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Academia Sinica Seminar Taipei, TAIWAN, 21 May 2010

Measurement of Neutrino-Electron Scattering with CsI(Tl) Scintillators at the Kuo-Sheng Neutrino Laboratory. Muhammed Deniz 1,2 1: IoP , Academia Sinica , Taiwan 2: METU, Ankara, Turkey On behalf of TEXONO Collaboration. Academia Sinica Seminar

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Academia Sinica Seminar Taipei, TAIWAN, 21 May 2010

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  1. Measurement of Neutrino-Electron Scattering with CsI(Tl) Scintillators at the Kuo-Sheng Neutrino Laboratory Muhammed Deniz1,2 1: IoP, Academia Sinica, Taiwan 2: METU, Ankara, Turkey On behalf of TEXONO Collaboration Academia Sinica Seminar Taipei, TAIWAN, 21 May 2010

  2. OUTLINE • Theory overview ne – e- Scattering – Motivation • Cross Section & EW Parameters – World Status • TEXONO Physics Program • TEXONO Experiment – CsI(Tl) Array • Event Selection & Data Analysis Outline • Background Understanding & Suppression • Analysis Results • Probing New Physics – NSI & UP with ne – e- • Summary 2/43 Measurement of Neutrino-Electron Scattering

  3. ne – e-Scattering Formalism e + e-e+ e- • A basic SM process with CC, NC & Interference • Not well-studied in reactor energy range ~ MeV 3/43 Measurement of Neutrino-Electron Scattering

  4. Neutrino-Electron Scattering Cross-Section e + e-e+ e- 4/43 Measurement of Neutrino-Electron Scattering

  5. Experiments Experiments LSND Savannah LAMPF Krasnoyarsk Rovno MUNU TEXONO World Status Characteristics of the previous antineutrino-e scatteringexperiments Target Fiducial Mass (kg) Thr. (MeV) Signal Events S / B Accuracy (ee) Plastic Scin. 15.9 1.5-4.5 458 0.18 29%* Fluorocarbon 103 3.2-5.2 …. 0.1 53% Si(Li) 37.5 0.6-2.0 41 0.008 49% CF4 gas 11.4 0.7-2.0 68 0.2 50% CsI(Tl) Scin. 187 3.0-8.0 414 ~ 0.03 25% Characteristics of the previous neutrino-e scattering Accelerator experiments Target Fiducial Mass Thr. (MeV) Signal Events Accuracy (ee) Liquid Scin. 167 tons 10-50 191 15% Plastic Scin. 15 tons 7-60 236 17.5% 5/43 Measurement of Neutrino-Electron Scattering

  6. sin2qW measurement in the World PDG 2008 “There is NO significant measurement at low energies especially with reactor anti-neutrino” ? 6/43 Measurement of Neutrino-Electron Scattering

  7. TEXONO Physics Program quality mass Detector requirements Observable Spectrum with typical reactor neutrino “beam” TEXONO Collaboration: Taiwan(AS,INER,KSNPS,NTU); China (IHEP,CIAE,THU,NKU,SCU,LNU);Turkey (METU);India (BHU) Program:Low Energy Neutrino & Astroparticle Physics Taiwan EXperiment On NeutrinO [3] [1] [2] [1]Magnetic Moment Search at~10 keV PRL 2003, PRD 2007 [2]Cross-Section and EW Parameters measurementat MeV range  PRD 2010 [3]ne N Coherent Scattering & WIMP Searchat sub keV range 7/43 Measurement of Neutrino-Electron Scattering

  8. TEXONO Physics Program on CsI(Tl) detector e + e-e+ e- • attempt a measurement of Standard Model  (ee-)  sin2w at MeV range Measurement :Recoil Energyofe- • properties are not fully understood intense -source Reactor : high flux of low energy (MeV range) electron anti-neutrinos. CsI(Tl) (200 kg) : • Region of Interest for e - e scattering Big uncertainties of modeling in the low energy part of reactor neutrino for SMs(nee)higher energies (T>3 MeV) 8/43 Measurement of Neutrino-Electron Scattering

  9. Kou-Sheng Reactor Power Plant KS NPS -II : 2 cores  2.9 GW KS  Lab: 28m from core #1 10 m below the surface 30 mweoverburden Total flux about 6.4x1012 cm-2s-1 9/43 Measurement of Neutrino-Electron Scattering

