Boomtown urbanization and rural-urban transformation in mining and conflict regions in Angola, the DRC and Zambia

Starting from temporary settlements turning into permanent urban centers, this paper discusses the transformations taking place through the process of so-called ‘boomtown’ urbanization in Central and Southern Africa. Based on data collected in Angola, Zambia and the Democratic Republic of Congo, the paper identifies the different conditions for migration and settlement and the complex socio-economic, spatial, as well as political transformations produced by the fast growth and expansion of boomtowns. Different historical and contemporary processes shape boomtown urbanization in Africa, from colonial territorial governance to large- and small-scale mining or dynamics of violence and forced displacement. As centers of attraction, opportunities, diversified livelihoods and cultures for aspiring urbanities, boomtowns represent an interesting site from which to investigate rural-urban transformation in a context of resource extraction and conflict/post conflict governance. They equally represent potential catalyzing sites for growth, development and stability, hence deserving not only more academic but also policy attention. Based on the authors’ long-term field experience in the countries under study, the analysis draws on ethnographic fieldwork data collected through observations as well as interviews and focus group discussions with key actors involved in the everyday shaping of boomtown urbanism. The findings point to discernible patterns of boomtown consolidation across these adjacent countries, which are a result of combinations of types of migration, migrants’ agency and the governance structures, with clear implications for urban policy for both makeshift and consolidating towns

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Beta-decay study of the halo nuclei 6He, 11Be and 11Li.

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UnhideWhenUsed="false" Name="Colorful Grid Accent 6"/> UnhideWhenUsed="false" QFormat="true" Name="Subtle Emphasis"/> UnhideWhenUsed="false" QFormat="true" Name="Intense Emphasis"/> UnhideWhenUsed="false" QFormat="true" Name="Subtle Reference"/> UnhideWhenUsed="false" QFormat="true" Name="Intense Reference"/> UnhideWhenUsed="false" QFormat="true" Name="Book Title"/> /* Style Definitions */ table.MsoNormalTable {mso-style-name:Standaardtabel; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}Kernstructuurstudies stellen ons in staat eenbeter begrip te krijgen van de fundamentele krachten die spelen in de natuur envan de manier waarop de materie is opgebouwd. Dit doctoraatswerk legt deklemtoon op het beta verval van lichte exotische kernen, gelegen op dekernkaart vlakbij de druppellijn en gekenmerkt door een zogenaamde halostructuur.De implantatiemethode die werd toegepast indit werk, werd speciaal ontworpen voor de meting van vervalkanalen waarbijgeladen deeltjes worden uitgezonden nadat er een beta verval heeftplaatsgevonden. Radioactieve ionenbundels worden rechtstreeksgeïmplanteerd in een zeer dunne, sterk gesegmenteerde siliciumdetector en het daaropvolgende verval wordt geobserveerd in hetzelfde kleinedetectievolume. De voordelen van deze techniek ten opzichte van meertraditionele detectoropstellingen worden uitvoerig besproken in deze thesis.GEANT4 simulaties werden gebruikt om de experimentele resultaten beter tekunnen begrijpen en relevante informatie hieruit te extraheren. De metingen dieworden behandeld in dit werk, werden allemaal uitgevoerd met behulp vannaversnelde radioactieve ISOL bundels aan verschillende experimentelefaciliteiten. In een eerste reeks van experimenten aan hetCRC-UCL in Louvain-la-Neuve, België, werd het beta-vertraagde alpha + d emissiekanaal in het verval van 6He bestudeerd. De absoluteovergangswaarschijnlijkheid B = (1.65 +/- 0.10) x 10 -4 werd bepaaldvoor de absolute overgangswaarschijnlijkheid. Er werd vastgesteld dat ditverval sterker is dan het 9Li + d emissiekanaal. Er werd duidelijk aangetoond dat deimplantatietechniek met een zeer sterk gesegmenteerde silicium detector uiterstadekwaat is voor de meting van zwakke beta-vertraagde vervalkanalen waarbijgeladen deeltjes worden uitgezonden en die waardevolle kernstructuur opleveren.Dit onderzoekswerk vult de kennis van goed bestudeerde halo kernen aan maaropent van de andere kant ook vragen die in de toekomst kunnen worden behandeldin experimenteel en theoretisch onderzoek.Acknowledgements i Abstract (English) iii Abstract (Nederlands) v List of Tables ix List of Figures xi Introduction 1 1 Light exotic nuclei 5 1.1 Nuclei close to the driplines . . . . . . . . . . . . . . . . . . . . 5 1.2 Production mechanisms for light exotic nuclei . . . . . . . . . . 5 1.3 Halo nuclei . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.3.1 Reaction studies of halo nuclei . . . . . . . . . . . . . . 9 1.3.2 Beta-decay studies of halo nuclei . . . . . . . . . . . . . . . 12 2 Experimental method: A calorimetric measurement after implantation 17 2.1 The double-sided silicon strip detector (DSSSD) . . . . . . . . 19 2.1.1 Electronics for data-taking and -readout . . . . . . . . . 22 2.2 Time profile of the radioactive ion beam . . . . . . . . . . . . . 24 2.3 Beta-suppression factor . . . . . . . . . . . . . . . . . . . . . . . . 26 2.4 Beta-summing effects - GEANT4 Monte Carlo simulation . . . . . 32 Paper I: Beta-decay studies with an implantation technique . . . . . . . 39 3 Charged-particle emission in the 6He beta decay 51 Paper II: Measurement of the branching ratio of the 6He beta-decay channel into the alpha + d continuum . . . . . . . . . . . . . . . . 51 4 Charged-particle emission in the beta decay of the one-neutron halo nucleus 11Be 65 4.1 Current knowledge of the beta decay of 11Be . . . . . . . . . . . . 65 4.2 Experimental setup . . . . . . . . . . . . . . . . . . . . . . . . . 70 4.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 4.3.1 The 8Li + t channel in the 11Li beta decay . . . . . . . . . 77 4.3.2 " emission in the 11Be beta decay . . . . . . . . . . . . . . 78 4.4 11Be beta-decay measurement at ISOLDE . . . . . . . . . . . . . . 93 4.4.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 93 4.4.2 Experimental Setup . . . . . . . . . . . . . . . . . . . . 95 4.4.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 4.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 4.5.1 Beta decay of 11Li towards the first excited state at 320 keV in 11Be . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 4.5.2 Beta decay of 11Be: a new state at 11.56 MeV in 11B . . . 116 4.5.3 Relative feeding of 7Li + alpha channels in the beta decay of 11Be120 4.5.4 The halo decay of 11Be . . . . . . . . . . . . . . . . . . 121 4.5.5 The 8Li + t channel in the 11Li beta decay . . . . . . . . . 122 Conclusions and outlook 125 A R-matrix formalism 129 A.1 The collision matrix . . . . . . . . . . . . . . . . . . . . . . . . 129 A.1.1 Level-matrix form of the collision matrix . . . . . . . . . 130 A.2 Scattering cross section . . . . . . . . . . . . . . . . . . . . . . 131 A.2.1 Single channel approximation . . . . . . . . . . . . . . . 133 A.2.2 Single level approximation . . . . . . . . . . . . . . . . . 133 A.3 Beta decay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 A.3.1 Beta-decay matrix elements . . . . . . . . . . . . . . . . . . 135 A.4 Alternative parametrization without boundary conditions . . . 136 A.5 Application in the beta decay of 11Be . . . . . . . . . . . . . . . . 137 A.5.1 Phase space . . . . . . . . . . . . . . . . . . . . . . . . . 138 A.5.2 Shift function and penetrability . . . . . . . . . . . . . . 140 Bibliographynrpages: 167status: publishe

Reactive Power Support in Residential LV Distribution Grids through Electric Vehicle Charging

This article discusses the impact of reactive power support of single-phase electric vehicle chargers, during charging, in a low-voltage residential distribution grid. For a representative Flemish case study, reactive power support is investigated for three different electric vehicle charging strategies: uncoordinated charging, residential off-peak tariff charging, and vehicle-based peak shaving. For an increasing electric vehicle penetration rate and an increasing amount of reactive power injection, the impact on the residential voltage deviations, peak load, and grid losses is calculated. The results of the case study show that the implementation of a capacitive load behavior in electric vehicle chargers has a beneficial impact on the voltage deviations. Furthermore, for a capacitive power factor of 0.95 or higher, there is no disadvantage with respect to the residential peak load and the residential grid losses. However, the cost related to the increased apparent power rating of the vehicle chargers, required to supply the reactive power, should be assessed compared to the mentioned advantages. If the benefits outweigh the costs, reactive power support could be considered in the grid compliance requirements of electric vehicle chargers, as it allows deferring distribution grid infrastructure investments.status: publishe

Impact of Electric Vehicle On-Board Single-Phase Charging Strategies on a Flemish Residential Grid

This paper quantifies the impact of single-phase on-board charging strategies for electric vehicles (EVs) in a case study of a heavily loaded unbalanced Flemish three-phase low-voltage residential grid. Voltage droop charging and EV-based peak shaving, which do not need communication with the distribution grid, are modeled and the results are compared. The grid voltages are analyzed according to the probabilistic and deterministic limits of the EN50160 standard, for a 100 % EV penetration rate. The impact on the EV user comfort is evaluated in terms of charging time and electrically driven distances. The chosen voltage droop charging eliminates critical voltages below 0.85 pu and reduces voltage unbalance, with a limited impact on the total charging time. EV-based peak shaving makes the grid fully compliant with EN50160 and avoids the need for an infrastructure upgrade. The electrically driven distances are not influenced by the charging strategies.status: publishe