Origami chip-on-sensor design: progress and new developments

The Belle II silicon vertex detector will consist of four layers of double-sided silicon strip detectors, arranged in ladders. Each sensor will be read out individually by utilizing the Origami chip-on-sensor concept, where the APV25 chips are placed on flexible circuits, glued on top of the sensors. Beside a best compromise between low material budget and sufficient SNR, this concept allows efficient CO₂ cooling of the readout chips by a single, thin cooling pipe per ladder. Recently, we assembled a module consisting of two consecutive 6'' double-sided silicon strip detectors, both read out by Origami flexes. Such a compound of Origami modules is required for the ladders of the outer Belle II SVD layers. Consequently, it is intended to verify the scalability of the assembly procedure, the performance of combined Origami flexes as well as the efficiency of the CO₂ cooling system for a higher number of APV25 chips.