Letter of Intent to Build a MiniBooNE Near Detector: BooNE

Abstract

There is accumulating evidence for a difference between neutrino and antineutrino oscillations at the {approx}1 eV{sup 2} scale. The MiniBooNE experiment observes an unexplained excess of electron-like events at low energies in neutrino mode, which may be due, for example, to either a neutral current radiative interaction, sterile neutrino decay, or to neutrino oscillations involving sterile neutrinos and which may be related to the LSND signal. No excess of electron-like events (-0.5 {+-} 7.8 {+-} 8.7), however, is observed so far at low energies in antineutrino mode. Furthermore, global 3+1 and 3+2 sterile neutrino fits to the world neutrino and antineutrino data suggest a difference between neutrinos and antineutrinos with significant (sin{sup 2} 2{theta}{sub {mu}{mu}} {approx} 35%) {bar {nu}}{sub {mu}} disappearance. In order to test whether the low-energy excess is due to neutrino oscillations and whether there is a difference between {nu}{sub {mu}} and {bar {nu}}{sub {mu}} disappearance, we propose building a second MiniBooNE detector at (or moving the existing MiniBooNE detector to) a distance of {approx}200 m from the Booster Neutrino Beam (BNB) production target. With identical detectors at different distances, most of the systematic errors will cancel when taking a ratio of events in the two detectors, asmore » the neutrino flux varies as 1/r{sup 2} to a calculable approximation. This will allow sensitive tests of oscillations for both {nu}{sub e} and {bar {nu}} appearance and {nu}{sub {mu}} and {bar {nu}}{sub {mu}} disappearance. Furthermore, a comparison between oscillations in neutrino mode and antineutrino mode will allow a sensitive search for CP and CPT violation in the lepton sector at short baseline ({Delta}m{sup 2} > 0.1 eV{sup 2}). Finally, by comparing the rates for a neutral current (NC) reaction, such as NC {pi}{sup 0} scattering or NC elastic scattering, a direct search for sterile neutrinos will be made. The initial amount of running time requested for the near detector will be a total of {approx}2E20 POT divided between neutrino mode and antineutrino mode, which will provide statistics comparable to what has already been collected in the far detector. A thorough understanding of this short-baseline physics will be of great importance to future long-baseline oscillation experiments.« less