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MINOS and NOvA: Himmel, Howcroft, Mualem, Newman, Ochoa, Orchanian, Patterson, Peck, Trevor

MINOS and NOvA: Himmel, Howcroft, Mualem, Newman, Ochoa, Orchanian, Patterson, Peck, Trevor. Faculty MINOS  e Analysis; Neutral Current Bg. Anti-Neutrino &  -  Oscillation Analysis Beam systematics (  e and  m ) Veto Shield: Precise Calibration NO  A R&D

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MINOS and NOvA: Himmel, Howcroft, Mualem, Newman, Ochoa, Orchanian, Patterson, Peck, Trevor

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  1. MINOS and NOvA:Himmel, Howcroft, Mualem, Newman, Ochoa, Orchanian, Patterson, Peck, Trevor • Faculty • MINOS e Analysis; Neutral Current Bg. • Anti-Neutrino & -Oscillation Analysis • Beam systematics (e and m) • Veto Shield: Precise Calibration • NOA R&D • Megaton Water-Scint. Detector R&D • Newman, Peck • Ochoa, Patterson +undergrad • Himmel, Ochoa, Patterson, Orchanian • Himmel, Ochoa • Ochoa • Trevor, Mualem, Himmel, Patterson • Trevor, Himmel +undergrad

  2. Neutrino Physics at Caltech MINOS Goals Measure nm↔nt flavor oscillations Precise (Now ~5%) measurement of Dm223 Provide high statistics discrimination against alternatives such as decoherence, n decay, sterile neutrinos, etc. Search for subdominant nm↔ne oscillations A shot at measuring q13 (or: improve CHOOZ limit by a good factor of two) Directly compare atmospheric n vs anti-n oscillations: MINOS is the first large underground detector with a magnetic field for m+/m-tagging event-by-event First measurement of charge ratio from cosmic neutrinos. Use beam anti-for oscillation and BSM physics + Reverse Horn Current Running

  3. MINOSMain Injector Neutrino Oscillation Search Investigate n and anti-n flavor oscillations using intense, well-understood NuMI beam Two similar magnetized iron-scintillator calorimeters Near Detector 980 tons, 1 km from target, 90m deep Far Detector 5400 tons, 735 km away, 700 m deep 735 km Veto Shield Far Detector

  4. nμDisappearance m pure nμbeam Monte Carlo Monte Carlo Intense Beam m n n n n n Unoscillated n n proton n p proton Oscillated p • Basic idea is to compare oscillated and unoscillated spectra, using 2 “~identical” Fe-Scint. Tracking Calorimeters Cross Section & Beam uncertainties cancel to high accuracy between the two Detectors

  5. MINOS: Caltech History and Roles HISTORY: MINOS at Caltech • Original Detector Concept and Design; Co-Leadership: Doug Michael • Led Successful Optical Fiber R&D: ~10 p.e. Per M.I.P; Data Quality Key • Half of the scintillator modules were built at Caltech, in Lauritsen Lab ROLES • Howcroft on MINOS Exec. Committee, paper review committees, DAQ software, MC production and Software Review Committee • Central Roles in Atmospheric Neutrino Analysis [CH] • neAnalysis: Shower reco., selection, bgd. calculations [PO,CH,AH,HZ] • CR Veto Shield: Rigorous Geometry, Time-Calibration, Alignment; Operations [Pedro Ochoa; now the MINOS expert] • Proton Intensity R&D [Michael]: Barrier RF Stacking; [HZ]Digital Damping System for the 8 GeV Booster [CH] New Ongoing ROLES • Lead role inneAnalysis (MCNN);nebackgrounds [PO, RP] • Lead role in antineutrino analysis: Dm223, [AH with PO, RP] (CPT Test), beam systematics, other BSM physics (e.g. n – n oscillations) • Half of Simulation Production done on the Caltech Farm [LM]

