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U.S Gulf coast salt domes. Salt dome demographics: Several hundred known—some are good source of oil Typical ~3-5 km diameters, 5-15 km deep ~200 km 3 water equiv. in top 3-5 km for many domes. Hockley dome/mine. Houston. New Orleans. Salt Measurements at WIPP & Hockley.
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U.S Gulf coast salt domes • Salt dome demographics: • Several hundred known—some are good source of oil • Typical ~3-5 km diameters, 5-15 km deep • ~200 km3 water equiv. in top 3-5 km for many domes Hockley dome/mine Houston New Orleans
Salt Measurements at WIPP & Hockley • Supported through UCLA: DOE ADRP grant (Saltzberg) • Results posted at hep-ex, submitted to NIM: • WIPP: not so good……. Hockley Mine: very promising!
Results from Hockley Mine rock salt tests • All results consistent with >200 meter attenuation lengths • Supported by ground-penetrating radar results since early 1970’s • Radar pulses sent through ~3 km of salt in some Gulf-coast salt domes
Summary of WIPP/Hockley results • Rock salt is perhaps the clearest medium known for EM propagation • Usable frequency range from few MHz to ~10 GHz • Evaporite beds (WIPP) have problems with impurities, but salt domes appear to be often purified through geologic processes • No measureable bi-refringence or depolarization • Allows for possibility of polarization tracking • May be better than ice in this respect • Several other salt domes known to be as good or better than Hockley • Avery Island (LA), Weeks Island (LA) • Cote Blanche (LA), Grand Saline (TX) • Many others expected to be excellent but as yet unmeasured • Typical salt volume 50-100 cubic km per salt dome • Several hundred known known salt domes in Gulf coast area, probably thousands throughout the world
Properties of materials forUHE Neutrino Detector Rock salt: high density, large refractive index and short radiation length From M. Chiba
Measurements of complex permittivity of rock salts and lime stones Cavity perturbation method Absorption depends on the surface condition of the samples, e.g. smoothness, stain etc. • 9.4GHz TE107 • Q=4000 • Size: 23x10x155mm3 • 1GHz TM010 • Q=10000 • Size: 230mmf x 30mm
Samples measured around 10GHz • Rock salt is fragile, so that it is not easy to make small stick samples ( 1mm x 1mm x 10.2mm ). Lime stone (especially Jura lime stone ) is rigid. The small stick samples are obtained using a milling machine.
Attenuation length Dielectric resonator M.Chiba