Topics for 2017:
- High-intensity laser-plasma ion generation is promising as a compact, low-cost proton source for applications like ion beam therapy. Using femtosecond table-top laser systems, very intense ion bunches are generated by relativistic laser-plasma interaction in a microscopic volume. For envisaged medical applications predominantly the particle energy has to be further increased, which in our group is currently addressed by investigating novel acceleration mechanisms, targetry and ongoing development of the high power laser system.
- OpenStack integration in das High Performance Computing: OpenStack is an open source Infrastructure as a Service (IaaS) platform used to support the needs of researchers to work with different virtualized environments which is commonly known as cloud computing. The aim of this topic is to develop a base concept how to set up virtual HPC environments and to evaluate such an OpenStack environment in terms of usability, stability and performance.
The project will deal with radiation transport simulations using Monte Carlo techniques. These simulations are needed to evaluate shielding requirements and/or improve the understanding of experimental conditions. During the course of the program, the student will learn how to create a geometrical model of the corresponding experiment or facility, how to implement the primary radiation sources as well as the underlying physics processes, and how to extract, analyze and interpret the results from the simulation output.
Antiferromagnetic materials are magnetically ordered similar to the more well-known ferromagnets, but possess an internal magnetic arrangement which leads to zero net magnetization. Devices based on antiferromagnets have the potential to operate at substantially higher frequencies and at enhanced power efficiency when compared to conventional spintronic concepts. Historically, these materials were difficult to probe requiring large scale facilities and applications were limited as a consequence. Recently, a new all-electric characterization method called Zero-Offset Hall was developed in our group. This fascinating approach makes it possible to study antiferromagnetic thin films in the laboratory and provides an electronic interface for prospective spintronic devices. Many previously phenomenological models are thus now open to experimental scrutiny. At the same time, entirely new investigation schemes are currently being developed fueled by the extended accuracy of the Zero-Offset Hall technique. The direct and quick lab-based access to materials allows fast iterations in terms of material optimization for applications in antiferromagnetic spintronics. Precision measurements may hold the key to unravel yet unknown effects due its unparalleled sensitivity to tiny magnetization and to more exotic quantities like the topological charge. For such precision measurements, the experiments go hand-in-hand with sophisticated data analysis concepts encompassing filtering algorithms and statistics.
Theory of Laser-Matter interaction at ultra-high intensities: We study the interaction of ultra-intense, ultra-short laser pulses with matter. Our research spans from the fundamental dynamics of electrons and ions in ultra-intense fields and laser-driven plasmas to applications of laser-driven particle and radiation beams for cancer therapy and X-ray lasers. In our group we develop and use adavnced simulation techniques to study these phenomena.
- Investigating the Magnetization Dynamics in Nanostructures: We use ferromagnetic resonance to study the magnetic properties of novel nanostructures. These can be magnetic blocks, rods or even tubes. These structures offer unique properties like symmetry breaking otherwise not found in thin films. In addition, periodic nanostructures allow access to spin wave properties. The student will be integrated into the magnetization dynamics group performing FMR experiments, data analysis, and sample preparation.
- During the first three minutes of the universe, the 2H(p,gamma)3He reaction transforms deuterium to helium-3. This nuclear reaction is currently the most important uncertainty for the predicted deuterium abundance from Big Bang nucleosynthesis (BBN). Its cross section is now being measured at the LUNA underground accelerator, Italy. The summer student shall calculate the thermonuclear reaction rate from preliminary new cross section data. Subsequently, she/he shall use available BBN codes in order to develop new constraints on the primordial baryon-to-photon ratio.
- Conventional electronics has ignored the election spin. We are focused on studying the interaction of spin-polarised currents on magnetisation and magnetisation dynamics. The main focus of the spintronics group at the IBC is exploit this interaction to generate a new wireless communication device which operates in the THz regime, and can be up to 1000 times faster than conventional wireless communications (GSM, WLAN etc.). This requires understanding of the fundamental physics and the requirements of real-world devices.
Our group is exploring the application of magnons in magnetic nanostructures for data transport and processing. Our research involves nano fabrication, magneto-transport measurements and various magneto-optical spectroscopy tools. We involve summer students in all parts of our scientific work from electron beam lithography reaching to magnon spectroscopy using Brillouin light scattering microscopy and time resolved Kerr spectroscopy.
- Investigation of ultrafast optical switch for free-electron laser: An ultrafast optical switch is a device which can be triggered from a transparent into a highly reflective state within less than 1 picosecond. It is planned to be used inside the cavity of the infrared free-electron laser FELBE in order to dump out ultrashort terahertz pulses with megawatt peak power. In frames of this project, the optically-driven switching of various samples will be tested using a compact table-top terahertz source in a optical lab at the ELBE accelerator. The goal is to find the best candidate to the optical switch which shows a high switching contrast, a high damage threshold and a fast response time.
- Hyperdoping by non-equilibrium processing for extended infrared Si p-n photodiodes: The development of room-temperature extended infrared Si photodetectors is of great interest for integrated photonics, optical communications, sensing and medical imaging applications.The typical peak photoresponse of traditional Si photodetectors is between 700 and 900 nm, which is mostly limited by the 1.12 eV-Si indirect band gap. Nevertheless, such intrinsic material limitation can be circumvented by introducing transition metals or chalcogens into the Si band gap at concentrations far above those obtained at equilibrium conditions. Ion implantation and short-time annealing have been the adopted methods in those approaches. This new class of hyperdoped materials with a donor impurity band has been postulated as a promising route to extend the Si photoresponse at the short-wavelength infrared spectral region.
