70 research outputs found
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TAO Conceptual Design Report: A Precision Measurement of the Reactor Antineutrino Spectrum with Sub-percent Energy Resolution
The Taishan Antineutrino Observatory (TAO, also known as JUNO-TAO) is a
satellite experiment of the Jiangmen Underground Neutrino Observatory (JUNO). A
ton-level liquid scintillator detector will be placed at about 30 m from a core
of the Taishan Nuclear Power Plant. The reactor antineutrino spectrum will be
measured with sub-percent energy resolution, to provide a reference spectrum
for future reactor neutrino experiments, and to provide a benchmark measurement
to test nuclear databases. A spherical acrylic vessel containing 2.8 ton
gadolinium-doped liquid scintillator will be viewed by 10 m^2 Silicon
Photomultipliers (SiPMs) of >50% photon detection efficiency with almost full
coverage. The photoelectron yield is about 4500 per MeV, an order higher than
any existing large-scale liquid scintillator detectors. The detector operates
at -50 degree C to lower the dark noise of SiPMs to an acceptable level. The
detector will measure about 2000 reactor antineutrinos per day, and is designed
to be well shielded from cosmogenic backgrounds and ambient radioactivities to
have about 10% background-to-signal ratio. The experiment is expected to start
operation in 2022
Potential of Core-Collapse Supernova Neutrino Detection at JUNO
JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve
Detection of the Diffuse Supernova Neutrino Background with JUNO
As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO
Real-time Monitoring for the Next Core-Collapse Supernova in JUNO
Core-collapse supernova (CCSN) is one of the most energetic astrophysical
events in the Universe. The early and prompt detection of neutrinos before
(pre-SN) and during the SN burst is a unique opportunity to realize the
multi-messenger observation of the CCSN events. In this work, we describe the
monitoring concept and present the sensitivity of the system to the pre-SN and
SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is
a 20 kton liquid scintillator detector under construction in South China. The
real-time monitoring system is designed with both the prompt monitors on the
electronic board and online monitors at the data acquisition stage, in order to
ensure both the alert speed and alert coverage of progenitor stars. By assuming
a false alert rate of 1 per year, this monitoring system can be sensitive to
the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos
up to about 370 (360) kpc for a progenitor mass of 30 for the case
of normal (inverted) mass ordering. The pointing ability of the CCSN is
evaluated by using the accumulated event anisotropy of the inverse beta decay
interactions from pre-SN or SN neutrinos, which, along with the early alert,
can play important roles for the followup multi-messenger observations of the
next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure
Effect of Seed Spaceflight Storage on Tomato Fruit Quality and Peel/Pulp Mineral and Antioxidant Distribution
The spaceflight storage of seeds is known to cause mutations affecting both their quality and the mature plants originating from them. To study the effects of space stress, tomato seeds of two cultivars (Lotus and Autumn rhapsody) were subjected to half a year of storage at the International Space Station (ISS), and then, sown in a greenhouse to produce tomato fruits. The space-treated plants gave smaller fruits with a stable total yield not significantly different from that of the control plants. Space-treated tomatoes showed significantly higher levels of dry matter, dietary fiber, monosaccharides and citric and malic acids and lower values of oxalic acid compared to the control plants. The pulp of space-treated fruits had 1.44–1.70 times lower levels of carotenoids, while their peel contained a 1.27–1.90 times higher pigment amount compared to the control plants. No significant changes in the total antioxidant activity (AOA), photosynthetic pigments and phenolic (TP) and proline content were recorded in the fruits due to seed spaceflight storage. Contrarily, space-treated tomatoes showed decreased levels of Ca, Sr and Mo and increased Se both in the fruit pulp and peel. The concentration of Fe and especially Pb was lower in space-treated fruit pulp. Positive correlations between Se and dry matter, Ca and Sr, Ca and Co, Ca and Fe, and Cr and carotenoids, and negative correlations between Se and Mo, Se and K, and Mo and dry matter were recorded. The results indicate that seed stress caused by long-term spaceflight affects both the biochemical characteristics and mineral composition of tomato fruits and causes the peel/pulp redistribution of carotenoids as well as macro- and micro-elements, improving Se accumulation levels in the fruit peel
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JUNO Physics and Detector
The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton LS detector
at 700-m underground. An excellent energy resolution and a large fiducial
volume offer exciting opportunities for addressing many important topics in
neutrino and astro-particle physics. With 6 years of data, the neutrino mass
ordering can be determined at 3-4 sigma and three oscillation parameters can be
measured to a precision of 0.6% or better by detecting reactor antineutrinos.
