Showing 1–50 of 79 results for author: Han, K

Worldwide Reactor Neutrino Propagation to Underground Labs: Matter Effects and Flux Predictions

Authors: Keyu Han, Juncheng Qian, Shaomin Chen

Abstract: As a unique probe for geophysical research, geoneutrinos can reveal the distribution of internal heat sources in the Earth by detecting electron antineutrinos produced by the radioactive decay of $^{238}$U, $^{232}$Th, and $^{40}$K. However, commercial nuclear power plants continuously produce the same type of electron antineutrinos, which constitute a primary background difficult to eliminate in… ▽ More As a unique probe for geophysical research, geoneutrinos can reveal the distribution of internal heat sources in the Earth by detecting electron antineutrinos produced by the radioactive decay of $^{238}$U, $^{232}$Th, and $^{40}$K. However, commercial nuclear power plants continuously produce the same type of electron antineutrinos, which constitute a primary background difficult to eliminate in geoneutrino experiments. As geoneutrino measurements and reactor background modeling approach sub-percent precision, even small matter-induced corrections to reactor antineutrino propagation require quantitative assessment. In this paper, we develop a high-precision prediction framework for reactor neutrino fluxes at underground labs, using global reactor operating data, reactor-to-detector distances, and matter effects (MSW) on neutrino propagation through the Earth. To solve the three-flavor MSW evolution efficiently, we implement a second-order Strang-splitting solver in the vacuum mass basis. Within this framework, we have calculated the reactor neutrino oscillation probabilities, including the MSW effect under one-dimensional (spherically symmetric) and three-dimensional (including lateral inhomogeneities) Earth models, and compared them with the vacuum oscillation scenario, to assess the impact of Earth's structural features on the accuracy of reactor neutrino flux predictions. △ Less

Submitted 26 March, 2026; originally announced March 2026.

Precise $^{136}$Xe Double Beta Decay Measurement in PandaX-4T with Implications on the Nuclear Matrix Elements and Majorons

Authors: PandaX Collaboration, Zhe Yuan, Zihao Bo, Wei Chen, Xun Chen, Yunhua Chen, Chen Cheng, Xiangyi Cui, Manna Deng, Yingjie Fan, Deqing Fang, Xuanye Fu, Zhixing Gao, Yujie Ge, Lisheng Geng, Karl Giboni, Xunan Guo, Xuyuan Guo, Zichao Guo, Chencheng Han, Ke Han, Changda He, Jinrong He, Houqi Huang, Junting Huang , et al. (89 additional authors not shown)

Abstract: The continuous spectrum of double beta decay ($ββ$) provides a sensitive probe to test the predictions of the standard model and to search for signatures of new physics beyond it. We present a comprehensive analysis of the $^{136}$Xe $ββ$ spectrum utilizing $39.1 \pm 0.7~\textrm{kg}\cdot\textrm{yr}$ of $^{136}$Xe exposure from the PandaX-4T experiment. The analysis yields the most precise measurem… ▽ More The continuous spectrum of double beta decay ($ββ$) provides a sensitive probe to test the predictions of the standard model and to search for signatures of new physics beyond it. We present a comprehensive analysis of the $^{136}$Xe $ββ$ spectrum utilizing $39.1 \pm 0.7~\textrm{kg}\cdot\textrm{yr}$ of $^{136}$Xe exposure from the PandaX-4T experiment. The analysis yields the most precise measurement to date of the $^{136}$Xe two-neutrino double beta decay ($2νββ$) half-life, $(2.14 \pm 0.05) \times 10^{21}$ years, the uncertainty of which is reduced by a factor of 2 compared to our previous result. We measure the parameter $ξ_{31}^{2ν}$, defined as the ratio between the subleading and leading components of the $^{136}$Xe $2νββ$ nuclear matrix element, to be $0.59^{+0.41}_{-0.38}$, which is consistent with theoretical predictions. We also search for Majoron-emitting modes of $^{136}$Xe $ββ$, establishing the most stringent limit for the spectral index $n=7$. △ Less

Submitted 9 April, 2026; v1 submitted 4 December, 2025; originally announced December 2025.

Comments: 8 pages, 4 figures

Journal ref: Phys. Rev. Lett. 136, 162501 (2026)

Experimental study of the reaction $Ξ^{0}n\rightarrowΛΛX$ using $Ξ^{0}$-nucleus scattering

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai , et al. (707 additional authors not shown)

Abstract: Using $(10087\pm44)\times10^{6}$$J/ψ$ events collected with the BESIII detector operating at the BEPCII storage ring in $2009$, $2012$, $2018$, and $2019$, we perform a search for the reaction $Ξ^0n\rightarrowΛΛX$, where $X$ denotes any additional final particles. Given the highly suppressed phase space for producing extra pions, the $X$ consists of either nothing or a photon, corresponding to the… ▽ More Using $(10087\pm44)\times10^{6}$$J/ψ$ events collected with the BESIII detector operating at the BEPCII storage ring in $2009$, $2012$, $2018$, and $2019$, we perform a search for the reaction $Ξ^0n\rightarrowΛΛX$, where $X$ denotes any additional final particles. Given the highly suppressed phase space for producing extra pions, the $X$ consists of either nothing or a photon, corresponding to the processes $Ξ^0 n \rightarrow ΛΛ$ and $Ξ^{0}n\rightarrowΛΣ^0\rightarrowΛΛγ$. The $Ξ^0$ comes from the decay of $J/ψ\rightarrowΞ^0\barΞ^0$, while the neutron originates from material of the beam pipe. A signal is observed for the first time with a statistical significance of 6.4$σ$. The cross section for the reaction $Ξ^0+{^9\rm{Be}}\rightarrowΛ+Λ+X$ is measured to be $(43.6\pm10.5_{\text{stat}}\pm11.1_{\text{syst}})$ mb at $P_{Ξ^0}\approx0.818$ GeV/$c$, where the first uncertainty is statistical and the second systematic. No significant $H$-dibaryon signal is observed in the $ΛΛ$ final state. △ Less

Submitted 26 February, 2026; v1 submitted 4 December, 2025; originally announced December 2025.

Comments: 9 pages, 3 figures

End-to-End Data Analysis Methods for the CUORE Experiment

Authors: D. Q. Adams, C. Alduino, K. Alfonso, A. Armatol, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Beretta, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, A. Campani, J. Cao, C. Capelli, S. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, E. Celi , et al. (95 additional authors not shown)

Abstract: The Cryogenic Underground Observatory for Rare Events (CUORE) experiment set the most stringent limit on the neutrinoless double-beta ($0νββ$) decay half-life of $^{130}$Te with 2 ton yr TeO$_2$ analyzed exposure. In addition to $0νββ$ decay, the CUORE detector -- a ton-scale array of nearly 1000 cryogenic calorimeters operating at $\sim$10 mK -- is capable of searching for other rare decays and i… ▽ More The Cryogenic Underground Observatory for Rare Events (CUORE) experiment set the most stringent limit on the neutrinoless double-beta ($0νββ$) decay half-life of $^{130}$Te with 2 ton yr TeO$_2$ analyzed exposure. In addition to $0νββ$ decay, the CUORE detector -- a ton-scale array of nearly 1000 cryogenic calorimeters operating at $\sim$10 mK -- is capable of searching for other rare decays and interactions over a broad energy range. For our searches, we leverage the available information of each calorimeter by performing its optimization, data acquisition, and analysis independently. We describe the analysis tools and methods developed for CUORE and their application to build high-quality datasets for numerous physics searches. In particular, we describe in detail our evaluation of the energy-dependent detector response and signal efficiency used in the most recent search for $0νββ$ decay. △ Less

Submitted 29 October, 2025; originally announced October 2025.

Tomographic beta-gamma spectroscopy of nuclear beta decay

Authors: PandaX Collaboration, Zhe Yuan, Zihao Bo, Wei Chen, Xun Chen, Yunhua Chen, Chen Cheng, Xiangyi Cui, Manna Deng, Yingjie Fan, Deqing Fang, Xuanye Fu, Zhixing Gao, Yujie Ge, Lisheng Geng, Karl Giboni, Xunan Guo, Xuyuan Guo, Zichao Guo, Chencheng Han, Ke Han, Changda He, Jinrong He, Houqi Huang, Junting Huang , et al. (89 additional authors not shown)

Abstract: Nuclear $β$ decay, a sensitive probe of nuclear structure and weak interactions, has become a precision test bed for physics beyond the Standard Model, driven by recent advances in spectrometric techniques. Here we introduce tomographic $β$-$γ$ spectroscopy (TBGS) of nuclear $β$ decay, a method that detects the energies of $β$, $γ$, and internal conversion electrons while simultaneously reconstruc… ▽ More Nuclear $β$ decay, a sensitive probe of nuclear structure and weak interactions, has become a precision test bed for physics beyond the Standard Model, driven by recent advances in spectrometric techniques. Here we introduce tomographic $β$-$γ$ spectroscopy (TBGS) of nuclear $β$ decay, a method that detects the energies of $β$, $γ$, and internal conversion electrons while simultaneously reconstructing the energy deposition vertices. Using the PandaX-4T detector operated as a TBGS, we obtain a precise and unbiased decay scheme of $^{214}$Pb, a key background isotope in searches for dark matter and Majorana neutrinos. For the first time, transitions of $^{214}$Pb to both the ground and excited states of $^{214}$Bi are measured concurrently, revealing discrepancies in branching ratios of up to 4.7$σ$ relative to previous evaluations. Combined with state-of-the-art theoretical spectral-shape calculations, these results establish a new benchmark for background modelling in rare-event searches and highlight the potential of TBGS as a versatile tool for fundamental physics and nuclear applications. △ Less

Submitted 29 November, 2025; v1 submitted 28 October, 2025; originally announced October 2025.

Precision measurement and modelling of the threshold-free 210Pb β spectrum

Authors: Shuo Zhang, Hao-Ran Liu, Ke Han, Xavier Mougeot, Paul-Antoine Hervieux, Tao Sun, Wen-Tao Wu, Robin Cantor, Jing-Kai Xia, Zhi Liu, Jun-Cheng Liang, Fu-You Fan, Le Zhang, Ming-Yu Ge, Xiao-Peng Zhou, Adrien Andoche

Abstract: Beta decay is a fundamental process that governs nuclear stability and serves as a sensitive probe of the weak interaction and possible physics beyond the Standard Model of particle physics. However, precise measurements of complete $β$ decay spectra, particularly at low energies, remain experimentally and theoretically challenging. Here we report a high-precision, threshold-free measurement of th… ▽ More Beta decay is a fundamental process that governs nuclear stability and serves as a sensitive probe of the weak interaction and possible physics beyond the Standard Model of particle physics. However, precise measurements of complete $β$ decay spectra, particularly at low energies, remain experimentally and theoretically challenging. Here we report a high-precision, threshold-free measurement of the full $β$ decay spectrum of 210Pb to excited states of 210Bi, using a transition-edge sensor (TES)-based micro-calorimeter. This approach enables the detection of $β$ particle energies from 0 keV up to their endpoint by coincidence summing with subsequent de-excitation energy, thereby eliminating reconstruction artifacts near zero energy that have traditionally limited low-energy spectral accuracy. To our knowledge, this is the first complete, high-precision $β$ decay spectrum from 0 keV. The data resolve theoretical uncertainties associated with the atomic quantum exchange (AQE) effect. An accompanying ab initio theoretical framework, incorporating atomic, leptonic, and nuclear components, predicts a statistically significant (7.2 {$σ$}) enhancement in $β$ emission probability near zero energy, in agreement with the measurement and in contrast to models that omit AQE corrections. These results provide a new benchmark for $β$ decay theory at low energies, deepen our understanding of the weak interaction, and establish a critical foundation for searches for new physics, including dark matter interactions and precision studies of neutrinos. △ Less

Submitted 1 October, 2025; v1 submitted 30 September, 2025; originally announced September 2025.

