Finding Trafficked Radiological Materials via Coherent Elastic Neutrino-Nucleus Scattering

TL;DR

The paper addresses whether CEνNS with superconducting detectors can detect trafficked radiological materials by deriving the minimum detector exposure (in ton-min) required to rule out a source at 95% CL under ideal conditions for eight trafficking cases across four isotopes. It generates isotope-specific neutrino spectra, computes CEνNS cross sections, and estimates reaction rates to map feasibility against CUORE and Colossus detectors. The key finding is that only very large-activity ^137Cs sources could be detectable under optimistic assumptions, while other isotopes are not feasible with current designs; realistic performance further degrades detectability. The work provides a quantitative framework for CEνNS-based safeguards and highlights substantial technological gaps and database dependence, suggesting future work with broader data and next-generation cryogenic detectors to improve practicality.

Abstract

The potential to use neutrinos for nuclear non-proliferation has been heavily debated due to the tension between production abundance and low interaction rate. A newly detected neutrino interaction channel, coherent elastic neutrino-nucleus scattering (CE$ν$NS), could potentially end this debate due to its improved cross-section compared to other neutrino interactions. This paper presents a feasibility study for the use of CE$ν$NS superconducting detectors to find trafficked radiological materials. To do this, we calculated the minimal activity required for situational detection under ideal conditions, without background, at 95% confidence level. This analysis was performed for four commonly smuggled radioisotopes: $^{137}$Cs, $^{109}$Cd, $^{192}$Ir, and $^{57}$Co. Using these results, we conclude that CE$ν$NS could be used to discover trafficked $^{137}$Cs sources with an activity above the PBq level, but that it is not applicable for finding other radioactive sources. This framework can also be applied to other nuclear security concerns, such as safeguarding generation IV nuclear reactors.

Figures (4)

• Figure 1: Neutrino spectra for the four isotopes under study: A) $^{137}$Cs, B) $^{109}$Cd, C) $^{192}$Ir, and D) $^{57}$Co. These spectra were generated using sins. The delta functions are $\nu_e$ from electron capture decay paths while the continuous curves are $\bar{\nu_e}$ from $\beta^-$ decay. None of the chosen isotopes decayed via $\beta^+$ decay. The different decay paths can be found in kaeri.
• Figure 2: The cross sections of Al, Zn, and Sn, assuming the theoretical minimum recoil threshold, up to 8 MeV. The sub-figure shows cross sections up to 100 keV, highlighting the different minimum-detectable neutrino masses.
• Figure 3: Minimum detector exposure for 95% confidence of source absence as a function of source activity for the following sources: A) $^{137}$Cs, B) $^{109}$Cd, C) $^{192}$Ir, and D) $^{57}$Co. These results were generated using Eq \ref{['eq:important']}. Grey dashed lines correspond to cases from the CNS and NIS databases which are detailed in Table \ref{['tab:isotopes']}.
• Figure 4: Minimum detector exposure for 95% confidence of $^{137}$Cs source absence as a function of activity, based on current experimental detection parameters.