The nu-e-bar electron elastic scattering cross-section was measured with a
CsI(Tl) scintillating crystal detector array with a total mass of 187 kg at the
Kuo-Sheng Nuclear Power Station. The detectors were exposed to a reactor
nu-e-bar flux of 6.4 X 10^{12} cm^{-2}s^{-1} originated from a core with 2.9 GW
thermal power. Using 29882/7369 kg-days of Reactor ON/OFF data, the Standard
Model (SM) of electroweak interaction was probed at the 4-momentum transfer
range of Q^2 ~ 3 X 10^{-6} GeV^2. A cross-section ratio of R_{expt} = [1.08 +-
0.21(stat) +- 0.16(sys)] X R_{SM} was measured. Constraints on the electroweak
parameters (g_V,g_A) were placed, corresponding to a weak mixing angle
measurement of $\s2tw$ = [0.251 +- 0.031(stat) +- 0.024(sys)]. Destructive
interference in the SM nu-e-bar+e processes was verified. Bounds on neutrino
anomalous electromagnetic properties (neutrino magnetic moment and neutrino
charge radius), non-standard neutrino interactions, upparticle physics and
non-commutative physics were placed. We summarize the experimental details and
results, and discuss projected sensitivities with realistic and feasible
hardware upgrades.Comment: 4 pages, 4 figures, 2 tables ; To appear in Proceedings of TAUP-2011
  Conferenc

Bilmis, Selcuk

Deniz, Muhammed

Wong, Henry T.

Journal of Physics : Conference Series

English

arXiv

Muhammed Deniz

Secluk Bilmis

Henry T Wong

null null

Crossref

Journal of Physics Conference Series

Final results of ν̄<sub>e</sub>— e scattering cross-section measurements and constraints on new physics

The (nu) over bar (e) - e elastic scattering cross-section was measured with a CsI(Tl) scintillating crystal detector array with a total mass of 187 kg at the Kuo-Sheng Nuclear Power Station. The detectors were exposed to a reactor (nu) over bar (e) flux of 6.4 x 10(12) cm(-2)s(-1) originated from a core with 2.9 GW thermal power. Using 29882/7369 kg-days of Reactor ON/OFF data, the Standard Model (SM) of electroweak interaction was probed at the 4-momentum transfer range of Q(2) similar to 3 x 10(-6) GeV2. A cross-section ratio of R-expt = [1.08 + 0.21 (stat) + 0.16 (sys)] x R-SM was measured. Constraints on the electroweak parameters (g(V), g(A)) were placed, corresponding to a weak mixing angle measurement of sin(2)theta(W) = 0.251 +/- 0.031 (stat) +/- 0.024 (sys). Destructive interference in the SM (nu) over bar (e)-e processes was verified. Bounds on neutrino anomalous electromagnetic properties (neutrino magnetic moment and neutrino charge radius), as well as non-standard neutrino interactions were placed. We summarize the experimental details and results, and discuss projected sensitivities with realistic and feasible hardware upgrades

Bilmiş, Selçuk

Dokuz Eylul University Research Information System

Final results of (nu)over-bar(e) - e scattering cross-section measurements and constraints on new physics

Wong, Henry T

OpenMETU (Middle East Technical University)