Comments: 14 pages, 7 figures

Sensitivity of neutrinoless double beta decays from a combined analysis of ground and excited states

Authors: C. R. Ding, K. Han, S. B. Wang, J. M. Yao

Abstract: Next-generation neutrinoless double-beta ($0νββ$) decay experiments, with projected half-life sensitivities approaching $10^{28}$ years, aim to probe the entire parameter space of the inverted neutrino mass ordering in the light-neutrino-exchange scenario. However, this reach remains uncertain by the substantial model dependence of the nuclear matrix elements (NMEs). In this work, we propose a str… ▽ More Next-generation neutrinoless double-beta ($0νββ$) decay experiments, with projected half-life sensitivities approaching $10^{28}$ years, aim to probe the entire parameter space of the inverted neutrino mass ordering in the light-neutrino-exchange scenario. However, this reach remains uncertain by the substantial model dependence of the nuclear matrix elements (NMEs). In this work, we propose a strategy based on a combined analysis of $0νββ$ decays to both the ground state and the first excited $0^+$ state of the daughter nucleus. We show that such a multi-channel approach can significantly enhance experimental sensitivity, depending on the underlying NME predictions. This method is particularly well-suited for large liquid xenon detectors, such as the proposed PandaX-xT and XLZD experiments, which can efficiently identify transitions of $^{136}$Xe to excited states. Our results highlight the importance of exploiting multiple decay channels in future $0νββ$ searches to maximize their discovery potential. △ Less

Submitted 31 May, 2026; v1 submitted 24 August, 2025; originally announced August 2025.

Comments: 6 pages, 3 figures, 2 table

Journal ref: Phys. Lett. B 879 (2026) 140623

Precise Measurement of $^{216}$Po Half-life with Exact Parent-daughter Pairing in PandaX-4T

Authors: PandaX Collaboration, Chenxiang Li, Zihao Bo, Wei Chen, Xun Chen, Yunhua Chen, Chen Cheng, Xiangyi Cui, Manna Deng, Yingjie Fan, Deqing Fang, Xuanye Fu, Zhixing Gao, Yujie Ge, Lisheng Geng, Karl Giboni, Xunan Guo, Xuyuan Guo, Zichao Guo, Chencheng Han, Ke Han, Changda He, Jinrong He, Houqi Huang, Junting Huang , et al. (86 additional authors not shown)

Abstract: We report a precise measurement of $^{216}\rm Po$ half-life using the PandaX-4T liquid xenon time projection chamber (TPC). $^{220}\rm Rn $, emanating from a $^{228}\rm Th $ calibration source, is injected to the detector and undergoes successive $α$ decays, first to $^{216}\rm Po$ and then to $^{212}\rm Pb$. PandaX-4T detector measures the 5-dimensional (5D) information of each decay, including t… ▽ More We report a precise measurement of $^{216}\rm Po$ half-life using the PandaX-4T liquid xenon time projection chamber (TPC). $^{220}\rm Rn $, emanating from a $^{228}\rm Th $ calibration source, is injected to the detector and undergoes successive $α$ decays, first to $^{216}\rm Po$ and then to $^{212}\rm Pb$. PandaX-4T detector measures the 5-dimensional (5D) information of each decay, including time, energy, and 3-dimensional positions. Therefore, we can identify the $^{220}\rm Rn $ and $^{216}\rm Po$ decay events and pair them exactly to extract the lifetime of each $^{216}\rm Po$. With a large data set and high-precision $^{220}\rm $Rn-$^{216}\rm $Po pairing technique, we measure the $^{216}\rm Po$ half-life to be $143.7\pm0.5$ ms, which is the most precise result to date and agrees with previously published values. The leading precision of this measurement demonstrates the power of 5D calorimeter and the potential of exact parent-daughter pairing in the xenon TPC. △ Less

Submitted 17 July, 2025; originally announced July 2025.

First measurement of $Σ^{+}n\rightarrowΛp$ and $Σ^{+}n\rightarrowΣ^{0}p$ cross sections via $Σ^+$-nucleus scattering at an electron-positron collider

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai , et al. (680 additional authors not shown)

Abstract: Using $(1.0087\pm0.0044)\times10^{10}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring, the reactions $Σ^{+}n\rightarrowΛp$ and $Σ^{+}n\rightarrowΣ^{0}p$ are studied, where the $Σ^{+}$ baryon is produced in the process $J/ψ\rightarrowΣ^{+}\barΣ^-$ and the neutron is a component of the $^9\rm{Be}$, $^{12}\rm{C}$ and $^{197}\rm{Au}$ nuclei in the beam pipe. Clear signals o… ▽ More Using $(1.0087\pm0.0044)\times10^{10}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring, the reactions $Σ^{+}n\rightarrowΛp$ and $Σ^{+}n\rightarrowΣ^{0}p$ are studied, where the $Σ^{+}$ baryon is produced in the process $J/ψ\rightarrowΣ^{+}\barΣ^-$ and the neutron is a component of the $^9\rm{Be}$, $^{12}\rm{C}$ and $^{197}\rm{Au}$ nuclei in the beam pipe. Clear signals of these two reactions are observed for the first time. Their cross sections are measured to be $σ(Σ^{+}+{^9\rm{Be}}\rightarrowΛ+p+X)=(45.2\pm12.1_{\rm{stat}}\pm7.2_{\rm{sys}})$ mb and $σ(Σ^{+}+{^9\rm{Be}}\rightarrowΣ^{0}+p+X)=(29.8\pm9.7_{\rm{stat}}\pm6.9_{\rm{sys}})$ mb for a $Σ^{+}$ average momentum of $0.992$ GeV/$c$, within a range of $\pm0.015$ GeV/$c$, where $X$ represents the residual nucleus. This is the first study of $Σ^{+}$-nucleon scattering at an electron-positron collider. △ Less

Submitted 24 March, 2026; v1 submitted 26 May, 2025; originally announced May 2025.

Comments: 9 pages, 2 figures

Journal ref: Physical Review C 113, L032201 (2026)

The detection of marine microseismic activity with the CUORE tonne-scale cryogenic experiment

Authors: D. Q. Adams, C. Alduino, K. Alfonso, A. Armatol, F. T. Avignone, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Beretta, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, A. Campani, J. Cao, C. Capelli, S. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, E. Celi , et al. (104 additional authors not shown)

Abstract: Vibrations from experimental setups and the environment are a persistent source of noise for low-temperature calorimeters searching for rare events, including neutrinoless double beta ($0νββ$) decay or dark matter interactions. Such noise can significantly limit experimental sensitivity to the physics case under investigation. Here we report the first detection of marine microseismic vibrations us… ▽ More Vibrations from experimental setups and the environment are a persistent source of noise for low-temperature calorimeters searching for rare events, including neutrinoless double beta ($0νββ$) decay or dark matter interactions. Such noise can significantly limit experimental sensitivity to the physics case under investigation. Here we report the first detection of marine microseismic vibrations using mK-scale calorimeters. This study employs a multi-device analysis correlating data from CUORE, the leading experiment in the search for $0νββ$ decay with mK-scale calorimeters and the Copernicus Earth Observation program, revealing the seasonal impact of Mediterranean Sea activity on CUORE's energy thresholds, resolution, and sensitivity over four years. The detection of marine microseisms underscores the need to address faint environmental noise in ultra-sensitive experiments. Understanding how such noise couples to the detector and developing mitigation strategies is essential for next-generation experiments. We demonstrate one such strategy: a noise decorrelation algorithm implemented in CUORE using auxiliary sensors, which reduces vibrational noise and improves detector performance. Enhancing sensitivity to $0νββ$ decay and to rare events with low-energy signatures requires identifying unresolved noise sources, advancing noise reduction methods, and improving vibration suppression systems, all of which inform the design of next-generation rare event experiments. △ Less

Submitted 6 May, 2026; v1 submitted 13 May, 2025; originally announced May 2025.

Comments: Published version (open access, CC BY 4.0)

Journal ref: Communications Physics 9, 121 (2026)

Sensitivity of the CUPID experiment to $0νββ$ decay of $^{100}$Mo

Authors: K. Alfonso, A. Armatol, C. Augier, F. T. Avignone III, O. Azzolini, A. S. Barabash, G. Bari, A. Barresi, D. Baudin, F. Bellini, G. Benato, L. Benussi, V. Berest, M. Beretta, L. Bergé, M. Bettelli, M. Biassoni, J. Billard, F. Boffelli, V. Boldrini, E. D. Brandani, C. Brofferio, C. Bucci, M. Buchynska, J. Camilleri , et al. (167 additional authors not shown)

Abstract: CUPID is a next-generation bolometric experiment to search for neutrinoless double-beta decay ($0νββ$) of $^{100}$Mo using Li$_2$MoO$_4$ scintillating crystals. It will operate 1596 crystals at $\sim$10 mK in the CUORE cryostat at the Laboratori Nazionali del Gran Sasso in Italy. Each crystal will be facing two Ge-based bolometric light detectors for $α$ rejection. We compute the discovery and the… ▽ More CUPID is a next-generation bolometric experiment to search for neutrinoless double-beta decay ($0νββ$) of $^{100}$Mo using Li$_2$MoO$_4$ scintillating crystals. It will operate 1596 crystals at $\sim$10 mK in the CUORE cryostat at the Laboratori Nazionali del Gran Sasso in Italy. Each crystal will be facing two Ge-based bolometric light detectors for $α$ rejection. We compute the discovery and the exclusion sensitivity of CUPID to $0νββ$ in a Frequentist and a Bayesian framework. This computation is done numerically based on pseudo-experiments. For the CUPID baseline scenario, with a background and an energy resolution of $1.0 \times 10^{-4}$ counts/keV/kg/yr and 5 keV FWHM at the Q-value, respectively, this results in a Bayesian exclusion sensitivity (90% c.i.) of $\hat{T}_{1/2} > 1.6 \times 10^{27} \ \mathrm{yr}$, corresponding to the effective Majorana neutrino mass of $\hat{m}_{ββ} < \ 9.6$ -- $28 \ \mathrm{meV}$. The Frequentist discovery sensitivity (3$σ$) is $\hat{T}_{1/2}= 1.0 \times 10^{27} \ \mathrm{yr}$, corresponding to $\hat{m}_{ββ}= \ 12$ -- $36 \ \mathrm{meV}$. △ Less

Submitted 2 February, 2026; v1 submitted 19 April, 2025; originally announced April 2025.

Comments: Accepted for publication in European Physical Journal C

Half-life and precision shape measurement of 2νββ decay of $^{130}$Te

Authors: D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Beretta, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, A. Campani, J. Cao, C. Capelli, S. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, E. Celi, D. Chiesa , et al. (97 additional authors not shown)

Abstract: We present a new measurement of the 2nbb half-life of 130Te (T1/2) using the first complete model of the CUORE data, based on 1038 kg yr of collected exposure. Thanks to optimized data selection, we achieve a factor of two improvement in precision, obtaining T1/2 = (9.32 +0.05 -0.04 (stat.) +0.07 -0.07 (syst.)) x10^20 yr. The signal-to-background ratio is increased by 70% compared to our previous… ▽ More We present a new measurement of the 2nbb half-life of 130Te (T1/2) using the first complete model of the CUORE data, based on 1038 kg yr of collected exposure. Thanks to optimized data selection, we achieve a factor of two improvement in precision, obtaining T1/2 = (9.32 +0.05 -0.04 (stat.) +0.07 -0.07 (syst.)) x10^20 yr. The signal-to-background ratio is increased by 70% compared to our previous results, enabling the first application of the improved 2nbb formalism to 130Te. Within this framework, we determine a credibility interval for the effective axial coupling in the nuclear medium as a function of nuclear matrix elements. We also extract values for the higher-order nuclear matrix element ratios: second-to-first and third-to-first. The second-to-first ratio agrees with nuclear model predictions, while the third-to-first ratio deviates from theoretical expectations. These findings provide essential tests of nuclear models and key inputs for future 0nbb searches. △ Less

Submitted 31 March, 2025; originally announced March 2025.

