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CS-IN2P3 20-21 Mars 2006 Thierry Lasserre (CEA/Saclay & APC) Pour la collaboration Double Chooz

CS-IN2P3 20-21 Mars 2006 Thierry Lasserre (CEA/Saclay & APC) Pour la collaboration Double Chooz. Collaboration. + Spain CIEMAT.  e   e ( disappearance experiment) P th = 8.4 GW th , L = 1.050 km, M = 5 t overburden: 300 mwe.  sol.  atm.  13 , .

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CS-IN2P3 20-21 Mars 2006 Thierry Lasserre (CEA/Saclay & APC) Pour la collaboration Double Chooz

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  1. CS-IN2P3 20-21 Mars 2006 Thierry Lasserre (CEA/Saclay & APC) Pour la collaboration Double Chooz

  2. Collaboration + Spain CIEMAT Th. Lasserre CSIN2P3 20/03/06

  3. e e (disappearance experiment) Pth= 8.4 GWth, L = 1.050 km, M = 5 toverburden: 300 mwe sol atm 13,  Limit on 13 from Chooz @m2atm = 2 10-3 eV2 sin2(2θ13)  0.2 (90% C.L) R = 1.01  2.8%(stat)2.7%(syst) M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374 Th. Lasserre CSIN2P3 20/03/06

  4. 13& reactor experiments • <E> ~ a few MeV  only disappearance experiments  sin2(213) measurement independent of -CP • 1-P(e e) = sin2(213)sin2(m231L/4E) + O(m221/m231) •  weak dependence in m221 • a few MeV e + short baselines  negligible matter effects (O[10-4] )  sin2(213) measurement independent of sign(m213) 13 & beam experiments Appearance probability :  dependences in sin(223), sin(23), sign(m231), -CP phase in [0,2] Th. Lasserre CSIN2P3 20/03/06

  5. Near detector Far detector Concept of the experiment Th. Lasserre CSIN2P3 20/03/06

  6. Rate + shape information e e,, Far/Near energy bin ratio @1,05 km Oscillation signal & Baseline Far detector 10.3 m3 Near detector 10.3 m3 Nuclear reactor 2 cores: 4.27 GWth D = 1050 m D~280 m • Isotropic e flux (uranium 235,238 & plutonium 239, 241 fission fragments) • Detection tag : e + p  e+ + n, <E>~ 3 MeV, Threshold ~1.8 MeV • Disappearance experiment: • Rate modification • Energy spectrum shape distortion Th. Lasserre CSIN2P3 20/03/06

  7. Site in Ardennes, France Th. Lasserre CSIN2P3 20/03/06

  8. Chooz-far Chooz-near Site in Ardennes, France Th. Lasserre CSIN2P3 20/03/06

  9. ~30 m DAPNIA Far site Near site  flux x ~10 ~250 m ~70-80 m.w.e 1000 events/day (preliminary) Flat topology approximation Start of integration 2006 1.05 m 300 m.w.e 70 events/day Available end of 2008 ? Th. Lasserre CSIN2P3 20/03/06

  10. Detector Systematics Th. Lasserre CSIN2P3 20/03/06

  11. Accidental backgrounds Material radiopurity CHOOZ measured n rate Not reproduced by simulation Rdelayed~45 n/h Double Chooz n rate Conservative esimation Rdelayed~83 n/h Conservative estimation Rprompt < 10Hz Raccidental < 2/d Can be measured with 10% precision Th. Lasserre CSIN2P3 20/03/06

  12. μ μ μ capture n from  capture Recoil p Gd Gd Recoil p n capture on Gd Spallation fast neutron Fast Neutrons &  Capture  Capture Estimation Double-Chooz Dead materials Target+GC Buffer Vessel Buffer Oil Steel shield Chimney Far : 0.06/d Near : 0.42/d Inner+Outer Veto Error ~50% Fast Neutrons Full simulation Geant + Fluka CHOOZ Dominant bkg Simulated: 0.8/d Measured: ~ 1/d Simulation is reliable Double Chooz (simulation) Far : 0.15/d Near : 1.4/d Measure in-situ Error ~100% Th. Lasserre CSIN2P3 20/03/06

  13. events Chooz data Fast neutron 9Li μ interactionon 12C MeV 9Li spallation background  crossing the detector Likely to be seen by the Veto CHOOZ Total Chooz rate: fast neutrons + 9Li  <0.6/d from CHOOZ data fit (non official analysis of CHOOZ data) Double Chooz Scaling from Chooz Far: 1/d & Near: 7/d Inner/Outer Veto + Reactor Off? β decayed followed by n emission, =178 ms Th. Lasserre CSIN2P3 20/03/06