The Helium Ion Microscopy group at the ion Beam Center focuses on the development of new laterally resolved methods for ion beam analysis using focused ion beams. However, we also apply these new and established methods to answer a wide range of nanoscale materials questions. A particular interest lies on understanding changes in the materials behavior when the scale of the feature of interest is scaled down to the nanometer range. Topics include but are not limited to understanding nanostructure formation, development of surface patterns, damage accumulation as well as the design and characterization of new detectors.
The project is focused on exploiting the several binary alloys (like FeRh andFeAl) sensitivity to structural disorder induced by ion implantation. The control over the magnetization with ion beam treatment offers the unique possibility to fabricate the ferromagnetic micro- and nanosctructures embedded in thin films, which are perspective working elements for many emerging electronic technologies. Using the institute-foundational facilities for ion irradiation the invited summer student will carry on the simulation and experiments on patterning the individual ferromagnetic nanostructures and investigate their structural and magnetic properties with in-house laboratory equipment (X-ray diffraction, atomic/magnetic force microscopy, Kerr microscopy, SQUID magnetometry).
- We offer a Summerstudent position in the magnetism division at the Institute of Ion Beam Physics and Materials Research.The student will work with a group of scientist who focused their scientific work on nanoscience, in particular on ferromagnetic resonance (FMR) and scattering measurements on novel magnetic nanostructures.The scientific goal of the project is an investigation of highly ordered nanoparticle superlattices, which are a new class of materials. We are interested in their structural and magnetic properties. The main task will be the magnetic investigation of the system by ferromagnetic resonance (FMR). Concerning this, the student has the chance to join the microresonators production by lithography, perform the FMR experiments and data analysis. The microresonators are the measurement tool allowing us to detect smallest objects by FMR to characterize the magnetization dynamics of nano objects.
- Magnetic materials become more significant for future data storage devices and spintronic applications. In this project alloy thin films will be modified using focused ion beams as well as broad beams. You will learn how to grow thin films (e.g. FeAl) using magnetron sputtering. Different methods will be applied to characterize the magnetic, structural as well as transport properties of these films.
Accelerator Mass Spectrometry (AMS) allows single atom counting of very rare long-lived radionuclides. Besides established applications in geoscience and archaeometry, astrophysical applications have recently come into focus: The search for supernova signatures on Earth and the determination of nuclear reaction rates for improved stellar evolution and nucleosynthesis models. The summer student will be involved in such an astrophysical AMS project.
Application of advanced simulation tools for safety analyses of nuclear reactors: Accurate prediction of nuclear reactor behavior under different conditions is an important task in reactor safety analyses which heavily depends on the availability of sophisticated computer simulation codes. Currently, nuclear power reactors of a PWR (Pressurized Water Reactor) type dominate the fleet of operating nuclear power reactors in Germany and worldwide. During the summer stay a student will simulate the behavior of a realistic PWR. A student will apply advanced reactor simulation tools including 3D core simulator DYN3D developed at HZDR. A student will get familiar with the basics of nuclear reactor design and operation, the advances and challenges in nuclear reactor analyses, as well as acquire a practical experience in the modeling and simulation of nuclear reactors.
Super-SIMS for mineralogical applications: The coupling of a Secondary Ion Mass Spectrometer (SIMS) with a Tandem Accelerator will allow laterally resolved analysisi of minerals in the ultra-trace elemenet level (< 1 ppb for ideal matrix - analyte combinations.). The summer student will be involved in the development of these challenging but exciting new analytical capabilities.
Ion irradiation of steel causes hardening and embrittlement as a consequence of the formation of various crystal structure defects such as dislocation loops, voids and nano-clusters. The knowledge about size, spatial distribution and the nature (e.g. Burgers vector) of those defects is indispensable for the understanding of irradiation hardening on a microscopic level. We employ Transmission Electron Microscopy (TEM) as a unique technique for the local measurement of these quantities at sub-nanometre spatial resolution. Especially, dislocation loops are investigated by means of the so called "weak-beam dark-field" method, which suppresses the matrix contrast and emphasizes the defective areas in irradiated samples. Fundamentally, the formation of defect contrast in the images is based on the strong electrostatic interaction between the beam electrons and the atomic potentials. The dynamic nature of electron scattering, however, often prohibits a direct interpretation of the acquired images, which makes imaging simulations necessary for interpretation.
Tasks for the summer student: For given structure models, the student simulates the electron scattering process as the fundamental mechanism for the formation of images of dislocation loops as measured by means of TEM. Based on simplifying assumptions, the quantum mechanical scattering problem can be described by a system of ordinary differential equations and will be numerically solved by the student. As a consequence of the dynamic nature of the scattering process, we expect the measured size and position of the defects to be strongly dependent on the orientation of the sample relative to the direction of the incident electron beam and further microscope parameters. The student is expected to possess a certain affinity to theoretical and computational questions. Depending on the interest and capabilities of the student, systematic comparisons to real experimental TEM-results are envisaged.