  10. Neutrino Laboratory Inner Target Volume & Shielding 10/43 Measurement of Neutrino-Electron Scattering

  11. CsI Scintillating Crystal Array Normal Event Pulse Alpha Event Pulse CsI(Tl) Detector 9x12 Array200 kg Experimental Approach; CsI(Tl) Crystal Scintillator Array: • proton free target (suppress ne-p background) • scale to  (tons) design possible • good energy resolution, alpha & gamma Pulse Shape Discrimination (PSD) • allows measure energy, position, multiplicity • more information for • background understanding & suppression • DAQ Threshold: 500 keV • Analysis Threshold: 3 MeV (less ambientbackground& reactor nespectra well known) • Data Volume: ~ 29883 kg-day / 7369 kg-day ON/OFF • Energy : Total Light Collection • s (E) ~ 10% FWHM @ E>660 keV • Z-position : The variation of Ratio • s (Z) ~ 1.3 cm @ E>660 keV 11/43 Measurement of Neutrino-Electron Scattering

  12. CsI(Tl) (200 kg) Connecting Board KS CsI(Tl) Experiment Configuration FADC Readout 16 ch., 20 MHz, 8 bit Multi-Disks Array (several Tb) 12/43 Measurement of Neutrino-Electron Scattering

  13. Dynamic Range of FADC Z = 0 cm QR Z =40 cm 208Tl 40K 137Cs QL Region of Interest for SM ee) Single Crystal QL vs QR (Raw Data) Goal:to reconstruct the missing part of the saturated pulse to get the charge and energy. Nucl. Instr. and Meth. A 511 (2003) 408-416. Unsaturated Saturated 13/43 Measurement of Neutrino-Electron Scattering

  14. Reactor OFF Data Analysis: Event Selection 14/43 Measurement of Neutrino-Electron Scattering

  15. A.Radioactive Contaminants • Decays of radioactive contaminants mainly232Th and238U decay chainproduce background in the region of interest. Estimate the abundance of 137Cs,238U and 232Th inside the detector. IDEA: By monitoring the timing and position information related β-α or α-α events can provide distinct signature to identify the decay process and the consistency of the isotopes involved. B.Environmental Backgrounds • Cosmic Ray muons, Products of cosmic ray muons, Spallation neutrons and High Energy g ‘s from such as 63Cu, 208Tl IDEA:multiple-hit analysis can give us very good understanding 208Tl, High Energy gand cosmicrelated background in the region of interest. • Cosmic & High Energy Gamma - By comparingcosmicandnon-cosmicmultiple-hit spectra. • Tl-208 - By examining multiple-hit spectra as well as simulation of Tl-208 decaychain energies to understand/suppress backgroundin the region of 3-4 MeV. Background Understanding 15/43 Measurement of Neutrino-Electron Scattering

  16. Intrinsic 137Cs Level Nucl. Instr. and Meth. A 557 (2006) 490-500. 31.3 kg-day of CsI(Tl) data was analysed. 137Cs contamination level in CsI was drived ==> (1.55 ± 0.02 ) X 10-17 g/g 16/43 Measurement of Neutrino-Electron Scattering

  17. T1/2 = (283 ± 37) ns. T1/2 = (163 ±8) ms α β α a a β T1/2 = (0.141± 0.006) s Intrinsic U and Th Contamination Level Data: The total of 40 crystals with data size of 1725 kg·day was analyzed. ii) 212Bi(b-,64%) → 212Po(a, 299ns) → 208Pb i) 214Bi(b-)→ 214Po(a,164ms) →210Pb Selection:b-pulse followed by a large a pulse Selection: 1st pulse is g(b) shaped & 2nd pulse a shaped 232Th abundance = 2.3 ± 0.1 x10-12 g/g 238U abundance = 0.82 ± 0.02 x10-12 g/g iii) 220Rn(a)→ 216Po(a, 0.15s) → 212Pb Selection:twoa events with time delay less than 1s 232Th abundance = 2.23 ± 0.06 x 10-12g/g 17/43 Measurement of Neutrino-Electron Scattering

  18. Intrinsic Radiopurity Measurementand Contamination Level 18/43 Measurement of Neutrino-Electron Scattering

  19. 208Tl beta with associated gammas energies deposit in one crystal. 232Th (decay chain) This is 11% of signal and can be negligible in our background level of ~ 0.4 cpdin 3 - 5 MeV Estimate the background due to Intrinsic 208Tl 3a, 3b BR 36% 0.4% 0.00134 19/43 Measurement of Neutrino-Electron Scattering

  20. Background Understanding: via Multiple Hit Analysis 2 HIT SPECTRUM 3-4 MeV 4-8 MeV 20/43 Measurement of Neutrino-Electron Scattering

