1. Overview for an European Strategy for neutrino Physics Yves Déclais CNRS/IN2P3/UCBL IPN Lyon Measuring the neutrino mixing matrix Reactor experiments NUMI off axis Combined sensitivity for JPARC, NUMI and reactors Conclusions CHIPP – Neutrino CH – June 22th - Neuchatel

2. Neutrino Oscillation : 3 neutrinos formalism θ sol θ 13, δ θ atm

3. The oscillation probability including matter effect 2-3 10 -2 Matter effect sensitive to : Sign of Δm 2 13 neutrino versus anti-neutrino Oscillation phase All effects are driven by θ 13 ! dominant « on peak » Neutrinos + Anti Nu -

4. Neutrino Mixing Matrix Study : which Road Map

5. Nuclear reactors as neutrino source Minimum energy for the primary signal is 1.022 MeV from e + e − annihilation at process threshold. Minimum energy for the primary signal is 1.022 MeV from e + e − annihilation at process threshold. Two part coincidence signal is crucial for background reduction. Two part coincidence signal is crucial for background reduction. Arbitrary Flux Cross Section Observable Spectrum The observable e spectrum is the product of the flux and the cross section. The observable e spectrum is the product of the flux and the cross section. The spectrum peaks around ~3.6 MeV. The spectrum peaks around ~3.6 MeV. Visible “positron” energy implies ν energy Visible “positron” energy implies ν energy From Bemporad, Gratta and Vogel Nuclear reactors are a very intense sources of ν e deriving from the  -decay of the neutron-rich fission fragments. Nuclear reactors are a very intense sources of ν e deriving from the  -decay of the neutron-rich fission fragments. A typical commercial reactor, with 3 GW thermal power, produces 6×10 20 e /s A typical commercial reactor, with 3 GW thermal power, produces 6×10 20 e /s E ν = E e + 0.8 MeV ( =m n  m p +m e  1.022)

6. Backgrounds in reactor neutrinos experiment There are two types of background… 1. Uncorrelated − Two random events that occur close together in space and time and mimic the parts of the coincidence. This BG rate can be estimated by measuring the singles rates. This BG rate can be estimated by measuring the singles rates. 2. Correlated − One event that mimics both parts of the coincidence signal. These may be caused fast neutrons (from cosmic  ’s) that strike a proton in the scintillator. The recoiling proton mimics the e + and the neutron captures. These may be caused fast neutrons (from cosmic  ’s) that strike a proton in the scintillator. The recoiling proton mimics the e + and the neutron captures. Or they may be cause by muon produced isotopes like 9 Li and 8 He which sometimes decay to β+n. Estimating the correlated rate is much more difficult!

7. How to improve the sensitivity Reactor exp. = Disappearance exp. compare total flux (and spectrum) with the no- oscillation hypothesis one depends on systematic uncertainties, like: absolute source strength, cross section, detection efficiency, fuel development over time... Basic idea: use 2 identical detectors to cancel uncertainties on neutrino flux and cross sections excellent monitoring of calibrations and efficiencies (including analysis cuts) to reduce the systematics on detectors large statistics to see small effects

8. Proposed sites Many Sites have been investigated as potential hosts to a reactor neutrino experiment. This is appropriate since getting the cooperation of the reactor company is the main challenge. SitePower (GW thermal ) Baseline Near/Far (m) Shielding Near/Far (mwe) Sensitivity 90% CL Krasnoyarsk, Russia 1.6115/1000600/6000.03 Kashiwazaki, Japan 24.0 300/1300150/2500.02 Double Chooz, France 8.4150/105030/3000.03 Diablo Canyon, CA 6.7400/170050/7000.01 Angra, Brazil 5.9500/135050/5000.02 Braidwood, IL 7.2200/1700450/4500.01 Daya Bay, China 11.5250/2100250/11000.01

9. Double-Chooz : site Near detector @100-200 m from the nuclear cores in discussion with EDF Far detector : using existing infrastructure from the previous experiment @ 1050 m LOI : hep-ex/0405032 detector cost 7.5 Meuros civil engineering ~5 Meuros (not studied) LOI accepted need for a proposal within 6 months 2 identical detectors  goal : σ relative  0.6%

10. Double CHOOZ : detector structure existing pit 7 m Target cylinder (f = 2.4m, h = 2.8m) filled with 0.1%Gd loaded liquid scintillator (12.7 Tons) Gamma catcher inside Acrylic Vessel, thickness : 60cm Non scintillating buffer  new ! mechanical structure to house PMTs Muons VETO of scintillating oil, thickness :60 cm Shielding : main tank, steel thickness 15cm Same concept as CHOOZ : the target mass is defined by the Gd loaded scintillator mass the efficiency is defined by neutron capture efficiency on Gd Performances (expected): S/B : 10  100 target : 5.5  12.7 m 3 analysis errors : 1.5%  0.2% But the changes would probably worsen the bkgd: large increase of passive material (including high Z) active target less protected due to the increase of the target volume