Innovating Bolometers' Mounting: A Gravity-Based Approach

Authors: The CUPID Collaboration, K. Alfonso, A. Armatol, C. Augier, F. T. Avignone III, O. Azzolini, A. S. Barabash, G. Bari, A. Barresi, D. Baudin, F. Bellini, G. Benato, L. Benussi, V. Berest, M. Beretta, M. Bettelli, M. Biassoni, J. Billard, F. Boffelli, V. Boldrini, E. D. Brandani, C. Brofferio, C. Bucci, M. Buchynska, J. Camilleri , et al. (168 additional authors not shown)

Abstract: Cryogenic calorimeters, also known as bolometers, are among the leading technologies for searching for rare events. The CUPID experiment is exploiting this technology to deploy a tonne-scale detector to search for neutrinoless double-beta decay of $^{100}$Mo. The CUPID collaboration proposed an innovative approach to assembling bolometers in a stacked configuration, held in position solely by grav… ▽ More Cryogenic calorimeters, also known as bolometers, are among the leading technologies for searching for rare events. The CUPID experiment is exploiting this technology to deploy a tonne-scale detector to search for neutrinoless double-beta decay of $^{100}$Mo. The CUPID collaboration proposed an innovative approach to assembling bolometers in a stacked configuration, held in position solely by gravity. This gravity-based assembly method is unprecedented in the field of bolometers and offers several advantages, including relaxed mechanical tolerances and simplified construction. To assess and optimize its performance, we constructed a medium-scale prototype hosting 28 Li$_2$MoO$_4$ crystals and 30 Ge light detectors, both operated as cryogenic calorimeters at the Laboratori Nazionali del Gran Sasso (Italy). Despite an unexpected excess of noise in the light detectors, the results of this test proved (i) a thermal stability better than $\pm$0.5 mK at 10 mK, (ii) a good energy resolution of Li$_2$MoO$_4$ bolometers, (6.6 $\pm$ 2.2) keV FWHM at 2615 keV, and (iii) a Li$_2$MoO$_4$ light yield measured by the closest light detector of 0.36 keV/MeV, sufficient to guarantee the particle identification requested by CUPID. △ Less

Submitted 6 March, 2025; originally announced March 2025.

CUPID, the CUORE Upgrade with Particle IDentification

Authors: The CUPID Collaboration, K. Alfonso, A. Armatol, C. Augier, F. T. Avignone III, O. Azzolini, A. S. Barabash, G. Bari, A. Barresi, D. Baudin, F. Bellini, G. Benato, L. Benussi, V. Berest, M. Beretta, L. Bergé, M. Bettelli, M. Biassoni, J. Billard, F. Boffelli, V. Boldrini, E. D. Brandani, C. Brofferio, C. Bucci, M. Buchynska , et al. (168 additional authors not shown)

Abstract: CUPID, the CUORE Upgrade with Particle IDentification, is a next-generation experiment to search for neutrinoless double beta decay ($0νββ$) and other rare events using enriched Li$_2$$^{100}$MoO$_4$ scintillating bolometers. It will be hosted by the CUORE cryostat located at the Laboratori Nazionali del Gran Sasso in Italy. The main physics goal of CUPID is to search for $0νββ$\ of $^{100}$Mo wit… ▽ More CUPID, the CUORE Upgrade with Particle IDentification, is a next-generation experiment to search for neutrinoless double beta decay ($0νββ$) and other rare events using enriched Li$_2$$^{100}$MoO$_4$ scintillating bolometers. It will be hosted by the CUORE cryostat located at the Laboratori Nazionali del Gran Sasso in Italy. The main physics goal of CUPID is to search for $0νββ$\ of $^{100}$Mo with a discovery sensitivity covering the full neutrino mass regime in the inverted ordering scenario, as well as the portion of the normal ordering regime with lightest neutrino mass larger than 10 meV. With a conservative background index of 10$^{-4}$ cnts/(keV$\cdot$kg$\cdot$yr), 240 kg isotope mass, 5 keV FWHM energy resolution at 3 MeV and 10 live-years of data taking, CUPID will have a 90\% C.L. half-life exclusion sensitivity of 1.8 $\cdot$ 10$^{27}$ yr, corresponding to an effective Majorana neutrino mass ($m_{ββ}$) sensitivity of 9--15 meV, and a $3σ$ discovery sensitivity of 1 $\cdot$ 10$^{27}$ yr, corresponding to an $m_{ββ}$ range of 12--21 meV. △ Less

Submitted 11 July, 2025; v1 submitted 1 March, 2025; originally announced March 2025.

Comments: Accepted for publication by EPJC; 25 pages, 6 figures, and 2 tables

Journal ref: Eur. Phys. J. C 85, 737 (2025)

Search for Double Beta Decay of $^{136}$Xe to the $0^+_1$ Excited State of $^{136}$Ba with PandaX-4T

Authors: PandaX Collaboration, Lingyin Luo, Zihao Bo, Wei Chen, Xun Chen, Yunhua Chen, Zhaokan Cheng, Xiangyi Cui, Yingji Fang, Deqing Fang, Zhixing Gao, Lisheng Geng, Karl Giboni, Xunan Guo, Xuyuan Guo, Zichao Guo, Chencheng Han, Ke Han, Changda He, Jinrong He, Di Huang, Houqi Huang, Junting Huang, Ruquan Hou, Yu Hou , et al. (76 additional authors not shown)

Abstract: We perform a search of double beta decay of $^{136}$Xe to the excited state, $0^+_1$, of $^{136}$Ba (2$νββ$-0$_1^+$), using the dual-phase xenon detector of PandaX-4T with the first 94.9-day commissioning data. The multi-site events are reconstructed up to the MeV energy scale, which helps to improve the background model significantly. The background contribution from the stainless steel platform… ▽ More We perform a search of double beta decay of $^{136}$Xe to the excited state, $0^+_1$, of $^{136}$Ba (2$νββ$-0$_1^+$), using the dual-phase xenon detector of PandaX-4T with the first 94.9-day commissioning data. The multi-site events are reconstructed up to the MeV energy scale, which helps to improve the background model significantly. The background contribution from the stainless steel platform outside PandaX-4T cryostat is evaluated for the first time. No significant evidence for 2$νββ$-$0_1^+$ is observed, resulting in a lower limit on half-life of $7.5 \times 10^{22}$ yr at the 90% confidence level. This is the first experimental limit on such a rare decay in a natural xenon-based detector. △ Less

Submitted 7 March, 2025; v1 submitted 5 February, 2025; originally announced February 2025.

Searching for Neutrinoless Double-Beta Decay of $^{136}$Xe with PandaX-4T

Authors: PandaX Collaboration, Shu Zhang, Zihao Bo, Wei Chen, Xun Chen, Yunhua Chen, Zhaokan Cheng, Xiangyi Cui, Yingjie Fan, Deqing Fang, Zhixing Gao, Lisheng Geng, Karl Giboni, Xunan Guo, Xuyuan Guo, Zichao Guo, Chencheng Han, Ke Han, Changda He, Jinrong He, Di Huang, Houqi Huang, Junting Huang, Ruquan Hou, Yu Hou , et al. (77 additional authors not shown)

Abstract: We report the search for neutrinoless double-beta decay of $^{136}$Xe from the PandaX-4T experiment with a 3.7-tonne natural xenon target. The data reconstruction and the background modeling are optimized in the MeV energy region. A blind analysis is performed with data from the commissioning run and the first science run. No significant excess of signal over the background is observed. A lower li… ▽ More We report the search for neutrinoless double-beta decay of $^{136}$Xe from the PandaX-4T experiment with a 3.7-tonne natural xenon target. The data reconstruction and the background modeling are optimized in the MeV energy region. A blind analysis is performed with data from the commissioning run and the first science run. No significant excess of signal over the background is observed. A lower limit on the half-life of $^{136}$Xe neutrinoless double-beta decay is established to be $2.1 \times 10^{24}$~yr at the 90\% confidence level, with a $^{136}$Xe exposure of 44.6~kg$\cdot$year. Our result represents the most stringent constraint from a natural xenon detector to date. △ Less

Submitted 18 December, 2024; originally announced December 2024.

Comments: 9 pages, 4 figures, 2 tables

Measurement of two-neutrino double electron capture half-life of $^{124}$Xe with PandaX-4T

Authors: PandaX Collaboration, Zihao Bo, Wei Chen, Xun Chen, Yunhua Chen, Zhaokan Cheng, Xiangyi Cui, Yingjie Fan, Deqing Fang, Zhixing Gao, Lisheng Geng, Karl Giboni, Xunan Guo, Xuyuan Guo, Zichao Guo, Chencheng Han, Ke Han, Changda He, Jinrong He, Di Huang, Houqi Huang, Junting Huang, Ruquan Hou, Yu Hou, Xiangdong Ji , et al. (77 additional authors not shown)

Abstract: Detailed studies of two-neutrino double electron capture (2$ν$DEC) is a crucial step towards searching for the neutrino-less mode to explore the Majorana nature of neutrinos. We have measured precisely the half-life of the 2$ν$DEC process in $^{124}$Xe, utilizing a total exposure of 1.73 tonne$\cdot$year from the commissioning run and the first science run of the PandaX-4T experiment. A time-depen… ▽ More Detailed studies of two-neutrino double electron capture (2$ν$DEC) is a crucial step towards searching for the neutrino-less mode to explore the Majorana nature of neutrinos. We have measured precisely the half-life of the 2$ν$DEC process in $^{124}$Xe, utilizing a total exposure of 1.73 tonne$\cdot$year from the commissioning run and the first science run of the PandaX-4T experiment. A time-dependent background model in the $\mathcal{O}$(10 keV) energy is constructed for the first time in PandaX-4T data. With an unbinned maximum likelihood fit, we determine the half-life of the 2$ν$DEC process to be $(1.03\pm0.15_{\rm stat}\pm0.08_{\rm sys})\times 10^{22}$$\,$yr. Furthermore, we have evaluated the branching ratio for both electrons captured from the $K$ shell ($KK$) to be $(65\pm5)\%$, which aligns with the $^{124}$Xe nuclear model calculations within 1.8$\,$$σ$. △ Less

Submitted 16 May, 2025; v1 submitted 21 November, 2024; originally announced November 2024.

Comments: 19 pages, 5 figures, 4 tables; version3 accepted by JHEP

Observation of a rare beta decay of the charmed baryon with a Graph Neural Network

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, O. Afedulidis, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, I. Balossino, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere , et al. (637 additional authors not shown)

Abstract: The beta decay of the lightest charmed baryon $Λ_c^+$ provides unique insights into the fundamental mechanism of strong and electro-weak interactions, serving as a testbed for investigating non-perturbative quantum chromodynamics and constraining the Cabibbo-Kobayashi-Maskawa (CKM) matrix parameters. This article presents the first observation of the Cabibbo-suppressed decay… ▽ More The beta decay of the lightest charmed baryon $Λ_c^+$ provides unique insights into the fundamental mechanism of strong and electro-weak interactions, serving as a testbed for investigating non-perturbative quantum chromodynamics and constraining the Cabibbo-Kobayashi-Maskawa (CKM) matrix parameters. This article presents the first observation of the Cabibbo-suppressed decay $Λ_c^+ \rightarrow n e^+ ν_{e}$, utilizing $4.5~\mathrm{fb}^{-1}$ of electron-positron annihilation data collected with the BESIII detector. A novel Graph Neural Network based technique effectively separates signals from dominant backgrounds, notably $Λ_c^+ \rightarrow Λe^+ ν_{e}$, achieving a statistical significance exceeding $10σ$. The absolute branching fraction is measured to be $(3.57\pm0.34_{\mathrm{stat.}}\pm0.14_{\mathrm{syst.}})\times 10^{-3}$. For the first time, the CKM matrix element $\left|V_{cd}\right|$ is extracted via a charmed baryon decay as $0.208\pm0.011_{\rm exp.}\pm0.007_{\rm LQCD}\pm0.001_{τ_{Λ_c^+}}$. This work highlights a new approach to further understand fundamental interactions in the charmed baryon sector, and showcases the power of modern machine learning techniques in experimental high-energy physics. △ Less

Submitted 15 January, 2025; v1 submitted 17 October, 2024; originally announced October 2024.

