Accelerator-based neutrinos Lecture 1 Kendall Mahn 26/08/2015, INSS K.Mahn, Acc-nu sources 1 Neutrino sources The Sun (fusion) GalacGc and Our atmosphere extra-galacGc sources (e.g SN) RadioacGve Accelerators decays Reactors 26/08/2015, INSS K.Mahn, Acc-nu sources 2 Neutrino sources The Sun (fusion) GalacGc and Our atmosphere extra-galacGc sources (e.g SN) At solar neutrino energies, mean free path through lead is 1 light year Making precision neutrino measurements require enormous detectors and intense sources RadioacGve Accelerator-driven neutrino beams are one such method Accelerators decays Reactors 26/08/2015, INSS K.Mahn, Acc-nu sources 3 Physics of accelerator based ν experiments Neutrino oscillaon • Measurements of neutrino mixing parameters • Nonstandard neutrino mixing Electroweak tests • Lorentz violaon 2 • Measurement of sin θW • Discovery of νµ, ντ Neutrino interacGons • Charged current interacGons • Neutral current interacGons • Deep inelasGc scaering • Structure funcGons Detector R&D 26/08/2015, INSS K.Mahn, Acc-nu sources 4 Physics of accelerator based ν experiments Neutrino oscillaon K2K, MINOS, T2K, NOvA • Measurements of neutrino mixing parameters OPERA (& ICARUS) • Nonstandard neutrino mixing LSND, Karmen, MiniBooNE, MicroBooNE CHORUS, NOMAD Electroweak tests • Lorentz violaon CCFR, CDHS, NuTeV 2 • Measurement of sin θW Gargamelle, DONUT • Discovery of νµ, ντ CHARM Neutrino interacGons • Charged current interacGons ANL, BNL bubble chamber • Neutral current interacGons experiments • Deep inelasGc scaering SciBooNE, MINERvA • Structure funcGons COHERENT, CONNIE Detector R&D Incomplete list of experiments; later lectures will ArgoNeuT cover future and proposed experiments PEANUT Most experiments cover mul;ple physics topics 26/08/2015, INSS K.Mahn, Acc-nu sources 5 Physics of accelerator based ν experiments Neutrino oscillaon K2K, MINOS, T2K, NOvA • Measurements of neutrino mixing parameters OPERA (& ICARUS) • Nonstandard neutrino mixing LSND, Karmen, MiniBooNE, MicroBooNE Focus for this set of talks CHORUS, NOMAD Electroweak tests • Lorentz violaon CCFR, CDHS, NuTeV 2 • Measurement of sin θW Gargamelle, DONUT • Discovery of νµ, ντ CHARM Neutrino interacGons Neutrino cross secGons covered by K. McFarland • Charged current interacGons ANL, BNL bubble chamber • Neutral current interacGons experiments • Deep inelasGc scaering SciBooNE, MINERvA • Structure funcGons COHERENT, CONNIE Detector R&D Neutrino detecGon techniques covered by K. Scholberg ArgoNeuT PEANUT 26/08/2015, INSS K.Mahn, Acc-nu sources 6 Open quesGons about neutrino mixing Open questions in neutrino mixing # νe & #Ue1 Ue2 Ue3 & # ν1 & Flavor eigenstates % ( % ( % ( Mass eigenstates (coupling to the W) νµ = Uµ1 Uµ2 Uµ 3 ν2 (definite mass) % ( % ( % ( $ ντ ' $Uτ1 Uτ 2 Uτ 3 ' $ν3 ' Unitary PMNS mixing matrix Three observed flavors of neutrinos (νe, νµ , ντ) means U is represented by three independent mixing angles (θ , θ , θ ) and a CP-violang phase δ 12 23 13 Measurements by accelerator-based experiments Is θ23 mixing maximal (θ23=46°±3°) Is there CP viola;on (non- PDG2014 PDG2014 zero δ?) 26/08/2015, INSS K.Mahn, Acc-nu sources 7 Open quesGons about neutrino mixing Open questions in neutrino mixing 3 2 Δm 32 > 0 2 2 2 Δmij = mi − m j 2 2 Δm 21 1 2 Neutrino mass squared (m€ i ) Neutrino oscillaon