Дисертації з теми "Heavy ion beam"
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1
Takeiri, Yasuhiko. "Intense heavy negative-ion beam production and negative ion beam deposition." Kyoto University, 1988. http://hdl.handle.net/2433/162219.
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2
Penache, Dan Lucius. "Heavy ion beam transport in laser initiated high current gas discharge channels." Phd thesis, [S.l.] : [s.n.], 2002. http://elib.tu-darmstadt.de/diss/000245.
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3
Rojko, Roman. "New concepts for transverse beam stability in high-current heavy-ion synchrotrons." Phd thesis, Berlin : Dissertation.de, 2003. http://elib.tu-darmstadt.de/diss/000382.
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4
Neff, Stephan. "Heavy-ion beam transport in plasma channels transport properties and channel stability /." [S.l. : s.n.], 2005. http://elib.tu-darmstadt.de/diss/000561.
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5
Chen, Geng-Sheng. "Ion beam mixing of Mo/Al bilayer samples and thermal spike effects." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/94500.
Повний текст джерелаАнотація:
Metallic bilayer samples of Mo(400 Å)/ Al(substrate) were characterized using Rutherford Backscattering Spectroscopy after first being irradiated with Xe ion beam having an energy of 1.8 MeV. The computer code RUMP was then used to simulate the RBS spectra. The interdiffusion at the interface was considered in terms of thermal spike induced atomic migration. It was found that the coupling of the chemical effect with spike is significant with regard to mixing of the bilayer samples. Furthermore, in addition to the initial contamination of carbon atoms on the surface and at the interface, more carbon atoms were found to be picked up by the surface, this carbon w.as from the vacuum pumps and tended to migrate into the surface once irradiation dose exceeded 11 x 10¹⁵cm².
A semi-empirical model was developed for ion beam mixing taking into account collisional mixing and thermal spike effects, as well as the thermal spike shape. The collisional mixing part was accounted for by the Kinchin-Pease model, or, alternatively dynamic Monte Carlo simulation. For the thermal spike, the ion beam mixing parameter Dt/Φ was derived to be proportional to ( - FD /ΔHcoh)2+μ, where FD is the damage energy deposited per unit path length, ΔHcoh is the cohesive energy of the target materials, and µ is a constant dependent on the spike shape and point defect density in the spike regions. The thermal spike introduces a nonlinear effect in the mixing process, distinguishing itself from the linear effect of ballistic mixing. The shape of the thermal spike that best fit the experimental results depends on the magnitude of the cascade density. For relatively high density collisional cascades, where thermal spikes start to be important, it was found that a spherical spike model was more consistent with experimental measurements at low temperatures. However, for extremely high density collisional cascade regions, a cylindrical shaped spike gave better results.
The atomic migration energy in the spike regions is scaled by a factor of one out of 8.6 of cohesive energy. The migration mechanism was recognized to be interstitial-dominated one.M.S.
6
Manuel, Jack Elliot. "Design, Construction, and Application of an Electrostatic Quadrupole Doublet for Heavy Ion Nuclear Microprobe Research." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062819/.
Повний текст джерелаАнотація:
A nuclear microprobe, typically consisting of 2 - 4 quadrupole magnetic lenses and apertures serving as objective and a collimating divergence slits, focuses MeV ions to approximately 1 x 1 μm for modification and analysis of materials. Although far less utilized, electrostatic quadrupole fields similarly afford strong focusing of ions and have the added benefit of doing so independent of ion mass. Instead, electrostatic quadrupole focusing exhibits energy dependence on focusing ions. A heavy ion microprobe could extend the spatial resolution of conventional microprobe techniques to masses untenable by quadrupole magnetic fields. An electrostatic quadrupole doublet focusing system has been designed and constructed using several non-conventional methods and materials for a wide range of microprobe applications. The system was modeled using the software package "Propagate Rays and Aberrations by Matrices" which quantifies system specific parameters such as demagnification and intrinsic aberrations. Direct experimental verification was obtained for several of the parameters associated with the system. Details of the project and with specific applications of the system are presented.
7
Johnson, Samantha. "Optimizing the ion source for polarized protons." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&.
Повний текст джерелаАнотація:
Beams of polarized protons play an important part in the study of the spin dependence of the nuclear force by measuring the analyzing power in nuclear reactions. The source at iThemba LABS produces a beam of polarized protons that is pre-accelerated by an injector cyclotron (SPC2) to a energy of 8 MeV before acceleration by the main separated-sector cyclotron to 200 MeV for physics research. The polarized ion source is one of the two external ion sources of SPC2. Inside the ion source hydrogen molecules are dissociated into atoms in the dissociator and cooled to a temperature of approximately 30 K in the nozzle. The atoms are polarized by a pair of sextupole magnets and the nucleus is polarized by RF transitions between hyperfine levels in hydrogen atoms. The atoms are then ionized by electrons in the ionizer. The source has various sensitive devices, which influence beam intensity and polarization. Nitrogen gas is used to prevent recombination of atoms after dissociation. The amount of nitrogen and the temperature at which it is used plays a very important role in optimizing the beam current. The number of electrons released in the ionizer is influenced by the size and shape of the filament. Optimization of the source will ensure that beams of better quality (a better current and stability) are produced.
8
Crespo, Paulo. "Optimization of In-Beam Positron Emission Tomography for Monitoring Heavy Ion Tumor Therapy." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-28512.
