The fabrication of highly reflective aluminum coatings is still an important part of current research due to their high intrinsic reflectivity in a broad spectral range. By using thin seed layers of Cu, CuOx, Cr, CrOx, Au, and Ag, the morphology of sputtered (unprotected) aluminum layers and, consequently, their reflectance can be influenced. In this long-term study, the reflectance behavior was measured continuously using spectrophotometry. Particular seed layer materials enhance the reflectance of aluminum coatings significantly and reduce their long-term degradation. Combining such seed layers with evaporation processes and suitable protective layers could further increase the reflectance of aluminum coatings.

Three-nucleon (3N) forces are an indispensable ingredient for accurate few-body and many-body nuclear structure and reaction theory calculations. While the direct implementation of chiral 3N forces can be technically very challenging, a simpler approach is given by employing instead a medium-dependent NN interaction V_med that reflects the physics of three-body forces at the two-body normal-ordered approximation. We review the derivation and construction of V_med from the chiral 3N interaction at next-to-next-to-leading order (N2LO), consisting of a long-range $2\pi$-exchange term, a mid-range $1\pi$-exchange component and a short-range contact term. Several applications of V_med to the equation of state of cold nuclear and neutron matter, the nucleon single-particle potential in nuclear matter, and the nuclear quasiparticle interaction are discussed. We also explore differences in using local vs. nonlocal regulating functions on 3N forces and make direct comparisons to exact results at low order in perturbation theory expansions for the equation of state and single-particle potential. We end with a discussion and numerical calculation of the in-medium NN potential V_med from the next-to-next-to-next-to-leading order (N3LO) chiral 3N force, which consists of a series of long-range and short-range terms.

Mammographic breast density is an important risk marker in breast cancer screening. The ACR BI-RADS guidelines (5th ed.) define four breast density categories that can be dichotomized by the two super-classes dense" and not dense". Due to the qualitative description of the categories, density assessment by radiologists is characterized by a high inter-observer variability. To quantify this variability, we compute the overall percentage agreement (OPA) and Cohen's kappa of 32 radiologists to the panel majority vote based on the two super-classes. Further, we analyze the OPA between individual radiologists and compare the performances to an automated assessment via a convolutional neural network (CNN). The data used for evaluation contains 600 breast cancer screening examinations with four views each. The CNN was designed to take all views of an examination as input and trained on a dataset with 7186 cases to output one of the two super-classes. The highest agreement to the panel majority vote (PMV) achieved by a single radiologist is 99%, the lowest score is 71% with a mean of 89%. The OPA of two individual radiologists ranges from a maximum of 97.5% to a minimum of 50.5% with a mean of 83%. Cohen's kappa values of radiologists to the PMV range from 0.97 to 0.47 with a mean of 0.77. The presented algorithm reaches an OPA to all 32 radiologists of 88% and a kappa of 0.75. Our results show that inter-observer variability for breast density assessment is high even if the problem is reduced to two categories and that our convolutional neural network can provide labelling comparable to an average radiologist. We also discuss how to deal with automated classification methods for subjective tasks.

The behavior of the collective rotor in the chiral motion of triaxially deformed nuclei is investigated using the particle rotor model by transforming the wave functions from the K representation to the R representation. The energy spectra of the doublet bands and their energy differences as functions of the triaxial deformation are first examined and then the angular momentum components of the rotor, proton, neutron, and the total system are investigated. Moreover, the probability distributions of the rotor angular momentum (R plots) and their projections onto the three principal axes (K-R plots) are analyzed. The evolution of the chiral mode from a chiral vibration at the low spins to a chiral rotation at high spins is illustrated at triaxial deformations gamma = 20 degrees and 30 degrees.

For ground- and spaced-based applications, Ag-coated reflectors are indispensable because of their high reflectivity. The transport, assembly, and storage of these reflectors take places over a long period before they are finally commissioned for application. To endure this period without a decrease of reflectivity, protective coatings with a final layer, which offers a high resistance to aqueous solutions, and a low mechanical stress should be used. These criteria were taken into account for the selection of a final layer for a protected Ag coating, which was applied for reflectors utilized in the CRIRES+-instrument (an IR spectrograph used at the VLT). Reactively sputtered Al2O3, SiO2 and Si3N4 layers were investigated with regard to these criteria. In aqueous (alkaline) solutions, the investigated Si3N4 layers are more stable than the SiO2 layers and the SiO2 layers more stable than the Al2O3 layers. This shows the influence of the intrinsic material properties. The mechanical stress of the sputtered layers depends on the deposition conditions and thus on the selected parameters. A Si3N4 layer with a high resistance to aqueous (alkaline) solutions also offers low and stable mechanical stress. Therefore, the deposition parameters used for this layer were applied for sputtering the final layer of the protected Ag coating for the reflectors.

