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Gomez-Cadenas, J. J., Martin-Albo, J., Menendez, J., Mezzetto, M., Monrabal, F., & Sorel, M. (2024). The search for neutrinoless double-beta decay. Riv. Nuovo Cimento, 46, 619–692.
Abstract: Neutrinos are the only particles in the Standard Model that could be Majorana fermions, that is, completely neutral fermions that are their own antiparticles. The most sensitive known experimental method to verify whether neutrinos are Majorana particles is the search for neutrinoless double-beta decay. The last 2 decades have witnessed the development of a vigorous program of neutrinoless double-beta decay experiments, spanning several isotopes and developing different strategies to handle the backgrounds masking a possible signal. In addition, remarkable progress has been made in the understanding of the nuclear matrix elements of neutrinoless double-beta decay, thus reducing a substantial part of the theoretical uncertainties affecting the particle-physics interpretation of the process. On the other hand, the negative results by several experiments, combined with the hints that the neutrino mass ordering could be normal, may imply very long lifetimes for the neutrinoless double-beta decay process. In this report, we review the main aspects of such process, the recent progress on theoretical ideas and the experimental state of the art. We then consider the experimental challenges to be addressed to increase the sensitivity to detect the process in the likely case that lifetimes are much longer than currently explored, and discuss a selection of the most promising experimental efforts.
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Baeza-Ballesteros, J., Donini, A., Molina-Terriza, G., Monrabal, F., & Simon, A. (2024). Towards a realistic setup for a dynamical measurement of deviations from Newton's 1/r2 law: the impact of air viscosity. Eur. Phys. J. C, 84(6), 596–20pp.
Abstract: A novel experimental setup to measure deviations from the 1/r(2) distance dependence of Newtonian gravity was proposed in Donini and Marimon (Eur Phys J C 76:696, 2016). The underlying theoretical idea was to study the orbits of a microscopically-sized planetary system composed of a “Satellite”, with mass m(S) similar to O(10-9) g, and a “Planet”, with mass M-P similar to O(10-5) g at an initial distance of hundreds of microns. The detection of precession of the orbit in this system would be an unambiguous indication of a central potential with terms that scale with the distance differently from 1/r. This is a huge advantage with respect to the measurement of the absolute strength of the attraction between two bodies, as most electrically-induced background potentials do indeed scale as 1/r. Detection of orbit precession is unaffected by these effects, allowing for better sensitivities. In Baeza-Ballesteros et al. (Eur Phys J C 82:154, 2022), the impact of other subleading backgrounds that may induce orbit precession, such as, e.g., the electrical Casimir force or general relativity, was studied in detail. It was found that the proposed setup could test Yukawa-like corrections, alpha x exp(-r/lambda), to the 1/r potential with couplings as low as alpha similar to 10(-2) for distances as small as lambda similar to 10 μm, improving by roughly an order of magnitude present bounds. In this paper, we start to move from a theoretical study of the proposal to a more realistic implementation of the experimental setup. As a first step, we study the impact of air viscosity on the proposed setup and see how the setup should be modified in order to preserve the theoretical sensitivity achieved in Donini and Marimon (2016) and Baeza-Ballesteros et al. (2022).
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Gil, A., Diaz, J., Gomez-Cadenas, J. J., Herrero, V., Rodriguez, J., Serra, L., et al. (2012). Front-end electronics for accurate energy measurement of double beta decays. Nucl. Instrum. Methods Phys. Res. A, 695, 407–409.
Abstract: NEXT, a double beta decay experiment that will operate in Canfranc Underground Laboratory (Spain), aims at measuring the neutrinoless double-beta decay of the 136Xe isotope using a TPC filled with enriched Xenon gas at high pressure operated in electroluminescence mode. One technological challenge of the experiment is to achieve resolution better than 1% in the energy measurement using a plane of UV sensitive photomultipliers readout with appropriate custom-made front-end electronics. The front-end is designed to be sensitive to the single photo-electron to detect the weak primary scintillation light produced in the chamber, and also to be able to cope with the electroluminescence signal (several hundred times higher and with a duration of microseconds). For efficient primary scintillation detection and precise energy measurement of the electroluminescent signals the front-end electronics features low noise and adequate amplification. The signal shaping provided allows the digitization of the signals at a frequency as low as 40 MHz.
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Baxter, D., Collar, J. I., Coloma, P., Dahl, C. E., Esteban, I., Ferrario, P., et al. (2020). Coherent elastic neutrino-nucleus scattering at the European Spallation Source. J. High Energy Phys., 02(2), 123–38pp.
Abstract: The European Spallation Source (ESS), presently well on its way to completion, will soon provide the most intense neutron beams for multi-disciplinary science. Fortuitously, it will also generate the largest pulsed neutrino flux suitable for the detection of Coherent Elastic Neutrino-Nucleus Scattering (CE nu NS), a process recently measured for the first time at ORNL's Spallation Neutron Source. We describe innovative detector technologies maximally able to profit from the order-of-magnitude increase in neutrino flux provided by the ESS, along with their sensitivity to a rich particle physics phenomenology accessible through high-statistics, precision CE nu NS measurements.
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SuperNEMO Collaboration(Argyriades, J. et al), Carcel, S., Diaz, J., Monrabal, F., Serra, L., & Yahlali, N. (2010). Results of the BiPo-1 prototype for radiopurity measurements for the SuperNEMO double beta decay source foils. Nucl. Instrum. Methods Phys. Res. A, 622(1), 120–128.
Abstract: The development of BiPo detectors is dedicated to the measurement of extremely high radiopurity in (TI)-T-208 and Bi-214 for the SuperNEMO double beta decay source foils. A modular prototype, called BiPo-1, with 0.8 m(2) of sensitive surface area, has been running in the Modane Underground Laboratory since February, 2008. The goal of BiPo-1 is to measure the different components of the background and in particular the surface radiopurity of the plastic scintillators that make up the detector. The first phase of data collection has been dedicated to the measurement of the radiopurity in (TI)-T-208. After more than one year of background measurement, a surface activity of the scintillators of A((TI)-T-208) = 1.5 μBq/m(2) is reported here. Given this level of background, a larger BiPo detector having 12 m(2) of active surface area, is able to qualify the radiopurity of the SuperNEMO selenium double beta decay foils with the required sensitivity of A((TI)-T-208) <2 μBq/kg (90% CL.) with a six month measurement.
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