2023 |
|
A carbon minibeam irradiation facility concept M. Mayerhofer, V. Bencini, M. Sammer and G. Dollinger; Journal of Physics: Conference Series 2420 (1) (2023) 012097. |
| 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 (sigma) and a peak-to-valley (energy) dose ratio of > 1000 results for carbon energies of 100 MeV/u and 430 MeV/u (∼ 3 cm and 30 cm range in water) whereby the average beam current is ∼ 30 nA. Therefore, the presented irradiation facility exceeds the requirements for hadron minibeam therapy. |
BibTeX:
@article{Mayerhofer2023,
author = {Mayerhofer, M. and Bencini, V. and Sammer, M. and Dollinger, G.},
title = {A carbon minibeam irradiation facility concept},
journal = {Journal of Physics: Conference Series},
publisher = {IOP Publishing},
type = {OpenAccess},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2023},
volume = {2420},
number = {1},
pages = {012097},
url = {https://iopscience.iop.org/article/10.1088/1742-6596/2420/1/012097},
doi = {https://doi.org/10.1088/1742-6596/2420/1/012097}
}
|
|
Additive Manufacturing of Side-Coupled Cavity Linac Structures from Pure Copper: A First Concept M. Mayerhofer, S. Brenner, R. Helm, S. Gruber, E. Lopez, L. Stepien, G. Gold and G. Dollinger; Instruments 7 (4) (2023) 56. |
| Abstract: Compared to conventional manufacturing, additive manufacturing (AM) of radio frequency (RF) cavities has the potential to reduce manufacturing costs and complexity and to enable higher performance. This work evaluates whether normal conducting side-coupled linac structures (SCCL), used worldwide for a wide range of applications, can benefit from AM. A unit cell geometry (SC) optimized for 75 MeV protons was developed. Downskins with small downskin angles α were avoided to enable manufacturing by laser powder bed fusion without support structures. SCs with different α were printed and post-processed by Hirtisation (R) (an electrochemical process) to minimize surface roughness. The required accuracy for 3 GHz SCCL (medical linacs) is achieved only for α>45∘. After a material removal of 140 µm due to Hirtisation (R), a quality factor Q0 of 6650 was achieved. This corresponds to 75% of the Q0 simulated by CST®. A 3 GHz SCCL concept consisting of 31 SCs was designed. The effective shunt impedance ZT2 simulated by CST corresponds to 60.13MΩm and is comparable to the ZT2 of SCCL in use. The reduction in ZT2 expected after Hirtisation (R) can be justified in practice by up to 70% lower manufacturing costs. However, future studies will be conducted to further increase Q0. |
BibTeX:
@article{Mayerhofer2023a,
author = {Mayerhofer, Michael and Brenner, Stefan and Helm, Ricardo and Gruber, Samira and Lopez, Elena and Stepien, Lukas and Gold, Gerald and Dollinger, Günther},
title = {Additive Manufacturing of Side-Coupled Cavity Linac Structures from Pure Copper: A First Concept},
journal = {Instruments},
type = {OpenAccess},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2023},
volume = {7},
number = {4},
pages = {56},
url = {https://www.mdpi.com/2410-390X/7/4/56},
doi = {https://doi.org/10.3390/instruments7040056}
}
|
|
First high quality DTL cavity additively manufactured from pure copper M. Mayerhofer, J. Mitteneder, C. Wittig, I. Prestes, E. Jägle and G. Dollinge; In: , R. Assmann, P. McIntosh, G. Bisoffi, Elettra-Sincrotrone, I. Andrian and G. Vinicola (Eds.), Proc. 14th International Particle Accelerator Conference (IPAC'23) , JACoW 14 (2023) 4967-4970 , JACoW Publishing, Geneva, Switzerland. |
| Abstract: Recently presented RF cavity prototypes printed entirely from pure copper illustrate the potential of additive manufacturing (AM), and particularly laser powder bed fusion (L-PBF), for accelerator technology. Thereby, the design freedom of L-PBF is only limited by overhanging geometries, which have to be printed with supporting structures to ensure sufficient accuracy. However, subsequent removal of these support structures is a major challenge for cm-sized GHz cavities. Therefore, our approach is to design self-supporting geometries. In this contribution we present a DTL cavity geometry as used in e.g. proton therapy linac systems that can be fabricated by L-PBF without support structures. A 5-cell prototype was manufactured from high-purity copper using L-PBF. It is shown that the developed geometry allows a print accuracy sufficient to reach the defined resonance frequency. A chemical, as well as dynamic electrochemical finishing process, was applied to optimize the prototypes surface quality. Thus, the CST simulated figures of merit (e.g., Q_0, Z_eff) were obtained for the first time with a printed cavity. |
BibTeX:
@inproceedings{Mayerhofer2023b,
author = {Mayerhofer, M. and Mitteneder, J. and Wittig, C. and Prestes, I. and Jägle, E. and Dollinge, G.},
title = {First high quality DTL cavity additively manufactured from pure copper},
booktitle = {Proc. 14th International Particle Accelerator Conference (IPAC'23)},
journal = {JACoW},
publisher = {JACoW Publishing, Geneva, Switzerland},
type = {OpenAccess},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2023},
volume = {14},
number = {13},
pages = {4967-4970},
editor = {Ralph Assmann and Peter McIntosh and Giovanni Bisoffi and Elettra-Sincrotrone and Ivan Andrian and Giulia Vinicola},
