New Limits on Coherent Neutrino Nucleus Elastic Scattering Cross Section at the Kuo-Sheng Reactor Neutrino Laboratory

TL;DR

This study sets new experimental limits on the coherent neutrino-nucleus elastic scattering cross section using a germanium detector at the Kuo-Sheng Reactor Neutrino Laboratory, advancing the search for this elusive interaction.

Contribution

It provides the first experimental limits on the neutrino-nucleus elastic scattering cross section with reactor neutrinos using a germanium detector.

Findings

Limits at 90% CL: { ho}<4.7 for k=0.162

Limits at 90% CL: k<0.285 for { ho}=1

Analysis of 242-357 kg-days of data at 200 eVee threshold

Abstract

Neutrino nucleus elastic scattering ({\nu}Ael) with reactor neutrinos is an interaction under full quantum-mechanical coherence. It has not yet been experimentally observed. We present new results on the studies of {\nu}Ael cross section with an electro-cooled p-type point-contact germanium detector at the Kuo-Sheng Reactor Neutrino laboratory. A total of (242)357 kg-days of Reactor ON(OFF) data at a detector threshold of 200 eVee in electron equivalent unit are analyzed. The Lindhard model parametrized by a single variable k which characterizes the quenching function was used. Limits at 90% confidence level are derived on the ratio {\rho} relative to standard model (SM) cross section of {\rho}<4.7 at the predicted value of k=0.162, while k<0.285 at the SM-value of {\rho}=1. Prospects on future positive measurements are discussed.