In this project, different fission models in the nuclear reaction code TALYS have been compared to GEF version 2020/1.2. The data included in the comparison are mass yield distributions, average prompt neutron energies per fragment mass, and average multiplicities of both neutrons and γ-rays per fragment mass. The reaction studied in the first part of the project is 1 keV neutron-induced fission of 235U. In the second part of the study, a variety of different nuclei and different incident energies were included in comparisons, but a limitation was set to only include neutron-induced fission. The results from the comparison suggested that TALYS fymodel 2 and 3 were less consistent with GEF than fymodel 4. For the comparisons with experimental data, fymodel 4 also performed better overall. TALYS fymodel 2 and 3 make use of implemented partial versions of GEF to produce fission fragment distributions, while fymodel 4 takes fission fragment distribution data from separate yieldfiles. A database of these yieldfiles with 737 different nuclei and 10 energy levels was produced, to be implemented in future versions of TALYS. The energy levels were chosen to get a range of energies that can be accurately interpolated between. This method of using TALYS fymodel 4 with a yieldfile from GEF consistently showed a strong agreement with GEF version 2020/1.2 for the mass yield distributions and the neutron multiplicities. The γ-ray multiplicities and the neutron energies show a slightly weaker agreement, and TALYS gives consistently smaller values than GEF for these quantities.

The presented project explores the current theoretical and experimental tools available within the study group for the Future Circular Collider (FCC) with focus on the electron-positron collider. The aim of the study is to evaluate the current frameworks used for simulation, and investigate the possibility of simulating long-lived particles, that could be dark matter candidates, through them. Pythia cards were run through the framework of Delphes and several different software packages were studied on the journey through the work. It was found that the current framework reconstructs the masses of a Z bosons and Higgs bosons accurately from the ZH signal, which is central for the analysis at the FCC-ee. When the same analysis was applied for the new physics case of a dark matter particle included in the new card for study, a ROOT file was produced indicating that the framework was able to handle the new case. When this card was run through the analysis software however, difficulties arose and a final output could not be achieved. Conclusively, it can be said that the current framework has the possibilities of handling new physics cases but further study is required to be able to run certain software packages on these cases.

Even though there is a multitude of observational evidence from cosmology and astrophysics, the standard model does not include a suitable dark matter candidate and therefore physics beyond the standard model is necessary. There are hypotheses of what the particle candidate could be coming from theories such as supersymmetry or extra dimensions. The processes producing these particles are understood very well from the theoretical perspective. The problem is that these processes have not been observed in any detectors. Therefore the nature of the dark matter remains unknown. However, it is clear that the dark matter-particle interacts with ordinary matter through gravity and in general, candidates may also interact through the weak force. These candidates are called Weakly Interacting Massive Particles. Therefore, by studying weak processes (weak in the sense that the processes are interactions mediated by a force weaker than the Electro-Magnetic and Quantum-Chromo dynamical-forces, not necessarily the weak force of the standard model) in the large hadron collider it may be possible to pose constraints on the dark matter signatures. One possible process which specifically involves the standard model electroweak interaction, which will be the model for the project, is the emission of scalar dark matter particles from the Z boson,which would result in a final state characterized by a Z boson and missing transverse energy. Simulations of the model and calculations of the cross section are done for different masses, ranging from 20−680 GeV, of the scalar dark matter particle and then compared to a standard model background process. Investigations are made whether or not it would be possible to detect darkmatter signals in the background. With the assumptions made, the results indicate that a signal from dark matter with a mass of around 40−150 GeV could not be rejected up to 5σ.

In 2027 the Large Hadron Collider (LHC) at CERN will enter a high luminosity phase, deliver- ing 3000 fb 1 over the course of ten years. The High Luminosity LHC (HL-LHC) will increase the instantaneous luminosity delivered by a factor of 5 compared to the current operation pe- riod. This will impose significant technical challenges on all aspects of the ATLAS detector but particularly the Inner Detector, trigger, and data acquisition systems. In addition, many of the components of the Inner Detector are reaching the end of their designed lifetime and will need to be exchanged. As such, the Inner Detector will be entirely replaced by an all silicon tracker, known as the Inner Tracker (ITk). The layout of the Pixel and strip detectors will be optimised for the upgrade and will extend their forward coverage. To reduce the per-pixel hit rate and explore novel techniques for deal- ing with the conditions in HL-LHC, an inter-experiment collaboration called RD53 has been formed. RD53 is tasked with producing a front-end readout chip to be used as part of hybrid Pixel detectors that can deal with the high multiplicity environment in the HL-LHC. A silicon sensor, which makes up the other half of the hybrid Pixel detector, must also be designed to cope with the high fluences in HL-LHC. Significant damage will be caused by non- ionising energy loss in the sensor over its lifetime. This damage must be incorporated into the detector simulation both to predict the detector performance at specific conditions and to understand the e↵ects of radiation damage on data taking. The implementation of radiation damage in the ATLAS simulation framework is discussed in this thesis. Collisions produced by the HL-LHC also presents a challenge for the current track reconstruc- tion software. High luminosity is obtained, in part, by increasing the number of interactions per bunch crossing, which in turn increases the time taken for track reconstruction. Various ap- proaches to circumvent the strain on projected resources are being explored, including porting existing algorithms to parallel architectures. A popular algorithm used in track reconstruction, the Kalman filter, has been implemented in a neuromorphic architecture: IBM’s TrueNorth. The limits of using such an architecture for tracking, as well as how its performance compares to a non-spiking Kalman filter implementation, are explored in this thesis.