measurements are sensiGve to the interference of the mass eigenstates (Δm2) Two observed mass “splings”, determined from atmospheric/accelerator and solar/reactor neutrino experiments, respecGvely 2 2 -3 2 § Δm (atmospheric) = |Δm 32|~ 2.4 x 10 eV 2 2 -5 2 § Δm (solar) = Δm 21 ~ 7.6 x 10 eV 26/08/2015, INSS K.Mahn, Acc-nu sources 8 Open quesGons about neutrino mixing Open questions in neutrino mixing 3 2 2 Δm 21 2 Δm 32 > 0 1 m2 2 Δ 32 < 0 2 Δm 21 1 3 2 Neutrino mass squared (mi ) 2 The sign of Δm 32, or the “mass hierarchy” is sGll unknown 2 § Normal “hierarchy” is like quarks (m1 is lightest, Δm 32 >0 ) 2 § Inverted hierarchy has m3 lightest (Δm 32 <0) What is the mass hierarchy? 26/08/2015, INSS K.Mahn, Acc-nu sources 9 Oscillaon probabiliGes Oscillation probabilities 2 2 |Δm 32| >> Δm 21, producing high frequency and low frequency oscillaon terms ( 1.27Δm2 L + ( 2.54Δm2 L+ P 4 Re U U * U * U sin2 ij 2 Im U U * U * U sin ij αβ = δαβ − ∑ [ βi αi βj αj ] * - + ∑ [ βi αi βj αj ] * - i> j ) E , i> j ) E , 2 2 2 If choose L, E, such that sin (Δm 32L/E) is of order 1, then Δm 21 terms will be € small. Then... ν “disappear’’ into ν , ν µ e τ ( 1.27 m2 L + 2 2 Δ 32 P(νµ → ν µ ) ≅ 1− sin 2θ23 sin * - ) E , A small amount of νe will “appear’’ 2 2 Δm 31 ~ Δm 32 € 2 2 2 2 ' 1.27Δm31L * P(νµ → νe ) ≅ sin 2θ13 sin θ23 sin ) , ( E + Only leading order terms shown 26/08/2015, INSS K.Mahn, Acc-nu sources 10 € Accelerator-basedAccelerator based neutrino neutrino sources sources 95m Decay region Neutrino beam π+ 30 GeV Carbon 3 MagneGc Pions and kaons Beam Proton beam Target focusing decay to neutrinos dump ``horns” To measure νµ disappearance, and νe appearance requires a νµ source* § Atmospheric neutrinos include both νe and νµ from producon § Accelerator based beams are pure νµ from a proton -> meson -> decay chain: § Typically >99.9% νµ § ProducGon of neutrinos is “known”, scalable with accelerator improvements § Also possible to create anGneutrino source *There are other ways to probe oscilla;on physics with intense sources, more later 26/08/2015, INSS K.Mahn, Acc-nu sources 11 Oscillaon probabiliGes Oscillation probabilities νµ to νe appearance probability expansion: E A =2 √2G N ν F e ∆m2 32 Key players: 2 -3 2 § |Δm 32|~ 2.4 x 10 eV (atmospheric mass spling) § Mixing angles: θ12, θ23, θ13 Approxima;on from § CP-violang phase δCP M. Freund, PRD 64, 053003 Neutrinos vs. anneutrinos probability depends on δCP, mass hierarchy (sign 2 of Δm 32 ) • Mass hierarchy is determined through energy dependence of νe, νµ interacGons in maer (maer effects, A terms) 26/08/2015, INSS K.Mahn, Acc-nu sources 12 Oscillaon probabiliGes Oscillation probabilities νµ to νe appearance probability expansion: E A =2 √2G N ν F e ∆m2 32 Key players: 2 -3 2 § |Δm 32|~ 2.4 x 10 eV (atmospheric mass spling) § Mixing angles: θ12, θ23, θ13 Approxima;on from § CP-violang phase Subleading terms of δCPνµ to νe appearance depend on δCP, mass hierarchy, but interpretaon requires precision measurements of: M. Freund, PRD 64, 053003 Δm2 , θ (disappearance) and Δm2 , θ and θ Neutrinos vs. anneutrinos probability depends on 32 23 21 δ12CP, mass hierarchy13 (sign 2 of Δm 32 ) Measurements of νµ to νe (and νµ to νe ) appearance are sensi;ve to • Mass hierarchy is determined through energy dependence of currently unknown physics