  This study presents the advancement in hydrophobic silica aerogel development
for use as Cherenkov radiators and muonium production targets. These devices
are scheduled for use in several particle- and nuclear-physics experiments that
are planned in the near future at the Japan Proton Accelerator Research
Complex. Our conventional method to produce aerogel tiles with an intermediate
index of refraction of approximately 1.05 is extended so that we can now
produce aerogel tiles with lower indices of refraction (i.e., 1.03-1.04) and
higher indices of refraction (i.e., 1.075-1.08); each with excellent
transparency. A new production method, called pin drying, was optimized to
produce larger area aerogels consistently with an ultrahigh index of refraction
(>1.10). In addition, for use as a thermal-muonium-emitting material at room
temperature, dedicated low-density aerogels were fabricated using the
conventional method.
