NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Reactor Neutrino Measurement of  13 Searching for Subdominant Oscillations in e  ,  Measuring the Last Undetermined Neutrino Mixing Angle  13

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Recent Discoveries in Neutrino Physics Non-accelerator experiments have changed our understanding of neutrinos Atmospheric+Solar (Super-K) Solar (SNO) Reactor (KamLAND) Neutrinos are not massless (mass is small: m e < m e ) Evidence for neutrino flavor conversion e   Combination of experimental results show that neutrinos oscillate

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 U MNSP - Neutrino Mixing Matrix atmospheric present solar present Present and Future Measurements Dirac phase Majorana phases reactor and accelerator future 0  experiments future accelerator future solar future  12 = 30.3°  23 = ~ 45° Solar Atmospheric Chooz + SK tan 2  13 < 0.03 at 90% CL maximal large small … at best No good ‘ad hoc’ model to predict  13. If  13 <  12, perhaps a symmetry? Proposal for reactor  13 experiment

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003  13 and CP Violation ? For 3 Dirac neutrinos … Next generation reactor experiments Future accelerator experiments measurement of   e and   e yields  13,  CP appearance experiment disappearance experiment but observation of oscillation signature  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

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003  13 Neutrino Oscillation Experiments Central Questions in Neutrino Oscillation Physics 1. What is the e coupling of 3 ? How large is  13 ? 2. What are  13,  m 2 31,  CP,  12,  m 2 21,  23,  m 2 32 ? 4. Is there CP ? Time  13 : an opportunity for discovery Next generation reactor experiments sin 2 2  13 sensitivity: 3  no matter effects, little parameter correlation Future accelerator experiments sin 2 2  13 sensitivity: matter effects, correlation sensitivity to   13 : breaks correlation, helps with determination of parameters  13 : defines the future of accelerator experiments & The Role of  What is the mass pattern?

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Why Are Neutrino Oscillation Measurements Important? Window on physics at high mass scales, physics of flavor, and unification: Why are neutrino masses so small? Why are the mixing angles large, maximal, and small? Is there CP violation, T violation, or CPT violation in the lepton sector? Is there a connection between the lepton and the baryon sector?

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Matter-Antimatter Asymmetry (  B≠0) from Leptogenesis Difficult to generate a baryon asymmetry  B≠0 using quark matrix CP violation Generate using CP or CPT violation in the lepton sector  B-L processes then convert a neutrino excess to baryon excess (Sign and magnitude may be able to generate the observed baryon asymmetry) Difficult to generate a baryon asymmetry  B≠0 using quark matrix CP violation Generate using CP or CPT violation in the lepton sector  B-L processes then convert a neutrino excess to baryon excess (Sign and magnitude may be able to generate the observed baryon asymmetry)

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003  13 Sensitivity of Accelerator Experiments Ref: Diwan et al., hep-ph/ Measurement of   e and   e yields  13,  CP

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 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

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 MC Studies Normalization: 10k events at 10km ‘far-far’ L 1 =6 km L 2 =7.8 km ‘near-far’ L 1 = 1 km L 2 = 3 km Oscillation Parameters: sin 2 2  13 = 0.14  m 2 = 2.5 x eV 2

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Sensitivity and Complementarity of  13 Experiments Accelerator experiments (superbeams) Sensitivity to mass hierarchy and  CP Sensitivity to  23 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  Ref: Huber et al., hep-ph/

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Sensitivity to CP Violation Long-Term Impact of a Reactor  13 Measurement Different sensitivity reductions by systematics Correlations& degeneracies lead to severe limitations in accelerator experiments Improvements by combining experiments Sensitivity to  CP =+  /2 True value of  m 2 12 (eV 2 ) Ref: Huber et al., hep-ph/ True value of sin 2 2  13 sin 2 2  13 JHF-SK JHF-HK NuFact-I NuFact-II Systematics Correlation Degeneracy sin 2 2  13

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, A reactor, or multiple-reactor complex 2. Sites for 2+ detectors at distances of ~O(km) from the reactor site 3. Detector overburden for reduction of cosmic ray background Man-made overburden or Underground site- mine - railway tunnels Tunnels: - Preferably abandoned and deep - Railroad tracks provide a convenient deployment mechanism - Other obvious benefits include being able to switch the detectors. Site Requirements for Reactor  13 Measurement Movable detectors? Does a site like this exist?

