Searching for sterile neutrinos - PowerPoint Presentation

1. Searching for sterile neutrinoswith reactor experimentsJonathan Gaffiot, Ph.D.CEA Saclay: IRFU – Service de Physique NucléaireNucifer project - STEREO project09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's1

2. Reactor Antineutrino Anomaly09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's2

3. Neutrino spectraRevised conversion of spectra from e- measured @ ILL in 1980s flux: 235U +3.7%, 239Pu +4.2%, 241Pu +4.7%, 238U +9.8%Well controlled shape by measured e- spectra1.8% norm uncertainty due to neutron flux normalization @ ILL 09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's3Uranium 235

4. Reactor Antineutrino Anomaly19 measurements @L<100 m3 corrections to cross-section per fission :New spectra: Neutron lifetime decrease: Off-equilibrium correction: Best fit: 0.927 ± 0.023 (3 σ)At least 3 possibilities:Wrong spectra predictionExperimental biasNew Physics ! 09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's4

5. 4th neutrino hypothesisDisparition of neutrinos: new oscillation ?09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's5G. Mention et al., Phys. Rev. D 83, 073006 (2011)Atmospheric oscillationSolaroscillationNew oscillation to sterile n?

6. Reactor norm onlyReactor norm + shape (Bugey3 15m/40m)Reactor norm + reactor shape + galliumAnomaly contours09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's6

7. Detector specifications and challenges2 conditions to observe oscillations:Localization: compact coreFirst oscillation max: close to the reactor coreWith 0.1-1 eV², we need: 1-10 m and 0.1-1 mSmall (research) core and vertex localizating detectorCloseness with reactor and consequently surfaceChallenging measurement:High muon induced correlated background (low overburden)High reactor induced accidental background (gamma, thermal neutron) 09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's7

8. ON going projectSNuciferDANSS09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's8

9. Nucifer experimentOsiris research reactorAt Saclay, France70 MW, 20% Compact: 61x61x63 cm3 Detector designed for reactor monitoring studies850 kg Gd-loaded liquid scintillator400 neutrinos expected / dayBut oscillation detection abilities:Short baseline: only 7 m (center to center)Target: h = 70 cm, Φ = 1.2 m 09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's970 MWContact: T. Lasserre, D. Lhuillier, M. Fallot7 m

10. Commissioning and data takingData taking since april 2012Agreement from FrenchNational Security Agency (ASN)Remote control & automatic data transfertAccurate monitoring (Rates, gains, P, T…)Detector works well !09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's1060Co AmBe Reactor shutdown

11. Accidental backgroundNew south lead wallLead already acquiredInstallation at end of 201209/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's11Barycenters of the PMT’s chargesEastSouth3 m2 mpoolconcretecore3.35 m4 m1.2 mReactor OFF background on expectationprimary loopwater deactivation circuitPrimary loop water activationHigh energy g leakage from 16NUnexpected reactor ON background10 times higher than expectedPoint to south, but reactor at eastLead front wall is efficientExpected level at north 

12. Liquid scintillator upgradeLiquid scintillator shows unexpected short attenuation length 1mVertex dependent energy reconstruction: degradation of energy resolutionTime resolution not affected: preliminary studies of correlated background, veto muon efficiency (97 %)…New liquid based on Double-Chooz R&D to be provided this fall 09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's12

13. Contour after upgrades09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's13Expected spectrum distortion- Error stat only -300 days @ OsirisBest fit and  Upgrades planned to be finished early 2013With upgrades:If present, sterile hint possible MC detector responseRef spectra uncertaintyS/B=1.5= 2% 

14. DANSS experimentKalinin NPP #4 reactor3 GWth VVER (Russian PWR), extended coreSegmented "XY" plastic scintillator:Installation March 2013 (next OFF period)Under the reactor ( 50 m.w.e.)Movable lifting platform: 9.7 < L < 12.2 m1 m3 and / dayNumerous tests with "DANSSino":1/25th of final detectorDifferent shieldings tests (Pb, Cu, Cd…)Main background: -induced fast neutronEfficiency & resolution in agreement with MCIndication of signal / background > 1First results next year 09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's14Contact: V. Egorov

