APiX2 - Avalanche Pixel Sensor for tracking applications

Goal of APIX2 project is the proof-of-concept implementation and preliminary evaluation of a new type of silicon sensor based on Geiger-mode avalanche detectors, suitable for particle tracking and imaging. The proposed device, formed by two vertically-aligned pixelated detectors, exploits the coincidence between two simultaneous avalanche events to discriminate between particle-triggered detections and dark counts.

The Science

APiX2 will develop an innovative position-sensitive pixelated sensor to detect ionizing particles. The APiX sensor will be based on the vertical integration of avalanche pixels connected in pairs and operated in coincidence in fully digital mode with on-chip embedded electronics. The APiX sensor addresses the need to minimize the material budget and related multiple scattering effects in tracking systems requiring a high spatial resolution in the presence of a large occupancy. The expected operation of the new sensor features low noise, low power consumption and suitable radiation tolerance.
The APiX device provides on-chip digital information on the position of the coordinate of the impinging charged particle and can be seen as the building block of a modular system of pixelated arrays, implementing a sparsified readout. The technological challenge of the vertical integration of the device, under CMOS processes and integration of on-chip electronics is performed in steps along a 3 years period, starting with a proof-of-concept approach.


• Involved external institutions: /
• INFN groups: Siena, Pisa, Pavia, TIFPA, Padova
• Principal Investigator: P. S. Marrocchesi (INFN Pisa)
• INFN Project: CSN V
• Duration: 3 years (July 2014 - July 2017)


• Local responsible for TIFPA: Lucio Pancheri
• Involved TIFPA people: Gian-Franco Dalla Betta, Moustafa Ahmed Soliman Khatib, David Macii, Giovanni Verzellesi, Hesong Xu