1. Double-CH  13  13 Z H. De Kerret (APC) On behalf the Double-Chooz proto-collaboration June 9 2004

2. e  e (disappearance experiment) P th = 8.5 GW th, L = 1,1 km, M = 5t overburden: 300 mwe Best current constraint: CHOOZ World best constraint ! @  m 2 atm =2 10 -3 eV 2 sin 2 2θ 13 < 0.2 (90% C.L) e   x R = 1.01  2.8%(stat)  2.7%(syst) M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374

3. The Double-CHOOZ concept CHOOZ power station Near detector Far detector D 1 = 100-200 m D 2 = 1050 m e e, ,  anti- e flux (uranium 235, 238 & plutonium 239, 241) Reaction: e + p  e + + n, ~ 4 MeV, E thresholdl =1.8 MeV Dissapearance experiement Search for a departure from the 1/D 2 behavior

4. CHOOZ site & Detector Overview e

5. Near site: D~100-200 m, overburden 50-80 mwe Far site: D~1.1 km, overburden 300 mwe TypePWR Cores2 Power8.4 GW th Couplage1996/1997 (%, in to 2000)66, 57 ConstructeurFramatome OpérateurEDF V=2 x 12,67 m 3, D p =100-200m, D l =1050m Chooz-Far Chooz-Near Double-Chooz, Ardennes, France

6. The CHOOZ-near site 250 m 125 m Near detector @100-200 m from the cores Exact position under study, in collaboration with EDF

7. Detect the antineutrino Energy measurement of the e+, => E Neutron capture on Gd, E D ≈8 MeV Correlations: - time :   30  s - space 3e : < 1m 3 The target is the active medium : - liquid scintillator loaded at ≈ 0.1 % en Gd Important progress from LENS e + p  e + + n

8. The CHOOZ-near detector ~5- 15 m Dense material ~10-20 m Distance Reactor-detector Overburden (m.w.e) 100 45 - 53 150 55 - 65 200 67,5 - 80

9. Detector design A scintillating buffer around the target (to see the gammas from positron capture and Gd decays) ~60 cm A non scintillating buffer in front of pmts (reduce the single rates) ~ 1m A muon veto Increase as much as possible the active buffer for the fast neutrons coming from outside

10. The CHOOZ-far detector Existing pit non-scintillating buffer: same liquid (+ quencher?) (r+0.95m,, V=100 m 3 )  -catcher: 80% dodécane + 20% PXE (acrylique, r+0,6m – V= 28,1 m 3 ) 7 m PMTs supporting structure Muon VETO: scintillating oil (r+0.6 m – V=110 m 3 ) 7 m shielding: 0,15m steel target:80% dodécane + 20% PXE + 0.1% Gd (acrylix, r=1,2m, h = 2,8m, 12,7 m 3 )

11. Scintillator Overview

12. Goal: 0.1% Gd loaded scintillator Light yield ~8000  /MeV + attenuation length > 5m STABLE Compatible with acrylic R&D LENS 1998-2004 Carboxylate based scintillator Beta dikitonates based scintillator Gadolinium doped scintillator Gd-Acac 3+ Gd ( R-COOH) x R-COO- -OOC-R Carboxylate

13. Scintillator development Volume [m 3 ]Type -target12,70,1% Gd loaded scintillator  -Catcher28,1Unloaded scintillator Buffer100Non scintillating oil Veto110Scintillating oil Baseline - PC (C 9 H 12 ), PXE (C 16 H 18 ) attack acrylics - Dodécane + PXE more resistant … - R&D Saclay+MPIK+Gran Sasso (08/2004) Baseline: 80% dodecane + 20% PXE + 6 g/l PPO + 20 mg/l BisMSB + 0.1% Gd LY~8000  /MeV, L = 5-10 meters Flours concentration - Match scintillation light to PMTs - PPO : 6g/l - BisMSB: 20mg/l Gd-ACAC

