WIXLIB

UCLEIDaya Bay(An Experimental Overview)EINN 2013PaphosNovember 2nd ‘13Alessandro Bravar

Neutrinos In the “Current” Standard ModelStandard Model :using 19 parameters the SMpredicts the interactions ofelectroweak and strong forces,the properties of 12 fermions,and 12 bosons carrying the forceneutrinos : 3 types (flavors) lefthanded only neutral fermions– interact only weakly all have equal (weak)interactions assumed massless in the SM

But Where They Are ?Neutrinos are naturally produced in the Sun, the atmosphere, earth, our bodies, They can be also “fabricated” in nuclear reactors or by accelerators,

Neutrino SourcesGlashow resonancene e nm mne e ne e

Neutrino Physics SituationEspecially since 1998, neutrino physics has made great progress– discovery of oscillation (nm disappearance) in atmospheric n by SK (1998)confirmation in accelerator nm beam by K2K (2004) / MINOS (2006)– ne disappearance ( nm/nt)established by solar neutrino measurements by SNO / SK (2002)confirmation in reactor n by KamLAND (2004)– ne appearance nm ne by T2K (2.5 s in 2011 and 7.5 s in 2013)q13 0 by DayaBay (2012)confirmed 3 flavor mixing picture of neutrinosSurprises ( Mysteries) are– neutrino has really finite (but small) mass:first evidence of deviations from Standard Model– neutrino has finite (but big) flavor mixing (unlike quarks)lepton flavor is violated

Neutrino Oscillation n oscillations are a quantum mechanical effect neutrino flavor eigenstates (e, m, t)are different from mass eigenstates (1, 2, 3)n U i 1, 2, 3ini propagation in time (& space) described by the free Hamiltonian neutrino oscillations: probability of observing a given n flavorwill vary with time (flavor changes to other flavor in flight) only occur when neutrinos have finite mass and mixnmtMu neutrinoTau neutrino

3 Flavor Mixing of NeutrinosFlavor eigenstatesnenmnt n e n 1 n m U P MNS n 2 n n t 3 m1Mass eigenstatesm2m3Pontecorvo-Maki-Nakagawa-Sakata Matrix (CKM matrix in lepton sector)q23 450 60SuperK (atm. n)K2K / MinosT2Kq13 9.10 0.60Daya BayRenoT2Kq12 33.60 1.00solar nKamLANDfuture solar n exp.6 independent parameters govern oscillationq12,q23,q13,dcp,Dm122,D m232,neutrinolessdouble betadecayDm132

Neutrinos Oscillations In Time Evolution(three flavor oscillations)nmneEnmνntn (t ) U i en (t 0) U i n ii2ne iEi tnimi2Ei p 2pi U i U i U i U i U i U i e2iPm enttt 0P n (t ) n (t 0)ne-i(Ei -E j ) ti j2 Dm2a22222 31 L 4C13 S13 S 23 sin1 2S13 ) 1 2 4 E Dm31 leading, q13 driven22Dm32LDm321 LDm21L 8C13 S12 S13 S 23 (C12C23 cos d S12 S13 S23 ) cossins inCPC4E4E4E222Dm32LDm31LDm21L2CPV 8C13 C12C23 S12 S13 S 23 sin d sinsinsin4E4E4E222222222 Dm21 L 4 S12 C13 (C12 C23 S12 S 23 S13 2C12C23 S12 S 23 S13 cos d ) sinsolar4E2Dm32LDm321 L2222 aL 8C13 S13 S23 (1 2 S13 )cossinmatter effect4E4E4E2

Two flavor Oscillation in Vacuum(to make it simple) cos qU sin qFor two flavors, n and n ,the mixing matrix reduced tosin q cos q then the oscillation probability P(n n ) is given by ( Ei E j )t P(n n ) sin 2q sin 2 mi2Making the approximation Ei p 2p22(and including the factors h and c)the oscillation probability becomes L [km]22 P(n n ) sin 2q sin 1.27Dm [eV ] E [GeV] 2maximum oscillation amplitude2L : distance ν- sourceE : ν-energy at t 0 (source)oscillationfrequency

Present Knowledgen3atmo.solarreactorn2ORn1dCP unkownwhich ? both ordering allowed by data0.14big difference w.r.t. CKM matrix

Today’s Questions In Neutrino Physics Mass hierarchywe do not know if the neutrino n1 (contains more ne) is the lightest one or not Long baseline accelerator neutrino experiments Is CP symmetry violated ?help solve origin of matter-antimatter asymmetry in universe (leptogenesis) Long baseline accelerator neutrino experiments Absolute neutrino mass Tritium beta decay spectrum neutrino-less double beta decay Existence of sterile neutrinos Neutrino is Dirac ? or Majorana ? neutrino-less double beta decayUnraveling full nature of neutrino could provide breakthroughto approach our goals in particle physics

