Development of transparent silica aerogel over a wide range of densities

TL;DR

This paper reports the development of hydrophobic silica aerogels with a wide range of densities and refractive indices, achieved through a novel pinhole drying method, enhancing transparency and applicability in Cherenkov detection and cosmic dust collection.

Contribution

Introduction of a pinhole drying technique enabling precise control of silica aerogel density and refractive index over a broad range, including ultra-low densities.

Findings

Aerogels with refractive indices from 1.0026 to 1.26 were successfully produced.

Pinhole-dried aerogels demonstrated superior transparency compared to conventional aerogels.

Cherenkov ring imaging confirmed the effectiveness of the aerogels as radiators.

Abstract

We have succeeded in developing hydrophobic silica aerogels over a wide range of densities (i.e. refractive indices). A pinhole drying method was invented to make possible producing highly transparent aerogels with entirely new region of refractive indices of 1.06-1.26. Obtained aerogels are more transparent than conventional ones, and the refractive index is well controlled in the pinhole drying process. A test beam experiment was carried out in order to evaluate the performance of the pinhole-dried aerogels as a Cherenkov radiator. A clear Cherenkov ring was successfully observed by a ring imaging Cherenkov counter. We also developed monolithic and hydrophobic aerogels with a density of 0.01 g/cm^3 (a low refractive index of 1.0026) as a cosmic dust capturer for the first time. Consequently, aerogels with any refractive indices between 1.0026 and 1.26 can be produced freely.