url = {https://accelconf.web.cern.ch/ipac2023/doi/jacow-ipac2023-thpm035/},
doi = {https://doi.org/10.18429/JACoW-IPAC2023-THPM035}
}
|
|
Entwicklung eines Störkörpermessstandes zur Charakterisierung von Hochfrequenz-Hohlraumresonatoren Cedric Wittig; Bachelors-Thesis, Universität der Bundeswehr München, 2023. |
| Abstract: Die resonante Störkörpermessung ist eine Methode zur Charakterisierung des elektromagnetischen Feldes in Hochfrequenz-Hohlraumresonatoren (fortlaufend als Resonator bezeichnet) und gilt als schnelles und zuverlässiges Mittel zur Bestimmung wichtiger Kenngrößen, wie z.B. den Gütefaktor QL. Durch Einbringen eines dielektrischen Körpers in einen Resonator verschiebt sich auf Grund der hervorgerufenen Kapazitätserhöhung die Resonanzfrequenz. Anhand der lokalen Bestimmung dieser Frequenzverschiebung an zahlreichen Messpunkten auf der Strahlachse ist es möglich, die Verteilung des elektrischen Feldes und folglich die Shunt-Impedanz als Indikator der Performance eines Resonators zu bestimmen. Im Rahmen dieser Arbeit wird ein Störkörpermessstand entwickelt, mit dem die resonante Störkörpermessung für Resonatoren automatisch und in kurzer Zeit durchgeführt werden kann. Der Messstand besteht im wesentlichen aus einem motorisierten Linearmodul, einem Mikrocontroller und einem Vektor-Netzwerk-Analysator, welche zentral über eine auf LabV IEW basierende Messstand-Software gesteuert werden. Um den Messstand zu charakterisieren, werden verschiedene Messungen der TM010-Mode an einem bereits charakterisierten Driftröhrenlinearbeschleuniger (engl. Drift Tube Linac (DTL)) durchgeführt. Zunächst wird die Störkörperkonstante α bestimmt, welche den Einfluss des Störkörpers auf das elektrische Feld beschreibt. Anschließend erfolgt unter Betrachtung verschiedener Abstände der einzelnen Messpunkte eine Bestimmung der relativen und absoluten Messgenauigkeit der Feldamplituden und deren Position in longitudinaler Richtung am Störkörpermessstand. Abschließend wird ein mittels Additiver Fertigung hergestellter DTL durch den entwickelten Störkörpermessstand charakterisiert und dessen Shunt-Impedanz bestimmt. |
BibTeX:
@mastersthesis{Wittig2023,
author = {Wittig, Cedric},
title = {Entwicklung eines Störkörpermessstandes zur Charakterisierung von Hochfrequenz-Hohlraumresonatoren},
school = {Universität der Bundeswehr München},
year = {2023}
}
|
2022 |
|
A 3D printed pure copper drift tube linac prototype M. Mayerhofer, J. Mitteneder and G. Dollinger; Review of Scientific Instruments 93 (2) (2022) 023304. |
| Abstract: Radio frequency cavities are among the most challenging and costly components of an accelerator facility. They are usually manufactured in individual parts, which are then joined by complex processes, e.g., several brazing steps. 3D printing has become an alternative to these conventional manufacturing methods due to higher cost efficiency, freedom in design, and recent achievement of high print quality for pure copper. A fully functional 3 GHz drift tube linac (DTL) prototype was 3D printed in one piece, made from pure copper by selective laser melting (SLM). To achieve a higher surface quality, the DTL geometry was optimized for the SLM process. The DTL design is related to the design of the DTL part of the side-coupled DTL modules used in linac-based proton therapy facilities. The quality factor (8750) and the shunt impedance per unit length (102 mΩ/m) of the printed prototype are already comparable to traditionally manufactured DTL structures and can be further enhanced by surface treatments. |
BibTeX:
@article{Mayerhofer2022,
author = {Mayerhofer, Michael and Mitteneder, Johannes and Dollinger, Günther},
title = {A 3D printed pure copper drift tube linac prototype},
journal = {Review of Scientific Instruments},
type = {OpenAccess},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2022},
volume = {93},
number = {2},
pages = {023304},
url = {https://aip.scitation.org/doi/full/10.1063/5.0068494},
doi = {https://doi.org/10.1063/5.0068494}
}
|
|
A Carbon Minibeam Irradiation Facility Concept M. Mayerhofer, V. Bencini, G. Dollinger and M.A. Sammer; In: Proc. 13th International Particle Accelerator Conference (IPAC'22) , JACoW (2022) 2947-2950 , JACoW Publishing, Geneva, Switzerland. |
| 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. |
BibTeX:
@inproceedings{Mayerhofer2022a,
author = {Mayerhofer, M. and Bencini, V. and Dollinger, G. and Sammer, M. A.},
title = {A Carbon Minibeam Irradiation Facility Concept},
booktitle = {Proc. 13th International Particle Accelerator Conference (IPAC'22)},
journal = {JACoW},
publisher = {JACoW Publishing, Geneva, Switzerland},
type = {OpenAccess},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2022},
number = {13},
pages = {2947--2950},
url = {https://jacow.org/ipac2022/papers/thpoms006.pdf},
doi = {https://doi.org/10.18429/JACoW-IPAC2022-THPOMS006}
}
|
|
Proton beam range verification by means of ionoacoustic measurements at clinically relevant doses using a correlation-based evaluation J. Schauer, H.-P. Wieser, Y. Huang, H. Ruser, J. Lascaud, M. Würl, A. Chmyrov, M. Vidal, J. Herault, V. Ntziachristos, W. Assmann, K. Parodi and G. Dollinger; Frontiers in Oncology 12:925542 (2022) 1-18. |
| Abstract: |
BibTeX:
@article{Schauer2022a,