Journal of Physics: Conference SeriesOPEN ACCESSFinal results of νē — e scattering cross-sectionmeasurements and constraints on new physicsTo cite this article: Muhammed Deniz et al 2012 J. Phys.: Conf. Ser. 375 042044 View the article online for updates and enhancements.Related contentMeasurement of neutrino-electronscattering cross section and the EWparameters at the Kuo-Sheng reactorneutrino laboratoryM Deniz, H T Wong, S T Lin et al.-Status of neutrino-quark NSI parametersFrancisco J Escrihuela-Antineutrino studies with Borexino detectorOleg Smirnov and the Borexinocollaboration-Recent citationsShort baseline reactor ¯e scatteringexperiments and nonstandard neutrinointeractions at source and detectorAmir N. Khan et al-Precision ¯e -electron scatteringmeasurements with IsoDAR to search fornew physicsJ. M. Conrad et al-Cyclotrons as Drivers for PrecisionNeutrino MeasurementsA. Adelmann et al-This content was downloaded from IP address 144.122.201.61 on 25/07/2020 at 00:52Final results of ν̄e−escatteringcross-sectionmeasurements and constraints on new physicsMuhammed Deniza,b,c, Secluk Bilmisb,c and Henry T. Wong c(on behalf of the TEXONO Collaboration)a Department of Physics, Karadeniz Technical University, Trabzon 61080, Turkey.b Department of Physics, Middle East Technical University, Ankara 06531, Turkey.c Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.E-mail: htwong@phys.sinica.edu.twAbstract.The ν̄e−e elasticscattering cross-section was measured with a CsI(Tl) scintillating crystal detectorarray with a total mass of 187 kg at the Kuo-Sheng Nuclear Power Station. The detectorswere exposed to a reactor̄νe flux of 6.4×1012 cm−2s−1 originated from a core with 2.9 GWthermal power. Using 29882/7369 kg-days of Reactor ON/OFF data, the Standard Model (SM) ofelectroweak interaction was probed at the 4-momentum transfer range of Q2 ∼ 3×10−6 GeV2. Across-section ratio of Rexpt = [1.08±0.21(stat)±0.16 (sys)]×RSM was measured. Constraints on theelectroweak parameters(gV ,gA) were placed, corresponding to a weak mixing angle measurement ofsin2θW = 0.251±0.031(stat)±0.024(sys). Destructive interference in the SM̄νe-e processes wasverified. Bounds on neutrino anomalous electromagnetic properties (neutrino magnetic moment andneutrino charge radius), as well as non-standard neutrino interactions were placed. We summarize theexperimental details and results, and discuss projected sensitivities with realistic and feasible hardwareupgrades.Neutrino-electron scattering is pure leptonic process which is exactly evaluated with electroweaktheory. Cross-section measurement ofν̄e−e scatteringwith reactor neutrinos [1] provides a new windowto study the Standard Model (SM) electroweak parameters as well as anomalous neutrino electromagneticproperties such as charge radius and magnetic moments in a different kinematics regime from that ataccelerator. In addition, new physics beyond SM such as Non-Standard neutrinos interaction (NSI) andUnparticle Physics (UP) can be probed [2]. Theν̄e−e scatteringcross-section in the laboratory frameis:[dσdT(ν̄ee)]SM=G2Fme2π· [ (gV −gA)2+(gV +gA +2)2(1− TEν)2−(gV−gA)(gV +gA+2)meTE2ν], (1)whereGF is the Fermi constant, T is the kinetic energy of the recoil electron,Eν is the incident neutrinoenergy,me is mass of the electron andgV , gA are, respectively, the vector and axial-vector couplingconstants. The SM assignments to the coupling constants are:gV =−12 +2sin2 θW andgA =−12, wheresin2θW is the weak mixing angle. Interactions ofν̄e−e andν−earetwo of the few SM processes whichproceed via charged- and neutral-currentsand their interference, such that the event rates (R) can beexpressed by its components as:Rexpt = RCC+RNC+η ·RInt.A model-independent formulation of NSI is to characterizeν − e scatteringsas four-Fermiinteractions with new couplingsεePαβ which describe the coupling strength with respect toGF . The12th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2011) IOP PublishingJournal of Physics: Conference Series 375 (2012) 042044 doi:10.1088/1742-6596/375/4/042044Published under licence by IOP Publishing Ltd 1helicity states are denoted by P (=L,R), and(α,β ) standfor the lepton flavor (e,µ or τ) for theincoming/outgoing neutrinos. The cases