  6. MINOS Status The last four years have been a very exciting time for MINOS NuMI construction project completed successfully in January 2005 Analyzed ~12kTon-years of Atmospheric, sign-separated data; including before beam; tested charge ratio in neutrino interactions Have been taking physics beam data since March 2005: We have collected 5 x 1020 protons on target MINOS and NUMI have been running well: now getting > 6x1018 (Record 7.4x1018) POT per week Expect to reach 1021 PoT by 2010

  7. MINOS – NUMI RunningNow 5 X 1020 POT Many thanks to Accelerator Division Colleagues!! Accelerator shutdown Accelerator shutdown Data used in the current disappearance result(3.36E20 POTs) Beginning of MI “2+9” multibatch slipstacking:Note steady rise in POTs/Week

  8. MINOS Status: Physics Papers Recently submitted: Detailed Detector paper to NIM New Charged Current Neutrino Oscillations to PRL Sudden Stratospheric Warming to Nature Lorentz Violation in the Neutrino Sector to PRL Papers in final stages of preparation: Neutral Current (Search for sterile neutrinos) Anticipated papers in the next year: Electron Neutrino Appearance Antineutrino Oscillations Other cosmic ray physics (moon shadow, etc.)

  9. Recent Neutrino Results The most recent moscillation results, with 3.36x1020 PoTs, just submitted to PRL: Dm223 = (2.43 ± 0.13) x 10-3 eV2

  10. Physics of Anti-neutrinosUsing MINOS and NUMI • Caltech [CH, PO] formed a study group in 2006 to investigate the physics of anti-neutrino’s using MINOS. • Physics subjects investigated: • Δm223 for anti-neutrinos: CPT violation tests • ννTransitions. • Obtaining a measurement of the intrinsic beamνe an important background for the θ13 analysis. • A great deal of progress in the last year, led by Ochoa, Himmel and Patterson

  11. Antineutrino Reach • Approx. 6% of our beam is made of muon antineutrinos. • MINOS could distinguish between m223 and m223 at 90% C.L. if m223> 0.004 eV2 with currently available data. • But if CPT conserved, we could only set an upper limit on m223 • If neutrinos were transitioning to anti-neutrinos 30% of the time, we would see a 3 σ difference from the no transitions hypothesis. Current combined world upper limit Preliminary MC Preliminary MC

  12. Caltech Roles in Antineutrinos • Caltech has central roles in the antineutrino analysis • Founded the MINOS antineutrino group [CH, PO; AH] • Solely responsible for the → transitions analysis • Primarily responsible for the downstream production systematics– a unique systematic for antineutrinos • Significant support roles for the whole antineutrino analysis – maintain common files and code • Caltech authored a proposal to run in antineutrino-focusing mode (with “reversed horn current”). • Even a relatively modest amount of running in this mode would allow the us to makethe world’s best measurement of antineutrino oscillations.

  13. Antineutrino Systematics • ~30% of antineutrinos produced outside of the target region and create a large fraction of the difference between the response of the near and far detectors. • For safety reasons, helium replaced the Decay Pipe vacuum – selectively enhances Decay Pipe production. • By looking at the change when Helium was added, we can measure the uncertainty for downstream production. • For a more long term solution, we are working on improvements to the beam Monte Carlo. 13

  14. Antineutrino Running • The difficulties summarized above can be overcome with a small amount of reversed horn current running (RHC). • In this case negative particles from the target are focused, thus yielding an antineutrino beam: 1x1020 POT 1x1020 POT Reversed horn current (RHC) Forward horn current (FHC)‏ Peak reduction due primarily to cross-section difference ()‏ Relatively very few antineutrinos in neutrino beam in the region most relevant to oscillations

