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Magnetised Iron Neutrino Detector (MIND) at a Neutrino Factory

This presentation discusses the MIND detector and its role in solving degeneracies and determining unknown oscillation parameters in neutrino physics. The analysis methods and recent developments in MIND are also presented.

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Magnetised Iron Neutrino Detector (MIND) at a Neutrino Factory

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  1. Magnetised Iron Neutrino Detector (MIND) at a Neutrino Factory Neutrino GDR Meeting, Paris, 29 April 2010 Paul Soler*, Anselmo Cervera, Andrew Laing, Justo Martín-Albo

  2. Neutrino mixing • Weak eigenstates do not have to coincide with mass eigenstates Ignoring Majorana phases a1 and a2, the neutrino mixing matrix (Pontecorvo- Maki-Nakagawa-Sakata, PMNS matrix) is similar to CKM matrix for quarks. States: where and Neutrino GDR Meeting Paris, 29 April 2010

  3. where is for Neutrino oscillations • Matter oscillation results for three neutrinos: (MSW effect) Minakata & Nunokawa JHEP 2001 Neutrino GDR Meeting Paris, 29 April 2010

  4. where is for Neutrino oscillations • Matter oscillation results for three neutrinos: Only one term in equation (MSW effect) Magic baseline: Clean determination of q13 However, there are up to 8 degeneracies and correlations between variables that need to be determined. Strategy: different experiments at different baselines and energies to solve degeneracies Neutrino GDR Meeting Paris, 29 April 2010

  5. Unknown parameters • Consistent picture emerging • Global fit provides: • sin2q12=0.320.23 • Dm122 =7.60.20×10-5 eV2 • sin2q23=0.500.063 • Dm232=2.40.15×10-3 eV2 Schwetz • Unknown quantities: • sinq13<0.224 (@3s), • Mass hierarchy: sign Dm132 • CP violation phase d Normal Inverted Neutrino GDR Meeting Paris, 29 April 2010

  6. International Scoping Study • The International Scoping Study looked at the physics, accelerator and detector prospects for future neutrino oscillation facilities to determine remaining unknown oscillation parameters • Outcomes have been published as three reports: • Physics report: arXiv:0710.4947, Rept.Prog.Phys.72:106201,2009 • Detector report: arXiv:0710.4129,JINST 4:T05001,2009 • Accelerator report: arXiv:0802.4023, JINST 4:P07001,2009 • Baseline detector requirements from International Scoping Study • Two detectors at 4000 km and 7500 km to solve degeneracies • For a Neutrino Factory facility: • Magnetised Iron Neutrino Detector (MIND) of 50-100 kton fiducial for nm appearance channel (gold channel) at each baseline • Studies are being continued in the context of the International Design Study for a Neutrino Factory (IDS-NF) and EuroNu Neutrino GDR Meeting Paris, 29 April 2010

  7. 0 5 10 15 20 25 Neutrino Energy (GeV) Neutrino Factory • Baseline design for a Neutrino Factory: two different detectors at two different baselines (~4000km, 7500km) 25 GeV muons Neutrino GDR Meeting Paris, 29 April 2010

  8. detector 50-100 m 50% 15 m wrong sign muon n beam 50% 50-100kT 15 m B=1 T iron (3 cm) + scintillators (2cm) 5-10 × Magnetised Iron Neutrino Detector (MIND) • Golden channel signature: “wrong-sign” muons in magnetised calorimeter Magnetic Iron Neutrino Detector (MIND) (Cervera et al. 2000) • Far detector (2000-7600 km) can search for “wrong-sign” muons in appearance mode Neutrino GDR Meeting Paris, 29 April 2010

  9. History of MIND analysis • “Golden” paper (Cervera et al, 2000) was optimised for a small value of q13, so efficiency at low energy cut severely • Used fast simulations and detector parameterisation • MIND analysis redone for ISS (Cervera 2006) – JINST 4 T05001(2009) • Improved event selection, • Fast simulation • Perfect pattern recognition • Parameterisation based reconstruction • 1T dipole field instead of toroidal field • Fully contained muons by range • Scraping muons by curvature • Hadron shower: International Scoping Study (ISS) Neutrino GDR Meeting Paris, 29 April 2010

  10. MIND analysis with full reconstruction • New analysis: arXiV:1004.0358 • Full reconstruction with Kalman filter • Full pattern recognition for muon selection • More than five planes with only one hit – muon • If less than five planes contain one hit: Cellular Automaton • GEANT3 (LEPTO DIS) • Analysis chain using likelihood functions • Still dipole field and hadron shower smearing Muon purity Cellular Automaton Muon purity Kalman filter Neutrino GDR Meeting Paris, 29 April 2010

  11. MIND analysis with full reconstruction • New analysis: arXiV:1004.0358 • Muon curvature extraction through PDF and log-likelihood ratio Muon curvature error PDF Log-likelihood ratio Neutrino GDR Meeting Paris, 29 April 2010

  12. MIND analysis with full reconstruction • New analysis: arXiV:1004.0358 • Likelihood functions for “wrong-sign” muon selection Vis energy fraction < 1 Vis energy fraction ~ 1 Neutrino GDR Meeting Paris, 29 April 2010

  13. MIND analysis with full reconstruction • New analysis: arXiV:1004.0358 • Momentum and isolation cuts Neutrino GDR Meeting Paris, 29 April 2010

  14. MIND analysis with full reconstruction • New analysis: arXiV:1004.0358 • Results after analysis: improvement from ISS result Charge mis-ID NC background Also: ne background ~ 4x10-5 Neutrino GDR Meeting Paris, 29 April 2010

