Conclusion

7 Conclusion

The possibility of making a low cost, very intense high energy proton source at the Brookhaven Alternating Gradient Synchrotron (AGS) along with the forthcoming new large underground detectors at either the National Underground Science and Engineering Laboratory (NUSEL) in Homestake, South Dakota or at the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico, allows us to propose a program of experiments that will address fundamental aspects of neutrino oscillations and CP-invariance violation. This program of experiments is unique because of the very long baseline of more than 2500 km from Brookhaven National Laboratory to the underground laboratories in the West, the high intensity of the proposed conventional neutrino beam, and the possibility of constructing a very large array of water Cherenkov detectors with total mass approaching 1 megaton. This report examined the design and construction of the necessary AGS upgrades and the new neutrino beam which will have a proton beam of power ∼1.0 MW. We have examined the potential physics reach of such an experiment. We used the running scenario of a 1 MW AGS, 500 kT of fiducial detector mass, and 5× 10⁷ secs of running time. With these conditions, we conclude that such an experiment is capable of precisely measuring Δ m₃₂² and sin² 2 θ₂₃; it has excellent sensitivity to sin² 2 θ₁₃ with a signal spectrum that is very distinctive. Moreover, if sin² 2 θ₁₃ is sufficiently large (> 0.01) the experiment is sensitive to the CP-violation parameter δ_CP with only neutrino running. With the additional option of running in anti-neutrino mode, the experiment will be able to distinguish between the cases Δ m₃₁² > 0 versus Δ m₃₁² < 0 using distinctive distortions to the observed electron or positron spectrum. Lastly, the very long baseline will allow the measurement of Δ m₂₁² with approximately the same resolution as KAMLAND but in the ν_µ→ ν_e appearance channel if the LMA solution is correct for the solar neutrino deficit.

The AGS complex is unique because it can be upgraded simply by increasing the repetition rate of the machine. This ability allows us the flexibility to continuously upgrade the facility to as much as 4.0 MW [35]. In this proposal we have examined upgrades up to 1.0 MW. The direct costs of such an upgrade are estimated to be approximately $140M. This compares well with the estimated costs for the detectors and the neutrino beam-line. Neither the duration of the construction period nor the anticipated cost of the improvements to the BNL AGS complex is large in relation to plans and expenditures now usual for major apparatus in high energy and elementary particle physics. Moreover, the improvements to the AGS and the new beam line will be available for carefully chosen other physics (for example, rare muon and kaon decays as well as muon EDM measurements)[51, 52], while advancing our understanding of the neutrino section.