whereα = β andα 6= β correspondto Non-Universal (NU)and Flavor-Changing (FC) NSI, respectively. Theν̄e−e cross-sectionincluding both SM and NSI isgiven by [3]:[dσdT]SM+NSI=2G2Fmeπ· [(g̃2R+ ∑α 6=e|εeRαe|2)+((g̃L +1)2 + ∑α 6=e|εeLαe|2)(1− TEν)2−(g̃R(g̃L +1)+ ∑α 6=e|εeRαe||εeLαe|)meTE2ν] , (2)whereg̃L = gL + εeLee and g̃R = gR+ εeRee , defined in terms of the chiral couplings:gL = 12(gV + gA) =−12 +sin2θW andgR = 12(gV −gA) = sin2θW.The measurement of̄νe−e elasticscattering atQ2 ∼ MeV2 was performed by the TEXONOCollaboration at the Kuo-Sheng Reactor Neutrino Laboratory in Taiwan. The experimental details weredocumented in Refs. [1, 4]. The CsI(Tl) target crystals were configured as a 12×9 array inside a shieldingstructure with∼50 tons of materials enclosed by an active cosmic-ray scintillator veto (CRV) system.Each single crystal module has a hexagonal-shaped cross-section with 2 cm side, 40 cm length andmodular mass of 1.87 kg. The detector consisted of 100 crystals giving a total mass of 187 kg. Thelight output was read out at both ends of the crystal by photomultipliers (PMTs) with low-activity glassof 29 mm diameter. The PMT signals were recorded by 20 MHz Flash Analog-to-Digital-Converters(FADCs) running on a VME-based data acquisition system. The sum of the two PMT signals gives theenergy of the event, while their difference provides information on the longitudinal “Z” position. Anenergy resolution of 4% and a Z-resolution of<1 cm RMS at 660 keV as well as excellentα/γ eventidentification by pulse shape discrimination (PSD) were demonstrated.10-410-310-210-111010 210 310 40 1000 2000 3000 4000 5000 6000 7000 8000Energy (keV)Rexpt(day-1kg-1[10 keV]-1)Raw DataCRVMHVPSDZ-Pos Cut137Cs40K208Tl10-410-310-210-13 5 7 9 11 13 15Energy (MeV)Rexpt(day-1kg-1[100 keV]-1).... CRV-Tag All Vetos63CuFigure 1.The measured energy spectra at variousstages of the analysis showing the effects ofsuccessive selection cuts.10-410-310-210-113 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5Energy (MeV)Event Rate (day-1 kg-1  MeV-1)H1 (CRV)  Data●❘H1 (CRV; µ) ❏208Tl Cascade ∆H1 (CRV; µ)⁄  T = Eγ ▼ T < EγIntrinsic 208TlSM   (νe - e)−Figure 2. Measured H1 spectrum and thedifferent evaluated background channels. The SMν̄e−econtributions are overlaid.Neutrino-induced candidate “single-hit (H1)” events were selected through the event-by-eventsuppression in the various background channels: (a) cosmic-ray induced events by CRV, (b)γ-inducedanti-Comptonevents by multiplicity veto (MHV), (c) accidental andα- events by PSD, and (c) external12th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2011) IOP PublishingJournal of Physics: Conference Series 375 (2012) 042044 doi:10.1088/1742-6596/375/4/0420442backgroundby longitudinal Z-position cut. Residual H1 background channels at the relevant 3−8 MeVrange are depicted in Figure 2, where the dominant components include: (i) cosmic-ray induced eventswhere CRV are missing; (ii) ambient high energyγ-rays following neutron capture of63Cu; and (iii)cascadeγ-rays from 208Tl. Their contributions were evaluated fromin situ measurement of CRVinefficiencies, multi-hit samples and the208Tl-2614 keV lines, coupled with simulation studies. andthe results provide the second background measurement. The combined background (BKG) werestatistically subtracted from the H1 spectra.A total of 29882/7369 kg-day of Reactor ON/OFF data was recorded. TheOFF−BKG spectrumis consistent with zero showing the background modeling and subtraction is valid. The combinedON−BKG residual spectrum is displayed in Figure 3, from which various electroweak parameterswere derived. The excess in the residual spectrum corresponds to∼414 neutrino-induced events,and an event-rate relative to that of SM at a ratio ofξ ≡ Rexpt/RSM = [1.08± 0.21(stat)± 0.16(sys)]which implies sin2θW = 0.251± 0.031(stat)± 0.024(sys). The allowed region in thegV − gA planeis depicted in Figure 4. The accuracy improves over previous reactorν̄e−e experiments [1] as wellas that in accelerator-basedνe−e scatteringexperiments [5]. The measured interference parameter ofη =−0.92±0.30(stat)±0.24(sys)verifies the SM prediction of destructive interference (ηSM =−1).