Jelena Maricic Drexel University. For Double Chooz Collaboration. Spain. France. Germany U.S.A. Japan Russia. Brazil U.K. Courtesy of T.

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1 Jelena Maricic Drexel University For Double Chooz Collaboration France Spain Germany U.S.A Japan Russia Brazil U.K. J. Maricic, Drexel U 1 Courtesy of T. Lasserre

2 ν e ν μ ν τ Neutrino Oscillations masses, angles and phase Repetitio est mater studiorum Repetition is the mother of learning. atmospheric s ij = sinθ ij c ij = cosθ ij solar c 13 0 s 13 e iδ c 12 s 12 0 = 0 c 23 s s 12 c s 23 c 23 s 13 e iδ 0 c θ atm θ 13, δ θ sol ν 1 ν 2 ν 3 δ phase is not known at all! θ 13 < 13 o θ 12 = 30 o θ 23 = 45 o Only the upper limit on the value of angle θ 13 has been set! Value of θ 13 directly influences prospects of measuring CP violation phase in the weak sector! While the oscillation angles govern the amount of mixing among different neutrino flavors, two neutrino mass differences Δm 212 and Δm 322 determine the oscillation pattern and have been measured: Δm 2 21=(7.59±0.21) 10 5 ev 2 Δm 2 32=(2.41±0.13) 10 3 ev 2 2

3 The Best Current Limit of θ 13 with Chooz Chooz experiment R = 1.01 ± 2.8%(stat)±2.7%(syst) World best constraint: CHOOZ experiment! (ν e ν e disappearance exp) ν e ν x M. Apollonio et. al., Eur.Phys.J. C27 (2003) atm = ev 2 sin 2 (2θ 13 ) < 0.2 (90% C.L) 3

4 θ 13 & Reactor Experiments <E ν > ~ a few MeV only disappearance experiments sin 2 (2θ 13 ) measurement independent of δ CP 1 P(ν e ν e ) = sin 2 (2θ 13 )sin 2 (Δm 2 31L/4E) + O(Δm 2 21/Δm 2 31) weak dependence in Δm 2 21 A few MeV ν e + short baselines negligible matter effects (O[10 4 ] ) sin 2 (2θ 13 ) measurement independent of sign(δm 2 13) Complementary to long baseline beam experiments that depend on dependences in sin(2θ 23 ), sin(θ 13 ), sign(δm 2 31), δ CP phase in [0,2π] 4

5 Reactor Neutrino Detection Signature Reactors are tremendous sources of neutrinos: N ν ( s 1 )= 6N Fiss s 1 ( ) Ps 1 P = 8GW N ν ~10 21 s 1 Neutrino detection: ( ) Gd + ~8 MeV Distinctive two step signature: prompt event Photons from e + annihilation E e = E ν MeV + O(E e /m n ) delayed event Photons from n capture on dedicated nuclei (Gd) Δt ~ 30 μs E ~ 8 MeV 5

6 Expected Backgrounds in Reactor Neutrino Experiments Accidental bkg: e + like signal: radioactivity from materials, PMTs, surrounding rock Rate=R e n signal: n from cosmic μ spallation, thermalized in detector and captured on Gd (R n ) Accidental coincidence Rate = R e x R n x Δt Correlated bkg: fast n (by cosmic μ) recoil on p (low energy) and captured on Gd long lived ( 9 Li, 8 He) β decaying isotopes induced by μ Bkg reduction and understanding of bkg is critical for oscillation measurement! 6

7 Improving CHOOZ? CHOOZ : R osc = 1.01 ± 2.8% (stat) ± 2.7% (syst) Statistical error More powerful reactor Target volume 5,55 m 3 (multi core) Target composition Data taking period Larger detection volume Event rate 2700 Longer exposure Luminosity increase L = Δt x P(GW) x Np Statistical error CHOOZ 6, H/m 3 Few months 2,7% Double Chooz 10,3 m 3 6, H/m years Far: /3 y Near: ~500,000/3 y 0,5% Systematic error: ν flux and cross section uncertainty Multi detector Identical detectors to reduce inter detector systematics (goal: towards σ relative ~0,6%) Background induced errors Improve detector design larger S/B Increase overburden Improve bkg knowledge by direct measurement subtraction error < 1% 7

8 The New Concept 2 detectors P(ν e ν e ) = 1 sin 2 (2θ 13 ) sin 2 (Δm 2 31L/4E) Near detector Far detector e + spectrum Far Detetector Stat. Errors Far to near detector signal ratio will give information about θ 13 Far/Near ratio ν e ν e,µ,τ sin 2 (2θ 13 )=0.12 ν e,μ,τ Nuclear Power Station Near detector Far detector 400 m 1050 m Δm 2 atm= ev 2 8

9 Site in French Ardennes 300 mwe Hill topology Iso Near/Far flux West Reactor East Reactor 351 m 465 m 115 mwe Flat topology 9