Повний текст джерелаАнотація:
In-beam positron emission tomography (in-beam PET) is currently the only method for an in-situ monitoring of highly tumor-conformed charged hadron therapy. In such therapy, the clinical effect of deviations from treatment planning is highly minimized by implementing safety margins around the tumor and selecting proper beam portals. Nevertheless, in-beam PET is able to detect eventual, undesirable range deviations and anatomical modifications during fractionated irradiation, to verify the accuracy of the beam portal delivered and to provide the radiotherapist with an estimation of the difference in dosage if the treatment delivered differs from the planned one. In a first study within this work, a set of simulation and fully-3D reconstruction routines shows that minimizing the opening angle of a cylindrical camera is determinant for an optimum quality of the in-beam PET images. The study yields two favorite detector geometries: a closed ring or a dual-head tomograph with narrow gaps. The implementation of either detector geometry onto an isocentric, ion beam delivery (gantry) is feasible by mounting the PET scanner at the beam nozzle. The implementation of an in-beam PET scanner with the mentioned detector geometries at therapeutic sites with a fixed, horizontal beam line is also feasible. Nevertheless, knowing that previous in-beam PET research in Berkeley was abandoned due to detector activation (Bismuth Germanate, BGO), arising most probably from passive beam shaping contaminations, the proposed detector configurations had to be tested in-beam. For that, BGO was substituted with a state-of-the-art scintillator (lutetium oxyorthosilicate, LSO) and two position sensitive detectors were built. Each detector contains 32 pixels, consisting of LSO finger-like crystals coupled to avalanche photodiode arrays (APDA). In order to readout the two detectors operated in coincidence, either in standalone mode or at the GSI medical beam line, a multi-channel, zero-suppressing free, list mode data acquisition system was built.The APDA were chosen for scintillation detection instead of photomultiplier tubes (PMT) due to their higher compactness and magnetic field resistance. A magnetic field resistant detector is necessary if the in-beam PET scanner is operated close to the last beam bending magnet, due to its fringe magnetic field. This is the case at the isocentric, ion beam delivery planned for the dedicated, heavy ion hospital facility under construction in Heidelberg, Germany. In-beam imaging with the LSO/APDA detectors positioned at small target angles, both upbeam and downbeam from the target, was successful. This proves that the detectors provide a solution for the proposed next-generation, improved in-beam PET scanners. Further confirming this result are germanium-detector-based, spectroscopic gamma-ray measurements: no scintillator activation is observed in patient irradiation conditions. Although a closed ring or a dual-head tomograph with narrow gaps is expected to provide improved in-beam PET images, low count rates in in-beam PET represent a second problem to image quality. More importantly, new accelerator developments will further enhance this problem to the point of making impossible in-beam PET data taking if the present acquisition system is used. For these reasons, two random-suppression methods allowing to collect in-beam PET events even during particle extraction were tested. Image counts raised almost twofold. This proves that the methods and associated data acquisition technique provide a solution for next-generation, in-beam positron emission tomographs installed at synchrotron or cyclotron radiotherapy facilities.
9
Crespo, Paulo. "Optimization of In-Beam Positron Emission Tomography for Monitoring Heavy Ion Tumor Therapy." Forschungszentrum Rossendorf, 2006. https://hzdr.qucosa.de/id/qucosa%3A21679.
Повний текст джерелаАнотація:
In-beam positron emission tomography (in-beam PET) is currently the only method for an in-situ monitoring of highly tumor-conformed charged hadron therapy. In such therapy, the clinical effect of deviations from treatment planning is highly minimized by implementing safety margins around the tumor and selecting proper beam portals. Nevertheless, in-beam PET is able to detect eventual, undesirable range deviations and anatomical modifications during fractionated irradiation, to verify the accuracy of the beam portal delivered and to provide the radiotherapist with an estimation of the difference in dosage if the treatment delivered differs from the planned one. In a first study within this work, a set of simulation and fully-3D reconstruction routines shows that minimizing the opening angle of a cylindrical camera is determinant for an optimum quality of the in-beam PET images. The study yields two favorite detector geometries: a closed ring or a dual-head tomograph with narrow gaps. The implementation of either detector geometry onto an isocentric, ion beam delivery (gantry) is feasible by mounting the PET scanner at the beam nozzle. The implementation of an in-beam PET scanner with the mentioned detector geometries at therapeutic sites with a fixed, horizontal beam line is also feasible. Nevertheless, knowing that previous in-beam PET research in Berkeley was abandoned due to detector activation (Bismuth Germanate, BGO), arising most probably from passive beam shaping contaminations, the proposed detector configurations had to be tested in-beam. For that, BGO was substituted with a state-of-the-art scintillator (lutetium oxyorthosilicate, LSO) and two position sensitive detectors were built. Each detector contains 32 pixels, consisting of LSO finger-like crystals coupled to avalanche photodiode arrays (APDA). In order to readout the two detectors operated in coincidence, either in standalone mode or at the GSI medical beam line, a multi-channel, zero-suppressing free, list mode data acquisition system was built.The APDA were chosen for scintillation detection instead of photomultiplier tubes (PMT) due to their higher compactness and magnetic field resistance. A magnetic field resistant detector is necessary if the in-beam PET scanner is operated close to the last beam bending magnet, due to its fringe magnetic field. This is the case at the isocentric, ion beam delivery planned for the dedicated, heavy ion hospital facility under construction in Heidelberg, Germany. In-beam imaging with the LSO/APDA detectors positioned at small target angles, both upbeam and downbeam from the target, was successful. This proves that the detectors provide a solution for the proposed next-generation, improved in-beam PET scanners. Further confirming this result are germanium-detector-based, spectroscopic gamma-ray measurements: no scintillator activation is observed in patient irradiation conditions. Although a closed ring or a dual-head tomograph with narrow gaps is expected to provide improved in-beam PET images, low count rates in in-beam PET represent a second problem to image quality. More importantly, new accelerator developments will further enhance this problem to the point of making impossible in-beam PET data taking if the present acquisition system is used. For these reasons, two random-suppression methods allowing to collect in-beam PET events even during particle extraction were tested. Image counts raised almost twofold. This proves that the methods and associated data acquisition technique provide a solution for next-generation, in-beam positron emission tomographs installed at synchrotron or cyclotron radiotherapy facilities.
10
Franich, Rick, and rick franich@rmit edu au. "Monte Carlo Simulation of Large Angle Scattering Effects in Heavy Ion Elastic Recoil Detection Analysis and Ion Transmission Through Nanoapertures." RMIT University. Applied Sciences, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080212.121837.
Повний текст джерелаАнотація:
Heavy Ion Elastic Recoil Detection Analysis (HIERDA) is a versatile Ion Beam Analysis technique well suited to multi-elemental depth profiling of thin layered structures and near-surface regions of materials. An existing limitation is the inability to accurately account for the pronounced broadening and tailing effects of multiple scattering typically seen in HIERDA spectra. This thesis investigates the role of multiple large angle scattering in heavy ion applications such as HIERDA, and seeks to quantify its contribution to experimental output. This is achieved primarily by the development of a computer simulation capable of predicting these contributions and using it to classify and quantify the interactions that cause them. Monte Carlo ion transport simulation is used to generate simulated HIERDA spectra and the results are compared to experimental data acquired using the Time of Flight HIERDA facility at the Australian Nuclear Science and Technology Organisat ion. A Monte Carlo simulation code was adapted to the simulation of HIERDA spectra with considerable attention on improving the modelling efficiency to reduce processing time. Efficiency enhancements have achieved simulation time reductions of two to three orders of magnitude. The simulation is shown to satisfactorily reproduce the complex shape of HIERDA spectra. Some limitations are identified in the ability to accurately predict peak widths and the absolute magnitude of low energy tailing in some cases. The code is used to identify the plural scattering contribution to the spectral features under investigation, and the complexity of plurally scattered ion and recoil paths is demonstrated. The program is also shown to be useful in the interpretation of overlapped energy spectra of elements of similar mass whose signals cannot be reliably separated experimentally. The effect of large angle scattering on the transmission of heavy ions through a nano-scale aperture mask, used to collimate an ion beam to a very small beam spot, is modelled using a version of the program adapted to handle the more complex geometry of the aperture mask. The effectiveness of nano-aperture collimation was studied for a variety of ion-energy combinations. Intensity, energy, and angular distributions of transmitted ions were calculated to quantify the degree to which scattering within the mask limits the spatial resolution achievable. The simulation successfully predicted the effect of misaligning the aperture and the beam, and the result has subsequently been observed experimentally. Transmitted ion distributions showed that the higher energy heavier ions studied are more effectively collimated than are lower energy lighter ions. However, there is still a significant probability of transmission of heavy ions with substantial residual energy beyond the perimeter of the aperture. For the intended application, ion beam lithography, these ions are likely to be problematic. The results indicate that medium energy He ions are the more attractive option, as the residual energy of scattered transmitted ions can be more readily managed by customising the etching process. Continuing research by experimentalists working in this area is proceeding in this direction as a result of the conclusions from this work.