author = {Schauer, Jannis and Wieser, Hans-Peter and Huang, Yuanhui and Ruser, Heinrich and Lascaud, Julie and Würl, Matthias and Chmyrov, Andriy and Vidal, Marie and Herault, Joel and Ntziachristos, Vasilis and Assmann, Walter and Parodi, Katia and Dollinger, Günther},
title = {Proton beam range verification by means of ionoacoustic measurements at clinically relevant doses using a correlation-based evaluation},
journal = {Frontiers in Oncology},
type = {OpenAccess},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2022},
volume = {12:925542},
pages = {1--18},
url = {https://www.frontiersin.org/articles/10.3389/fonc.2022.925542},
doi = {https://doi.org/10.3389/fonc.2022.925542}
}
|
2021 |
|
Concept and performance evaluation of two 3 GHz buncher units optimizing the dose rate of a novel preclinical proton minibeam irradiation facility M. Mayerhofer, A. Bergmaier, G. Datzmann, H. Hagn, R. Helm, J. Mitteneder, R. Schubert, L. Picardi, P. Nenzi, C. Ronsivalle, H.-F. Wirth and G. Dollinger; PLOS ONE 16 (10) (2021) 1-19. |
| Abstract: To demonstrate the large potential of proton minibeam radiotherapy (pMBRT) as a new method to treat tumor diseases, a preclinical proton minibeam radiation facility was designed. It is based on a tandem Van-de-Graaff accelerator providing a 16 MeV proton beam and a 3 GHz linac post-accelerator (designs: AVO-ADAM S.A, Geneva, Switzerland and ENEA, Frascati, Italy). To enhance the transmission of the tandem beam through the post-accelerator by a factor of 3, two drift tube buncher units were designed and constructed: A brazed 5-gap structure (adapted SCDTL tank of the TOP-IMPLART project (ENEA)) and a non-brazed low budget 4-gap structure. Both are made of copper. The performance of the two differently manufactured units was evaluated using a 16 MeV tandem accelerator beam and a Q3D magnetic spectrograph. Both buncher units achieve the required summed voltage amplitude of 42 kV and amplitude stability at a power feed of less than 800 W. |
BibTeX:
@article{Mayerhofer2021a,
author = {Mayerhofer, Michael and Bergmaier, Andreas and Datzmann, Gerd and Hagn, Hermann and Helm, Ricardo and Mitteneder, Johannes and Schubert, Ralf and Picardi, Luigi and Nenzi, Paolo and Ronsivalle, Concetta and Wirth, Hans-Friedrich and Dollinger, Günther},
title = {Concept and performance evaluation of two 3 GHz buncher units optimizing the dose rate of a novel preclinical proton minibeam irradiation facility},
journal = {PLOS ONE},
publisher = {Public Library of Science},
type = {OpenAccess},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2021},
volume = {16},
number = {10},
pages = {1-19},
url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0258477},
doi = {https://doi.org/10.1371/journal.pone.0258477}
}
|
|
Experimental demonstration of accurate Bragg peak localization with ionoacoustic tandem phase detection (iTPD) H.P. Wieser, Y. Huang, J. Schauer, J. Lascaud, M. Würl, S. Lehrack, D. Radonic, M. Vidal, J. Hérault, A. Chmyrov, V. Ntziachristos, W. Assmann, K. Parodi and G. Dollinger; Physics in Medicine &mathsemicolon Biology 66 (24) (2021) 245020. |
| Abstract: Accurate knowledge of the exact stopping location of ions inside the patient would allow full exploitation of their ballistic properties for patient treatment. The localized energy deposition of a pulsed particle beam induces a rapid temperature increase of the irradiated volume and leads to the emission of ionoacoustic (IA) waves. Detecting the time-of-flight (ToF) of the IA wave allows inferring information on the Bragg peak location and can henceforth be used for in-vivo range verification. A challenge for IA is the poor signal-to-noise ratio at clinically relevant doses and viable machines. We present a frequency-based measurement technique, labeled as ionoacoustic tandem phase detection (iTPD) utilizing lock-in amplifiers. The phase shift of the IA signal to a reference signal is measured to derive the ToF. Experimental IA measurements with a 3.5 MHz lead zirconate titanate (PZT) transducer and lock-in amplifiers were performed in water using 22 MeV proton bursts. A digital iTPD was performed in-silico at clinical dose levels on experimental data obtained from a clinical facility and secondly, on simulations emulating a heterogeneous geometry. For the experimental setup using 22 MeV protons, a localization accuracy and precision obtained through iTPD deviates from a time-based reference analysis by less than 15 μm. Several methodological aspects were investigated experimentally in systematic manner. Lastly, iTPD was evaluated in-silico for clinical beam energies indicating that iTPD is in reach of sub-mm accuracy for fractionated doses < 5 Gy. iTPD can be used to accurately measure the ToF of IA signals online via its phase shift in frequency domain. An application of iTPD to the clinical scenario using a single pulsed beam is feasible but requires further development to reach <1 Gy detection capabilities. |
BibTeX:
@article{Wieser2021,
author = {Wieser, H. P. and Huang, Y. and Schauer, J. and Lascaud, J. and Würl, M. and Lehrack, S. and Radonic, D. and Vidal, M. and Hérault, J. and Chmyrov, A. and Ntziachristos, V. and Assmann, W. and Parodi, K. and Dollinger, G.},
title = {Experimental demonstration of accurate Bragg peak localization with ionoacoustic tandem phase detection (iTPD)},
