Neutrino Physics with PTOLEMY: From the mass measurement to the CNB detection

Pofi, Francesca Maria

doi:10.5281/zenodo.17801820

Neutrino Physics with PTOLEMY: From the mass measurement to the CNB detection

Pofi, Francesca Maria

Publisher: Zenodo
DOI: 10.5281/zenodo.17801820
Repository: zenodo.org
Language: en

Abstract

Parallel talk presented at the XXI International Workshop on Neutrino Telescopes - Padova 29 September - 3 October 2025 (https://agenda.infn.it/event/44606/) On behalf of the PTOLEMY Collaboration Abstract:The cosmic neutrino background is a form of radiation emitted one second after the Big Bang. It is the most abundant source of neutrinos in the Universe; however, due to its extremely low energy, it has never been directly detected. PTOLEMY aims at exploring new experimental techniques to detect the cosmic neutrino background by exploiting neutrino capture on a tritium target. This goal imposes several technological challenges, both in materials science — for the development of a solid tritium target — and in the detection of radio frequencies combined with an innovative electromagnetic spectrometer. Another critical challenge is the measurement of electron energy with extremely high resolution (50 meV), a fundamental requirement that could be achieved by employing micro calorimeters e.g. TES or electrostatic analyzers. Both tecnologies will be tested in the framework of the electron detection system.PTOLEMY is now entering the construction phase of its demonstrator, which will allow the detector proof of principle, laying the groundwork for the first experimental’s physics goal: the measurement of the neutrino mass. The current status and future developments of the project will be presented.

Full text

GRAN SASSO SCIENCE INSTITUTE Presentation for XXI Workshop on Neutrino Telescopes, October 2025! Francesca Maria Pofi on the behalf of the PTOLEMY collaboration Neutrino Physics with PTOLEMY: From the mass measurement to the CNB detection Francesca M. Pofi A Sea of ‘Still’ Neutrinos 2 Cosmic Neutrino Background (CNB) Identikit: ❖Decoupling 1 sec after Big Bang! ❖Density n 300/cm3! ❖Temperature T 1.95 K ν ≃ ν ≃ ❖Most abundant neutrinos’ source! ❖Extremely low energy E 10-4 eV! ➡Challenging detection: non-threshold " reaction needed ν ≃ Francesca M. Pofi 3 Two Measurements with One Observable Let’s take a -unstable nucleus eg Tritium (3H) What can we obtain for free? β Neutrino Mass Measurement from endpoint distortion (1° goal) First Relic Neutrinos Detection (Final goal) A.G. Cocco, G. Mangano, M. Messina, JCAP 06 (2007) 015 IDEAL ATOMIC T CASE Francesca M. Pofi PTOLEMY Ingredients 4 Extremely accurate measurement of electron energy " - (50 meV) resolution! Electron filtering! Electron slowdown! Large target mass (very low cross section for ν capture) 𝒪 100 eV CNB Ee Francesca M. Pofi A Multi-Disciplinary Detector 5 or HEA spec Francesca M. Pofi Compact Atomic Tritium 6 Minimize electrons - target interactions electron energy conserved! Compact possibility to store huge quantities! Stable no tritium released into environment ! Atomic tritium chemically bound! on graphene sheets ~ 100% H loading reached *" (1 H for each C)! High stability in vacuum! β REQUIREMENTS: SOLUTION: * M.G. Betti et al., Nano Letters 22 (2022) 2971 A. Apponi et al., arXiv:2504.11853 Francesca M. Pofi Trigger with Non-Destructive Energy Measurement 7 Aim: filter trigger determine if electron energy is near to 3H decay endpoint! Fast: (100 μs)! Raw measurement: (10 eV) resolution! Non-destructive: initial electron energy not modified! How? Cyclotron radiation spectroscopy! uniform B field cyclotron motion RF radiation emission! ➢power ➢frequency β 𝒪 𝒪 P(γ,θ) = 1 4πϵ0 2 3 |q|4B2 m2c(γ2−1)sin2θ fc=1 2π |q|B m 1 K/m+ 1 Electron kinetic energy B Pitch angle Francesca M. Pofi Exploiting Frequency Modulation 8 base: uniform magnetic field (1 T) main frequency (carrier)! extra: ➢ bouncing electrodes (longer signal) side bands @ distance" ➢ uniform electric field (drift) fc Δf= 1/Tbounc ✚ = 1.4 1.2 1 0.8 0.6 0.4 0.2 0 25.85 25.9 25.95 26 26.05 26.1 26.15 26.2 f(GHz) P(fW) ✚ ◯ Tbounc L reconstruction from K// θ Expected signal: 27 GHz, = (1 fW) fc≃ P 𝒪 carrier sideband sideband secondary Francesca M. Pofi Filter within One Meter 9 E Field → E x B drift → motion along filter" → potential hill! ➢ exponential decay @ same rate→ lateral drift balancing B Field → B x B drift → motion against increasing potential ∇ ✚ FINAL RISULT: Electrons’ slowdown + filtering" ➢ with controlled trajectory" ➢ in short space (~1 m) RF TRANSVERSE FILTER front view top view L Z! X Y! X L Francesca M. Pofi Real Spectra considering Condensed Matter Effects 16 *A. Casale et al., arXiv:2504.13259 Francesca M. Pofi Demonstrator Look 17 Francesca M. Pofi Superconductive Magnet 18 Francesca M. Pofi RF Detection Chain 19 © Nicola Rossi