Ядерна фізика та енергетика Nuclear Physics and Atomic Energy   ISSN: 1818-331X (Print), 2074-0565 (Online)   Publisher: Institute for Nuclear Research of the National Academy of Sciences of Ukraine   Languages: Ukrainian, English   Periodicity: 4 times per year   Open access peer reviewed journal

Full text (en)

P. Belli^1,2, R. Bernabei^1,2,*, F. Cappella^3,4, V. Caracciolo^1,2, R. Cerulli^1,2, F. A. Danevich^2,5, A. Inchicchitti^3,4, D. V. Kasperovych⁵, V. R. Klavdiienko⁵, V. V. Kobychev⁵, A. Leoncini^1,2, V. Merlo^1,2, O. G. Polischuk^3,5, V. I. Tretyak<sup>5,6

1</sup> Department of Physics, University of Rome "Tor Vergata", Rome, Italy
² National Institute for Nuclear Physics, Rome Section “Tor Vergata”, Rome, Italy
³ National Institute for Nuclear Physics, Rome Section, Rome, Italy
⁴ Department of Physics, University of Rome "La Sapienza", Rome, Italy
⁵ Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kyiv, Ukraine
⁶ National Institute for Nuclear Physics, Gran Sasso National Laboratory, Assergi, Italy

^*Corresponding author. E-mail address: rita.bernabei@roma2.infn.it

Abstract: An experiment to search for 2ε-, εβ⁺- and 2β⁺-decays of ¹⁰⁶Cd, using a 215 g cadmium tungstate scintillation crystal enriched at 66 % by ¹⁰⁶Cd (¹⁰⁶CdWO₄) is carried out at the Gran Sasso underground laboratory (Italy). Events in the ¹⁰⁶CdWO₄ detector are recorded in (anti)coincidences with two large-volume CdWO₄ scintillation counters. The design of the detector system, calibration and background measurements, methods, and results of data analysis to determine key detector characteristics are described. The experimental data are compared with Monte Carlo simulation results, and a background model is constructed. The radioactive contamination of the setup components is studied. The sensitivity of the experiment approaches the level of theoretical predictions for the 2νεβ⁺-decay channel, while for other possible 2β-decay channels it is already on the level of lim T_1/2 ∼ 10²¹-10²² years.

Keywords: ¹⁰⁶Cd, double beta decay, 2ε, εβ⁺, 2β⁺, low background, scintillation detector.

1. A. Giuliani, A. Poves. Neutrinoless Double-Beta Decay. AHEP 2012 (2012) 857016. https://doi.org/10.1155/2012/857016

2. M. Agostini et al. Toward the discovery of matter creation with neutrinoless double-beta decay. Rev. Mod. Phys. 95 (2023) 025002. https://doi.org/10.1103/RevModPhys.95.025002

3. O. Cremonesi, M. Pavan. Challenges in Double Beta Decay. AHEP 2014 (2014) 951432. https://doi.org/10.1155/2014/951432

4. E. Bossio, M. Agostini. Probing Beyond the Standard Model Physics with Double-beta Decays. arXiv:2304.07198v1 [hep-ex] (2023). https://doi.org/10.48550/arXiv.2304.07198

5. S.M. Bilenky, C. Giunti. Neutrinoless double-beta decay: A probe of physics beyond the Standard Model. Int. J. Mod. Phys. A 30 (2015) 1530001. https://doi.org/10.1142/S0217751X1530001X

6. S. Dell'Oro et al. Neutrinoless Double Beta Decay: 2015 Review. AHEP 2016 (2016) 2162659. https://doi.org/10.1155/2016/2162659

7. M.J. Dolinski, A.W.P. Poon, W. Rodejohann. Neutrinoless double beta decay: Status and prospects. Annu. Rev. Nucl. Part. Sci. 69 (2019) 219. https://doi.org/10.1146/annurev-nucl-101918-023407

8. T. Asaka, M. Shaposhnikov. The νMSM, dark matter and baryon asymmetry of the universe. Phys. Lett. B 620 (2005) 17. https://doi.org/10.1016/j.physletb.2005.06.020

9. F.F. Deppisch et al. Neutrinoless double beta decay and the baryon asymmetry of the Universe. Phys. Rev. D 98 (2018) 055029. https://doi.org/10.1103/PhysRevD.98.055029

10. A.S. Barabash. Precise Half-Life Values for Two-Neutrino Double-β Decay: 2020 Review. Universe 6 (2020) 159. https://doi.org/10.3390/universe6100159

11. R. Saakyan. Two-Neutrino Double-Beta Decay. Annu. Rev. Nucl. Part. Sci. 63 (2013) 503. https://doi.org/10.1146/annurev-nucl-102711-094904

12. A.P. Meshik et al. Weak decay of ¹³⁰Ba and ¹³²Ba: Geochemical measurements. Phys. Rev. C 64 (2001) 035205. https://doi.org/10.1103/PhysRevC.64.035205

13. M. Pujol et al. Xenon in Archean barite: Weak decay of ¹³⁰Ba, mass-dependent isotopic fractionation and implication for barite formation. Geochim. Cosmochim. Acta 73 (2009) 6834. https://doi.org/10.1016/j.gca.2009.08.002

14. Yu.M. Gavrilyuk et al. Indications of 2ν2K capture in ⁷⁸Kr. Phys. Rev. C 87 (2013) 035501. https://doi.org/10.1103/PhysRevC.87.035501

15. S.S. Ratkevich et al. Comparative study of the double-K-shell-vacancy production in single- and double-electron-capture decay. Phys. Rev. C 96 (2017) 065502. https://doi.org/10.1103/PhysRevC.96.065502