journal = {Physics in Medicine &mathsemicolon Biology},
publisher = {IOP Publishing},
type = {OpenAccess},
year = {2021},
volume = {66},
number = {24},
pages = {245020},
url = {https://iopscience.iop.org/article/10.1088/1361-6560/ac3ead},
doi = {https://doi.org/10.1088/1361-6560/ac3ead}
}
|
2018 |
|
Physics at the Munich Tandem Accelerator Laboratory G. Dollinger and T. Faestermann; Nuclear Physics News 28 (1) (2018) 5-12. |
| Abstract: The Tandem accelerator situated in Garching, just 20 km north of Munich, is of the “Emperor” (MP) series manufactured by High Voltage Engineering Corporation (HVEC). It delivered the first beams for experiments in 1970 and came close to its design voltage of 10 MV. In 1991 the tubes were exchanged to the extended version of HVEC. Routine operation at a terminal voltage of 14 MV was then possible. |
BibTeX:
@article{Dollinger2018,
author = {Günther Dollinger and Thomas Faestermann},
title = {Physics at the Munich Tandem Accelerator Laboratory},
journal = {Nuclear Physics News},
publisher = {Taylor & Francis},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2018},
volume = {28},
number = {1},
pages = {5-12},
url = {https://www.tandfonline.com/doi/full/10.1080/10619127.2018.1427405},
doi = {https://doi.org/10.1080/10619127.2018.1427405}
}
|
|
Physics at the Munich Tandem Accelerator Laboratory G. Dollinger and T. Faestermann; ArXiv (v2) (2018) . |
| 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. |
BibTeX:
@openaccess{Dollinger2018a,
author = {Günther Dollinger and Thomas Faestermann},
title = {Physics at the Munich Tandem Accelerator Laboratory},
journal = {ArXiv},
type = {OpenAccess},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2018},
number = {v2},
url = {https://arxiv.org/abs/1802.07057}
}
|
|
Radiation hardness testing of super-junction power mosfets by heavy ion induced see mapping M. Gerold, A. Bergmaier, C. Greubel, J. Reindl, G. Dollinger and M. Rüb; In: 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) , Proceedings of the International Symposium on the Physical and Failure Analysis of Integrated Circuits, IPFA 2018-July (2018) . |
| Abstract: In this work direct heavy ion mapping of Single Event Effect (SEE) and Single Event Burnout (SEB) of super-junction power MOSFETs utilizing a high energy (55MeV) carbon micro-beam is presented. The resulting maps are sub-structurally resolved. Effect location, signal level and possible connections to cosmic radiation events are discussed. |
BibTeX:
@inproceedings{Gerold2018,
author = {Gerold, M. and Bergmaier, A. and Greubel, C. and Reindl, J. and Dollinger, G. and Rüb, M.},
title = {Radiation hardness testing of super-junction power mosfets by heavy ion induced see mapping},
booktitle = {2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA)},
journal = {Proceedings of the International Symposium on the Physical and Failure Analysis of Integrated Circuits, IPFA},
type = {OpenAccess},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2018},
volume = {2018-July},
note = {cited By 0},
url = {https://ieeexplore.ieee.org/document/8452587},
doi = {https://doi.org/10.1109/IPFA.2018.8452587}
}
|
2017 |
|
SNAKE Optik C. Greubel; Private Communications (2017) . |
| Abstract: Im Folgenden sind ein paar, mitunter auch längliche Gedanken, zur Ionenoptik an SNAKE dargestellt. Die Gedanken sind getrieben vom Ziel limitierende Faktoren an SNAKE zu identifizieren und zu korrigieren. Das Niederschreiben wurde getrieben von der Notwendigkeit das gedachte zu ordnen und zu strukturieren um effzient Weiterdenken zu köonnen. Es hat sich gezeigt, dass man zur Analyse der Optik leider ein paar formale Grundlagen zur Beschreibung von Aberationen, aber auch von elektrischen und magnetischen Feldern sowie deren Wirkung benöotigt. Diese sind in Kap. 1 soweit notwendig zusammengefasst und werden in den weiteren Kapiteln auch verwendet. Insofern ist dies die Einstiegshüurde. In Kap. 2 wird die Methode zu Analyse und Vermessung von Strahlaberrationen vorgestellt. Die Kapitel 3-5 diskutieren dann individuelle Aberrationen und sind untereinander weitestgehend unabhängig. Die Analyse ist sicher nur eine Momentaufnahmen un noch nicht ausgereift. Schon gar nicht ist die Darstellung didaktisch optimiert oder ausgefeilt. Auch werden grammatikalische, orthographische, aber auch strukturelle Unzuläanglichkeiten gehäauft auftreten. |
BibTeX:
@manual{Greubel2017a,
author = {Christoph Greubel},
title = {SNAKE Optik},
journal = {Private Communications},
type = {Manual},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2017},
editor = {Christoph Greubel}
}
|
2016 |
|
Range Verification with Ionoacoustics: simulations and measurements at a clinical proton synchro-cyclotron S. Lehrack, W. Assmann, A. Maaß, K. Baumann, G. Dedes, S. Reinhardt, P. Thirolf, G. Dollinger, F.V. Stappen, J.V. de Walle, S. Henrotin, B. Reynders, D. Bertrand, D. Prieels and K. Parodi; Radiotherapy and Oncology 118 (2016) S66 - S67. |
