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Creators/Authors contains: "Kotera, K"

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  1. ; ; ; ; ; ; ; ; ; ; et al (, Astrophysical journal)
    Abstract The electron antineutrino flux limits are presented for the brightest gamma-ray burst (GRB) of all time, GRB221009A, over a range of 1.8–200 MeV using the Kamioka Liquid Scintillator Antineutrino Detector. Using multiple time windows ranging from minutes to days surrounding the event to search for electron antineutrinos coincident with the GRB, we set an upper limit on the flux under the assumption of several power-law neutrino source spectra, with power-law indices ranging from 1.5 to 3 in steps of 0.5. No excess was observed in any time windows ranging from seconds to days around the event trigger timeT0. For a power-law index of 2 and a time window ofT0 ±  500 s, a flux upper limit of 2.34  ×  109cm−2was calculated. The limits are compared to the results presented by IceCube. 
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    Free, publicly-accessible full text available March 7, 2026
  2. ; ; ; ; ; ; ; ; ; ; et al (, Physics Letters B)
    Particle dark matter could belong to a multiplet that includes an electrically charged state. WIMP dark matter (χ0) accompanied by a negatively charged excited state (χ−) with a small mass difference (e.g. < 20 MeV) can form a bound-state with a nucleus such as xenon. This bound-state formation is rare and the released energy is O(1−10) MeV depending on the nucleus, making large liquid scintillator detectors suitable for detection. We searched for bound-state formation events with xenon in two experimental phases of the KamLAND-Zen experiment, a xenon-doped liquid scintillator detector. No statistically significant events were observed. For a benchmark parameter set of WIMP mass mχ0=1 TeV and mass difference Δm=17 MeV, we set the most stringent upper limits on the recombination cross section times velocity 〈σv〉 and the decay-width of χ− to 9.2×10−30cm3/s and 8.7×10−14 GeV, respectively at 90% confidence level. 
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  3. ; ; ; ; (, Journal of cosmology and astroparticle physics)
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  4. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review C)
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  5. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review D)
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  6. ; ; ; ; ; ; ; ; ; ; et al (, Sissa Medialab)
  7. ; ; ; ; ; ; ; ; ; ; et al (, Astroparticle Physics)
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  8. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review Letters)
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  9. ; ; ; ; ; ; ; ; ; ; et al (, Astroparticle Physics)
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  10. ; ; ; ; ; ; ; ; ; ; et al (, The Astrophysical Journal)
    Abstract We present the results of a search for core-collapse supernova neutrinos, using long-term KamLAND data from 2002 March 9 to 2020 April 25. We focus on the electron antineutrinos emitted from supernovae in the energy range of 1.8–111 MeV. Supernovae will make a neutrino event cluster with the duration of ∼10 s in the KamLAND data. We find no neutrino clusters and give the upper limit on the supernova rate to be 0.15 yr−1with a 90% confidence level. The detectable range, which corresponds to a >95% detection probability, is 40–59 kpc and 65–81 kpc for core-collapse supernovae and failed core-collapse supernovae, respectively. This paper proposes to convert the supernova rate obtained by the neutrino observation to the Galactic star formation rate. Assuming a modified Salpeter-type initial mass function, the upper limit on the Galactic star formation rate is <(17.5–22.7)M⊙yr−1with a 90% confidence level. 
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