The DIAPHANE project is pluri-disciplinary collaboration between particle and ge o-physicists to perform the tomography of large geological structure mainly devoted to the study of active volcanoes. The detector used for this tomography, hereafter referred to as telescope, uses a standard, robust, cost-effective and well-known opto-electronics technology based on photomultipliers (either multichannel pixelized PM or silicon PM). The electronics system is built on the concept of autonomous, triggerless, smart sensor directly connected on a standard fast Ethernet network. In this talk the potential of the technique is detailed and discussed in the context of underground laboratories (long-term storage problems) and of active volcanoes. I will present recent results obtained on the Lesser Antilles volcanoes (Soufrière of Guadeloupe, Soufriere Hills of Montserrat), on the Etna in Sicily and on the Mayon in the Philippines.
In particular I will show how the technique improved with time (embedding a sub-nanosecond resolution TDC within the existing programmable logic to reject background) and allows nowadays to monitor the activity of phreatic volcanoes and to constrain the geophysical models.

Institut de Physique Nucléaire de Lyon - Université de Lyon - CNRS/IN2P3 - UMR 5822

Géosciences Rennes - Université de Rennes - CNRS/INSU - UMR 6118