In many optics applications we need lenses with dynamically tunable focal lengths. One design of such a lensis developed in and it relies on the magneto-optical eect. In this design, a graphene layer is placed ina magnetic eld that varies quadratically in space. During this project I have built an experimental set-upthat can be used to make magneto-optical measurements. The graphene sample is placed in an evacuatedcryostat and it needs to be cooled to low temperatures using liquid nitrogen. The magnetic eld neededfor the measurements is generated by a permanent magnet system placed outside the cryostat. This reportpresents the theory behind the optical magnetic lens, a description of the cryostat and of the steps I tookto design and build the cooling system and the magnet system. Finally, temperature and magnetic eldmeasurements are presented and compared with the values obtained from COMSOL simulations.

In this work, we have studied the photochromic response of several oxygen containing rare-earth hydride thin films (REHO, RE = Y, Nd, Gd, and Dy). Their chemical composition was characterized by an iterative multi-method approach based on ion beams, while the photochromic effect was measured by means of optical spectrometry. We report photochromic responses for YHO, NdHO, GdHO and DyHO of several thicknesses but averaged chemical compositions described by the formula REH2-δOδ; in the range of 0.45 < δ < 1.5 (δ being the [O]/[RE] ratio). Possible side-effects of the ambient conditions on the photochromic effect in YHO thin films were investigated by comparing the optical properties (photochromic response and bleaching) of YHO films capped with two different diffusion barrier layers (Al2O3 and Si3N4) to their respective uncapped sample. The ambient atmosphere was found to play no significant role in the photochromic effect. In sequence, identical YHO thin films were prepared on three different (transparent) substrates (i.e., soda lime glass, CaF2, and Al2O3 as buffer layer). The effect of substrate induced stress in the YHO thin films was investigated in details and no significant correlation between the substrate and photochromic effect was observed. Finally, isotope labeling in double layers of YHO and YDO was done to investigate possible diffusion of hydrogen/deuterium within the REHO layers. No diffusion of hydrogen/deuterium could be observed in the double layered structure during a one-week period and one illumination/bleaching cycle.

Includes bibliographies. / The effect of a 0,2 μm air venting in-line filter on the incidence of post-infusion phlebitis was studied in a prospective, controlled, observer-blind investigation of 132 infusions. The filters were changed daily and the infusions were allowed to continue until no longer required, or until there was a reason for discontinuation. Microbiological evaluation of filters, skin at the site of cannulation immediately prior to removal of cannulae, and cannula tips was performed. Particle size analyses of the commonly used intravenous infusion fluids and medicines was also carried out. The incidence of phlebitis was significantly reduced by the inclusion of the filter in-line. The efficacy of the filter in reducing phlebitis was most pronounced when intravenous antimicrobial agents, especially the cephalosporins, were administered. Micro-organisms were isolated from 13% (28/209) of filters which originated from 31% (16/32) of infusions with filters in-line. A relationship could not be established between the number of filters used per infusion or the number of intravenous additives to the infusion system. Phlebitis was not associated with microbial contamination of cannula tips. Medicines for intravenous administration, especially the powders to be reconstituted prior to administration, were heavily contaminated with particulate matter prior to filtration.

Replacement of the superconducting magnet used in the SPECTRAP laser spectroscopy experiment at GSI necessitates redesign of some associated components. This thesis investigates a potential new beamline for SPECTRAP using a single pulse drift tube to slow the ions down. The beamline contains three parts, a horizontal part connected to the low-energy HITRAP beamline, a vertical part which transports the ions to the pulse drift tube and the pulse drift tube itself.   Simulation and tuning of the horizontal beamline were performed using the ion optics code called COSY Infinity. The resultant beam was then continued into the vertical part in SIMION. The components were then tuned by hand. The result was approximately 19% of ions ending up within the radius of the input beam used when simulating the pulse drift tube.   Additionally, the function of a crown-shaped pulse drift tube were analysed, consisting of two interlocked serrated tubes separated by a small distance. Simulations were performed in SIMION based on reasonable input beam conditions. The effect of parameters influencing the behaviour of the ions traversing the pulse drift tube were investigated, leading to optimisation of operating voltages and design specifications.   Based on the results of the simulations performed it was determined that a beamline based on a single crown-shaped PDT could be feasible. It is however unclear if existing beamline components could operate at the voltages required for transport to the pulse drift tube.

