Highly Transparent Aerogel with Refractive Index < 1.01 for High Energy Particle Detection

Aerogel of high optical quality is needed for hadron identification in nuclear physics experiments in the momentum range 3 - 8 GeV/c, where other techniques are not effective. The large-volume aerogel Cherenkov detectors for the Electron-Ion Collider (EIC) and those in three halls at the Jefferson Lab require high-quality, hydrophobic aerogel material. This Phase I/II project addresses this need with the development of aerogels with a refractive index as low as 1.008 to identify particles at the higher momenta and with increased tile sizes up to 20 x 20 x 3 cm3 while maintaining good optical and hydrophobic properties. Phase I established the fabrication techniques for producing small batches (10-20 tiles) of aerogel with refractive index <1.01 and nominal dimensions 10 x 10 x 1 cm3. The new aerogels are hydrophobic, radiation hard, and exhibit excellent optical properties, as well as up to ~30% higher light yield than currently available aerogels. The feasibility for scaling up the size was demonstrated with the production of 20 x 20 x 3 cm3 tiles. In addition, a novel method was developed to mechanically reinforce low refractive index aerogels, which could improve their fabrication, handling, and use in Cherenkov detectors. Phase II will establish the definite light yield/efficiency of the aerogels developed in Phase I in the limit of very fast particles in a particle beam test program. Production capability for larger numbers of uniform tiles will be developed to meet the need of large-volume Cherenkov detectors. The second goal of Phase II is to complete simulation studies, produce the mechanically reinforced low- refractive index aerogels, and to validate their optical properties necessary for Cherenkov detectors in a beam test program. The market for Cherenkov detectors has been growing over the last years with new aerogel-based detectors being built for Jefferson Lab and being planned for new and future facilities like the EIC. The availability of low refractive index aerogel of large tile sizes and thickness, as well as improved strength, would be a major step forward in aerogel detector technology, and it is expected that the tiles would find immediate application in nuclear physics experiments. The ability to manufacture high quality monolithic aerogels will prove useful not only for Cherenkov detection but also for fenestration or window thermal insulation applications that would significantly save energy and protect the environment via lower energy consumption. Transparent aerogels will find use in the Building and Construction market as insulated translucent windowpanes.