The main field of interest of the INAF C.O.L.D. is photonics applied to astrophysical instruments. The main parameter of the detectors that plays an important role in photonics is the ability of the detector to transform each photon into a photo-electron. This parameter in technical jargon is called Quantum Efficiency (QE) and in the case of sensors operating in photon counting Photon-Detection Efficiency (PDE).

We believe that collaboration between research institutes and detector manufacturers is very important to study and develop detectors with suitable characteristics for astrophysical and scientific applications.
To check the real performance of the sensors, high accuracy instruments and appropriate measurement methods are required.

Since thirty years the INAF-COLD group has promoted and developed applied research in the field of solid-state sensors for astrophysical applications and has established long-term experience in the characterization of electro-optical sensors such as CCD (Charge Coupled Devices), IAPS (Intensified Active Pixel Sensor), SPAD (Single Photon Avalanche Diode), SiPM (Silicon Photon Multiplier) and in the design of related control systems.

The group is involved in technological innovation activities in the fields of microelectronics and nanotechnologies and has various collaborations all over the world with laboratories and manufacturers of detectors for both scientific and "life science" applications.
Detectors characteristics measurement (in particular SiPM-type photon counting systems) and study, design and implementation of front-end electronics are the strengths of the INAF-COLD laboratory.

The group maintains close working relationships with ST Microelectronics (present in the area), Hamamatsu Photonics (HPK) and collaborates with the University of Barcelona spin-off in the field of microelectronics and has a very intense and fruitful collaboration with the Department of Physics and Astronomy (DFA) of the University of Catania for the study and realization of muon trackers.

Recently we have undertaken a collaboration with the Lund Observatory (Sweden) in the field of intensity interferometry (II). This is a technique initiated by Hanbury-Brown and Twiss [HBT] for the original objective of measuring stellar dimensions and consists in evaluating the temporal correlations of the arrival times between the photons recorded in different telescopes to observe the secondary coherence of light. The technique was proposed to the CTA advisory committee and was included in the scientific cases provided for by CTA.

The competences of the COLD-INAF group make it possible to contribute positively both in the local area and in the national and international field, providing a consultancy and technology transfer service.
Some examples:

• Scientific projects such as CTA, ASTRI and volcano muography;
• Industrial projects (muonic portal for the detection of fissile material);
• Industrial projects in collaboration with Micro and Nano Technology Districts.

The main activities of the detector laboratory (COLD-INAF) can be summarized as follows:

• Basic research in Astrophysics and Physics;
• Characterization of detectors;
• Design and development of instrumentation for astrophysical applications from the ground and from space;
• Research and development applied to solid state sensors and information technology (ICT);
• Technology transfer.