10 The detector design Muon Outer VETO: 7 m ν target: 80% dodecane + 20% PXE + 0.1% Gd Volume for ν interaction 7m ν e 511 kev p n 511 kev e + Gd Σγ ~ 8 MeV γ catcher: 80% dodecane + 20% PXE Extra volume for ν interaction Acrylic vessels «hardware» definition of fiducial volume Non scintillating buffer: same liquid Isolate PMTs from target area Muon Inner VETO: scintillating oil Shielding: steel 17 cm: >7λ(γ). Improved background reduction PMT support structure: steel tank, optical insulation target/veto 10

11 The detectors Acrylic Gamma catcher vessel (Inner radius = 1,696m Inner H = 3,55 m t = 12mm) LS LS + 0,1%Gd Acrylic Target vessel (Inner radius =1,15m H = 2,474m t = 8mm) Muons VETO (shield) Inner radius = 3,471m Thickness = 200mm Stainless steel Buffer (Inner radius = 2,758m Inner H = 5,674m t = 3mm) 11

12 Liquids New DC Development: Solvent: 20% PXE (C 16 H 18 ) + 80% Dodecane (C 12 H 24 ) + PPO/Bis MSB. 1 g/l Gd(dpm) 3 tris (2,6 tetramethyl 3,5 heptanedione) Gd(III) Gd Scint. stability tested for 3 o C A SINGLE Batch LS for both detectors Target Solvant delivered GC Solvant: 4 % PXE 46% Dod. 50% Oil 100 Kg Gd compound delivered Buffer Oil Mixing Gd in August Sept 3 iso tanks ready for transportation, storage & filling MPIK new building for LS storage, mixing and purification 12

13 ν e Detector Parts Outer veto: Panels of strips of coextruded plastic scintillator with wavelength shifting fibre. Prototype constructed and two modules mass production of modules about to start. Acrylic vessels: Target : 8 mm, γ catcher : 12 mm R&D & Design completed customized acrylic batch 3 target vessels produced 2 are identical. Electronics & DAQ: L1 trigger board ready F ADC CAEN V1721 (500MHz & 8 bits) ordered 10 Hamamatsu tubes x 390 ~15 % coverage of inner det. Goal σ(e)/e~7 1 MeV Delivered, tested and installed. Acrylic vessels instalation: Integration tools ready and located in front of the far lab. 13

14 Far and Near Site Status Liquid Storage Building Tunnel entrance Neutrino Buffer PMT installation finished mid June. Laboratory Tunnel: 200 m Acrylic vessels installation in the end of July. Far lab: Tunnel : 200 New ventilation, doors, safety, Liquid storage building Being upgraded First liquids in fall (Veto/Buffer) Neutrino laboratory: 1 km baseline (14000 y 1 ) 300 m.w.e., µ Rate: ~20 Hz Fire security, Pit refubrished Steel tank installed 2008 Chooz A Power Plant Being dismantled J. Maricic, Drexel U Lab cleaned and painted(dec 2008) Muon Veto PMTs installed (February 2009) Buffer Vessel installed (April 2009) Thermalization system installed (April 2009) Buffer PMT installation (June2009) Acrylic tanks, filling liquids, electronics Neutrinos are close! Near lab: EDF committed to digging the near lab (November 2008) 14

15 Detector Signal Toward Small Systematic Errors Chooz had a 1.6% absolute detector systematic uncertainty, the best to date. Total uncertainty 2.7% Bugey is the only experiment that has tried to build identical detectors. Result was 2.0% relative error. 5.0% total. Simulation Target γ-catcher Double Chooz goal is 0.6% relative uncertainty and 0.5% total. Calibration: Target fish line & articulated arm γ catcher and buffer guide tubes Embedded LEDs Detailed geometry and optics Detector uniformity

16 Sensitivity (Limit) Timeline Δm 2 atm = ev 2 (20% uncertainty) σ sys =2.5% σ sys =0.6% Excluded by CHOOZ Efficiencies included 1% bin bin uncorrelated error on background subtraction. Syst. 1Det = CHOOZ Far detector (1km) alone Both detectors 1 km & 400 m years Systematics 2Det: σ abs = 2.0% σ rel = 0.6% σ scl = 0.5% σ shp = 2.0% σ Δm2 = 20% 16

17 Double Chooz Summary Double Chooz Far integration Started in May Far Detector construction & integration 2010 Start of phase I : Far 1 km detector alone sin 2 (2θ 13 ) < 0.06 after 1,5 year (90% C.L.) if no oscil Near Lab Escavation & Near Detector Integration Start of phase II : Both near and far detectors sin 2 (2θ 13 ) < 0.03 after 3 years (90% C.L.) if no oscil. Discovery potential Hints of θ 13 > 0 from global neutrino data analysis sin 2 θ 13 = 0.02 ±0.01 (sin 2 2θ 13 = 0.078) 1 year G. Fogli et al.,