A 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 $\sim 1$ eV${}^2$ 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 ($-0.5\pm 7.8\pm 8.7$), 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 (${\sin }^{2}2\hat{I}{¸}_{\hat{I}¼\hat{I}¼}\sim 35$) $\bar{\hat{I}}{½}_{\hat{I}}¼$ disappearance. In order to test whether the low-energy excess is due to neutrino oscillations and whether there is a difference between $\hat{I}{½}_{\hat{I}}¼$ and $\bar{\hat{I}}{½}_{\hat{I}}¼$ disappearance, we propose building a second MiniBooNE detector at (or moving the existing MiniBooNE detector to) a distance of $\sim 200$ 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, as the neutrino flux varies as $1/r^2$ to a calculable approximation. This will allow sensitive tests of oscillations for both $\hat{I}{½}_e$ and $\bar{\hat{I}}{½}_e$ appearance and $\hat{I}{½}_{\hat{I}}¼$ and $\bar{\hat{I}}{½}_{\hat{I}}¼$ 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 ($\hat{I}”m^2>0.1$ eV${}^2$).

43 pages, 40 figures