Neutrino oscillation physics with a FNAL Proton Driver NuFact 05, Frascati, Italy June 23, 2005 Walter Winter Institute for Advanced Study, Princeton Editors: Steve Brice, Debbie Harris (FNAL), Walter Winter (IAS)

NuFact 05 - FNAL PD - W. Winter Contents Introduction Performance indicators Proton Driver (PD) physics scenarios Some examples for PD experiments PD and evolution of the global program Summary June 23, 2005 NuFact 05 - FNAL PD - W. Winter

What is a Proton Driver? (a “theorist’s perspective”) A terribly complicated machine to obtain more protons Machine part of the FNAL proton driver: LINAC + Main injector modifications (Giorgio Apollinari’s talk) Goal: 8 GeV and (up to) 120 GeV protons at 2 MW = Factor 5-10 past current FNAL proton source at 120 GeV Cost: 300-500M$ Proton Driver = Higher Luminosities June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Why do we need a Proton Driver? Example: sin22q13 sensitivity limit at NOvA: Appearance rate prop. to sin22q13 (1st approximation) Sensitivity limit E. g. Factor two better limit = factor four in luminosity Thus: Much higher luminosities required to go further! 5 x Flux = Proton Driver 5 x Running time = 25 years (unrealistic) 5 x Detector mass = 150kt (150M$ x 5 = even more exp.) L = Flux x Detector mass x Running time “Recyclable” for other exps Probably not re-usable June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Fermilab PD study: Facts Two parts: How to built a more powerful proton source (W.Foster) What to do with the protons (S. Geer) “The Fermilab Director has requested a study […], which will require documentation sufficient to establish mission need as defined by the DOE CD-0 process.” Study launched at PD Workshop at Fermilab in Oct. 2004 Director’s review in March 2005 Missing working group reports + CD0 documentation will probably be publically available soon … June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Fermilab PD study - Structure PD study (Physics part) CD0 documentation for DOE S. Geer Neutrino oscillations S. Brice, D. Harris, W. Winter THIS TALK! Authors (preliminary): Antusch, Bazarko, Cooper, DeJongh, Diwan, Feldman, Finley, Geer, Huber, deGouvea, Jansson, Kersten, Lindner, Mena, Michael, Parke, Ratz, Rolinec, Schwetz, Stefanski, Van de Water Neutrino scattering J. Morfin, R. Ransome, R. Tayloe Fundamental neutrino properties (X-section measurem. for osc. Experiments, neutrino-electron scattering) Fundamental properties of matter Broader physics program T. Bowles, H. Cheung, D. Christian, G. Greene, P. Kasper, M. Mandelkern, P. Ratoff, R. Ray, R. Roberts, H. Nguyen, T. Yamanaka Muon physics (EDM, muon g-2, rare decays); Kaon, Pion, Neutron, and Antiproton experiments June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Potential users of the FNAL PD NOvA MiniBOONE Super-NOvA (2nd detector) Others? Proton Driver (machine) New beamline BB superbeam FNAL- DUSEL “multi-GeV” Neutrino factory “some GeV” New beamline “use all protons” BB + n x NBB b-Beam 120 GeV 8 GeV June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Why is the neutrino oscillation part so challenging? Many potential experiments using the proton driver Which of these experiments should one build Depends on physics case! Key questions: Does one need the FNAL proton driver in any physics case? What does one do with it then? Should be answered by neutrino oscillation study PD Study has a quite “strategical” character June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Pre-Proton Driver program PD Timescale: Starts operation ~ 2014? Ten more years to go until then What happens until then (physics-wise)? Pre-Proton Driver: ~ 2005 – 2014 US program: European/Japanese program: MiniBOONE KEK MINOS CNGS NOvA T2K … … (Chapter 3, Neutrino Oscillation Document = NOD) June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Proton Driver Physics cases Main scenarios Deal with following questions: q13 discovered or not? How large is q13? How measure the mass hierarchy and CP violation? Special cases LSND confirmed q23 still consistent with maximal mixing Something unexpected happens (For details, see working group report) (Chapters 4-6, NOD) (Chapter 7, NOD) June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Predictions for future experiments (or: How to simulate PD-based experiments) Existing experiments: Future experiments: ? But: only one set realized by nature! Simulated data Fit parameters to data: Precision of quantity of interest Input parameters Data Fit parameters to data: Precision of quantity of interest Simulation of future experiments = “Hypothesis testing” June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Simulated versus fit parameters Simulated/true params Represent the values implemented by nature Known within current limits Change the event rates, top. Have to be interpreted like “If the value of … is …, then the performance will be …” - Luck or not luck? Used for risk minimization! Determine the precision of the quantity of interest “Unused” parameteres are usually marginalized over (projection onto axis/plane of interest) Source of correlations! June 23, 2005 NuFact 05 - FNAL PD - W. Winter

q13 performance indicators q13 exclusion limit (sensitivity limit): Describes the new q13 limit for the hyopthesis of no signal (q13=0) Correspond to new limit after the experiment has been (unsuccessfully) performed Define as largest fit value of q13=0, which fits true q13=0 Straightfoward inclusion of correlations and degeneracies Does not depend on the simulated dCP and mass hierarchy! q13 discovery reach: Describes if q13=0 can be excluded for the hyopthesis of a certain set of parameters (q13>0) Almost no correlations+degeneracies (since fit q13=0) Depends on simulated q13, mass hierarchy, and dCP June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Discovery plots and “Fraction of dCP” Read: For sin22q13=0.04, we expect a discovery for 20% of all values of dCP Sensitive region as function of true q13 and dCP New primer in PD-NOD! dCP values now stacked for each q13 Fraction of dCP for successful discovery June 23, 2005 NuFact 05 - FNAL PD - W. Winter

