Opportunities and Status: Long-Baseline Neutrino Experiment in the - PowerPoint PPT Presentation

Opportunities and Status: Long-Baseline Neutrino Experiment in the US Milind Diwan Exploring the Neutrino Sky and Fundamental Particle Physics on the Megaton Scale” 20 – 23 January 2013 Wilhelm and Else Heraeus Seminar Tuesday, January 22, 13

Outline • Neutrino properties summary. What do we know and what do we want to measure ? • Why a new accelerator Long-Baseline experiment ? How much flux, energy, event rate can we get ? What limitations ? • Strategies for the detector. What are the key differences between a water detector and a tracking calorimeter ? • What is the full physics agenda ? • Technical information for a liquid argon TPC. • Description and Status of LBNE (US) design. Tuesday, January 22, 13

Why Neutrinos ? Pontecorvo 1981 3 Tuesday, January 22, 13

Daya Bay θ 13 Results Sometimes nature is kind ! Observe electron-antineutrino disappearance six 2.9 GWth reactors six 20-ton detectors: 3 near (~500m), 3 far (~1650m) 139 days of running sin 2 2θ 13 =0.089+-­‑0.010(stat)+-­‑0.005(syst) antineutrino detectors far near 4 Rate only. Normalization floating Tuesday, January 22, 13

S. Parke 5 Tuesday, January 22, 13

Best fit to all data. If viewed as a collection of parameters with 3- generations, we need to measure mass ordering, CP phase, ϴ 23 octant. Parameters are such that a practical accelerator based experiment is possible to see 3 generation mixing ! 6 Tuesday, January 22, 13

Connections to more fundamental issues Credibility of leptogenesis Impacts GUT models Observability of double beta decay, and the problem of generations. 7 Tuesday, January 22, 13

The full picture of the oscillation effect Probability for oscillation at 1 GeV ν µ 1 Probability Dashed white lines ν μ 0.9 ν τ correspond to CP 0.8 ν τ violation 0.7 0.6 0.5 It is best to do this 0.4 experiment with a pure 0.3 ν μ broad band beam 0.2 ν e 0.1 0 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Brett Viren Baseline (km) • The neutrino oscillation model is based on limited dataset • With very precise predictions: • Large Matter Effects (not yet seen in a laboratory experiment) • Potentially large CP violation (not yet seen) • We should measure this picture with a detailed spectrum 8 Tuesday, January 22, 13

Optimum ? L/E = 515 km/GeV sin 2 2θ 13 =0.1 Mary Bishai 9 Tuesday, January 22, 13

Although the conventional beam has a small contamination. The expected signal is now much larger than the contamination because of sin 2 2θ 13 ~0.09 10 Tuesday, January 22, 13

Making a neutrino beam. Example from NUMI at FNAL Neutrino ¡mode Horns ¡focus ¡ π + , ¡ K + Events ν μ : ¡ 91.7% ¡ ν μ : ¡ 7.0% ν e +ν e ¡ : ¡ 1.3% Source ¡size ¡makes ¡near ¡and ¡far ¡different Focusing Horns Target 2 ¡m π - ν µ 120 GeV p ’s ν µ π + from MI 15 m 30 m 675 m 11 Tuesday, January 22, 13

Making an anti-neutrino beam: NUMI at FNAL AnB-­‑neutrino ¡Mode Neutrino ¡mode Horns ¡focus ¡ π -­‑ , ¡ K -­‑ ¡ Horns ¡focus ¡ π + , ¡ K + enhancing ¡the ν μ ¡ flux Events Events ν μ : ¡ 91.7% ¡ ν μ : ¡ 39.9% ¡ ν μ : ¡ 7.0% ν μ : ¡ 58.1% ν e +ν e ¡ : ¡ 1.3% ν e +ν e ¡ : ¡ 2.0% Focusing Horns Target π + 2 ¡m ν µ 120 GeV p ’s from ν µ π - MI 15 m 30 m 675 m 12 Tuesday, January 22, 13

Oscillation and Beam Spectrum. As designed for LBNE Neutrino Anti-Neutrino CC Events/GeV/ 0.20 0.20 10000 4000 100kT/MW-yr Probability 8000 0.15 0.15 3000 6000 0.10 0.10 2000 4000 0.05 0.05 1000 2000 0.00 0.00 0 0 0.5 1.0 2.0 5.0 0.5 1.0 2.0 5.0 E/GeV E/GeV θ 13 = 9 o , δ CP r:+90, b: 0, g: -90, dashed: Inverted Hierarchy, L: 1300 km • With 700 kW of 120 GeV protons from the Main Injector, we have designed a beam optimized for the 0.5 to 5 GeV. (yr=2 10 7 sec) • The baseline and energy allows us to measure the spectral distortion and disentangle MH from CPV. • Measure asymmetries of event rates versus energy for both polarities. 13 Tuesday, January 22, 13