  15. 2005 global fit (Strumia and Vissani)‏ 90% C.L. with 6 monthsMINOS reversed mode Antineutrino Running • In past year: modernized analysis code, improved cut efficiencies, studied syst. errors, probed world reach • One year MINOS RHC run beats by a factor of two the most optimistic possible2010 world knowledge of Δm2 • A Caltech effort – and now a key part of MINOS 2010+ plan ~6 month run  8X Error Reduction Sensitivity Per Interaction is Similar

  16. ne Appearance • At MINOS’ baseline of 735 km, • MINOS could make the first measurement of a non-zeroq13by looking for neappearance in the Far Detector • If there is no discovery MINOS will improve the current limit set by CHOOZ by a factor of ~two • Main challenge in MINOS is distinguishing between EM and hadronic showers. • Measurement rests on two pillars: • Optimal separation of ne’s from the backgrounds • Precise determination of those backgrounds.

  17. ne Appearance Analysis at Caltech • Critical role played by Caltech group in both of these areas: • Methods to measure the hadronic and intrinsic beam nebackgrounds were developed in previous years (see backup): • Muon removed (“MRCC”) samples are now in wide use throughout the collaboration (not just the ne group). • An estimate of the beam ne rate in the ND detector was obtained from the measured anti-neutrino rate. Beam ne rate = 1.57 ± 0.37(stat) ± 0.41 (syst) times the tuned MC expectation • Over the last year we completed the implementation of a novel ne selection method that exhibits the highest sensitivity to q13 (following slides)

  18. The Monte Carlo Nearest Neighbors (MCNN) Selection [PO, CH] • For analysis need to have an optimal neselection to maximize the significance of the signal, while controlling systematics. • Most available selections use multivariate techniques that rely on reconstructed quantities. • But this analysis is a special case: Number of reco variables ~ number of strips in event • Why not perform event ID using strip information alone? • We have developed a “nearest neighbors” selection in collaboration with Cambridge University. • Basic idea: • Compare each event in the data to large libraries of simulated ne CC and NC events. • Select N best pattern-matches • Construct a discriminant from N best-matches information (e.g. fracCC=fraction of N best matches which are ne CC)

  19. The MCNN Selection • Determine how well two events match by asking: Charge (PE) Strip # “what is probability the two events come from same hit pattern at PMTs?” • Good match Original ne CC event Poisson plane # Bad match • Advantages: • Approach is in principle optimal. No loss of information from raw → reconstructed quantities • Largely reconstruction-free. • Computation-Intensive: Must fully sample phase space for optimal results • A 50 million event library was generated at the Caltech farm. • Much work [PO, RP] has gone into making code as fast as possible. Current version is about 70 times faster than the original !

  20. Performance of the MCNN • A “MCNN pid” is constructed from the 50 best matches information. • The MCNN selection provides ~15% better sensitivity to sin2(2q13) than the next best ne selection (ANN): • MCNN also gives a > twice the signal to background ratio:

  21. Towards a First ne Result • We are working towards a first q13 result with 3.25x1020 POT • Many systematic studies done at Caltech for all selection methods: • Effects of imperfect hadronic shower simulation and cross-talk on the Near-Far extrapolation • Cut optimization and data quality • Example: We used events simulated with a different shower model as fake data, and applied the standard analysis to study the effect on the number of events predicted in the Far Detector Biases (last column) are only ~ a few percent for all methods ! Well within our systematic error estimates • We expect to complete the analysis in ~6 months

  22. Caltech in NOnA • Sensitive to Sin2 2q13 down to ~0.01 (~15X better than the current limit); possibly resolve the mass hierarchy • D. Michael had a founding role; led design & development • CD2 Nearing Completion; Next is CD3A (Start of Construction) • Caltech involvement ramped up successfully in 2005-7;substantially strengthened since 2007 by arrival of Leon Mualem • LM on the Executive Committee, Technical Board, and Level 2 Manager for Electronics & DAQ • Caltech now has the central R&D role, covering the key measurements that set the design & construction: light output, fibers, extrusions, mineral oil[J. Trevor, L. Mualem] • Our experience with MINOS development and fabrication (Trevor, Mualem) is proving to be invaluable • Arrival of Tolman Fellow Patterson in 2007 will substantially strengthen our effort on NOnA, as well as MINOS

