Gadolinium in water Cherenkov detectors improves detection of supernova $\nu_e$

Understand

Detecting supernova $\nu_e$ is essential for testing supernova and neutrino physics, but the yields are small and the backgrounds from other channels large, e.g., $\sim 10^2$ and $\sim 10^4$ events, respectively, in Super-Kamiokande.

• We develop a new way to isolate supernova $\nu_e$, using gadolinium-loaded water Cherenkov detectors.
• The forward-peaked nature of $\nu_e + e^- \rightarrow \nu_e + e^-$ allows an angular cut that contains the majority of events.
• Even in a narrow cone, near-isotropic inverse beta events, $\bar{\nu}_e + p \rightarrow e^+ + n$, are a large background.