60 research outputs found
Distillation of Liquid Xenon to Remove Krypton
A high performance distillation system to remove krypton from xenon was
constructed, and a purity level of Kr/Xe = was
achieved. This development is crucial in facilitating high sensitivity low
background experiments such as the search for dark matter in the universe.Comment: 15 pages, 11 figure
Clinical disorders affecting mesopic vision
Vision in the mesopic range is affected by a number of inherited and acquired clinical disorders. We review these conditions and summarize the historical background, describing the clinical characteristics alongside the genetic basis and molecular biological mechanisms giving rise to rod and cone dysfunction relevant to twilight vision. The current diagnostic gold standards for each disease are discussed and curative and symptomatic treatment strategies are summarized
Coordinated and Cohesive Movement of Two Small Conspecific Fish Induced by Eliciting a Simultaneous Optomotor Response
BACKGROUND: In animal groups such as herds, schools, and flocks, a certain distance is maintained between adjacent individuals, allowing them to move as a cohesive unit. Proximate causations of the cohesive and coordinated movement under dynamic conditions, however, have been poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: We established a novel and simple behavioral assay using pairs of small fish (medaka and dwarf pufferfish) by eliciting a simultaneous optomotor response (OMR). We demonstrated that two homospecific fish began to move cohesively and maintained a distance of 2 to 4 cm between them when an OMR was elicited simultaneously in the fish. The coordinated and cohesive movement was not exhibited under a static condition. During the cohesive movement, the relative position of the two fish was not stable. Furthermore, adult medaka exhibited the cohesive movement but larvae did not, despite the fact that an OMR could be elicited in larvae, indicating that this ability to coordinate movement develops during maturation. The cohesive movement was detected in homospecific pairs irrespective of body-color, sex, or albino mutation, but was not detected between heterospecific pairs, suggesting that coordinated movement is based on a conspecific interaction. CONCLUSIONS/SIGNIFICANCE: Our findings demonstrate that coordinated behavior between a pair of animals was elicited by a simultaneous OMR in two small fish. This is the first report to demonstrate induction of a schooling-like movement in a pair of fish by an OMR and to investigate the effect of age, sex, body color, and species on coordination between animals under a dynamic condition
Precision Analysis of the 136Xe Two-Neutrino ββ Spectrum in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements
We present a precision analysis of the 136Xe two-neutrino ββ electron spectrum above 0.8MeV, based on high-statistics data obtained with the KamLAND-Zen experiment. An improved formalism for the two-neutrino ββ rate allows us to measure the ratio of the leading and subleading 2νββ nuclear matrix elements (NMEs), ξ2ν31 = −0.26 +0.31−0.25. Theoretical predictions from the nuclear shell model and the majority of the quasiparticle random-phase approximation (QRPA) calculations are consistent with the experimental limit. However, part of the ξ2ν31 range allowed by the QRPA is excluded by the present measurement at the 90% confidence level. Our analysis reveals that predicted ξ2ν31 values are sensitive to the quenching of NMEs and the competing contributions from low- and high-energy states in the intermediate nucleus. Because these aspects are also at play in neutrinoless ββ decay, ξ2ν31 provides new insights toward reliable neutrinoless ββ NMEs
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Search for charged excited states of dark matter with KamLAND-Zen
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 9.2×10−30 cm3/s and 8.7×10−14 GeV, respectively at 90% confidence level
Search for solar flare neutrinos with the KamLAND detector
We report the result of a search for neutrinos in coincidence with solar flares from the GOES flare database. The search was performed on a 10.8 kton-year exposure of KamLAND collected from 2002 to 2019. This large exposure allows us to explore previously unconstrained parameter space for solar flare neutrinos. We found no statistical excess of neutrinos and established 90% confidence level upper limits of 8.4 × 10^7 cm^−2 (3.0 × 10^9 cm^−2) on the electron antineutrino (electron neutrino) fluence at 20 MeV normalized to the X12 flare, assuming that the neutrino fluence is proportional to the X-ray intensity.https://arxiv.org/abs/2105.0245
First measurement of the strange axial coupling constant using neutral-current quasi-elastic interactions of atmospheric neutrinos at KamLAND
We report a measurement of the strange axial coupling constant using
atmospheric neutrino data at KamLAND. This constant is a component of the axial
form factor of the neutral current quasi-elastic (NCQE) interaction. The value
of significantly changes the ratio of proton and neutron NCQE cross
sections. KamLAND is suitable for measuring NCQE interactions as it can detect
nucleon recoils with low energy thresholds and measure neutron multiplicity
with high efficiency. KamLAND data, including the information on neutron
multiplicity associated with the NCQE interactions, makes it possible to
measure with a suppressed dependence on the axial mass , which has
not yet been determined. For a comprehensive prediction of the neutron emission
associated with neutrino interactions, we establish a simulation of particle
emission via nuclear de-excitation of C, a process not considered in
existing neutrino Monte Carlo event generators. Energy spectrum fitting for
each neutron multiplicity gives , which is the
most stringent limit obtained using NCQE interactions without
constraints
Measurement of cosmic-ray muon spallation products in a xenon-loaded liquid scintillator with KamLAND
Cosmic-ray muons produce various radioisotopes when passing through material.
These spallation products can be backgrounds for rare event searches such as in
solar neutrino, double-beta decay, and dark matter search experiments. The
KamLAND-Zen experiment searches for neutrinoless double-beta decay in 745kg of
xenon dissolved in liquid scintillator. The experiment includes dead-time-free
electronics with a high efficiency for detecting muon-induced neutrons. The
production yields of different radioisotopes are measured with a combination of
delayed coincidence techniques, newly developed muon reconstruction and xenon
spallation identification methods. The observed xenon spallation products are
consistent with results from the FLUKA and Geant4 simulation codes
KamLAND's search for correlated low-energy electron antineutrinos with astrophysical neutrinos from IceCube
We report the results of a search for MeV-scale astrophysical neutrinos in
KamLAND presented as an excess in the number of coincident neutrino
interactions associated with the publicly available high-energy neutrino
datasets from the IceCube Neutrino Observatory. We find no statistically
significant excess in the number of observed low-energy electron antineutrinos
in KamLAND, given a coincidence time window of 500s, 1,000s,
3,600s, and 10,000s around each of the IceCube neutrinos. We use this
observation to present limits from 1.8 MeV to 100 MeV on the electron
antineutrino fluence, assuming a mono-energetic flux. We then compare the
results to several astrophysical measurements performed by IceCube and place a
limit at the 90% confidence level on the electron antineutrino isotropic
thermal luminosity from the TXS 0506+056 blazar.Comment: 12 pages, 5 figure
Mate-guarding behavior enhances male reproductive success via familiarization with mating partners in medaka fish
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