Speaker
Description
The number of rare event search experiments using liquid argon as the active volume is increasing. As the scintillation light emitted from liquid argon following the interactions peaks at 128 nm, a wavelength shifter (WLS) is required for efficient detection of such signals. In the experimental setup dubbed 2PAC (2 Parallel Argon Chambers) operated at LNGS, two identical liquid argon detectors are used to compare two WLS candidate materials: PolyEthylene Naphthalate (PEN) and TetraPhenyl Butadiene (TPB). In each chamber, the inner surface is covered with specular reflectors and one of the candidate WLS, while SiPMs are used as photosensors, covering approximately 1% of surface area, in order to imitate the configuration of the future large scale detectors. Experimental results of the light yield from both chambers, supported by the Geant4 simulations, will be discussed and compared, giving the first low temperature comparison of the wavelength shifting efficiencies of PEN and TPB in a true 4pi geometry, and the highest reported so far PEN conversion efficiency from an industrial grade of PEN. Future R&D plans for PEN as WLS will also be discussed.
