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4 results on '"Humphries O"'

1. Toward using collective x-ray Thomson scattering to study C-H demixing and hydrogen metallization in warm dense matter conditions

Author

Ranjan, D, Ramakrishna, K, Voigt, K, Humphries, O, Heuser, B, Stevenson, M, Lütgert, J, He, Z, Qu, C, Schumacher, S, May, P, Amouretti, A, Appel, K, Brambrink, E, Cerantola, V, Chekrygina, D, Fletcher, L, Göde, S, Harmand, M, Hartley, N, Hau-Riege, S, Makita, M, Pelka, A, Schuster, A, Šmíd, M, Toncian, T, Zhang, M, Preston, T, Zastrau, U, Vorberger, J, Kraus, D, Ranjan D., Ramakrishna K., Voigt K., Humphries O. S., Heuser B., Stevenson M. G., Lütgert J., He Z., Qu C., Schumacher S., May P. T., Amouretti A., Appel K., Brambrink E., Cerantola V., Chekrygina D., Fletcher L. B., Göde S., Harmand M., Hartley N. J., Hau-Riege S. P., Makita M., Pelka A., Schuster A. K., Šmíd M., Toncian T., Zhang M., Preston T. R., Zastrau U., Vorberger J., Kraus D., Ranjan, D, Ramakrishna, K, Voigt, K, Humphries, O, Heuser, B, Stevenson, M, Lütgert, J, He, Z, Qu, C, Schumacher, S, May, P, Amouretti, A, Appel, K, Brambrink, E, Cerantola, V, Chekrygina, D, Fletcher, L, Göde, S, Harmand, M, Hartley, N, Hau-Riege, S, Makita, M, Pelka, A, Schuster, A, Šmíd, M, Toncian, T, Zhang, M, Preston, T, Zastrau, U, Vorberger, J, Kraus, D, Ranjan D., Ramakrishna K., Voigt K., Humphries O. S., Heuser B., Stevenson M. G., Lütgert J., He Z., Qu C., Schumacher S., May P. T., Amouretti A., Appel K., Brambrink E., Cerantola V., Chekrygina D., Fletcher L. B., Göde S., Harmand M., Hartley N. J., Hau-Riege S. P., Makita M., Pelka A., Schuster A. K., Šmíd M., Toncian T., Zhang M., Preston T. R., Zastrau U., Vorberger J., and Kraus D.

Abstract

The insulator-metal transition in liquid hydrogen is an important phenomenon to understand the interiors of gas giants, such as Jupiter and Saturn, as well as the physical and chemical behavior of materials at high pressures and temperatures. Here, the path toward an experimental approach is detailed based on spectrally resolved x-ray scattering, tailored to observe and characterize hydrogen metallization in dynamically compressed hydrocarbons in the regime of carbon-hydrogen phase separation. With the help of time-dependent density functional theory calculations and scattering spectra from undriven carbon samples collected at the European x-ray Free-Electron Laser Facility (EuXFEL), we demonstrate sufficient data quality for observing C-H demixing and investigating the presence of liquid metallic hydrogen in future experiments using the reprated drive laser systems at EuXFEL.

Published
2023

2. Imaging x-ray spectrometer at the high energy density instrument of the European x-ray free electron laser

Author

Pan, X, Smid, M, Stefanikova, R, Donat, F, Baehtz, C, Burian, T, Cerantola, V, Gaus, L, Humphries, O, Hajkova, V, Juha, L, Krupka, M, Kozlova, M, Konopkova, Z, Preston, T, Wollenweber, L, Zastrau, U, Falk, K, Pan X., Smid M., Stefanikova R., Donat F., Baehtz C., Burian T., Cerantola V., Gaus L., Humphries O. S., Hajkova V., Juha L., Krupka M., Kozlova M., Konopkova Z., Preston T. R., Wollenweber L., Zastrau U., Falk K., Pan, X, Smid, M, Stefanikova, R, Donat, F, Baehtz, C, Burian, T, Cerantola, V, Gaus, L, Humphries, O, Hajkova, V, Juha, L, Krupka, M, Kozlova, M, Konopkova, Z, Preston, T, Wollenweber, L, Zastrau, U, Falk, K, Pan X., Smid M., Stefanikova R., Donat F., Baehtz C., Burian T., Cerantola V., Gaus L., Humphries O. S., Hajkova V., Juha L., Krupka M., Kozlova M., Konopkova Z., Preston T. R., Wollenweber L., Zastrau U., and Falk K.

