The NOνA Neutrino Experiment

Transcription

1 The NOνA Neutrino Experiment Thomas Coan Southern Methodist University For the NOνA Collaboration 11th ICATPP Villa Olmo, Como 2009

2 Outline NuMI Off-Axis νe Appearance Experiment Neutrino Physics Motivation Fermilab Neutrino Beam Upgrade NOνA Detector Design and Construction NOνA Sensitivities Timeline & Summary Como Oct 09 2

3 Neutrinos Mix Solar νs Reactor νs Atmospheric νs Accelerator νs Homestake, Gallex, SAGE, Super-K, SNO, Borexino KamLAND, CHOOZ, Kamiokande, Super-K K2K, MINOS, MiniBOONE flavor eigenstates ν e ν µ ν τ Neutrinos change flavor Neutrinos have mass and mix = U e1 U e2 U e3 U µ1 U µ2 U µ3 U τ1 U τ2 U τ3 ν 1 ν 2 ν 3 mass eigenstates Como Oct 09 3

4 PMNS Leptonic Mixing Matrix ν α = iu αi ν i U αi can be written w/ 3 mixing angles and 1 phase and w/ c ij cos θ ij and s ij = sin θ ij atmospheric cross-mixing solar c 13 0 s 13 e iδ c 12 s 12 0 U = 0 c 23 s s 12 c s 23 c 23 s 13 e iδ 0 c = c 12 c 13 s 12 c 13 s 13 e iδ s 12 c 23 c 12 s 23 s 13 e iδ c 12 c 23 s 12 s 23 s 13 e iδ s 23 c 13 s 12 s 23 c 12 c 23 s 13 e iδ c 12 s 23 s 12 c 23 s 13 e iδ c 23 c 13 Mixing angle θ 13 unknown (sin 2 2θ 13 < 0.18). CP violating phase δ unknown. Como Oct 09 4

5 Neutrino Ignorance m 2? sin 2 θ 13?? sin 2 θ 13? Como Oct 09 5

6 Vacuum Oscillations Neutrinos propagate as mass eigenstates Interact as different (i.e., weak) eigenstates In absence of matter (key caveat) & to lowest order: P vac (ν µ ν e )=sin 2 θ 23 sin 2 2θ 13 sin 2 atm ( Oscillations result 2 2 atm 1.27 m2 32 (ev2 )L(km) E(GeV) Additional sub-dominant terms, sensitive to CPV phase δ: P δ (ν µ ν e )=Jsin sol sin atm (cosδcos atm +sinδsin atm ) J =sin2θ 12 sin2θ 23 sin2θ 13 cosθ 13 ν ν but NOνA s neutrinos travel though Earth... ) Como Oct 09 6

7 Matter Effects ν x Z ν x ν e W e e e e ν e ν e e scattering Hamiltonian modified Effective mass eigenstates & mixing angles altered P mat (ν µ ν e ) (1±2 E )P vac (ν µ ν e ) E R E R 12 GeV (earth s mantle) E(ν) 2 GeV 30% enhancement/suppression NOνA s long baseline key Como Oct 09 7

8 NOνA Goals at a Glance Observe ν µ ν e transition Measure θ 13 Determine mass hierarchy (sign of m 2 23) Measure sin 2 (2θ 23 ) w/ high precision Constrain δ CP Large neutrino luminosity & detector mass req d Como Oct 09 8

9 NOνA Collaboration 180+ scientists/engineers 27 institutions 4 countries Argonne National Laboratory University of Athens California Institute of Technology University of California, Los Angeles Fermi National Accelerator Laboratory Harvard University Indiana University Institute for Nuclear Research, Moscow Institute of Theoretical and Experimental Physics, Moscow Michigan State University University of Minnesota, Duluth University of Minnesota, Minneapolis The Institute for Nuclear Research, Moscow Technische Universität München, Munich State University of New York, Stony Brook Northern Illinois University, DeKalb Northwestern University University of South Carolina, Columbia Southern Methodist University Stanford University Texas A&M University University of Texas, Austin University of Texas, Dallas Tufts University University of Virginia, Charlottesville The College of William and Mary Wichita State University Como Oct 09 9

10 Off-Axis Beam Technique µ CoM: Lab Frame: ν E ν π E π 1+(E π /m π ) 2 θ 2 E ν (GeV) E(ν) ~independent of parent hadron E E π (GeV) Como Oct 09 10

11 Accelerator Upgrade post-tevatron era Booster Recycler MI target p: 8 GeV 120 GeV Recycler: p p storage ring slip-stack batches in Recycler single turn extraction into MI 53 MHz RF added MI cycle time: 2.2 s 1.33 s more 53 MHz RF Como Oct 09 11

12 Upgraded NuMI Beam 14.6 mrad off-axis ν beam 10 µsec spill every 1.3 sec medium energy tune GeV/p 700 kw beam power POT/yr Plan 3 yr ν µ & 3 yr ν µ running MC Como Oct 09 12

