Micromachined Si-Well Scintillator Pixel Detectors

In this thesis a new design is presented for the position-sensitive detection of radiation with sub-millimeter spatial resolution. It consists of a matrix of scintillation crystals encapsulated in well-type silicon sensors. The wells can be realised by means of deep reactive ion etching of a silicon wafer. Scintillation crystal material can be deposited into the wells, e.g. by evaporation techniques or as a powder with a binder. The light created on the absorption of a radiation quantum in the scintillator material is confined by the vertical silicon sidewalls, reflected at the top and collected at a photodiode at the bottom of the well. The signal generated by this silicon photodiode is proportional to the energy deposited by the radiation quantum in the scintillation material. The development of this new detector, the "micromachined Si-well scintillator pixel detector" is not yet completed. However, its principle and its elaborate processing based on three different technologies, i.e. the integrated circuits technology, the silicon micromachining and the scintillator research, have been extensively studied. The first prototypes of well sensor have been successfully tested for the detection of gamma rays, alpha particles and thermal neutrons, demonstrating the feasibility of such a device