| Abstract: The local temperature increase induced by ion energy deposition in tissue creates an "ionoacoustic" ultrasound signal, particularly at the dose maximum (Bragg peak). This signal may be used for range verification in ion beam therapy in the future, which is still an important challenge for this irradiation modality. This approach has recently been revisited by several groups in simulations, and by our group in simulations and also in proof-of-principle experiments with pulsed 20 MeV proton beams. Here we present new simulations and first measurements of the ionoacoustic signal produced in water by proton beams accelerated up to energies of 227 MeV at a clinical synchrocyclotron. |
BibTeX:
@article{Lehrack2016,
author = {S. Lehrack and W. Assmann and A. Maaß and K. Baumann and G. Dedes and S. Reinhardt and P. Thirolf and G. Dollinger and F. Vander Stappen and J. Van de Walle and S. Henrotin and B. Reynders and D. Bertrand and D. Prieels and K. Parodi},
title = {Range Verification with Ionoacoustics: simulations and measurements at a clinical proton synchro-cyclotron},
journal = {Radiotherapy and Oncology},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2016},
volume = {118},
pages = {S66 - S67},
note = {ICTR-PHE 2016, 15-19 February 2016, CICG, Geneva, Switzerland},
url = {http://www.sciencedirect.com/science/article/pii/S0167814016301359},
doi = {https://doi.org/10.1016/S0167-8140(16)30135-9}
}
|
2015 |
|
Ionoacoustic characterization of the proton Bragg peak with submillimeter accuracy W. Assmann, S. Kellnberger, S. Reinhardt, S. Lehrack, A. Edlich, P.G. Thirolf, M. Moser, G. Dollinger, M. Omar, V. Ntziachristos and K. Parodi; Medical Physics 42 (2) (2015) 567-574. |
| Abstract: Purpose: Range verification in ion beam therapy relies to date on nuclear imaging techniques which require complex and costly detector systems. A different approach is the detection of thermoacoustic signals that are generated due to localized energy loss of ion beams in tissue (ionoacoustics). Aim of this work was to study experimentally the achievable position resolution of ionoacoustics under idealized conditions using high frequency ultrasonic transducers and a specifically selected probing beam. Methods: A water phantom was irradiated by a pulsed 20 MeV proton beam with varying pulse intensity and length. The acoustic signal of single proton pulses was measured by different PZT-based ultrasound detectors (3.5 and 10 MHz central frequencies). The proton dose distribution in water was calculated by Geant4 and used as input for simulation of the generated acoustic wave by the matlab toolbox k-WAVE. Results: In measurements from this study, a clear signal of the Bragg peak was observed for an energy deposition as low as 10e12 eV. The signal amplitude showed a linear increase with particle number per pulse and thus, dose. Bragg peak position measurements were reproducible within ±30 μm and agreed with Geant4 simulations to better than 100 μm. The ionoacoustic signal pattern allowed for a detailed analysis of the Bragg peak and could be well reproduced by k-WAVE simulations. Conclusions: The authors have studied the ionoacoustic signal of the Bragg peak in experiments using a 20 MeV proton beam with its correspondingly localized energy deposition, demonstrating submillimeter position resolution and providing a deep insight in the correlation between the acoustic signal and Bragg peak shape. These results, together with earlier experiments and new simulations (including the results in this study) at higher energies, suggest ionoacoustics as a technique for range verification in particle therapy at locations, where the tumor can be localized by ultrasound imaging. This acoustic range verification approach could offer the possibility of combining anatomical ultrasound and Bragg peak imaging, but further studies are required for translation of these findings to clinical application. |
BibTeX:
@article{Assmann2015,
author = {Assmann, W. and Kellnberger, S. and Reinhardt, S. and Lehrack, S. and Edlich, A. and Thirolf, P. G. and Moser, M. and Dollinger, G. and Omar, M. and Ntziachristos, V. and Parodi, K.},
title = {Ionoacoustic characterization of the proton Bragg peak with submillimeter accuracy},
journal = {Medical Physics},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2015},
volume = {42},
number = {2},
pages = {567--574},
url = {http://scitation.aip.org/content/aapm/journal/medphys/42/2/10.1118/1.4905047},
doi = {https://doi.org/10.1118/1.4905047}
}
|
2013 |
|
High-accuracy fluence determination in ion beams using fluorescent nuclear track detectors J.-M. Osinga, M. Akselrod, R. Herrmann, V. Hable, G. Dollinger, O. Jäkel and S. Greilich; Radiation Measurements 56 (2013) 294-298. |
| Abstract: We present an approach to use Al2O3:C,Mg-based fluorescent nuclear track detectors (FNTDs) and confocal laser scanning microscopy as a semiautomatic tool for fluence measurements in clinical ion beams. The method was found to cover a linear energy transfer (LET) range from at least L∞(Al2O3) = 0.5 keV/μm to 61,000 keV/μm with a detection efficiency ≥99.83% (20 MeV protons) at particle fluences up to at least 5 × 107 per cm2. Our technique allows to determine the spatial fluence distribution on a microscopic scale and enables detailed track-by-track comparison studies between different fluence detectors. |
BibTeX:
@article{Osinga2013,
author = {Osinga, J.-M. and Akselrod, M.S. and Herrmann, R. and Hable, V. and Dollinger, G. and Jäkel, O. and Greilich, S.},
