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Using fly’s eye homogenizer has proven applicability in various fields, ranging from early-stage microscopy to state-of- the-art lithography. Hereby periodic lens arrays are commonly used to form a homogenous top -hat distribution. In turn, this periodicity can limit the attainable homogeneity by interference based micro - inhomogeneities. Furthermore, the positioning of the lens arrays results in small spot sizes directly at the lens surface, compromising functionality for large pulse energies. Here we present the challenges emerging due to the usage of non-periodic lens-arrays and introduce our design concept, suppressing interference based micro-inhomogeneities while being suitable for applications with large pulse energies.

Beam-shaping of homogeneous line profiles at ultra-violet wavelengths has wide applicability in the flat-panel display industry. Besides the well-established Excimer-Laser-based setups, diode-pumped-solid-state lasers with high repetition rates and comparatively small pulse energies have proven to be capable of providing a cost-effective alternative for different process steps e.g. Laser-Lift-Off or Solid-State-Laser-Annealing. We give a short summary about challenges emerging during the design of these system and demonstrate the generation of state-of-the-art laser-lines, offering a super-Gaussian, top-hat-shaped short-axis profile..

In March 2019 the HADES experiment recorded 14 billion Ag+Ag collisions at √sNN = 2.55 GeV as a part of the FAIR phase-0 physics program. In this contribution, we present and investigate our capabilities to reconstruct and analyze weakly decaying strange hadrons and hypernuclei emerging from these collisions. The focus is put on measuring the mean lifetimes of these particles.

The STAR collaboration has installed three detector upgrades for the beam energy scan phase II program at RHIC to aid the exploration of the QCD phase diagram. After BES-II the forward upgrade of STAR will enable novel measurements in pp, pA and AA collisions motivated by cold QCD and heavy-ion physics. Results from the commissioning of the new detectors and their performance during the first year of running in BES-II will be discussed together with the general progress of BES-II and the status of the forward upgrade.

The search for a first-order phase transition in strongly interacting matter is one of the major objectives in the exploration of the phase diagram of Quantum Chromodynamics (QCD). In the present work we investigate dilepton radiation from the hot and dense fireballs created in Au-Au collisions at projectile energies of 1-2 $A$GeV for potential signatures of a first-order transition. Toward this end, we employ a hydrodynamic simulation with two different equations of state, with and without a phase transition. The latter is constrained by susceptibilities at vanishing chemical potential from lattice-QCD as well as neutron star properties, while the former is implemented via modification of the mean-fields in the quark phase. We find that the latent heat involved in the first-order transition leads to a substantial increase in the low-mass thermal emission signal, by about a factor of two above the cross-over scenario., Comment: 14 pages, 8 figures

Dielectrons are ideal probes of the hot and dense medium created in relativistic heavy-ion collisions due to their minimal interactions with the partonic and hadronic medium. They carry the information from the initial to the final stage of a collision. We present the dielectron spectra in Au+Au collisions at s NN = 27 , 54.4 and 200 GeV measured with the STAR experiment. The large minimum bias datasets at s NN = 27 ( 54.4 ) GeV taken in 2017 (2018) significantly enhance the precision of the in-medium ρ modification measurement compared to previous STAR BES-I results. The Heavy Flavor Tracker (HFT) installed at STAR between 2014 and 2016 enables a better understanding of the semi-leptonic charm decay contributions by providing high-precision tracking and vertex information. Strategies to extract the dielectron spectra and suppress the charm component to the spectrum with the HFT in s NN = 200 GeV Au+Au collisions are discussed.

We present an inline measurement technique for the phase difference between two transverse fiber modes. This technique proves to be well suited for direct measurement of an all-optically changed phase difference between two transverse modes of picosecond probe pulses, induced via intermodal cross-phase modulation by co-propagating picosecond control pulses. We achieved unprecedented agreement with the corresponding analytical description for time-independent changes of the phase difference as well as for time-dependent changes on an intra-pulse timescale. The simple and accurate predictability combined with the ability to measure modal phase differences inline poses a key step towards full all-optical control over transverse modes in fibers. This may lead the way to a variety of novel functionalities for all-fiber applications, like a spatial degree of freedom in fiber-sensing technology by using transverse fiber modes or all-optical spatial and temporal pulse shaping inside a fiber.

Electromagnetic radiation is emitted during the whole course of a heavy-ion collision and can escape from the collision zone without further interactions. This makes it an ideal tool to study the properties of hot and dense QCD matter. To model the space-time evolution of the collision at SIS energies a coarse-graining approach is used to convert transport simulations into meaningful temperatures and densities. These parameters serve as input for the determination of the pertinent radiation of thermal dileptons based on an in-medium $\rho$ spectral function that describes available spectra at ultrarelativistic collision energies. The resulting excitation function of the thermal excess radiation provides a baseline for future measurements by the HADES and CBM experiments at GSI/FAIR, and experiments proposed at NICA and J-PARC., Comment: 5 pages, 5 figures, contribution to FAIRness 2017 - FAIR next generation scientists - 5th Edition Workshop (May 28, 2017 to June 3, 2017 in Sitges, Spain)

Utilizing a coarse-graining method to convert hadronic transport simulations of Au+Au collisions at SIS energies into local temperature, baryon and pion densities, we compute the pertinent radiation of thermal dileptons based on an in-medium $\rho$ spectral function that describes available spectra at ultrarelativistic collision energies. In particular, we analyze how far the resulting yields and slopes of the invariant-mass spectra can probe the lifetime and temperatures of the fireball. We find that dilepton radiation sets in after the initial overlap phase of the colliding nuclei of about 7 fm/c, and lasts for about 13 fm/c. This duration closely coincides with the development of the transverse collectivity of the baryons, thus establishing a direct correlation between hadronic collective effects and thermal EM radiation, and supporting a near local equilibration of the system. This fireball "lifetime" is substantially smaller than the typical 20-30 fm/c that naive considerations of the density evolution alone would suggest. We furthermore find that the total dilepton yield radiated into the invariant-mass window of $M=0.3-0.7$ GeV/$c^{2}$, normalized to the number of charged pions, follows a relation to the lifetime found earlier in the (ultra-) relativistic regime of heavy-ion collisions, and thus corroborates the versatility of this tool. The spectral slopes of the invariant-mass spectra above the $\phi$ mass provide a thermometer of the hottest phases of the collision, and agree well with the maximal temperatures extracted from the coarse-grained hadron spectra., Comment: 9 pages, 6 figures; v2: extended discussion, matches the version accepted for publication