Accelerator Neutrino Physics I: Present Decade
CHRIS WALTER, DUKE UNIVERSITY
TAUP 2013 September 12th 2013 September 2013: Where do we stand?
Large Θ13! Can we measure CP viola on?
• The measurement of non-zero θ13 has changed the nature of discussions and presenta ons about the current experiments. • I’ll go over some experimental issues related to the accelerator experiments and try to teach you how to compare the experimental results. • Emphasis on long-baseline: T2K, MINOS, OPERA • I’ll try to explore what can we expect to know before the next genera on of experiments starts.
09/12/13 Chris Walter - TAUP 2013 2 OSCILLATION EXPERIMENTS
How do νs oscillate? “Flavor” states are mixture of mass states.
⇥ cos sin ⇥ ⌫µ = ⌫2 cos ✓ + ⌫3 sin ✓ µ = 2 ⌫ = ⌫ sin ✓ + ⌫ cos ✓ ⇥ sin cos ⇥3 ⌧ 2 3 ⇥ ⇥ ⇥ ⌫ (t) = eiE2t ⌫ (0) cos ✓ + eiE3t ⌫ (0) sin ✓ | µ i | 2 i | 3 i 1.27 m2L P = sin2 2 sin2 µ E
Reactor+ Beam Atmos Oscilla ons unknown Solar Oscilla ons
c23 = cos ✓23 s23 =sin✓23
09/12/13 Chris Walter - TAUP 2013 3 Ques ons to answer
• What is the pa ern of neutrino masses? • Is there CP viola on in the neutrino sector? Is it big enough to drive lepto- genesis and is it related to the quark sector?
“Normal” “Inverted”
In a beam experiment, the signal for non-zero
θ13 is νe appearance in a pure νµ beam.
There are differences in the rate of appearance between neutrinos and anti-neutrinos if there is CP violation and also for the different hierarchies in matter.
09/12/13 Chris Walter - TAUP 2013 4 How do you build a long-baseline experiment? (1st example: K2K -> MINOS -> T2K -> Nova)
GPS Satellite (broadcasts time) Proton Synchrotron
Protons
Neutrinos Pions Decay Pipe Magnetic Horns Near detectors
Always the same pattern: Accelerator -> Target -> Horns -> Decay Pipe -> Near detector -> Far Detector 09/12/13 Chris Walter - TAUP 2013 5 On and Off-Axis Beams Super-Kamiokande Neutrino Source Off Axis (2.5°) off-axis Proton Beam ° on-axis Neutrino Beam π 2.5 monitor =
Θ 0m 120m 280m 295 km
400 The kinema cs of pion decay allow at 295 km 350 us to make a narrower neutrino Peak flux is higher beam. All 300 2º and energy band is narrower. 250 200 (GeV) ν
E 150 High Energy 100 tail causes Backgrounds 50
0 0 1 2 3 4 5
Epion (GeV) En (GeV) 09/12/13 Chris Walter - TAUP 2013 6 Oscillation searches at accelerators There are two types of searches: Appearance and Disappearance
• Appearance: MiniBoone, T2K, Nova, • Disapearance: MINOS, K2K, SK OPERA
disappearance: νe appearance: νµ determine θ and Δm2 determine θ13 23 23
Enough energy to produce lepton in NOT enough energy to produce CC reaction. lepton in CC reaction.
09/12/13 Chris Walter - TAUP 2013 7 How do we measure θ13? 2 2 2 2 Δm23L P(νµ →νe ) = sin θ23 sin 2θ13 sin + sub-leading terms 4Eν (sinδ is in here)
Schematic figure νe appearance is crucial for studying the MH and CPV!
Measure the electron appearance probability on top of a background
For appearance three main types of background: 0 intrinsic νe , misidentified π , mis-identified charged µ We need a very high intensity beam and a large target. Make a pure neutrino beam and look for electrons to appear.
09/12/13 Chris Walter - TAUP 2013 8 The T2K Experiment Super-K water Cherenkov Detector as far detector. Uses the JPARC accelerator complex 295 km away
Far detector: Super-K On and off-axis hybrid near detectors
ν eCC BG NC
‣ 50 Kton Water Cherenkov Detector ‣ >11,000 PMTs read out by QTCs ‣ Image processing for reconstruction
09/12/13 Chris Walter - TAUP 2013 9 T2K observa on of νe Appearance
normal hierarchy
Inverted hierarchy
4.6 events expected background 28 events observed 20.4 ± 0.8 events expected @ sin22θ = 0.1
7.5σ significance for non-zero θ13 First ever observation (>5σ) of an explicit ν appearance channel
09/12/13 Chris Walter - TAUP 2013 10 Let’s think about these regions!
09/12/13 Chris Walter - TAUP 2013 11 T2K νμ Results (Run I-III)
Maximal mixing is not the same as maximum Shows the power of the off-axis technique! disappearance if θ13 is not zero!