Comments: 27 pages, 5 figures

Journal ref: Nature Commun. 16, 681 (2025)

First Indication of Solar $^8$B Neutrino Flux through Coherent Elastic Neutrino-Nucleus Scattering in PandaX-4T

Authors: PandaX Collaboration, Zihao Bo, Wei Chen, Xun Chen, Yunhua Chen, Zhaokan Cheng, Xiangyi Cui, Yingjie Fan, Deqing Fang, Zhixing Gao, Lisheng Geng, Karl Giboni, Xunan Guo, Xuyuan Guo, Zichao Guo, Chencheng Han, Ke Han, Changda He, Jinrong He, Di Huang, Houqi Huang, Junting Huang, Ruquan Hou, Yu Hou, Xiangdong Ji , et al. (77 additional authors not shown)

Abstract: The PandaX-4T liquid xenon detector at the China Jinping Underground Laboratory is used to measure the solar $^8$B neutrino flux by detecting neutrinos through coherent scattering with xenon nuclei. Data samples requiring the coincidence of scintillation and ionization signals (paired), as well as unpaired ionization-only signals (US2), are selected with energy threshold of approximately 1.1 keV (… ▽ More The PandaX-4T liquid xenon detector at the China Jinping Underground Laboratory is used to measure the solar $^8$B neutrino flux by detecting neutrinos through coherent scattering with xenon nuclei. Data samples requiring the coincidence of scintillation and ionization signals (paired), as well as unpaired ionization-only signals (US2), are selected with energy threshold of approximately 1.1 keV (0.33 keV) nuclear recoil energy. Combining the commissioning run and the first science run of PandaX-4T, a total exposure of 1.20 and 1.04 tonne$\cdot$year are collected for the paired and US2, respectively. After unblinding, 3 and 332 events are observed with an expectation of 2.8$\pm$0.5 and 251$\pm$32 background events, for the paired and US2 data, respectively. A combined analysis yields a best-fit $^8$B neutrino signal of 3.5 (75) events from the paired (US2) data sample, with $\sim$37\% uncertainty, and the background-only hypothesis is disfavored at 2.64$σ$ significance. This gives a solar $^8$B neutrino flux of ($8.4\pm3.1$)$\times$10$^6$ cm$^{-2}$s$^{-1}$, consistent with the standard solar model prediction. It is also the first indication of solar $^8$B neutrino ``fog'' in a dark matter direct detection experiment. △ Less

Submitted 13 September, 2024; v1 submitted 15 July, 2024; originally announced July 2024.

Comments: Accepted by Physical Review Letters

Data-driven background model for the CUORE experiment

Authors: CUORE Collaboration, D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Beretta, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, A. Campani, J. Cao, S. Capelli, C. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, E. Celi , et al. (93 additional authors not shown)

Abstract: We present the model we developed to reconstruct the CUORE radioactive background based on the analysis of an experimental exposure of 1038.4 kg yr. The data reconstruction relies on a simultaneous Bayesian fit applied to energy spectra over a broad energy range. The high granularity of the CUORE detector, together with the large exposure and extended stable operations, allow for an in-depth explo… ▽ More We present the model we developed to reconstruct the CUORE radioactive background based on the analysis of an experimental exposure of 1038.4 kg yr. The data reconstruction relies on a simultaneous Bayesian fit applied to energy spectra over a broad energy range. The high granularity of the CUORE detector, together with the large exposure and extended stable operations, allow for an in-depth exploration of both spatial and time dependence of backgrounds. We achieve high sensitivity to both bulk and surface activities of the materials of the setup, detecting levels as low as 10 nBq kg$^{-1}$ and 0.1 nBq cm$^{-2}$, respectively. We compare the contamination levels we extract from the background model with prior radio-assay data, which informs future background risk mitigation strategies. The results of this background model play a crucial role in constructing the background budget for the CUPID experiment as it will exploit the same CUORE infrastructure. △ Less

Submitted 28 May, 2024; originally announced May 2024.

Constraints on Lepton Number Violation with the 2 tonne$\cdot$yr CUORE Dataset

Authors: CUORE Collaboration, D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Beretta, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, A. Campani, J. Cao, S. Capelli, C. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, E. Celi , et al. (93 additional authors not shown)

Abstract: Matter-antimatter asymmetry underlines the incompleteness of the current understanding of particle physics. Neutrinoless double-beta decay ($0νββ$) may help explain this asymmetry, while unveiling the Majorana nature of the neutrino. The CUORE experiment searches for $0νββ$ of $^{130}$Te using a tonne-scale cryogenic calorimeter operated at milli-kelvin temperatures. We report no evidence of… ▽ More Matter-antimatter asymmetry underlines the incompleteness of the current understanding of particle physics. Neutrinoless double-beta decay ($0νββ$) may help explain this asymmetry, while unveiling the Majorana nature of the neutrino. The CUORE experiment searches for $0νββ$ of $^{130}$Te using a tonne-scale cryogenic calorimeter operated at milli-kelvin temperatures. We report no evidence of $0νββ$ and place a lower limit on the half-life of $T_{1/2} >3.5 \times$ 10$^{25}$~years (90\% C.I.) with over 2~tonne$\cdot$year TeO$_2$ exposure. The tools and techniques developed for this result and the 5 year stable operation of nearly 1000 detectors demonstrate crucial infrastructure for a future-generation experiment capable of searching for $0νββ$ across multiple isotopes. △ Less

Submitted 17 October, 2025; v1 submitted 5 April, 2024; originally announced April 2024.

Comments: This is the author's version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science on Oct 16, 2025, DOI:10.1126/science.adp6474

First study of antihyperon-nucleon scattering $\barΛp\rightarrow\barΛp$ and measurement of $Λp\rightarrowΛp$ cross section

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, O. Afedulidis, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, I. Balossino, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere , et al. (634 additional authors not shown)

Abstract: Using $(10.087\pm0.044)\times10^{9}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring, the processes $Λp\rightarrowΛp$ and $\barΛp\rightarrow\barΛp$ are studied, where the $Λ/\barΛ$ baryons are produced in the process $J/ψ\rightarrowΛ\barΛ$ and the protons are the hydrogen nuclei in the cooling oil of the beam pipe. Clear signals are observed for the two reactions. The cr… ▽ More Using $(10.087\pm0.044)\times10^{9}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring, the processes $Λp\rightarrowΛp$ and $\barΛp\rightarrow\barΛp$ are studied, where the $Λ/\barΛ$ baryons are produced in the process $J/ψ\rightarrowΛ\barΛ$ and the protons are the hydrogen nuclei in the cooling oil of the beam pipe. Clear signals are observed for the two reactions. The cross sections in $-0.9\leq\rm{cos}θ_{Λ/\barΛ}\leq0.9$ are measured to be $σ(Λp\rightarrowΛp)=(12.2\pm1.6_{\rm{stat}}\pm1.1_{\rm{sys}})$ mb and $σ(\barΛ p\rightarrow\barΛ p)=(17.5\pm2.1_{\rm{stat}}\pm1.6_{\rm{sys}})$ mb at the $Λ/\barΛ$ momentum of $1.074$ GeV/$c$ within a range of $\pm0.017$ GeV/$c$, where the $θ_{Λ/\barΛ}$ are the scattering angles of the $Λ/\barΛ$ in the $Λp/\barΛp$ rest frames. Furthermore, the differential cross sections of the two reactions are also measured, where there is a slight tendency of forward scattering for $Λp\rightarrowΛp$, and a strong forward peak for $\barΛp\rightarrow\barΛp$. We present an approach to extract the total elastic cross sections by extrapolation. The study of $\barΛp\rightarrow\barΛp$ represents the first study of antihyperon-nucleon scattering, and these new measurements will serve as important inputs for the theoretical understanding of the (anti)hyperon-nucleon interaction. △ Less

Submitted 18 May, 2024; v1 submitted 17 January, 2024; originally announced January 2024.

Comments: 9 pages, 5 figures

Searching for Two-Neutrino and Neutrinoless Double Beta Decay of $^{134}$Xe with the PandaX-4T Experiment

Authors: PandaX Collaboration, Xiyu Yan, Zhaokan Cheng, Abdusalam Abdukerim, Zihao Bo, Wei Chen, Xun Chen, Chen Cheng, Xiangyi Cui, Yingjie Fan, Deqing Fang, Changbo Fu, Mengting Fu, Lisheng Geng, Karl Giboni, Linhui Gu, Xuyuan Guo, Chencheng Han, Ke Han, Changda He, Jinrong He, Di Huang, Yanlin Huang, Junting Huang, Zhou Huang , et al. (72 additional authors not shown)

Abstract: $^{134}$Xe is a candidate isotope for neutrinoless double beta decay~($0νββ$) search. In addition, the two-neutrino case ($2νββ$) allowed by the Standard Model of particle physics has not yet been observed. Utilizing the 10.4% of $^{134}$Xe in the natural xenon in the PandaX-4T detector and its first 94.9-day exposure, we have established the most stringent constraints on $2νββ$ and $0νββ$ of $^{1… ▽ More $^{134}$Xe is a candidate isotope for neutrinoless double beta decay~($0νββ$) search. In addition, the two-neutrino case ($2νββ$) allowed by the Standard Model of particle physics has not yet been observed. Utilizing the 10.4% of $^{134}$Xe in the natural xenon in the PandaX-4T detector and its first 94.9-day exposure, we have established the most stringent constraints on $2νββ$ and $0νββ$ of $^{134}$Xe half-lives, with limits of $2.8\times10^{22}$ yr and $3.0\times10^{23}$ yr at 90% confidence level, respectively. The $2νββ$ ($0νββ$) limit surpasses the previously reported best result by a factor of 32 (2.7), highlighting the potential of large monolithic natural xenon detectors. △ Less

Submitted 28 April, 2024; v1 submitted 25 December, 2023; originally announced December 2023.

Journal ref: Phys.Rev.Lett. 132 (2024) 15, 152502

First measurement of $ΛN$ inelastic scattering with $Λ$ from $e^{+} e^{-} \rightarrow J/ψ\to Λ\barΛ$

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, O. Afedulidis, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, I. Balossino, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere , et al. (626 additional authors not shown)

Abstract: Using an $e^+ e^-$ collision data sample of $(10087 \pm 44)\times10^6 ~J/ψ$ events taken at the center-of-mass energy of $3.097~\rm{GeV}$ by the BESIII detector at the BEPCII collider, the process $Λ+N \rightarrow Σ^+ + X$ is studied for the first time employing a novel method. The $Σ^{+}$ hyperons are produced by the collisions of $Λ$ hyperons from $J/ψ$ decays with nuclei in the material of the… ▽ More Using an $e^+ e^-$ collision data sample of $(10087 \pm 44)\times10^6 ~J/ψ$ events taken at the center-of-mass energy of $3.097~\rm{GeV}$ by the BESIII detector at the BEPCII collider, the process $Λ+N \rightarrow Σ^+ + X$ is studied for the first time employing a novel method. The $Σ^{+}$ hyperons are produced by the collisions of $Λ$ hyperons from $J/ψ$ decays with nuclei in the material of the BESIII detector. The total cross section of $Λ+ ^{9}{\rm Be} \rightarrow Σ^+ + X$ is measured to be $σ= (37.3 \pm 4.7 \pm 3.5)~{\rm mb}$ at $Λ$ beam momenta within $[1.057, 1.091]~{\rm GeV}/c$, where the uncertainties are statistical and systematic, respectively. This analysis is the first study of $Λ$-nucleon interactions at an $e^+ e^-$ collider, providing information and constraints relevant for the strong-interaction potential, the origin of color confinement, the unified model for baryon-baryon interactions, and the internal structure of neutron stars. △ Less

Submitted 1 October, 2023; originally announced October 2023.

