AMANDA (Antarctic Muon and Neutrino Detector Array): A High Energy Neutrino Telescope at 1 km Depth

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Session 36 -- Particle Astrophysics
Display presentation, Tuesday, 9:30-6:30, Pauley Room

[36.04] AMANDA (Antarctic Muon and Neutrino Detector Array): A High Energy Neutrino Telescope at 1 km Depth

T. Miller, A. Goobar, D. M. Lowder, P. O'Leary, P. B. Price, A. Richards, D. Snowden-Ifft (UCB), S. W. Barwick, J. Lynch, R. Porrata, E. Schneider, G. Yodh (UCI), A. Bouchta, B. Erlandsson, P. O. Hulth, Q. Sun, C. Walck (Stockholm), S. Carius, L. A. Hallgren (Uppsala), A. Coulthard, K. Engel, L. Gray, F. Halzen, J. Jacobsen, V. Kandhadai, I. Liubarsky, R. Morse, S. Tilav (UW)

Detecting the small fluxes of neutrinos expected from astrophysical sources at energies greater than 1 TeV (10$^{12}$ eV) will require much larger neutrino telescopes than those existing today. Construction of such a large instrument ($\sim$ 1 km$^2$) will require taking advantage of a naturally occurring detector medium of enormous size, such as deep, clear Antarctic ice. We have begun the AMANDA (Antarctic Muon and Neutrino Detector Array) project to build such a large-scale detector by measuring the optical properties of in situ Antarctic ice. During the 1991-92 austral summer we placed a string of four 7.5 cm diameter photomultiplier tubes (PMTs) at a depth of 800 meters (700 mwe), and a string of four 20 cm diameter hemispherical PMTs at a depth of 150 meters, at the geographic South Pole. By comparing the count rates of observed cosmic ray muons to Monte Carlo predictions, we conclude that the optical attenuation length of the 800 meter deep ice is consistent with the laboratory result of 25 meters. This encouraging result implies that a neutrino telescope can be built by drilling holes in the ice, lowering strings of PMTs to $\sim$ 1 km depth, and then allowing the PMTs to freeze into the ice. Neutrinos can then be detected via Cerenkov light radiated by neutrino-induced muons created in the ice or rock below the array. We have used extensive Monte Carlo simulations to determine the most efficient design for AMANDA and show that background rejection sufficient to detect astrophysical point sources of neutrinos is possible. We now plan to deploy at least three strings of 20 cm PMTs, with 20 PMTs on each string, at the South Pole during the next (1993-94) austral summer, and to expand the array to 10 strings the following year.

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