11
Khalil, Ali Saied, and askhalil2004@yahoo com. "Heavy-Ion-Irradiation-Induced Disorder in Indium Phosphide and Selected Compounds." The Australian National University. Research School of Information Sciences and Engineering, 2007. http://thesis.anu.edu.au./public/adt-ANU20070716.140841.
Повний текст джерелаАнотація:
Indium phosphide (InP) is an important III-V compound, with a variety of applications, for example, in light emitting diodes (LED), InP based photonic crystals and in semiconductor lasers, heterojunction bipolar transistors in integrated circuit applications and in transistors for microwave and millimeter-wave systems. The optical and electrical properties of this compound can be further tailored by ion implantation or prospectively by swift heavy ion beams.
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Thus knowledge of ion-induced disorder in this material is of important fundamental and practical interest. However, the disorder produced during heavy ion irradiation and the subsequent damage accumulation and recovery in InP is far from being completely understood. In terms of the damage accumulation mechanisms, the conclusions drawn in the numerous studies performed have often been in conflict with one another. A factor contributing to the uncertainties associated with these conflicting results is a lack of information and direct observation of the building blocks leading to the ultimate damage created at high ion fluences as an amorphous layer. These building blocks formed at lower fluence regimes by single ion impacts can be directly observed as isolated disordered zones and ion tracks for low energy and swift heavy ion irradiation, respectively.
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The primary aim of this work has thus been to obtain a better understanding of the disorder in this material through direct observations and investigation of disorder produced by individual heavy ions in both energy regimes (i.e. elastic and inelastic energy deposition regimes) especially with low ion fluence irradiations. In this thesis the heavy ion induced disorder introduced by low energy Au ions (100 keV Au+) and high energy Au (200 MeV Au+16) ion irradiation in InP were investigated using Transmission Electron Microscopy (TEM), Rutherford Backscattering Spectrometry (RBS/C) and Atomic Force Microscopy (AFM).
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The accumulation of damage due to disordered zones and ion tracks is described and discussed for both low energy and swift ion irradiation respectively.
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The in-situ TEM annealing of disordered zones created by 100 keV Au+ ion irradiation shows that these zones are sensitive to electron beam irradiation and anneal under electron energies not sufficient to elastically displace lattice atoms, i.e. subthreshold energies for both constituent atoms In and P.
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Ion tracks due to swift heavy ion irradiation were observed in this material and the interesting track morphology was described and discussed. The surface nanotopographical changes due to increasing fluence of swift heavy ions were observed by AFM where the onset of large increase in surface roughness for fluences sufficient to cause complete surface amorphization was observed.
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In addition to InP, the principle material of this project, a limited amount of TEM observation work has been performed on several other important compounds (apatite and monazite) irradiated by 200 MeV Au+ ions for comparative purposes. Again the observed segmental morphology of ion tracks were shown and possible track formation scenario and structure were discussed and similarities were drawn to the previously observed C60 cluster ion tracks in CaF2 as more knowledge and data base exist about defect dynamics and formation in that material.
12
Rojko, Roman [Verfasser]. "New concepts for transverse beam stability in high-current heavy-ion synchrotrons / von Roman Rojko." Berlin : dissertation.de, 2003. http://d-nb.info/969655665/34.
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13
Anson, Christopher Daniel. "Energy dependent Hanbury Brown - Twiss interferometry and the freeze-out eccentricity of heavy ion collisions at STAR." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1387753475.
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14
Rizzo, Carmelo. "Symmetry Energy Effects in Low Energy Heavy Ion Collisions with Exotic Beams." Thesis, Università degli Studi di Catania, 2011. http://hdl.handle.net/10761/124.
Повний текст джерелаАнотація:
We investigate the reaction path followed by Heavy Ion Collisions with exotic nuclear beams at low energies. The evolution of the system is described by a Stochastic Mean Field transport equation (SMF), where two parameterizations for the density dependence of symmetry energy (Asysoft and Asystiff) are implemented, allowing one to explore the sensitivity of the results to this ingredient of the nuclear interaction.
We report the properties of the prompt dipole radiation, produced via a collective bremsstrahlung mechanism, in fusion reactions with exotic beams. We show that the gamma yield is sensitive to the density dependence of the symmetry energy below/around saturation. Moreover we find that the angular distribution of the emitted photons from such fast collective mode can represent a sensitive probe of its excitation mechanism and of fusion dynamics in the entrance channel. We will focus on the interplay between reaction mechanisms, fusion vs. break-up, that in exotic systems is expected to be influenced by the symmetry energy term at densities around the normal value. The new method described here, based on the event by event evolution of phase space Quadrupole collective modes will nicely allow to extract the fusion probability at relatively early times, when the transport results are reliable. Fusion probabilities for reactions induced by 132Sn on 64,58Ni targets at 10 AMeV are evaluated. We obtain larger fusion cross sections for the more n-rich composite system, and, for a given reaction, in the Asysoft choice. A collective charge equilibration mechanism (the Dynamical Dipole) is revealed in both fusion and break-up events, depending on the stiffness of the symmetry term just below saturation.
Finally we investigate the effect of the mass asymmetry in the entrance channel for systems with the same overall isospin content and similar initial charge asymmetry. As expected we find reduced fusion probabilities for the more mass symmetric case, while the DDR strength appears not much affected. This is a nice confirmation of the prompt nature of such collective isovector mode.
15
Kupka, Katharina [Verfasser], Christina [Akademischer Betreuer] Trautmann, and Wolfgang [Akademischer Betreuer] Ensinger. "Intense heavy ion beam-induced effects in carbon-based stripper foils / Katharina Kupka. Betreuer: Christina Trautmann ; Wolfgang Ensinger." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2016. http://d-nb.info/1112333118/34.