Beam Constraints Beam must be designed with many constraints that affect the configuration of the experiment. Beam must be broad band (on-axis) to measure the spectrum. • For fixed L/E the neutrino flux per pion in the forward direction is 0 . 42 E π independent of distance since the E ν ≈ (1 + γ 2 θ 2 ) 1/L 2 is compensated by the solid angle factor. • It is difficult to overcome the solid dN angle factor by the pion yield at low ∝ γ 2 /L 2 energies. d Ω lab • Highest available beam power is at 120 GeV because the current is limited by the booster in 1300 km is a good the current scheme at FNAL. • The beam costs rise fast with primary beam compromise bending angle and the near detector depth. 14 Tuesday, January 22, 13

Cross sections • Given the choice of beam and distance two different visions for the detector are possible: • Use all charged current events and identify each one and measure the total energy of each one. This requires a high granularity detector that can handle multiple tracks. But it can be smaller since using all cross section. A LAr detector is a natural candidate. • Or use primarily the simplest topology events that can be reconstructed and measured. This leads to a detector that can measure single leptons well, but has limited track reconstruction. The detector must be large. WCD is a natural candidate. 15 Tuesday, January 22, 13

Total event rate Neutrino eutrino beam Anti-neutrino neutrino beam 200 kTon 34 kTon 200 kTon 34 kTon Event type WCD LAD WCD LAD 35000 5900 4200 720 CC ν μ (11200) (1900) (2400) (410) CC ν e (beam 260 44 38 6 only) 1400 240 13000 2200 CC ν μ (770) (130) (4000) (675) CC ν e 10 2 90 15 Efficiency for 10-20 % 70-90% 10-20% 70-90% useful events • For 0.7 MW per yr. Detector mass above is fiducial mass. • Total charged current event rate with no selection cuts and no oscillation. (with oscillations in brackets) 16 Tuesday, January 22, 13

Detector Strategies 200 kTon Water 34 kTon Liquid Cherenkov argon • Very high resolution detector should • Use a crude detector, but only allow use of much higher fraction of select well identified single cross section including multi-track electron events(QE) to keep events. background low and energy • Energy resolution might need resolution high. attention if using all cross section. • Known, successful technology • Could use the fine resolution and with wide dynamic range (5 below Cher threshold for MeV-50GeV). background tagging. • Can perform both p-decay, • Could do the specialized proton decay searches very well. Sensitive astrophysical sources, to supernova nues (not anti-nue). • Can be deployed deep scaled • Dynamic range for physics is less up: 50kT to fewX100kTon. well-known. • Will have low efficiency and • Scale up factor needs to be need very large mass. substantial ~100. Tuesday, January 22, 13

Long-Baseline Neutrino Experiment in US 34 kton of LAR 0.7 MW For LBNE the detector selection was extremely difficult. LAr choice was driven by scientific, technological considerations. 18 Tuesday, January 22, 13

Parameter Range of Values Value Used for LBNE Sensitivities For ν e CC appearance studies ν e CC e ffi ciency 70-95% 80% ν µ NC mis-identification rate 0.4-2.0% 1% ν µ CC mis-identification rate 0.5-2.0% 1% Other background 0% 0% Signal normalization error 1-5% 1% Background normalization error 2-10% 5% For ν µ CC disappearance studies ν µ CC e ffi ciency 80-95% 85% ν µ NC mis-identification rate 0.5-10% 0.5% Other background 0% 0% Signal normalization error 1-5% 5% Background normalization error 2-10% 10% For ν NC disappearance studies ν NC e ffi ciency 70-95% 90% ν µ CC mis-identification rate 2-10% 10% ∗ ν e CC mis-identification rate 1-10% 10% ∗ Other background 0% 0% Signal normalization error 1-5% Background normalization error 2-10% Neutrino energy resolutions Ò Ò ν e CC energy resolution 15% / E ( GeV ) 15% / E ( GeV ) Ò Ò ν µ CC energy resolution 20% / E ( GeV ) 20% / E ( GeV ) E ν e scale uncertainty E ν µ scale uncertainty 1-5% 2% [LABEL: “ tab:lar-nuosc-totaltable ”] Detector performance parameters for LBNE 19 LBNE CD-1 Director's Review - 26-30 March 2012 Tuesday, January 22, 13