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Measuring the Last Undetermined Neutrino Mixing Angle 13 Searching for Subdominant Oscillations in e ,. Reactor Neutrino Measurement of 13. 13 is key parameter for oscillation phenomenology since 12 and 23 are both large
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Measuring the Last Undetermined Neutrino Mixing Angle 13 Searching for Subdominant Oscillations in e , Reactor Neutrino Measurement of 13 NSD, May 1, 2003
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 and CP Violation Neutrino Mixing Matrix solar present 0 experiments future reactor and accelerator future atmospheric present NSD, May 1, 2003
Detector 2 Detector 1 Reactor Neutrino Measurement of 13 Searching for Subdominant Oscillations in e , to measure the last yet undetermined neutrino mixing angle, 13 13 oscillation signature NSD, May 1, 2003
m213 dependence True value of m231 (eV2) sin2213 sensitivity limit Sensitivity and Complementarity of 13Experiments Reactor 13experiment No matter effect Correlations are small, no degeneracies Independent of solar osc. parameters 12,m212 Sensitivity to sin2213 Ref: Huber et al., hep-ph/0303232 10-3 10-2 10-1 13sensitivity of reactor experiments comparable to JHF-SK NSD, May 1, 2003
A 13Reactor Experiment in the US ? 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) Movable detectors? Does a site like this exist? NSD, May 1, 2003
Diablo Canyon - An Ideal Site? NSD, May 1, 2003
Diablo Canyon Site 1500 ft 600 ft • Powerful: Two reactors (3.1+3.1 GW Eth) 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. NSD, May 1, 2003
An Ideal Oscillation Experiment with Variable Baseline?Possible layout of 2 or 3 detectors at Diablo Canyon FAR II: distance 2-2.5 km FAR I: distance 1.5-2 km tunnels NEAR: distance~ 0.5 km ~ 600-800 mwe ~ 400 mwe Tunnel excavation required further studies necessary NSD, May 1, 2003
Schematic ofMovable Detector • Modular, movable liquid scintillator detector to control systematics • active muon veto • Vfiducial ~ 80-100 t NSD, May 1, 2003
Summary: Reactor Measurement of 13 • Measurement of fundamental neutrino mixing angle with discovery opportunityandlong-term impact. • Reactor experiment gives clean measurement of sin2213. • Sensitivity of sin2213 < 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/ NSD, May 1, 2003