14. Scintillator R&D R&D 1/ Long term stability  20042/ scintillator-acrylic compatibility Ageing test @50 o (Saclay, Gran Sasso/INR, MPIK) Material compatibility test (Saclay, MPIK) Saclay  acrylic envelop design in progress (scintillator tests, Saclay) First ageing test @40 o, 50 o (Caroxylates, Gran Sasso / INR)

15. Sensitivity & Discovery Potential

16. Description of the simulation Analyse standard Expected events / bin i: N i A ( sin 2 (2  13 ) gen ) Tested spectrum O i A : Theoretical prediction : T i A = (1 + a + b A + c i ) x N i A ( sin 2 (2  13 ) rec )

17. 90% C.L. sensitivity if sin 2 (2  13 )=0  m 2 =2.0 10 -3 eV 2 3 years (efficiency included) sin 2 (2  13 )<0.03  m 2 =2.4 10 -3 eV 2 3 years (efficiency included) sin 2 (2  13 )<0.024

18. Relative normalisation error  m 2 =2.0 10 -3 eV 2 3 years (efficiency included)

19. Th. Lasserre Influence of flat backgrounds

20. Th. Lasserre Influence of the shape error

21. Lindner’s analysis of Double-CHOOZ sensitivity

22. e 12.7 tons, 3 years 340 tons, 3 years P. Huber et. al. hep/0403068

23. Attempt to compare Double-Chooz with Beams & Superbrams P. Huber et. al. hep/0403068 Double-CHOOZ starts with two detectors on 01/01/2008 T2K starts at FULL intensity on 01/01/2010  m 2 =2.0 10 -3 eV 2

24. e oscillation @Double-CHOOZ @1,05 km e

25. Spectrum deformation @Double-CHOOZ sin 2 (2  13 )=0.15

26. Double-CHOOZ discovery potential Th. Lasserre

27. Double-CHOOZ discovery potential

28. I Compare Double-Chooz & T2K (limite @90% C.L.)

29. Attempt to compare Double-Chooz with T2K (3σ discovery potential) sin 2 2θ 13 = 0.14 sin 2 2θ 13 = 0.08 sin22θ 13 = 0.04

30.    gen    (fit) Energy scale modified on both detectors by +1% Strong distortion Use a 1 parameter fit for all the rest Energy scale

31. Position of the near detector Moving the Close detector by +0.5m Distance to reactor increases Dist to Far decreases

32. 235 U 239 Pu 238 U 241 Pu  fit   gen  Burn-up effect (330 days fuel evolution) First day day 330

33. Proto-collaboration, Letter of Intent and prospects e

34. The current proto-collaboration Chooz, November 2003 Double-CHOOZ meetings Chooz, November 2003 Heidelberg, February 2004 Tubingen, April 2004

35. Letter of Intent

36. Double-Chooz & IAEA IAEA :Intenational Agency for Atomic Energy Missions: Safety & Security, Science & Technology, Safeguard & Verification Control that member states do no use civil installations with military goals (production of plutonium !) Control of the nuclear fuel in the whole fuel cycle * Fuel assemblies, rods, containers * (*Anti-neutrinos could play a role!) Distant & unexpected controls of the nuclear installations * Why IAEA is interested to antineutrino ? IAEA wants the « state of the art »methods for the future ! Several futuristic methods under study Kr, I, Cs gas trace in atmosphere Cost issue … AIEA wants a feasibility study on antineutrinos - Monitoring of the reactors with a Double-Chooz like detector ? - Monitoring a country – new reactors “à la KamLAND” CEA/Saclay  we already ask some support for: - Double-Chooz near detector - New nuclear physics program to improve knowledge of reactor spectrum

37. Improving CHOOZ – Statistical error - increase luminosity L =  t x P(GW) x V cible @CHOOZ: R = 1.01  2.8%(stat)  2.7%(syst) CHOOZDouble-Chooz Target volume5,555 m 3 12,67 m 3 Number of free protons6,77 H/m 3 6,82 H/m 3 Data takingquelques mois3-5 years Rate26/d Far : 60/d Near: 3000/d Number of events2700 Far : 60 000/3 years Near: >3 10 6 /3 years Erreur stat2,7%0,4%

