Speakers
Description
The CYGNO collaboration is developing a novel directional gaseous detector aimed at the direct detection of rare events, with particular sensitivity to low-mass Dark Matter candidates (below a few tens of GeV/c²). The detector is based on a Time Projection Chamber (TPC) operated at atmospheric pressure with a He:CF₄ gas mixture, and equipped with a triple Gas Electron Multiplier (GEM) amplification stage. Exploiting the scintillation properties of the gas, the detector adopts an optical readout system combining sCMOS cameras and photomultiplier tubes, enabling three-dimensional reconstruction of both electron and nuclear recoils down to the keV scale.
In the context of low-energy rare event searches, minimizing the detectable energy threshold is essential to enhance both directional sensitivity and Dark Matter discovery potential. Although optical readout allows coverage of large detector areas with relatively few sensors, photon collection is inherently limited by the reduced solid angle, thus requiring very high avalanche gains. However, these gains are constrained by space-charge saturation effects in the amplification stage. In this talk, we present a detailed model of space-charge saturation based on measurements performed with a CYGNO prototype. We also report on several experimental strategies developed to mitigate this limitation while preserving high effective gain. These include the implementation of V-Bond-treated GEMs and the application of strong electric fields (exceeding 10 kV/cm) below the third GEM to modify the electric field configuration and enhance light production. Addressing gain limitations in optically readout gaseous detectors is a key challenge for rare event searches, and the techniques presented here represent promising steps toward scalable, next-generation experiments.
| Name of the speaker | Stefano Piacentini |
|---|---|
| Eligible for the Georges Charpak Young Scientist Award. | yes |