HADES has a large acceptance combined with a good mass-resolution and therefore allows the study of dielectron and hadron production in heavy-ion collisions with unprecedented precision. With the statistics of seven billion Au-Au collisions at 1.23A GeV recorded in 2012, the investigation of higher-order flow harmonics is possible. At the BEVALAC and SIS18 directed and elliptic flow has been measured for pions, charged kaons, protons, neutrons and fragments, but higher-order harmonics have not yet been studied. They provide additional important information on the properties of the dense hadronic medium produced in heavy-ion collisions. We present here a high-statistics, multidifferential measurement of v1 and v2 for protons in Au+Au collisions at 1.23A GeV.

The HADES experiment provides a large acceptance combined with a high mass resolution and therefore makes it possible to study dielectron and hadron production in heavy-ion collisions with unprecedented precision. With the high statistics of seven billion Au+Au collisions at 1.23 AGeV recorded in 2012 the investigation of collective effects and particle correlations is possible with unprecedented accuracy. We present multi-differential data on directed (v1) and elliptic (v2) flow, and the first measurement of triangular flow (v3), of protons and deuterons.

Measurements of collective flow and two-particle correlations have proven to be effective tools for understanding the properties of the system produced in ultrarelativistic nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC). Accurate modeling of the initial conditions of a heavy ion collision is crucial in the interpretation of these results. The anisotropic shape of the initial geometry of heavy ion collisions with finite impact parameter leads to an anisotropic particle production in the azimuthal direction through collective flow of the produced medium. In "head-on" collisions of Copper nuclei at ultrarelativistic energies, the magnitude of this "elliptic flow" has been observed to be significantly large. This is understood to be due to fluctuations in the initial geometry which leads to a significant anisotropy even for most central Cu+Cu collisions. This thesis presents a phenomenological study of the effect of initial geometry fluctuations on two-particle correlations and an experimental measurement of the magnitude of elliptic flow fluctuations which is predicted to be large if initial geometry fluctuations are present. Two-particle correlation measurements in Au+Au collisions at the top RHIC energies have shown that after correction for contributions from elliptic flow, strong azimuthal correlation signals are present at A0 = 0 and A0 ~ 120. These correlation structures may be understood in terms of event-by-event fluctuations which result in a triangular anisotropy in the initial collision geometry of heavy ion collisions, which in turn leads to a triangular anisotropy in particle production. It is observed that similar correlation structures are observed in A Multi-Phase Transport (AMPT) model and are, indeed, found to be driven by the triangular anisotropy in the initial collision geometry. Therefore "triangular flow" may be the appropriate description of these correlation structures in data. The measurement of elliptic flow fluctuations is complicated by the contributions of statistical fluctuations and other two-particle correlations (non-flow correlations) to the observed fluctuations in azimuthal particle anisotropy. New experimental techniques, which crucially rely on the uniquely large coverage of the PHOBOS detector at RHIC, are developed to quantify and correct for these contributions. Relative elliptic flow fluctuations of approximately 30-40% are observed in 6-45% most central Au+Au collisions at s NN= 200 GeV. These results are consistent with the predicted initial geometry fluctuations.

"These proceedings contain selected topics covering various fields of collective motion and nuclear dynamics, ranging from low to high energies, from nuclear structure to reaction mechanisms, from regular stable to chaotic systems, and from fragmentation to fusion. Several ways of investigating the nuclear systems are presented: electron scattering radioactive beams, fragmenting projectiles, beta and double beta decays, and cluster emission. Their behaviour, under some extreme situations such as superdeformation, high spin states, high temperature, and relativisitic energy, is described within various theoretical formalisms."--Publisher's website.