  21. Etot = 2-3 MeV Etot = 3-4 MeV Etot = 1-2 MeV External Source(s) 511 keV 605 keV 2100 keV 796 keV 1173 keV 1332 keV Background Understanding viaMulti Hit • Co-60:1173.2keV 99.86% accompanied with 1332.5keV 99.98% • The background related to reactor. Mostly come from the dust. • Tl Pair Production:One escape peaks • (~ 2105 + 511 keV) Cs-134(n + 133Cs g134Cs) • 605 keV 97.6%; • 796keV 85.5% External Source(s) 510, 583 keV 2614 keV With the Q of beta decay at 2MeV Internal Source(s) 2614keV 99 % accompanied with 583 keV 85% 510.8 keV 23% 860 keV with 13% 860 keV • Cosmic induced neutrons can be captured by the target nuclei 133Cs. • Combination of Tl gammas can affect up to around 4 MeV 21/43 Measurement of Neutrino-Electron Scattering

  22. Ee-e+ Ee-e+ Ee-e+ Background Prediction via PAIR PRODUCTION 2 - HIT 3 - HIT q p q q p SH p 22/43 Measurement of Neutrino-Electron Scattering

  23. cosmic/non-cosmic ratio for 3-hit Pair production events Cosmic Inefficiency Tl-208 (3-4 MeV) 208Tlchain2-hitenergy spectra Simulation with angular correlation Environmental Background Understanding All crystals including 20+20 and 40 cm crystals data was analyzed. 23/43 Measurement of Neutrino-Electron Scattering

  24. Idea -- Use Multiple Crystal Hit (MH)spectra to predict Single Crystal Hit (SH) Background to the neutrino events Residual Background Understanding & Suppression • Background Sources :High Energy g& CosmicRays&208Tl 24/43 Measurement of Neutrino-Electron Scattering

  25. Background Understanding: Due to Tl-208 in 3-4 MeV Region 25/43 Measurement of Neutrino-Electron Scattering

  26. Tl-208 Induced and Cosmic SH BKG Estimation OFF-BKG SH  2614keVg  (583keVg) or  (510keVg) or  (860keVg) 26/43 Measurement of Neutrino-Electron Scattering

  27. Background Understanding & Suppression Combined BKG(SH)from three measurements: • Direct Reactor OFF(SH) spectra  Predicted BKG(SH) from OFF(MH)  Predicted BKG(SH) from ON(MH) = ON(SH) – BKG(SH) 27/43 Measurement of Neutrino-Electron Scattering

  28. Systematic Uncertainties Approach – Use non-n events for demonstration 208Tl Peak Events Stability BKG – Pred. (neutrino free region) ON-OFF Stability< ~0.5% • Random trigger events for DAQ & SelectionCuts • Stability ofTl-208(2614 keV) peak events Cosmic Induced BKG(SH) Prediction < ~1 % • Successfully Predict Cosmic BKG in NEUTRINO FREE REGION Tl-208 Induced BKG(SH) Prediction <~3% • Successfully Predict Tl-208 Induced BKG(SH) >3MeV atReactor OFF periods • Successfully Predict Tl-208 peak intensity for both ReactorON/OFFwith the same tools (MC) 208Tl (SH) Prediction 28/43 Measurement of Neutrino-Electron Scattering

  29. The Sources & Contribution of Systematic Uncertainties 29/43 Measurement of Neutrino-Electron Scattering

  30. Cross Section & Weak Mixing Angle Phys. Rev. D 81, 072001 (2010) ON-BKG A Better Sensitivity 30/43 Measurement of Neutrino-Electron Scattering

  31. ne-e- ne-e- World Status: Summary Table Experiment Energy (MeV) Events Cross-Section sin2qW [10.0 ± 1.5 ± 0.9] x Ene10-45cm2 0.249 ± 0.063 LAMPF [Liquid Scin.] 7 - 60 236 [10.1 ± 1.1 ± 1.0] x Ene10-45cm2 0.248 ± 0.051 LSND [Liquid Scin.] 10 - 50 191 [0.86 ± 0.25] x sV-A [1.70 ± 0.44] x sV-A 0.29 ± 0.05 Savannah-River [Plastic Scin.] 1.5 - 3.0 3.0 – 4.5 381 71 Savannah-River Re-analysed (PRD1989, Engel&Vogel) 1.5 – 3.0 3.0 – 4.5 N/A [1.35 ± 0.4] x sSM [2.0 ± 0.5] x sSM N/A Krasnoyarsk (Fluorocarbon) 3.15 – 5.18 N/A [4.5 ± 2.4] x 10-46 cm2/fission 0.22 ± 0.75 Rovno [Si(Li)] 0.6 – 2.0 41 [1.26 ± 0.62] x 10-44 cm2/fission N/A 1.07 ± 0.34 events day-1 N/A MUNU [CF4(gas)] 0.7 – 2.0 68 [1.08 ± 0.21 ± 0.16] x RSM 0.251 ± 0.031(stat) ± 0.024(sys) TEXONO [CsI(Tl) Scin.] 3 - 8 414 ± 80 ± 61 31/43 Measurement of Neutrino-Electron Scattering

