The Very Long Baseline Neutrino Oscillations Experiment Presented to FCP05 Neutrino Session by

1. The Very Long Baseline Neutrino Oscillations Experiment Presented to FCP05 Neutrino Session by Tom Kirk Brookhaven National Laboratory Nashville, TN May 23, 2005

2. Chiaki Yanagisawa – SBU February 28, 2005 Signal/Background • ne CC for signal ; all nm,t,e NC , ne beam • for background Effect of cut on D likelihood No Dlikelihood cut (100%signal retained) Dlikelihood cut (~50%signal retained) Traditional Analysis Maximum Likelihood Method Preliminary Preliminary Background from p0 o CP+45 o CP+45 ne background Signal Erec Erec Signal 700 ev Bkgs 2005 (1878 from p 0+others) ( 127 from ne) Signal 321 ev Bkgs 169 (112 from p 0+others) ( 57 from ne)

3. Maximum Likelihood Method S/B • ne CC for signal ; all nm,t,e NC , ne beam • for backgrounds Effect of cut on likelihood o CP +45o CP-45 Preliminary Preliminary 50% 100% 100% 50% All Background Erec Erec Erec Erec 40% 40% Erec Erec Chiaki Yanagisawa – SBU February 28, 2005

4. Maximum Likelihood Method S/B • ne CC for signal ; all nm,t,e NC , ne beam • for backgrounds Effect of cut on likelihood o CP +135o CP-135 Preliminary Preliminary 100% 50% 100% 50% All Background Erec Erec Erec Erec 40% 40% Erec Erec Chiaki Yanagisawa – SBU February 28, 2005

5. Best Bets Scientific Reach of Future Neutrino Oscillations Exps. Parameter T2K T2K2 Reactor Nona Nona2 VLBNO. Dm322  4 %  4 % -  2 %  2 %  1 % sin2(2q23) 1.5 %  0.4 % - 0.4%  0.2 %  0.5 % sin2(2q13) a >0.02 >0.01 >0.01 >0.01 >0.01 >0.01 Dm212 sin(2q12) b - - - - - 12 % sign of (Dm322) c - - - possible yes yes measure dCP d- ~20 - - ~20 13 N-decay gain x1 x20 --- x8 Detector (Ktons) 50 1000 20 30 30+50 400 Beam Power (MW) 0.74 4.0 14000 0.4 2.0 1.5 Baseline (km) 295 e 295 e 1 810 e 810 e >2500 Detector Cost ($M) exists ~1000 20 165 +200 400 Beam Cost ($M) exists 500 exists 50 1000 400 Ops. Cost ($M/10 yrs) 500 700 50 500 600 150/500 f a detection of nm ne , upper limit on or determination of sin2(2q13) bdetection of nm ne appearance, even if sin2(2q13) = 0; determine q23 angle ambiguity cdetection of the matter enhancement effect over the entire dCP angle range d measure the CP-violation phase dCP in the lepton sector; Nona2 depends on T2K2 ebeam is ‘off-axis’ from 0-degree target direction; fwith/without RHIC operations Both results needed to resolve ambiguities! T. Kirk May 3, 2005

6. Comments on Neutrino Oscillations Experiments •Allparameters of neutrino oscillations can be measured in one experiment - the Very Long Baseline Neutrino Oscillation (VLBNO) at >2000 km - Use of a broadbandSuper Neutrino Beam at very long distances is the key - worries about p0 channel background have been successfully addressed - the VLBNO cost is comparable to or lower than less comprehensive methods •The massive LBNO detector empowers additional forefront physics topics - a powerful next-generationNucleon Decaysearch - supernova and relic neutrino searches are also possible - a deep underground detector is required for these searches – NSF’s DUSEL! • The CP-violation parameter dCP is the most difficult parameter to determine - matter effects interact with CP-violation effects - the CP-violation phase dCP has distinct effects over the full 360º range •Off-axis beam method requires multiple distances and detectors - all experiments will require of order 10 Snomass years of running - each proposed detector will achieve good statistics for most parameters • All measured oscillation parameters will be limited to ~1% precision by systematic errors except sin2(2q23) T. Kirk May 3, 2005