205 +- 17 events expected (no oscillation)
2 2 2 sin 2θ23 Δm32 χ / ndf Nobs Nexp
θ23 ≤ π/4 1.000 2.44e-3 56.04 / 71 57.97 58 θ23 ≥ π/4 0.999 2.44e-3 56.03 / 71 57.92
09/12/13 Chris Walter - TAUP 2013 12 T. Vahle (W&M) New MINOS Results
Updated results: 735 km 10.7 x 1020 pot neutrino 3.4 x 1020 pot anti-neutrino Near 1 kton Far 5.4 kton 37.9 kton-years atmospheric
Appearance: Disappearance Atmospheric Use sta s cal separa on based on a pa ern matching library
Combine Beam and Atmospheric data:
09/12/13 Chris Walter - TAUP 2013 13 T. Vahle (W&M) PUTTING IT ALL TOGETHER
¢ Solar mixing parameters fixed
¢ θ13 fit as nuisance parameter, constrained by reactor results
- TAUP 2013TAUP - 2 ¢ �CP , θ23, Δm unconstrained
Vahle ¢ major systematic uncertainties included as nuisance parameters 14 T T. Vahle (W&M) MINOS CPδ Dependence Appearance Only Appearance+Disappearance
09/12/13 Chris Walter - TAUP 2013 15 Let’s compare experiments!
09/12/13 Chris Walter - TAUP 2013 16 T. Vahle (W&M) MINOS+ is coming….
Simulated ν Beam • MINOS will con nue to run in 5.4 kton, 6 × 1020 POT the NOvA era 1000 • ME beam peaks above the MINOS+ oscilla on dip on axis NOvA • But they get a lot of events! MINOS – ~4000 muon neutrino CC 500 events per year expected at Preliminary FD CC Events / GeV
µ • Unique test of oscilla on ν paradigm with sensi vity to 0 0 5 10 15 20 exo c signals
Eν (GeV)
09/12/13 Chris Walter - TAUP 2013 17 D. Duchesneau (Annecy LAPP) OPERA tau appearance experiment
Uses ECC (Emulsion Cloud Chamber) Electronic trackers point With automatic scanning Back to bricks. + Magnetic spectrometer. Ran from 2008 - 2012
3 observed events in the τ è h, τ è 3h and τ è µ channels This corresponds to 3.2 σ significance of non- null observation (3.5 σ significance with a likelihood approach) Signal
(also reported on nue search) 09/12/13 Chris Walter - TAUP 2013 18 Noνa – Low Z calorimeter • 14 kton “totally ac ve” liquid scin llator detector Low Z tracking calorimeter: tracking + allow me for photons to convert and showers to develop. Low Z calorimeter (near and far detectors) No B field.
Nova is unique in current genera on of experiments for addressing mass hierarchy using neutrino and an -neutrino beams.
νeCC BG NC
09/12/13 Chris Walter - TAUP 2013 19 Uses an upgraded version of the current NuMi beam The NuMi beam will be upgraded from 300 -> 700 kw.
One of the largest devices ever constructed from plas c. There has been an impressive amount of R&D.
Beam turned on last week!
09/12/13 Chris Walter - TAUP 2013 20 Detector Status Cosmic Rays! Cosmic
• Far detector completed ~May 2014 • First half near detector ready early 2014
09/12/13 Chris Walter - TAUP 2013 21 NO A CPV determination, 3+3 yr Expected Nova sin22 =0.095, sin22 =1.00 13 23 2.5
) 2 m <0 Sensi vity 2 m2>0
1.5
1
0.5 significance of CP violation ( violation CP of significance
0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 /
NO A hierarchy resolution, 3+3 yr sin22 =0.095, sin22 =1.00 ) 13 23
3.5
2 3 m <0 m2>0 2.5
2
1.5
1
0.5
significance of hierarchy resolution ( 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 / 09/12/13 Chris Walter - TAUP 2013 22 Expected T2K Allowed Regions “Lucky! (δCP=-90)”
100% ν (true NH) 50% ν/50% an -ν (true NH)
100% ν (true NH) 50% ν/50% an -ν (true NH) w/ Reactor constraint w/ Reactor constraint
09/12/13 Chris Walter - TAUP 2013 23 Expected T2K Allowed Regions “Unlucky! (δCP=0)”
100% ν (true NH) 50% ν/50% an -ν (true NH)
100% ν (true NH) 50% ν/50% an -ν (true NH) w/ Reactor constraint w/ Reactor constraint
09/12/13 Chris Walter - TAUP 2013 24 MH using T2K and Nova NO A hierarchy resolution, 3+3 yr NO A hierarchy resolution, 3+3 yr 2 2 sin22 =0.095, sin22 =1.00 21 sin 2 =0.095, sin 2 =1.00 ) 13 23 + T2K at 5.5×10 POT ) 13 23
3.5
3.5
2 2 3 m <0 3 m <0 2 m2>0 m >0 2.5 2.5
2 2
1.5 1.5
1 1
0.5 0.5
significance of hierarchy resolution ( 0 significance of hierarchy resolution ( 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 / / NO A hierarchy resolution, 3+3 yr NO A hierarchy resolution, 3+3 yr 2 2 2 2 21 sin 2 13=0.095, sin 2 23=1.00 sin 2 13=0.095, sin 2 23=1.00 + T2K at 5.5×10 POT 1 1 0.9 0.9 0.8 0.8 m2<0 m2<0 0.7 0.7 m2>0 m2>0 0.6 0.6 0.5 0.5 0.4 0.4 Fraction of Fraction of 0.3 0.3