15. NEW DEDICATED PRojectsSCRAAMSTEREONEUTRINO-4POSEIDON09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's15

16. SCRAAM project09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's16Contact: N. BowdenSpectral distortion @SONGS (24m), DE/E=10% @ 1MeV sin2(2q) =0.165, Dm2 =2.4 eV2 Rapidly probe the RAA best fitAdapt existing designs and technologyBut requires overburden so limits sitesSONGS PWR site @ 24 m:Extended coreHigh statictics, cross check with Bugey-3Rapid exclusion of low Research reactor sites @ 10-15 m:Favorable cycles, pure , high Advanced Test Reactor (ATR, Idaho), 150 MWHigh Flux Isotope Reactor (HFIR, Oak Ridge), 80 MWCurrent evaluation of favorablereactor sitesGeometry, overburden, flux 

17. STEREO projectFrench and German projectILL research reactor (Grenoble):57 MW, highly enriched UCompact: h = 80 cm, Φ = 40 cmDedicated detector:5 segments: L and E oscillationActive outer layer: high efficiency + vetoMuon flux attenuation = 4,thick CH2 and Pb walls (70 t)09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's1740 cm36 cmTarget:Gd-doped liquid scintillator5 mContact: D. LhuillierSite being discussed with ILL

18. A phase shift of the oscillation is expected, no input from reactor.Unambiguous signature of neutrino oscillationSTEREO contour and phase shift09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's18Best fit, shape + norm, 300 daysMC detector responseRef spectra uncertaintyS/B=1.5= 2%= 3% 

19. NEUTRINO-4 experimentSM-3 reactor in Dimitrovgrad (Russia):100 MW compact core (35x42x42 cm3)2 detector geometries currently studied:24 sections 1.4x1.0x1.0 m3 5 sections moveable at 6-12 mPreparation at WWR-M reactor in GatchinaFuture realization at SM-309/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's19detectorcore5 mWWR-M reactor, 18 MWShielding studiesSM-3 reactor24 sections5 sectionsat SM-3,95% C.L.Contact: A. Serebrov

20. POSEIDON – POsition SEnsItive Detector Of Neutrino09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's20100 MW research Reactor PIK being built in Gatchina, (2014)Small core: h=50 cm, d=39 cmDetector can be placed at 5-8 m Gd loaded liquid scintillator detector: 2.1x1.3x1.3 m3 Region of sensitivity:δm2 = (0.3 - 6) eV2 sin2(2q)≥ 0.01 LAB+PPO+Gd 15 cmVeto+anti51164 6” PMTsEnergy and spatial resolution should allow to observe the oscillation curves for different Eν Contact: A. Derbin

21. ConclusionsCommunity moving forward to test the light sterile neutrino hypothesis: white paper http://cnp.phys.vt.edu/white_paper/ or arxiv:1204.5379Current experiments mainly designed for non-proliferationNucifer, DANSSNew generation of dedicated experiment (time scale 5 years)Search for norm free signature with L/E oscillationSegmented or vertex reconstructing detectors, high efficiency…Others studied neutrino projectBeta decay sources, accelerators, decay at rest… 09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's21

22. Back-up09/15/201222- Jonathan Gaffiot - Reactor experiments to test sterile nu's

23. Shape only data09/15/201223Bugey3 comparison 40m/15m:ILL pattern (not statistically significant)Bugey (1995)ILL (1981 – reanalysis 1995)- Jonathan Gaffiot - Reactor experiments to test sterile nu's

24. Nucifer Intallation09/15/201224Lead shieldingCH2 shieldingMuon vetoLead front wallShielding supportFilling- Jonathan Gaffiot - Reactor experiments to test sterile nu's

25. Photoelectron calibrationLED + fiber + diffuser single photoelectron signalAutomatic fit of spe (16 ch) pedestal + gainOthers LED for stability, linearity09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's25Pedestal +- 0.5%Gain +- 2.5 %Measured each run or 10 runs (need statistic)

26. Sources simulation09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's26

27. Pulse Shape Discrimination in Nucifer09/15/201227PXE 50% - Dodecane 50% - Jonathan Gaffiot - Reactor experiments to test sterile nu's

28. Reactor Spectrum Calculation Sensitivity to plutonium content09/15/201228a235Ua239Pu- Jonathan Gaffiot - Reactor experiments to test sterile nu's