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Russian  13 Proposal at Krasnoyarsk: Kr2Det ~20000 ev/year ~1.5 x 10 6 ev/year Ref: Marteyamov et al. hep-ex/ Reactor

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Russian  13 Proposal at Krasnoyarsk: Kr2Det L near = 115 m, L far =1000 m, N far = 16000/yr Ratio of Spectra Ref: Marteyamov et al. hep-ex/

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Japanese  13 Proposal at Kashiwazaki Kashiwazaki -7 nuclear power stations - requires construction of underground shaft for detectors near far Kashiwazaki-Kariwa Nuclear Power Station

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 near far  13 Proposal at Kashiwazaki

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 A  13 Reactor Experiment in the US? Interest from several US groups Argonne National Laboratory Caltech Columbia University (Fermilab National Laboratory) …. LBNL? Several suitable candidate reactor sites in the US Several underground sites and facilities under evaluation

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Diablo Canyon Site

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Diablo Canyon Site Two reactor site ( GW E th ) near hills on the California coast Horizontal tunnel could give 600 mwe shielding No reactor off time, may need new techniques to measure background For CHOOZ, a 5 ton liquid-scintillator detector at 1 km, N = 2700 in 200 days For a 300-ton liquid scintillator detector at 4 km from Diablo Canyon reactors: N ≈12000 in 300 days

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Timescale and Size of a  13 Reactor Project moderate scale (~$30-40M ) Estimated 5 years from LOI to run Fraction of cost of accelerator experiment Reactor results will be on a timescale that complements off-axis results CP precision studies JHF-SK, NuMI off-axis Reactor  13  13 run

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 From recent reports, conferences, and committees… Lincoln Wolfenstein, March 2003 KITP Conference on Neutrinos: Data, Cosmos, and Planck Scale HEPAP Facilities Committee, March 2003 “The observation of oscillation of one type of neutrino into another and the implication that neutrinos have been major discoveries of the past few years….The measurement [of  13 ] has important scientific potential” HEPAP Facilities Committee, March 2003 “The observation of oscillation of one type of neutrino into another and the implication that neutrinos have been major discoveries of the past few years….The measurement [of  13 ] has important scientific potential” LBNL Neutrino Working Group, March 2003 “The most important experiment for determining the future direction of neutrino physics is the measurement of  13 …LBNL should pursue this option vigorously with the goal of leading a US experiment.” LBNL Neutrino Working Group, March 2003 “The most important experiment for determining the future direction of neutrino physics is the measurement of  13 …LBNL should pursue this option vigorously with the goal of leading a US experiment.”

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Conclusions: 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, with sensitivity of sin 2 2  13 < comparable to next-generation accelerator experiments. Reactor  13 experiment is a medium-size project. Suitable for Berkeley, natural continuation of current program.  A timely  13 measurement will define the future of accelerator physics. Reactor experiments cannot replace superbeams. Accelerator experiments needed for determination of mass hierarchy and  CP. Helps to resolve correlations and parameter degeneracies, important for determining the true values of sin 2 2  13 and  CP.

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Further Information:  13 Resource Site References, Proposals, LBNL Activities, Workshops, …

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Monte Carlo Studies Fits for sin 2 2  13 Fit Parameters P1 = sin 2 2  13 P2 = normalization ~ 1 P3 = near distance (fixed) P4 = far distance (fixed) P5 = mass2 Since  2 /DOF = ~1, errors are representative of 1- sensitivity of different scenarios ‘far-far’ L 1 =6 km L 2 =7.8 km ‘near-far’ L 1 = 1 km L 2 = 3 km

NWG Presentation Heeger, Freedman, Kadel, Luk LBNL, April 11, 2003 Beyond the Standard Model: Neutrino Mass & Mixing Neutrino Flavor Transformation through Oscillations If neutrinos have mass leptons can mix: Flavor eigenstates are a mixture of mass eigenstates, and evolve with time or distance Dirac phase Majorana phases For 3 neutrinos …