We derive from the subleading contributions to the chiral three-nucleon force (long-range terms, published in Phys.\,Rev.\,C\,77, 064004 (2008)) a density-dependent two-nucleon interaction $V_\text{med}$ in isospin-symmetric, spin-saturated nuclear matter. Following the division of the pertinent 3N-diagrams into two-pion exchange topology, two-pion-one-pion exchange topology and ring topology, we evaluate for these all self-closings and concatenations of nucleon-lines to an in-medium loop. The momentum and $k_f$-dependent potentials associated with the isospin operators ($1$ and $\vec\tau_1\!\cdot\!\vec\tau_2$) and five independent spin-structures are expressed in terms of functions, which are either given in closed analytical form or require at most one numerical integration. In the same way we treat the $2\pi$-exchange 3N-force up to fourth order. Our results for $V_\text{med}$ are most helpful to implement the long-range subleading chiral 3N-forces into nuclear many-body calculations.

Over the last decade, frequency comb spectroscopy have led to significant developments in view of the identification of varied species and of the understanding of the structure of matter. Highly efficient amplification of frequency comb femtosecond oscillators in the high pulse energies regime should allow future applications using this approach to Lidar-type measurements. We report on the millijoule level design of femtosecond amplifiers near 2 μm wavelength having a great optical efficiency and compactness in order to be carrier in satellites. In addition to space applications, laser systems at 2 μm become more and more popular because they offer elegant solutions to generate ultra-broad band super-continuum in the mid-infrared and for material processing. Our study helps to compare the optical performance of Tm:YAG, Tm:YAP and Tm:YLF crystals as active media, for designing ultrashort pulse regenerative amplifiers with a high gain and wall-plug efficiencies up to 10%. We will present our approach to ensure the conservation of the initial phase shift between the envelope and the carrier of pulses during amplification. We primarily discuss an innovative model which proposes a gradual path towards the optimization of any regenerative amplifier using crystalline thulium-based, end-pumped doped rods. This also involves the analysis of sizing criteria based on the assumption of rod-based active media, including the doping content, the length of the rod and the beam size inside.

High-density ruthenium (Ru) thin films were deposited using Ru(EtCp)2 (bis(ethylcyclopentadienyl)ruthenium) and oxygen by thermal atomic layer deposition (ALD) and compared to magnetron sputtered (MS) Ru coatings. The ALD Ru film growth and surface roughness show a significant temperature dependence. At temperatures below 200 °C, no deposition was observed on silicon and fused silica substrates. With increasing deposition temperature, the nucleation of Ru starts and leads eventually to fully closed, polycrystalline coatings. The formation of blisters starts at temperatures above 275 °C because of poor adhesion properties, which results in a high surface roughness. The optimum deposition temperature is 250 °C in our tool and leads to rather smooth film surfaces, with roughness values of approximately 3 nm. The ALD Ru thin films have similar morphology compared with MS coatings, e.g., hexagonal polycrystalline structure and high density. Discrepancies of the optical properties can be explained by the higher roughness of ALD films compared to MS coatings. To use ALD Ru for optical applications at short wavelengths (λ = 2–50 nm), further improvement of their film quality is required.

Time durability and environmental stability of silver-coated glass mirrors improve if silver layer is protected by a transparent thin film coating. The choice of the protecting layer material and of the methods for mirror manufacturing influences the mirror optical and mechanical properties. This work reports on a systematic study of silver mirrors overcoated by silicon oxide, nitride and oxy-nitrides. Variable angle spectroscopic ellipsometry was implemented to get an insight on metal-dielectric interface of the coatings. The results have been analyzed considering the coating deposition conditions and physical-chemical properties of the dielectric materials used as protective layers.

