The Capabilities of Monochromatic EC Neutrino Beams with the SPS Upgrade

TL;DR

This paper evaluates the potential of monochromatic electron capture neutrino beams from CERN's SPS upgrade for precision measurements of neutrino oscillations, especially CP violation, highlighting the importance of higher energies and longer baselines.

Contribution

It analyzes the capabilities of monochromatic neutrino beams with SPS upgrade energies, demonstrating improved sensitivity to CP violation with specific configurations.

Findings

Higher SPS energies enhance CP violation sensitivity.

Longer baselines improve measurement precision.

Upgraded SPS with higher gamma factors offers better physics potential.

Abstract

The goal for future neutrino facilities is the determination of the U(e3) mixing and CP violation in neutrino oscillations. This will require precision experiments with a very intense neutrino source and energy control. With this objective in mind, the creation of monochromatic neutrino beams from the electron capture decay of boosted ions by the SPS of CERN has been proposed. We discuss the capabilities of such a facility as a function of the energy of the boost and the baseline for the detector. We conclude that the SPS upgrade to 1000 GeV is crucial to reach a better sensitivity to CP violation iff it is accompanied by a longer baseline. We compare the physics potential for two different configurations: I) $\gamma=90$ and $\gamma=195$ (maximum achievable at present SPS) to Frejus; II) $\gamma=195$ and $\gamma=440$ (maximum achievable at upgraded SPS) to Canfranc. The main conclusion is that, whereas the gain in the determination of U(e3) is rather modest, setup II provides much better sensitivity to CP violation.