Abstract

A multipurpose imaging x-ray crystal spectrometer is developed for the high energy density instrument of the European X-ray Free Electron Laser. The spectrometer is designed to measure x rays in the energy range of 4-10 keV, providing high-resolution, spatially resolved spectral measurements. A toroidally bent germanium (Ge) crystal is used, allowing x-ray diffraction from the crystal to image along a one-dimensional spatial profile while spectrally resolving along the other. A detailed geometrical analysis is performed to determine the curvature of the crystal. The theoretical performance of the spectrometer in various configurations is calculated by ray-tracing simulations. The key properties of the spectrometer, including the spectral and spatial resolution, are demonstrated experimentally on different platforms. Experimental results prove that this Ge spectrometer is a powerful tool for spatially resolved measurements of x-ray emission, scattering, or absorption spectra in high energy density physics.

Published
2023

3. Demonstration of an x-ray Raman spectroscopy setup to study warm dense carbon at the high energy density instrument of European XFEL

Author

Voigt, K, Zhang, M, Ramakrishna, K, Amouretti, A, Appel, K, Brambrink, E, Cerantola, V, Chekrygina, D, Döppner, T, Falcone, R, Falk, K, Fletcher, L, Gericke, D, G??de, S, Harmand, M, Hartley, N, Hau-Riege, S, Huang, L, Humphries, O, Lokamani, M, Makita, M, Pelka, A, Prescher, C, Schuster, A, Šmíd, M, Toncian, T, Vorberger, J, Zastrau, U, Preston, T, Kraus, D, K. Voigt, M. Zhang, K. Ramakrishna, A. Amouretti, K. Appel, E. Brambrink, V. Cerantola, D. Chekrygina, T. Döppner, R. W. Falcone, K. Falk, L. B. Fletcher, D. O. Gericke, S. G??de, M. Harmand, N. J. Hartley, S. P. Hau-Riege, L. G. Huang, O. S. Humphries, M. Lokamani, M. Makita, A. Pelka, C. Prescher, A. K. Schuster, M. Šmíd, T. Toncian, J. Vorberger, U. Zastrau, T. R. Preston, D. Kraus, Voigt, K, Zhang, M, Ramakrishna, K, Amouretti, A, Appel, K, Brambrink, E, Cerantola, V, Chekrygina, D, Döppner, T, Falcone, R, Falk, K, Fletcher, L, Gericke, D, G??de, S, Harmand, M, Hartley, N, Hau-Riege, S, Huang, L, Humphries, O, Lokamani, M, Makita, M, Pelka, A, Prescher, C, Schuster, A, Šmíd, M, Toncian, T, Vorberger, J, Zastrau, U, Preston, T, Kraus, D, K. Voigt, M. Zhang, K. Ramakrishna, A. Amouretti, K. Appel, E. Brambrink, V. Cerantola, D. Chekrygina, T. Döppner, R. W. Falcone, K. Falk, L. B. Fletcher, D. O. Gericke, S. G??de, M. Harmand, N. J. Hartley, S. P. Hau-Riege, L. G. Huang, O. S. Humphries, M. Lokamani, M. Makita, A. Pelka, C. Prescher, A. K. Schuster, M. Šmíd, T. Toncian, J. Vorberger, U. Zastrau, T. R. Preston, and D. Kraus

Abstract

We present a proof-of-principle study demonstrating x-ray Raman Spectroscopy (XRS) from carbon samples at ambient conditions in conjunction with other common diagnostics to study warm dense matter, performed at the high energy density scientific instrument of the European x-ray Free Electron Laser (European XFEL). We obtain sufficient spectral resolution to identify the local structure and chemical bonding of diamond and graphite samples, using highly annealed pyrolytic graphite spectrometers. Due to the high crystal reflectivity and XFEL brightness, we obtain signal strengths that will enable accurate XRS measurements in upcoming pump-probe experiments with a high repetition-rate, where the samples will be pumped with high-power lasers. Molecular dynamics simulations based on density functional theory together with XRS simulations demonstrate the potential of this technique and show predictions for high-energy-density conditions. Our setup allows simultaneous implementation of several different diagnostic methods to reduce ambiguities in the analysis of the experimental results, which, for warm dense matter, often relies on simplifying model assumptions. The promising capabilities demonstrated here provide unprecedented insights into chemical and structural dynamics in warm dense matter states of light elements, including conditions similar to the interiors of planets, low-mass stars, and other celestial bodies.