No description available.

Chiral Perturbation Theory (ChPT) is a tool for studying the strong interaction at low energies. The Perturbation theory is developed around the limit where the light quarks, u,d,s are approximated to be massless. In this approximation the isospin symmetry, one of the main features of the strong interaction, is fulfilled automatically. The study of the light quark masses and isospin violation can be done with the η'→πππ and η'→ηππ decay channels by analyzing the kinematic distribution using so-called Dalitz plots. A Dalitz plot analysis of the η'→ηπ+π- decay mode is conducted by the BESIII collaboration. The unbinned maximum likelihood method is used to fit the parameters that describe the Dalitz plot distribution. In this fit a polynomial expansion of the matrix element squared is used. However, in order to study light quark masses, it is better to use a parameterization which includes the description of the final-state interaction based on a dispersion relation. Hence, it is desirable to use a representation of the Dalitz plot as a two-dimensional histogram with acceptance corrected data as input to extract the substraction constants. Therefore, the goal of this thesis is to make a consistency check between the unbinned and binned representation of the data. In this thesis Monte Carlo data of η'→ηπ+π- decay channel is generated based on the BESIII. An unbinned maximum likelihood fit is performed to find the Dalitz plot parameters repeating the BESIII analysis method. The Monte Carlo data is then used for a binned maximum likelihood and a χ2 fit. Finally, the prepared binned experimental acceptance corrected data from BESIII is used to fit the Dalitz plot parameters using the same statistical methods. The results based on the binned maximum likelihood and the χ2 methods are consistent with the fit using the unbinned maximum likelihood method applied in the original BESIII publication.

Neutron-rich rare-earth nuclei around the maximum of collectivity are predicted to exist with an extremely stable intrinsic configuration in their ground-state structure. Due to the high degree of axial symmetry and large deformation, these nuclei are also excellent candidates for having long-lived high-K isomers. The present work concerns a study of the structure of the yrast bands and a search for isomers in the neutron-rich 68Er isotopes. Excited states of 68Er isotopes were populated via multi-nucleon transfer reactions. A 859 MeV 136Xe-beam was used to bombard a 170Er-target. The experimental setup consisted of the high-resolution γ-ray spectrometer AGATA coupled to the heavy-ion magnetic spectrometer PRISMA. The experiment collected 2 TB of useful data corresponding to 3 days of effective beam time. Beam-like fragments were identified by the PRISMA specrometer placed at the grazing angle of 44 degrees. PRISMA allows for Z, A and q identification as well as TOF and velocity vector determination. This is required for the Doppler correction of the emitted γ rays detected in time coincidence with AGATA. A good Z and very clean A separation has been achieved in PRISMA. Making use of two-body kinematics, Doppler corrected γ-ray spectra for target-like fragments were obtained as well. Due to the novel techniques of PSA and γ-ray tracking, AGATA provided high-quality γ-ray spectra for both beam-like xenon and target-like erbium isotopes. Known yrast bands and isomeric states in neutron-rich erbium isotopes were observed. A candidate for the decay of an isomeric state with Eγ=184 keV  in 173Er, which has no previously known excited states, was identified.

A fundamental assumption of our universe has been that equal amounts of matter and antimatter were created during the Big Bang. Since the world we live in is made entirely of matter, one either needs to question this assumption, or explain how matter was enriched with respect to antimatter. This is a puzzle that scientists all over the world are trying to solve. Particle accelerator experiments like Belle II in Tsukuba, Japan, enable precision studies of the heavier siblings of protons, for example charmed baryons. Since these baryons are unstable, they offer a unique tool to understand the matter-antimatter-asymmetry of the universe: by comparing the decay-patterns of the baryons and antibaryons, we look for tiny differences in the interactions that, if they exist, can have led to the matter-antimatter imbalance. The project aims to examine the capacity of the Belle II generator, which is a crucial part of analysis in experimental particle physics. The aim of this project is also to develop a toolkit for estimating decay-parameters from baryon decay distributions: one single-step process and one multi-step process, and compare statistical properties of the estimators in order to see which one yields a more precise estimation.

No description available.

The aim of this thesis is to examine the hard $S$-matrix for QED and QCD, due to Hannesdottir and Schwartz [1], both recreating known results, and finding new results in lower dimensions. Electrons by themselves are not gauge invariant, and in the massless limit do not give finite $S$-matrix elements for individual processes; one needs to add together seemingly arbitrary combinations of diagrams in order to be able to calculate the scattering cross-section. One remedy is to exchange the bare electron for a dressed state, or equivalently to include the dressing in the $S$-matrix itself. This gives rise to a formalism in which one needs only consider time cuts of an individual diagram in order to find finite $S$-matrix elements. The main result of this thesis is the examination of the results which are found by Hannesdottir and Schwartz in a model system of fewer dimensions. This may be of use for toy model calculations in QCD, where 2+1-dimensional QED better models certain phenomena than does 3+1-dimensional QED.