38 research outputs found
Simulation of the Background from CO Reaction in the JUNO Scintillator
No full textInternational audienceLarge-scale organic liquid scintillator detectors are highly efficient in the detection of MeV-scale electron antineutrinos. These signal events can be detected through inverse beta decay on protons, which produce a positron accompanied by a neutron. A noteworthy background for antineutrinos coming from nuclear power reactors and from the depths of the Earth (geoneutrinos) is generated by () reactions. In organic liquid scintillator detectors, particles emitted from intrinsic contaminants such as U, Th, and Pb/Po, can be captured on C nuclei, followed by the emission of a MeV-scale neutron. Three distinct interaction mechanisms can produce prompt energy depositions preceding the delayed neutron capture, leading to a pair of events correlated in space and time within the detector. Thus, () reactions represent an indistinguishable background in liquid scintillator-based antineutrino detectors, where their expected rate and energy spectrum are typically evaluated via Monte Carlo simulations. This work presents results from the open-source SaG4n software, used to calculate the expected energy depositions from the neutron and any associated de-excitation products. Also simulated is a detailed detector response to these interactions, using a dedicated Geant4-based simulation software from the JUNO experiment. An expected measurable CO event rate and reconstructed prompt energy spectrum with associated uncertainties, are presented in the context of JUNO, however, the methods and results are applicable and relevant to other organic liquid scintillator neutrino detectors
JUNO Sensitivity on Proton Decay Searches
No full textThe Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid
scintillator detector designed to explore many topics in fundamental physics.
In this paper, the potential on searching for proton decay in mode with JUNO is investigated.The kaon and its decay particles feature a
clear three-fold coincidence signature that results in a high efficiency for
identification. Moreover, the excellent energy resolution of JUNO permits to
suppress the sizable background caused by other delayed signals. Based on these
advantages, the detection efficiency for the proton decay via is 36.9% with a background level of 0.2 events after 10 years of data
taking. The estimated sensitivity based on 200 kton-years exposure is years, competitive with the current best limits on the proton
lifetime in this channel.Comment: 14 pages, 12 figures, an author adde
JUNO Sensitivity to Invisible Decay Modes of Neutrons
No full textInternational audienceWe explore the bound neutrons decay into invisible particles (e.g., or ) in the JUNO liquid scintillator detector. The invisible decay includes two decay modes: and . The invisible decays of -shell neutrons in will leave a highly excited residual nucleus. Subsequently, some de-excitation modes of the excited residual nuclei can produce a time- and space-correlated triple coincidence signal in the JUNO detector. Based on a full Monte Carlo simulation informed with the latest available data, we estimate all backgrounds, including inverse beta decay events of the reactor antineutrino , natural radioactivity, cosmogenic isotopes and neutral current interactions of atmospheric neutrinos. Pulse shape discrimination and multivariate analysis techniques are employed to further suppress backgrounds. With two years of exposure, JUNO is expected to give an order of magnitude improvement compared to the current best limits. After 10 years of data taking, the JUNO expected sensitivities at a 90% confidence level are and
JUNO Sensitivity to Invisible Decay Modes of Neutrons
No full textWe explore the bound neutrons decay into invisible particles (e.g., or ) in the JUNO liquid scintillator detector. The invisible decay includes two decay modes: and . The invisible decays of -shell neutrons in will leave a highly excited residual nucleus. Subsequently, some de-excitation modes of the excited residual nuclei can produce a time- and space-correlated triple coincidence signal in the JUNO detector. Based on a full Monte Carlo simulation informed with the latest available data, we estimate all backgrounds, including inverse beta decay events of the reactor antineutrino , natural radioactivity, cosmogenic isotopes and neutral current interactions of atmospheric neutrinos. Pulse shape discrimination and multivariate analysis techniques are employed to further suppress backgrounds. With two years of exposure, JUNO is expected to give an order of magnitude improvement compared to the current best limits. After 10 years of data taking, the JUNO expected sensitivities at a 90% confidence level are and
JUNO Sensitivity to Invisible Decay Modes of Neutrons
No full textWe explore the bound neutrons decay into invisible particles (e.g.,
or ) in the JUNO liquid scintillator
detector. The invisible decay includes two decay modes: and . The invisible decays of -shell neutrons in
will leave a highly excited residual nucleus. Subsequently, some