Precise determination of $^{210}$Pb $β$ Decay Spectrum at 0 keV and its Implication to Theoretical Calculations

Authors: Shuo Zhang, Xavier Mougeot, Hao-Ran Liu, Ke Han, Tao Sun, Wen-Tao Wu, Robin Cantor, Jing-Kai Xia, Jun-Cheng Liang, Fu-You Fan, Bing-Jun Wu, Le Zhang, Ming-Yu Ge, XiaoPeng Zhou, Zhi Liu

Abstract: The atomic exchange effect will lead to a significant increase in the probability density of $β$ decays below a few keV. This effect is very important for scientific experiments that performed by low-energy electron spectroscopy measurements. However, the atomic exchange effect involves multi-electron interactions, especially for a system with 82 electrons such as lead. Different parameters will l… ▽ More The atomic exchange effect will lead to a significant increase in the probability density of $β$ decays below a few keV. This effect is very important for scientific experiments that performed by low-energy electron spectroscopy measurements. However, the atomic exchange effect involves multi-electron interactions, especially for a system with 82 electrons such as lead. Different parameters will lead to different trends in the energy spectrum predicted by the theory, so it is urgent to carry out experimental measurements to provide parameter limits for the theory. The probability increase brought about by the atomic exchange effect is most obvious near 0keV, and the $β$ energy spectrum is accurately measured near this energy point, so as to provide constraints for the physical model of atomic exchange. However, it is extremely difficult to measure the $β$ energy spectrum at 0keV due to the limitations of electronic noise and internal conversion effects. The excited decay path of $^{210}$Pb was taken as the observation object,by measuring the total energy spectrum of $β$ rays and cascaded gamma rays, the precise measurement of the $β$ energy spectrum near 0keV has been completed. The analysis of the $β$ energy spectrum of $^{210}$Pb gives the following conclusions. The experimental results first verified the theory that the exchange effect causes the probability increase at the low energy end near 0keV. At the same time, the experimental results are higher than the existing predictions of the atomic exchange effect. At least for Pb element, all the electron shells have played a role in improving the probability density of the low end of the $β$ energy spectrum. This discovery will promote the theoretical calculation of the $β$ energy spectrum of $^{214}$Pb, at the same time, it also indicates that the reactor neutrinos have a higher probability density at the omnipotent end. △ Less

Submitted 30 July, 2023; originally announced July 2023.

A first test of CUPID prototypal light detectors with NTD-Ge sensors in a pulse-tube cryostat

Authors: CUPID collaboration, K. Alfonso, A. Armatol, C. Augier, F. T. Avignone III, O. Azzolini, M. Balata, A. S. Barabash, G. Bari, A. Barresi, D. Baudin, F. Bellini, G. Benato, V. Berest, M. Beretta, M. Bettelli, M. Biassoni, J. Billard, V. Boldrini, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Campani, C. Capelli , et al. (154 additional authors not shown)

Abstract: CUPID is a next-generation bolometric experiment aiming at searching for neutrinoless double-beta decay with ~250 kg of isotopic mass of $^{100}$Mo. It will operate at $\sim$10 mK in a cryostat currently hosting a similar-scale bolometric array for the CUORE experiment at the Gran Sasso National Laboratory (Italy). CUPID will be based on large-volume scintillating bolometers consisting of… ▽ More CUPID is a next-generation bolometric experiment aiming at searching for neutrinoless double-beta decay with ~250 kg of isotopic mass of $^{100}$Mo. It will operate at $\sim$10 mK in a cryostat currently hosting a similar-scale bolometric array for the CUORE experiment at the Gran Sasso National Laboratory (Italy). CUPID will be based on large-volume scintillating bolometers consisting of $^{100}$Mo-enriched Li$_2$MoO$_4$ crystals, facing thin Ge-wafer-based bolometric light detectors. In the CUPID design, the detector structure is novel and needs to be validated. In particular, the CUORE cryostat presents a high level of mechanical vibrations due to the use of pulse tubes and the effect of vibrations on the detector performance must be investigated. In this paper we report the first test of the CUPID-design bolometric light detectors with NTD-Ge sensors in a dilution refrigerator equipped with a pulse tube in an above-ground lab. Light detectors are characterized in terms of sensitivity, energy resolution, pulse time constants, and noise power spectrum. Despite the challenging noisy environment due to pulse-tube-induced vibrations, we demonstrate that all the four tested light detectors comply with the CUPID goal in terms of intrinsic energy resolution of 100 eV RMS baseline noise. Indeed, we have measured 70--90 eV RMS for the four devices, which show an excellent reproducibility. We have also obtained outstanding energy resolutions at the 356 keV line from a $^{133}$Ba source with one light detector achieving 0.71(5) keV FWHM, which is -- to our knowledge -- the best ever obtained when compared to $γ$ detectors of any technology in this energy range. △ Less

Submitted 10 April, 2023; originally announced April 2023.

Comments: Prepared for submission to JINST; 16 pages, 7 figures, and 1 table

Twelve-crystal prototype of Li$_2$MoO$_4$ scintillating bolometers for CUPID and CROSS experiments

Authors: CUPID, CROSS collaborations, :, K. Alfonso, A. Armatol, C. Augier, F. T. Avignone III, O. Azzolini, M. Balata, I. C. Bandac, A. S. Barabash, G. Bari, A. Barresi, D. Baudin, F. Bellini, G. Benato, V. Berest, M. Beretta, M. Bettelli, M. Biassoni, J. Billard, V. Boldrini, A. Branca, C. Brofferio, C. Bucci , et al. (160 additional authors not shown)

Abstract: An array of twelve 0.28 kg lithium molybdate (LMO) low-temperature bolometers equipped with 16 bolometric Ge light detectors, aiming at optimization of detector structure for CROSS and CUPID double-beta decay experiments, was constructed and tested in a low-background pulse-tube-based cryostat at the Canfranc underground laboratory in Spain. Performance of the scintillating bolometers was studied… ▽ More An array of twelve 0.28 kg lithium molybdate (LMO) low-temperature bolometers equipped with 16 bolometric Ge light detectors, aiming at optimization of detector structure for CROSS and CUPID double-beta decay experiments, was constructed and tested in a low-background pulse-tube-based cryostat at the Canfranc underground laboratory in Spain. Performance of the scintillating bolometers was studied depending on the size of phonon NTD-Ge sensors glued to both LMO and Ge absorbers, shape of the Ge light detectors (circular vs. square, from two suppliers), in different light collection conditions (with and without reflector, with aluminum coated LMO crystal surface). The scintillating bolometer array was operated over 8 months in the low-background conditions that allowed to probe a very low, $μ$Bq/kg, level of the LMO crystals radioactive contamination by $^{228}$Th and $^{226}$Ra. △ Less

Submitted 10 April, 2023; originally announced April 2023.

Comments: Prepared for submission to JINST; 23 pages, 9 figures, and 4 tables

Measurement of Double Beta Decay Half-life of $^{136}$Xe with the PandaX-4T Detector

Authors: PandaX Collaboration, Lin Si, Zhaokan Cheng, Abdusalam Abdukerim, Zihao Bo, Wei Chen, Xun Chen, Yunhua Chen, Chen Cheng, Yunshan Cheng, Xiangyi Cui, Yingjie Fan, Deqing Fang, Changbo Fu, Mengting Fu, Lisheng Geng, Karl Giboni, Linhui Gu, Xuyuan Guo, Ke Han, Changda He, Jinrong He, Di Huang, Yanlin Huang, Zhou Huang , et al. (63 additional authors not shown)

Abstract: Precise measurement of two-neutrino double beta decay (DBD) half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay. We report the measurement of DBD half-life of $^{136}$Xe using the PandaX-4T dual-phase Time Projection Chamber (TPC) with 3.7-tonne natural xenon and the first 94.9-day physics data release. The background model in the fiducial volu… ▽ More Precise measurement of two-neutrino double beta decay (DBD) half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay. We report the measurement of DBD half-life of $^{136}$Xe using the PandaX-4T dual-phase Time Projection Chamber (TPC) with 3.7-tonne natural xenon and the first 94.9-day physics data release. The background model in the fiducial volume is well constrained in situ by events in the outer active region. With a $^{136}$Xe exposure of 15.5 kg-year, we establish the half-life as $2.27 \pm 0.03 (stat.)\pm 0.10 (syst.)\times 10^{21}$ years. This is the first DBD half-life measurement with natural xenon and demonstrates the physics capability of a large-scale liquid xenon TPC in the field of rare event searches. △ Less

Submitted 12 December, 2022; v1 submitted 25 May, 2022; originally announced May 2022.

Comments: 6 pages, 4 figures

Journal ref: Research, vol. 2022, Article ID 9798721, 2022

An Energy-dependent Electro-thermal Response Model of CUORE Cryogenic Calorimeter

Authors: CUORE Collaboration, D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Beretta, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, A. Campani, L. Canonica, X. G. Cao, S. Capelli, C. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali , et al. (96 additional authors not shown)

Abstract: The Cryogenic Underground Observatory for Rare Events (CUORE) is the most sensitive experiment searching for neutrinoless double-beta decay ($0νββ$) in $^{130}\text{Te}$. CUORE uses a cryogenic array of 988 TeO$_2$ calorimeters operated at $\sim$10 mK with a total mass of 741 kg. To further increase the sensitivity, the detector response must be well understood. Here, we present a non-linear therm… ▽ More The Cryogenic Underground Observatory for Rare Events (CUORE) is the most sensitive experiment searching for neutrinoless double-beta decay ($0νββ$) in $^{130}\text{Te}$. CUORE uses a cryogenic array of 988 TeO$_2$ calorimeters operated at $\sim$10 mK with a total mass of 741 kg. To further increase the sensitivity, the detector response must be well understood. Here, we present a non-linear thermal model for the CUORE experiment on a detector-by-detector basis. We have examined both equilibrium and dynamic electro-thermal models of detectors by numerically fitting non-linear differential equations to the detector data of a subset of CUORE channels which are well characterized and representative of all channels. We demonstrate that the hot-electron effect and electric-field dependence of resistance in NTD-Ge thermistors alone are inadequate to describe our detectors' energy dependent pulse shapes. We introduce an empirical second-order correction factor in the exponential temperature dependence of the thermistor, which produces excellent agreement with energy-dependent pulse shape data up to 6 MeV. We also present a noise analysis using the fitted thermal parameters and show that the intrinsic thermal noise is negligible compared to the observed noise for our detectors. △ Less

Submitted 28 July, 2022; v1 submitted 9 May, 2022; originally announced May 2022.

Comments: 34 pages, 14 figures, 6 tables

New direct limit on neutrinoless double beta decay half-life of $^{128}$Te with CUORE

Authors: D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Beretta, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, A. Campani, L. Canonica, X. G. Cao, C. Capelli, S. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, E. Celi , et al. (95 additional authors not shown)

Abstract: The Cryogenic Underground Observatory for Rare Events (CUORE) at Laboratori Nazionali del Gran Sasso of INFN in Italy is an experiment searching for neutrinoless double beta (0$νββ$) decay. Its main goal is to investigate this decay in $^{130}$Te, but its ton-scale mass and low background make CUORE sensitive to other rare processes as well. In this work, we present our first results on the search… ▽ More The Cryogenic Underground Observatory for Rare Events (CUORE) at Laboratori Nazionali del Gran Sasso of INFN in Italy is an experiment searching for neutrinoless double beta (0$νββ$) decay. Its main goal is to investigate this decay in $^{130}$Te, but its ton-scale mass and low background make CUORE sensitive to other rare processes as well. In this work, we present our first results on the search for \nbb decay of $^{128}$Te, the Te isotope with the second highest natural isotopic abundance. We find no evidence for this decay, and using a Bayesian analysis we set a lower limit on the $^{128}$Te \nbb decay half-life of T$_{1/2} > 3.6 \times 10^{24}$ yr (90\% CI). This represents the most stringent limit on the half-life of this isotope, improving by over a factor 30 the previous direct search results, and exceeding those from geochemical experiments for the first time. △ Less

Submitted 31 January, 2025; v1 submitted 6 May, 2022; originally announced May 2022.

Search for Neutrinoless $β^+EC$ Decay of $^{120}$Te with CUORE

Authors: D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Beretta, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, A. Campani, L. Canonica, X. G. Cao, C. Capelli, S. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, E. Celi , et al. (96 additional authors not shown)

Abstract: CUORE is a large scale cryogenic experiment searching for neutrinoless double beta decay ($0νββ$) in $^{130}$Te. The CUORE detector is made of natural tellurium, providing the possibility of rare event searches on isotopes other than $^{130}$Te. In this work we describe a search for neutrinoless positron emitting electron capture ($0νβ^+EC$) decay in $^{120}$Te with a total TeO$_2$ exposure of 355… ▽ More CUORE is a large scale cryogenic experiment searching for neutrinoless double beta decay ($0νββ$) in $^{130}$Te. The CUORE detector is made of natural tellurium, providing the possibility of rare event searches on isotopes other than $^{130}$Te. In this work we describe a search for neutrinoless positron emitting electron capture ($0νβ^+EC$) decay in $^{120}$Te with a total TeO$_2$ exposure of 355.7 kg $\cdot$ yr, corresponding to 0.2405 kg $\cdot$ yr of $^{120}$Te. Albeit $0 νββ$ with two final state electrons represents the most promising channel, the emission of a positron and two 511-keV $γ$s make $0νβ^+EC$ decay signature extremely clear. To fully exploit the potential offered by the detector modularity we include events with different topology and perform a simultaneous fit of five selected signal signatures. Using blinded data we extract a median exclusion sensitivity of $3.4 \cdot 10^{22}$ yr at 90% Credibility Interval (C.I.). After unblinding we find no evidence of $0νβ^+EC$ signal and set a 90% C.I. Bayesian lower limit of $2.9 \cdot 10^{22}$ yr on $^{120}$Te half-life. This result improves by an order of magnitude the existing limit from the combined analysis of CUORE-0 and Cuoricino. △ Less

Submitted 18 July, 2022; v1 submitted 16 March, 2022; originally announced March 2022.

