Accelerator neutrino experiments

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1 Accelerator neutrino experiments Jennifer Thomas University College London Thanks to s.brice, p.vahle, d.wark

2 Accelerator neutrino experiments Direct observation of tau neutrinos DoNUT Present neutrino oscillation results k2k, minos, opera, (lsnd,mini-boone) Plans for next generation long baseline experiments Experiments of general interest Cross sections : sci-boone, minerva t2k, nova conclusion 2

3 Neutrino sector status (2007) iδ ν e c12 s c13 0 s13e ν 1 iα/2 ν μ = -s12 c c23 s e 0 ν 2 -iδ iα/ 2+iβ ν τ s23 c23 -s13e 0 c e ν 3 Normal hierarchy Inverted hierarchy 3light neutrino flavours: e,μ,τ (m 3 ) 2 (m 2 ) 2 (m 1 ) 2 Δm 2 21 Δm 2 21 : ( ) 10-5 ev 2 TAN 2 θ 12 : Δm 2 32 (m 2 ) 2 ν e ν μ ν τ Δm 2 31 Δm 2 32 : ( ) 10-3 ev 2 sin 2 θ 23 : SIN 2 θ δ : unknown Hierarchy : unknown Δm 2 21 (m 1 ) 2 (m 3 ) 2 m lightest < 2.2 ev Dirac or Majorana: unknown m 2 lightest m 2 lightest [updated from Gonzalez-Garcia PASI 2006] 3

DONuT: Direct Observation of ν τ Analysis complete 9 ν

4 DONuT: Direct Observation of ν τ Analysis complete 9 ν τ found in 578 total ν Background ~1.5 events (charm + hadronic int) Preliminary x-section results (cc) ντ Ν τ X relative to νμ, νe for energy-indpdt part ( ) ( ) = 1.14 ± 0.45 σ( ν τ ) σ ν τ σ ν e ( ) σ ν μ = 1.23 ± 0.44 ν τ Ν τ X μ ν μ ν τ Proof of principle for opera 4

5 2-3 long baseline concept iδ ν e c12 s c13 0 s13e ν1 iα/2 ν μ = -s12 c c23 s e 0 ν2 -iδ iα/2+iβ ντ s23 c23 -s13e 0 c e ν3 ν μ spectrum Monte P = 2 Spectrum ratio ( νμ νμ) Carlo Unoscillated Oscillated Δm L 1 sin θ sin Monte Carlo E Δm 2 32 Δm 2 21 (m 3 ) 2 (m 2 ) 2 (m 1 ) 2 ν e νμ ν τ (m 2 ) 2 (m 1 ) 2 (m 3 ) 2 Δm 2 21 Δm 2 31 m 2 lightest m 2 lightest 5

6 K2K: 1 st long baseline experiment Confirmation of sk result 300m near detector 250km baseline SuperK far detector 112 observed ν μ cc expected 58 single-ring μ-like evts L/E=0.25Km/MeV Phys.Rev.D 74, ,2006 6

7 MINOS: 2-3 sector precision measurement Far detector Far Detector: Soudan, Minnesota 5.4 kton mass 484 steel/sci planes 8x8x30 m 3 2.3% absolute calibration B-field~1.3T 735 km baseline Near Detector: Fermilab, Illinois 1km from target 1 kton mass 282 steel planes 3.1% absolute calibration 153 scintillator planes, 3.8x4.8x15 m 3 Bfield~1.3T Near detector l/e=0.4km/mev 7

8 Neutrinos from the Main Injector (NuMI) 2.5e20 p.o.t. Used in new analysis 10 μs spill 120 GeV protons every 2.4s 180 kw typical beam power protons per pulse Neutrino spectrum changes with target and horn position 8

9 MINOS: near detector exploitation Identical Detectors ND and FD ν Calorimeter Spectrometer Fiducial Volume Use ND spectra for: Beam MC tuning => flux measurement FD spectrum prediction takes advantage of all cancellations Cross section Detector thresholds Secondary hadron production (1 st order) 9

MINOS Beam MC tuning Use different beam configurations to learn about beam Discrepancies in different places pointed to beam issues Parameterize Fluka2005

10 MINOS Beam MC tuning Use different beam configurations to learn about beam Discrepancies in different places pointed to beam issues Parameterize Fluka2005 hadron production re-weight as f(x F,p T ) Horn focusing, beam misalignments, neutrino energy scale, ν cross section, NC background Weights applied vs p z & p T 10

with pdf based on 6 parameters reflecting confidence in

11 minos near detector ν μ cc selection Particle IDentification Distribution Finding muons is main approach Select cc events with pdf based on 6 parameters reflecting confidence in event s track like characteristics NC-like CC-like All Energies 11

