Public defence in Photonics and Nanotechnology, M.Sc. Xiaopeng Wu

The title of the thesis is Advanced Radiation Detectors for Particle Physics and Medical Imaging
A processed GaAs epitaxy wafer with various radiation detectors.

M.Sc. Xiaopeng Wu will defend the thesis "Advanced Radiation Detectors for Particle Physics and Medical Imaging" on 25 November 2022 at 12 (EET) in Aalto University School of Electrical Engineering, Department of Electronics and Nanoengineering, in lecture hall AS1, Maarintie 8, Espoo, and online in Zoom.

Opponent: Prof. Christer Fröjdh, Mid Sweden University, Sweden
Custos: Prof. Hele Savin, Aalto University School of Electrical Engineering, Department of Electronics and Nanoengineering

The public defence will be organized via remote technology. Follow defence:
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Public defence announcement:

The thesis focuses on design, fabrication and characterization of advanced radiation detectors which can be used for particle tracking in high energy physics experiments and medical imaging. The main purpose of this study is to design novel detectors, develop fabrication processes and prove detector performance with various characterization techniques. The study includes silicon edgeless pixel detectors, strip detectors fabricated on Magnetic Czochralski silicon (MCz-Si), and detectors manufactured on high purity GaAs epitaxial wafers. The edgeless detectors minimized insensitive region at the edge of detectors and enable the detector to be tiled in four directions. The MCz-Si material has strong robustness against harsh radiation. The strip detector fabricated on this material is proven to be used for particle tracker. Detector-grade high purity epitaxial GaAs wafers have been difficult to be obtained due to the challenges to grow the material. This study covered building of a Chloride Vapor Phase Epitaxy (CVPE) reactor to grow GaAs epitaxial material, and proof of fabrication of GaAs detectors using the epitaxy wafers.

This work studies different types of novel detectors, their fabrication techniques and develops methods to characterize materials and fabricated detectors. The knowledge developed from this work can be further used to customize radiation detectors for specific applications.

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