11. Double CHOOZ : Gd loaded scintillator Stability 0,1 % Gd in PXE LENS R&D  new metal β-diketone molecule (MPIK) Stable: 0.1% Gd-Acac (few months) Baseline recipe ~80% mineral oil + ~20% PXE + Fluors + wavelenght shifters In-loaded scintillators (0.1 %, 5% loading) are counting @Gran Sasso Spare stable recipes available (MPIK, INFN/LNGS) Gd-Acac molecule Completion of the R&D first half of 2004 Choice of the final scintillator Stability & Material compatibility  Aging tests (MPIK, Saclay) 3+ Gd Warning : long term stability and acrylic vessel damage

12. Double CHOOZ: close detector Dense material ~10-15 m Overburden ~50mwe Additional water buffer around the detector similar conditions to PaloVerde (46 mwe) large dead time for muon veto : 50% can a massive detector work at such a shallow depth ? PaloVerde and Bugey was segmented and used dedicated signature for neutron and positron

13. Double CHOOZ : Background and signal Ratio at the far detector no direct measurement accidental miscorrection may mimic or suppress an effect fake neutron capture signal rate underestimated The baseline is too short to see the L/E pattern

14. Reactor experiment sensitivity The location of the transition from rate to shape depends on the level of systematic error. 90%CL at Δm 2 = 3×10 -3 eV 2 From Huber, Lindner, Schwetz and Winter Statistical error only Fit uses spectral shape only Exposure (GW·ton·years) sin 2 2θ 13 Sensitivity The sensitivity may be pushed lower with large detectors sensitive to a shape deformation.

15. Double CHOOZ sensitivity 3 10 -2 To be conclusive a reactor experiment which intend to reach few 10 -2 in sin 2 2θ should be able to show an L/E effect according to the value of δm 2 ( which will be known at a high level of accuracy ) and to the disappearance rate measured

16. NUMI off-axis

17. NOVA detector : TASD 160 M$ ν e + n  p + e - + π 0

18. Goals of the NOνA experiment sensitivity to sin 2 (2θ 13 ) down to ~0.01 measurement of sin 2 (2θ 23 ) to 2% accuracy contribute to resolution of mass hierarchy via matter effect contribute to study CP violation in the neutrino sector NC background reduced by a narrow band beam (off axis) increase mass with cost/kiloton reduced by a factor 3 sampling 1/3 X 0 per plane for better electron id choose long baseline to enhance matter effects ν μ CC NC Beam ν e signal Beam unoscillated2285810594229 Beam oscillated575810593229853 After cuts3.615.419.1175 For 5years @ 4 10 20 pot/year, 50kton detector, sin 2 (2θ 13 ) = 0.1

19. Nova : tentative schedule 5 M$/year to improve proton intensity: Booster cycle 3  7-10 hz decrease losses … MINOS run ? (goal : 16. E20 pot

20. N0νA sensitivity

21. Mass Hierarchy

22. CP Violation

23. Reactor contribution to CP violation (Shaewitz) Input: sin 2 2θ 13 =0.058 δ CP = 270° sin 2 2θ 23 =1  0.06

24. The θ 23 Degeneracy Problem Atmospheric neutrino measurements are sensitive to sin 2 2θ 23 But the leading order term in ν μ →ν e oscillations is If the atmospheric oscillation is not exactly maximal (sin 2 2θ 23 <1.0) then sin 2 θ 23 has a twofold degeneracy 45º90º 2θ2θ2θ2θθθ sin 2 sin 2 2θ 23 sin 2 θ 23

25. Solving the θ 23 degeneracy with reactor (Shaewitz) Input: sin 2 2θ 13 =0.058 δ CP = 270° sin 2 2θ 23 =1  0.06

26. European Strategy (Venice, december 03) 4 phases program for    and  1)CNGS/MINOS (2005-2010) 2) JPARC and Reactor(?) (2008-2013) 3) Superbeam/betabeam (>2014 ) 4) Neutrino factory (>2020 ) In any case a MW machine is central  Are Phase 3 (and 4) needed in case of a signal seen in JPARC  Can we disentangle all parameters with the superbeam /betabeam option  Should we go directly to phase 4 in case of no signal seen in JPARC shift in time for Superbeam/betabeam due to funding profile in Europe is the low energy the optimum choice to measure Θ 13, δ, sign(Δm 2 )  the choice on the strategy defines not only the needed R&D on accelerators but also for the detectors

27. Concluding on european activities (and dreams …) SPL330 EURISOL200 PS/SPS upgrade70 Decay Ring340 Super beam70 UNO like detector500 Grand total1510 Cost in Meuros no manpower, no contingencies could be provided by Nuclear physics Concluding remarks by CERN management at MMW CERN will reimburse LHC loan up to 2011 in 2008 new round of negotiations with members state for support for new R&D (not only neutrinos …) CERN machines (quite old) upgrade will cost Staff number will decrease from 2500  2000 in 5 years More international coordination is mandatory The choice will imply consequences on Machines AND Detectors R&D