The atoms of a molecule are always restless and are constantly moving in one way or another.Apart from rotations and translations, they may vibrate in many different modes. They may moveradially toward or from each other, so called stretching. This can be done symmetrically or asymmetrically.The angels between a pair of atoms may change seen from a common atom, so calledbending. This may be done in a common plane like scissoring or rocking, or out of plane like waggingor twisting.Anyhow, it is of interest to study these movements — since they work as a fingerprint of themolecule. Two methods for studying these behavior are Raman- and IR-spectroscopy. Some vibrations,such as symmetric stretching, are mainly seen using Raman spectroscopy (Raman active); whilebending and asymmetric stretching are primarily detected by IR spectroscopy (IR active) However,all types of combinations exist, so there are no watertight compartments between them. Instead, themethods are complementary to each other.In this article, I build up a semi-classical model of the vibrations for the case of IR-spectroscopy,and implement it in Mathematica to test the model. It is based on classical physics such as vibratingspringmechanics and Maxwell’s electrodynamics, but the vibrations are computed using modernphysics quantum mechanics. Since there are several atoms involved (say N) and the vibrations betweenthese atoms are in 3 dimensions, this may be described by 3N coupled 1-dimensional harmonicoscillators. By suitable transformations these oscillators are uncoupled, but results in a wave functionwhich is the product of 3N eigenfunctions, one for each oscillator’s eigenfunction of a given mode.Adding a time varying electric field (the IR-illumination), we need the time dependent SchrödingerEquation, where the potential is time varying sinusoidally. Necessary perturbation theory for suchtime dependency is described in some details, and an expression for the dipole moment needed forthe estimation of the IR absorption by the molecule is given. However, the model also depend onthe electrons’ orbitals and the total bond energy within the molecule. These are given by a DFT(Density Functional Theory) computer code, which serve as input to my calculations.The standard approach to do IR-spectrum calculations is to use DFT also to move the atoms inthe directions of the vibrations and compute how the dipole moments for the molecules change. Mymethod is instead to use SE directly for the many vibrating particle problem based on the knownexact solutions to the one dimensional harmonic oscillator. This is followed by perturbation theoryfor the time dependency of the IR-field to get the dipole moments.The drawback with my approach is that the electron clouds around the atoms are not affectedat all by the vibrations, they just follow the nuclei. The DFT approach takes care of the changingelectron density functions. However, my approach solves the vibrational problem more directly withthe SE and takes care of the time dependent potential using perturbation theory.Computational results for seven molecules containing between 2 and 11 atoms are shown andcompared with spectroscopic parameters and measurements compiled by established references. Theconclusion is that my model and computational output are well in accordance with these references,and some shortcomings and possible enhancements are pointed out. The drawback with the electronclouds might affect the absorption levels of the vibrations rather than their energies and are possiblein future work to take into account. / <p>Till minne av Ulf Oreborn (1957-2018)</p>

Kolliderare är en typ av partikelaccelerator som används till att kollidera subatomiska partiklar och är viktiga för utförandet av experiment i partikel- och kärnfysik. Laddade partiklar accelereras och hålls i separata omloppsbanor med dipol- och kvadrupolmagneter, och deras banor korsar varandra minst en gång. De laddade partiklar som åker i en omloppsbana kan generaliseras till en laddad partikelstråle. Dessa strålar propagerar åt motsatta håll, och när dessa kolliderar rakt in i varandra, är laddningarna så tätt fördelade att dess elektriska fält påverkar partiklarna i den motgående strålen. Denna så kallade beam-beam effekt begränsar prestandan på kolliderare, och det är därför av intresse att kunna beskriva denna effekt med en såprecis modell som möjligt. I denna rapport testas en modell av beam-beam effekten som baserar sig på en modell som beskrevs av M. A. Furman, K. Y. Ng och A. W. Chao i rapporten "A Symplectic Model of Coherent Beam-Beam Quadrupole Modes"från 1988, men med en ändring på hur de elektriska fälten påverkar de laddade partiklarna. Denna modell testas därefter mot Furmans modell, och den nya modellen utvärderas. Den nya modellen ger stabilare strålningsspridningar under inverkan av beam-beam effekten jämfört med Furmans modell.

Non-linear errors in the magnetic field of the Large Hadron Collider (LHC) at CERN often lead to undesirable resonances and instabilities in the particle motion, which can negatively affect the operations of the accelerator. This project focuses on developing a new correction scheme with a response matrix approach to optimize the values of the skew sextupolar correctors of the LHC at injection, in order to mitigate the impact of resonance driving terms (RDTs). So far, no correction has been introduced to actively compensate these RDTs. In particular, we investigate the RDTs related to the 3Qy resonance, which has been proposed to be connected to emittance growth in the LHC, leading to a loss of luminosity in the detectors. Starting from a basic linear model of the LHC, we gradually introduce more complex errors and demonstrate that this correction scheme is more effective than the standard correction. The correction scheme also proves to be effective for more advanced non-linear models, also considering alignment errors.

No description available.

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 &lt; δ &lt; 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.

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.