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16
Nigam, Mohit. "The Stopping of Energetic Si, P and S Ions in Ni, Cu, Ge and GaAs Targets." Thesis, University of North Texas, 2001. https://digital.library.unt.edu/ark:/67531/metadc3004/.
Повний текст джерелаАнотація:
Accurate knowledge of stopping powers is essential for these for quantitative analysis and surface characterization of thin films using ion beam analysis (IBA). These values are also of interest in radiobiology and radiotherapy, and in ion- implantation technology where shrinking feature sizes puts high demands on the accuracy of range calculations. A theory that predicts stopping powers and ranges for all projectile-target combinations is needed. The most important database used to report the stopping powers is the SRIM/TRIM program developed by Ziegler and coworkers. However, other researchers report that at times, these values differ significantly from experimental values. In this study the stopping powers of Si, P and S ions have been measured in Ni, Cu, Ge and GaAs absorbers in the energy range ~ 2-10 MeV. For elemental films of Ni, Cu and Ge, the stopping of heavy ions was measured using a novel ERD (Elastic Recoil Detection) based technique. In which an elastically recoiled lighter atom is used to indirectly measure the energy of the incoming heavy ion using a surface barrier detector. In this way it was possible to reduce the damage and to improve the FWHM of the detector. The results were compared to SRIM-2000 predictions and other experimental measurements. A new technique derived from Molecular Beam Epitaxy (MBE) was developed to prepare stoichiometric GaAs films on thin carbon films for use in transmission ion beam experiments. The GaAs films were characterized using X-ray Photoelectron Spectroscopy (XPS) and Particle Induced X-ray Emission (PIXE). These films were used to investigate the stopping powers of energetic heavy ions in GaAs and to provide data for the calculation of Bethe-Bloch parameters in the framework of the Modified Bethe-Bloch theory. As a result of this study, stopping power data are available for the first time for Si and P ions in the energy range 2-10 MeV stopping in GaAs absorbers.
17
Katrík, Peter [Verfasser], Dieter [Akademischer Betreuer] Hoffmann, and Christina [Akademischer Betreuer] Trautmann. "Activation analysis of heavy ion accelerator constructing materials and validation of beam-loss criteria / Peter Katrík ; Dieter Hoffmann, Christina Trautmann." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/1140586688/34.
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18
Shanmuganathan, Prashanth. "FIRST MOMENT OF AZIMUTHAL ANISOTROPY IN AU+AU COLLISIONS FROM THE BEAM ENERGY SCAN AT THE RELATIVISTIC HEAVY ION COLLIDER." Kent State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1465395347.
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19
Kovalenko, Oleksandr [Verfasser], and Andrey [Akademischer Betreuer] Surzhykov. "Ion optics and beam dynamics optimization at the HESR storage ring for the SPARC experiments with highly charged heavy ions / Oleksandr Kovalenko ; Betreuer: Andrey Surzhykov." Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://d-nb.info/1180500512/34.
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20
Imran, Muhammad Verfasser], Dieter [Akademischer Betreuer] [Hoffmann, and Norbert [Akademischer Betreuer] Pietralla. "Study of Heavy Ion Beam Interaction with High Energy Laser Produced Plasmas / Muhammad Imran. Betreuer: Dieter H. H. Hoffmann ; Norbert Pietralla." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2011. http://d-nb.info/1105563189/34.
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21
Grieser, Jochen Michael [Verfasser], Jürgen [Akademischer Betreuer] Adamy, and Harald [Akademischer Betreuer] Klingbeil. "Beam Phase Feedback in a Heavy-Ion Synchrotron with Dual-Harmonic Cavity System / Jochen Michael Grieser. Betreuer: Jürgen Adamy ; Harald Klingbeil." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2015. http://d-nb.info/1112268812/34.
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22
Imran, Muhammad [Verfasser], Dieter [Akademischer Betreuer] Hoffmann, and Norbert [Akademischer Betreuer] Pietralla. "Study of Heavy Ion Beam Interaction with High Energy Laser Produced Plasmas / Muhammad Imran. Betreuer: Dieter H. H. Hoffmann ; Norbert Pietralla." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2011. http://nbn-resolving.de/urn:nbn:de:tuda-tuprints-26969.
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23
Grieser, Jochen M. [Verfasser], Jürgen [Akademischer Betreuer] Adamy, and Harald [Akademischer Betreuer] Klingbeil. "Beam Phase Feedback in a Heavy-Ion Synchrotron with Dual-Harmonic Cavity System / Jochen Michael Grieser. Betreuer: Jürgen Adamy ; Harald Klingbeil." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2015. http://nbn-resolving.de/urn:nbn:de:tuda-tuprints-46340.
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24
Salamat, Cabanos Cerrone. "Molecular and Structural Analysis of Peanut Allergens and Development of a Peanut Variety Lacking Major Allergens by Heavy-ion Beam Irradiation." Kyoto University, 2011. http://hdl.handle.net/2433/142321.
Повний текст джерелаАнотація:
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第16123号
農博第1859号
新制||農||989(附属図書館)
学位論文||H23||N4593(農学部図書室)
28702
京都大学大学院農学研究科農学専攻
(主査)教授 裏出 令子, 教授 松村 康生, 教授 奥本 裕
学位規則第4条第1項該当
25
Sellner, Stefan [Verfasser], and Joachim [Akademischer Betreuer] Ullrich. "Simulations, Optimizations, and Microdosimetric Measurements of Beam Quality for Heavy-Ion Tumor Therapy. A charged (particle) issue. / Stefan Sellner ; Betreuer: Joachim Ullrich." Heidelberg : Universitätsbibliothek Heidelberg, 2013. http://d-nb.info/1177810581/34.
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26
Anzenberg, Vered. "Do heavy ions induce the bystander effect? : study to determine the induction of the bystander effect from Fe ion beam compared to X-rays in human keratinocytes." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34458.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2005.Includes bibliographical references (leaves 62-65).
The bystander effect is the observation that non-irradiated cells near a cell traversed by radiation express biological responses such as micronuclei formation and genomic instability. Most published studies of the bystander effect have been conducted using alpha particles, a high LET radiation. A few studies have been done with low LET radiation. This project studies the bystander effect from both low LET x-rays and high LET Fe particle beam irradiation. Using a transwell insert system, the bystander effect was studied in hTERT immortalized human keratinocytes. Cells are plated in a 6-well plate and in a companion permeable membrane insert. Cells in the 6-well plate are irradiated using conventional 250 kVp X-rays or 1000 MeV/nucleon Fe ion beam, LET of 151 keV/pm, from the NASA Space Radiation Laboratory at Brookhaven National Lab. After irradiation, inserts are immediately placed into the 6 well plate so that the irradiated and unirradiated cells are sharing medium but are not in contact. For both beams, frequency of micronuclei, chromatin bridges, and p21 wafl induction as well as cell cycle phase analysis were determined in both directly irradiated and bystander cells from 0.1 Gy to 5 Gy. From x-rays, a two-fold bystander effect at 24 h after irradiation with elevated p21' wafl induction and micronuclei was seen but in Fe ion irradiation, the p21 wafl bystander effect was delayed to 40-50 h after irradiation and no MN bystander effect was observed.
