K. S. Ganezer

Neutrino measurements with the IMB director

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.

Limits on the flux of energetic neutrinos from the sun

Abstract A number of authors have proposed mechanisms by which the sun could be a strong source of energetic neutrinos. We search for an excess signal of penetrating neutral particles from the direction of the sun. We employ two data samples. One sample studies energies from 400 MeV to 2 GeV. The other studies v μ interactions above 2 GeV where the atmospheric background is lower. Our results are compared with the general background of atmospheric neutrinos from other directions. No significant excess has been found. These results can be used to set limits on possible dark matter candidates.

IMB-3: a large water Cherenkov detector for nucleon decay and neutrino interactions

Abstract The IMB experiment, a large water Cherenkov detector which began data collection in September 1982, has undergone several upgrades to improve light collection, on-line processing power, data throughput and buffering, calibration, and operating efficiency. The current device, known as IMB-3, enjoys a factor of four light collection advantage over its precursor. Since May 1986, it has been used to search for such diverse phenomena as nucleon decay, dark matter, neutrino oscillation, and magnetic monopoles, and to study stellar collapse and cosmic rays. Due to its large size and long exposure time IMB presents unique challenges. The design and operation of the IMB-3 detector are described in detail.

Search for Proton Decay via

We have searched for proton decay via p→νK+ using Super-Kamiokande data from April 1996 to February 2013, 260 kiloton•year exposure in total. No evidence for this proton decay mode is found. A lower limit of the proton lifetime is set to τ/B(p→νK+)>5.9×1033 years at 90% confidence level.

p \rightarrow \nu K^{+}

Abstract A device has been developed which is capable of doubling the light collection capability of a 5 inch hemispherical photomultiplier tube. Known as a “waveshifter plate”, its geometry is adaptable to various applications. Its marginal cost is small with respect to that of a phototube, it is readily removable, and it has minimum effect upon dark noise and timing resolution.

using 260 kiloton

Abstract We study the effect of matter enhanced neutrino oscillations on atmospheric neutrinos. A recently proposed solution to the solar neutrino problem with Δm 2 = 1.1×10 −4 eV 2 suggests enhanced effects in the range 200 MeV-500MeV. We find no evidence of this effect for v μ ↔ v e mixing. Limits are set on the magnitude of the mixing angle. Our limit is sin θ v

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Results from the IMB collabration to detect possible proton decay in a salt mine near Cleveland, Ohio are presented. Detection apparatus is described.(AIP)

year data of Super-Kamiokande

報告番号: 乙14530 ; 学位授与年月日: 2000-01-24 ; 学位の種別: 論文博士 ; 学位の種類: 博士(理学) ; 学位記番号: 第14530号 ; 研究科・専攻: 理学系研究科We have searched for proton decay via p{r_arrow}e{sup +}{pi}{sup 0} using data from a 25.5 kton{center_dot}yr exposure of the Super-Kamiokande detector. We find no candidate events with an expected background induced by atmospheric neutrinos of 0.1thinspthinspevents. From these data, we set a lower limit on the partial lifetime of the proton {tau}/B{sub p{r_arrow}e{sup +}{pi}{sup 0}} to be 1.6{times}10{sup 33} years at a 90{percent} confidence level. {copyright} {ital 1998} {ital The American Physical Society }