title = {High-accuracy fluence determination in ion beams using fluorescent nuclear track detectors},
booktitle = {Proceedings of the 8th International Conference on Luminescent Detectors and Transformers of Ionizing Radiation (LUMDETR 2012)},
journal = {Radiation Measurements},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2013},
volume = {56},
pages = {294--298},
url = {http://www.sciencedirect.com/science/article/pii/S1350448713000589},
doi = {https://doi.org/10.1016/j.radmeas.2013.01.035}
}
|
2012 |
|
Ultrahigh gain AlGaN/GaN high energy radiation detectors J.D. Howgate, M. Hofstetter, S.J. Schoell, M. Schmid, S. Schäfer, I. Zizak, V. Hable, C. Greubel, G. Dollinger, S. Thalhammer, M. Stutzmann and I.D. Sharp; physica status solidi (a) 209 (8) (2012) 1562-1567. |
| Abstract: Due to its remarkable tolerance to high energy ionizing radiation, GaN has recently attracted attention as a promising material for dosimetry applications. However, materials issues that lead to persistent photoconductivity, poor sensitivity, and requirements for large operational voltages have been hurdles to realization of the full potential of this material. Here we demonstrate that the introduction of a two-dimensional electron gas channel, through the addition of AlGaN/GaN heterointerfaces, can be used to create intrinsic amplification of the number of electrons that can be collected from single ionization events, yielding exceptionally large sensitivities in ultralow dose rate regimes. Furthermore, anomalous photo-responses, which severely limit response times of GaN-based devices, can be eliminated using these heterostructures. Measurements using focused monochromatic synchrotron radiation at 1-20 keV, as well as focused 20 MeV protons, reveal that these devices provide the capability for high sensitivity and resolution real time monitoring, which is competitive with and complementary to state-of-the-art detectors. Therefore, AlGaN/GaN heterostructure devices are extremely promising for future applications in fields ranging from high energy physics to medical imaging. |
BibTeX:
@article{Howgate2012,
author = {Howgate, J. D. and Hofstetter, M. and Schoell, S. J. and Schmid, M. and Schäfer, S. and Zizak, I. and Hable, V. and Greubel, C. and Dollinger, G. and Thalhammer, S. and Stutzmann, M. and Sharp, I. D.},
title = {Ultrahigh gain AlGaN/GaN high energy radiation detectors},
journal = {physica status solidi (a)},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2012},
volume = {209},
number = {8},
pages = {1562--1567},
url = {http://onlinelibrary.wiley.com/doi/10.1002/pssa.201228097/abstract},
doi = {https://doi.org/10.1002/pssa.201228097}
}
|
2004 |
|
Basic aspects of deep lithography with particles for the fabrication of micro-optical and micro-mechanical structures B. Volckaerts, P. Vynck, M. Vervaeke, L. Cosentino, P. Finocchiaro, P. Reichart, G. Datzmann, A. Hauptner, G. Dollinger, A. Hermanne and H. Thienpont; In: , M.J. Daele P. (Ed.), Proc. SPIE 5454, Micro-Optics: Fabrication, Packaging, and Integration 5454 (2004) 52-63 , SPIE. |
| Abstract: The strength of today's deep lithographic micro-machining technologies is their ability to fabricate monolithic building-blocks including optical and mechanical functionalities that can be precisely integrated in more complex photonic systems. In this contribution we present the physical aspects of Deep Lithography with ion Particles (DLP). We investigate the impact of the ion mass, energy and fluence on the developed surface profile to find the optimized irradiation conditions for different types of high aspect ratio micro-optical structures. To this aim, we develop a software program that combines the atomic interaction effects with the macroscopic beam specifications. We illustrate the correctness of our simulations with experimental data that we obtained in a collaboration established between the accelerator facilities at TUM, LNS and VUB. Finally, we review our findings and discuss the strengths and weaknesses of DLP with respect to Deep Lithography with X-rays (LIGA). |
BibTeX:
@inproceedings{Volckaerts2004,
author = {Volckaerts, B. and Vynck, P. and Vervaeke, M. and Cosentino, L. and Finocchiaro, P. and Reichart, P. and Datzmann, G. and Hauptner, A. and Dollinger, G. and Hermanne, A. and Thienpont, H.},
title = {Basic aspects of deep lithography with particles for the fabrication of micro-optical and micro-mechanical structures},
booktitle = {Proc. SPIE 5454, Micro-Optics: Fabrication, Packaging, and Integration},
publisher = {SPIE},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2004},
volume = {5454},
number = {52},
pages = {52--63},
editor = {Daele P., Mohr J.},
note = {cited By (since 1996)0},
url = {http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=845728},
doi = {https://doi.org/10.1117/12.547718}
}
|
2002 |
|
Electron-stimulated hydrogen desorption from diamond surfaces and its influence on the low-pressure synthesis of diamond C. Goeden and G. Dollinger; Applied Physics Letters 81 (26) (2002) 5027-5029. |