Published
2021

4. High-resolution inelastic x-ray scattering at the high energy density scientific instrument at the European X-Ray Free-Electron Laser

Author

Wollenweber, L, Preston, T, Descamps, A, Cerantola, V, Comley, A, Eggert, J, Fletcher, L, Geloni, G, Gericke, D, Glenzer, S, G??de, S, Hastings, J, Humphries, O, Jenei, A, Karnbach, O, Konopkova, Z, Loetzsch, R, Marx-Glowna, B, Mcbride, E, Mcgonegle, D, Monaco, G, Ofori-Okai, B, Palmer, C, Pl??ckthun, C, Redmer, R, Strohm, C, Thorpe, I, Tschentscher, T, Uschmann, I, Wark, J, White, T, Appel, K, Gregori, G, Zastrau, U, L. Wollenweber, T. R. Preston, A. Descamps, V. Cerantola, A. Comley, J. H. Eggert, L. B. Fletcher, G. Geloni, D. O. Gericke, S. H. Glenzer, S. G??de, J. Hastings, O. S. Humphries, A. Jenei, O. Karnbach, Z. Konopkova, R. Loetzsch, B. Marx-Glowna, E. E. McBride, D. McGonegle, G. Monaco, B. K. Ofori-Okai, C. A. J. Palmer, C. Pl??ckthun, R. Redmer, C. Strohm, I. Thorpe, T. Tschentscher, I. Uschmann, J. S. Wark, T. G. White, K. Appel, G. Gregori, U. Zastrau, Wollenweber, L, Preston, T, Descamps, A, Cerantola, V, Comley, A, Eggert, J, Fletcher, L, Geloni, G, Gericke, D, Glenzer, S, G??de, S, Hastings, J, Humphries, O, Jenei, A, Karnbach, O, Konopkova, Z, Loetzsch, R, Marx-Glowna, B, Mcbride, E, Mcgonegle, D, Monaco, G, Ofori-Okai, B, Palmer, C, Pl??ckthun, C, Redmer, R, Strohm, C, Thorpe, I, Tschentscher, T, Uschmann, I, Wark, J, White, T, Appel, K, Gregori, G, Zastrau, U, L. Wollenweber, T. R. Preston, A. Descamps, V. Cerantola, A. Comley, J. H. Eggert, L. B. Fletcher, G. Geloni, D. O. Gericke, S. H. Glenzer, S. G??de, J. Hastings, O. S. Humphries, A. Jenei, O. Karnbach, Z. Konopkova, R. Loetzsch, B. Marx-Glowna, E. E. McBride, D. McGonegle, G. Monaco, B. K. Ofori-Okai, C. A. J. Palmer, C. Pl??ckthun, R. Redmer, C. Strohm, I. Thorpe, T. Tschentscher, I. Uschmann, J. S. Wark, T. G. White, K. Appel, G. Gregori, and U. Zastrau

Abstract

We introduce a setup to measure high-resolution inelastic x-ray scattering at the High Energy Density scientific instrument at the European X-Ray Free-Electron Laser (XFEL). The setup uses the Si (533) reflection in a channel-cut monochromator and three spherical diced analyzer crystals in near-backscattering geometry to reach a high spectral resolution. An energy resolution of 44 meV is demonstrated for the experimental setup, close to the theoretically achievable minimum resolution. The analyzer crystals and detector are mounted on a curved-rail system, allowing quick and reliable changes in scattering angle without breaking vacuum. The entire setup is designed for operation at 10 Hz, the same repetition rate as the high-power lasers available at the instrument and the fundamental repetition rate of the European XFEL. Among other measurements, it is envisioned that this setup will allow studies of the dynamics of highly transient laser generated states of matter.

Published
2021

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