Toward CUPID-1T

Authors: A. Armatol, C. Augier, F. T. Avignone III, O. Azzolini, M. Balata, K. Ballen, A. S. Barabash, G. Bari, A. Barresi, D. Baudin, F. Bellini, G. Benato, M. Beretta, M. Bettelli, M. Biassoni, J. Billard, V. Boldrini, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, C. Capelli, S. Capelli, L. Cappelli, L. Cardani , et al. (150 additional authors not shown)

Abstract: Current experiments to search for broken lepton-number symmetry through the observation of neutrinoless double-beta decay ($0\mathrm{νββ}$) provide the most stringent limits on the Majorana nature of neutrinos and the effective Majorana neutrino mass ($m_{ββ}$). The next-generation experiments will focus on the sensitivity to the $0\mathrm{νββ}$ half-life of $\mathcal{O}(10^{27}$--$10^{28}$~years… ▽ More Current experiments to search for broken lepton-number symmetry through the observation of neutrinoless double-beta decay ($0\mathrm{νββ}$) provide the most stringent limits on the Majorana nature of neutrinos and the effective Majorana neutrino mass ($m_{ββ}$). The next-generation experiments will focus on the sensitivity to the $0\mathrm{νββ}$ half-life of $\mathcal{O}(10^{27}$--$10^{28}$~years$)$ and $m_{ββ}\lesssim15$~meV, which would provide complete coverage of the so-called Inverted Ordering region of the neutrino mass parameter space. By taking advantage of recent technological breakthroughs, new, future calorimetric experiments at the 1-ton scale can increase the sensitivity by at least another order of magnitude, exploring the large fraction of the parameter space that corresponds to the Normal neutrino mass ordering. In case of a discovery, such experiments could provide important insights toward a new understanding of the mechanism of $0\mathrm{νββ}$. We present here a series of projects underway that will provide advancements in background reduction, cryogenic readout, and physics searches beyond $0\mathrm{νββ}$, all moving toward the next-to-next generation CUPID-1T detector. △ Less

Submitted 8 April, 2022; v1 submitted 16 March, 2022; originally announced March 2022.

Comments: contribution to Snowmass 2021

A Next-Generation Liquid Xenon Observatory for Dark Matter and Neutrino Physics

Authors: J. Aalbers, K. Abe, V. Aerne, F. Agostini, S. Ahmed Maouloud, D. S. Akerib, D. Yu. Akimov, J. Akshat, A. K. Al Musalhi, F. Alder, S. K. Alsum, L. Althueser, C. S. Amarasinghe, F. D. Amaro, A. Ames, T. J. Anderson, B. Andrieu, N. Angelides, E. Angelino, J. Angevaare, V. C. Antochi, D. Antón Martin, B. Antunovic, E. Aprile, H. M. Araújo , et al. (572 additional authors not shown)

Abstract: The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for Weakly Interacting Massive Particles (WIMPs), while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neut… ▽ More The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for Weakly Interacting Massive Particles (WIMPs), while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector. △ Less

Submitted 4 March, 2022; originally announced March 2022.

Comments: 77 pages, 40 figures, 1262 references

Report number: INT-PUB-22-003

Journal ref: J. Phys. G: Nucl. Part. Phys. 50 (2023) 013001

Optimization of the first CUPID detector module

Authors: CUPID collaboration, A. Armatol, C. Augier, F. T. Avignone III, O. Azzolini, M. Balata, K. Ballen, A. S. Barabash, G. Bari, A. Barresi, D. Baudin, F. Bellini, G. Benato, M. Beretta, M. Bettelli, M. Biassoni, J. Billard, V. Boldrini, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, C. Capelli, S. Capelli, L. Cappelli , et al. (153 additional authors not shown)

Abstract: CUPID will be a next generation experiment searching for the neutrinoless double $β$ decay, whose discovery would establish the Majorana nature of the neutrino. Based on the experience achieved with the CUORE experiment, presently taking data at LNGS, CUPID aims to reach a background free environment by means of scintillating Li$_{2}$$^{100}$MoO$_4$ crystals coupled to light detectors. Indeed, the… ▽ More CUPID will be a next generation experiment searching for the neutrinoless double $β$ decay, whose discovery would establish the Majorana nature of the neutrino. Based on the experience achieved with the CUORE experiment, presently taking data at LNGS, CUPID aims to reach a background free environment by means of scintillating Li$_{2}$$^{100}$MoO$_4$ crystals coupled to light detectors. Indeed, the simultaneous heat and light detection allows us to reject the dominant background of $α$ particles, as proven by the CUPID-0 and CUPID-Mo demonstrators. In this work we present the results of the first test of the CUPID baseline module. In particular, we propose a new optimized detector structure and light sensors design to enhance the engineering and the light collection, respectively. We characterized the heat detectors, achieving an energy resolution of (5.9 $\pm$ 0.2) keV FWHM at the $Q$-value of $^{100}$Mo (about 3034 keV). We studied the light collection of the baseline CUPID design with respect to an alternative configuration which features gravity-assisted light detectors' mounting. In both cases we obtained an improvement in the light collection with respect to past measures and we validated the particle identification capability of the detector, which ensures an $α$ particle rejection higher than 99.9%, fully satisfying the requirements for CUPID. △ Less

Submitted 13 February, 2022; originally announced February 2022.

Comments: 10 pages, 5 figures

CUORE Opens the Door to Tonne-scale Cryogenics Experiments

Authors: CUORE Collaboration, D. Q. Adams, C. Alduino, F. Alessandria, K. Alfonso, E. Andreotti, F. T. Avignone III, O. Azzolini, M. Balata, I. Bandac, T. I. Banks, G. Bari, M. Barucci, J. W. Beeman, F. Bellini, G. Benato, M. Beretta, A. Bersani, D. Biare, M. Biassoni, F. Bragazzi, A. Branca, C. Brofferio, A. Bryant, A. Buccheri , et al. (184 additional authors not shown)

Abstract: The past few decades have seen major developments in the design and operation of cryogenic particle detectors. This technology offers an extremely good energy resolution - comparable to semiconductor detectors - and a wide choice of target materials, making low temperature calorimetric detectors ideal for a variety of particle physics applications. Rare event searches have continued to require eve… ▽ More The past few decades have seen major developments in the design and operation of cryogenic particle detectors. This technology offers an extremely good energy resolution - comparable to semiconductor detectors - and a wide choice of target materials, making low temperature calorimetric detectors ideal for a variety of particle physics applications. Rare event searches have continued to require ever greater exposures, which has driven them to ever larger cryogenic detectors, with the CUORE experiment being the first to reach a tonne-scale, mK-cooled, experimental mass. CUORE, designed to search for neutrinoless double beta decay, has been operational since 2017 at a temperature of about 10 mK. This result has been attained by the use of an unprecedentedly large cryogenic infrastructure called the CUORE cryostat: conceived, designed and commissioned for this purpose. In this article the main characteristics and features of the cryogenic facility developed for the CUORE experiment are highlighted. A brief introduction of the evolution of the field and of the past cryogenic facilities are given. The motivation behind the design and development of the CUORE cryogenic facility is detailed as are the steps taken toward realization, commissioning, and operation of the CUORE cryostat. The major challenges overcome by the collaboration and the solutions implemented throughout the building of the cryogenic facility will be discussed along with the potential improvements for future facilities. The success of CUORE has opened the door to a new generation of large-scale cryogenic facilities in numerous fields of science. Broader implications of the incredible feat achieved by the CUORE collaboration on the future cryogenic facilities in various fields ranging from neutrino and dark matter experiments to quantum computing will be examined. △ Less

Submitted 2 December, 2021; v1 submitted 17 August, 2021; originally announced August 2021.

Comments: 45 pages, 14 figures

Journal ref: Prog. Part. Nucl. Phys., 122 (2021), Article 103902

Search for Majorana neutrinos exploiting millikelvin cryogenics with CUORE

Authors: D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Beretta, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, A. Campani, L. Canonica, X. G. Cao, S. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, E. Celi, D. Chiesa , et al. (89 additional authors not shown)

Abstract: The possibility that neutrinos may be their own antiparticles, unique among the known fundamental particles, arises from the symmetric theory of fermions proposed by Ettore Majorana in 1937. Given the profound consequences of such Majorana neutrinos, among which is a potential explanation for the matter-antimatter asymmetry of the universe via leptogenesis, the Majorana nature of neutrinos command… ▽ More The possibility that neutrinos may be their own antiparticles, unique among the known fundamental particles, arises from the symmetric theory of fermions proposed by Ettore Majorana in 1937. Given the profound consequences of such Majorana neutrinos, among which is a potential explanation for the matter-antimatter asymmetry of the universe via leptogenesis, the Majorana nature of neutrinos commands intense experimental scrutiny globally; one of the primary experimental probes is neutrinoless double beta ($0 νββ$) decay. Here we show results from the search for $0 νββ$ decay of $^{130}$Te, using the latest advanced cryogenic calorimeters with the CUORE experiment. CUORE, operating just 10 millikelvin above absolute zero, has pushed the state of the art on three frontiers: the sheer mass held at such ultra-low temperatures, operational longevity, and the low levels of ionising radiation emanating from the cryogenic infrastructure. We find no evidence for $0 νββ$ decay and set a lower bound of $T_{1/2}^{0 ν} > 2.2 \times 10^{25}$ years at a 90% credibility interval. We discuss potential applications of the advances made with CUORE to other fields such as direct dark matter, neutrino and nuclear physics searches and large-scale quantum computing, which can benefit from sustained operation of large payloads in a low-radioactivity, ultra-low temperature cryogenic environment. △ Less

Submitted 11 April, 2022; v1 submitted 14 April, 2021; originally announced April 2021.

Journal ref: Nature 604, 53 (2022)

Search for Double-Beta Decay of $\mathrm{^{130}Te}$ to the $0^+$ States of $\mathrm{^{130}Xe}$ with CUORE

Authors: CUORE Collaboration, D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Biassoni A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, A. Campani, L. Canonica, X. G. Cao, S. Capelli, L. Cappelli, L. Cardani, P. Carniti N. Casali, E. Celi, D. Chiesa M. Clemenza S. Copello, C. Cosmelli, O. Cremonesi , et al. (83 additional authors not shown)

Abstract: The CUORE experiment is a large bolometric array searching for the lepton number violating neutrino-less double beta decay ($0νββ$) in the isotope $\mathrm{^{130}Te}$. In this work we present the latest results on two searches for the double beta decay (DBD) of $\mathrm{^{130}Te}$ to the first $0^{+}_2$ excited state of $\mathrm{^{130}Xe}$: the $0νββ$ decay and the Standard Model-allowed two-neutr… ▽ More The CUORE experiment is a large bolometric array searching for the lepton number violating neutrino-less double beta decay ($0νββ$) in the isotope $\mathrm{^{130}Te}$. In this work we present the latest results on two searches for the double beta decay (DBD) of $\mathrm{^{130}Te}$ to the first $0^{+}_2$ excited state of $\mathrm{^{130}Xe}$: the $0νββ$ decay and the Standard Model-allowed two-neutrinos double beta decay ($2νββ$). Both searches are based on a 372.5 kg$\times$yr TeO$_2$ exposure. The de-excitation gamma rays emitted by the excited Xe nucleus in the final state yield a unique signature, which can be searched for with low background by studying coincident events in two or more bolometers. The closely packed arrangement of the CUORE crystals constitutes a significant advantage in this regard. The median limit setting sensitivities at 90\% Credible Interval (C.I.) of the given searches were estimated as $\mathrm{S^{0ν}_{1/2} = 5.6 \times 10^{24} \: \mathrm{yr}}$ for the ${0νββ}$ decay and $\mathrm{S^{2ν}_{1/2} = 2.1 \times 10^{24} \: \mathrm{yr}}$ for the ${2νββ}$ decay. No significant evidence for either of the decay modes was observed and a Bayesian lower bound at $90\%$ C.I. on the decay half lives is obtained as: $\mathrm{(T_{1/2})^{0ν}_{0^+_2} > 5.9 \times 10^{24} \: \mathrm{yr}}$ for the $0νββ$ mode and $\mathrm{(T_{1/2})^{2ν}_{0^+_2} > 1.3 \times 10^{24} \: \mathrm{yr}}$ for the $2νββ$ mode. These represent the most stringent limits on the DBD of $^{130}$Te to excited states and improve by a factor $\sim5$ the previous results on this process. △ Less

Submitted 30 July, 2021; v1 submitted 26 January, 2021; originally announced January 2021.

