First Constraint on the Diffuse Supernova Neutrino Background through the CE$\nu$NS process from the LZ experiment

TL;DR

This paper presents the first experimental limit on the diffuse supernova neutrino background (DSNB) using the CE$ u$NS process in the LZ xenon detector, setting new bounds on neutrino fluxes at energies above 19.3 MeV.

Contribution

It introduces the first measurement of DSNB limits via the CE$ u$NS process in a dual-phase xenon detector, expanding detection methods for neutrino backgrounds.

Findings

Set an upper limit on DSNB $ u_x$ flux at 686-826 cm$^{-2}$s$^{-1}$ for E$>$19.3 MeV.

Demonstrated the feasibility of using CE$ u$NS in xenon detectors for DSNB searches.

Achieved a limit comparable to the best existing bounds, with potential for improvement.

Abstract

We report the limits on the diffuse supernova neutrino background (DSNB) flux and the fundamental DSNB parameters measured from the first science run of the LUX-ZEPLIN (LZ) experiment, a dual-phase xenon detector located at the Sanford Underground Research Facility in Lead, South Dakota, USA. This is the first time the DSNB limit is measured through the process of the coherent elastic neutrino-nucleus scattering (CE$\nu$NS). Using an exposure of 60~live days and a fiducial mass of 5.5~t, the upper limit on the DSNB $\nu_x$ (each of $\nu_\mu$, $\nu_\tau$, $\bar\nu_\mu$, $\bar\nu_\tau$) flux is $686-826$~cm$^{-2}$s$^{-1}$ at the 90\% confidence level for neutrino energies E$>$19.3~MeV, assuming the flux for each $\nu_x$ flavor is the same. The interval accounts for the uncertainty in existing DSNB models. The present result is comparable to the existing best limit and further improvements are expected after collecting data from an estimated 1,000-day exposure in the future.