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Final assessment of radioactive impurities in the JUNO detector
Authors:
Thomas Adam,
Fengpeng An,
Costas Andreopoulos,
Giuseppe Andronico,
Nikolay Anfimov,
Vito Antonelli,
Tatiana Antoshkina,
João Pedro Athayde Marcondes de André,
Didier Auguste,
Nikita Balashov,
Andrea Barresi,
Davide Basilico,
Eric Baussan,
Marco Beretta,
Antonio Bergnoli,
Nikita Bessonov,
Daniel Bick,
Lukas Bieger,
Svetlana Biktemerova,
Thilo Birkenfeld,
Simon Blyth,
Manuel Böhles,
Anastasia Bolshakova,
Mathieu Bongrand,
Matteo Borghesi
, et al. (549 additional authors not shown)
Abstract:
The Jiangmen Underground Neutrino Observatory (JUNO) collaboration has completed the construction of the 20,000-ton liquid scintillator detector and the associated muon veto detector system. To meet the physics objectives, the materials used in the detector must exhibit low radioactive contamination. The single-event rate in the fiducial volume (R $<$ 17.2 m) of the scintillator is required to be…
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The Jiangmen Underground Neutrino Observatory (JUNO) collaboration has completed the construction of the 20,000-ton liquid scintillator detector and the associated muon veto detector system. To meet the physics objectives, the materials used in the detector must exhibit low radioactive contamination. The single-event rate in the fiducial volume (R $<$ 17.2 m) of the scintillator is required to be approximately 7 Hz for energies above 0.7 MeV, resulting in an accidental coincidence background of about 1 event per day for reactor neutrino physics analyses. Since the beginning of the construction phase, we have screened the natural radioactivity content of thousands of materials, to select those that meet the design background budget. The radioactive impurity concentrations of the materials ultimately used in the JUNO detector are summarized in this paper. The construction of the entire detector and the subsequent filling of the liquid scintillator were completed in August 2025. From the initial data, the total count rate of natural radioactivity within the detector's fiducial volume has met the requirements and is sufficient to support the reactor antineutrino analysis.
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Submitted 19 July, 2026;
originally announced July 2026.
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Trends, Volatility, Correlations, and Critical Phenomena in Financial Markets
Authors:
Sara A. Safari,
Christoph Schmidhuber
Abstract:
We forecast future volatilities and correlations of financial markets based on the current trends in these markets. This complements previous work that models future expected returns by a cubic polynomial of the current trend strength. Empirically, we observe that volatilities and correlations tend to increase day after day in times of strong up- or down-trends. This effect is particularly pronoun…
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We forecast future volatilities and correlations of financial markets based on the current trends in these markets. This complements previous work that models future expected returns by a cubic polynomial of the current trend strength. Empirically, we observe that volatilities and correlations tend to increase day after day in times of strong up- or down-trends. This effect is particularly pronounced in down-trends. It can be accurately quantified by quadratic polynomials of today's trend strengths, which refine common mean-reversion models of volatilities and correlations. Our results improve the prediction of market risk by accounting for market trends. They also support a recent proposal to model financial markets by a lattice gas near its critical point.
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Submitted 18 June, 2026;
originally announced June 2026.