  23. The NOnA Detector ~62 m • ~15 kT total mass, off axis • “Totally Active” granular liquid scintillator design • Outstanding ne patternrecognition & measurement 15.4 m 23

  24. NOnA Tasks at Caltech • Hardware • Electronics/DAQ Management • APD Testing • PVC Testing • Fiber Testing • Vertical Slice Tests—Critical Performance measurement for CD3A • Software • Initial Framework Development • Subshower Package Adapted from MINOS • Photon Transport simulation • Supernova Sensitivity • APD/Electronics Response Simulation 0.7mm WLS Fiber One Cell Caltech Initiated or Responsible for Many Key Aspects of NOnA

  25. Vertical Slice Results 25 • Now using prototypeAPD and Front-End Board for readout • Functionally equivalent to final design components • Several months of data taking have yielded excellent results, testing several cells at once • Average light Yield: 35 pe/muonfor 300ppm dye concentration • Expectation was 25pe: • Exceeded expectations

  26. Electronics Response Simulation:Readout Filter Optimization (Toolkit) 26 Input – (black) It includes signals at 50,60, and 150 clock ticks Output – (red) The output of the shaper, determined by rise-time and fall time. This also has Gaussian distributed amplifier noise added. DCSOut – (blue) A simple Dual-Correlated Sample filter picks out signals at 50,60, possibly 150, depending on threshold. Convolution – (Magenta) A more advanced filter; convoluting perfect signal with an interpolated output signal. Useful for precise timing when signals are isolated, but doesn’t resolve double pulses well. Optimal Filter: in ~1 Year

  27. WLS Fibers PMT (A 1 m cube) ADR Grant: Prototyping Next-Generation Megaton-Scale Neutrino Detectors • ADR grant: covered technician salary (part time) and equipment • Focus on further development of water/plastic scintillator systems • Aims: high light output; low cost per kiloton (projected savings: 80 - 90% • Sol’n: 1 cubic meter tank detector  • Scintillator strands replaced granules of earlier design • Easier to get high quality scintillator, no circulation system required • More realistic configuration for larger detectors, but more difficult to construct • Construction complete in mid-2007 Promising preliminary results 1 Meter CubePrototype Scintillator Strands

  28. Successful Initial Results; Oulook This is a promising new technology More R&D is necessary to optimize the design and construction techniques We plan to apply for further ADR funding A paper is in the works • Construction is complete • Initial results showlight that the output is essentially the same as MINOS: 6 pe/cm of scintillator 28

  29. MINOS/NOnA GroupBudget Request Faculty (HN, Peck), Research Scientist (Leon Mualem), Tolman Fellow (Ryan Patterson), 3 Grad. Students (Himmel, Ochoa, Orchanian), Technician (Trevor) • Doug Michael tragically passed away in 2005 • ~$ 130k cut from MINOS Budget in 2007-2008 • Barish and Peck are Emeritus, Zheng and Howcroft left • New in 2007: Research Scientist L. Mualem, Tolman Fellow R. Patterson (50% on Grant), Grad Student M. Orchanian • Although smaller, the group remains strong: Caltech has established crucial, central roles in both MINOS operations and physics, and NOnA R&D and construction • We request the minimum needed: $ 564k for FY2009 on the DOE Grant [This is + $ 27k from FY08; Still ~$ 100k Less than FY06]

  30. MINOS/NOnA Group Payoff MINOS and NOnA Leading Contributions MINOS Antineutrino Oscillation Analysis and RHC Run ne Optimized Analysis for 1  3 Oscillations n - n Transition Analysis CC Analysis for Neutrino 2  3 Oscillations NOnA Key Detector Design and Development Studies Leadership of Electronics and DAQ Vertical Slice Test, Leading in to CD3A Analysis for More Sensitive Tests of 13

