Experimental neutrino physics in a nuclear landscape

Abstract

There are profound connections between neutrino physics and nuclear experiments. Exceptionally precise measurements of single and double beta-decay spectra illuminate the scale and nature of neutrino mass and may finally answer the question of whether neutrinos are their own anti-matter counterparts. Neutrino-nucleus scattering underpins oscillation experiments and probes nuclear structure, neutrinos offer a rare vantage point into collapsing stars and nuclear fission reactors and techniques pioneered in neutrino nuclear physics experiments are advancing quantum sensing technologies. In this article, we review current and planned efforts at the intersection of neutrino and nuclear experiments. This article is part of the theme issue 'The liminal position of Nuclear Physics: from hadrons to neutron stars'.

Keywords: low radioactive background experimental techniques; neutrino mass; neutrino mass ordering; neutrinos; underground science.

Figure 1.

(a) Measured integral ³H $\beta$ spectrum near the endpoint from the KATRIN experiment [13]. (b) The differential electron-capture calorimetric spectrum of ¹⁶³Ho from the ECHo experiment [14].

Figure 2.

The effective Majorana-mass observable $m_{\beta \beta }$ in neutrinoless double-beta decay searches versus the direct kinematic observable $m_{\beta }$ . The neutrino mixing parameters $U_{\alpha i}$ are varied within their ranges from oscillation experiments. The blue area is for the normal mass ordering, while the red area is for the inverted mass ordering. The next generation of $0\nu \beta \beta$ experiments aims to probe the entire inverted mass ordering through $m_{\beta \beta }$ . Adapted from [40].

Figure 3.

Relevant experimental parameters—background index, detector resolution ( $\sigma$ ) and isotopic moles—for recently completed (⊖), currently running ( $†$ ) and proposed ( $‡$ ) $0\nu \beta \beta$ -decay search experiments. Furthermore, isotopes with high $Q_{\beta \beta }$ value offer an additional advantage since the phase-space factor $G^{0\nu }(Z,Q)$ is proportional to $Q_{\beta \beta }^5$ and radioactive backgrounds tend to be smaller at higher energy.

Figure 4.

Achieved (solid) and projected (dotted) exclusion curves for sterile neutrinos from $\beta$ -decay experiments, along with the parameter space preferred by the gallium anomaly ( $2\sigma$ contours). Adapted from [161].