(cont.) Cell cycle analysis showed a slight G2 arrest in keratinocytes 5 h after x-rays but a strong G2 arrest until 40-50 h was seen after Fe ion irradiation. Bystander keratinocytes co-cultured with directly irradiated human fibroblasts AGO 1522 cells showed a two-fold p21 wafl and MN bystander effect 24 h after x-rays, and a potential 2-fold MN bystander effect 50 h after Fe ions. Bystander AGO1522 cells co-cultured with directly irradiated keratinocytes showed a two-fold MN bystander effect 24 h after x-rays, but no MN bystander response was seen at any time points studied from Fe ions. Striking differences in the bystander response were shown from the two radiation types, but the reason remains to be clarified.
by Vered Anzenberg.
S.M.
27
Hollmark, Malin. "Absorbed dose and biological effect in light ion therapy." Doctoral thesis, Stockholm : Medical Radiation Physics, Stockholm university together with KI, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7756.
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Sanba, Abdallah. "Interaction d'un faisceau d'ions lourds (**(12)c**(4+)) avec un plasma dense d'hydrogene." Orléans, 1988. http://www.theses.fr/1988ORLE2048.
Повний текст джерелаАнотація:
Etude de l'interaction d'un faisceau d'ions de carbone (**(12)c**(4+) de 24 mev) avec un plasma d'hydrogene caractarise par une densite de l'ordre de 10**(17) cm**(-3) et une temperature de 1 a 4 ev. Le plasma est produit par une decharge lineaire et differentes methodes de diagnostic sont utilisees. Le principe de l'experience consiste a placer le plasma sur une ligne de l'accelerateur tandem de l'i. P. N. D'orsay et a mesurer la perte de vitesse des ions dans le plasma. Les resultats obtenus sont en excellent accord avec la theorie, la perte d'energie des ions dans le plasma est 2 a 3 fois plus forte que dans la matiere froide de meme densite
29
Andgren, Karin. "Studies of collective phenomena in neutron deficient nuclei : by means of lifetime measurements, angular correlation measurements and the recoil decay tagging technique /." Doctoral thesis, KTH, Fysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4693.
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Kemp, Andreas J. "Magnetized cylindrical implosions driven by heavy ion beams." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962128287.
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Nakata, Yoshihiko. "Imaging Mass Spectrometry with MeV Heavy Ion Beams." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/124537.
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32
Alalawi, Huda. "INVESTIGATION OF NUCLEAR COMPRESSION IN THE AMPT MODELOF NUCLEUS-NUCLEUS COLLISIONS." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1543405727739039.
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Samuelsson, Katarina. "Adiabatic capture of heavy ion beams in RF buckets." Thesis, KTH, Rymd- och plasmafysik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91542.
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Henestroza, Enrique. "Generation, transport and focusing of high-brightness heavy ion beams." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37211.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2006.Includes bibliographical references (p. 195-201).
The Neutralized Transport Experiment (NTX) has been built at the Heavy Ion Fusion Virtual National Laboratory. NTX is the first successful integrated beam system experiment that explores various physical phenomena, and determines the final spot size of a high intensity ion beam on a scaled version of a Heavy Ion Fusion driver. The final spot size is determined by the conditions of the beam produced in the injector, the beam dynamics in the focusing lattice, and the plasma neutralization dynamics in the final transport. A high brightness ion source using an aperturing technique delivers 25 mA of single charged potassium ion beam at 300 keV and a normalized edge emittance of 0.05 r-mm-mr. The ion beam is injected into a large bore magnetic quadrupole lattice, which produces a 20 mm radius beam converging at 20 mr. The converging ion beam is further injected into a plasma neutralization drift section where it is compressed ballistically down to a 1 mm spot size.
(cont.) NTX provides the first experimental proof of plasma neutralized ballistic transport of a space-charge dominated ion beam, the information about higher order aberration effects on the spot size, the validation of numerical tools based on excellent agreement between measurements and numerical simulations over a broad parameter regime, and the development of new diagnostics to study the ion beam dynamics. The theoretical and experimental results are presented on the beam dynamics in the ion diode, downstream quadrupole lattice, and final neutralized transport.
by Enrique Henestroza.
Ph.D.
35
Kuhlman, Anthony Joseph. "The beginning and end of relativistic heavy ion collisions using uranium beams and Bose-Einstein correlations as probes of the collision fireball /." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1185456181.
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Constantin, Carmen. "Multiple weak shock waves induced by heavy ion beams in solid matter." Phd thesis, [S.l.] : [s.n.], 2002. http://elib.tu-darmstadt.de/diss/000225.
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Varentsov, Dmitry. "Energy loss dynamics of intense heavy ion beams interacting with dense matter." [S.l. : s.n.], 2002. http://elib.tu-darmstadt.de/diss/000323.
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38
Mohammadi, Saeed. "Studies of N~Z~28 nuclei with stable and radioactive heavy ion beams." Thesis, University of Surrey, 1997. http://epubs.surrey.ac.uk/844250/.
Повний текст джерелаАнотація:
This thesis details the study of N~Z~28 nuclei obtained using the fusion evaporation reactions 19Ne +40Ca at a beam energy of 70 MeV and 24Mg-40Ca at a beam energy of 65 MeV. The 19Ne data constitute the first tests of a neutron-deficient Radioactive Ion Beam (RIB) for high-spin nuclear spectroscopy. The radioactive Ne beam was supplied by the coupled cyclotrons at the Louvain-la-Neuve facility, Belgium. Emitted gamma-rays were detected by an array of 7 TESSA-style Ge-detectors in the backward hemisphere in two rings. A degree of channel selection was also allowed by identifying evaporated charged particles with an array of 128 silicon-strip detectors (LEDA array). Background subtraction of radiation from the decay of the beam was achieved using the timing properties of the pulsed beam and through particle detection using the LEDA charged particle array Information on the relative evaporation residue cross-sections was obtained and the problems associated with performing such experiments in a high radioactive background environment are addressed. New information on the high spin states of 58Ni was obtained using the reaction 40Ca (24Mg, alpha2p), performed at the ATLAS facility at Argonne National Laboratory. Emitted 7-rays were detected by high efficiency AYEBALL array which consisted of 18 EUROGAM and TESSA-style Compton suppressed Ge-detectors in four annular rings. Channel selection is demonstrated by use of (a) mass selection using the Argonne Fragment Mass Analyser (FMA), (b) a split anode ionization chamber at the back of the FMA, and (c) an array of 11 neutron detectors in a ring at forward angles. The effectiveness of using recoil-gated gamma coincidence data for the study of nuclear structure in neutron-deficient nuclei close to the proton drip-line is shown. The excited states of 58Ni are compared with OXBASH shell model calculations and the problems associated with forming high angular momentum states in the limited valence space are addressed.
