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In the laboratory study of extreme conditions of temperature and density, the exposure of matter to high intensity radiation sources has been of central importance. Here, we interrogate the performance of multi-layered targets in experiments involving high intensity, hard x-ray irradiation, motivated by the advent of extremely high brightness hard x-ray sources, such as free electron lasers and 4th-generation synchrotron facilities. Intense hard x-ray beams can deliver significant energy in targets having thick x-ray transparent layers (tampers) around samples of interest for the study of novel states of matter and materials' dynamics. Heated-state lifetimes in such targets can approach the microsecond level, regardless of radiation pulse duration, enabling the exploration of conditions of local thermal and thermodynamic equilibrium at extreme temperature in solid density matter. The thermal and mechanical responses of such thick layered targets following x-ray heating, including hydrodynamic relaxation and heat flow on picosecond to millisecond timescales, are modeled using radiation hydrocode simulation, finite element analysis, and thermodynamic calculations. Assessing the potential for target survival over one or more exposures and resistance to damage arising from heating and resulting mechanical stresses, this study doubles as an investigation into the performance of diamond anvil high pressure cells under high x-ray fluences. Long used in conjunction with synchrotron x-ray radiation and high power optical lasers, the strong confinement afforded by such cells suggests novel applications at emerging high intensity x-ray facilities and new routes to studying thermodynamic equilibrium states of warm, very dense matter. [ABSTRACT FROM AUTHOR]

Recent advances in storage ring technology pioneered by MAX IV (Sweden) allow synchrotron radiation sources to achieve significantly smaller emittances than those currently in operation. This new, multi-bend achromat technology can thus boost spectral brightness, enabling unprecedented experimental possibilities. The high-energy synchrotron radiation facilities ESRF (France), SPring-8 (Japan), and APS (USA) have settled upgrade plans to improve their storage ring emittance by up to two orders of magnitude at 6 GeV electron energy. PETRA III at DESY has the largest circumference with 2.3 km. As the emittance scales favorably with the storage ring size, an upgrade of PETRA III offers the unique potential to reach a diffraction limit up to X-ray energies of 10 keV. Operating at 6 GeV with an emittance of 10 pmrad, this PETRA IV facility would pave the way for new experimental opportunities, especially for those using high photon energies. [ABSTRACT FROM AUTHOR]

Using a synchrotron radiation source and a diamond anvil cell, we measured the pressure dependence of the lattice parameters of a polycrystalline Ti3Si0.5Ge0.5C2 sample. Up to a pressure of 53 GPa, no phase transformations were observed. As for the isostructural hexagonal Ti3SiC2, the compressibility along the c axis was greater than along a. The bulk modulus is 183±4 GPa with a pressure derivative of 3.4±0.2. This work shows that the replacement of Si by Ge in Ti3SiC2 results in a systematic decrease in the bulk moduli. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The Sr analogue of the mineral fresnoite (Sr2TiSi2O8) is of interest as a potential storage medium for radioactive Sr from nuclear waste. No high or low temperature crystal structure information is known on this phase. Therefore high-resolution synchrotron X-ray powder diffraction measurements have been done on a synthetic sample of Sr-fresnoite in the temperature range 87-1223K. This was done as a test experiment using the HRPD beamline P02.1 at PETRA-III, DESY. Synchrotron X-ray wavelengths of 0.2067(3)Å (293K and 573-1223K) and 0.2079(3)Å (87-499K) were used. Powder diffraction data were collected with a counting time of 30s using a PerkinElmer XRD 1621 flat panel image plate detector. CeO2 was included as an internal standard to calibrate the sample to detector distance. The P4bm tetragonal crystal structure of fresnoite (Ba2TiSi2O8) was used as a starting model for Sr-fresnoite. Small amounts of SrTiO3 and SrSiO3 were also found as impurities in this sample; therefore four-phase Rietveld refinements were done. The P4bm fresnoite structure is retained over the temperature range 87-1223K. [ABSTRACT FROM PUBLISHER]

Modifications of structural arrangements including relaxation processes were investigated in swift-heavy-ion-bombarded Fe 73 Cu 1 Nb 3 Si 16 B 7 metallic glass. The irradiation of as-quenched amorphous ribbons was accomplished with 3 MeV u −1 (u is atomic mass unit) and 11.1 MeV u −1 Au ions with total fluences of up to 1 × 10 13 ions cm −2 . Specimens irradiated with 3 MeV u −1 ions were subsequently annealed for 4 h at 350 °C. Ion-irradiated samples including those heat-treated were studied using in situ temperature-dependent diffraction of high-energy X-ray synchrotron radiation (wavelength of 0.020689 nm). Cyclic heating–cooling regimes were applied during the measurements. A tendency towards a higher degree of disorder was revealed as a function of the ion fluence in both types of alloys. During the first heating–cooling cycle, a remarkable hysteresis is observed in the position and line width of the first diffraction peak, especially in the as-quenched irradiated alloys. The hysteresis increases with rising ion fluence but vanishes completely after the first heating–cooling cycle. No hysteresis is found in the irradiated and subsequently annealed alloys. The irradiation-induced structural modifications have some features similar to the effects caused by mechanical deformation. [ABSTRACT FROM AUTHOR]