Comments: 13 pages, 6 figures

Measurement of the 2$νββ$ Decay Half-life of $^{130}$Te with CUORE

Authors: CUORE Collaboration, D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, A. Campani, L. Canonica, X. G. Cao, S. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, D. Chiesa, M. Clemenza , et al. (88 additional authors not shown)

Abstract: We measured two-neutrino double beta decay of $^{130}$Te using an exposure of 300.7 kg$\cdot$yr accumulated with the CUORE detector. Using a Bayesian analysis to fit simulated spectra to experimental data, it was possible to disentangle all the major background sources and precisely measure the two-neutrino contribution. The half-life is in agreement with past measurements with a strongly reduced… ▽ More We measured two-neutrino double beta decay of $^{130}$Te using an exposure of 300.7 kg$\cdot$yr accumulated with the CUORE detector. Using a Bayesian analysis to fit simulated spectra to experimental data, it was possible to disentangle all the major background sources and precisely measure the two-neutrino contribution. The half-life is in agreement with past measurements with a strongly reduced uncertainty: $T^{2ν}_{1/2} = 7.71^{+0.08}_{-0.06}\mathrm{(stat.)}^{+0.12}_{-0.15}\mathrm{(syst.)}\times10^{20}$ yr. This measurement is the most precise determination of the $^{130}$Te 2$νββ$ decay half-life to date. △ Less

Submitted 19 May, 2021; v1 submitted 21 December, 2020; originally announced December 2020.

Comments: Published in PRL

ACM Class: J.2

Journal ref: Phys. Rev. Lett. 126, 171801 (2021)

Enhanced search sensitivity to the double beta decay of $^{136}$Xe to excited states with topological signatures

Authors: Chen Xie, Kaixiang Ni, Ke Han, Shaobo Wang

Abstract: Double beta decay of $^{136}$Xe to excited states of $^{136}$Ba (DBD-ES) has not yet been discovered experimentally yet. The experimental signature of such decays, one or two gamma rays following the beta signals, can be identified more effectively in a gaseous detector with the help of topological signatures. We have investigated key parameters of particle trajectories of DBD-ES with Monte Carlo… ▽ More Double beta decay of $^{136}$Xe to excited states of $^{136}$Ba (DBD-ES) has not yet been discovered experimentally yet. The experimental signature of such decays, one or two gamma rays following the beta signals, can be identified more effectively in a gaseous detector with the help of topological signatures. We have investigated key parameters of particle trajectories of DBD-ES with Monte Carlo simulation data of the proposed PandaX-III detector as an example. The background rates can be reduced by about one order of magnitude while keeping more than half of signals with topological analysis. The estimated half-life sensitivity of DBD-ES can be improved by 1.8 times to 4.1$\times$10$^{23}$ yr (90\% CL). Similarly, the half-life sensitivity of neutrinoless double beta decay of $^{136}$Xe to excited states of $^{136}$Ba can be improved by a factor of 4.8 with topological signatures. △ Less

Submitted 19 March, 2021; v1 submitted 8 December, 2020; originally announced December 2020.

Characterization of cubic Li$_{2}$$^{100}$MoO$_4$ crystals for the CUPID experiment

Authors: A. Armatol, E. Armengaud, W. Armstrong, C. Augier, F. T. Avignone III, O. Azzolini, A. Barabash, G. Bari, A. Barresi, D. Baudin, F. Bellini, G. Benato, M. Beretta, L. Bergè, M. Biassoni, J. Billard, V. Boldrini, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, S. Capelli, L. Cappelli, L. Cardani, P. Carniti , et al. (147 additional authors not shown)

Abstract: The CUPID Collaboration is designing a tonne-scale, background-free detector to search for double beta decay with sufficient sensitivity to fully explore the parameter space corresponding to the inverted neutrino mass hierarchy scenario. One of the CUPID demonstrators, CUPID-Mo, has proved the potential of enriched Li$_{2}$$^{100}$MoO$_4$ crystals as suitable detectors for neutrinoless double beta… ▽ More The CUPID Collaboration is designing a tonne-scale, background-free detector to search for double beta decay with sufficient sensitivity to fully explore the parameter space corresponding to the inverted neutrino mass hierarchy scenario. One of the CUPID demonstrators, CUPID-Mo, has proved the potential of enriched Li$_{2}$$^{100}$MoO$_4$ crystals as suitable detectors for neutrinoless double beta decay search. In this work, we characterised cubic crystals that, compared to the cylindrical crystals used by CUPID-Mo, are more appealing for the construction of tightly packed arrays. We measured an average energy resolution of (6.7$\pm$0.6) keV FWHM in the region of interest, approaching the CUPID target of 5 keV FWHM. We assessed the identification of $α$ particles with and without a reflecting foil that enhances the scintillation light collection efficiency, proving that the baseline design of CUPID already ensures a complete suppression of this $α$-induced background contribution. We also used the collected data to validate a Monte Carlo simulation modelling the light collection efficiency, which will enable further optimisations of the detector. △ Less

Submitted 27 November, 2020; originally announced November 2020.

New results from the CUORE experiment

Authors: A. Giachero, D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, A. Campani, L. Canonica, X. G. Cao, S. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, E. Celi, D. Chiesa , et al. (88 additional authors not shown)

Abstract: The Cryogenic Underground Observatory for Rare Events (CUORE) is the first cryogenic experiment searching for neutrinoless double-beta ($0νββ$) decay that has been able to reach the one-ton scale. The detector, located at the Laboratori Nazionali del Gran Sasso in Italy, consists of an array of 988 TeO$_2$ crystals arranged in a compact cylindrical structure of 19 towers. Following the completion… ▽ More The Cryogenic Underground Observatory for Rare Events (CUORE) is the first cryogenic experiment searching for neutrinoless double-beta ($0νββ$) decay that has been able to reach the one-ton scale. The detector, located at the Laboratori Nazionali del Gran Sasso in Italy, consists of an array of 988 TeO$_2$ crystals arranged in a compact cylindrical structure of 19 towers. Following the completion of the detector construction in August 2016, CUORE began its first physics data run in 2017 at a base temperature of about 10 mK. Following multiple optimization campaigns in 2018, CUORE is currently in stable operating mode. In 2019, CUORE released its 2\textsuperscript{nd} result of the search for $0νββ$ with a TeO$_2$ exposure of 372.5 kg$\cdot$yr and a median exclusion sensitivity to a $^{130}$Te $0νββ$ decay half-life of $1.7\cdot 10^{25}$ yr. We find no evidence for $0νββ$ decay and set a 90\% C.I. (credibility interval) Bayesian lower limit of $3.2\cdot 10^{25}$ yr on the $^{130}$Te $0νββ$ decay half-life. In this work, we present the current status of CUORE's search for $0νββ$, as well as review the detector performance. Finally, we give an update of the CUORE background model and the measurement of the $^{130}$Te two neutrino double-beta ($2νββ$) decay half-life. △ Less

Submitted 7 January, 2021; v1 submitted 18 November, 2020; originally announced November 2020.

Comments: Proceeding of 40th International Conference on High Energy physics (ICHEP2020), July 28 - August 6, 2020, Prague, Czech Republic (virtual meeting). arXiv admin note: text overlap with arXiv:1905.07667

Internal Calibration of the PandaX-II Detector with Radon Gaseous Sources

Authors: Wenbo Ma, Abdusalam Abdukerim, Zihao Bo, Wei Chen, Xun Chen, Yunhua Chen, Chen Cheng, Xiangyi Cui, Yingjie Fan, Deqing Fang, Changbo Fu, Mengting Fu, Lisheng Geng, Karl Giboni, Linhui Gu, Xuyuan Guo, Ke Han, Changda He, Shengming He, Di Huang, Yan Huang, Yanlin Huang, Zhou Huang, Xiangdong Ji, Yonglin Ju , et al. (43 additional authors not shown)

Abstract: We have developed a low-energy electron recoil (ER) calibration method with $^{220}$Rn for the PandaX-II detector. $^{220}$Rn, emanated from natural thorium compounds, was fed into the detector through the xenon purification system. From 2017 to 2019, we performed three dedicated calibration campaigns with different radon sources. We studied the detector response to $α$, $β$, and $γ$ particles wit… ▽ More We have developed a low-energy electron recoil (ER) calibration method with $^{220}$Rn for the PandaX-II detector. $^{220}$Rn, emanated from natural thorium compounds, was fed into the detector through the xenon purification system. From 2017 to 2019, we performed three dedicated calibration campaigns with different radon sources. We studied the detector response to $α$, $β$, and $γ$ particles with focus on low energy ER events. During the runs in 2017 and 2018, the amount of radioactivity of $^{222}$Rn were on the order of 1\% of that of $^{220}$Rn and thorium particulate contamination was negligible, especially in 2018. We also measured the background contribution from $^{214}$Pb for the first time in PandaX-II with the help from a $^{222}$Rn injection. Calibration strategy with $^{220}$Rn and $^{222}$Rn will be implemented in the upcoming PandaX-4T experiment and can be useful for other xenon-based detectors as well. △ Less

Submitted 4 January, 2021; v1 submitted 16 June, 2020; originally announced June 2020.

Comments: 14 pages, 8 figures. published in JINST

Journal ref: JINST 15 P12038 (2020)

Improved Limit on Neutrinoless Double-Beta Decay in $^{130}$Te with CUORE

Authors: CUORE Collaboration, D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, A. Caminata, A. Campani, L. Canonica, X. G. Cao, S. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, D. Chiesa, N. Chott, M. Clemenza , et al. (86 additional authors not shown)

Abstract: We report new results from the search for neutrinoless double-beta decay in $^{130}$Te with the CUORE detector. This search benefits from a four-fold increase in exposure, lower trigger thresholds and analysis improvements relative to our previous results. We observe a background of $(1.38\pm0.07)\cdot10^{-2}$ counts$/($keV$\cdot$kg$\cdot$yr$)$ in the $0νββ$ decay region of interest and, with a to… ▽ More We report new results from the search for neutrinoless double-beta decay in $^{130}$Te with the CUORE detector. This search benefits from a four-fold increase in exposure, lower trigger thresholds and analysis improvements relative to our previous results. We observe a background of $(1.38\pm0.07)\cdot10^{-2}$ counts$/($keV$\cdot$kg$\cdot$yr$)$ in the $0νββ$ decay region of interest and, with a total exposure of 372.5 kg$\cdot$yr, we attain a median exclusion sensitivity of $1.7\cdot10^{25}$ yr. We find no evidence for $0νββ$ decay and set a $90\%$ CI Bayesian lower limit of $3.2\cdot10^{25}$ yr on the $^{130}$Te half-life for this process. In the hypothesis that $0νββ$ decay is mediated by light Majorana neutrinos, this results in an upper limit on the effective Majorana mass of 75-350 meV, depending on the nuclear matrix elements used. △ Less

Submitted 23 December, 2019; originally announced December 2019.

