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29 results on '"Dollinger, Guenther"'

2. Physics at the Munich Tandem Accelerator Laboratory

Author

Dollinger, Günther and Faestermann, Thomas

Subjects
Nuclear Experiment
Abstract

This review reports on the science performed in various fields at the Munich tandem accelerator during the past decade. It covers nuclear structure studies, also with respect to astro- and particle physics as well as for the understanding of fundamental symmetries, the extremely sensitive detection of long-lived radionuclides from Supernova or r-process production with accelerator mass spectrometry and studies of the elemental composition of thin films with extreme depth resolution and sensitivity by elastic recoil detection (ERD). The ion microbeam is used for 3D hydrogen microscopy as well as in radiobiology to study the response of living cells on well-defined irradiations. In medical research new therapeutic methods of tumour irradiation are tested using proton minibeams as well as the determination of ion ranges in tissue with iono-acoustics. Primary and secondary beams from the accelerator are also used for development and testing of detector components in large setups, e.g. at the LHC, and for testing new kinds of fuel materials of high uranium density to use them as medium enriched fuels at the Munich research reactor FRM II in the future., Comment: A shortened version of this article appeared in the March 2018 issue of Nuclear Physics News Vol. 28, Issue 1

Published
2018

13. A Carbon Minibeam Irradiation Facility Concept

Author

Mayerhofer, Michael, Bencini, Vittorio, Dollinger, Guenther, and Sammer, Matthias

Subjects
History, Accelerators and Storage Rings, Accelerator Physics, MC8: Applications of Accelerators, Technology Transfer and Industrial Relations, Computer Science Applications, Education
Abstract

In minibeam therapy, the sparing of deep-seated normal tissue is limited by transverse beam spread caused by small-angle scattering. Contrary to proton minibeams, helium or carbon minibeams experience less deflection, which potentially reduces side effects. To verify this potential, an irradiation facility for preclinical and clinical studies is needed. This manuscript presents a concept for a carbon minibeam irradiation facility based on a LINAC design for conventional carbon therapy. A quadrupole triplet focuses the LINAC beam to submillimeter minibeams. A scanning and a dosimetry unit are provided to move the minibeam over the target and monitor the applied dose. The beamline was optimized by TRAVEL simulations. The interaction between beam and these components and the resulting beam parameters at the focal plane is evaluated by TOPAS simulations. A transverse beamwidth of 100 µm (σ) and a peak-to-valley (energy) dose ratio of > 1000 results for carbon energies of 100 MeV/u and 430 MeV/u (about 3 cm and 30 cm range in water) whereby the average beam current is about 30 nA. Therefore, the presented irradiation facility exceeds the requirements for hadron minibeam therapy., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

Published
2022

19. Hydrogen concentration analysis in clinopyroxene using proton-proton scattering analysis

Author

Weis, Franz, Ros, Linus, Reichart, Patrick, Skogby, Henrik, Kristiansson, Per, Dollinger, Guenther, Weis, Franz, Ros, Linus, Reichart, Patrick, Skogby, Henrik, Kristiansson, Per, and Dollinger, Guenther

Abstract

Traditional methods to measure water in nominally anhydrous minerals (NAMs) are, for example, Fourier transformed infrared (FTIR) spectroscopy or secondary ion mass spectrometry (SIMS). Both well-established methods provide a low detection limit as well as high spatial resolution yet may require elaborate sample orientation or destructive sample preparation. Here we analyze the water content in erupted volcanic clinopyroxene phenocrysts by proton-proton scattering and reproduce water contents measured by FTIR spectroscopy. We show that this technique provides significant advantages over other methods as it can provide a three-dimensional distribution of hydrogen within a crystal, making the identification of potential inclusions possible as well as elimination of surface contamination. The sample analysis is also independent of crystal structure and orientation and independent of matrix effects other than sample density. The results are used to validate the accuracy of wavenumber-dependent vs. mineral-specific molar absorption coefficients in FTIR spectroscopy. In addition, we present a new method for the sample preparation of very thin crystals suitable for proton-proton scattering analysis using relatively low accelerator potentials.