With help from a 3D-camera Photon Sports has developed reliable and easy-to-use technology tomeasure and give feedback to athletes during performance tests. This technology makes it possibleto directly extract a number of parameters Key Performance Indicators (KPIs).In most field sports, multidirectional acceleration and deceleration are key areas to improveto become quicker as an athlete. However, it has become clear that only using the 3D-camera hassome limitations. This project aims to investigate if accelerometers can provide us with this extrainformation and thereby complement measurement technology to the measurements PhotonSports are doing today.We have done a three-part project where we first focused on time synchronization betweenclocks from the 3D-camera and the accelerometers. In the second part, we investigated how wellwe can extract the ground contact time (gct) during sprint using accelerometers attached to thefeet of the athlete. In the third and last part, we studied how we can combine both the 3D-cameraand the accelerometers to extract new KPIs that we were unable to extract before.From our developed time-synchronization algorithm, we found that the result is promisingif one looks at how the measured acceleration data from both devices are matching each othervisualy, however, it does not agree with the reference data we have extracted using a Software-Development-Kit (SDK) and Photon Sports already developed application. The gct was evaluatedto values in most cases either ranging between 100 ms and 200 ms or 300 ms and 400 ms. Whencomparing to earlier studies it seems like gct in the 100−200 ms interval are closer to the correctvalue whilst there has been some error in the calculations in the later interval. By combiningthe camera and the accelerometers we were able to extract leg stiffness and reactivity index as newKPIs. The KPIswere evaluated to a reasonable value, however, it became apparent both fromcalculationsof the newKPIs and the gct that the lowsampling rate of the camera and the accelerometersare an obstacle to reliably compute these parameters. We could therefor conclude that if PhotonSports want to introduce new tests where accelerometers are used they should be aware of the limitationsthat comes with i low sampling rate and be sure they try to compute KPIs that are possibleto evaluate with the sampling rate they have.

No description available.

The work in this thesis covers the design, growth and characterisation of neutron multilayers. The performance of these multilayers is highly dependent on the obtained interface width between the layers, even a modest improvement can offer a substantial increase in reflectivity performance. As multilayers are such an integral component of many neutron optical instruments, any improvement in terms of reflectivity performance has broad implications for all neutron scattering experiments. This project has been carried out with the construction of the European Spallation Source (ESS) in mind, but the principles extend to all neutron scattering sources. Ni/Ti is the conventional material system of choice for neutron optical components due to the high contrast in scattering length density (SLD). The reflected intensity of such components is largely dependent on the interface width, caused by the formation of nanocrystallites, interdiffusion, and/or intermixing. Apart from hampering the reflectivity performance, the finite interface width between the layers also limits the minimum usable layer thickness in the mirror stack. The formation of nanocrystallites has been eliminated by co-depositing of B4C . This has been combined with a modulated ion assistance scheme to smoothen the interfaces. X-ray reflectivity (XRR) measurements show significantly improvements compared to pure Ni/Ti multilayers. This has further been investigated using low neutron-absorbing 11B4C instead. After deposition, the 11B4C containing films have been characterized using neutron reflectometry, X-ray reflectivity, transmission electron microscopy, elastic recoil detection analysis, X-ray photoelectron spectroscopy. A large part of his work has focused on fitting X-ray and neutron reflectivity measurements in order to obtain structural parameters. The fits to the experimental data suggest a significant improvement in interface width for the samples that have been co-deposited with 11B4C using a modulated ion assistance scheme during deposition. Any accumulation of roughness has been eliminated, and the average initial interface width at the first bilayer has been reduced from 6.3 Å to 4.5 Å per bilayer. The respective reflectivity performance for these structural parameters have been simulated for a neutron supermirror (N = 5000) for both materials at a neutron wavelength at λ = 3 Å using the IMD software. The predicted reflectivity performance for the 11B4C containing samples amounts to about 71%, which is a significant increase compared to the pure Ni/Ti samples which have a predicted reflectivity of 62%. This results in a reflectivity increase from 0.84% to 3.3% after a total of 10 reflections, resulting in more than 400% higher neutron flux at experiment.

