Detecting supernova neutrinos with iron and lead detectors

TL;DR

This study evaluates supernova neutrino detection via neutron emission in lead and iron detectors, revealing lower neutron yields than previous estimates and highlighting the complementary roles of the two materials in understanding neutrino flavor composition.

Contribution

It provides realistic estimates of neutron yields from supernova neutrinos in lead and iron detectors based on recent simulations, emphasizing their combined potential for neutrino flavor analysis.

Findings

Neutron yields are lower than previous estimates based on earlier simulations.

Iron detectors produce fewer neutrons than lead but offer flavor-blind detection.

Combined use of lead and iron detectors can help determine neutrino flavor composition.

Abstract

Supernova (SN) neutrinos can excite the nuclei of various detector materials beyond their neutron emission thresholds through charged current (CC) and neutral current (NC) interactions. The emitted neutrons, if detected, can be a signal for the supernova event. Here we present the results of our study of SN neutrino detection through the neutron channel in lead ($^{208} {\rm Pb}$) and iron ($^{56} {\rm Fe}$) detectors for realistic neutrino fluxes and energies given by the recent Basel/Darmstadt simulations for a 18 solar mass progenitor SN at a distance of 10 kpc. We find that, in general, the number of neutrons emitted per kTon of detector material for the neutrino luminosities and average energies of the different neutrino species as given by the Basel/Darmstadt simulations are significantly lower than those estimated in previous studies based on the results of earlier SN simulations. At the same time, we highlight the fact that, although the total number of neutrons produced per kTon in a iron detector is more than an order of magnitude lower than that for lead, the dominance of the flavor blind NC events in the case of iron, as opposed to dominance of $\nu_e$ induced CC events in the case of lead, offers a complementarity between the two detector materials so that simultaneous detection of SN neutrinos in a lead and a sufficiently large iron detector suitably instrumented for neutron detection may allow estimating the fraction of the total $\mu$ and $\tau$ flavored neutrinos in the SN neutrino flux and thereby probing the emission mechanism as well as flavor oscillation scenarios of the SN neutrinos.