A search for Supernova Relic Neutrinos ν¯e’s is first conducted via inverse-beta-decay by tagging neutron capture on hydrogen at Super-Kamiokande-IV. The neutron tagging efficiency is determined to ...be (17.74±0.04stat.±1.05sys.)%, while the corresponding accidental background probability is (1.06±0.01stat.±0.18sys.)%. Using 960days of data, we obtain 13 inverse-beta-decay candidates in the range of Eν¯e between 13.3MeV and 31.3MeV. All of the observed candidates are attributed to background. Upper limits at 90% C.L. are calculated in the absence of a signal.
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The MTV (
M
ott Polarimetry for
T
-
V
iolation Experiment) experiment at TRIUMF-ISAC (
I
sotope
S
eparator and
AC
celerator), which aims to achieve the highest precision test of time reversal ...symmetry in polarized nuclear beta decay by measuring a triple correlation (
R
-correlation), is motivated by the search for a new physics beyond the Standard Model. In this experiment, the existence of non-zero transverse electron polarization is examined utilizing the analyzing power of Mott scattering from a thin metal foil. Backward scattering electron tracks are measured using a multi-wire drift chamber for the first time. The MTV experiment was commissioned at ISAC in 2009 using an 80 % polarized
8
Li beam at 10
7
pps, resulting in 0.1 % statistical precision on the
R
-parameter in the first physics run performed in 2010. Next generation cylindrical drift chamber (CDC) is now being installed for the future run.
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33.
Calibration of the Super-Kamiokande detector Abe, K.; Iyogi, K.; Kameda, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2014, Volume:
737
Journal Article
Peer reviewed
Open access
Procedures and results on hardware-level detector calibration in Super-Kamiokande (SK) are presented in this paper. In particular, we report improvements made in our calibration methods for the ...experimental phase IV in which new readout electronics have been operating since 2008.
The topics are separated into two parts. The first part describes the determination of constants needed to interpret the digitized output of our electronics so that we can obtain physical numbers such as photon counts and their arrival times for each photomultiplier tube (PMT). In this context, we developed an in situ procedure to determine high-voltage settings for PMTs in large detectors like SK, as well as a new method for measuring PMT quantum efficiency and gain in such a detector.
The second part describes modeling of the detector in Monte Carlo simulations, including, in particular, the optical properties of the water target and their variability over time. Detailed studies on water quality are also presented.
As a result of this work, we have achieved a precision sufficient for physics analyses over a wide energy range (from a few MeV to above 1TeV). For example, charge determination was at the level of 1%, and the timing resolution was 2.1ns at the one-photoelectron charge level and 0.5ns at the 100-photoelectron charge level.
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Cosmic-ray-muon spallation-induced radioactive isotopes with beta decays are one of the major backgrounds for solar, reactor, and supernova relic neutrino experiments. Unlike in scintillator, ...production yields for cosmogenic backgrounds in water have not been exclusively measured before, yet they are becoming more and more important in next generation neutrino experiments designed to search for rare signals. We have analyzed the low-energy trigger data collected at Super-Kamiokande IV in order to determine the production rates of B super(12), N super(12), N super(16), Be super(11), Li super(9), He super(8), C super(9), Li super(8), B super(8), and C super(15). These rates were extracted from fits to time differences between parent muons and subsequent daughter beta 's by fixing the known isotope lifetimes. Since Li super(9) can fake an inverse-beta-decay reaction chain via a beta +n cascade decay, producing an irreducible background with detected energy up to a dozen MeV, a dedicated study is needed for evaluating its impact on future measurements; the application of a neutron tagging technique using correlated triggers was found to improve this Li super(9) measurement. The measured yields were generally found to be comparable with theoretical calculations, except the cases of the isotopes Li super(8)/B super(8) and Li super(9).
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We report an indication that the elastic scattering rate of solar B8 neutrinos with electrons in the Super-Kamiokande detector is larger when the neutrinos pass through Earth during nighttime. We ...determine the day-night asymmetry, defined as the difference of the average day rate and average night rate divided by the average of those two rates, to be -3.2 ± 1.1(stat) ± 0.5(syst)%, which deviates from zero by 2.7 σ. Since the elastic scattering process is mostly sensitive to electron-flavored solar neutrinos, a nonzero day-night asymmetry implies that the flavor oscillations of solar neutrinos are affected by the presence of matter within the neutrinos' flight path. Super-Kamiokande's day-night asymmetry is consistent with neutrino oscillations for 4 × 10(-5) eV(2) ≤ Δm 2(21) ≤ 7 × 10(-5) eV(2) and large mixing values of θ12, at the 68% C.L.
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Norharman (9H-pyrido3,4-bindole) and harman (1-methyl-9H-pyrido3,4-bindole) contained in cigarette smoke and cooked foodstuffs, are non-mutagenic to Salmonella strains, but show co-mutagenicity with ...S9 mixture in the presence of aniline or o-toluidine. The resulting 9-(4′-aminophenyl)-9H-pyrido3,4-bindole (aminophenylnorharman, APNH), 9-(4′-amino-3′-methylphenyl)-9H-pyrido3,4-bindole (aminomethylphenylnorharman, AMPNH) and 9-(4′-aminophenyl)-1-methyl-9H-pyrido3,4-bindole (aminophenylharman, APH) are produced by coupling of norharman and aniline, norharman and o-toluidine, and harman and aniline in the presence of S9 mixture, respectively. To clarify the role of human cytochrome P450 (P450) and N-acetyltransferase (NAT) enzymes in the metabolic activation of APNH, AMPNH and APH, we determined the genotoxicity of these coupling chemicals using a variety of umu tester strains established in our laboratories. APNH, AMPNH and APH induced umuC gene expression more strongly in a bacterial O-acetyltransferase-overproducing strain than the parent strain. These chemicals were also found to induce umuC gene expression in NAT2-overexpressing strain at much higher rate than the NAT1-overexpressing strain. Among seven OY strains expressing human P450s and NADPH-P450 reductase used, the genotoxicity of APNH, AMPNH and APH was detected in OY1002/1A2 strain, OY1002/1A1 and OY1002/1A2 strains, and in OY1002/1A2 strain, respectively. From these results, it is concluded that APNH, AMPNH and APH are mainly bioactivated by P450 1A2 and NAT2, followed by NAT1 enzymes. P450 1A1 was also found to activate AMPNH at relatively slower rates.
A neutrino burst was observed in the Kamiokande II detector on 23 February 1987, 7:35:35 UT (+ or - 1 min) during a time interval of 13 sec. The signal consisted of eleven electron events of energy ...7.5 to 36 MeV, of which the first two point back to the Large Magellanic Cloud with angles 18 deg + or - 18 deg and 15 deg + or - 27 deg. (Author)
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Super-Kamiokande atmospheric neutrino data were fit with an unbinned maximum likelihood method to search for the appearance of tau leptons resulting from the interactions of oscillation-generated tau ...neutrinos in the detector. Relative to the expectation of unity, the tau normalization is found to be 1.42 ± 0.35(stat)(-0.12)(+0.14)(syst) excluding the no-tau-appearance hypothesis, for which the normalization would be zero, at the 3.8σ level. We estimate that 180.1 ± 44.3(stat)(-15.2)(+17.8) (syst) tau leptons were produced in the 22.5 kton fiducial volume of the detector by tau neutrinos during the 2806 day running period. In future analyses, this large sample of selected tau events will allow the study of charged current tau neutrino interaction physics with oscillation produced tau neutrinos.
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