39
Ding, Johannes [Verfasser], Markus [Akademischer Betreuer] Roth, and Oliver [Akademischer Betreuer] Boine-Frankenheim. "Generation, Handling and Transport of Laser-Driven Heavy Ion Beams / Johannes Ding ; Markus Roth, Oliver Boine-Frankenheim." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2018. http://d-nb.info/1172415528/34.
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Kuhlman, Anthony Joseph Jr. "The beginning and end of heavy ion collisions: using uranium beams and Bose-Einstein correlations as probes of the collision fireball." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1185456181.
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41
Hähnel, Jan Hendrik [Verfasser], Ulrich [Gutachter] Ratzinger, and Joachim [Gutachter] Jacoby. "Development of an IH-type linac for the acceleration of high current heavy ion beams / Jan Hendrik Hähnel ; Gutachter: Ulrich Ratzinger, Joachim Jacoby." Frankfurt am Main : Universitätsbibliothek Johann Christian Senckenberg, 2017. http://d-nb.info/1137944528/34.
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Liatard, Éric. "Mesures de sections efficaces totales de réaction avec des faisceaux d'ions lourds stables et radioactifs par la méthode du rayonnement associé." Grenoble 1, 1989. http://www.theses.fr/1989GRE10143.
Повний текст джерелаАнотація:
Nous avons mis au point une nouvelle methode de mesure directe de sections efficaces totales de reaction fondee sur l'utilisation d'un detecteur 4 pi modulaire. Dans un premier temps, des mesures ont ete effectuees avec des faisceaux d'ions lourds delivres par les accelerateurs sara et ganil dans la gamme d'energie 30-80 mev/u. Nous avons ensuite adapte notre dispositif aux mesures avec des faisceaux secondaires radioactifs (ligne lise du ganil). Les resultats obtenus couvrent une large gamme de projectiles legers comprenant des isotopes exotiques situes a la limite de la stabilite vis-a-vis de l'emission de neutrons. A partir des sections efficaces totales de reaction, les rayons carres moyens de ces projectiles sont calcules a l'aide d'un formalisme microscopique simple dont la validite est demontree par les resultats obtenus avec des faisceaux stables. Malgre la presence d'effets de structure marques (n pair- n impair), l'ensemble des isotopes etudies presente un rayon carre moyen normal excepte le #1#1be, le #1#4be et le #1#7b. Enfin, en utilisant les resultats de recents calculs haartree-fock, il est possible de determiner, a partir de nos donnees experimentales, les rayons carres moyens des distributions de neutrons des projectiles de n pairs. Ces rayons se comparent favorablement aux valeurs theoriques issues du meme calcul hartree-fock, excepte pour les cas ou l'extension spatiale des neutrons est tres importante (#1#4be et #1#7b)
43
Koser, Daniel [Verfasser], Holger [Akademischer Betreuer] Podlech, Oliver [Akademischer Betreuer] Kester, Holger [Gutachter] Podlech, and Oliver [Gutachter] Kester. "Development of a 108 MHz 4-Rod CW RFQ-design for high duty cycle acceleration of heavy ion beams at the GSI-HLI / Daniel Koser ; Gutachter: Holger Podlech, Oliver Kester ; Holger Podlech, Oliver Kester." Frankfurt am Main : Universitätsbibliothek Johann Christian Senckenberg, 2021. http://d-nb.info/1233479962/34.
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44
Neff, Stephan Hans. "Heavy-ion Beam Transport in Plasma Channels." Phd thesis, 2005. https://tuprints.ulb.tu-darmstadt.de/561/1/phd.pdf.
Повний текст джерелаАнотація:
Concepts for heavy-ion fusion (HIF) reactors require the transport of kiloampere ion beams over distances of several meters inside the reactor chamber. A possible solution for this task is to use assisted pinched transport (APT) for the final transport of the beam. This scheme uses an adiabatic plasma lens to focus the beam outside the chamber and a plasma channel to transport it inside the reactor chamber towards the fusion target at the center. The plasma channel has three functions: it neutralizes both the space charge and the current of the ion beam and furthermore creates a large azimuthal magnetic field that prevents the beam ions from leaving the channel. The appeal of the APT scheme is that it separates the focusing of the beam from the final transport, thus relaxing the focusing requirements of the beam. The purpose of this study is to demonstrate the creation of long, free-standing channels and to study their magnetohydrodynamical stability and their transport properties for low-current heavy-ion beams inside the channels. It is the result of a collaboration with Lawrence Berkeley National Laboratory and thus contributes to the ARIES fusion reactor study. In combination with the results of detailed transport simulations for high-current heavy-ion beams, which are part of the ARIES study, the results of the experiments make it possible to map out a set of suitable operating parameters for the channel transport of beams with reactor-like parameters, for instance the required discharge current and plasma density. Previous transport experiments at the Gesellschaft für Schwerionenforschung (GSI) used a discharge chamber that was 50 cm long and 60 cm in diameter. To get closer to reactor scales the chamber was extended by inserting a 50 cm long chamber section, resulting in a total length of 1 m. Since the prolongation changed the geometry of the chamber and thus the electric fields inside of it, it was necessary to optimize the fields by setting each section of the chamber to a separate potential. The electric setup was optimized with the help of detailed electrostatic calculations for the chamber. The channels are created in a three-step process. After the channel initiation, which guides the discharge along the chamber axis, a prepulse, that is a small discharge, heats the gas on the axis, resulting in a rarefaction and thereby stabilizing the subsequent main discharge. Two methods of channel initiation were used successfully. Laser-initiated channels were created in ammonia and ion-beam initiated channels in various other gases, such as krypton and xenon. The evolution of the channels is consistent with results from a one-dimensional MHD simulation. The channels are stable for normal operating conditions. A detailed study of channels in ammonia revealed that the channels become unstable for high gas densities, when the prepulse can no longer be used. The instabilities show the characteristics of kink instabilities, and their growth is consistent with the predictions of a simple analytical model. Proof-of-principle experiments demonstrate the transport of low-current heavy-ion beams. The transport properties of the channel were studied and found to be consistent with the assumption of a homogeneous current density in the channel, leading to betatron oscillations. In combination with the results of simulations for the transport of high-current beams and theoretical estimates about the growth of beam-plasma instabilities, the experimental results yield an estimate for a suitable set of operating parameters for assisted pinched transport in a fusion reactor.
