1. A New Experiment To Measure θ 13 David Reyna Argonne National Laboratory

2. 10 March 2005David Reyna - ANL2 3 Flavor Mixing Matrix CKM Matrix MNS Matrix

3. 10 March 2005David Reyna - ANL3 Matrix Components: 3 Euler Angles ( θ 12 ; θ 13 ; θ 23 ) 1 CP phase ( δ ) (+2 Majorana Phases) Mixing Angles Solar ( ν e  ν x ) Atmospheric ( ν μ  ν x ) The Next Big Thing?

4. 10 March 2005David Reyna - ANL4 First observed by Ray Davis and collaborators. Measured by Super-K, SNO and KamLAND. Measured by Super-K and confirmed by Soudan2 and K2K. Unconfirmed observation by LSND, currently being investigated by MiniBooNE. Would require the existence of sterile neutrinos or CPT violation. Current Experiments

5. 10 March 2005David Reyna - ANL5 Δm 2 (aka: LSND problem) For 3 ν only 2 independent mass differences Mass hierarchy unknown (  m 2 solar ~ 7 x 10 -5 eV 2 ) (  m 2 atm ~ 2 x 10 -3 eV 2 ) NormalInverted m2m2 m2m2 m1m1 m3m3 m3m3 m1m1 m2m2

6. 10 March 2005David Reyna - ANL6 Current  13 Bound In currently allowed range (Δm 2 =1.3-3 x 10 -3 eV 2 ) sin 2 (2θ 13 ) < 0.19 @ 90% CL Current Limits are set by experiments which were not trying to measure θ 13 Optimization of the experiments for this goal was never done

7. 10 March 2005David Reyna - ANL7 How to Measure  13 Appearance measurement –Accelerator measurements look for small ν e appearance in ν μ beam P(   e sin 2 (2 13 )sin 2 ( 23 )sin 2 (m 2 atm L/4E) Disappearance measurement –Reactor measurements look for small ν e disappearance from large isotropic flux P( e  e ) = 1 - sin 2 (2 13 )sin 2 (m 2 atm L/4E)

8. 10 March 2005David Reyna - ANL8 Accelerator Difficulties Signature is electron appearance –Requires massive detector with fine granularity (be able to distinguish e from P) Backgrounds – e in the beam, (~1%, from K  e3, K 0 e3 ) –Fake e from  e, (at high energy) –Showers which look like e ’ s, particularly  ,    Measurement has degeneracies due to cp-violation and matter effects

9. 10 March 2005David Reyna - ANL9 e Appearance in a  beam P(   e ) = (2c 13 s 13 s 23 ) 2 sin 2     8c 13 s 12 s 13 s 23 (c 12 c 23 cos  s 12 s 13 s 23 )cos  32 sin  31 sin  21  8c 13 c 12 c 23 s 12 s 13 s 23 sin  sin  32 sin  31 sin  21  4s 12 c 13 (c 12 c 23  s 12 s 23 s 13  c 12 c 23 s 12 s 23 s 13 cos  sin 2  21  c 13 s 13 s 23  s 13  aL  E  cos  32 sin  31         a = constant X n e E CP violating CP: a  -a,   

10. 10 March 2005David Reyna - ANL10 sin 2 2  13  ~sin  ~cos  There are 2 Observables P(   e ) P(   e ) Interpretation in terms of sin 2 2  13,  and sign of  m 2 23 depends on the value of these parameters and on the conditions of the experiment: L and E Minakata and Nunokawa, hep-ph/0108085 Understanding the Degeneracy

11. 10 March 2005David Reyna - ANL11 Experimental Solutions If θ 13 is large, the degeneracy can be broken with Off-Axis measurements –Measure both ν and anti- ν rates –Multiple experiments with different baselines and different energies –Will yield a rich physics program for cp-phase and mass hierarchy If θ 13 is zero, degeneracies collapse but there’s no attainable physics gain Big cost - big risk

12. 10 March 2005David Reyna - ANL12 P( e  e ) = 1 - sin 2 2 13 sin 2 (m 2 atm L/4E) - cos 4  13 sin 2 2 12 sin 2 (m 2 sol L/4E) The Reactor Measurement P L/E(km/MeV) atmospheric solar No CP-violation in a disappearance measurement Distance (~1Km) is too short for matter effects

