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Diploma/Master

Electron dynamics control via radiation reaction

Next-generation multipetawatt laser systems such as the Extreme Light Infrastructure (ELI) and at the Exawatt Center for Extreme Light Studies(XCELS) are expected to reach intensities beyond 1022 W/cm2 at their focus, paving the way to novel investigations in the realm of ultrastrong-field electrodynamics. At such ultrahigh intensity, for example, an electron undergoes an extreme acceleration and becomes ultrarelativistic in a fraction of the laser period therefore emitting large amounts of electromagnetic radiation. As a consequence, the back-action on the electron's motion of the radiation emitted by the electron itself, namely the radiation reaction force, becomes important, and may noticeably alter the electron dynamics. A deep understanding of RR effects is therefore crucial for the design and the interpretation of experiments at ultrahigh intensities.

In addition, it has been recently shown that the radiation reaction force can be employed to control the electron dynamics in the interaction of an electron colliding head-on with a bichromatic laser laser pulse, by tuning the relative phase between the two frequency components [Tamburini et al., Phys. Rev. E 89, 021201(R) (2014)]. A similar effect is also predicted in the interaction of an electron with a carrier-envelope-controlled superintense laser pulse, such as those that can be generated by employing the relativistic mirror technique [Tamburini et al., Phys. Rev. Lett. 113, 025005 (2014)].

We are seeking a master student to investigate the features of the electron dynamics in the interaction with a carrier-envelope-tunable few-cycle laser pulse. The student is expected to carry out both analytical calculations and numerical simulations starting with an existing code. Fluency in English and a solid background in theoretical physics are required, a sound knowledge of Fortran or C/C++ is desirable.

Please send your application including CV by email to Matteo Tamburini.

Extention of the theory of hyperfine structure of highly charged ions

Project one: Hyperfine structure of muonic atoms and ions

Muonic ions are ions, where one (or, rarely, more) electron is replaced by the muon. In such a system, all the theoretical methods, developed for the highly-charged ions, can be used. That makes muonic ions a comparably easy system to calculate. However, as muonic ions are still quite exotic, they are not so well studied, which gives a lots of possibilities to theoretical research.
 
Muonic ions provide an opportunity to learn more about nuclear properties [NIMB V. 235, P. 65 (2005)]. The larger mass of the muon in comparison to that of the electron (about 200 times bigger) makes such a system very sensitive to the change of the nuclear parameters, and a possible candidate to test or determine these.

In addition to already considered H-like ions, one can pay attention to the Li-like and B-like ions. Mixed ions with both muon and electrons can be also studied. As a case of a special interest, muonic hydrogen can be considered, which can contribute to the explanation of the proton size puzzle.

The study will include both analytical and numerical calculations.

Project two: Hyperfine structure of highly charged ions in external magnetic field

A wide use of HCI in the experiments requires a better knowledge of their behavior. An external magnetic field can be a part of the experimental setup. For example, g-factors of HCI allow one to identify lines in spectrum analysis. Therefore, a general theory of the level structure shifts and splitting in an external magnetic field of different magnitudes can be a subject of consideration. Ground and excited states of HCI with few electrons (for example, H-like, Li-like, B-like ions) can be studied. Furthermore, one may also consider a combined hyperfine and Zeeman splitting effect in ions with nonvanishing nuclear spin.

The study will include both analytical and numerical calculations.

Please send your application including CV by email to Natalia Oreshkina.

Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE)

Next generation of particle acceleration (both electrons and ions) sources heavily rely on employing plasma based acceleration schemes e.g. laser-driven wakefield acceleration, radiation pressure acceleration (RPA), collisionless shock acceleration (CSA) of ions, as plasmas provide an extremely high gradient (few GeV/m) for particle acceleration. Though, the plasma based particle acceleration has demonstrated acceleration in GeV (giga-electron volt) energy regime, particle physics experiments require electrons acceleration in TeV (tera-electron volt) regime. In this context it had been proposed to employ the LHC proton bunch at CERN to excite a strong plasma wakefield and accelerate background plasma electrons to TeV energy range [Caldwell et. al., Nature Physics, 5, 363 (2009)]. However, the LHC proton bunches are long (few cm) and they can not excite a resonant plasma wakefield. It was suggested that a plasma instability namely Self-modulation instability can split the long LHC bunches into smaller parts (few ¿m) and a resonant wakefield can be excited [Kumar et al., Phys. Rev. Lett, 104, 255003 (2010)]. Which has been recently demonstrated in the AWAKE experimental campaigns at CERN [Adli et al., Nature, 561, 363 (2018)].

Notwithstanding the initial success, certain issues remain open towards the path to TeV electron acceleration. This master thesis project is aimed at numerically and theoretically investigating issues such as beam loading, multi-stage beam propagation, and radiation generation associated with the self-modulation instability. For numerical calculations, we use particle-in-cell (PIC) and other codes to model the proton beam propagation in plasmas. Working on this project will provide a good opportunity to learn about the the beam-plasma instabilities relevant for the AWAKE campaign, and the start-of-the-art PIC and numerical codes to simulate beam-plasma interactions. The candidate is expected to carry out both analytical and numerical investigations under adequate guidance. A background knowledge in C/C++, Fortran90 and python/Matlab is desirable.

Please send your application including CV by email to Naveen Kumar.