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Initial performance results of the JUNO detector
Authors:
Angel Abusleme,
Thomas Adam,
Kai Adamowicz,
David Adey,
Shakeel Ahmad,
Rizwan Ahmed,
Timo Ahola,
Sebastiano Aiello,
Fengpeng An,
Guangpeng An,
Costas Andreopoulos,
Giuseppe Andronico,
João Pedro Athayde Marcondes de André,
Nikolay Anfimov,
Vito Antonelli,
Tatiana Antoshkina,
Burin Asavapibhop,
Didier Auguste,
Margherita Buizza Avanzini,
Andrej Babic,
Jingzhi Bai,
Weidong Bai,
Nikita Balashov,
Roberto Barbera,
Andrea Barresi
, et al. (1114 additional authors not shown)
Abstract:
The Jiangmen Underground Neutrino Observatory (JUNO) started physics data taking on 26 August 2025. JUNO consists of a 20-kton liquid scintillator central detector, surrounded by a 35 kton water pool serving as a Cherenkov veto, and almost 1000 m$^2$ of plastic scintillator veto on top. The detector is located in a shallow underground laboratory with an overburden of 1800 m.w.e. This paper present…
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The Jiangmen Underground Neutrino Observatory (JUNO) started physics data taking on 26 August 2025. JUNO consists of a 20-kton liquid scintillator central detector, surrounded by a 35 kton water pool serving as a Cherenkov veto, and almost 1000 m$^2$ of plastic scintillator veto on top. The detector is located in a shallow underground laboratory with an overburden of 1800 m.w.e. This paper presents the performance results of the detector, extensively studied during the commissioning of the water phase, the subsequent liquid scintillator filling phase, and the first physics runs. The liquid scintillator achieved an attenuation length of 20.6 m at 430 nm, while the high coverage PMT system and scintillator together yielded about 1785 photoelectrons per MeV of energy deposit at the detector centre, measured using the 2.223 MeV $γ$ from neutron captures on hydrogen with an Am-C calibration source. The reconstructed energy resolution is 3.4% for two 0.511 MeV $γ$ at the detector centre and 2.9% for the 0.93 MeV quenched Po-214 alpha decays from natural radioactive sources. The energy nonlinearity is calibrated to better than 1%. Intrinsic contaminations of U-238 and Th-232 in the liquid scintillator are below 10$^{-16}$ g/g, assuming secular equilibrium. The water Cherenkov detector achieves a muon detection efficiency better than 99.9% for muons traversing the liquid scintillator volume. During the initial science runs, the data acquisition duty cycle exceeded 97.8%, demonstrating the excellent stability and readiness of JUNO for high-precision neutrino physics.
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Submitted 18 November, 2025;
originally announced November 2025.
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Lateral Contrast Enhancement in Tomographic Volumetric 3D-Printing via Binary Photoinhibition
Authors:
Bin Wang,
Weichao Sun Hossein Safari,
S. Kaveh Hedayati,
Jadze P. C. Narag,
Thor D. V. Christiansen,
Adrian A. Schiefler,
Henning O. Sørensen,
Jeppe R. Frisvad,
Kristoffer Almdal,
Aminul Islam,
Yi Yang
Abstract:
Tomographic volumetric 3D-printing (TVP) utilizes a nonlinear photoresponse of polymer precursor to cure all points in a three-dimensional (3D) object in parallel. A key challenge in TVP is to build up dose contrast between in-part and out-of-part points in a lateral plane, which relies on coordinated illumination from various projecting angles. This challenge has mainly been tackled by projection…
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Tomographic volumetric 3D-printing (TVP) utilizes a nonlinear photoresponse of polymer precursor to cure all points in a three-dimensional (3D) object in parallel. A key challenge in TVP is to build up dose contrast between in-part and out-of-part points in a lateral plane, which relies on coordinated illumination from various projecting angles. This challenge has mainly been tackled by projection optimization. Here we show that designing material responses to photo-excitation can be a more effective way of addressing this challenge. By introducing a secondary photo-inhibitory species that reacts to external ultraviolet (UV) stimulus, we create a binary photoinhibition (BPI) system that greatly enhances the achievable dose contrast in a lateral plane. We first show that, in theory, combining dose subtraction with sufficient projection angles can guarantee an exact mathematical reconstruction of any greyscale design. We then propose a theoretical framework for BPI, in which a single stationary state with swappable stability can be used to realize dose subtraction. We use oxygen-lophyl radical pair as an approximation to show improvements in print quality enabled by enhanced dose contrast. In situ shadowgraphy shows that BPI improves the lateral patterning with various geometric features, creating differentiable changes in refractive index within 54 um or less. We show qualitative improvements in surface features and internal hollowness in physical prints. The direct impacts of UV light on the formation of positive and negative features on vertical and lateral planes of 5 workpieces are analyzed quantitatively. We conclude that introducing BPI with UV irradiation grants us direct control over the formation of negative features on the lateral plane.
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Submitted 1 March, 2025; v1 submitted 24 March, 2023;
originally announced March 2023.