Neutrino measurements with the IMB director

Abstract

The measure fraction of muon-like, single-track, atmospheric neutrino events over a 7.7 kton-yr exposure of IMB is 0.36±0.02(stat)±0.02(syst) as compared to an expectation of 0.51±0.01(stat)±0.05(syst). No significant dependence of this fraction on zenith angle or momentum is seen. In addition, upward-going muons from higher energy atmospheric neutrino interactions are used to search for vμ oscillations into vτ by comparing the measured rate with the expected rate from a conservative flux calculation. The ratio of upward-going muons which stop in the detector to those which exit is also used to search for deviations from the expected energy spectrum. No evidence for oscillations is found in either analysis. Finally, a search is made for an astrophysical component to the detected neutrino flux from both energetic point sources and gamma-ray bursts and also for a possible seasonal variation of the high energy neutrino flux due to atmospheric density changes. No evidence for any of these effects if found.