0.2 0.2 0.1 Nova only 0.1 Nova + T2K 0 0 0 0.5 1 1.5 2 2.5 3 3.5 0 0.5 1 1.5 2 2.5 3 3.5 Significance of hierarchy resolution ( ) Significance of hierarchy resolution ( ) 09/12/13 Chris Walter - TAUP 2013 25 CPV using T2K and Nova NO A CPV determination, 3+3 yr 2 2 sin 2 13=0.095, sin 2 23=1.00 T2K only 50% ν/50% an -ν 2.5
) 2 m <0 Nova Only 2 2 STAT ONLY m >0
1.5
1
0.5 significance of CP violation ( violation CP of significance
0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 /
NO A CPV determination, 3+3 yr 2 2 21 2012 systematics sin 2 13=0.095, sin 2 23=1.00 + T2K at 5.5×10 POT 2.5
) 2 m <0 2 m2>0
1.5
1
0.5
significance of CP violation ( violation CP of significance Nova + T2K 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 / 09/12/13 Chris Walter - TAUP 2013 26 Accelerator Neutrino Physics II: Long-term vision
09/12/13 Chris Walter - TAUP 2013 27 Our Strategy
Since we have measured θ13 we need to (with high accuracy): – Measure the phase of δ and hopefully observe CP viola on – Determine the mass hierarchy [if not already done] – Make precision measurements of the mixing angles.
To do this we need to both increase the intensity of our Super-beam sources, and increase the mass of our detectors.
Now or Soon Glorious Future J-PARC 0.75 MW (T2K) JPARC-II to Hyper-K FNAL (Numi) 0.70 MW (Nova) New beam -> LBNE
Water Cherenkov 22.5 kton (SK) 560 kton Fine Grained 14 kton (NOνA) 34 kton (LAr)
09/12/13 Chris Walter - TAUP 2013 28 http://arxiv.org/abs/1307.7335 The LBNE Experiment
1300 km
A new neutrino beam at Fermilab 700 kW, 60-120 GeV proton beam, 2.3 MW capable A near neutrino detector A 1300 km baseline: Fermilab-SURF A 34 kt Liquid Argon TPC with 4850’ overburden
09/12/13 Chris Walter - TAUP 2013 29 The LBNE detector and scoping 34 kton liquid Argon TPC two 17 kton TPCs Located underground at SURF
Current situation:
The experiment is funded for a 10 kton far detector on the surface.
In discussion with international partners to make the detector bigger and put it underground along with adding a near detector complex.
09/12/13 Chris Walter - TAUP 2013 30 LBNE 10kt Sensi vity
2 Bands: 1σ varia ons of θ13, θ23, Δm31 (Fogli et al. arXiv:1205.5254v3) T2K 750 kW x 5 yr (7.8x1021pot) ν NOνA 700 kW x (3 yr ν + 3 yr ν) (3.8 x1021pot) LBNE10 (80 GeV*) 700 kW x (5 yr ν + 5 yr ν) *Improved over CDR 2012 120 GeV MI proton beam 09/12/13 Chris Walter - TAUP 2013 31 A. Rubbia(ETHZ) The LBNO Experiment
Laguna was EU FP program to design a unifica on and neutrino astrophysics program in Europe. Several sites and detectors technologies were considered and the LBNO program was one of the products of the process.
09/12/13 Chris Walter - TAUP 2013 32 A. Rubbia(ETHZ) Glacier
A different approach: LNG tank based detectors.
09/12/13 Chris Walter - TAUP 2013 33 A. Rubbia(ETHZ)
09/12/13 Chris Walter - TAUP 2013 34 http://arxiv.org/abs/1109.3262v1 The Hyper-Kamiokande Experiment
• 560 kton fiducial mass • 99000 PMTs 20% coverage • Outer veto detector
• Sensi vity studies scale SK result to large exposure, i.e. assume the same detector performance
Uses an upgraded JPARC beam Sent to Hyper-K 1 Mton water Cherenkov detector in Kamioka
09/12/13 Chris Walter - TAUP 2013 35 Hyper-Kamiokande Sensi vity
Note: In HK atmospheric neutrinos can be used to constrain MH.
09/12/13 Chris Walter - TAUP 2013 36 Measuring zero δCP is not a failure!
09/12/13 Chris Walter - TAUP 2013 37 Long term reach / other op ons
M. Toups (MIT)
nuStorm: P. Huber, Snowmass Muon Storage ring 2013 experiment gets electron and muon neutrinos with a enormous flux.
09/12/13 Chris Walter - TAUP 2013 38 Conclusion
2 sin 2θ13 is now known to be non-zero! Accelerator experiments have measured an appearance signal. Values will get even more precise.
Now we can check the full consistency of our models using accelerators, atmospheric neutrinos and reactors. Let’s keep working hard, and and try to measure CPV!
09/12/13 Chris Walter - TAUP 2013 39