Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR

Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials (mu_B > 500 MeV), effects of chiral symmetry, and the equation-of-state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2022, in the context of the worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal

Interactive visualization of CFD data with ISVAS

ISVAS (interactive System for visual data Analysis) is an end-user visualization syste for finite-element analysis and for volume data. The system supports methods that allow an interactive analysis of very large data sets as they are commen in computational fluid dynamics (CFD). The paper presents visualization strategies as well as their realization in ISVAS. The concepts of interaction for configuration and control are outlined. Beside this user-interaction for configuration and control are outlined. Beside this user-interaction with application data by means of specification of the view point, positioning of slices, data probing, and intuitive positioning of seed points for particle tracing are some of the main characteristics of ISVAS

On diarrhoea in adolescents and school toilets: Insights from an Indian village school study

The economics literature on the determinants of diarrhoea focuses on infants; but what about school going adolescents? Our survey in an Indian village school affirms that sanitation, defecation practices at home and school, and the degree of crowding of living space at home are all significant determinants of diarrhoeal incidence for adolescents. Usage of toilets at school varies as a function of gender and existence of a toilet in student's home. Access to toilets is not sufficient to guarantee their usage. To eliminate open defecation: toilets installation, behavioural change, and sustainable mechanisms to maintain school toilets seem necessary

The current limits of the laser-acoustic test method to characterize low-k films

The intention to make isolator films with dielectric constants <2.2 has initiated the development of porous siloxane-based films like silica xerogel and silsesquioxane-type materials. Although, the dielectric properties achieved are promising, introducing the technology still requires adapting their mechanical stability to the subsequent chemo-mechanical polishing (CMP). Porosity up to 50% causes the mechanical resistance to reduce drastically. According to several investigations, a value of more than 2 GPa seems to be required for the elastic modulus quantifying the stiffness of the film material. Efforts are currently undertaken to make high porous low-k films with an elastic modulus as high as possible. This requires the elastic modulus of thin soft films to be measured reliably. Surface acoustic waves have been shown to be very sensitive to thin surface films down to thickness of few nano-meters. This technique has been used to study the properties of low-k silica xerogel SiCOH-films. Until now it is necessary to prepare thicker films about 1000 nm for any elastic measurement in order to ensure, that elastic measurement is reliable. The goal of the investigation was to evaluate the extensibility of laser-acoustic based elasticity analysis to films with thickness below 500 nm