  15. MIND: new developments • Improvements MIND analysis with full GEANT4 simulation • Add quasi-elastics and resonance production (NUANCE): Non DIS processes dominate at low energies and should improve efficiency at low energies Benchmark of NUANCE with data Neutrino GDR Meeting Paris, 29 April 2010

  16. MIND: new developments • Example of GEANT4 event: • Smearing of hits according to hadronic energy resolution • Digitisation of hits into voxels of correct spatial resolution (~1cm) Example of G4 nm-CC event Neutrino GDR Meeting Paris, 29 April 2010

  17. MIND: new developments • Crude digitisation model and clustering algorithm • Use boxes to represent view of matched x,y readout planes with the x,y,z at the centre of a box. • Clustering of adjacent boxes around the largest signal with weighted mean for x,y position. Neutrino GDR Meeting Paris, 29 April 2010

  18. nm-CC nm-CC MIND: curvature error • Curvature error PDF and likelihood function • Wrong-sign muon still a good separator signal-background Neutrino GDR Meeting Paris, 29 April 2010

  19. MIND: likelihood analysis • Likelihoods: number hits in candidate, fraction visible energy, mean energy deposit per plane Preliminary NC CC • Likelihood functions motivated by the MINOS analysis • First analysis based initially only on the number of hits in candidate • Will look at ways of including other variables in the future Neutrino GDR Meeting Paris, 29 April 2010

  20. nm-CC nm-CC MIND: likelihood analysis • First analysis: log-likelihood function exclusively from the number of hits in the candidate • Black, blue: signal; other colours background If num hits > 150 then signal Preliminary Neutrino GDR Meeting Paris, 29 April 2010

  21. MIND: kinematic cuts • Neutrino energy: En=Em+Ehad • Cuts above 7 GeV MINOS CalDet Monolith Preliminary • Fiducial cut: vertex 2 m from end of detector (only 0.2% effect) Neutrino GDR Meeting Paris, 29 April 2010

  22. MIND: kinematic cuts • Summary of all cuts: • sp/p log likelihood ratio > -0.5 • Likelihood on number of hits: • If num hits > 150 then select as signal • If num hits < 150 then log likelihood ratio on num hits > 1.0 • If Erec > 7 GeV then: pm ≥ 0.3Erec and Qt > 0.3 • Then fit muon candidate with a parabola: to remove final events with either very straight muons or muons that confuse the fitter • If num. hits < 50: require candidate muon bends • If charge flips after parabola fit and error in a3 “low” then kill event • Fiducial cut: remove candidates with vertex 2 m from end Neutrino GDR Meeting Paris, 29 April 2010

  23. MIND: likelihood analysis • nm Charged current background Preliminary Background to m- appearance Background to m+ appearance Neutrino GDR Meeting Paris, 29 April 2010

  24. MIND: likelihood analysis • Neutral current background Preliminary Background to m- appearance Background to m+ appearance Neutrino GDR Meeting Paris, 29 April 2010

  25. MIND: likelihood analysis • ne Charged current background Preliminary Background to m- appearance Background to m+ appearance Neutrino GDR Meeting Paris, 29 April 2010

  26. MIND: likelihood analysis • Signal efficiencies: Preliminary Identification efficiency m- Identification efficiency m+ Efficiency better for anti-neutrino channel: needs to be understood in detail but probably due to y distribution – m+ events cleaner due to smaller Ehad Neutrino GDR Meeting Paris, 29 April 2010

  27. nm-CC nm-CC nm-CC nm-CC Improvements: alternate likelihood analysis • We are working on a way to improve the analysis by using more likelihood information from the PDFs Preliminary • Multiplication of three PDFs when fraction visible energy < 1 • Multiplication P1xP3 when fraction visible energy = 1 • Need to optimise likelihood function selections to maximise efficiency Neutrino GDR Meeting Paris, 29 April 2010

  28. Sensitivity MIND at Neutrino Factory • Best sensitivity/cost with 100 kton at 4000 km and 50 kton at 7500 km Winter Neutrino GDR Meeting Paris, 29 April 2010 However, minimising systematics should be one of the main goals!!

  29. Future directions • Add toroidal field Preliminary field map from ANSYS simulation (Bob Sands, FNAL) 0.6 T – 2.2 T with 92 kA-turn Neutrino GDR Meeting Paris, 29 April 2010

  30. Future directions • Add toroidal field In MINOS, had 30 cm aluminium coil with 25 kA-turn With a Superconducting Transmission Line (STL) could achieve 100 kA-turn with one turn! – only would need 10 cm hole Idea by A. Bross (FNAL) • R&D has already been carried out for VLHC!! Neutrino GDR Meeting Paris, 29 April 2010

  31. Future directions • Analysis and simulations: • Improve digitisation • Add toroidal field • Move to GENIE for neutrino interactions • Improve hadronic reconstruction • Add nt signal to oscillation signal • Final sensitivity plots and systematic errors • R&D effort: • Prototype detectors with SiPM and extruded scintillator • Measure charge mis-ID rate • Develop CERN test beam for neutrino detector R&D – European AIDA proposal to make H8 into low E beam Neutrino GDR Meeting Paris, 29 April 2010

  32. Conclusions • Golden channel (wrong sign muon) has the best statistical power for discovering CP violations in neutrinos – other channels have small contribution to standard oscillation physics • Two Magnetised Iron Neutrino Detectors (MIND) at 4000 km with100 kton mass and 7500 km (magic baseline) with 50 kton at standard neutrino factory (25 GeV) gives best q13-dCP coverage performance, especially for small values of q13 • Future developments in the simulation and analysis include improving digitisation,clustering, hadronic reconstruction, implementation of a toroidal field and geometry optimisation • While all the technological concepts are feasible, R&D would also be needed to realise some of the concepts and to benchmark simulations Neutrino GDR Meeting Paris, 29 April 2010

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