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.

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.

<p>Presentation held over Zoom.</p>

Tanken med detta arbete var att analysera låtar av Bruce Springsteen för att bli bättre på att arrangera musik som honom. För att göra detta valde jag ut 23 av hans låtar och analyserade dem utifrån fem olika arrangeringselement hämtade ur boken The Mixing Engineer's Handbook. Resultatet blev att jag lärde mig mycket om hur man kan arrangera rockmusik och nya sätt att använda instrument. Dock skulle man nog behöva gräva betydligt djupare ner i låtarna för att få ut det där riktiga guldet som är kännetecknet för Bruce Springsteen &amp; The E-Street Band.

I det här projektet undersöks vad resultatet blir när melodier ur egenskriven populärmusik orkestreras och arrangeras för symfoniorkester i den klassiska formen av rondo, i detta fall efter en äldre form av rondo bestående av fyra återkommande teman samt tre episoder eller avvikelser från temat. Denna typ av rondo var populär under barocken och romantiken. Målet var att ta reda på om jag med begränsade förkunskaper inom den klassiska konstmusiken kan skapa ett stycke musik som påminner om ett utdrag ur en symfoni från 1800-talets romantik men där sagda stycke baseras på bandet Kainoabels melodier. För att uppnå detta har jag valt att skriva efter en form och för ett instrumentarium som ofta representeras inom den klassiska konstmusiken samt att jag efter bästa förmåga tar inspiration från delar ur en symfoni skriven av Johannes Brahms år 1883. Även andra stycken, som har valts ut i samråd med handledare, har agerat inspirationskälla under projekttiden. Resultatet visar på att det nyskrivna stycket klingar mer nutida än önskat på grund av melodiernas ofta joniska karaktär. Stycket fick i min mening andra stildrag än vad som önskades i målsättningen men som ändå innehar andra kvaliteter som kan beskrivas som mer filmiska och stundtals juvenila. / This project investigate what the outcome is when melodies from self-produced popular music are orchestrated and arranged for symphony orchestra in a form of rondo. In this case, after an older form of rondo consisting of four recurring themes as well as three episodes or deviations from said theme. This kind of rondo was made popular during the baroque and romantic epoch. The goal is to find out if, with limited previous knowledge in the field of classical art music, I can create a piece of music that reminds of an excerpt from a symphony from the 19th century romanticism where the said piece is based on melodies of the band Kainoabel. In order to achieve this, I have chosen to write after a form and an instrumentarium that is often represented in classical art music and that I take inspiration from parts of a symphony written by Johannes Brahms in 1883. Other pieces of music, selected in consultation with a supervisor, have acted as inspirational sources during the project. The result show that the newly written piece sounds more contemporary than desired due to the often ionic character of the tunes. In my opinion, the piece got a different character than desired but still possesses other qualities that can be described as more cinematic and sometimes juvenile.

The thermodynamics inside the helium liquefier in the FREIA laboratory still contains many unknowns. The purpose of this project is to develop a theoretical model and implement it in MATLAB, with the help of the CoolProp library. This theoretical model of the FREIA liquefaction cycle aims at finding the unknown parameters not specified in the manual of the manufacturer, starting from the principle of enthalpy conservation. Inspiration was taken from the classical liquefaction cycles of Linde-Hampson, Claude and Collins. We developed a linear mathematical model for cycle components such as turboexpanders and heat exchangers, and a non-linear model for the liquefaction in the phase separator. Liquefaction yields of 10% and 6% were obtained in our model simulations, with and without liquid nitrogen pre-cooling respectively - similar to those in the FREIA liqueuefier within one percentage point. The sensors placed in FREIA showed similar pressure and temperature values, even though not every point could be verified due to the lack of sensors. We observed an increase of more than 50% in yield after adjustments of the heat exchanger design in the model, especially the first one. This constitutes a guideline for possible future improvements of the liquefier. / Termodynamiken bakom heliumförvätskaren i FREIA-laboratoriet innehåller fortfarande många okända aspekter. Detta kandidatarbete syftar till att utveckla en teoretisk modell och implementera den i MATLAB med hjälp av biblioteket CoolProp. Denna modell av FREIA:s förvätskningscykel syftar till att hitta de okända parametrar som inte specificerats av tillverkaren, och baserar sig på principen om entalpins bevarande. Inspiration togs från de klassiska förvätskningscyklerna Linde-Hampson, Claude och Collins. Vi utvecklade en linjär matematisk modell för cykelkomponenter såsom expansionsturbiner och värmeväxlare, och en icke-linjär modell för själva förvätskningen i fasseparatorn. En förvätskningsverkningsgrad på 10% och 6% uppnåddes i våra modellsimuleringar, med respektive utan förkylning med flytande kväve - liknande verkningsgraderna i FREIA- förvätskaren inom en procentenhet. Sensorerna placerade i FREIA visade på liknande tryck och temperaturer, även om bristen på sensorer gjorde att vi inte kunde bekräfta varje punkt. Vi observerade en ökning på mer än 50% i verkningsgrad efter att ha justerat värmeväxlardesignen något, speciellt för den första. Detta kan utgöra riktlinjer för var man framöver kan förbättra den faktiska förvätskaren. / <p>Subject reader/Ämnesgranskare: Roger Ruber</p>

