Mihály András Pocsai (2021.10.01 - 2022.01.31)
Wigner Research Centre for Physics
Abstract: In the concept of plasma based particle acceleration, the particles are accelerated in the wakefield generated by a driver pulse, which may be either a beam of charged particles or a short, intense laser pulse, instead of guiding,collimating and them in vacuum with strong electromagnetic fields . The witness bunch is usually injected in the plasma from an external source, but in case of electron acceleration using a laser pulse as a driver pulse, at sufficiently high laser intensities, some of the plasma electrons are being trapped in the wakefield generated by the laser pulse. This phenomenon is referred as self-injection. In the schemes mentioned above, the driver bunches transfer their energy to the witness bunches through the plasma waves they generate. In the CERN–AWAKE experiment the...
Emese Forgács-Dajka, László Dobos, István Ballai (2021.05.01-2021.11.31)
Eötvös Loránd University, John Hopkins University and Sheffield University
Abstract: Observing the phenomena of solar activity has a long history, so we have the opportunity to study on a long time scale. We aim to study the time dependence of sunspot group areas in a large sample composed of various databases spanning over 130 years, used state-of-the-art statistical methods. For a carefully selected but unbiased sample, we use Bayesian modelling to fit the temporal evolution of the combined umbral and penumbral area of spot groups with a skew-normal function to determine the existence of any asymmetry in spot growth or decay. The great advantage of this method is that we can obtain the properties for the whole lifetime (eg lifetime, different parts of the developmental stages, such as growth and decay part) for which there are no complete data sets from appearance to disappearance. The reason for this is to be found in the observation, i.e. due to the rotation of the Sun. Our results robustly support our hypothesis that there are two types of groups: (i) one that develops rapidly after appearance but decomposes more slowly, and (ii) one that grows more slowly and decays faster. In addition, we used the model parameters to examine the lifetime of the sunspot groups and the relationships between lifetime and maximum area.
Time-dependent properties of sunspot groups. I. Lifetime and asymmetric evolution E. Forgacs-Dajka, L. Dobos, I. Ballai A&A, Forthcoming article Received: 05 March 2021 / Accepted: 28 May 2021 DOI: https://doi.org/10.1051/0004-6361/202140731
Gábor Bíró, Bence Tanko-Bartalis (2021. 07. – 2021. 09.)
Wigner Research Centre for Physics and Oxford University
Abstract: The main goal of the project is the application of machine learning methods to improve the study of high-energy particle physics. In high-energy physics there are many different numerical simulations that require significant computational resources, such as the Monte Carlo event generators. The development and testing of these algorithms can be greatly improved with machine learning techniques.
Sudár Ákos, Varga-Kőfaragó Mónika, Barnaföldi Gergely Gábor és Légrády Dávid (2021.07.01 - 09.30)
Wigner Research Centre for Physics és BME Institute of Nuclear Techniques
Abstract: The goal of development of proton computed tomography is the accurate measurement of the relative stopping power (RSP) distribution of the patient, which is necessary to reduce safety zones around the tumor in proton therapy. During the pCT imaging the patient is imaged by protons, which has determined direction and energy before they go into the patient, and their direction and energy is measured after they come out of the patient. From this information the most likely path (MLP) and the energy deposition in the patient can be determined. The 3D image is reconstructed from the measured data with the use of order suppressed expectation maximalization (OSEM) algorithm, which is an accelerated version of maximum likelihood expectation maximalization (ML-EM) algorithm. The goal of the current project is to develop an image reconstruction code, which runs in parallel threads of CPU and use GPU as well to minimize the image reconstruction time. This software will be used in the future to reconstruct the measured data of a pCT detector developed by the Bergen pCT Collaboration. This work would be contribution to the work of the group and their later publications.
Gábor Bíró, Dr. Gábor Papp, Dr. Gergely Gábor Barnaföldi, Balázs Majoros (2021. 06. – 2021. 12.)
Wigner Research Centre for Physics and Eötvös University
Abstract: At the world largest particle accelerators such as the Large Hadron Collider at CERN or the Relativistic Heavy Ion Collider at BNL, hundreds of thousands of interesting interactions may occur in every second. A special subset of these events are the high-energy heavy-ion collisions, aiming to investigate the birth of the Universe itself. These experimental measurements are always accompanied by numerical calculations, such as Monte Carlo event generators. However, these calculations are computationally very intensive: even with a state-of-the-art desktop machine many CPU hours (days, weeks sometimes) are needed to simulate only a few seconds of real experimental data. Additionally, with the future improvements of the LHC it will be an even bigger challenge to catch up computationally. The HIJING++ framework is the next generation of high-energy heavy-ion Monte Carlo event generators. Equipped with the latest theoretical models, it is designed to perform precise calculations in a flexible, fast, CPU parallel way. Using multicore architectures, a decent speedup can be achieved, reducing the necessary computational time and the additional costs as well.
Dr. Papp Gábor (ELTE), Bíró Gábor (Wigner FK), Feiyi Liu (ELTE), Xiangna Chen (CCNU, Wuhan), Dudás Bence (ELTE), Misur Patricia (ELTE) (2021.06.01-08.31)
Abstract: One effective way to kill localized cancerous tumors that are not accessible by surgery is radiation treatment with a proton (or heavier ions as He or C, respectively). In the process, one treatment is usually sufficient compared to conventional radiation therapy, since the proton is very well focused, (with an accuracy of 1 mm, heavier ions with even greater accuracy). However, because the in matter penetration profiles of proton and gamma rays are different, CT tomography does not calibrate the proton beam and does not allow accurate device alignment, resulting in practice in treatment that is far less accurate than the theoretical limit. Greater accuracy can be achieved by proton tomography using a proton beam used for treatment at a higher energy. To detect particles passing through the patient, we developed a detector system based on ALPIDE chips and CERN technology in the framework of the international pCT collaboration (https://wiki.uib.no/pct/index.php/Main_Page). Because processing of the detector signals is a time-consuming process, we want to speed it up by using a neural network: the goal is to develop and train a neural network that can tell the direction and energy of protons leaving the body based on detector signals. By measuring these at several angles, a tomographic image of the examined area can be obtained and the data required for the treatment can be calculated.
