Wade De La

Abstract:

A search for nucleon decay into two-body final states containing K0 mesons has been conducted using the 963 metric ton Soudan 2 iron tracking calorimeter. The topologies, ionizations, and kinematics of contained events recorded in a 5.52 kiloton-year total exposure (4.41 kton-year fiducial volume exposure) are examined for compatibility with nucleon decays in an iron medium. For proton decay into the fully visible final states μ+KS0 and e+KS0, zero and one event candidates are observed respectively. The lifetime lower limits (τ/B) thus implied are 1.5×1032 yr and 1.2×1032 yr, respectively. Lifetime lower limits are also reported for proton decay into l+K10, and for neutron decay into vKS0. ©2000 The American Physical Society.

Abstract:

A shadow of the Moon, with a statistical significance of (Formula presented) has been observed in the underground muon flux at a depth of 2090 mwe using the Soudan 2 detector. The angular resolution of the detector is well described by a Gaussian with a sigma (Formula presented) The position of the shadow confirms that the alignment of the detector is known to better than (Formula presented) and has remained stable during ten years of data taking. © 2000 The American Physical Society.

Abstract:

We report a measurement of the atmospheric neutrino flavor ratio, R, using a sample of quasi-elastic neutrino interactions occurring in an iron medium. The flavor ratio (tracks/showers) of atmospheric neutrinos in a 3.9 fiducial kiloton-year exposure of Soudan 2 is 0.64 ± 0.11(stat.) ± 0.06(syst.) of that expected. Important aspects of our main analysis have been checked by carrying out two independent, alternative analyses; one is based upon automated scanning, the other uses a multivariate approach for background subtraction. Similar results are found by all three approaches. © 1999 Elsevier Science B.V. All rights reserved.

Abstract:

We have searched for the proton decay mode p → ν K+ using the one-kiloton Soudan 2 high resolution calorimeter. Contained events obtained from a 3.56 kiloton-year fiducial exposure through June 1997 are examined for occurrence of a visible K+ track which decays at rest into μ+ ν or π+ π0. We found one candidate event consistent with background, yielding a limit, τ/B(p → ν K+) > 4.3 × 1031 years at 90% CL with no background subtraction. © 1998 Published by Elsevier Science B.V. All rights reserved.

Abstract:

The atmospheric neutrino flavour ratio measured using a 1.52 kton-year exposure of Soudan 2 is found to be 0.72 ± 0.19+0.05-0.07 relative to the expected value from a Monte Carlo calculation. The possible background of interactions of neutrons and photons produced in muon interactions in the rock surrounding the detector has been investigated and is shown not to produce low values of the ratio.