We report on experiments aimed at the generation and characterization of solid density plasmas at the free-electron laser FLASH in Hamburg. Aluminum samples were irradiated with XUV pulses at 13.5 nm wavelength (92 eV photon energy). The pulses with duration of a few tens of femtoseconds and pulse energy up to 100 µJ are focused to intensities ranging between 1013 and 1017 W/cm2. We investigate the absorption and temporal evolution of the sample under irradiation by use of XUV and optical spectroscopy. We discuss the origin of saturable absorption, radiative decay, bremsstrahlung and atomic and ionic line emission. Our experimental results are in good agreement with simulations.

We reconstructed climate change during the second half of the Holocene for the Minusinsk (southern Siberia) and the Uyuk (Central Asia) valleys in the Eurasian steppe zone. Sediment cores from 2 lakes and a soil profile from the Arzhan-2 burial mount were investigated. We combined pollen and geochemical analyses and radiocarbon dating with the archaeological record. A sharp increase of human population density occurred at the transition from the Bronze Age to Iron Age (about 2700 cal BP). The most representative Scythian culture started in the Uyuk and the Minusinsk valleys after increased humidity and occupation capacity of the steppe zone during the 9th century BC.

The first radiocarbon dates from the unique early Scythian monument Arzhan-2, discovered in 2001, are presented. The monument contained a royal burial (grave nr 5). Unfortunately, precise dating is hampered by the Hallstatt plateau in the calibration curve. However, using both accelerator mass spectrometry measurements from buried materials and conventional dates for floating tree rings from the burial chamber, we were able to date the construction of the monument to the 7th century BC. This is consistent with archaeological expectations. Other graves located inside the barrow were also dated. Grave nr 11, located on the edge of the barrow, is younger, showing that the monument was a place of burial ritual for many years for this ancient population.

Powder neutron diffraction and magnetization measurements are presented on the Co2Ru1-xMnxO4 system. In these materials the tetrahedral (A) sites are occupied by Co2+ (S = 3/2) ions, and the octahedral (B) sites are jointly occupied by Co3+ (low spin, S = 0), Ru3+ (low spin, S = 1/2), and Mn3+ (S = 2) ions. The measurements reveal that Co2RuO4 undergoes a spin-glass transition, Co2MnO4 is a collinear ferrimagnet, and that Co2Ru0.5Mn0.5O4 undergoes an unusual magnetic double transition. Triple-axis measurements indicate that the lower temperature transition in Co2Ru0.5Mn0.5O4 is characterized by the onset of diffuse scattering and the emergence of short-range order. The Co2Ru1-xMnxO4 series appears to be well-suited for studying the coexistence of long- and short-range magnetic order.