Ultimately, the answer to the question about the fundamental nature of dark matter must come from the lab. It is only through a direct observation in a controlled experiment that we can hope to pin down these particles and systematically investigate their properties. As we are currently in the dark about what their mass is and how they interact with ordinary particles, experimental searches must necessarily be diverse and span over several techniques. They must range from collider searches at the highest energy frontiers, to underground noble liquid detectors, to novel target materials at the edge with solid state physics. The Physics department plays a leading role in all of these directions.  

The research groups of the ATLAS and CMS experiments at the Department of Physics and the INFN Section of Sapienza University of Rome are actively involved in the search for different dark matter candidates, ranging from the notorious Weakly Interacting Massive Particles (WIMPs) to alternative models for the dark sector. This is done through advanced data analysis and artificial intelligence techniques developed for the CERN LHC collider. In parallel, the groups carry out research and development activities on innovative detectors based on advanced technologies for experiments at future particle colliders, with the goal of further expanding the capability to investigate the nature of dark matter.

Our researchers have also given foundational contributions to existing underground experiments like DarkSide. The latter hunts dark matter using liquid and gaseous Argon, and tries to detect the signatures of the scattering of a dark matter particle off these atoms. The next generation of such a detector, DarkSide-20k, is under construction, and it is expected to place world leading bounds on a number of dark matter models: from GeV dark matter interacting with nucleons or electrons, to lighter candidates like dark photons, axions and sterile neutrinos. The Physics department is an essential member of the DarkSide collaboration, and has given crucial contributions towards shaping its present and future strategies.
 

Foundational results have also been obtained within the CYGNO collaboration. The aim of this project is to realize a 3-dimensional imaging of the track left by the dark matter recoiling off the target. Thanks to this, CYGNO will be able to infer the direction of the incoming dark matter particle that caused the track in the first place. This is an extremely powerful tool to help discriminate between an event truly due to dark matter, and an event due to unwanted but ineliminable background. Indeed, while dark matter particles mostly arrive at our detectors from the direction of the Cygnus constellation, background events are expected to come pretty much from anywhere.    
 

Finally, the Physics department is pioneering the development of completely new detectors, envisioned to be sensitive to very small energy deposits, and therefore able to look for dark matter particles lighter than those probed by more traditional searches. A new class of detectors has been developed here based on superconducting sensors that act like ultra-sensitive microphones, capable of identifying the subtle pings of light dark matter particles hitting a silicon target. The effect of this collision is to produce vibrations in the target, causing a small disruption of the superconductor and the observation of the signal. This effort led to the creation of BULLKID-DM, an experiment for light dark matter under construction in our Department, which will be relocated to the Gran Sasso Underground laboratory for the actual measurement in one year.  The detection of light dark matter is further explored within the Department by leveraging the unique properties of carbon nanotubes, which are also target material sensitive to the direction of the incoming dark matter.

By combining these innovative micro-sensors with large-scale detection programs, the Department is ensuring that no potential dark matter signal remains out of reach.

People:

• Giacomo Artoni (ATLAS)

• Cesare Bini (ATLAS)

• Gianluca Cavoto (CYGNO and carbon nanotubes target)

• Leticia Cunqueiro Mendez (CMS)

• Sandro de Cecco (DarkSide)

• Daniele Del Re (CMS)

• Stefano Giagu (ATLAS)

• Marumi Kado (ATLAS)

• Claudio Luci (ATLAS)

• Andrea Messina (DarkSide and CYGNO)

• Giovanni Organtini (CMS)

• Riccardo Paramatti (CMS)

• Shahram Rahatlou (CMS)

• Francesco Santanastasio (CMS)

• Marco Vignati (BULLKID-DM)

• Cecilia Voena (ATLAS)