An optical system is unimaginable without optical coatings. In optical systems, the shape of the surfaces is designed so that the location and direction of the deflection of the light or the beam are being optimized. Apart from these purely geometrical aspects, however, there are the equally important physical properties, which are essentially determined by the coating. The immense increase in optical applications is continually creating new demands on the performance of the optical coating. In addition to complicated optical performance parameters, the coating also needs to demonstrate other properties, such as radiation stability and environmental resistance. Although there are advanced techniques available for layer design and layer fabrication, skill, experience and a basic understanding are still a prerequisite for the production of efficient coatings. Coating technologies belong to the basic technologies in optics that directly determine the function and performance of optical systems. Optical coatings are typically multilayer systems used to adjust the desired transmission, reflection and absorption of surfaces. Their function is based on the intrinsic properties of the materials (e.g. metal reflectors) and/or on interference effects. Optical coatings offer the opportunity to develop the properties of surfaces to meet the diverse needs of a wide range of applications in modern and future optical technologies. Coating technologies are atomically exact additive nanotechnologies per se. Subtractive nanotechnologies for the atomically exact functionalization of surfaces, e.g. plasma and ion etching, have the same fundamental importance for optics as the coating technologies. Especially the combination of both methods is important. The term functionalization of optical surfaces combines additive and subtractive methods. Furthermore, lithographically structured metal-dielectric optical surfaces, often summarized under the term metamaterials, belong to the surface functionalizations. In addition to the direct adjustment of the spectral transfer function, surface functionalizations are used to optimize a variety of other surface properties, including, for example, environmental stability, abrasion resistance or self-cleaning effects. The new generation of optical surface functionalizations will go even further and combine optical properties with other sophisticated features, such as sensory functionality or active control of selected transmission parameters. This is where the term smart optical surfaces comes in. Surface functionalizations can already be found in every technical device, from eyeglass lenses to mass products, such as smart watches, smart phones, tablet computers, touch screens and laptops, up to high-end products with complex optical systems for basic research, information and laser technology and quantum technologies. In many high-technology sectors, the quality of the available surface functionalizations defines the technical limitations of optical systems and the efficiency of related applications. A prime example are the wafer steppers, undoubtedly the most important machines in the world, as all integrated circuits (ICs) are being produced by them. Therefore, surface functionalizations are one of the key enabling technologies that will drive further progress in many future developments and applications. The most important pacemakers are information technology, semiconductor lithography, medicine, new laser applications, and life sciences. They are pushing the boundaries of thin-film optical technology far beyond the current capabilities of established deposition processes and production strategies. The present collection of papers is a small selection from what is a continuously expanding and developing subject. The editors hope that they will convey the excitement, interest, enthusiasm and drive of the optical coating community that is constantly innovating and responding to new, often formidable, challenges. *Corresponding authors: Norbert Kaiser, Fraunhofer IOF, Optical Coatings, Albert Einstein Str. 7, Jena 07745, Germany; and Zhanshan Wang, School of Physics Science and Engineering, Tongji University, Tongji, China, e-mail: Norbert. Kaiser@iof.fraunhofer.de (N. Kaiser) , wangzs@tongji.edu.cn (Z. Wang)

The behavior of the collective rotor in wobbling motion is investigated within the particle-rotor model for the nucleus $^{135}$Pr by transforming the wave functions from the $K$-representation to the $R$-representation. After reproducing the experimental energy spectra and wobbling frequencies, the evolution of the wobbling mode in $^{135}$Pr, from transverse at low spins to longitudinal at high spins, is illustrated by the distributions of the total angular momentum in the intrinsic reference frame (azimuthal plot). Finally, the coupling schemes of the angular momenta of the rotor and the high-$j$ particle for transverse and longitudinal wobbling are obtained from the analysis of the probability distributions of the rotor angular momentum ($R$-plots) and their projections onto the three principal axes ($K_R$-plots).

Brueckner theory is used to investigate the in-medium properties of a \(\Lambda\)-hyperon in nuclear and neutron matter, based on hyperon-nucleon interactions derived within SU(3) chiral effective field theory (EFT). It is shown that the resulting \( \Lambda\) single-particle potential \(U_{\Lambda}(p_{\Lambda} = 0,\rho)\) becomes strongly repulsive for densities \(\rho\) of two-to-three times that of normal nuclear matter. Adding a density-dependent effective \(\Lambda N\)-interaction constructed from chiral \(\Lambda NN\) three-body forces increases the repulsion further. Consequences of these findings for neutron stars are discussed. It is argued that for hyperon-nuclear interactions with properties such as those deduced from the SU(3) EFT potentials, the onset for hyperon formation in the core of neutron stars could be shifted to much higher density which, in turn, could pave the way for resolving the so-called hyperon puzzle.

