Super-ORCA: Measuring the leptonic CP-phase with Atmospheric Neutrinos and Beam Neutrinos

Abstract

Studying the atmospheric neutrino oscillation probabilities below 2 GeV with a multi-megaton Cherenkov detector allows for a measurement of the leptonic CP-phase ${\delta }_{CP}$. The most relevant CP-sensitive energy range is below the neutrino detection threshold of KM3NeT/ORCA, which is an underwater Cherenkov detector optimised to determine the neutrino mass ordering by measuring the oscillation pattern of 3-30 GeV atmospheric neutrinos. With Super-ORCA, a $\sim 10$ times more-densely instrumented version of ORCA, the detection threshold can be lowered and the event reconstruction capabilities improved. In this paper, the key detector performance indicators for a possible Super-ORCA detector and the sensitivity to ${\delta }_{CP}$ with atmospheric neutrinos are presented. Including systematics, a 1$\sigma$-resolution on ${\delta }_{CP}$ of about $38^{\circ }$ ($23^{\circ }$) is achieved for ${\delta }_{CP}=0$ (${\delta }_{CP}=\pi /2$) after 10 years. In addition, the potential of using a neutrino beam from the Protvino accelerator facility to the Super-ORCA detector is discussed. With this, a 1$\sigma$-resolution on ${\delta }_{CP}$ of about $10^{\circ }$ ($16^{\circ }$) is achieved for ${\delta }_{CP}=0$ (${\delta }_{CP}=\pi /2$) after 10 years.

presented at the 36th ICRC (Madison, WI; 2019)