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Der Umgang mit der Natur ist dreißig Jahre nach Hans Jonas‘ „Prinzip Verantwortung“ weiterhin Anlass ethischer Reflexion. Das gesellschaftlich dominante Nutzendenken bringt den Naturschutz trotz der ökologischen Krise in Bedrängnis. Anthropozentrisches Nutzendenken hat den Naturschutz und seine Begründung längst selbst erreicht. Der Mensch kann jedoch weiterhin als Teil der Natur begriffen werden. Dies führt zur ethisch relevanten Frage nach Eigenwerten der Natur, die der Anthropozentrismus negiert. Die einseitige Betonung von Daten und Fakten vernachlässigt die durch eine Primärintuition gestützte, wesentliche Innenseite der Naturschutzargumentation. Diese Gefühlsseite verlangt ethische Rechtfertigung. Am Beispiel des Nutzenansatzes im Naturschutz und dessen Widersprüchlichkeiten wird die Notwendigkeit einer moralischen Grundentscheidung zwischen Nutzenorientierung und Uneigennützigkeit gezeigt. Dabei wird die Plausibilität der anthropozentrisch verengten Sicht einer „Natur ohne eigenen Wert“ in Frage gestellt. Menschliche Freiheit führt zur Verantwortung. Verantwortungsargumente sprechen für eine Ethik, die Eigenwerte nicht nur für den Menschen, sondern für die Natur annimmt und berücksichtigt. Unter Bezug auf die vor dreißig Jahren formulierte Verantwortungsethik wird die Ausdehnung der Moralgemeinschaft in aktuellen nicht-anthropozentrischen Ethikkonzepten beleuchtet. Die Entwicklung der Moralfähigkeit des Menschen, seine einzigartige Fähigkeit zum Abbau von Egozentrik bis hin zur barmherzigen Weltsicht, zum Altruismus über die Artgrenze hinweg, speist die Hoffnung auf einen umfassenden Kulturwandel zur Beendigung des Raubbaus an der Natur. Dieser Kulturwandel könnte durch Überwindung des Anthropozentrismus ethisch angemessen begleitet werden. Die Sonderstellung des Menschen ermöglicht diese Sprengung des anthropozentrischen Denkrahmens. Konkrete Folgen des ganzheitlich ethischen Arguments für Eigenwerte der Natur, besonders die Beweislastumkehr für den Naturschutz werden beleuchtet.
Partial wave analysis of the reaction p(3.5 GeV) + p → pK +Λ to search for the "ppK−" bound state
(2015)
Employing the Bonn–Gatchina partial wave analysis framework (PWA), we have analyzed HADES data of the reaction p(3.5 GeV) + p → pK +Λ. This reaction might contain information about the kaonic cluster “ppK −” (with quantum numbers J P = 0− and total isospin I = 1/2) via its decay into pΛ. Due to interference effects in our coherent description of the data, a hypothetical KNN (or, specifically “ppK −”) cluster signal need not necessarily show up as a pronounced feature (e.g. a peak) in an invariant mass spectrum like pΛ. Our PWA analysis includes a variety of resonant and non-resonant intermediate states and delivers a good description of our data (various angular distributions and two-hadron invariant mass spectra) without a contribution of a KNN cluster. At a confidence level of CLs = 95% such a cluster cannot contribute more than 2–12% to the total cross section with a pK +Λ final state, which translates into a production cross-section between 0.7 μb and 4.2 μb, respectively. The range of the upper limit depends on the assumed cluster mass, width and production process.
Many QCD based and phenomenological models predict changes of hadron properties in a strongly interacting environment. The results of these models differ significantly and the experimental determination of hadron properties in nuclear matter is essential. In this paper we present a review of selected physics results obtained at GSI Helmholtzzentrum für Schwerionenforschung GmbH by HADES (High-Acceptance Di-Electron Spectrometer). The e+e− pair emission measured for proton and heavy-ion induced collisions is reported together with results on strangeness production. The future HADES activities at the planned FAIR facility are also discussed.
The knowledge of baryonic resonance properties and production cross sections plays an important role for the extraction and understanding of medium modifications of mesons in hot and/or dense nuclear matter. We present and discuss systematics on dielectron and strangeness production obtained with HADES on p+p, p+A and A+A collisions in the few GeV energy regime with respect to these resonances.
The High Acceptance DiElectron Spectrometer HADES [1] is installed at the Helmholtzzentrum für Schwerionenforschung (GSI) accelerator facility in Darmstadt. It investigates dielectron emission and strangeness production in the 1-3 AGeV regime. A recent experiment series focusses on medium-modifications of light vector mesons in cold nuclear matter. In two runs, p+p and p+Nb reactions were investigated at 3.5 GeV beam energy; about 9·109 events have been registered. In contrast to other experiments the high acceptance of the HADES allows for a detailed analysis of electron pairs with low momenta relative to nuclear matter, where modifications of the spectral functions of vector mesons are predicted to be most prominent. Comparing these low momentum electron pairs to the reference measurement in the elementary p+p reaction, we find in fact a strong modification of the spectral distribution in the whole vector meson region.
Electromagnetic calorimeter (ECAL) is being developed to complement dilepton spectrometer HADES. ECAL will enable the HADES@FAIR experiment to measure data on neutral meson production in heavy ion collisions at the energy range of 2-10 AGeV on the beam of future accelerator SIS100@FAIR. We will report results of the last beam test with quasi-monoenergetic photons carried out in MAMI facility at Johannes Gutenberg Universität Mainz.
We present first data on sub-threshold production of Ks0 mesons and Λ hyperons in Au+Au collisions at sNN=2.4 GeV. We observe an universal 〈Apart〉 scaling of hadrons containing strangeness, independent of their corresponding production thresholds. Comparing the yields, their 〈Apart〉 scaling, and the shapes of the rapidity and the pt spectra to state-of-the-art transport model (UrQMD, HSD, IQMD) predictions, we find that none of them can simultaneously describe these observables with reasonable χ2 values.
In this letter we report the first multi-differential measurement of correlated pion-proton pairs from 2 billion Au+Au collisions at sNN=2.42 GeV collected with HADES. In this energy regime the population of Δ(1232) resonances plays an important role in the way energy is distributed between intrinsic excitation energy and kinetic energy of the hadrons in the fireball. The triple differential d3N/dMπ±pdpTdy distributions of correlated π±p pairs have been determined by subtracting the πp combinatorial background using an iterative method. The invariant-mass distributions in the Δ(1232) mass region show strong deviations from a Breit-Wigner function with vacuum width and mass. The yield of correlated pion-proton pairs exhibits a complex isospin, rapidity and transverse-momentum dependence. In the invariant mass range 1.1<Minv(GeV/c2)<1.4, the yield is found to be similar for π+p and π−p pairs, and to follow a power law 〈Apart〉α, where 〈Apart〉 is the mean number of participating nucleons. The exponent α depends strongly on the pair transverse momentum (pT) while its pT-integrated and charge-averaged value is α=1.5±0.08st±0.2sy.
We investigate identical pion HBT intensity interferometry in central Au+Au collisions at 1.23A GeV. High-statistics π−π− and π+π+ data are measured with HADES at SIS18/GSI. The radius parameters, derived from the correlation function depending on relative momenta in the longitudinally comoving system and parametrized as three-dimensional Gaussian distribution, are studied as function of transverse momentum. A substantial charge-sign difference of the source radii is found, particularly pronounced at low transverse momentum. The extracted source parameters agree well with a smooth extrapolation of the center-of-mass energy dependence established at higher energies, extending the corresponding excitation functions down towards a very low energy.