Towards the TRISTAN detector: Characterization of a 47-pixel monolithic SDD array

Multi-pixel Silicon Drift Detectors (SDD), widely employed in X-ray applications, can also be applied to electron spectroscopy experiments. The objective of the TRISTAN project is to equip the KATRIN beam line with a multi-pixel SDD focal plane array. This would allow to extend the physics program of KATRIN, whose main goal is the determination of the neutrino mass via a precise measurement of the tritium beta decay spectrum close to the endpoint. An extension of the measurement interval would enable a sensitive search for physics beyond the standard model, in particular keV-scale sterile neutrinos, a prime dark matter candidate. The SDD technology guarantees excellent energy resolution and high throughput capabilities. A custom 47-pixel prototype, based on a monolithic SDD tile, has been developed and tested for the TRISTAN project. The full functionality of the system has been verified for all 47 channels. Good spectroscopic performance has been observed with a 55Fe X-ray source. This is a crucial step towards the realization of the final 21-fold 166-pixel TRISTAN focal plane detector.