12 MINOS FD Spectrum Prediction x = Measured ND spectrum is transported to FD E fd is not just E nd /r 2 Pion/Kaon decay kinematics encapsulated in matrix MC to provide corrections (resolution, acceptance) Hadron production changes are 2nd order : affects ND and FD together P( νμ νx) = sin (2θ )sin (1.27Δm L E ) 6.2σ effect <10GeV 12

13 Sector 2-3 allowed parameter space sin Δm sin ϑ = 2ϑ = = ev Statistics limited 13

14 MINOS Outlook M C MINOS MC Muon neutrino disappearance 6e20 pot by end 2008 Anti-neutrino oscillations in neutrino beam anti-ν running > 09 Electron neutrino appearance by end 2007 Search for exotics Sterile neutrinos Neutrino decay/de-coh 14

Opera : appearance of tau neutrinos ν μ ν τ μ

Physics goals: Verify oscillation is to ντ

04km/MeV (17GeV E ν ) 12 events expected, 1

Prediction, extraction, scanning Turn on sep

15 Opera : appearance of tau neutrinos ν μ ν τ μ spectrometer: Dipolar magnet + RPC chambers Physics goals: Verify oscillation is to ντ Search for ν e appearance cngs L/e = 0.04km/MeV (17GeV E ν ) 12 events expected, 1 bkg, after 5 yrs May 07 cosmic test: Prediction, extraction, scanning Turn on sep kbricks Full compliment mar 08 Emulsion Cloud Chamber 1 mm Pb τ 15

Future long baseline : goals ν μ ν e iδ ν e c12 s12 0 1 0 0 c13 0 s13e 1 0 0 ν 1 iα/2 ν μ = -s12 c12 0 0 c 23 s23 0 1 0 0 e 0 ν -iδ 2 iα/2+iβ ν τ 0 0 1 0 -s23 c23 -s13e 0 c13 0 0 e ν 3 Δm 2 31 [ev2 ]

16 Future long baseline : goals ν μ ν e iδ ν e c12 s c13 0 s13e ν 1 iα/2 ν μ = -s12 c c 23 s e 0 ν -iδ 2 iα/2+iβ ν τ s23 c23 -s13e 0 c e ν 3 Δm 2 31 [ev2 ] 10-2 high precision 2-3 parameters observation of ν e events θ 13 : present sin 2 θ 13 <0.04 cp violation δ mass hierarchy 10-3 (m 3 ) 2 (m 2 ) 2 (m 1 ) 2 Δm 2 21 sin 2 θ 13 Schwetz hep/ph Δm 2 32 Δm 2 21 m 2 lightest (m 2 ) 2 (m 1 ) 2 ν e νμ ν τ (m 3 ) 2 Δm 2 31 m 2 lightest 16

17 Future long baseline: goals P( ν ν ) = sin sin 2 μ e + sin ( Δ mal) θ23 θ13 Δ 2 31 ( Δ31 mal) sin ( al) ( al) cos θ23sin 2θ 12 Δ 2 21 sin( Δ31 mal) sin( al) + cos δsin2θ 23sin2θ 12sin2θ13cos Δ32 Δ31 Δ21 ( Δ31 mal) ( al) + sinδsin2θ sin2θ sin2θ sinδ Measure θ 13 present limit: Sin 2 2θ 13 <0.15 Sin 2 θ 13 <0.04 Sinθ 13 <0.2 θ 13 <11.5 o CP violation and matter effects are ambiguous for half possible values of δ e ν e e P atmos P solar a G N sin( Δ3 1maL) sin( al) Δ31 Δ2 1 ( Δ31 mal) ( al) ν e ij F e / 2 (4000km) Δ Δm L E ij / L(km), E(GeV), m(ev) 1 interference Second experiment with different l (or E) will give complimentary information for mass hierarchy 17

sci-boone High granularity detector in NuMI beamline : good for noνa wide scope : several z x-sec measurements at a few GeV

18 Future long baseline: tools Off axis beams TargetHorns Decay Pipe Near Detector θ Far Detector Reduces high energy tail and so NC π 0 background Reduces ν e contamination from K and μ decay due to decay kinematics X-sec measurements: Minerνa and sci-boone High granularity detector in NuMI beamline : good for noνa wide scope : several z x-sec measurements at a few GeV K2K SciBar detector in the FNAL Booster Neutrino Beamline Precision measurement of x-secs for T2k : beam well matched e/gev 18

