1. Stokstad, Heeger NSD, May 1, 2003 Reactor Neutrino Measurement of  13 Measuring the Last Undetermined Neutrino Mixing Angle  13 Searching for Subdominant Oscillations in e  , 

2. Stokstad, Heeger NSD, May 1, 2003  13 and CP Violation ? Neutrino Mixing Matrix  13 is key parameter for oscillation phenomenology since  12 and  23 are both large  13 determines whether CP violation is accessible CP proportional to  13  13 is key parameter for oscillation phenomenology since  12 and  23 are both large  13 determines whether CP violation is accessible CP proportional to  13 atmospheric present solar present reactor and accelerator future 0  experiments future

3. Stokstad, Heeger NSD, May 1, 2003 Reactor Neutrino Measurement of  13 Detector 1 Detector 2 Searching for Subdominant Oscillations in e  ,  to measure the last yet undetermined neutrino mixing angle,  13  13 oscillation signature

4. Stokstad, Heeger NSD, May 1, 2003 Sensitivity and Complementarity of  13 Experiments Reactor  13 experiment No matter effect Correlations are small, no degeneracies Independent of solar osc. parameters  12,  m 21 2 sin 2 2  13 sensitivity limit  m 2 13 dependence True value of  m 2 31 (eV 2 ) Sensitivity to sin 2 2  13 10 -1 10 -3 10 -2 Ref: Huber et al., hep-ph/0303232  13 sensitivity of reactor experiments comparable to JHF-SK

5. Stokstad, Heeger NSD, May 1, 2003 Movable detectors? Does a site like this exist? Site Requirements 1. A reactor, or multiple-reactor complex 2. Sites for 2-3 detectors at distances of 1-5 km from reactor 3. Detector overburden for reduction of cosmic ray background Man-made overburden or Underground site in a mine (good overburden) Underground site in tunnels (movable detectors) A  13 Reactor Experiment in the US ?

6. Stokstad, Heeger NSD, May 1, 2003 Diablo Canyon - An Ideal Site?

7. Stokstad, Heeger NSD, May 1, 2003 Powerful: Two reactors (3.1+3.1 GW E th ) on the California coast Overburden: Horizontal tunnel could give 800 mwe shielding! Infrastructure: Roads built for heavy machinery. Controlled access. Scientific Collaborations: existing collaborations between PG&E and marine scientists, biologists, and geologists with site access. Diablo Canyon Site 1500 ft 600 ft

8. Stokstad, Heeger NSD, May 1, 2003 ~ 600-800 mwe FAR II: distance 2-2.5 km FAR I: distance 1.5-2 km NEAR: distance~ 0.5 km Tunnel excavation required  further studies necessary An Ideal Oscillation Experiment with Variable Baseline? Possible layout of 2 or 3 detectors at Diablo Canyon tunnels ~ 400 mwe

9. Stokstad, Heeger NSD, May 1, 2003 Schematic of Movable Detector Modular, movable liquid scintillator detector to control systematics active muon veto V fiducial ~ 80-100 t

10. Stokstad, Heeger NSD, May 1, 2003 Summary: Reactor Measurement of  13 Measurement of fundamental neutrino mixing angle with discovery opportunity and long-term impact. Reactor experiment gives clean measurement of sin 2 2  13. Sensitivity of sin 2 2  13 < 0.005 comparable to next-generation accelerator experiments. A timely  13 measurement will define the future of accelerator physics. Reactor results will be on a timescale that complements off-axis results Further design studies and site evaluation necessary. http://theta13.lbl.gov/

11. Stokstad, Heeger NSD, May 1, 2003