νe, νµ interacGons in maer (maer effects, A terms) 26/08/2015, INSS K.Mahn, Acc-nu sources 13 Oscillation probabilities 2 2 2 ( 1.27Δm32 L + P(νµ → ν µ ) ≅ 1− sin 2θ23 sin * - ) E , 2 2 Measure: Δm 32 and sin 2θ23 Experimental controls: § Fix beam energy (E) € § Place a detector at L, the (first) oscillaon maximum Why not place two detectors, one at L and one at 2L? P(ν ) µ Flux decreases as 1/L2: Osc maximum Event rate scales with flux: N = Φ x σ x ε P(ν ) ξ Event rate is (currently) too small 26/08/2015, INSS K.Mahn, Acc-nu sources KARMEN website graphic 14 Long baseline experiments 2 2 2 ( 1.27Δm32 L + P(νµ → ν µ ) ≅ 1− sin 2θ23 sin * - +... ) E , Unknown road to Unknown road - Google Maps http://maps.google.com/maps?hl=en&tab=wl Δm2 ~3x10-3 eV2, want sin2(Δm2 L/E) to be of order 1 32 To see all the details that are visible on the screen, use the "Print" link next to the map. Tokai To € Kamioka (T2K) experiment: MINOS experiment: Eν(peak) ~0. 6GeV, L=295km Eν(peak) ~3 GeV, L=735km First part of lecture: What are the physics results from long baseline experiments? ©2011 Google - Imagery ©2011 TerraMetrics - 26/08/2015, INSS K.Mahn, Acc-nu sources 15 1 of 1 4/23/11 10:27 AM Accelerator-basedThe Tokai-to- Kamiokaexperiment experiment example: T2K The physics so far: νµ to νe (and νµ to νe) appearance: § Discovery of νe appearance (2013) § Search for presence of appearance Neutrino flux at SK with anGneutrinos; necessary step (no oscillaon) toward future CPV searches νµ, νµ disappearance: § World’s best measurement of θ23 § With anGneutrinos: test of NSI or CPT theorem 26/08/2015, INSS K.Mahn, Acc-nu sources 16 νµ disappearance at T2K For a fixed baseline (L=295km) 2 2 2 ( 1.27Δm32 L + oscillaon probabiliGes depend on P(νµ → ν µ ) ≅ 1− sin 2θ23 sin * - +... ) E , the neutrino energy Eν 2 2 Data Extract Δm , sin θ23 from observed 60 change in overall rate and spectrum MC€ Unoscillated Spectrum 40 MC Best Fit Spectrum § Energy esGmated using lepton NC MC Prediction Events/0.10 GeV momentum, angle and assumed 20 CCQE kinematcs 0 0 2 4 > 5 PRD 91, 072010 (2015) Reconstructed ν Energy (GeV) 10 1 10−1 10−2 0 2 4 > 5 Osc. to unosc Events/0.1 GeV Reconstructed ν Energy (GeV) 26/08/2015, INSS K.Mahn, Acc-nu sources 17 T2K observed event distributions) 4 /c 2 T2K data favors maximal disappearance 3.2 eV -3 § Provides best constraint on θ to date, SK joint OA 23 (10 3 consistent with maximal (45°) mixing 2 32 m ∆ 2.8 T2K joint OA 2.6 2.4 2.2 MINOS joint OA 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 ) 4 -2 /c 2 eV -3 -2.2 MINOS joint OA (10 2 32 PRD 91, 072010 (2015) m -2.4 ∆ -2.6 -2.8 T2K joint OA -3 SK joint OA 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 2 sin θ23 26/08/2015, INSS 18 K.Mahn, Acc-nu sources T2K observed event distributions) 4 /c 2 T2K data favors maximal disappearance 3.2 eV -3 § Provides best constraint on θ to date, SK joint OA 23 (10 3 consistent with maximal (45°) mixing 2 32 m ∆ § Atmospheric measurements also 2.8 T2K joint OA important (SK, IceCube) 2.6 Best constraint on mass spling from MINOS experiment 2.4 • Energy uses lepton and hadronic state 2.2 MINOS joint OA 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 ) 4 -2 /c 2 eV -3 -2.2 MINOS joint OA (10 2 32 PRD 91, 072010 (2015) m -2.4 ∆ -2.6 -2.8 T2K joint OA -3 SK joint OA Phys.