19 NOνA Far detector: 14 kton, fully active segmented 14.5 mrad off NuMI beamline axis 810 km baseline, E ν ~2gev, l/e=0.4km/mev Near Detector Functionally same as FD Will move to sample different backgrounds optical fibre 19

20 Noνa: future reach Matter effect in Nova has longest baseline: 810km run with ν and ν Matter effects increase (decrease) oscillations for normal (inverted) hierarchy for ν Hierarchy can be resolved if θ 13 near to present limit 20

T2K: jparc to Super-K Near Det @ 280m 2.

4km/mev π 0 from neutral current interactions important

21 T2K: jparc to Super-K Near 280m 2.5mrad(off-axis) Inside ua1/nomad magnet for momentum measurement Sandwich calorimeters/tracker for precision beam measurement E ν ~0.8GeV, l/e=0.4km/mev π 0 from neutral current interactions important background Ingrid 280m (on-axis) Iron scintillator tracker Determines beam profile and direction 21

22 T2K: Sensitivity CP phase δ (degrees) θ 23 = π/4 (sin 2 2θ 23 = 1.0) θ 23 = (sin 2 2θ 23 = 0.9) θ 23 = (sin 2 2θ 23 = 0.9) Δm 2 13 = 2.5x10-3 ev 2 Δm 2 12 = 8.2x10-5 ev 2 tan 2 θ 12 = 0.4 CP phase δ (degrees) Δm 2 13 = 2.5x10-3 ev 2 Δm 2 13 = 1.9x10-3 ev 2 Δm 2 13 = 3.0x10-3 ev 2 sin 2 2θ 23 = 1 Δm 2 12 = 8.2x10-5 ev 2 tan 2 θ 12 = sin 2 2θ sin 2 2θ 13 Plot from I. Kato/T2K 22

23 T2k and noνa: latest T2K: Nova: Hoping for first data April 2009 Ramp up to 750kW source by 2012 Hoping to start detector construction in 2010 and have 700kW source on same timescale Many inponderables Reasonable assumptions Mezzetto

24 conclusions A decade of discovery has produced 5 effective parameters: sin 2 θ 23,tanθ 12, Δm 2 23,Δm2 21 and its sign Lessons learned for the future Near detector.is your best friend! Beam flexibility.is next Still to be determined: θ 13, sign (Δm 2 23 ), δ CP Maybe δ CP, Δm 2 23 within reach of next experiments if sin 2 2θ 13 >0.01 Point is to find an underlying symmetry: focus on precision measurements of parameters Near detectors Off axis beams and flexibility Cross sections Detector precision 24

25 BACKUP SLIDES 25

26 MINOS Near Detector: Particle IDentification Input Variables 26

27 What Changed? Improvements: reco & selection shower modelling Data sets: Pre-shutdown Post-shutdown 27

28 NuMI Alignment Align the center of ν beam to the Far Detector in the Soudan mine. Goal is within 12 m. Fermilab to Soudan surface done using GPS determined vector to 0.01 m horiz., 0.06 m vertical Soudan surface to 27 th level 0.7 m per coordinate Fermilab surface to underground gyrotheodolite with mrad precision 11 m at Soudan Transverse alignment of baffle, target and horn at 0.5 mm 28

29 Event generator Neutrino-nucleus interactions were generated using the NEUGEN3 neutrino event generator (H. Gallagher, Nucl.Phys.Proc.Suppl. 112: , 2002) Quasi-Elastic: dipole parametrization of form factors with ma=0.99 GeV/c 2 (BBBA05 Bradford et al. Nucl.Phys.Proc.Suppl.159: ,2006) Resonance Production: Rein-Seghal model for W<1.7 GeV/c 2. (Annals Phys. 133: 79, 1981) DIS: Bodek-Yang modified LO model. For W<1.7 GeV tuned to electron and neutrino data in the resonance / DIS overlap region. (Bodek-Yang, Nucl. Phys. Proc. Suppl. 139: , 2005 and H. Gallagher, NuINT05 Proceedings) Coherent Production: Rein-Seghal (Nucl. Phys. B 223: 29, 1983) 29