13 2-Detector Configuration NOνA FD 810 km (MINOS FD) 735 km θ = 14.6 mrad NOνA ND Near detector measures ν flux, measures background rates Far detector measures osc ν flux Como Oct 09 13

14 NOνA Far Detector Overview o Low-Z tracking calorimeter o Surface location 67 m o 14 kt total mass o 930 Detector planes Alternate x-y layers 73% active o Liquid scintillator cells 4 cm x 6 cm x 1540 cm 15.6 m 15.6 m o 1-sided readout/plane via avalanche photodiodes (APDs) Como Oct 09 14

15 NOνA Detector Atom To 1 APD pixel Liquid Scintillator Mineral oil solvent Primary scintillator: 4.1% (BW) pseudocumene Waveshifters: PPO + bis-msb typical charged particle path W D L Hollow PVC cells provide granularity 15% (BW) TiO: high reflectivity walls Horizontal cell: 3.87 cm x 6.0 cm x 15.4 m long Vertical cell: 3.76 cm x 5.7 cm x 15.4 m long Looped Wavelength Shifting Fiber Maximizes light collection: no mirrors Diameter = 0.7mm, K ppm Avalanche Photodiode QE = 85% Gain = 100 T_run = -15 C Como Oct 09 15

16 Why APDs Fiber Spectrum v. fiber length λ (nm) Como Oct 09 16

17 Far Detector Module Construction Epoxy Dispenser 16 Cell Full size Extrusion Die 32 Cell Module Module 12 Module Plane 30 Plane Blocks

18 Far Site & Building Barite (BaSO4) Concrete planks Excavated granite NOν νa Detector 1.98m 15.6m 1.13m Less is more Como Oct 09 18

19 Near Detector ND: 6 blocks + µ-catcher o surface (2010) o θ_beam = 100 mrad Surface MINOS tunnel o θ_beam = 14.6 mrad ND mass(es) o 222 T o 125 T active o 23 T fiducial N Elevation view along beamline 14.3 m 2.9 m Veto Target 4.2 m µ-catcher Shower containment MINOS Surface Building MINOS shaft NOvA cavern 105 m Plan view 1015 m 1015 meters

20 Expected e v. µ Signature Fine sampling ( 0.2 X 0 /plane): excellent e/µ separation Monte Carlo X X Y Z Y Z 50 planes 150 planes Como Oct 09 20

21 ν e CC event ν e p e - p π + E ν =2.5 GeV E e =1.9 GeV E p =1.1 GeV E π =0.2 GeV X Y 70 planes MC Z Como Oct 09 21

22 Background ν µ NC Event ν µ N ν µ p π o E ν = 10.6 GeV X MC E p = 1.04 GeV E πo = 1.97 GeV Y 60 planes Z Como Oct 09 22

23 Sensitivity to sin 2 (2θ 13 ) 0 δ (π) NOνA δ (π) NOνA Como Oct 09 23

24 Mass Ordering Discrimination Matter effects v. CPV from δ In general, sign ( m 2 ) req d for δ m ment. δ But, Nature may be kind e.g., assume P(ν e ) = 0.02 Measure P(ν e ). Favorable δ may exist. δ Otherwise, 3 rd m ment req d, e.g., T2K Como Oct 09 24

25 Sensitivity to Mass Ordering 95% C.L. : NOνA alone δ (π) NOνA Normal Hierarchy δ (π) Inverted Hierarchy NOνA Sin 2 (2θ 13 ) Sin 2 (2θ 13 ) Como Oct 09 25

26 Sensitivity to Mass Ordering (2) 95% C.L. : NOνA + T2K δ (π) NOνA + T2K Normal Hierarchy δ (π) NOνA + T2K Inverted Hierarchy Sin 2 (2θ 13 ) Sin 2 (2θ 13 ) Como Oct 09 26

27 Measurement of sin 2 (2θ 23 ) Excellent δ(e) in ν µ CC events key, NOνA s δ(e) 2% If sin 2 (2θ 23 ) = 1, δ(sin 2 (2θ 23 )) 0.003, Otherwise, δ(sin 2 (2θ 23 )) 0.02, Como Oct 09 27

28 Sensitivity to CP Phase δ Favorable scenario: δ = 3π/2 normal hierarchy Oscillation at starred pt * CP δ constrained: π δ 2π Como Oct 09 28

29 Current Timeline o Near Detector data taking mid-2010 (surface running) o Near Detector underground Fall 2012 o Far Detector construction o Data taking starts Jan-2012 (partial FD) o Full far detector operational May-2013 Como Oct 09 29

30 Summary o NOνA is a next generation long-baseline ν experiment o Order-of-magnitude gain in sensitivity to sin 2 2θ 13 o Sensitive to mass hierarchy and CP violation o Yield highly precise m 2 23 & sin 2 2θ 23 o Far detector site construction started o Far detector complete & operational in 2013 o Near detector data taking mid-2010 Como Oct 09 30