.

Organized by: Condensed Matter and Statistical Physics Group, School of Physics (IPM)

Queries about this event should be addressed to Dr. A. Faridi at azadeh.faridi@ipm.ir

15 SEP 2021
14:00 - 15:00

The classical Hall effect in its textbook form is nothing but the creation of transverse resistance in the presence of a magnetic field due to Lorentz force. However, after the discovery of new versions of the Hall effect with quantum natures, it has become a cornerstone in studying quantum condensed matter. Recently and motivated by theoretical predictions of the nonlinear Hall effect (NLHE) due to the Berry curvature dipole, an endeavor has been started to search for materials with time-reversal symmetry (TRS) but without inverse symmetry. In this talk, after a brief introduction to the NLHE in time-reversal-invariant systems, I will introduce a different yet simple model for engineering NLHE in the presence of a periodic magnetic profile. In this model which lacks TRS, the effect largely stems from boundary states associated with the real-space magnetic dipole. I will also talk about the parametric resonance feature of the effect, involving the cyclotron ratio and characteristic widths of the magnetic profile, which can greatly enhance the nonlinear Hall signal.

14 SEP 2021
17:00 - 18:00

Abstract: Understanding the fate of semi-classical black hole solutions at very late times is one of the most important open questions in quantum gravity. In this talk, we provide a path integral definition of the volume of the black hole interior and study it at arbitrarily late times for black holes in various models of two-dimensional gravity. Because of a novel universal cancellation between the contributions of the semi-classical black hole spectrum and some of its non-perturbative corrections, we find that, after a linear growth at early times, the length of the interior saturates at a time, and towards a value, that is exponentially large in the entropy of the black hole. This provides a non-perturbative confirmation of the complexity equals volume proposal since complexity is also expected to plateau at the same value and at the same time.
( for participating in this event, please contact us: "particles@ipm.ir" )