Detector R&D for future neutrino experiments with the NuMI beamline.

This document is the result of a request from the Fermilab directorate to (i) investigate the detector technology issues relevant for future long baseline experiments and (ii) consider the associated detector R and D that would be needed to prepare the way for future neutrino oscillation experiments using the NuMI beamline. Because of the narrow energy spread provided by an off-axis beam and the resulting low intrinsic electron neutrino background, as well as the very favorable duty cycle of the NuMI beamline, a well-placed neutrino detector at the surface of the earth could take the next important steps in neutrino oscillation physics. The biggest outstanding issue in this field is whether or not the last unmeasured element of the leptonic mixing matrix, parameterized by the mixing angle {theta}{sub 13}, is nonzero. If it is in fact non-zero, this opens the door to measurements of the neutrino mass hierarchy and, if the solar neutrino oscillations are described by the LMA solution, searches for CP violation in the lepton sector. In order to get to any of these measurements, an off-axis detector must be capable of measuring the {nu}{sub {mu}}({bar {nu}}{sub {mu}}) {yields} {nu}{sub e}({bar {nu}}{sub e}) transition probabilities as well as the {nu}{sub {mu}}({bar {nu}}{sub {mu}}) survival probabilities, at the energies present in these off-axis beams, which could lie anywhere from 0.6 to 3 GeV. Optimal baselines and energies will depend on the physics goal of the experiment. For example, an optimization of the sensitivity for {nu}{sub e} appearance from a {nu}{sub {mu}} beam assuming {Delta}m{sub 32}{sup 2} = 3 x 10{sup -3} eV{sup 2} would lead to a baseline of {approx} 700-900 km and an energy of {approx} 2.2 GeV