30 Beam Matrix Prediction & Near Detector Data : RunI/RunIIa 30

31 Effect of MC tuning on the measurement Far Predicted Spectra using the Beam Matrix and with/without hadron production tuning Using tuned MC for energy smearing and acceptance corrections Using nominal MC for energy smearing and acceptance corrections Ratio of Far Prediction using the Beam Matrix and with/without hadron production tuning Using tuned MC for energy smearing and acceptance corrections Using nominal MC for energy smearing and acceptance corrections Using Beam Matrix Method, hadron production tuning does not affect the Unoscillated prediction (obtained from the ND data) by more than 1-2%. However, its use improves the MC (make it more similar to the data) and therefore uncertainties due to energy smearing- unsmearing and acceptance become smaller. 31

32 MINOS: new analysis 2007 New PID has higher overall efficiency and higher background rejection (less contamination from NC interactions) 32

33 MINOS: Near Detector Data/MC normalized to area Event Vertices (X Y Z) Track Angles (X Y Z) 33

34 MINOS: systematic uncertainties The main remaining systematic uncertainties are Near/Far normalization, absolute hadronic energy scale and NC contamination Overall systematics reduced by use of near detector Uncertainty Shift in Δm 2 (10-3 ev 2 ) Shift in sin 2 (2θ) Near/Far normalization ±4% <0.005 Absolute hadronic energy scale ±10% <0.005 NC contamination ±50% All other systematic uncertainties <0.005 Total systematic (in quadrature) Statistical error (data)

35 Data Sample FD Data Expected ( Unoscillated) Data/Prediction ν μ CC like All (4.4 σ) ν μ CC like (<10 GeV) (6.2 σ) ν μ CC like (<5 GeV) (6.5 σ) For energies between 0-10 GeV a deficit of 38% is observed, with respect to the no disappearance hypothesis. 35

MINOS Detector Technology Scintillator strip

alternate planes U,V optical fibre readout to

36 MINOS Detector Technology Scintillator strip M16 PMT 2.54 cm Fe Extruded PS scint. 4.1 x 1 cm Near and Far Detectors are functionally identical: 2.54cm thick 1.3 T magnetised steel plates co-extruded scintillator strips orthogonal orientation on alternate planes U,V optical fibre readout to multi-anode PMTs U V planes +/ Clear Fiber cables WLS fiber Multi-anode PMT 36

37 LSND result Excess of ν e events in a ν μ beam 87.9 ± 22.4 ± 6.0 over background ~4σ evidence for oscillation Δm 2 different from the solar and atmospheric Δm 2 s. With 3 standard model neutrinos 2 independent Δm 2 s could lsnd result be evidence for a sterile neutrino? Mini-boone sees no excess in ν μ ν e l/e=0.001kev/km L/E=0.001km/MeV 37

38 0-3 GeV 3-6 GeV 38

39 After θ 13 P ~ (P atmos ) 1/2 + (P solar ) 1/2 + interference terms L=735km probability E (GeV) Much information within :± Δm 2,δ, matter effect Effects are non-trivial to disentangle Complimentarity with different L,E and production 39

40 MINOS NC analysis : near detector Spectra Search for sterile ν MC error band beam, cross-section and energy scale uncertainties Fogli et al. 3+1 model 40

41 MINOS: ν μ ν e appearance status Using full power of the near detector Comparison of mc/data shows discrepency Same effect in muon removed cc sample points to shower modelling Bkgd spectrum will be derived from nd data νμ μ νμ Hadronic n shower 41

42 Future long baseline: tools x-sec measurements : basic foundation of ν probes CCQE x-sec is best known search for tiny signals: background estimate is paramount eg: high y cc events which oscillate cannot be estimated in near detector 2 experiments being mounted to address these issues Compilation of ν μ CC Quasi-Elastic x-section Measurements 42

43 MINOS: measurement vs prediction P( νμ νx) = sin 2 (2θ )sin 2 (1.27Δm 2 L E ) P(χ 2,n.d.f) = 0.18 χ 2 /n.d.f = 139.2/36 =3.9 χ 2 /n.d.f = 41.2/34 = 1.2 P(χ 2,n.d.f) = 0.18 No Disappearance Hypothesis Oscillation Hypothesis best fit 6.2σ effect below 10GeV 43

Long Baseline Neutrino Experiments

Physics in Collision, 27/6/2008 Mark Thomson 1 Long Baseline Neutrino Experiments Mark Thomson Cavendish Laboratory University of Cambridge Introduction Neutrino Beams Past Experiments: K2K Current Experiments: