The PhD defence and trial lecture will be streamed. The chair of the defence will moderate the disputation.
Ex auditorio questions: the chair of the defence will invite the audience physically present in the auditorium to ask ex auditorio questions.
→ Live streaming of trial lecture and disputation
→ Request for thesis copy (available until the disputation starts)
Trial lecture
Time and place: September 20, 2024; 10:15 AM, - Lille Fysiske auditorium (V232) - Fysikkbygningen
Title: “Advancements in gaseous detector technologies for high energy physics”
Main research findings
The future generations of particle physics experiments put stricter demands on the detectors as both the integrated and instantaneous luminosities increase. The higher instantaneous luminosity will make particle track reconstruction more challenging, and the higher integrated luminosity leads to more radiation damage. To cope with this, the sensors must be made more radiation hard and faster than they are today. This thesis suggests, presents and studies a new semiconductor sensor concept, the Silicon Electron Multiplier (SiEM), which aims to fulfill these requirements in a single device. The sensor contains additional electrodes in the substrate that can be biased to induce charge multiplication. TCAD-simulations gave encouraging results, and a fabrication study was initiated. Metal Assisted Chemical Etching (MacEtch) was applied in this work to produce a SiEM demonstrator by etching an already implanted silicon wafer. The structures were measured for their current—voltage characteristics which showed a preserved pn-junction after processing. Initial pulse measurements have shown that the device responds to ionising radiation. In addition to the SiEM project, the thesis contains the first steps towards the Timepix4 telescope, where four Timepix4 planes have been used to reconstruct charged particle tracks.
Hovedfunn (Norwegian)
Fremtidens partikkelfysikk-eksperimenter setter strengere krav til detektorene ettersom både antallet partikkelkollisjoner per tid og den totale strålingsbelastningen vil øke. Økt antall kollisjoner per tid vil gjøre rekonstruksjon av partikkelbaner mer krevende, og en økt total strålingsbelastning vil føre til mer strålingsskade på sensorene. For å imøtekomme dette må sensorene bli laget mer strålingsharde og raskere enn de er i dag. Denne avhandlingen foreslår og utvikler et nytt halvledersensor-konsept som skal imøtekomme disse kravene, kalt «The Silicon Electron Multiplier». Sensoren inneholder ekstra elektroder som kan påføres spenning for å gi et lokalt høyt elektrisk felt som bidrar til ladningsmultiplikasjon og signalforsterkning. Simuleringer ga lovende resultater og en produksjons-studie ved å bruke metall-assistert kjemisk etsnings (MacEtch) ble gjennomført. Strømmen i de produserte tekststrukturene ble målt som funksjon av spenning og viste at pn-overgangen var bevart. Innledende pulsmålinger har vist at sensoren responderer på ioniserende stråling. I tillegg til SiEM-prosjektet inneholder avhandlingen de første stegene mot et Timpix4-partikkelteleskop der fire Timepix4-detektorer har blitt brukt til å rekonstruere partikkelbaner.
Adjudication Committee
- Dr. Georg Steinbrück, Institute of Experimental Physics, Faculty of Mathematics, Informatics and Natural Sciences, Universität Hamburg, Germany
- Associate Professor Avisek Roy, Department of Microsystems, Faculty of Technology, Natural Sciences and Maritime Sciences, University of South-Eastern Norway
- Professor Lasse Vines, Department of Physics, the Faculty of Mathematics and Natural Sciences, University of Oslo, Norway
Supervisors
- Professor Heidi Sandaker, Department of Physics, University of Oslo, Norway
- Dr. Victor Coco, CERN, Switzerland
Chair of defence
Professor Anette Eleonora Gunnæs, Department of Physics, University of Oslo, Norway
Candidate contact information
LinkedIn: https://www.linkedin.com/in/m-m-halvorsen/
Contact information to Department: Line Trosterud Resvold