  31. Backup Slides on Antineutrinosin MINOS

  32. all NC without fit signif. cut with fit signif. cut The Antineutrino-PID Method [Ochoa] • For each event, calculate the product of probabilities that event comes from the nu or nubar distributions The nubar-PID parameter is given by: • Observe very clear separation: Very high purity with good efficiency Purity Increase NuBar-PID cut Fit significance cut: Efficiency Note: Efficiency measured w.r.t. all true CC antineutrinos

  33. Antineutrino physics • Very interesting physics can be done with antineutrinos: 1)noscillation analysis: A large CPT-violating region still unexplored 90%, 95%, 99% and 3σ CPT violating regions still allowed by global fit (except LSND) M.C. Gonzalez-Garcia, M. Maltoni and T. Schwetz (hep-ph/0306226) 2)n→n transitions: have never been looked for beforein atmos sector. • Some models beyond the SM predict them (i.e. Langacker and Wang, Phys. Rev. D 58 093004). • Could fully explain the atmospheric neutrino results (Alexeyev and Volkova, hep ex/0504282) 3) Measurement ofBeam ne’s: important for ne analysis • Very strong involvement of Caltech group in these areas. 33

  34. 1 0.5 with SK parameters 0 E (GeV) 0 15 30 Antineutrinos in MINOS • Approx. 6% of our beam is made of muon antineutrinos. Amplified spectrum MC 1x1020 POT Difficulty: not many events in osc. peak region Difficulty: not many events in osc. peak region • Unique advantage: both MINOS detectors are magnetized. Allows us toseparate neutrinos and antineutrinos on an event-by-event basis. 34

  35. Beam systematics Old Monte Carlo New Monte Carlo Flugg Geant 4 Geometry Geant 3 Geometry Flugg Fluka Geometry Geant-Fluka Physics Geant 4 Physics Fluka Physics • Working to update the beam Monte Carlo from Geant3 to Geant4. • Use Flugg to run the new geometry in Fluka, a more trusted physics simulation

  36. Rate Comparison, FHC & RHC RHC anti-neutrino andFHC neutrino osc.measurements differ primarily in event rate. 2.9X more events/proton in FHC/ mode (below 6 GeV) • Rate differences come from : (FHC/advantage in parentheses)‏ • N CC cross section (+100%)‏ • n/p ratio in detector (+15%)‏ • π+ versus π- production in the target (+30% near energy peak)‏ • CC efficiency (-5% near energy peak)‏

  37. Reversed Horn Current Mode Sensitivity • Left: FHC/ and RHC/ sensitivities for same exposures (stat only) • Right: Same number of events below 6 GeV (i.e. 2.9 Times more RHC than FHC exposure) • Rate is indeed the primary difference 37

  38. Antineutrino Oscillation World Reach • Red = MINOS reversed-mode oscillation sensitivity • Black = Combined post-FY2010 sensitivity from MINOS atm. (most exposure scaling) MINOS FHC anti-neutrino sample Super-K, with either... Situation assuming SK isalready systematics limited ...current published Super-K ...sqrt(N) Super-K scaling

  39. Backup Slides on MINOS ne Appearance Analysis

  40. Muon Removal Method • Use Muon Removal (MR) to assess the hadronic backgrounds: • Apply muon removal (MR) to both data and MC • Apply ne selection on both. • Use differences in both samples to reweight the NC expectation in the ne analysis. # of ne candidates in MR data # of NC events in ne analysis ND data before MR after MR (NN selected events) # of ne candidates that are NC in MC # of ne candidates in MR MC • MR reweighting removed the ~60% overall normalization discrepancy