Comments: 7 pages, 5 figures

An Improved Evaluation of the Neutron Background in the PandaX-II Experiment

Authors: Qiuhong Wang, Abdusalam Abdukerim, Wei Chen, Xun Chen, Yunhua Chen, Xiangyi Cui, Yingjie Fan, Deqing Fang, Changbo Fu, Lisheng Geng, Karl Giboni, Franco Giuliani, Linhui Gu, Xuyuan Guo, Ke Han, Changda He, Di Huang, Yan Huang, Yanlin Huang, Zhou Huang, Peng Ji, Xiangdong Ji, Yonglin Ju, Yihui Lai, Kun Liang , et al. (38 additional authors not shown)

Abstract: In dark matter direct detection experiments, neutron is a serious source of background, which can mimic the dark matter-nucleus scattering signals. In this paper, we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach. Instead of fully relying on the Monte Carlo simulation, the overall neutron background is determined from the neutro… ▽ More In dark matter direct detection experiments, neutron is a serious source of background, which can mimic the dark matter-nucleus scattering signals. In this paper, we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach. Instead of fully relying on the Monte Carlo simulation, the overall neutron background is determined from the neutron-induced high energy signals in the data. In addition, the probability of producing a dark-matter-like background per neutron is evaluated with a complete Monte Carlo generator, where the correlated emission of neutron(s) and $γ$(s) in the ($α$, n) reactions and spontaneous fissions is taken into consideration. With this method, the neutron backgrounds in the Run 9 (26-ton-day) and Run 10 (28-ton-day) data sets of PandaX-II are estimated to be 0.66$\pm$0.24 and 0.47$\pm$0.25 events, respectively. △ Less

Submitted 24 July, 2019; v1 submitted 1 July, 2019; originally announced July 2019.

Comments: 9 pages, 9 figures, 7 tables; version2 accepted by Sci. China Phys. Mech. Astron

Journal ref: Sci.China Phys.Mech.Astron. 63 (2020) 3, 231011

Searching for Neutrino-less Double Beta Decay of $^{136}$Xe with PandaX-II Liquid Xenon Detector

Authors: Kaixiang Ni, Yihui Lai, Abdusalam Abdukerim, Wei Chen, Xun Chen, Yunhua Chen, Xiangyi Cui, Yingjie Fan, Deqing Fang, Changbo Fu, Lisheng Geng, Karl Giboni, Franco Giuliani, Linhui Gu, Xuyuan Guo, Ke Han, Changda He, Di Huang, Yan Huang, Yanlin Huang, Zhou Huang, Peng Ji, Xiangdong Ji, Yonglin Ju, Kun Liang , et al. (38 additional authors not shown)

Abstract: We report the Neutrino-less Double Beta Decay (NLDBD) search results from PandaX-II dual-phase liquid xenon time projection chamber. The total live time used in this analysis is 403.1 days from June 2016 to August 2018. With NLDBD-optimized event selection criteria, we obtain a fiducial mass of 219 kg of natural xenon. The accumulated xenon exposure is 242 kg$\cdot$yr, or equivalently 22.2 kg… ▽ More We report the Neutrino-less Double Beta Decay (NLDBD) search results from PandaX-II dual-phase liquid xenon time projection chamber. The total live time used in this analysis is 403.1 days from June 2016 to August 2018. With NLDBD-optimized event selection criteria, we obtain a fiducial mass of 219 kg of natural xenon. The accumulated xenon exposure is 242 kg$\cdot$yr, or equivalently 22.2 kg$\cdot$yr of $^{136}$Xe exposure. At the region around $^{136}$Xe decay Q-value of 2458 keV, the energy resolution of PandaX-II is 4.2%. We find no evidence of NLDBD in PandaX-II and establish a lower limit for decay half-life of 2.4 $ \times 10^{23} $ yr at the 90% confidence level, which corresponds to an effective Majorana neutrino mass $m_{ββ} < (1.3 - 3.5)$ eV. This is the first NLDBD result reported from a dual-phase xenon experiment. △ Less

Submitted 27 June, 2019; originally announced June 2019.

Comments: Submitted to Chinese Physics C

Results of CUORE

Authors: S. Dell'Oro, D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, A. Caminata, A. Campani, L. Canonica, X. G. Cao, S. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, D. Chiesa, N. Chott, M. Clemenza , et al. (87 additional authors not shown)

Abstract: The Cryogenic Underground Observatory for Rare Events (CUORE) at the Laboratori Nazionali del Gran Sasso, Italy, is the world's largest bolometric experiment. The detector consists of an array of 988 TeO2 crystals, for a total mass of 742 kg. CUORE is presently in data taking, searching for the neutrinoless double beta decay of 130 Te. CUORE is operational since the spring of 2017. The initial sci… ▽ More The Cryogenic Underground Observatory for Rare Events (CUORE) at the Laboratori Nazionali del Gran Sasso, Italy, is the world's largest bolometric experiment. The detector consists of an array of 988 TeO2 crystals, for a total mass of 742 kg. CUORE is presently in data taking, searching for the neutrinoless double beta decay of 130 Te. CUORE is operational since the spring of 2017. The initial science run already allowed to provide the most stringent limit on the neutrinoless double beta decay half-life of 130Te, and to perform the most precise measurement of the two-neutrino double beta decay half-life. Up to date, we have more than doubled the collected exposure. In this talk, we presenteded the most recent results and discuss the present status of the CUORE experiment. △ Less

Submitted 18 May, 2019; originally announced May 2019.

Comments: contribution to the 2019 EW/QCD/Gravitation session of the 54th Rencontres de Moriond

Double-beta decay of ${}^{130}$Te to the first $0^+$ excited state of ${}^{130}$Xe with CUORE-0

Authors: CUORE Collaboration, C. Alduino, K. Alfonso, D. R. Artusa, F. T. Avignone III, O. Azzolini, T. I. Banks, G. Bari, J. W. Beeman, F. Bellini, A. Bersani, M. Biassoni, C. Brofferio, C. Bucci, A. Caminata, L. Canonica, X. G. Cao, S. Capelli, L. Cappelli, L. Carbone, L. Cardani, P. Carniti, N. Casali, L. Cassina, D. Chiesa , et al. (96 additional authors not shown)

Abstract: We report on a search for double beta decay of $^{130}$Te to the first $0^{+}$ excited state of $^{130}$Xe using a 9.8 kg$\cdot$yr exposure of $^{130}$Te collected with the CUORE-0 experiment. In this work we exploit different topologies of coincident events to search for both the neutrinoless and two-neutrino double-decay modes. We find no evidence for either mode and place lower bounds on the ha… ▽ More We report on a search for double beta decay of $^{130}$Te to the first $0^{+}$ excited state of $^{130}$Xe using a 9.8 kg$\cdot$yr exposure of $^{130}$Te collected with the CUORE-0 experiment. In this work we exploit different topologies of coincident events to search for both the neutrinoless and two-neutrino double-decay modes. We find no evidence for either mode and place lower bounds on the half-lives: $τ^{0ν}_{0^+}>7.9\cdot 10^{23}$ yr and $τ^{2ν}_{0^+}>2.4\cdot 10^{23}$ yr. Combining our results with those obtained by the CUORICINO experiment, we achieve the most stringent constraints available for these processes: $τ^{0ν}_{0^+}>1.4\cdot 10^{24}$ yr and $τ^{2ν}_{0^+}>2.5\cdot 10^{23}$ yr. △ Less

Submitted 29 November, 2018; v1 submitted 26 November, 2018; originally announced November 2018.

Comments: 9 pages, 5 figures, 5 tables

Journal ref: Eur. Phys. J. C 79, 795 (2019)

Update on the recent progress of the CUORE experiment

Authors: CUORE Collaboration, D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, A. Bersani, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, A. Caminata, A. Campani, L. Canonica, X. G. Cao, S. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, L. Cassina, D. Chiesa , et al. (96 additional authors not shown)

Abstract: CUORE is a 741 kg array of 988 TeO$_2$ bolometeric crystals designed to search for the neutrinoless double beta decay of $^{130}$Te and other rare processes. CUORE has been taking data since summer 2017, and as of summer 2018 collected a total of 86.3 kg$\cdot$yr of TeO$_2$ exposure. Based on this exposure, we were able to set a limit on the $0νββ$ half-life of $^{130}$Te of… ▽ More CUORE is a 741 kg array of 988 TeO$_2$ bolometeric crystals designed to search for the neutrinoless double beta decay of $^{130}$Te and other rare processes. CUORE has been taking data since summer 2017, and as of summer 2018 collected a total of 86.3 kg$\cdot$yr of TeO$_2$ exposure. Based on this exposure, we were able to set a limit on the $0νββ$ half-life of $^{130}$Te of $T^{0ν}_{1/2}>1.5\times10^{25}$ yr at 90% C.L. At this conference, we showed the decomposition of the CUORE background and were able to extract a $^{130}$Te $2νββ$ half-life of $T_{1/2}^{2ν}=[7.9\pm0.1 \mathrm{(stat.)}\pm0.2 \mathrm{(syst.)}]\times10^{20}$ yr. This is the most precise measurement of this half-life and is consistent with previous measurements. △ Less

Submitted 30 August, 2018; originally announced August 2018.

Comments: Proceedings of the Neutrino 2018 Conference. 8 pages, 7 figures

Signal-background discrimination with convolutional neural networks in the PandaX-III experiment using MC simulation

Authors: Hao Qiao, Chunyu Lu, Xun Chen, Ke Han, Xiangdong Ji, Siguang Wang

Abstract: The PandaX-III experiment will search for neutrinoless double beta decay of $^{136}$Xe with high pressure gaseous time projection chambers at the China Jin-Ping underground Laboratory. The tracking feature of gaseous detectors helps suppress the background level, resulting in the improvement of the detection sensitivity. We study a method based on the convolutional neural networks to discriminate… ▽ More The PandaX-III experiment will search for neutrinoless double beta decay of $^{136}$Xe with high pressure gaseous time projection chambers at the China Jin-Ping underground Laboratory. The tracking feature of gaseous detectors helps suppress the background level, resulting in the improvement of the detection sensitivity. We study a method based on the convolutional neural networks to discriminate double beta decay signals against the background from high energy gammas generated by $^{214}$Bi and $^{208}$Tl decays based on detailed Monte Carlo simulation. Using the 2-dimensional projections of recorded tracks on two planes, the method successfully suppresses the background level by a factor larger than 100 with a high signal efficiency. An improvement of $62\%$ on the efficiency ratio of $ε_{s}/\sqrt{ε_{b}}$ is achieved in comparison with the baseline in the PandaX-III conceptual design report. △ Less

Submitted 12 August, 2018; v1 submitted 9 February, 2018; originally announced February 2018.

Comments: version accepted by SCPMA, 11 pages, 10 figures and 4 tables

Study of Rare Nuclear Processes with CUORE

Authors: CUORE Collaboration, C. Alduino, K. Alfonso, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G. Benato, A. Bersani, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, A. Caminata, A. Campani, L. Canonica, X. G. Cao, S. Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, L. Cassina, D. Chiesa, N. Chott , et al. (94 additional authors not shown)

Abstract: TeO2 bolometers have been used for many years to search for neutrinoless double beta decay in 130-Te. CUORE, a tonne-scale TeO2 detector array, recently published the most sensitive limit on the half-life, $T_{1/2}^{0ν} > 1.5 \times 10^{25}\,$yr, which corresponds to an upper bound of $140-400$~meV on the effective Majorana mass of the neutrino. While it makes CUORE a world-leading experiment look… ▽ More TeO2 bolometers have been used for many years to search for neutrinoless double beta decay in 130-Te. CUORE, a tonne-scale TeO2 detector array, recently published the most sensitive limit on the half-life, $T_{1/2}^{0ν} > 1.5 \times 10^{25}\,$yr, which corresponds to an upper bound of $140-400$~meV on the effective Majorana mass of the neutrino. While it makes CUORE a world-leading experiment looking for neutrinoless double beta decay, it is not the only study that CUORE will contribute to in the field of nuclear and particle physics. As already done over the years with many small-scale experiments, CUORE will investigate both rare decays (such as the two-neutrino double beta decay of 130-Te and the hypothesized electron capture in 123-Te), and rare processes (e.g., dark matter and axion interactions). This paper describes some of the achievements of past experiments that used TeO2 bolometers, and perspectives for CUORE. △ Less

Submitted 17 January, 2018; v1 submitted 16 January, 2018; originally announced January 2018.

Comments: 36 pages, 13 figures, sumbitted to IJMPA Special Issue "Results and Developments in the investigation of rare nuclear decays and processes"