29. Neutrinos & non proliferationArrêt réacteurrechargement d’1/3 du combustible1m3 detector 25 m away from a 3 GW reactor  2000 interactions/dA neutrino working group was created last year by the AIEAReactor operating at constant powerP (GW)At fixed power the n rate decreases as Pu accumulates in the core09/15/201229- Jonathan Gaffiot - Reactor experiments to test sterile nu's

30. Passive Shielding30LeadIron*Cosmic Ray Interactions in Shielding Materials, E. Aguayo et al, PNNL-20693 Study of cosmic rays attenuation at surface performed for the MAJORANA collaboration*Favor thick light materials.Concrete09/15/2012- Jonathan Gaffiot - Reactor experiments to test sterile nu's

31. STEREO shape only contours09/15/201231Background shape uncertainty- Jonathan Gaffiot - Reactor experiments to test sterile nu's

32. DANSS contour from Saclay teamCore size prevents effective oscillation detection09/15/201232Shape only analysis- Jonathan Gaffiot - Reactor experiments to test sterile nu's

33. Mean cross-section per fission09/15/201233 ν-flux: 235U +3.7%, 239Pu +4.2%, 241Pu +4.7%, 238U +9.8% (σfpred ) Neutron lifetime decrease by a few % (σfpred ) Off-equilibrium corrections (σfpred )+4.7%+5.0%+9.7%+5.2%new/oldUpdated cross-sections per fission:- Jonathan Gaffiot - Reactor experiments to test sterile nu's

34. n spectrum emitted by a reactor 09/15/201234=S all fission products- Jonathan Gaffiot - Reactor experiments to test sterile nu's

35. Accurate prediction of reactor n spectraThermal powerδPth ~ 0.5% at commercial reactorsFraction of fissions from isotope k, δak=few %E released per fissions of isotope k, δEk≈0.3%ν spectrum per fissionDominant source of uncertaintyReactor dataNuclear databasesReactor evolution codes09/15/201235- Jonathan Gaffiot - Reactor experiments to test sterile nu's

36. Reactor Spectrum Calculation09/15/201236Detected spectrum / fissionCross section / fission:- Jonathan Gaffiot - Reactor experiments to test sterile nu's

37. The guts of Sk(E)Sum of all fission products’ activitiesSum of all β-branches of each fission productTheory of β-decay09/15/201237- Jonathan Gaffiot - Reactor experiments to test sterile nu's

38. Theory of b-decay09/15/201238W = total energyW0 = end-pointp = momentumZ = Nuclear chargeFermi theory:Corrections: Fermi functionPhase spaceShape factor of forbidden Finite size of nuclear electric chargeFinite size distrib. of decaying neutronScreening of Atomic e-QED radiative correctionWeak magnetismn branch obtained by replacing: WW0-W, GbGn- Jonathan Gaffiot - Reactor experiments to test sterile nu's

39. Corrections to Fermi theory09/15/201239Example of a single branch with Z=46A=117E0=10 MeVTotal fission spectra is a sum over a quasi continuous end-point distribution  +/- cancellation at low E, adds up at high E.Can’t neglect this when looking for oscillation patterns or accurate total rate.P. Huberb spectrum correctionsn spectrum corrections- Jonathan Gaffiot - Reactor experiments to test sterile nu's

40. Neutron Life time09/15/201240Continuous decrease of tn in the history of measurements Latest average including MAMBO II result: tn = 881.5 s- Jonathan Gaffiot - Reactor experiments to test sterile nu's

41. ILL data: reference b- Spectra09/15/201241Target foil (235U, 239Pu, 241Pu)in thermal n fluxMagnetic BILLspectrometerILL research reactor(Grenoble, France)e-Emitted b spectra per fissionA. A. Hahn, K. Schreckenbach et al., Phys. Let. B218,365 (1989)+ refs thereinAccurate e- measurements @ ILL in Grenoble (1978-89)W. Mampe et al., Nucl. Instrum. Meth. 154 (1978).- Jonathan Gaffiot - Reactor experiments to test sterile nu's

42. Normalization of ILL data09/15/201242207Pb(n, g)208Pb115In(n, g)116mIn113Cd(n,g)114Cd Dominant systematic error : 1.8 % (1 s)Absolute calibration via internal conversion electron lines of known partial cross section per neutron captureCorrelated across all energy bins of all isotopes + directly propagates into the converted antineutrino spectra.&: absolute normalization: relative normalization- Jonathan Gaffiot - Reactor experiments to test sterile nu's