  41. Beam ne’s from antineutrinos • Irreducible background in ne analysis: intrinsic beam ne‘s Nearly all come from m+→ e+ + ne + nm • Need to tag antineutrinos coming from m+ decay. Use fact that antineutrino spectrum is practically the same independently of the beam configuration: Most antineutrino parents just go through the center of both horns pseudo-high energy (pHE) pseudo-medium energy (pME) Low energy (LE) MC MC MC • Work led by Caltech, in collaboration with BNL

  42. n from m+ nfromm+ Beam ne’s from antineutrinos • Only m+ component changes significantly when running in pME or pHE ! The Technique: (pME-LE)TRUE at 1e18 POT • Scale pME (or pHE) and LE data to same POT and take the difference • Fit with using shapes from the MC: LE Corrections due to differences in the antineutrinos from p- and K- pME • Preliminary result obtained with 1.6x1019 POT of pHE data: Beam ne rate = 1.57 ± 0.37(stat) ± 0.41 (syst) times the tuned MC expectation

  43. The MCNN PID • A “MCNN PID” is constructed from the best 50 matches information: • 1) fracCC = fraction of best 50 matches that were e CC with y<0.9 • 2) mean frac. Q matched = mean fractional charge matched of ne CC matches with y<0.9 (among first 50) • 3) ymean = mean y of e CC matches with y<0.9 (among first 50) • Using: • Variables are combined by an energy binned likelihood (0.5 GeV bin width): • The MCNN PID in the ND: data/MC

  44. Cut Optimization • The cut optimization of all methods was done at Caltech. • 4 different “Figures of Merit (FOM)” were used and compared: ANN30 MCNN FOM FOM Gaussian-FOM Gaussian-FOM Likelihood-FOM Likelihood-FOM sig/bg sig/bg

  45. Near detector data stability • Caltech investigated the impact of detector drift on the e analysis • e analysis affected little by drifts in light output, etc. • Rate of preselected e candidates shown below ~2% step across shutdown (due to target position) is handled by the systematic errors

  46. Imperfect shower modeling • We know of something for sure the hadronic simulation of showers is imperfect in the MC. • How does the hadronic shower modeling feed into the Far/Near differences? • Took simulation with a different hadronic model as fake data and ran the analysis using the standard MC. MCNN ANN30 ANN6 SS CUTS Obtained biases are only in the order of a few percent for all methods. → Well within our systematic error estimations.

  47. Milestones for the neMeasurement • We managed to use the same FD library of events for the ND: • Use a correction factor obtained from muon tracks to scale the ND light level to match the FD. Charge deposited by muons (after correction) In the ND light is only read out from the west end FD ND • Studies show that the FD background prediction is very insensitive to this correction. • Structured the code so that it can be run at machines with 2GB of memory: • Storing information of 200 best matches for ~60,000 events ! • Processed all files offline at the Caltech farm. • MCNN output is now injected back into the collaboration-wide event samples, for use by the entirenegroup

  48. Backup Slides on NOnA R&D

  49. Overview of Detector R&D NOnA Perform light output tests to understand the components of the scintillator system [Ongoing] PVC extrusions, liquid scintillator, WLS fiber Verification of scintillator system performance using a NOnA APD [Ongoing] Photon production and transport Monte Carlo [Ongoing] Tests and Optimization of the ElectronicReadout [Ongoing] Personnel – Jason Trevor, Leon Mualem + undergraduate

  50. NOnA Scintillator System Each cell an extruded TiO2 loaded PVC tube with ID 60mm x 39mm x 15.7m long Cells are filled with mineral oil scintillator which is read out at one end with a U-loop WLS fiber running to a multi-pixel APD Kuraray 0.7 mm WLS Fiber Light output requirement determined by achievable noise on the APD amplifier.The current estimate of minimum required Light Output is ~20-25 photoelectrons 0.7mm WLS Fiber • R&D at Caltech • Composition of the PVC cell walls • Liquid scintillator composition • Fiber diameter and dye concentration • Fiber position • Integration testing One Cell

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