13. 10 March 2005David Reyna - ANL13 Previous Reactor Measurements All measure the same energy spectrum. Previous experiments used single detector and were limited by 3% uncertainty in reactor power. KamLAND is first to see positive evidence of oscillation. Future experiments propose 2+ detectors of 10-100 tons (not kilotons). KamLAND sees a 40% deficit/shape at 200km related to  m 2 12 Search for a 1-5% deficit/shape at ~1 km related to  m 2 13

14. 10 March 2005David Reyna - ANL14 p p e+e+  e-e- e+e+   511 keV n n p  2.2 MeV ~200 s How to Detect a e Event

15. 10 March 2005David Reyna - ANL15 Reactor ’s Reactors provide a fairly steady flux of 1-10 MeV ’s Neutrino energy carried by positron E ν = E e+ + 0.8 MeV Adding Gd moves n-capture peak from 2.2 MeV to 8 MeV and reduces capture time to ~10 μ s a)ν e interactions in detector ‡ [day MeV] -1 b)ν e flux at detector ‡ [10 8 /(s MeV cm 2 )] c)σ(E ν ) [10 -43 cm -2 ] ‡ from Palo Verde

16. 10 March 2005David Reyna - ANL16 8.4 GW th Chooz PWR power station Near detector Far detector e e, ,  D 1 = 100-200 m D 2 = 1,050 m The Double Chooz Concept Measure neutrino flux before and after oscillation Measure difference from 1/r 2 dependence Improve detector design to reduce systematics

17. 10 March 2005David Reyna - ANL17 Who is Double Chooz? Saclay, APC, Subatech, TUMunich, MPIK-Heidelberg, Tubingen Univ., Univ. Hamburg, Kurchatov, LNGS, Lousiana State, Argonne, Drexel Univ. Alabama, Univ. Notre Dame, Kansas State, Univ. Tennessee

18. 10 March 2005David Reyna - ANL18 Chooz-near Chooz-far EdF Has Approved Access to All Sites

19. 10 March 2005David Reyna - ANL19 Far Near Sites 250 m 125 m 67,5 - 80 200 55 - 65 150 45 - 53 100 Required overburden (m.w.e) Distance Reactor- detector 60 m.w.e. overburden 12 m compacted earth 3 meter high density material DAPNIA

20. 10 March 2005David Reyna - ANL20 Reactor Challenges Long term stability (Liquid Scintillator) –Chooz/Palo Verde were few month exp’s –Next generation must be 3-5 years Backgrounds –Chooz measured ~10% with reactor off –Unlikely to duplicate reactor off data Systematic Error Control –Consistency of mechanical construction –Previous exp’s were 2-3% (excluding reactor) –Needs to be 1% or less

21. 10 March 2005David Reyna - ANL21 Long Term Stability (Liquid Scintillator) Gd doping has resulted in poor stablity of liquid Scintillator –Palo Verde had problems with precipitation/condensation Mystical fix with water vapor –Chooz saw a very rapid decay of attenuation length Heidelberg and LNGS (LENS/Borexino) have been working for the last 3-5 years to understand these effects –Simple dissolved Gd solutions are very sensitive to pH –Attempting to bind Gd into the chemical structure of the liquid Eur.Phys.J. C27 (2003) 331-374

22. 10 March 2005David Reyna - ANL22 Gd doped scintillator Gd-Acac Gd-Dmp 3+ Gd ( R-COOH) x R-COO- -OOC-R Gd-Carboxylate Solvant: 20% PXE – 80% Dodecane Gd loading: 3 recipes developed @Heidelberg & LNGS Gd-CBX Good stability @20 o C Suitable baseline – End of development Gd-Acac Good stability @20 o C Low solubility in PXE  warning Difficult to purify Gd-Dmp Good stability @20 o C High solubility in PXE+dodecane OK for purification Synthesis to optimize 6 g/l PPO 20 mg/l BisMSB LY~8000 /MeV L = 5-10 m