38. Decrease the total systematic error 1.Detector design 2.2 identical detectors  vers σ relative sys ~0,6% 3.Background – improve S/B>100  error<1% Improve CHOOZ – Systematic error - @CHOOZ : σ sys =2.8%

39. Detector simulation & calibration

40. Photons tracking 2 simulation indépendantes PCC & APC  simulation de CHOOZ (GEANT3) Kurchatov  simulation Borexino (GEANT4)

41. Photons tracking X [cm] Y [cm] Z [cm]Yield[%] 000100 0600101,0 01200102,5 01800109,6 060140102,3 0120140103,5 0150170104,8 0180200107,7  20% PXE + 80% dodécane + 0.1% Gd + 6g/l PPO + 20mg/l BisMSB  ~200 p.e./MeV with 500 PMTs – reflection coef =0%  Les PMs 8’’ are within the buffer ( glass at 25 cm inside)  Light collection ~flat (+5% maxi. in the target )

42. Systematic errors

43. Systematic error; « reactor » type Error typeCHOOZ New experiment Double-Chooz Réacteur Cross section0.2% O(0.1%) Antineutrinos1.9%<1.9%O(0.1%) Thermal power0.7%<0.7%O(0.1%) E/Fission0.6%<0.6%O(0.1%)  2.1%~2.1% O(0.1%) Systematic errors: « detector » type Error typeCHOOZ New experiment Double-Chooz Detector solid angle-0.2% Scintillator density0.3%0.1%O(0.1%) %H1.2%<1%O(0.1%) Target0.3%0.2% «Spill in/out»1.0% O(0.1%) Dead?0.25%<0.25% M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374 Same batch of scintillator for both detectors

44. Fast signal: positron E e+ (MeV) Non scintillating Buffer scintillanting buffer CHOOZ : only scintillanting buffer Detector = calorimter : positron energy is fully contained But accidental rate high  threshold on e+, many analysis cuts Double-CHOOZ : 1 Scintillanting buffer (60cm) + 1 Non-scintillanting buffer (95cm) Reduce the PMTs noise ( 40 K,Tl) E seuil hardware ~500 keV  No more thrshold cut  0% systematic ! 1.022 MeV calibration point at e+ spectrum start ( ) BDFs measuremnt above and below the positiron spectrum

45. Delayed signal : neutron Gd H H (H. de Kerret) E n (MeV) Gadolinium loaded scintillator (~0.1%) Gd  8 MeV  ’s (capture on Gd : 86.6%  1.0% in CHOOZ, Eur.Phys.J. C27 (2003) 331-374 ) H  2.2 MeV  ’s n capture prob.  1.0% (CHOOZ)  O% with 2 detectors (MC uncertainty)  t (e+-n)   0.4% (CHOOZ)  0% with 2 detectors (MC uncertainty) n energy   0.4% (CHOOZ)  Scintillating buffer mandatory (as in CHOOZ) “spill in / spill out” effect   1.0% (CHOOZ)  O(0.1%) 2 identical detectors needed!  But neutronics to be checked Non scintillating buffer Scintillating buffer

46. ErreurCHOOZ e+ seuil0.8% e+/géode (30cm)0.1% n capture1.0% Neutron énergie0.4% Distance n-géode (30 cm)0.1% Distance (e+-n)0.3%  t (e+-n)0.4% n multiplicity0.5%  1.5% M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374 Error typeCHOOZDouble-CHOOZ Distance (e+-n)0.3%0 - 0.2%Used or not ? En0.4%0.2%Calibration Cf  t (e+-n)0.4%0.1%electronics  -0.2-0.3% Cuts 6<En (MeV)<12 2<  n<100  s D<1-2m Analysis cuts @Double-CHOOZ Analyis cuts @CHOOZ

