Adherence of p-Terphenyl (PTP) film on the dichroic filter used for the X-ARAPUCA device

Abstract

The adherence of the p-Terphenyl film to the substrate in the X-ARAPUCA dichroic filter is directly correlated with the long-term efficiency and durability of this device. This study presents the results of different cleaning methods established to analyze their contributions to the film's adherence to the substrate. The samples underwent analysis of their crystalline and morphological structure using XRD and AFM techniques. Three distinct techniques were employed in the adherence tests: ultrasonic bath, scratch test, and cryogenic immersion method with turbulence, as these devices will be submerged in liquid argon in the DUNE experiment. Results suggest that the deposited PTP layer exhibits a monoclinic crystalline structure, with topography revealing percolated planar grains and roughness ranging from 13 nm to 18 nm. The various adherence techniques employed yielded consistent results, highlighting the standard cleaning process involving Soap + H2O + N2 + Kiln as the preferred method.