-0.005-0.002500.00250.0050.00750.010.01250.0150.01750.023 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8Energy (MeV)Rexpt (day-1  kg-1 MeV-1)SMBest-FitFigure 3. The combined ON-BKG residualspectrum together with those of SM and best-fitresults.-1 -0.8 -0.6 -0.4 -0.2 -0 0.2 0.4 0.6-1-0.8-0.6-0.4-0.2-00.20.4gVgATEXONO(This Work)LSND0 0.5sin2θWFigure 4. The 1σ allowed region in gV −gA space, and in the sin2θW axis, for bothν̄e−e (TEXONO)andνe−e (LSND) scatteringexperiments.Existence of neutrino magnetic moment (µν̄e) would contribute an additional term to the cross-sectionof Eq. 1: (dσdT)µν=πα2emµ2νm2e[1−Te/EνTe], (3)whereαem is the fine structure constant. From a best-fit analysis, a limit ofµν̄e < 2.2×10−10× µB at90% confidence level (CL) was derived. A finite neutrino charge radius〈r2ν̄e〉 would lead to radiativecorrections which modify the electroweak parameters bygV →−12 + 2sin2θW +(2√2παem/3GF)〈r2ν̄e〉and sin2θW → sin2θW +(√2παem/3GF)〈r2ν̄e〉. The allowed range at 90% CL is−2.1×10−32 < 〈r2ν̄e〉<3.3×10−32. New constraints on NSI and UP couplings were also derived [2], as displayed in Table 1 forthose of NSI.12th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2011) IOP PublishingJournal of Physics: Conference Series 375 (2012) 042044 doi:10.1088/1742-6596/375/4/0420443Table 1.Constraints at 90% CL on the NSI couplings. The projected sensitivities correspond to improvedfeatures listed in Table 2.NSI Measurement Bounds ProjectedParameters Best-Fit±stat.±sys χ2/dof at 90% C.L. SensitivitiesNU { εeLee εeLee = 0.03±0.26±0.17 8.9/9 −1.53< εeLee < 0.38 ±0.015εeRee εeRee = 0.02±0.04±0.02 8.7/9 −0.07< εeRee < 0.08 ±0.002FC{ εeLeµ ,εeLeτ εeLeµ2(εeLeτ2) = 0.05±0.27±0.24 8.9/9 |εeLeµ |(|εeLeτ |) < 0.84 ±0.052εeReµ ,εeReτ εeReµ2(εeReτ2) = 0.008±0.015±0.012 8.7/9 |εeReµ |(|εeReτ |) < 0.19 ±0.007Table 2. Projected statistical sensitivities onξ and sin2θW under various realistically achievableimprovement to the experiment.Improvement ∆stat(ξ ) ∆stat[sin2θW]This Work 0.21 0.031Improved Feature:A. ×30 DataStrength 0.038 0.0057B. Background ReductionB1: >99% Cosmic-Ray Efficiency 0.12 0.018B2: × 110 Reductionin Ambient & 208Tl γ ’s 0.16 0.024∗ With Both B1+B2 0.05 0.007All Features A+B1+B2 Combined 0.009 0.0013The sensitivities can be further enhanced in future experiments. As illustrations, the projectedimprovement under various realistically achievable assumptions are summarized in Table 2.Electromagnetic calorimeters using CsI(Tl) with tens of tons of mass have been constructed, such thatthe target mass is easily expandable. As shown in Figure 2, the dominant background above 3 MeVwere all external to the target scintillator. Accordingly, they will be attenuated effectively through self-shielding in a target with bigger mass. The incorporated features listed in Table 2 correspond to 30times increase in data strength (for instance, with 1 ton fiducial mass and 1000 days data taking) and×1/10 suppression in background. The statistical accuracies can be improved to 0.8% and 0.12% forξand sin2θW, respectively. Systematic uncertainties originate mainly from the evaluation of the reactorneutrino spectra. This can be overcome by a simultaneous measurement of theν̄e spectravia the maturedinverse beta-decay processν̄e+ p→ n+e+ with, for instance, large liquid scintillator detectors.References[1] Deniz M et al. 2010Phys. Rev. D81072001, and references therein.[2] Deniz M et al. 2010Phys. Rev. D82033004, and references therein.[3] Barranco J et al. 2006Phys. Rev. D73113001; Barranco J et al. 2008Phys. Rev. D77093014.[4] Wong H T et al. 2000Astroparticle Phys.14 141; Li H B et al. 2001Nucl. Instrum. and Meth. A45993; Lai W P et al.2001Nucl. Instrum. and Meth. A465550; Liu Y et al. 2002Nucl. Instrum. and Meth. A482125; Zhu Y F et al., 2006Nucl. Instr. and Meth. A557, 490; Wong H T et al., 2007Phys. Rev. D75012001.[5] Allen R C et. al. 1993Phys. Rev. D4711; Aurbach L B et. al. 2001 Phys. Rev. D63112001.12th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2011) IOP PublishingJournal of Physics: Conference Series 375 (2012) 042044 doi:10.1088/1742-6596/375/4/0420444

Final results of V̄e - e scattering cross-section measurements and constraints on new physics

https://avesis.deu.edu.tr/publication/details/8233c6c2-ad57-4490-b0ff-f30eb3d003cd/oai