22 research outputs found
Search for the Proton Decay Mode proton to neutrino K+ in Soudan 2
We have searched for the proton decay mode proton to neutrino 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 mu+ nu or pi+ pi0.
We found one candidate event consistent with background, yielding a limit,
tau/B > 4.3 10^{31} years at 90% CL with no background subtraction.Comment: 13 pages, Latex, 3 tables and 3 figures, Accepted by Physics Letters
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Soudan 2 nucleon decay experiment
The Soudan 2 nucleon decay experiment consists of a 1.1 Kton fine grained iron tracking calorimeter. It has a very isotropic detection structure which along with its flexible trigger will allow detection of multiparticle and neutrino proton decay modes. The detector has now entered its construction stage
The Atmospheric neutrino flavor ratio from a 3.9 fiducial kiloton year exposure of Soudan-2
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.Comment: 15 pages, 4 figures. To be published in Physics Letters
Measurement of the atmospheric neutrino flavor composition in Soudan-2
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.Comment: 18 pages, LaTeX, 3 ps files, and 2 style files. Submitted to Physics
Letter
Observation in the MINOS far detector of the shadowing of cosmic rays by the sun and moon
The shadowing of cosmic ray primaries by the moon and sun was observed by the MINOS far detector at a depth of 2070 mwe using 83.54 million cosmic ray muons accumulated over 1857.91 live-days. The shadow of the moon was detected at the 5.6 σ level and the shadow of the sun at the 3.8 σ level using a log-likelihood search in celestial coordinates. The moon shadow was used to quantify the absolute astrophysical pointing of the detector to be 0.17 ± 0.12°. Hints of interplanetary magnetic field effects were observed in both the sun and moon shadow. © 2010 Elsevier B.V. All rights reserved
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Observation in the MINOS far detector of the shadowing of cosmic rays by the sun and moon
The shadowing of cosmic ray primaries by the moon and sun was observed by the MINOS far detector at a depth of 2070 mwe using 83.54 million cosmic ray muons accumulated over 1857.91 live-days. The shadow of the moon was detected at the 5.6 σ level and the shadow of the sun at the 3.8 σ level using a log-likelihood search in celestial coordinates. The moon shadow was used to quantify the absolute astrophysical pointing of the detector to be 0.17 ± 0.12°. Hints of interplanetary magnetic field effects were observed in both the sun and moon shadow