43. e- n conversion09/15/201243b-branch levelFission product level Lot of relevant quantities: Z, A, End-points, Jp, nuclear matrix elements, branching ratios, fission yields, life time… but scarce data as E0 increases Exact conversion requires complete knowledge from fission yield down to b- transition between parent ground (or isomeric)-state and daughter states- Jonathan Gaffiot - Reactor experiments to test sterile nu's

44. Conversion of reference e- spectra441- Fit total e- spectrum with a sum of 30 effective b branches determined by iterative method (instead of ~10,000+ real branches) 2- Convert each effective e- branches to ν branches3- Sum all converted ν branches to get total ν spectrumK. Schreckenbach et al., Phys. Lett. 99B, 251 (1981).A.A. Hahn et al., Phys. Lett. 218B, 365 (1989).- Jonathan Gaffiot - Reactor experiments to test sterile nu's09/15/2012

45. ILL n spectra09/15/201245Emitted spectrum / fissionConverted energy spectrum S(E) for 235U, 239Pu and 241Pu.Reference spectra over the last 25 yearsAb initio calculation for 238U spectrum + new data from FRM2(Nils Haag et al.)- Jonathan Gaffiot - Reactor experiments to test sterile nu's

46. New Predictions of n Spectra09/15/201246Residuals to reference ILL data +3% normalization shift with respect to ILL ν spectrum Similar result for 235U and Pu isotopes, +9.8% for 238U because of more complete ab initio approach. Origin of the bias well identified:- Effective implementation of corrections to Fermi theory- Nuclear charge distribution of virtual branchesTh. Mueller et al, Phys. Rev. C83,054615 (2011)- Jonathan Gaffiot - Reactor experiments to test sterile nu's

47. Confirmed by Independent Work09/15/201247 Confirms global increase of predicted spectrum Fixes remaining oscillations of mixed-approach prediction Extra deviation at high energy from more complete correction to Fermi theory. ν-flux: 235U +3.7%, 239Pu +4.2%, 241Pu +4.7%New conv.New conv. with simple b-shapeMixed-approachILL inversionP. Huber, Phys. Rev. C84, 024617(2011)- Jonathan Gaffiot - Reactor experiments to test sterile nu's

48. Reanalysis of All Short Baseline experiments09/15/201248- Jonathan Gaffiot - Reactor experiments to test sterile nu's

49. 19 measurements @ L<100m09/15/201249BugeySavannah RiverRovnoGoesgenILLKrasnoyarskDifferent detector technics, different core compositions, different backgrounds, …- Jonathan Gaffiot - Reactor experiments to test sterile nu's

50. 19 measurements @ L<100m09/15/201250Variety of detection techniques, baselines, core compositions,…meas/pred- Jonathan Gaffiot - Reactor experiments to test sterile nu's

51. Correlation Matrix09/15/201251 Bugey-4 15m Rovno91 18m Bugey-3 15m Bugey-3 40m Bugey-3 92m Goesgen 38m Goesgen 45m Goesgen 65m ILL 9m Krasno 33m Krasno 92m Krasno 57m SRP I 18m SRP II 25m Rovno88 1I 18m Rovno88 2I 18 m Rovno88 1S 18m Rovno88 2S 25m Rovno88 3S 18m Global 2% correlated norm error of ILL β-spectra Block correlations come from identical detector, technology or n source3.03.03.93.05.05.05.15.014.15.06.56.07.66.09.56.05.14.15.14.120.34.14.14.13.73.73.83.76.96.96.96.97.87.27.87.27.27.2(in %)(correlation matrix on Ratios)- Jonathan Gaffiot - Reactor experiments to test sterile nu's

52. 238U b spectrum soon to be published09/15/201252 N. Haag Ph.D. thesis to be published by end of this year.Analysis of electron data is final, conversion to neutrino on progress.Anchor point of 235U measurement:- Background well understood. - Comparison to ILL spectrum cancels most uncertainties.N. Haag, K. Schrekenbach et al.New 238U data @ FRMII reactor, Munichn fluxNatural U foilbMWCPlastic Scintillator- Jonathan Gaffiot - Reactor experiments to test sterile nu's