With 10 years of data, DSNB could be observed at 3-sigma; a lower limit of the
proton lifetime of 8.34e33 years (90% C.L.) can be set by searching for
p->nu_bar K^+; detection of solar neutrinos would shed new light on the solar
metallicity problem and examine the vacuum-matter transition region. A
core-collapse supernova at 10 kpc would lead to ~5000 IBD and ~2000 (300)
all-flavor neutrino-proton (electron) scattering events. Geo-neutrinos can be
detected with a rate of ~400 events/year. We also summarize the final design of
the JUNO detector and the key R&D achievements. All 20-inch PMTs have been
tested. The average photon detection efficiency is 28.9% for the 15,000 MCP
PMTs and 28.1% for the 5,000 dynode PMTs, higher than the JUNO requirement of
27%. Together with the >20 m attenuation length of LS, we expect a yield of
1345 p.e. per MeV and an effective energy resolution of 3.02%/\sqrt{E (MeV)}$
in simulations. The underwater electronics is designed to have a loss rate
<0.5% in 6 years. With degassing membranes and a micro-bubble system, the radon
concentration in the 35-kton water pool could be lowered to <10 mBq/m^3.
Acrylic panels of radiopurity <0.5 ppt U/Th are produced. The 20-kton LS will
be purified onsite. Singles in the fiducial volume can be controlled to ~10 Hz.
The JUNO experiment also features a double calorimeter system with 25,600
3-inch PMTs, a LS testing facility OSIRIS, and a near detector TAO
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TAO Conceptual Design Report: A Precision Measurement of the Reactor Antineutrino Spectrum with Sub-percent Energy Resolution
The Taishan Antineutrino Observatory (TAO, also known as JUNO-TAO) is a
satellite experiment of the Jiangmen Underground Neutrino Observatory (JUNO). A
ton-level liquid scintillator detector will be placed at about 30 m from a core
of the Taishan Nuclear Power Plant. The reactor antineutrino spectrum will be
measured with sub-percent energy resolution, to provide a reference spectrum
for future reactor neutrino experiments, and to provide a benchmark measurement
to test nuclear databases. A spherical acrylic vessel containing 2.8 ton
gadolinium-doped liquid scintillator will be viewed by 10 m^2 Silicon
Photomultipliers (SiPMs) of >50% photon detection efficiency with almost full
coverage. The photoelectron yield is about 4500 per MeV, an order higher than
any existing large-scale liquid scintillator detectors. The detector operates
at -50 degree C to lower the dark noise of SiPMs to an acceptable level. The
detector will measure about 2000 reactor antineutrinos per day, and is designed
to be well shielded from cosmogenic backgrounds and ambient radioactivities to
have about 10% background-to-signal ratio. The experiment is expected to start
operation in 2022
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The Design and Sensitivity of JUNO's scintillator radiopurity pre-detector OSIRIS
The OSIRIS detector is a subsystem of the liquid scintillator fillling chain
of the JUNO reactor neutrino experiment. Its purpose is to validate the
radiopurity of the scintillator to assure that all components of the JUNO
scintillator system work to specifications and only neutrino-grade scintillator
is filled into the JUNO Central Detector. The aspired sensitivity level of
g/g of U and Th requires a large (20 m)
detection volume and ultralow background levels. The present paper reports on
the design and major components of the OSIRIS detector, the detector simulation
as well as the measuring strategies foreseen and the sensitivity levels to U/Th
that can be reached in this setup
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JUNO sensitivity to low energy atmospheric neutrino spectra
Atmospheric neutrinos are one of the most relevant natural neutrino sources
that can be exploited to infer properties about cosmic rays and neutrino
oscillations. The Jiangmen Underground Neutrino Observatory (JUNO) experiment,
a 20 kton liquid scintillator detector with excellent energy resolution is
currently under construction in China. JUNO will be able to detect several
atmospheric neutrinos per day given the large volume. A study on the JUNO
detection and reconstruction capabilities of atmospheric and
fluxes is presented in this paper. In this study, a sample of atmospheric
neutrino Monte Carlo events has been generated, starting from theoretical
models, and then processed by the detector simulation. The excellent timing
resolution of the 3'' PMT light detection system of JUNO detector and the much
higher light yield for scintillation over Cherenkov allow to measure the time
structure of the scintillation light with very high precision. Since
and interactions produce a slightly different light pattern, the
different time evolution of light allows to discriminate the flavor of primary
neutrinos. A probabilistic unfolding method has been used, in order to infer
the primary neutrino energy spectrum from the detector experimental
observables. The simulated spectrum has been reconstructed between 100 MeV and
10 GeV, showing a great potential of the detector in the atmospheric low energy
region
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JUNO Physics Prospects
JUNO is a multipurpose underground neutrino observatory being constructed in the south of China. The main detector, with a 20 kton liquid scintillator target instrumented with about 18k 20" PMT and about 26k 3" PMT, will be strategically located 53 km from the Taishan and Yangjiang Nuclear Power Plants. Using reactor antineutrinos, JUNO will be able to measure several neutrino oscillation parameters with sub-percent precision as well as to determine the neutrino mass ordering to ∼3 over 6 years of operation. Furthermore, JUNO will have a broad physics program, ranging from studying neutrinos from other sources, such as solar and supernova neutrinos, to searching for BSM physics such as proton decay. This talk will give an overview on the JUNO's broad physics potential
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