  14. Background Summary 9Li Accidentals Fast neutron Th. Lasserre CSIN2P3 20/03/06

  15. Computation of the Sensitivity OiA : event number in the i-th bin at the A detector TiA: theoretical event number in the i-th bin at the A detector (with oscillation parameter) TiA: systematic and background terms Backgrounds • 1% subtraction error Uncorrelated between Near/Far Uncorrelated between Energy bins Or • Background shape + rate Rate + Shape error Systematics σabs = 2.0 % σrel = 0.6 % σshp = 2.0 % σΔm2= 10.0 % σE = 7 %@1 MeV Th. Lasserre CSIN2P3 20/03/06

  16. Sensitivity & luminosity (GW.ton.year) • Background subtraction error • - Included as a bin-2-bin error • - Impact depends on luminosity • Double Chooz < 5 years • 0.5%-2% difference • Modest impact on sensitivity • Double Chooz > 10 year • 0.5%-2% différence • Crucial for 2nd génération of • reactor experiments Th. Lasserre CSIN2P3 20/03/06

  17. Sensitivity & m2atm (90% C.L.) 3 years of data with both detectors Systematics included σabs = 2.0 % σrel = 0.6 % σshp = 2.0 % σΔm2= 10.0 % σE = 7 %@1 MeV Th. Lasserre CSIN2P3 20/03/06

  18. Discovery potential & m2atm (3) 3 years of data with both detectors Systematics included σabs = 2.0 % σrel = 0.6 % σshp = 2.0 % σΔm2= 10.0 % σE = 7 %@1 MeV Th. Lasserre CSIN2P3 20/03/06

  19. Near Detector Location • Uncorrelated fluctuations included • Relative Error : 0.6% • Spectral shape uncertainty 2% • m2 known at 20% • Power flucutation of each core: 3% Suitable area ~277 m 3 years data taking Th. Lasserre CSIN2P3 20/03/06

  20. Optimum Baseline & m2atm 3 years of data with both detectors Near detector distance: 280 m Systematics included: • σabs = 2.0 % • σrel = 0.6 % • σshp = 2.0 % • σΔm2= 10.0 % Resolution : σE = 7 %@1 MeV Oscillation parameters chosen: • Δm231 = 2.0-3.5 10-3 eV2 • sin2(2θ13)=0 @1,05 km Double Chooz optimized for m2atm>2.5 10-3 eV2 But @m2atm=2.0 eV2, sensitivity decreased to 25% with respect to optimium @1,05 km Dn Df Th. Lasserre CSIN2P3 20/03/06

  21. Sensitivity & Relative Error 3 years of data with both detectors Systematics included σabs = 2.0 % σshp = 2.0 % σΔm2= 10.0 % σE = 7 %@1 MeV m2=2.5 10-3 eV2 Th. Lasserre CSIN2P3 20/03/06

  22. A Realistic Scenario 90% C.L. contour if sin2(2)=0 m2atm = 2.5 10-3 eV2 is supposed to be known at 20% by MINOS • Efficiencies included • 1% background subtr. • Systematics: • - σabs = 2.0% • - σrel = 0.6% • - σscl = 0.5% • - σshp = 2.0% • - σΔm2= 20% Far detector only Far & Near detectors together sys=2.5% sys=0.6% • rate info only: no-osc excluded @ 2.66σ • Rate+shape info: no-esc excluded @ 5.98σ Exemple: sin2(213)=0.10

  23. Complementarity with Superbeams 3 discovery potential 3 sensitivity (no signal) Th. Lasserre CSIN2P3 20/03/06

  24. Towards CP- experiments Th. Lasserre CSIN2P3 20/03/06

  25. Summary • Relative Systematic Error Goal: @0.6% • Achievable “intrinsically” by using 2 identical detectors • Similar estimation as KASKA - Second generation projects aim at 0.3% • Backgrounds • Correlated bkg will dominate as in CHOOZ • Upper bound given by CHOOZ (real) data • Double CHOOZ sensitivity: • Far Detector ONLY: sin2(213)<0.06-0.1 (after 1 year) • sin2(213)<0.02-0.03 (3 years, 2 detectors) • Complementarity with the Beam programs • Future oscillation physics based on 13 true value! An early 13 information would boost the program towards -CP Optimisation of Neutrino/Antineutrino run of superBeams experiments • Reactor/Accelerator provide 2 independent measurements Double Chooz (far) will tell wether second generation of reactor neutrino is feasible (Daya Bay, Braidwood, Angra) Th. Lasserre CSIN2P3 20/03/06

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