David Legrady, Gabor Tolnai, Tamas Hajas (2021.06.01 - 08.31)
BME Institute of Nuclear Techniques
Abstract: The GUARDYAN (GPU Assisted Reactor Dynamic Analysis, developed at BME Institute of Nuclear Techniques) Monte Carlo code directly follows the time evolution of the neutron field in a nuclear reactor. Contrary to the conventionally applied deterministic (i.e. non-Monte Carlo) or Monte-Carlo based techniques relying on quasistatic approximations modelling errors are minimal for GUARDYAN. For a fast evolving („hard”), localized transients even the magnitude of the modelling errors posed by conventional techniques can hardly be estimated, and experimental confirmation due to nuclear hazards is out of question. Therefore, simulations with GUARDYAN could be set as a gold standard for other computational methods. The project aims at the simulation of a rod ejection transient in a full...
Ernő Dávid, Dávid El-Saig, Zoltán Lehóczky and Gergely Gábor Barnaföldi (2020.12.01 - 2021.11.31)
Wigner RCP and Lombiq Technologies Ltd. cooperation
Abstract: Hastlayer by Lombiq Technologies allows software developers of the .NET platform to utilize FPGAs as compute accelerators. It converts standard .NET constructs into equivalent hardware implementations, automatically enhancing the performance while lowering the power consumption of suitable algorithms. Developers keep writing .NET programs as usual, no hardware design knowledge is required.
Hastlayer needs dedicated firmware and software components for each supported hardware platforms. In collaboration with Wigner RC there are already several supported platforms (like Microsoft Catapult cards and the Xilinx Alveo FPGA card family). The aim of the next development phase is to enable Hastlayer support for embedded platforms like FPGA cards based on the Xilinx Zynq family members.
Wigner's task is to develop the necessary firmware framework to run the Hastlayer-generated hardware cores and if there is a need then customize the Linux operating system running on the embedded ARM CPU cores.
Emese Forgács-Dajka*, István Balla** (2021.05.01-2021.11.31)
* Eötvös University, Dept. of Astronomy ** Solar Physics and Space Plasma Research Centre (SP2RC), Department of Applied Mathematics, The University of Sheffield
Abstract: We investigate the nature and properties of shock waves propagating in an oblique direction to the ambient magnetic field in a partially ionised plasma modelling the plasma of solar prominences. In particular, we aim to analyse the observational signature of these shocks and investigate how our results can explain the recent observations of propagating bright blobs in solar prominences by Lin et al. (2012).
The equations of compressional single-fluid magnetohydrodynamic (MHD) equations are reduced with the help of a multiple scaling method to a well-known Burgers equation whose coefficients depend on the propagation angle of shock waves, plasma-β and the ionisation degree of the plasma. Our model is well-adapted for the separate discussion of shock waves arising from the nonlinear steepening of slow or fast magnetoacoustic waves. Using the standard jump conditions across the shock front (assuming a weak dissipation) we determine the jump in thermodynamic quantities that will be useful for comparison with observations.
Using the Cole-Hopf transform we solve the governing equation as an initial value problem of a diffusion-like equation and investigate the time necessary for a Gaussian initial wave profile to evolve into a shock, whose thickness is of the order of a few ion mean free path.
István Papp, Larissa Bravina, Mária Csete, Igor N. Mishustin, Dénes Molnár, Anton Motornenko, Leonid M. Satarov, Horst Stöcker, Daniel D. Strottman, András Szenes, Dávid Vass, Tamás S. Biró, László P. Csernai, Norbert Kroó (2020.10.16 - 2021.12.31)
Publication: Laser Wake Field Collider
Abstract: Inertial Confinement Fusion is a promising option to provide massive, clean, and affordable energy for humanity in the future. The present status of research and development is hindered by hydrodynamic instabilities occurring at the intense compression of the target fuel by energetic laser beams. NAno-Plasmonic, Laser Inertial Fusion Experiments (NAPLIFE) were proposed, as an improved way to achieve laser driven fusion. The improvement is the combination of two basic research discoveries:
(i) The possibility of detonations on space-time hyper-surfaces with time-like normal (i.e. simultaneous detonation in a whole volume) and
(ii) to increase this volume to the whole target, by regulating the laser light absorption using nano-shells or nano-rods as antennas .
These principles can be realized in an in-line, one dimensional configuration, in the simplest way with two opposing laser beams as in particle colliders . Such, opposing laser beam experiments were also performed recently. Here we study the consequences of the Laser Wake Field Acceleration (LWFA) if we experience it in a colliding laser beam set up. These studies can be applied to laser driven fusion, but also to other rapid phase transition, combustion, or ignition studies in other materials.
 L. P. Csernai and D. D. Strottman, “Volume ignition via time-like detonation in pellet fusion,” Laser Part. Beams. 33 (2), 279--282 (2015).
 L. P. Csernai, N. Kroo, and I. Papp, “Radiation dominated implosion with nano--plasmonics,” Laser Part. Beams. 36 (2), 171--178 (2018).
 L.P Csernai, M. Csete, I.N. Mishustin, A. Motornenko, I. Papp, L.M. Starov, H. Stöcker, N. Kroó, "Radiation dominated implosion with flat target", Physics of Wave Phenomena, 2020, accepted for publication.