“Fraction of dCP” = Measure for luck? Remember: Only one set of simulated values actually realized by nature! For uniform distribution in dCP: Fraction of dCP = Probability to discover dCP dCP comes from a complex phase factor eid in the mixing matrix Thus: Distribution in sin d theoretically “unnatural”!? No “luck” needed; works for all d, hier. “Typical” d; 50-50 chance Best case d, hierarchy June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Main PD scenarios … ... from q13 exclusion limit at PD startup Need substantially more than existing beamline + detector But: superbeams way to go Conceptual cases in PD study Probably need neutrino factory Could work on CP violation+ mass hierarchy with existing beamline + det. NUE=“NuMI Up- graded Experiment” ~ NOvA Scenario 3: Discovery unlikely until PD startup Scenario 1: Certainly discovered until PD startup Scenario 2: Discovery likely before PD startup June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Scenario 1: sin22q13 larger than ~0.04 CP fraction “1” not possible! NUE ~ NOvA T2K*: T2K+Japenese PD T2HK: T2K+Japanese PD+ Hyper-K-Detector Excellent results with FNAL-PD + possibly existing equipment (NOvA) Synergy with Japanese program (especially for mass hierarchy) If Japanese program not funded: Other options (next slides) June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Scenario 2: 0.01 < sin22q13 < 0.04 NUE ~ NOvA 2nd NUE ~ Super-NOvA Second NUMI off-axis detector promising alternative New long baseline experiment could “do it all” What specific option preferred needs further study … June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Example 1: BB FNAL-Homestake Two-Peak Structure still visible at 1290km FNAL-Homestake very competitive for q13 and also dCP See hep-ex/0407047 for more details 2540km 1290km Figures from M.Diwan June 23, 2005 NuFact 05 - FNAL PD - W. Winter

NuFact 05 - FNAL PD - W. Winter Example 2: 2 MW + 2 MW beam ~8m 30 mR maximum off axis D.Michael, C.White, M.Messier 1290km Uses all the protons from Booster Main Injector ~200M 150kT Liquid Argon ~4m Consider LAr and H2OC 90% CL 99% CL 8 GeV protons 120 GeV protons June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Scenario 3: sin22q13 smaller than ~0.01 NuFact: 50kt magn. Iron det. 4+4 year running 4 MW target power (~1021 useful muon decays/year) 50 GeV neutrinos For large sin22q13>0.003: New long baseline experiment interesting alternative For smaller values: Neutrino factory (or b-Beam) can do measurements in large fraction of parameter space (see P. Huber’s talk) June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Example: b-Beam at Fermilab? “Stretched Tevatron“ aimed at Soudan Total circumference: approximately 2 x Tevatron 320m elevation @ 58 mrad A. Jansson (Huber, Lindner, Rolinec, WW, to appear) June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Evolution of q13 discovery limit Characterize dependence on dCP as bands reflecting all possible chases Choose starting times + luminosities as close as possible to values in respective LOIs/proposals All exps: five years running New generation will quickly determine potential Reactor experiments provide complementary information! For inverted hierarchy: Beam limits shift somewhat down! (from: FNAL proton driver study, to appear) June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Examples for q13 cases (1) Assume: Actual value of sin22q13 = 0.03 ~2012-2013: q13 signal likely at superbeams or reactor experiments PD+NUE+2nd NUE very competitive Fast+cost efficient alternative to T2HK!? June 23, 2005 NuFact 05 - FNAL PD - W. Winter

Examples for q13 cases (2) Assume: Actual value of sin22q13 = 0.007 Discovery of q13 unlikely without PD and impossible for T2K If no PD at Fermilab, probably no further superbeam program! But: One could have done almost of all the physics with a superbeam program! June 23, 2005 NuFact 05 - FNAL PD - W. Winter

NuFact 05 - FNAL PD - W. Winter Summary We need the FNAL proton driver in all physics cases (but not all possible discussed experiments!) The FNAL Proton Driver is the next logical step in the FNAL neutrino oscillation program beyond NOvA The FNAL-based neutrino oscillation program is unique, because There are already existing experiments. Thus: No complete program from scratch NUMI beamline is so far the only beamline with large enough matter effects to potentially resolve the mass hierarchy Synergy with reactor program + Japanese program For more: see http://protondriver.fnal.gov/ June 23, 2005 NuFact 05 - FNAL PD - W. Winter