23. 10 March 2005David Reyna - ANL23 20C - long period test –All Gd-CBX,Acac, Dmp are stable –Yb sample stable since 4,5 years (small sample) –In sample stable since 1,5 years (2 liters, 1 year meas. @LNGS) Gd-CBX Gd-Acac HeidelbergGd-CBX (test in Saclay) Gd Doped Scintillator Aging Tests High Concentration Test –LENS R&D: Yb, Gd, In  2 In-sampled loaded at 5% measured for 1 year @ LNGS and found stable (10-20% error) – 6 month 1% Gd-CBX Stable  work in progress High Temperature Test –40C for several weeks to accelerate aging –Still under investigation Next Step: large scale production and stability test

24. 10 March 2005David Reyna - ANL24 Backgrounds n Gd  ~ 8 MeV n deposits energy correlated background accidental background (uncorrelated) n Gd  ~ 8 MeV +  E  >~ 1 MeV +  -n cascades Accidental Backgrounds –Mainly at Low E –Best measurement from Borexino(CTF) –Must reduce few MeV radioactive sources and thermal neutrons Correlated Backgrounds –Mainly from cosmic muons –Best measurements from KamLAND but hard to extrapolate to shallow depth –Must reduce overall muon rate and attempt to veto background candidates

25. 10 March 2005David Reyna - ANL25 Spallation fast neutron μ capture Recoil p n capture on Gd Gd Recoil p n from  capture μ μ Cosmic muons create fast neutrons –Spallation in the rock surrounding the detector –Muon capture in the detector materials Fast neutron slows down by scattering into the scintillator (depositing energy) and is later captured on Gd ! Full simulation – Geant + Fluka –Old Chooz configuration: 300 m.w.e. 31hours – to validate MC Simulated: N b <1.6 evts/day (90% C.L.) Measured in-situ: N b =1.1 evts/day –Double-Chooz configuration: 338 106 μ tracked – 580 103 neutrons tracked 1 neutron created a background event Far detector expectation: N b <0.5 evt/day (90% C.L.) Near detector expectation: N b <3.2 evts/day (90%C.L.) Neutron Induced Background

26. 10 March 2005David Reyna - ANL26  crossing the detector Likely to be seen by the Veto 8 He 9 Li 11 Li β decayed followed by n emission within 200 ms ! (not veto-able) μ interaction on 12 C β-neutron Cascades (Cosmogenics)

27. 10 March 2005David Reyna - ANL27 Chooz Backgrounds Large singles rate –PMT glass in scintillator –Used vertex cut to reduce effect but with increased systematic error –New detector design will eliminate this effect Took data with all reactors off –Allowed direct measurement of correlated backgrounds –Consistent with other analysis methods for eliminating backgrounds –Known environment for future experiment Eur.Phys.J. C27 (2003) 331-374

28. 10 March 2005David Reyna - ANL28 Background Estimates Chooz (300 mwe) 5.5 m 3, Noise/Signal ~ 4% –Correlated events (neutrons): Chooz : ~1 recoil proton per day Double-Chooz-Far (300 mwe)12.7 m 3, Signal x 2.4 –Uncorrelated (, + n capt. on Gd):Sx3 & N/3  can be subtracted –Correlated events (neutrons): Goal <1 events per day + known spectrum  N/S<~1% –Correlated events (cosmogenics) Double-Chooz-near (60 mwe) 12.7 m 3, Signal x 30-50 S FAR –Key advantage: D near ~150 m  Signal x ~30-50 –Uncorrelated: Chooz-Far backgrounds x 50  can be subtracted –Correlated events: Chooz-Far x <30  N/S < 1% –Correlated events (cosmogenics) (but not a comprehensive list of backgrounds …)

29. 10 March 2005David Reyna - ANL29 Additional Outer Veto at Near Detector Simulated Veto Efficiency (55 Million Events) 36283Events with Target Neutron(%) 21552No Muon in Target0.6 2218No Inner Veto Muon0.06 1174No Outer Veto hit on top0.03 46With no Outer Veto Hit0.001

