Development of photon and phonon cryogenic detectors coupled to scintillating crystals

• Applicant: Privatdozentin Dr. Loredana Gastaldo
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 501391207

Double beta decay in which two electrons and two electron antineutrinos are simultaneously emitted by a nucleus is a process foreseen by the Standard Model of Particle Physics and becomes the leading process when single beta decay is forbidden due to energy conservation or large change of angular momentum. Thinking beyond the Standard Model of Particle Physics and allowing for violation of total lepton number, a double beta decay without the emission of the two electron anti-neutrinos could exist. This so-called neutrinoless double beta decay implies that neutrinos are massive Majorana particles. While double beta decay with the emission of two electron anti-neutrinos has been observed for several nuclides, showing halflife of the order of 10^19 – 10^21 years, neutrinoless double beta decay has still not been experimentally demonstrated. The existence of such a process would define a direction for understanding the fundamental properties of neutrinos and, with that, also how to extend the present Standard Model of Particle Physics. This attractive perspective has motivated many collaborations to build very challenging experiments for the search of this very rare process, reaching the possibility to test halflife of the order of 10^26 years and already planning for the next generation experiments where halflife of the order of 10^28 years could be tested. This proposal has as objective the development of high energy resolution integrated photon and phonon detectors, named P2, based on low temperature metallic magnetic calorimeters to be coupled to scintillating crystals containing Mo-100, a nuclide undergoing double beta decay. We aim to demonstrate that the proposed detector design can achieve superior performance with respect to the already used photon and phonon detectors, in terms of energy and time resolution. Improving these two key parameters will lead to an important reduction of background by reducing the region of interest where to look for neutrinoless double beta decay event (improved energy resolution), and by reducing the contribution of the Mo-100 pile-up events to the background (improved time resolution). In addition, we propose to investigate the use of a phonon detector composed by three independent metallic magnetic calorimeter channels for the identification of the event position based on pulse shape analysis. The possibility to define a fiducial volume will be of utmost importance to remove the contribition to the background due to surface events. The proposed development is part of the detector optimization for the AMoRE experiment searching for neutrinoless double betal decay in Mo-100. In addition, such detectors could potentially play a key role in experiments for the observation of direct dark matter interactions as well as for measurements of coherent elastic neutrino nucleus scattering.

• DFG Programme: Research Grants
• International Connection: South Korea
• Cooperation Partner: Professor Yong-Hamb Kim