16. E. Aprile et al. (XENON Collaboration). Search for new physics in electronic recoil data from XENONnT. Phys. Rev. Lett. 129 (2022) 161805. https://doi.org/10.1103/PhysRevLett.129.161805

17. P. Belli et al. Search for double-β decay processes in ¹⁰⁶Cd with the help of a ¹⁰⁶CdWO₄ crystal scintillator. Phys. Rev. C 85 (2012) 044610. https://doi.org/10.1103/PhysRevC.85.044610

18. M. Wang et al. The AME2020 atomic mass evaluation (II). Tables, graphs and references. Chin. Phys. C 45 (2021) 030003. https://doi.org/10.1088/1674-1137/abddaf

19. J. Meija et al. Isotopic composition of the elements 2013. (IUPAC Technical Report). Pure Appl. Chem. 88 (2016) 293. https://doi.org/10.1515/pac-2015-0503

20. P. Belli et al. Development of enriched ¹⁰⁶CdWO₄ crystal scintillators to search for double β decay processes in ¹⁰⁶Cd. Nucl. Instrum. Meth. A 615 (2010) 301. https://doi.org/10.1016/j.nima.2010.01.081

21. P. Belli et al. Search for 2β decay in ¹⁰⁶Cd with an enriched ¹⁰⁶CdWO₄ crystal scintillator in coincidence with four HPGe detectors. Phys. Rev. C 93 (2016) 045502. https://doi.org/10.1103/PhysRevC.93.045502

22. P. Belli et al. Search for Double Beta Decay of ¹⁰⁶Cd with an Enriched ¹⁰⁶CdWO₄ Crystal Scintillator in Coincidence with CdWO₄ Scintillation Counters. Universe 6 (2020) 182. https://doi.org/10.3390/universe6100182

23. D. De Frenne, A. Negret. Nuclear data sheets for A = 106. Nucl. Data Sheets 109 (2008) 943. https://doi.org/10.1016/j.nds.2008.03.002

24. R. Bernabei et al. First results from DAMA/LIBRA and the combined results with DAMA/NaI. Eur. Phys. J. C 56 (2008) 333. https://doi.org/10.1140/epjc/s10052-008-0662-y

25. X. Mougeot. Reliability of usual assumptions in the calculation of β and ν spectra. Phys. Rev. C 91 (2015) 055504. https://doi.org/10.1103/PhysRevC.91.055504

26. H. Primakoff, S.P. Rosen. Double beta decay. Rep. Prog. Phys. 22 (1959) 121. https://doi.org/10.1088/0034-4885/22/1/305

27. L. Cadamuro et al. Characterization of the Hamamatsu R11265-103-M64 multi-anode photomultiplier tube. Journal of Instrumentation 9 (2014) 06021. https://doi.org/10.1088/1748-0221/9/06/P06021

28. M. Calvi et al. Characterization of the Hamamatsu H12700A-03 and R12699-03 multi-anode photomultiplier tubes. Journal of Instrumentation 10 (2015) 09021. https://doi.org/10.1088/1748-0221/10/09/P09021

29. L.T. Tsankov, M.G. Mitev. Response of a NaI(Tl) scintillation detector in a wide temperature interval. Proceedings of the Technical University - Sofia 56(1) (2006) 160. https://www.researchgate.net/publication/228563928_Response_of_a_NaI_Tl_scintillation_detector_in_a_wide_temperature_interval

30. I. Kawrakow et al. The EGSnrc Code System: Monte Carlo Simulation of Electron and Photon Transport. NRCC Report PIRS-701 (Ottawa, Canada, National Research Council of Canada, 2003) 323 p. https://nrc-cnrc.github.io/EGSnrc/doc/pirs701-egsnrc.pdf

31. E. Gatti, F. De Martini. A new linear method of discrimination between elementary particles in scintillation counters. In: Nuclear Electronics. Vol. II. Proc. of the Conf. on Nuclear Electronics, Belgrade, 15 - 20 May 1961 (Vienna, IAEA, 1962) p. 265. https://inis.iaea.org/collection/NCLCollectionStore/_Public/43/116/43116625.pdf

32. F.A. Danevich et al. Search for 2β decay of cadmium and tungsten isotopes: Final results of the Solotvina experiment. Phys. Rev. C 68 (2003) 035501. https://doi.org/10.1103/PhysRevC.68.035501

33. V.I. Tretyak. Semi-empirical calculation of quenching factors for ions in scintillators. Astropart. Phys. 33 (2010) 40. https://doi.org/10.1016/j.astropartphys.2009.11.002

34. R.B. Firestone, C.M. Baglin, S.Y. Frank Chu. Table of Isotopes. 8th ed. (New York, John Wiley, 1996) and CD update (1998). https://www.wiley.com/en-dk/Table+of+Isotopes:+1999+Update,+8th+Edition-p-9780471356332

35. F.A. Danevich et al. α activity of natural tungsten isotopes. Phys. Rev. C 67 (2003) 014310. https://doi.org/10.1103/PhysRevC.67.014310

36. A.S. Barabash et al. Final results of the Aurora experiment to study 2β decay of ¹¹⁶Cd with enriched ¹¹⁶CdWO₄ crystal scintillators. Phys. Rev. D 98 (2018) 092007. https://doi.org/10.1103/PhysRevD.98.092007

37. O.A. Ponkratenko, V.I. Tretyak, Y.G. Zdesenko. Event generator DECAY4 for simulating double-beta processes and decays of radioactive nuclei. Phys. Atom. Nucl. 63 (2000) 1282. https://doi.org/10.1134/1.855784

38. G.J. Feldman, R.D. Cousins. Unified approach to the classical statistical analysis of small signals. Phys. Rev. D 57 (1998) 3873. https://doi.org/10.1103/PhysRevD.57.3873