| Abstract: A total cross section σD = (5±2.6)×10e−18 cm2 is measured for electron-stimulated desorption (ESD) of deuterium from a boron-doped, deuterated diamond(100) surface at 5 eV incident electron energy. This large ESD cross section means a significant contribution of ESD to hydrogen abstraction reactions in microwave-driven chemical vapor deposition of diamond. The ESD cross section decreases when changing to a nitrogen-doped diamond. This change is suggested to be the reason for the reported influence of small concentrations of nitrogen or boron added to the process gas on diamond growth. |
BibTeX:
@article{Goeden2002,
author = {Goeden, C. and Dollinger, G.},
title = {Electron-stimulated hydrogen desorption from diamond surfaces and its influence on the low-pressure synthesis of diamond},
journal = {Applied Physics Letters},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2002},
volume = {81},
number = {26},
pages = {5027-5029},
url = {http://link.aip.org/link/?APL/81/5027/1},
doi = {https://doi.org/10.1063/1.1526460}
}
|
|
Electron stimulated desorption of negative ions: A time-of-flight experiment C. Goeden and G. Dollinger; Review of Scientific Instruments 73 (8) (2002) 3058-3064. |
| Abstract: We present a setup for stimulated desorption experiments of negative ions using low energy incident electrons and time-of-flight identification of the desorbed ions. It consists of a pulsed electron gun, an electrostatic focusing system, and a channel plate detector setup. Electron beams down to sub-eV energies can be used due to electrostatic shielding and the compensation of the earth’s magnetic field by a set of Helmholtz coils. The main advantage is the large acceptance for ions of all masses, energies, and desorption angles at the same time, which keeps measuring time reasonably short and allows us to gain information before degeneration of the irradiated sample occurs, even if weak desorption channels are investigated. We demonstrate the power of our setup with first results from a boron doped, (100)-oriented diamond sample, which is partly oxidized and partly hydrogenated with some water contaminations on it. Different binding states of oxygen are disclosed clearly by different desorption thresholds. The C–O binding on oxidized diamond forms a carbonyl group. The 1b_2 orbital of water can be seen in a O desorption threshold. The yield of negative hydrogen desorption shows a linear increase for incident electron energies higher than 13 eV. It results from a dipolar dissociation as has been published previously. |
BibTeX:
@article{Goeden2002a,
author = {Goeden, C. and Dollinger, G.},
title = {Electron stimulated desorption of negative ions: A time-of-flight experiment},
journal = {Review of Scientific Instruments},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2002},
volume = {73},
number = {8},
pages = {3058-3064},
url = {http://link.aip.org/link/?RSI/73/3058/1},
doi = {https://doi.org/10.1063/1.1491030}
}
|
|
Elektronisch stimulierte Wasserstoffdesorption von Diamantoberflächen Christian Goeden; Dissertation, Technische Universität München, 2002. |
| Abstract: Im Rahmen dieser Arbeit wurden zwei Instrumente zur stimulierten Desorption (ESD) negativer und positiver Ionen von Festkörperoberflächen unter Elektronenbeschuß (Anregungsenergie 0.5 - 300 eV) aufgebaut und betrieben. Damit wurde die stimulierte Wasserstoffdesorption von Diamantoberflächen untersucht. Die Ergebnisse werden in Bezug auf die technische Verwendbarkeit des Prozesses zum Bau einer brillanten Ionenquelle dargestellt. Darüberhinaus zeigen die Ergebnisse einen signifikanten Einfluß von ESD-Prozessen auf die Diamant-Niederdrucksynthese. Der lange bekannte Einfluß der Dotierung auf das Wachstum wird damit erklärbar. |
BibTeX:
@phdthesis{Goeden2002diss,
author = {Goeden, Christian},
title = {Elektronisch stimulierte Wasserstoffdesorption von Diamantoberflächen},
school = {Technische Universität München},
year = {2002},
url = {http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:91-diss2002072313551}
}
|
2001 |
|
Energy distribution of thermally emitted negative particles from type Ia diamond (100) C. Goeden and G. Dollinger; Diamond and Related Materials 10 (3-7) (2001) 496-499. |
| Abstract: This study explores the electron emission of natural, nitrogen-doped diamond at elevated temperatures. The diamond was resistively heated up to 870°C. Accruing negatively charged particles where accelerated by a bias voltage of 30 V and the energy distribution is measured. The electrons are analysed by an electrostatic deflection resulting in an energy resolution of 70 meV. A hydrogen-free surface at a base pressure of 2.0×10−9 mbar shows a very small emission. The energy distribution has its maximum at 2.5 eV and a FWHM of 0.52 eV. Beside the main emission peak, some smaller features are observable at higher energies. An atomic hydrogen supply at 1.9×10−5 mbar increases the emission by a factor of 30. With some delay to the hydrogen supply, a new low energy peak appears. The increase in intensity during hydrogen adsorption is explained by the occurrence of a negative electron affinity (NEA) of the hydrogen-covered diamond surface. The low-energy feature might be due to hydrogen ions, either desorbing from the surface or from charge transfer during collisions of gas phase hydrogen with the diamond surface. |
BibTeX:
@article{Goeden2001,
author = {Goeden, C. and Dollinger, G.},
title = {Energy distribution of thermally emitted negative particles from type Ia diamond (100)},
