68 research outputs found
Large photocathode 20-inch PMT testing at the scanning station for the JUNO experiment
No full textThe 20kt Liquid Scintillator (LS) JUNO detector is being constructed by the International Collaboration in China. The primary goal of JUNO is the neutrino mass ordering determination. The main challenge for JUNO is to achieve an unprecedented energy resolution, ~3% at 1 MeV of energy released in the LS. About 20000 large 20'' PMTs with high Photon Detection Efficiency (PDE) will cover the detector surface. High demands on the energy resolution place distinct requirements to PMTs properties, namely high uniformity of PDE and gain along the photocathode surface. A dedicated scanning system was constructed for PMTs tests that allows us to study the variation of the abovementioned characteristics. It allows for the testing of individual PMTs in all relevant aspects by means of scanning the photocathode and identifying any potential problems. The scanning setup, method and results of PMTs performance tests are reported
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
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 {\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
Feasibility of detecting B8 solar neutrinos at JUNO
No full textThe Jiangmen Underground Neutrino Observatory (JUNO) features a 20 kt multi-purpose underground
liquid scintillator sphere as its main detector. In this talk we describe in detail a comprehensive assessment of JUNO's potential for detecting 8B solar neutrinos via the neutrino-electron elastic scattering process. A reduced 2 MeV threshold for the recoil electron energy is achievable with optimized background reduction strategies. With ten years of data taking, about 60,000 signal and 30,000 background events are expected. This leads to a simultaneous measurement of sin2θ12 and Δm221 using reactor antineutrinos and solar neutrinos in the JUNO detector. This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter. If Δm221=4.8×10−5(7.5×10−5eV2), JUNO can provide evidence of neutrino oscillation in the Earth at approximately the 3σ (2σ) level by measuring the non-zero signal rate variation with respect to the solar zenith angle. Moreover, JUNO can simultaneously measure Δm221 using 8B solar neutrinos to a precision of 20% or better, depending on the central value, and to sub-percent precision using reactor antineutrinos. A comparison of these two measurements from the same detector will help understand the current mild inconsistency between the value of reported by solar neutrino experiments and the KamLAND experiment
Potential of Core-Collapse Supernova Neutrino Detection at JUNO
No full textJUNO 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
Final COMPASS Results on the Transverse-Spin-Dependent Azimuthal Asymmetries in the Pion-Induced Drell-Yan Process
No full textThe COMPASS Collaboration performed measurements of the Drell-Yan process in 2015 and 2018 using a 190 GeV/c π- beam impinging on a transversely polarized ammonia target. Combining the data of both years, we present final results on the amplitudes of five azimuthal modulations, which correspond to transverse-spin-dependent azimuthal asymmetries (TSAs) in the dimuon production cross section. Three of them probe the nucleon leading-twist Sivers, transversity, and pretzelosity transverse-momentum dependent (TMD) parton distribution functions (PDFs). The other two are induced by subleading effects. These TSAs provide unique new inputs for the study of the nucleon TMD PDFs and their universality properties. In particular, the Sivers TSA observed in this measurement is consistent with the fundamental QCD prediction of a sign change of naive time-reversal-odd TMD PDFs when comparing the Drell-Yan process with deep inelastic scattering. Also, within the context of model predictions, the observed transversity TSA is consistent with the expectation of a sign change for the Boer-Mulders function
JUNO sensitivity to Be, , and CNO solar neutrinos
No full textInternational audienceThe Jiangmen Underground Neutrino Observatory (JUNO), the first multi-kton liquid scintillator detector, which is under construction in China, will have a unique potential to perform a real-time measurement of solar neutrinos well below the few MeV threshold typical for Water Cherenkov detectors. JUNO's large target mass and excellent energy resolution are prerequisites for reaching unprecedented levels of precision. In this paper, we provide estimation of the JUNO sensitivity to 7Be, pep, and CNO solar neutrinos that can be obtained via a spectral analysis above the 0.45 MeV threshold. This study is performed assuming different scenarios of the liquid scintillator radiopurity, ranging from the most opti mistic one corresponding to the radiopurity levels obtained by the Borexino experiment, up to the minimum requirements needed to perform the neutrino mass ordering determination with reactor antineutrinos - the main goal of JUNO. Our study shows that in most scenarios, JUNO will be able to improve the current best measurements on 7Be, pep, and CNO solar neutrino fluxes. We also perform a study on the JUNO capability to detect periodical time variations in the solar neutrino flux, such as the day-night modulation induced by neutrino flavor regeneration in Earth, and the modulations induced by temperature changes driven by helioseismic waves
Transverse-spin-dependent azimuthal asymmetries of pion and kaon pairs produced in muon-proton and muon-deuteron semi-inclusive deep inelastic scattering
No full textA set of measurements of azimuthal asymmetries in the production of pairs of identified hadrons in deep-inelastic scattering of muons on transversely polarised <sup>6</sup>LiD (deuteron) and NH3 (proton) targets is presented. All available data collected in the years 2003–2004 and 2007/2010 with the COMPASS spectrometer using a muon beam of 160GeV/c at the CERN SPS were analysed. The asymmetries provide access to the transversity distribution functions via a fragmentation function that in principle may be independently obtained from e+e− annihilation data. Results are presented, discussed and compared to existing measurements as well as to model predictions. Asymmetries of π+π− pairs measured with the proton target as a function of the Bjorken scaling variable are sizeable in the range x>0.032, indicating non-vanishing transversity distribution and di-hadron interference fragmentation functions. As already pointed out by several authors, the small asymmetries of π+π− measured on the <sup>6</sup>LiD target can be interpreted as indication for a cancellation of u and d-quark transversity distributions
The JUNO experiment Top Tracker
No full textThe main task of the Top Tracker detector of the neutrino reactor experiment
Jiangmen Underground Neutrino Observatory (JUNO) is to reconstruct and
extrapolate atmospheric muon tracks down to the central detector. This muon
tracker will help to evaluate the contribution of the cosmogenic background to
the signal. The Top Tracker is located above JUNO's water Cherenkov Detector
and Central Detector, covering about 60% of the surface above them. The JUNO
Top Tracker is constituted by the decommissioned OPERA experiment Target
Tracker modules. The technology used consists in walls of two planes of plastic
scintillator strips, one per transverse direction. Wavelength shifting fibres
collect the light signal emitted by the scintillator strips and guide it to
both ends where it is read by multianode photomultiplier tubes. Compared to the
OPERA Target Tracker, the JUNO Top Tracker uses new electronics able to cope
with the high rate produced by the high rock radioactivity compared to the one
in Gran Sasso underground laboratory. This paper will present the new
electronics and mechanical structure developed for the Top Tracker of JUNO
along with its expected performance based on the current detector simulation.Comment: 20 page
High-Statistics Measurement of Collins and Sivers Asymmetries for Transversely Polarized Deuterons
No full textNew results are presented on a high-statistics measurement of Collins and Sivers asymmetries of charged hadrons produced in deep inelastic scattering of muons on a transversely polarized LiD6 target. The data were taken in 2022 with the COMPASS spectrometer using the 160 GeV muon beam at CERN, statistically balancing the existing data on transversely polarized proton targets. The first results from about two-thirds of the new data have total uncertainties smaller by up to a factor of three compared to the previous deuteron measurements. Using all the COMPASS proton and deuteron results, both the transversity and the Sivers distribution functions of the u and d quark, as well as the tensor charge in the measured x range are extracted. In particular, the accuracy of the d quark results is significantly improved
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