Characterization of new Belle-type DEPFET pixel test structures

Sumitted to PubDB: 2026-05-01

Category: Master Thesis

Tags: PXD

Principal Authors Erik Buechau
Date 2025-10-05
Belle II Number BELLE2-MTHESIS-2026-012
Abstract Many particle detectors worldwide are used to gain deeper insights into the mechanisms of the universe's smallest constituents. Some detectors use natural particle sources, for example radioactive isotopes orcosmic radiation from the sun. In this case, the particle type and its properties are determined by external conditions. However, to meet specific experimental requirements, scientists developed particle accelerators as tunable sources. The most common use of particle accelerators is in colliders, where particles with adjustable properties collide and produce new particles. Typical tunable properties include energy, particle type and collision symmetry (symmetric or asymmetric). Since the resulting particles strongly depend on these conditions, various collider configurations have been built to study their characteristics. One example is the SuperKEKB accelerator in Japan, whose collisions are studied with the Belle II detector. A major goal of Belle II is to investigate CP violation in B-meson decays. To reconstruct interactions, the detector measures various particle properties including their trajectories. Therefore the detector consists of many elements. The innermost layer of the detector is the Pixel verteX Detector (PXD), which employs DEPFETs (DEpleted P-channel Field Effect Transistors) as pixels to reconstruct the particle tracks. DEPFET technology combines particle detection and in-pixel amplification, making it a self-amplifying active pixel sensor. This thesis focuses on the analysis of a new prototype of DEPFET matrices, compared to those currently used in the BELLE II experiment. Chapter 2 and Chapter 3 provide an overview of the BELLE II experiment and the DEPFET technology. In Chapter 4, static measurements are presented to later validate tests done with full assemblies. The results for assemblies of the known PXD9 type are presented in chapter 5 and compared to the PXD13 matrices. Chapter 6 presents additional studies done with similar structures.
Institute Bonn

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