30. 10 March 2005David Reyna - ANL30 7 m Shielding: 0,15 m steel 7 m Muon VETO: scintillating oil (r+0.6 m – V = 110 m 3 ) Non-scintillating buffer: same liquid (+ quencher?) (r+0.95m,, V = 100 m 3 )  -catcher: 80% dodecane + 20% PXE (acrylic, r+0,6m – V = 28,1 m 3 ) PMTs supporting structure target: 80% dodecane + 20% PXE + 0.1% Gd (acrylic, r = 1,2 m, h = 2,8 m, 12,7 m 3 ) n e p Gd  ~ 8 MeV 511 keV e+e+ New detector design

31. 10 March 2005David Reyna - ANL31 Systematic Breakdown Error SourcePalo VerdeBugey Abs Norm Bugey Rel Norm Neutrino Flux3.32.8- νP Cross Section1.00.2- Solid Angle0.30.5 Target Protons1.31.90.6 Neutron Detection2.03.21.5 Positron Detection2.00.9 Selection Correlation1.9-4.51.0- Background3.5-3.9‡‡ Total5.3-6.95.02.0 25 @ 15m ‡ Signal/Background = 2.2 @ 40m 0.7 @ 95m

32. 10 March 2005David Reyna - ANL32 Detector Relative Comparison Solid angle –Distance measured @10cm + Monitoring of the source barycenter … Target volume –@CHOOZ : 0.3% [simple measurement] –Goal ~0.2% [same apparatus for both detectors] – –Test - scale 1 - in progress Density –0.1% achievable, but accurate temperature control mandatory H/C ratio & Gd concentration –Absolute measurement is difficult : 1% error @CHOOZ –Plan: use the same batch to fill both detectors Boundary effect at the inner vessel interface (spill in/out) –Neutron transport slightly different due to solid angle effect Live time to be measured accurately by several methods

33. 10 March 2005David Reyna - ANL33 e+e+ n tt n e p Gd e+e+ Relative Normalization: Analysis @Chooz: 1.5% syst. err. –7 analysis cuts –Efficiency ~70% Goal Double-Chooz: ~0.3% syst. err. –2 to 3 analysis cuts Selection cuts –neutron energy –distance (e+ - n ) [level of accidentals] –t (e+ - n)

34. 10 March 2005David Reyna - ANL34 How Good is Good Enough? Double Chooz Goal Original Chooz Detector Error

35. 10 March 2005David Reyna - ANL35 Understanding Mechanical Construction Acrylic Target vessel (R=1,2m, h=2,8m, t = 12mm) Stainless steel Buffer (R= 2,75m, h = 5,6m, t = 4mm) Muon VETO (shield) Thickness = 150mm Acrylic Gamma catcher vessel (R = 1,8m, H = 4 m, t = 8mm) LS + 0,1%Gd LS

36. 10 March 2005David Reyna - ANL36 Acrylic selected Material compatibility test ongoing –(OK with Security Factor = 8) Prototype 1/5 by june 2005 –(call for bid sent) A special Tool will be developed to rotate/insert the acrylic vessel into the pit after PMT mounting CEA/DAPNIA Test of accessibility in Chooz tunnel with acrylic vessel model Acrylic Integration

37. 10 March 2005David Reyna - ANL37 Mechanical Studies VesselDimensionDistortionStress Inputs : Target thickness = 8 mm  catcher thick. = 12 mm E = 2.7 GPa Elastic limit : ~80 MPa Loads = dead load Max. distortion : <1 mmMax. VM stress: 1 MPa Inputs : Thickness = 4 mm E = 210 GPa Elastic limit: 205 MPa Loads = 2 kg / pmts acrylic vessels weight dead load Max. distortion : 4.1 mmMax. VM stress: 23 MPa

38. 10 March 2005David Reyna - ANL38 Acrylic Target Vessel Stainless Steel Buffer Muon VETO Acrylic Gamma Catcher Vessel LS + 0,1%Gd LS Goal: technical solutions for construction and integration Scale (1:5) Prototype PMT Cable Routing