45
Adonin, Aleksey [Verfasser]. "Heavy ion beam pumped KrF* excimer laser / von Aleksey Adonin." 2008. http://d-nb.info/988433826/34.
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46
"Conceptual design of heavy ion beam compression using a wedge." 2015. http://repository.lib.cuhk.edu.hk/en/item/cuhk-1291277.
Повний текст джерелаАнотація:
Wong, Chun Yan Jonathan = 以楔形靶壓縮重離子束的概念設計 / 黃駿仁.Thesis M.Phil. Chinese University of Hong Kong 2015.
Includes bibliographical references (leaves 140-144).
Abstracts also in Chinese.
Title from PDF title page (viewed on 15, September, 2016).
Wong, Chun Yan Jonathan = Yi xie xing ba ya suo zhong li zi shu de gai nian she ji / Huang Junren.
47
Sprouster, David John. "Ion beam formation and modification of Cobalt nanoparticles." Phd thesis, 2010. http://hdl.handle.net/1885/150492.
Повний текст джерелаАнотація:
This thesis has investigated the structural and vibrational properties of ion beam synthesized Co nanoparticles (NPs) and the influence of ion irradiation on the size, shape, crystallographic phase and structure. The evolution of the aforementioned properties were determined using a combination of laboratory and synchrotron based techniques, including cross-sectional transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS) and X-ray absorption spectroscopy (XAS). The results of this thesis have revealed a rich array of shape and structural transformations in Co NPs and highlights the effectiveness of a combined ion implantation/ion irradiation procedures in controlling and tuning the NP size, shape, crystallographic phase and structure. The structural and vibrational properties of Co NPs embedded in Si0{u2082}, formed by ion implantation were investigated as a function of the implantation concentration and post implantation annealing conditions. The implantation concentration and annealing temperature governed the spherical NP size and phase. X-ray absorption near-edge spectroscopy (XANES) was used to quantify the RCP, FCC and oxide fractions. The structural properties were characterized by extended X-ray absorption fine structure spectroscopy (EXAFS) and finite-size effects were readily apparent. With a decrease in NP size, an increase in structural disorder and a decrease in both the coordination number and bondlength were observed. The surface tension of Co NPs calculated using a liquid drop model was more than twice that of bulk material. The size-dependent vibrational properties were probed with temperature-dependent XAS measurements. Using a correlated anharmonic Einstein model and thermodynamic perturbation theory, Einstein temperatures for both NPs and bulk material were determined. Compared to bulk Co, the mean vibrational frequency of the smallest NPs was reduced as attributed to a greater influence of loosely-bonded, under-coordinated surface atoms relative to the effect of capillary pressure generated by surface curvature. Elemental Co NPs embedded in Si0{u2082} were irradiated with low energy Au ions and the evolution of the NP size and structure were then studied as a function of ion fluence. Upon irradiation, SAXS and TEM show that there was no change in the average NP size, in contrast to the short and long-range order where significant changes were observed. The coordination number decreased further while the mean value (bondlength), variance (Debye-Waller factor) and asymmetry (third cumulant) of the interatomic distance distribution all increased, as consistent with theoretical predictions for an amorphous elemental metal. Furthermore, the experimentally determined interatomic distance distribution for the irradiated Co NPs were in excellent agreement with molecular dynamics simulations for bulk amorphous Co and the observed structural changes were thus attributed to the formation of an amorphous phase. Such a crystalline-to-amorphous phase transformation is not readily achievable in bulk material (or large Co NPs) and the perturbed structural state prior to irradiation and the amorphous host matrix both contribute to nucleating and stabilising the amorphous phase in irradiated Co NPs. The Einstein temperature calculated from temperature-dependent XAS measurements for the unirradiated NPs showed a decrease in Einstein temperature. In contrast, that of the irradiated amorphous NPs was substantially higher than the bulk value. this apparent bond stiffening is attributed to the influence of the rigid surrounding matrix. When subjected to swift heavy ion irradiation, embedded FCC Co NPs were found to rapidly transform at low fluence to the HCP phase prior to any changes in size or shape. The crystallographic phase was identified with XAS and electron diffraction and quantified, as functions of the irradiation energy and fluence, with the former. The transformation was complete at low fluence and was governed by the electronic-energy-loss of the incident ions. A direct-impact mechanism was identified with the transformation interaction cross-section correlated with that of a molten ion track in amorphous Si0{u2082}. The swift heavy-ion irradiation-induced phase transformation was attributed to the large shear stress resulting from the rapid thermal expansion about an ion track in the Si0{u2082}. The size, shape and structural evolution of embedded Co NPs subject to high fluence swift heavy ion irradiation were also investigated over a wide energy region. Various electronic-energy-loss-dependent shape and structural changes in the Co NPs were observed. Depending on the irradiation energy, NPs below 4-7 nm remained spherical in shape and progressively decreased in size with fluence due to dissolution. NPs with sizes above a threshold diameter readily transformed into ellipsoids with their major dimension parallel to the incident ion beam direction. Modifications of the atomic-scale structure were characterised with XAS. Prior to irradiation, all Co atoms were in a metallic state. After SHIl, however, Co atoms were found in different atomic environments including: large elongated NPs, small spherical NPs and a large fraction of isolated Co atoms bonded to O in the matrix. The work presented in this thesis has resulted in the identification and understanding of a number of fundamental and technologically important effects in the formation and irradiation of Co NPs embedded in a Si0{u2082} matrix. Results demonstrate that the the size, shape and structure of Co NPs formed by ion implantation and thermal annealing in Si0{u2082} can be readily controlled by ion irradiation. This methodology represents an effective means of controlling the NP properties to best suit specific technological applications.
48
Kupka, Katharina. "Intense heavy ion beam-induced effects in carbon-based stripper foils." Phd thesis, 2016. https://tuprints.ulb.tu-darmstadt.de/5611/1/Dissertation_KatharinaKupka.pdf.
Повний текст джерелаАнотація:
Amorphous carbon or carbon-based stripper foils are commonly applied in accelerator technology for electron
stripping of ions. At the planned facility for antiproton and ion research (FAIR) at the Helmholtzzentrum für
Schwerionenforschung (GSI), Darmstadt, thin carbon stripper foils provide an option for directly delivering ions
of intermediate charge states to the heavy ion synchrotron, SIS 18, in order to mitigate space charge limitations
during high-intensity operation. In case of desired high end-energies in the synchrotron, a second stripping process
by a thicker carbon foil provides ions of higher charge states for injection into the SIS18. High beam intensities and
a pulsed beam structure as foreseen at FAIR pose new challenges to the stripper foils which experience enhanced
degradation by radiation damage, thermal effects, and stress waves. In order to ensure reliable accelerator operation,
radiation-hard stripper foils are required. This thesis aims to a better understanding of processes leading to
degradation of carbon-based thin foils. Special focus is placed on ion-beam induced structure and physical property
changes and on the influence of different beam parameters.