A density-dependent effective potential for the baryon-baryon interaction in the presence of the (hyper)nuclear medium is constructed, based on the leading (irreducible) three-baryon forces derived within SU(3) chiral effective field theory. We evaluate the contributions from three classes: contact terms, one-pion exchange and two-pion exchange. In the strangeness-zero sector we recover the known result for the in-medium nucleon-nucleon interaction. Explicit expressions for the Lambda-nucleon in-medium potential in (asymmetric) nuclear matter are presented. Our results are suitable for implementation into calculations of (hyper)nuclear matter. In order to estimate the low-energy constants of the leading three-baryon forces we introduce the decuplet baryons as explicit degrees of freedom and construct the relevant terms in the minimal non-relativistic Lagrangian. With these, the constants are estimated through decuplet saturation. Utilizing this approximation we provide numerical results for the effect of the three-body force in symmetric nuclear matter and pure neutron matter on the Lambda-nucleon interaction. A moderate repulsion that increases with density is found in comparison to the free Lambda-nucleon interaction.

The evolution of microstructure and reflective properties in a La/B4C and LaN/B4C multilayer was studied at elevated temperatures up to 800°C. It was shown, that the observed opposite period thickness changes in La/B4C and LaN/B4C multilayers during annealing are based on structural modifications and chemical reactions at the interfaces. For T>400°C the period thickness of the La/B4C multilayer decreased, while it increased drastically in the LaN/B4C multilayer, which is explained by the formation of LaB6 crystallites and amorphous BN compounds, respectively. These thermally induced processes also lead to reflectivity drops at the wavelength of ~6.7nm for both investigated systems. Even after annealing at 800°C for 10h the LaN/B4C multilayer showed an EUV reflectance of 12.6%, with is significantly higher than the La/B4C multilayer (2.3%), pointing up their higher thermal resistance.

Random effects in the repeatability of refractive index and absorption edge position of tantalum pentoxide layers prepared by plasma-ion-assisted electron-beam evaporation, ion beam sputtering, and magnetron sputtering are investigated and quantified. Standard deviations in refractive index between 4*10-4 and 4*10-3 have been obtained. Here, lowest standard deviations in refractive index close to our detection threshold could be achieved by both ion beam sputtering and plasma-ion-assisted deposition. In relation to the corresponding mean values, the standard deviations in band-edge position and refractive index are of similar order.

High-reflective coatings are indispensable in order to manufacture mirrors with highest possible reflectivity. The maximum reflectivity can be achieved by all-dielectric coatings; however, the spectral bandwidth of these mirrors is limited. For astronomical applications metal based coatings (Al, Au, Ag) are commonly applied, as they allow high reflectivity and at the same time a broad spectral bandwidth.

The results of a comparative study of Ru-, Mo-, Nb- and Pd- coatings designed for grazing angle applications in the soft X-ray and extreme ultraviolet (EUV) spectrum are presented. Optical properties and temporal stability of coatings were investigated using EUV reflectometry at 13.5nm and grazing incidence X-ray reflectometry (GIXR) with Cu-Kα radiation. Nb- and Mo-coatings showed a strong inclination to surface oxidation at ambient atmosphere leading to reflectivity losses. The Pd coating as a noble transition metal showed the highest oxidation resistance over a period of one year. The best reflective properties at 13.5nm were achieved by Ru coatings. GIXR simulation results of the time dependent surface oxidation were used to predict the reflective properties of the studied coatings following four months of storage in an ambient atmosphere for a wide spectral range (5.0nm–40.0nm).

A formalism for treating the scattering of decuplet baryons in chiral effective field theory is developed. The minimal Lagrangian and potentials in leading-order SU(3) chiral effective field theory for the interactions of octet baryons ($B$) and decuplet baryons ($D$) for the transitions $BB\to BB$, $BB\leftrightarrow DB$, $DB\to DB$, $BB\leftrightarrow DD$, $DB\leftrightarrow DD$, and $DD\to DD$ are provided. As an application of the formalism we compare with results from lattice QCD simulations for $\Omega\Omega$ and $N\Omega$ scattering. Implications of our results pertinent to the quest for dibaryons are discussed.

Random effects in the reproducibility of refractive index and absorption edge position of Ta2O5 layers prepared by plasma-ion assisted electron beam evaporation, ion beam sputtering and magnetron sputtering are investigated and quantified.