|Development of an Avalanche Pixel Sensor for tracking applications
|Development of an Intra-Operative
Probe for Radio Guided Surgery
Participating INFN groups: Siena/Pisa, Padova, Pavia, Trento (TIFPA)
Projects: APIX2, ASAP (Array of Silicon Avalanche Pixels))
National coordinator: P. S. Marrocchesi, University of Siena and INFN Pisa
Local coordinators: L. Pancheri (TIFPA), L. Ratti (Pavia), G. Collazuol (Padova), P.Marrocchesi (Pisa/Siena)
The APiX2 project successfully developed an innovative position-sensitive pixelated sensor to detect ionizing particles. The APiX sensor is 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 new sensor features low noise, low power consumption and suitable radiation tolerance for radiation imaging applications in space experiments, nuclear medicine and industrial controls.
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 digital arrays, implementing a sparsified readout. As the detector has internal gain (by the avalanche mechanism) the upper layer can be thinned down to a few tens of micron. The largest technological challenge is the vertical integration of the device, under CMOS processes and integration of on-chip electronics. The first two-prototypes were implemented with a micro bump-bonding techique. Further development with TSV based vertical integration is under consideration.
The ASAP projects takes advantage of the real-time imaging capabilities of the new sensor to explore its application in RGS (Radio Guided Surgery). Prototypes of an imaging probe have been built and successfully tested with a beta source. A wireless readout is also being implemented in Pavia.