47. All systematic errors in Double-Chooz

48. R&D on systematic errors in 2004 Dead time (Heidelberg) - important (~50%) but simple (500microsec/muon) - generate couples of test particles et measure their survival time - hardware tests in 2004 Quantity of liquid in the target (Saclay) - build both targets in factory in the same time + test filling - geometrical measurements in factory and on site - weight liquids in the same intermdiate tank  0.1% Distance detector-reactor core(APC-Saclay ph.nucl.+Subatech?) - 10cm a 150 m  0.15% systematic error - 10cm in Chooz pub. (+- 3cm at Bugey) - core center of gravty movement of 6cm monitored at bugey

49. Background

50. - CHOOZ: S/B ~ 25 - Double-CHOOZ aim: S/B>~100 - Double-CHOOZ-far (300 mwe): 12.7 m 3  Signal x ~3 -Accidentals: Buffer non scintillanting buffers Double-Chooz: B/3  less than 0.5% and measurable -correlated events: CHOOZ: ~1 recoil proton / day & signal =26/d Double-CHOOZ: S* 2.3 & B/2  S/B>100 (neutronn simulation in progress) -Double-CHOOZ-near (~60 mwe): Signal x 50-100 S CHOOZ-loin -D proche ~100-200m  Signal * >30, but   * 30 - all backgrounds: BDF CHOOZ-loin * 100  Measure all BDFs at 50% Reduce backgrounds

51. I Accidental background S/B=350 S/B>10 3

52. Spallation neutrons Surrounded by 100 mwe rock shielding Simulation of neutrons from near-miss  (Geant4) Neutron produits dans la roche et transportés jusqu’au détecteurs (Fluka) Liquid buffers rejection Double-CHOOZ-far : simulation  <2/day Double-CHOOZ-near : thicker VETO 

53. Muon induced production of radioactive isotope IsotopeT 1/2 Emax (MeV) Rate (day -1 ) 300 mwe Rate (day -1 ) 20 m (50 mwe) Type -- 12 B0.02 s13.4--Uncorrelated 11 Be13.80 s11.5< 2< 23Uncorrelated 11 Li0.09 s20.8--Correlated 9 Li + 8 He 0.18 s13.6 2  0.321  4 Correlated 0.12 s10.6Correlated 8 Li0.84 s16.0414139  14Uncorrelated 6 He0.81 s3.514  1155  16Uncorrelated  +, EC 11 C20.38 m0.96770  498765  562Uncorrelated 10 C19.30 s1.998  121118  141Uncorrelated 9C9C0.13 s16.0414147  15Uncorrelated 8B8B0.77 s13.7616169  14Uncorrelated 7 Be53.3 d0.48196  202228  223Uncorrelated Rates are given for the CHOOZ 10 t PXE case (C 16 H 18 ) -Background: Production of radioactive nuclei on 12 C in the scintillator -NA54: Isotope production on 12 C target @SPS/CERN,  beam @100/190 GeV   (E)  E 0.73 (T. Hagner et. al.) Correlated events Dominated by  -n cascade,  ~few 100ms 8 He, 9 Li, 11 Li (instable isotopes)  to know: the ratio Li 9 /He 8 (Kamland?), trigger on the other branch of Li 9 (M.Cribier: 2 betas >3 MeV) measure li9 between 8 MeV and 11.9MeV  the shapes

54. calibration Same source used in both detectors gammas  1% de différence between the 2 energy scale  100 KeV at 6 MeV (0.2% systematic) Cf (neutron multiplicity)  <0.2% difference between the 2 neutron efficiencies Laser + fibres optical fiber pm stability, absorption length full scan of the target volume

55. Conclusion Détector and technology known (CHOOZ, BOREXINO, KamLAND, … Few R&D: liquid scintillator, cibles, systematic errors Proto-collaboration: Saclay,Nantes, APC, TUM, MPIK, Tubingen,Hambourg, Kurchatov, RAS, Italy,……… Letter of Intent  proposal fall 2004 Strong involvement of EDF (support of the plant management to get funding from the company direction) Detector cost: estimated to 7.25 Meuros ( without the civil engineering of the near detector) Approved in France (IN2P3 and CEA/saclay)  2-2.5 Meuros ( without the civil engineering of the near detector)  install the far detector in2006 & full data taking in early 2008