Published
2018
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21. Live cell imaging of mitochondria following targeted irradiation in situ reveals rapid and highly localized loss of membrane potential

Author

Walsh, Dietrich W. M., primary, Siebenwirth, Christian, additional, Greubel, Christoph, additional, Ilicic, Katarina, additional, Reindl, Judith, additional, Girst, Stefanie, additional, Muggiolu, Giovanna, additional, Simon, Marina, additional, Barberet, Philippe, additional, Seznec, Hervé, additional, Zischka, Hans, additional, Multhoff, Gabriele, additional, Schmid, Thomas E., additional, and Dollinger, Guenther, additional

Published
2017
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26. Physical characterization of thin ALD–Al2O3 films

Author

Jakschik, Stefan, primary, Schroeder, Uwe, additional, Hecht, Thomas, additional, Krueger, Dietmar, additional, Dollinger, Guenther, additional, Bergmaier, Andreas, additional, Luhmann, Claudia, additional, and Bartha, Johann W, additional

Published
2003
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27. Ionoacoustic tomography of the proton Bragg peak in combination with ultrasound and optoacoustic imaging

Author

Kellnberger, Stephan, Assmann, Walter, Lehrack, Sebastian, Reinhardt, Sabine, Thirolf, Peter, Queirós, Daniel, Sergiadis, George, Dollinger, Günther, Parodi, Katia, and Ntziachristos, Vasilis

Abstract

Ions provide a more advantageous dose distribution than photons for external beam radiotherapy, due to their so-called inverse depth dose deposition and, in particular a characteristic dose maximum at their end-of-range (Bragg peak). The favorable physical interaction properties enable selective treatment of tumors while sparing surrounding healthy tissue, but optimal clinical use requires accurate monitoring of Bragg peak positioning inside tissue. We introduce ionoacoustic tomography based on detection of ion induced ultrasound waves as a technique to provide feedback on the ion beam profile. We demonstrate for 20 MeV protons that ion range imaging is possible with submillimeter accuracy and can be combined with clinical ultrasound and optoacoustic tomography of similar precision. Our results indicate a simple and direct possibility to correlate, in-vivo and in real-time, the conventional ultrasound echo of the tumor region with ionoacoustic tomography. Combined with optoacoustic tomography it offers a well suited pre-clinical imaging system.

Published
2016
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28. Doping Density Depth Profiling Analysis with High Resolution Elastic Recoil Detection

Author

Bergmaier, Andreas and Dollinger, Guenther

Abstract

The quantitative analysis of light elements in ultra thin films thinner than 10 nm is still a nontrivial task. This paper summarizes the prospects of high-resolution Elastic Recoil Detection (ERD) using a Q3D magnetic spectrograph. It is shown that sub-nanometer resolution can be achieved in ultra thin films and even monolayer resolution is possible close to the surface. ERD has the best quantification possibilities compared to any other method. Sensitivity is sufficient to analyze main elements and impurities as e.g. necessary for the characterization of microelectronic materials. In addition, high-resolution channeling ERD can be performed in order to obtain information on lattice location of light elements in crystalline ultra thin layers. The potential of high-resolution ERD is demonstrated by several applications where it is the most valuable tool for elemental profiling.

Published
2007

29. Physical characterization of thin ALD–Al<F>2</F>O<F>3</F> films

Author

Jakschik, Stefan, Schroeder, Uwe, Hecht, Thomas, Krueger, Dietmar, Dollinger, Guenther, Bergmaier, Andreas, Luhmann, Claudia, and Bartha, Johann W.

Subjects
*OZONE, *ALUMINUM compounds
Abstract

Aluminum oxide was deposited using atomic layer deposition on either a silicon oxide or a silicon nitride interface. Water vapor or ozone were used as oxidation precursors. The structural properties of these films were investigated by time-of-flight secondary-ion-mass-spectroscopy (ToF-SIMS), X-ray photoelectron spectroscopy (XPS) and elastic recoil detection (ERD). Special attention was given to contamination issues of the film and the interface, bonding conditions and temperature influence on diffusion. The results suggest that the silicon most likely diffused along grain boundaries of polycrystalline Al2O3. Carbon and hydrogen were located at the interface and furthermore hydrogen diffused out of the film to some extent due to anneal. Carbon content in the layer was reduced when using O3 as an oxidant. The formation of metallic aluminum clusters was not observed for any of the investigated process conditions. [Copyright &y& Elsevier]

Published
2003
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