How Do We Make an Oscillation Experiment1. measure n spectrum at near detector before oscillations2. make prediction at far detector assuming no oscillations expFD POSC RF / N obsNDs FD En ) eff ND #ev FD En ) POSC En ) #ev ND En ) RF / N s ND En ) eff FD3. compare measured n spectrum at far detector with predictions (2)deviations ? oscillationsdoes not cancel 4. extract oscillation parametersbecause different spectra !nm disappearancene disappearancesin 2 2q13 0.150 0.0390.034q 23 450 60 (90%C.L.)20.12Dm32 2.32 0.08 10 3 eV 2Dm2sinq

Why Neutrino Cross–Sections ?existing n scattering data ( 1 – 20 GeV) poorly understoodmainly (old) bubble chamber datalow statistics sampleslarge uncertainties on n fluxneed detailed understanding of nm and anti-nm cross sectionsn oscillationprecision neutrino oscillation measurementsall experiments use dense nuclear targets (CH, H20, Ar, Fe, ) additional complications whose impact needs to be understoodbackgrounds (i.e. NC p0’s)neutrinos – weak probe of nuclear (low E) and hadronic (high E) structureelastic :axial form factors of the nucleoninclusive : quark structure of the nucleon (parton distribution functions)nucleons are confined in nuclei and are not free expect deviations from n – free nucleon (p or n) interactions quark densities modifications in nuclei (EMC effect)(today we have very high intensity neutrino beams that allow us to study all this)

n -sections

T2K ND280 Off-Axis Event Gallery15

Probing Nucleon StructureCharged lepton scattering data show that quark distributions are modifiedin nucleons confined (bound) in a nucleus:PDFs of a nucleon within a nucleus are different from PDFs of a free nucleon.The EMC effect (valence region) does not shows a strong A dependence for F2A / F2Dn probes same quark flavorsas charged leptons butwith different “weights” expect different shape expect different behavior ? x 1? is shadowing the same ?F2A / F2DNuclear effects in neutrino scattering are not well established, and have not beenmeasured directly : experimental results to datehave all involved one target materialA / D Ratio (e / m DIS)per experiment (Fe or Pb or ).Should be studied using D targets.anti-shadowingshadowingEMC effectxBj

How To Make a nm Beam(conventional horn focused beam)FocusingDevicesProton TargetBeamDecay PipemnmSimon van der Meerp(1925 2011)Focusing device: Electromagnetic HornBeam DumpAluminumCurrentp beamBBp p I [ A] 10 65r [m]B 4.3 T , r 15 mm, I 320kAトロイダル磁場B [T ] pure nm beam ( 99%)ne ( 1%) from p m e chain and K decays (Ke3)nm / nm can be switched by flipping polarity of Horns

The NUMI Beam (FNAL)NuMI (Neutrinos at the Main Injector)120 GeV protons from Main Injector, 300 - 350 kW90 cm graphite target675 m decay tunnelBy moving the production target w.r.t. 1st hornand the distance between horn 1 and horn 2one can modify the n spectrum:LE (peak 3 GeV) ME (peak 6 GeV)Flux determinationmuon monitor dataspecial runs (vary beam parameters)nm – electron scatteringlow–n methodexternal hadron production data

The Off-Axis T2K n BeamDm2 3x10-3eV2qTarget 3 Horns Decay Pipe2.50p decay KinematicsVery narrow energy spectrum(almost monochromatic beam)Neutrino beam energy “tuned” tooscillation maximumEn (GeV)0 Enmax [GeV] 2 nm fluxSuper-K.OA0 OA2 OA2.5 OA3 30q [mrad ]neutrino energy En almost independentof parent pion energy2.5 3 horn focusing cancels partially the pTdependence of the parent pionpp (GeV/c)

Quasi-Elastic ScatteringEnQE mn2 (m p Eb ) 2 mm2 2(m p Eb ) Em2(m p Eb Em pm cos m ) 2QQE mm2 2 EnQE Em Em2 mm2 cos mEREC ETRUE ?QREC QTRUE ?)

n CCQE scatteringconsidered a possible standard candle for n oscillation experiments (En 1 GeV)En and Q2 can be determined from outgoing m energy and angleMiniBooNENOMADRelativistic Fermi Gasmodel axial form factorsT. Katori 30% discrepancy in the QE x-section measurements between recent exp.identification of QE events (purity, backgrounds, )reconstructed En energyaxial mass MAnuclear effects, FSI, two body currents (MEC), tension between datasets and RFG model : increase MA in the axial FF ?

