Conceptual Study of an ``Anti-Tagged'' Experiment Searching for muon-neutrino --> electron-neutrino Oscillation

TL;DR

This paper proposes a novel high-energy, short-baseline experiment with anti-tagging to significantly reduce background noise, aiming to conclusively test muon-neutrino to electron-neutrino oscillations as suggested by LSND.

Contribution

It introduces a new anti-tagging technique to suppress electron-neutrino background in neutrino oscillation experiments, enabling more sensitive searches for neutrino flavor change.

Findings

Electron-neutrino contamination reduced by over two orders of magnitude.

Expected 112 signal events over two years with minimal background.

Potential to set new upper limits on neutrino mixing parameters.

Abstract

We study the conceptual feasibility of a high energy, ``short baseline'', zero background experiment to search for muon-neutrino --> electron-neutrino oscillations and fully covering the area where the LSND experiment claims evidence. The natural electron-neutrino background of the muon-neutrino beam, from K and mu decays in the decay tunnel, is suppressed by a hadron blind detector that vetoes, by time coincidence, a possible electron-neutrino signal in the neutrino detector (anti-tagging technique). We discuss this new idea and we study a possible implementation in the old neutrino line of the PS accelerator, which at CERN offers the ideal $L/E$ ratio. In the anti-tagged muon-neutrino beam, the electron-neutrino contamination can be reduced by more than two orders of magnitude over conventional beams, down to 5*10^{-5}. In an ideal appearance experiment using a 300 t detector one would expect after two years 112 events according to the LSND result, with a background of 1.1-2.4 events. In case of a negative search, the 90% C.L. upper limit in the mixing angle would be sin^2 < 1.8*10^{-4}$ for large Delta(m^2) and Delta(m^2) <3.3*10^{-2} eV^2 for maximal mixing.