booktitle = {11th European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide},
journal = {Diamond and Related Materials},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2001},
volume = {10},
number = {3-7},
pages = {496--499},
url = {http://www.sciencedirect.com/science/article/pii/S0925963500004544},
doi = {https://doi.org/10.1016/S0925-9635(00)00454-4}
}
|
|
Particle-induced X-ray emission using high energy ions with respect to microprobe application O. Schmelmer, G. Dollinger, G. Datzmann, A. Hauptner, H.-J. Körner, P. Maier-Komor and P. Reichart; Nuclear Instruments and Methods in Physics Research Section B 179 (4) (2001) 469-479. |
| Abstract: Cross-sections for continuous and characteristic X-ray emission from heavy elements induced by 16 MeV protons and 70 MeV carbon ions are measured. The K- and L-line emission cross-sections are significantly increased compared to those of lower proton energies. The data are in satisfactory agreement with semi-empirical calculations for the proton beams while the experimental cross-sections for the 70 MeV carbon ions are up to one order of magnitude lower as calculated. The continuous X-ray background for protons can also be well described by theory taking into account the various sources of X-ray production by bremsstrahlung whereas again for carbon ions the background is overestimated by scaled theory. The sensitivity for particle-induced X-ray emission (PIXE) using high energy ions is within the same order of magnitude as that for the commonly used 1-3 MeV protons. However, 16 MeV proton beams may be better suited for PIXE analysis with submicron-sized beams due to the lower ion currents necessary from the increased X-ray production cross-sections and because the sample damage and lateral spread are reduced. |
BibTeX:
@article{Schmelmer2001,
author = {Schmelmer, O. and Dollinger, G. and Datzmann, G. and Hauptner, A. and Körner, H.-J. and Maier-Komor, P. and Reichart, P.},
title = {Particle-induced X-ray emission using high energy ions with respect to microprobe application},
journal = {Nuclear Instruments and Methods in Physics Research Section B},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2001},
volume = {179},
number = {4},
pages = {469--479},
url = {http://www.sciencedirect.com/science/article/pii/S0168583X01006085},
doi = {https://doi.org/10.1016/S0168-583X(01)00608-5}
}
|
2000 |
|
Electron stimulated desorption of negative hydrogen ions from diamond (100) C. Goeden, G. Dollinger and P. Feulner; Diamond and Related Materials 9 (3-6) (2000) 1164-1166. |
| Abstract: The electron stimulated desorption of negatively charged hydrogen ions from diamond surfaces is studied with respect to an application as a bright ion source. Desorption of macroscopic currents of negative ions from a diamond surface by stimulated desorption has been demonstrated recently. To determine the dependence of the ionization cross-section on electron affinity, an oxygen covered diamond was used as a model system for positive electron affinity diamond. On this surface, different amounts of deuterium have been adsorbed. The D− ionization cross-section has been proven to vary by one order of magnitude between 3.5×10−18 cm2 and 5×10−19 cm2 with hydrogen coverage of the surface. The energy distribution of desorbed negative ions has been measured by an electrostatic analyser. For the measured broad energy distribution, an attempt of an explanation is made. |
BibTeX:
@article{Goeden2000,
author = {Goeden, C. and Dollinger, G. and Feulner, P.},
title = {Electron stimulated desorption of negative hydrogen ions from diamond (100)},
journal = {Diamond and Related Materials},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {2000},
volume = {9},
number = {3-6},
pages = {1164--1166},
url = {http://www.sciencedirect.com/science/article/pii/S0925963599002915},
doi = {https://doi.org/10.1016/S0925-9635(99)00291-5}
}
|
1999 |
|
Electron stimulated desorption on diamond (100) as a negative hydrogen source C. Goeden and G. Dollinger; Applied Surface Science 147 (1-4) (1999) 107-113. |
| Abstract: The electron-stimulated desorption of negatively charged hydrogen ions from diamond surfaces is studied with respect to an application as a bright ion source. Bombarding an (100)-oriented, boron-doped single crystal diamond with 40-μA electrons at energies up to 12 keV, a maximum ion current of 700 pA negative hydrogen is obtained. A supply of 1.0×10−4 mbar atomic deuterium results in a steady-state ion current of 30 pA. The ionization cross section has been proven to vary one order of magnitude between 3.5×10−18 cm2 and 5×10−19 cm2 with hydrogen coverage of the surface. This effect might be caused by the changing electron affinity of the diamond. |
BibTeX:
@article{Goeden1999,
author = {Goeden, C. and Dollinger, G.},
title = {Electron stimulated desorption on diamond (100) as a negative hydrogen source},
journal = {Applied Surface Science},
school = {Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik, LRT 2 - Institut für Angewandte Physik und Messtechnik, Professur: Dollinger, Günther},
year = {1999},
volume = {147},
number = {1-4},
pages = {107--113},
url = {http://www.sciencedirect.com/science/article/pii/S0169433299000926},
doi = {https://doi.org/10.1016/S0169-4332(99)00092-6}
}
|