And If Experiments “Do Not Agree” ?NOMAD data consistent with “standard” QE prediction (with MA 1.0 GeV)MiniBooNE data is well above “standard” QE prediction ( 30%)(increasing MA 1.35 can reproduce s)

And If Experiments “Do Not Agree” ?or how neutrino physicists discovered nuclear physicsrecognize thatnucleons are not freein a nucleus(the RFG model doesnot work)many models and authorsincluding nuclear effects :correlations (SRC)two body currents (MEC)2p2hTEMFSI MA 1 GeV

What About En ?input En Dirac deffects of1) single nucleon(RFG smearing)2) multi nucleon scattering(20 -30% of events off correlated pairs)mN Em mm2 2QEQEEn EREC mN Em pm cos m

MiniBooNE @ FNALLiquid Scintillator CH2 target4π detector, complete angular coverageGood lepton reconstruction & pion rejectionEssentially blind to details of the nucleon final state in CC eventsDetect both scintillating light and Cherenkov light

n / anti-n CCQE -Sections d2s/dTmdcosqmflux averaged doubly differential cross sectionslargely model independent measurement of muon kinematicsOlder experimental data is consistent with dipole axial FF and MA 1.015 GeV.New data also described with dipole axial FF but require MA 1.35 GeVOld resonance scattering data (e.g. via D production) MA 1.3 GeV

anti-n d2s/dTmdcosqmTm (GeV)It is clear that the RFG model assumingMA 1 GeV does not adequatelydescribe these data in shape or innormalization.PRD 88, 032001 (2013)

The MINERnA Detector120 plastic scintillator modules for tracking and calorimetry ( 32k readout channels)Construction completed in Spring 2010. He and H20 targets added in 2011MINOS Near Detector serves as muon spectrometer (limited acceptance)nuclear targets: He, C, H20, Fe, Pbfully active scintillator tracker

9” H20625 kgNuclear TargetsActive Scintillator ModulesLiquid He250 kgWaterHe1” Fe / 1” Pb322 kg / 263 kg1” Pb / 1” Fe263 kg / 321 kg3” C / 1” Fe / 1” Pb160 kg / 158 kg / 107 kgTrackingRegion0.3” Pb225 kg.5” Fe / .5” Pb162 kg / 134 kg

n CCQE Events in MINERnAMeVVertex Energynm p m nRecoil EnergyRegionTRACKERn BeamECALModule number nm n m pHCALMINOS NDVertex EnergyRecoil EnergyRegionTRACKERECALHCAL

anti-n / n CCQE -Sections ds/dQ2(flux averaged)RFG, SFRFG, SFMA 1.35MA 1.35TEMTEM

Conclusions CCQERecent CCQE measurements on nuclear materials are consistent :a significant enhancement in the normalizationthat grows with decreasing muon scattering angleis observed compared to the expectation with MA 1.0 GeV.1) a significant enhancement ( 30%) in the normalization2) a significant deficit of events is observed at low Q2 (Q2 0.1 GeV2)3) a significant excess of events is observed at larger Q2 (Q2 0.3 GeV2)The RFG model assuming MA 1 GeV does not adequatelydescribe these data in shape nor in normalizationThe interpretation of MINERnA data suggests thatthe resulting final-state pairs would be predominantly ppin neutrino scattering and nn in anti-neutrino scattering.(these results are consistent with the observation inquasi-elastic e – C scattering suggesting that multi-bodyfinal states are dominated by initial-state np pairs [JLab])

Inclusive Scatteringin principle ignore Xin reality need Xto reconstruct En calorimetricallyEn Em EXcross section build up: elastic 1p np K (“schematic”)

T2K CC Inclusive n ScatteringND280

T2K Off-Axis nm Analysis0.6 En 2 GeV tailOff-Axis ND280 detector

T2K CC Inclusive n cross sectionsdoubly differential flux averaged cross section d2s /dp dcosq

T2K CC Inclusive n cross sections

Minerna Inclusive n –sectionsMINOS NDmatchedtrackEvent selection criteria:single muon track in MINERnAwell reconstructed and matched into MINOS NDreconstructed vertex inside fiducial tracker regionnuclear targets : z position consistent with nuclear targetrecoil energy EREC reconstructed calorimetrically :En Em EREC

An Event from Target 3CFePbviewlookingupstreamStrip Numbernm N m XModule Number