LUX-ZEPLIN

Abstract:

Radiowave detection of the Cherenkov radiation produced by neutrino-ice collisions requires an understanding of the radiofrequency (RF) response of cold polar ice. We herein report on a series of radioglaciological measurements performed approximately 10 km north of Taylor Dome Station, Antarctica from Dec. 6, 2006 - Dec. 16, 2006. Using RF signals broadcast from a dual-polarization horn antenna on the surface transmitting signals which reflect off the underlying bed and back up to a dual polarization surface horn receiver, we have made time-domain estimates of both the real (index-of-refraction "n") and imaginary (attenuation length "Latten") components of the complex ice dielectric constant (ε = ε′ +iε′ ′). We have also measured the uniformity of ice response along two orthogonal axes in the horizontal plane. We observe an apparent wavespeed asymmetry of order 0.1%, between two orthogonal linear polarizations projected into the horizontal plane, consistent with some previous measurements, but somewhat lower than others.

Abstract:

The ANtarctic Impulse Transient Antenna (ANITA) is the first long-duration balloon experiment designed to search and measure the flux of Greisen- Zapsepin-Kuzmin (GZK) neutrinos. We present new limits on neutrinos fluxes of astronomical origin from data collected with the successful launch of a 2- antenna prototype instrument, called ANITA-lite, that circled the Antarctic continent for 18.4 days in January 2004. We performed a search for Ultra- High-Energy (UHE) neutrinos with energies above 3 x 1018 eV. No excess events above the background expectation were observed and a neutrino flux following E-2 spectrum for all neutrino flavors, is limited to Ev-2F < 1.6 × 10-6 GeV cm-2 s-1 sr-1 for 1018.5 eV < Ev < 1023.5 eV at 90% confidence level. The launch of ANITA is scheduled for December 2006. Looking beyond ANITA, we describe a new idea, called ARIANNA (Antarctic Ross Iceshelf ANtenna Neutrino Array), to increase the sensitivity for GZK neutrinos by one order of magnitude better than ANITA. Copyright © 2007 by World Scientific Publishing Co. Pvt. Ltd.

Abstract:

The temperature dependence of the decay time and scintillation light yield of pure CaF2 crystal was measured over the temperature range 8-305 K using the multiphoton coincidence counting technique. Pure CaF2 exhibits emission of triplet self-trapped excitons at 280 nm with a slow decay, the time constant of which changes significantly with temperature. The main decay time constant increases by three orders of magnitude when cooled, from 0.96±0.06 μs at 295 K to 930±40 μs at 8 K. The results obtained demonstrate that the scintillation light yield of pure CaF2 increases with decreasing temperature down to 20 K below which it is roughly constant. At low temperatures the light yield of CaF2 is estimated to be 60% relative to that of pure CaWO4. It is concluded that undoped calcium fluoride is a very attractive target material for experimental searches for rare events based on the detection of phonon and scintillation signals. © 2006 Elsevier B.V. All rights reserved.