Irradiation experiments were performed at the M3-beamline of the universal linear accelerator (UNILAC) at GSI,
using swift heavy ion beams with different pulse lengths and repetition rates. Tested carbon foils were standard
amorphous carbon stripper foils produced by the GSI target laboratory, as well as commercial amorphous and
diamond-like carbon foils and buckypaper foils.
Microstructural changes were investigated with various methods such as optical microscopy, scanning electron microscopy
(SEM), profilometry and chromatic aberration measurements. For the investigation of structural changes
X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, high resolution transmission electron microscopy
(HRTEM), in-situ Fourier-transform infrared spectroscopy (FTIR) and small angle X-ray scattering (SAXS) were
used. The changes of physical properties, in particular the electrical resistivity, thermal conductivity and stiffness
of the foils were studied by in-situ 4-point probe, laser flash analysis and atomic force microscopy, respectively. A
technique for measuring temperature of very thin, semitransparent and free-standing stripper foils during irradiation
by means of an infrared (IR) camera was developed and applied.
The experimental investigations were complemented by molecular dynamics simulations of amorphous carbon exposed
to different swift heavy ions. The simulations provide information on the structural changes in the tracks at
atomic scale. Virtual amorphous carbon cells were created by simulating liquid quenching and plasma deposition,
yielding cells with different degrees of clustering of sp2 and sp3 bonding. The impacts of swift heavy ions were
modeled by an instantaneous energy deposition deduced from inelastic thermal spike model calculations.
Results of experiments and simulations provide evidence for the beam-induced transformation of amorphous carbon
to a defected graphitic structure and for clustering of sp2 and sp3 bonds. These structural changes result in
severe property changes. The electrical and thermal properties of amorphous carbon seem to improve during beam
exposure, but the mechanical properties degrade severely. The beam conditions have a strong influence on the
evolution of induced structure and property changes.
A better understanding of the response of (amorphous) carbon stripper foils to swift heavy ion beams as revealed by
dedicated irradiation and characterization experiments performed within this thesis, provides criteria for material
requirements for future stripper foils used in high-power heavy ion accelerators such as FAIR.
49
Imran, Muhammad. "Study of Heavy Ion Beam Interaction with High Energy Laser Produced Plasmas." Phd thesis, 2011. http://tuprints.ulb.tu-darmstadt.de/2696/1/Muhammad_Imran_Doktorarbeit.pdf.
Повний текст джерелаАнотація:
Cryogenic solid-state targets of rare gases as well as nitrogen and deuterium have been developed for the measurements of the energy loss of heavy ions in dense, laser produced plasmas. Free-standing targets with a thickness of 1 cm to 1 mm and planar foil-supported targets with a thickness of few hundred of microns have been produced using interchangeable, remotely controlled target growing chambers. The geometry of the targets is determined by the geometry of the growing chamber. In addition to this, work has been contributed to the
construction of the portable cryogenic system used for growing the rare gas, nitrogen and deuterium crystals.
The first laser plasma experiments were performed by irradiating free standing cubic nitrogen targets with the nhelix laser. Interferometric measurements revealed the electron density of the order of 10^{19} cm^-3. Additional experiments have been performed with thin foil-supported deuterium targets. The target foil was irradiated from both sides using the nhelix and PHELIX laser systems while the ion beam from UNILAC was used to study the interaction. The electron density values obtained for deuterium plasmas are similar to those for nitrogen plasmas. The outcome of these experiments paves the way to realize beam-plasma interaction experiments at Z6, employing cryogenic targets.
The projectiles of an ion beam transfer momentum and energy to the target particles by Coulomb interactions. The energy loss of the projectiles is therefore also dependent on the ionization energy of the targets. In plasmas the ionization energy of the target particles is determined by its temperature and density. With increasing plasma temperatures and pressures, one obtains a lowering of the ionization energy. This fact has already been established by several authors, however up to now the resulting approximations were too rough. Thus in the present work it is attempted to contribute to a more careful recalculation of the lowering of the ionization energy of dense hydrogen-like bound states.
For this purpose the Jacobi-Pade approximation of relative energy level shifts is applied. There the relative energy level shift of the five-fold ionized carbon is determined by the difference between Coulomb and Debye potential and by the kinetic energy of the particles. The shift caused by the kinetic energy has to be found considering the momentum space of the particles, so that nine-fold integrals in phase space have to be calculated. Quantum physically, former numerical calculations for the energy shift were only performed for particle states with zero angular momentum quantum numbers. Presently, a detailed, to a large extent analytical analysis of the shift caused by kinetic energy is given for any angular momentum quantum number enabling also an improved analysis of in future developed Jacobi-Pade formulae. The relative energy shifts of the bound-states of the five-fold ionized carbon are numerically obtained as function of the Mott parameter of the plasma. Dependencies of the shifts on main quantum numbers and orbital angular momentum quantum numbers are also discussed.
50
Grieser, Jochen Michael. "Beam Phase Feedback in a Heavy-Ion Synchrotron with Dual-Harmonic Cavity System." Phd thesis, 2015. https://tuprints.ulb.tu-darmstadt.de/4634/1/Dissertation.pdf.
Повний текст джерелаАнотація:
This dissertation contributes to the design and analysis of bunch phase feedback systems in a heavy-ion synchrotron which is operated with a dual-harmonic cavity system.
Due to the ring structure of the synchrotron the particles are focused in transverse and longitudinal direction forming particle bunches, which may be subject to various disturbances. Depending on the disturbance, bunch oscillations may occur, which lower the beam quality and may also lead to particle loss. This compromises the efforts which are constantly taken to increase the beam intensity, energy and quality. Thus, control measures are taken to stabilize the beam, which are usually based on the linearized single particle dynamics. In the present case, however, the accelerating voltage is supplied by two cavities running with different frequencies, introducing an additional nonlinearity, and simple linearization of the voltage is no longer possible.
The problem of modeling and damping of rigid dipole oscillations in case of a dual-harmonic cavity system is treated here by deriving a simple linear model based on central moments, which is accurate enough to serve as a base for various control design approaches. Beside the feedback already existing at GSI Helmholtzzentrum für Schwerionenforschung GmbH for single-harmonic operation based on a finite impulse response filter, which is transferred here to the dual-harmonic case, an alternative filter design for the feedback is presented, along with different output controllers based on pole placement and a state feedback combined with an observer.
The effectiveness of the feedback with a finite impulse response filter was demonstrated in two beam experiments, which are also presented in this dissertation.