Antineutrino sensitivity at THEIA

Abstract

We present the sensitivity of the Theia experiment to low-energy geo- and reactor antineutrinos. For this study, we consider one of the possible proposed designs, a 17.8-ktonne fiducial volume Theia-25 detector filled with water-based liquid scintillator placed at Sanford Underground Research Facility (SURF). We demonstrate Theia's sensitivity to measure the geo- and reactor antineutrinos via Inverse-Beta Decay interactions after one year of data taking with $11.9\times 10^{32}$ free target protons. The expected number of detected geo- and reactor antineutrinos is $218{}_{-20}^{+28}$ and $170{}_{-20}^{+24}$, respectively. The precision of the fitting procedure has been evaluated to be 6.72% and 8.55% for geo- and reactor antineutrinos, respectively. We also demonstrate the sensitivity towards fitting individual Th and U contributions, with best fit values of $N_{\text{Th}}=39{}_{-15}^{+18}$ and $N_{\text{U}}=180{}_{-22}^{+26}$. We obtain $(\text{Th}/\text{U})=4.3\pm 2.6$ after one year of data taking, and within ten years, the relative precision of the (Th/U) mass ratio will be reduced to 15%. Finally, from the fit results of individual Th and U contributions, we evaluate the mantle signal to be $S_{\text{mantle}}=9.0\pm [4.2,4.5]$NIU. This was obtained assuming a full-range positive correlation (${\rho }_c\in [0,1]$) between Th and U, and the projected uncertainties on the crust contributions of 8.3% (Th) and 7.0% (U). When considering systematic uncertainties on the signal and background shape and fluxes, the mantle signal becomes $S_{\text{mantle}}=9.3\pm [5.2,5.4]$NIU.

15 pages, 10 figures, submitted to European Physical Journal C

References in corpus (6)

• Geo-neutrinos and Earth's interior
• Radiogenic and Muon-Induced Backgrounds in the LUX Dark Matter Detector
• Reference worldwide model for antineutrinos from reactors
• Combined analysis of KamLAND and Borexino neutrino signals from Th and U decays in the Earth's interior
• Experimental Aspects of Geoneutrino Detection: Status and Perspectives
• Examining the Geometrical Model with Inverted Mass Hierarchy for Neutrinos

Cited by in corpus (4)

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• Characterization of the scintillation response of water-based liquid scintillator to alpha particles, and implications for particle identification
• Remote Reactor Ranging via Antineutrino Oscillations