39. 10 March 2005David Reyna - ANL39 Additional Work Ongoing PMTs –Testing radioactivity –Mounting systems Electronics/HV –Prototype designs are under study –DAQ system is under design Calibration –Fiber Optic/LED system –Articulated arm vs. Rope-and-Pulley development –Wire driven Guide Tubes for Gamma Catcher –Radioactive source development Simulation –Full G4 Detector Simulation (derivative of KamLand) Complete optical properties All Chemical Properties –Muon/fast neutron in G4 and FLUKA –Feeding back the R&D into the simulation effort Non-Proliferation –Collaboration with LLNL and IAEA –Interest in monitoring reactor power and fuel composition

40. 10 March 2005David Reyna - ANL40 Status of Double Chooz (Europe - I) EDF has agreed to the project –Allow use of the original laboratory –Agreed to location for near laboratory (150-200 meters from core) French funding agency has approved the project –Provide ½ the funding for detector construction –Agreed to fund the construction of the near laboratory Awaiting complete engineering analysis and costs from EdF –Contracts for prototype construction are already under negotiations for bids MPI-Heidelberg is providing independent funding for Liquid Scintillator development and production

41. 10 March 2005David Reyna - ANL41 Status of Double Chooz (Europe - II) Germany still has other institutions seeking ‘normal’ funding –5 year cycle but they are in the queue Italy is working on LS but has no funding –Rumors that the canceled BTeV may free up Italian money Russians have agreed to produce radioactive sources but little money is expected

42. 10 March 2005David Reyna - ANL42 Status of Double Chooz (U.S.) Submitted proposal to DOE in October ‘04 –$4.8M over 3 years for total project –Already secured forward funding of $3M –DOE has decided to not decide Establishing neutrino SAG Double Chooz Construction Proposal competes with R&D requests from Braidwood and Daya Bay US groups are continuing to finalize design work on expectation of approval New groups are continuing to join –Recent additions of Los Alamos and Livermore

43. 10 March 2005David Reyna - ANL43 Expected Schedule Detector Construction –Can begin in 2006 (No known reason for delays in construction and installation of far detector) Near Laboratory –Finalize designs in 2005 –Hope to have civil construction 2006-7 –Install near detector at end of 2007 or early 2008 Data Taking –Can begin taking data with far detector as soon as it is installed (middle 2007) –Near detector will hopefully follow in 16 months 2003 200420052006200720082009 SiteData takingProposalConstruction ?& design Far detector starts Near detector starts

44. 10 March 2005David Reyna - ANL44 Far detector only Far & Near detectors together 05/2007 05/200805/2009 05/2010  sys =2.5%  sys =0.6% Expected Sensitivity 2007-2012 Far Detector starts in 2007 Near detector follows 16 months later Double Chooz can surpass the original Chooz bound in 6 months 90% C.L. contour if sin 2 (2  13 )=0  m 2 atm = 2.8 10 -3 eV 2 is supposed to be known at 20% by MINOS

45. 10 March 2005David Reyna - ANL45 Double Chooz Complements Off-Axis A positive signal within the Double Chooz range would signify a very rich program at the accelerator measurements A null result would imply a difficult path Double Chooz is the only experiment which can provide such a direct result in a short time period (~3-4 years) Sensitivity regions for resolving the Mass Hierarchy at 2 (with Proton Driver) from M. Shaevitz

46. 10 March 2005David Reyna - ANL46 Conclusion & outlook Strong Collaboration –Saclay, APC, Subatech, TU Munich, MPIK-Heidelberg, Tubingen Univ., Univ. Hamburg, Kurchatov, Lousiana State, Drexel, Argonne, Univ. Alabama, Univ. Notre Dame, Kansas State, Univ. Tennessee, LNGS –Experience from Chooz, Palo Verde, KamLAND, Borexino, LENS Known Technology –Conservative design (incremental improvement on Chooz) –Reasonably achievable improvements in detector systematics Known Environment –Direct comparison to previous Chooz results / backgrounds Excellent Physics Opportunity –Current Chooz bound is sin 2 (2 13 )<0.19 @ 90% C.L –Expect sensitivity of sin 2 (2 13 )<0.02-0.03 with 3 to 5 year run –Continuing to maintain aggressive schedule –Price is right!