Fourier filtering is a powerful technique to improve the contrast when imaging through turbid media. However, the trade-off between contrast and spatial resolution is a long-standing issue that limits the Fourier filtering technique to low spatial resolution requirements. This report circumvents this trade-off by combining several high contrast but low spatial resolution images into one high spatial resolution, high contrast image using a phase retrieval algorithm. The high contrast, low resolution images were obtained in two methods; rotating an asymmetric Fourier filter and translating a symmetric pinhole filter across the Fourier domain. The former approach, when combined with the phase retrieval algorithm, successfully constructed a high spatial resolution, high contrast image through an optical density of OD = 13.7. The problem with this technique is its temporal sluggishness as several images need to be captured and then processed to form one high resolution image making it difficult to use for fast moving object e.g. Combustion sprays. Here, I propose a new technique called Phase Retrieval Algorithm for Multiple Exposures (PhRAME) which is an instantaneous method to capture all the required images for the phase retrieval algorithm by utilising an ultra-fast imaging technique called Frequency Recognition Algorithm for Multiple Exposures (FRAME). FRAME captures several images in one exposure allowing different spatial frequencies to be captured with the same high contrast in each image. These images are then combined via the phase retrieval algorithm into one high contrast, high spatial resolution image. While this report doesn't demonstrate the working of PhRAME, it demonstrates an intermediately step, that FRAME and the phase retrieval algorithm work in tandem.

ESS neutrino Super Beam (ESSnuSB) is a project that aim to create ahigh energy beam of neutrinos and anti-neutrinos to study thephenomenon neutrino oscillation and learn more about symmetryviolations in quantum mechanics. To create the neutrino beam, negativeHydrogen ions must be transported from the ESS linear accelerator at2.5 GeV, to a proton accumulation ring. This is done through a transferline, that shall direct the ion beam while preserve the beam as much aspossible. In thisproject, there was an attempt at finding a design for this transferline. Preferably, the line consists of a long main line of FODO cellsand two matching sections at each end. A simulation of the beam wasdone that gives the progression beta and dispersion functions,statistical measurements of the particle distribution, through a partof the transfer line. A design for the main line was found. For tuningthe quadrupole magnets, an iterative method using the system's responsematrix was used. However, it could not match more than four parametersat the time, while six was required for complete matching. Because ofthis, it is not able to match thedispersion.

This thesis discusses the design, construction and testing of a highefficiency, 100 MHz, 1 kW, Class-E solid state power amplifier. The design was performed with the aid of computer simulations using electronic design software (ADS). The amplifier was constructed around Ampleon's BLF188XR LDMOS transistor in a single ended design. The results for 100 MHz operation show a power added efficiency of 82% at 1200 W pulsed power output. For operation at 102 MHz results show a power added efficiency of 86% at 1050 W pulsed power output. Measurements of the drain- and gate voltage waveforms provide validation of Class-E operation.