  32. Neutrino-Electron Scattering Cross-Section e + e-e+ e- 32/43 Measurement of Neutrino-Electron Scattering

  33. Interference, Neutrino Magnetic Moment and Charge Radius Interference Term h= - 0.92 ± 0.30(stat) ± 0.24(sys) mn2 = [0.42 ±1.79(stat) ±1.49(sys)].mB2 at 90 % C. L. 33/43 Measurement of Neutrino-Electron Scattering

  34. NSI of Neutrino • n mass models all mechanisms carry modifications to the structure of the standard EW NC& CC • V-A Form, similar to the four Fermi • exchange of Higgs • Supersymmetric scalar bosons • New heavy gauge boson Z’ • There is a strict bound on derived from m 3edecay • The main parameters will be for FC NSI and for NU-NSI. 34/43 Measurement of Neutrino-Electron Scattering

  35. Observable spectrumwith typical reactor neutrino “beam” & Typical values of NSI parameters NSI of Neutrino • ne – e- scattering provide a sensitive tool to probe NSI CsI(Tl) 186 kg 35/43 Measurement of Neutrino-Electron Scattering

  36. Comparison of Bounds of NSI Parameters 36/43 Measurement of Neutrino-Electron Scattering

  37. Unparticles • The notion of unparticles is introduced by Howard Georgi . A scale invariant sector which decouples at a suffciently large energy scale exists. (Phys. Rev. Lett. 98, 221601 (2007) • The signatures of Unparticle Physics can also be observed by reactor neutrinos by searching the effects of virtual unparticle exchange between fermionic currents. • This interaction can be either exchange of Scalar Unparticles or Vector Unparticles. Exchange of Scalar Unparticles 2.Exchange of Vector Unparticles For the flavour changing case: i= 0(1): Unparticle scalar/vector field l0 (l1) :Scalar(Vector) unparticle couplings f : e, u, d a, b:denotes neutrino flavours d: Unparticle mass dimension L: Unparticle energy scale For the flavour conserving case 37/43 Measurement of Neutrino-Electron Scattering

  38. Unparticle Physics Unparticle physics is a speculative theory that conjectures matter that can not be explained in terms of particles, because its components are “scale invariant”, a property of fractals. “Scale invariance” is a feature of objects or laws that do not change if length scales (or energy scales) are multiplied by a common factor. A fractal is a rough or fragmented geometric shape that can be split into parts, each of which is (at least approximately) a reduced-size copy of the whole," a property called self-similarity. 38/43 Measurement of Neutrino-Electron Scattering

  39. a + e-UPb+ e- Unparticles ULB Ge L = 1 TeV 39/43 Measurement of Neutrino-Electron Scattering

  40. Unparticle – Exclusion Plots CsI(Tl) 186 kg This Talk PRD 2010 ULB Ge 1 kg MM Data Set PRD 2001, PRD 2007 ULE Ge 20 g WIMP data set PRD 2009 40/43 Measurement of Neutrino-Electron Scattering

  41. Scalar Unparticle – Preliminary Results LU= 1 TeV LU= 1 - 10 TeV Unparticle effects decreases as LU increases Results are improved over those from Borexino and MUNU experiments 41/43 Measurement of Neutrino-Electron Scattering

  42. Vector Unparticle – Preliminary Results L = 1 TeV L = 1 - 10 TeV 42/43 Measurement of Neutrino-Electron Scattering

  43. Summary • Detector: CsI(Tl) Scintillating Crystal Array (~ 200 kg) • Threshold: 3 MeV • Analysis Results: • s(ne – e-) with ~ 25% accuracy • Weak Mixing Angle with ~ 15% accuracy • Verify SM negative interference • mnsensitivity~ 10-10mB • neutrino charge radius sensitivity~ 10-32 cm2 • Probing new Physics :NSI and UP -- Preliminary • Current bounds are improved over those from the previous experiments 43/43 Measurement of Neutrino-Electron Scattering

  44. Thank YOU Measurement of Neutrino-Electron Scattering

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