Speaker
Description
In this work we report the initial results of the first ultra-cold argon gas Time Projection Chamber (Ar-TPC) demonstrator developed at Astrocent, instrumenting both primary (S1) and secondary (S2) scintillation signals using a single optical readout plane, blind to Ar scintillation. This milestone represents a significant step forward in the development of compact, high-performance Ar-TPC technology for direct dark matter searches.
The novelty of this work lies in the use of wavelength-shifting optical amplification structures, wavelength-shifting FAT-GEMs (field assisted transparent gaseous-electroluminescence multipliers), instead of the standard and widely-used meshes in ultra-cold Ar gas (about -180 C). By integrating a wavelength shifter directly into these optical amplification structures it is possible to convert the vacuum ultraviolet (VUV) scintillation produced by argon (peaked at 128 nm) into the visible region, enabling efficient detection by standard blue-sensitive silicon photomultipliers (SiPMs). This dual functionality, simultaneous optical amplification and wavelength shifting, allows to improve the signal collection efficiency, with this structures allowing already to reach scintillation yields similar to the ones originated in meshes.
For this initial characterization of the setup, an alpha-particle source was used. Results demonstrate the wavelength-shifting FAT-GEM's capability to efficiently convert and collect scintillation signals originated in ultra-cold Ar in a single readout plane. This solution, apart from simplifying the optical readout, enables the development of back-to-back TPC solutions. In addition to the detailed description of the proof-of-concept demonstrator, we will present the initial results of the characterization of these novel optical amplification structures highlighting its potential for dark matter searches.
The results presented serve as a stepping stone for a wider research programme aiming at demonstrating the FAT-GEM technology as a promising and scalable solution for dual-phase liquid TPCs, aiming at tonne-scale.
| Main Contribution topic | Instrumentation for Dark Matter searches |
|---|---|
| Secondary contribution topic | Direct detection |