de-excitation modes of the excited residual nuclei can produce a time- and
space-correlated triple coincidence signal in the JUNO detector. Based on a
full Monte Carlo simulation informed with the latest available data, we
estimate all backgrounds, including inverse beta decay events of the reactor
antineutrino , natural radioactivity, cosmogenic isotopes and
neutral current interactions of atmospheric neutrinos. Pulse shape
discrimination and multivariate analysis techniques are employed to further
suppress backgrounds. With two years of exposure, JUNO is expected to give an
order of magnitude improvement compared to the current best limits. After 10
years of data taking, the JUNO expected sensitivities at a 90% confidence level
are and
.Comment: 28 pages, 7 figures, 4 table
JUNO Sensitivity to Invisible Decay Modes of Neutrons
No full textInternational audienceWe explore the bound neutrons decay into invisible particles (e.g., or ) in the JUNO liquid scintillator detector. The invisible decay includes two decay modes: and . The invisible decays of -shell neutrons in will leave a highly excited residual nucleus. Subsequently, some de-excitation modes of the excited residual nuclei can produce a time- and space-correlated triple coincidence signal in the JUNO detector. Based on a full Monte Carlo simulation informed with the latest available data, we estimate all backgrounds, including inverse beta decay events of the reactor antineutrino , natural radioactivity, cosmogenic isotopes and neutral current interactions of atmospheric neutrinos. Pulse shape discrimination and multivariate analysis techniques are employed to further suppress backgrounds. With two years of exposure, JUNO is expected to give an order of magnitude improvement compared to the current best limits. After 10 years of data taking, the JUNO expected sensitivities at a 90% confidence level are and
JUNO physics and detector
No full textThe Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton liquid scintillator detector in a laboratory 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 six years of data, the neutrino mass ordering can be determined at a 3-4 sigma significance and the neutrino oscillation parameters sin(2 )theta(12), Delta m(21)(2), and vertical bar Delta m(32)(2)vertical bar can be measured to a precision of 0.6% or better, by detecting reactor antineutrinos from the Taishan and Yangjiang nuclear power plants. With ten years of data, neutrinos from all past core-collapse supernovae could be observed at a 3 sigma significance; a lower limit of the proton lifetime, 8.34 x 10(33) years (90% C.L.), can be set by searching for p -> (nu) over barK(+); detection of solar neutrinos would shed new light on the solar metallicity problem and examine the vacuum-matter transition region. A typical core-collapse supernova at a distance of 10 kpc would lead to similar to 5000 inverse-beta-decay events and similar to 2000 (300) all-flavor neutrino-proton (electron) elastic scattering events in JUNO. Geo-neutrinos can be detected with a rate of similar to 400 events per year. Construction of the detector is very challenging. In this review, we summarize the final design of the JUNO detector and the key R&D achievements, following the Conceptual Design Report in 2015 (Djurcic et al., 2015). All 20-inch PMTS have been procured and tested. The average photon detection efficiency is 28.9% for the 15,000 MCP PMTS and 28.1% for the 5000 dynode PMTS, higher than the JUNO requirement of 27%. Together with the >20 m attenuation length of the liquid scintillator achieved in a 20-ton pilot purification test and the >96% transparency of the acrylic panel, we expect a yield of 1345 photoelectrons per MeV and an effective relative energy resolution of 3.02%/root E(MeV) in simulations (Abusleme et al., 2021). To maintain the high performance, the underwater electronics is designed to have a loss rate <0.5% in six 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 for the 35.4-m diameter liquid scintillator vessel are produced with a dedicated production line. The 20 kton liquid scintillator will be purified onsite with Alumina filtration, distillation, water extraction, and gas stripping. Together with other low background handling, singles in the fiducial volume can be controlled to similar to 10 Hz. The JUNO experiment also features a double calorimeter system with 25,600 3-inch PMTS, a liquid scintillator testing facility OSIRIS, and a near detector TAO. (JUNO Collaboration
JUNO Physics Prospects
No full textJUNO is a multi-purpose 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 σ 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
The design and sensitivity of JUNO’s scintillator radiopurity pre-detector OSIRIS
No full textThe OSIRIS detector is a subsystem of the liquid scintillator filling 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 10-16g/g of 238U and 232Th requires a large (∼20m3) 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
Detection of the diffuse supernova neutrino background with JUNO
No full textAs 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 in 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
