Vertex detector for the SuperB factory

A new concept for a high-luminosity B-Factory (SuperB) has been recently proposed to deliver a luminosity greater than 1036cm-2s-1 with moderate beam currents. Comparing to current BFactories, the reduced center of mass boost of the SuperB machine requires improved vertex resolution for optimal time dependent measurements, which form the basis of the SuperB scientific program. Design studies indicate that such improved resolution is achievable with a vertex detector based on the BABAR silicon vertex tracker layout with the addtion of an innermost Layer 0 at radius of about 1.5 cm, with a material budget of about 0.5% X0 and capable to sustain a background rate of about 5 MHz/cm2. Several options for the Layer 0 design are reviewed in this paper. CMOS Monolithic Active Pixels (MAPS) is the most promising technology but extensive R&D is needed to meet all the requirements. The most recent developments on a new CMOS MAPS sensor, based on Deep NWell (DNW), are discussed. The design of DNW CMOS MAPS has been recently proposed by the SLIM5 Collaboration to develop a thin pixel system with sparsified readout suitable for application in the SuperB Layer 0. Several prototype chips, realized with the STMicroelectronics 130 nm triple well process, have demonstrated that the design is viable with good sensitivity to electrons from 90Sr. Based on the new DNW MAPS design, a dedicated fast readout architecture to perform on-chip data sparsification is currently under development.