Despite advancements in device design and anti-coagulation treatments, there are numerous adverse events that may occur following implantation of LVADs. The most devastating involves the embolization of thrombus into the brain causing a stroke, with incidence of up to 14-47% over a 6–12-month period. This study aims to elucidate ways to reduce this risk by surgical maneuvers guided by a multi-scale computational fluid dynamics analysis wrapped around a multi-objective shape optimization scheme which optimizes the anastomosis location of the VAD outflow graft (OG) along the ascending aorta to minimize the incidence of thrombi reaching the cerebral vessels and reduce particle residence times. The computational model comprises of two coupled parts: a 50 degree of freedom 0-D lumped parameter model of the peripheral circulation that is loosely-coupled to a 3-D CFD model of the aortic circulation. Blood flow is modeled as laminar, incompressible and the non-Newtonian blood rheology is accounted for by the Carreau-Yasuda model. A Lagrangian particle tracking scheme is used to model thrombi as non-interacting particles. The results verify the hypothesis that a surgical maneuver that tailors the LVAD-OG anastomosis configuration can minimize the incidence of cerebral embolization. This is exemplified most in the case that considered particle release from the OG, as a fivefold decrease in cerebral embolization resulted from optimizing the implantation configuration. It was found that shallow orientations are most optimal in minimizing the cerebral embolization in the case where particles originate from the aortic root walls and the ventricle. In the last case, where particles were released from all three origins, the optimal implantations show a proclivity for intermediate implementations that direct the momentum of the VAD-jet towards the lumen of the aortic arch. Discrete coefficient of restitution sensitivity analysis reveals a negligible effect on cerebral embolization incidence as particle-wall collisions become less elastic.

High electrical fields are needed inside the accelerating cavities of particle accelerators in order to accelerate the particles to higher energies in shorter distances. But high electrical fields will lead to electrical breakdowns. The electrical breakdowns are events in which the insulating proprieties of a typically electrically insulating medium are weakened due to the presence of high electrical fields. One of the best insulating mediums is the ultra high vacuum because there are no molecules that will ionize and that will conduct the electricity. But even in vacuum, there will be electrical breakdowns. They are called vacuum arc breakdowns. The conducting medium in this case is given by the ions and the electrons emitted from the metal surface of the electrodes that create the high electrical fields.  It has been observed that applying repeatedly high electrical fields on the surface of the electrodes reduces the number of breakdowns. This process is called conditioning. One explanation is that the large electric fields create dislocations near the surface of the metal that reduce the probability of having new vacuum arc breakdowns. These dislocations should also increase the electrical resistivity of the metal near its surface. To test if new dislocations are formed during conditioning, precise measurements of the surface resistivity are needed. These measurements will be made with radio pulses in the GHz range. In this range of frequencies, the electromagnetic fields penetrate only a few microns inside the surface of the metal and it will be possible to measure only the resistivity of the metal near its surface. The surface resistivity data is encoded in the quality factor (Q-factor) of a resonant cavity. This parameter describes how fast the energy is dissipated inside the cavity. A larger surface resistivity leads to a larger dissipation of energy in the walls of the cavity and to a lower Q-factor. It is advantageous to perform the measurements in cryogenic conditions because the increase in resistivity due to the formation of dislocations is much more pronounced at very low temperatures. The measurements are planned for the discharge system available in FREIA laboratory, that consists of two electrodes, separated by a small gap (60 µm), and placed inside a cryostat cooled with liquid helium. In this thesis, I describe the algorithms used to extract the Q-factor from experimental data and the results of some experiments done using the electrodes and test cavities. Small changes in resistivity (less than 0.6%), induced by temperature changes, were measured. The final chapter explores the results of the 3D EM simulations, where the electrode system in the cryogenic setup in FREIA laboratory is modified to act as a resonant cavity.

Att få en fördjupad bild av energiförlusten när joner med olika initialenergier interagerar med diverse material kan lägga grunden till viktig forskning inom till exempel materialvetenskap och strålbehandling. Det här projektet gick ut på att utföra flygtidsmätningar för att bestämma energiförlust för accelererade jod och vanadinjoner med energier mellan 4 och 44 MeV vid passage genom tunna fristående filmer av aluminium och titan. För att framställa tunna filmer sputtras material på en saltbelagd glasskiva som därefter sänks ner i vatten så saltet löses upp och filmen kan fiskas upp på en hållare. I en accelerator bombarderas folierna med joner och flygtiden mäts i en flygtidsdetektor. Skillnaden mellan de flygtider som mätts med och utan en folie kan sedan kalibreras om till energiförlust. Vid analys av filmernas tjocklek visade sig, framförallt för titanfilmerna, föroreningar och ojämnheter bidra till felkällor och påverka resultatet. Resultatet följer tidigare forskning väl vilket ger metoden merit men med vissa avvikelser som antas bero på felanpassad mätdata.