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Summary Detector Working Group

Discussion on MIND, near detector, simulation, kinematics, charge identification, muon reconstruction, and event generation for a Neutrino Factory. Detailed analysis to optimize sensitivity and efficiency.

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Summary Detector Working Group

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  1. Summary Detector Working Group Neutrino Factory International Design Study Meeting 17 January 2008 Paul Soler

  2. Contents • MIND summary and tasks • Synergy with TASD: develop common software (TASD performance covered by Walter for low E Neutrino Factory) • Near Detector summary and tasks • Note: no discussion of silver detectors Neutrino Factory International Design Study Meeting RAL 17 January 2008

  3. MIND 100 m 14 m n beam M~100 KTon 14 m 1cm transverse resolution B=1 T iron (4 cm) scintillators/RPCs (1cm) Easy to detect muons in iron by range Easy to discriminate against hadron showers Easy to magnetise iron Based in known technology: ~MINOS Can be very massive cannot detect electrons or taus Cost is not prohibitive: 300-400 M$ the energy threshold is high Neutrino Factory International Design Study Meeting RAL 17 January 2008

  4. Simulation and resolution • Detector effects not simulated • Perfect pattern recognition • Reconstruction based on parameterisation • Dipole field instead of toroidal field Essential to measure the oscillation pattern Crucial to solve degeneracies Ehad • Fully contained muons by range • Scaping muons by curvature • Hadron shower: Em Including QE Neutrino Factory International Design Study Meeting RAL 17 January 2008

  5. Kinematic cuts Neutrino Factory International Design Study Meeting RAL 17 January 2008

  6. Lμ >75 cm Lμ >150 cm Charge identification • Simple exercise. Assumptions: • No border effects • Non-gaussian scatters can be identified via local χ2 criterion with a Kalman Filter • Assume gaussian MS • Gluckstern formula + MS term BFe =1.25 T 1.7 T 2T • Event simulation • Realistic flux • Non-gaussian MS • Border effects • LSQ fit Neutrino Factory International Design Study Meeting RAL 17 January 2008

  7. Wrong charge assignments Neutrino Factory International Design Study Meeting RAL 17 January 2008

  8. Backgrounds Neutrino Factory International Design Study Meeting RAL 17 January 2008

  9. Lμ> 75 cm Lμ>150 cm Lμ>200 cm Signal efficiency • Efficiency plateau between 5 and 8 GeV depending on Lμcut nmCC signal • baseline: Lμ > 150 cm • Ensures charge mis-ID below 10-3 Old analysis II: Pμ>5 GeV, Qt> 0.7 GeV Old analysis I: Pμ>7.5 GeV, Qt> 1 GeV Neutrino Factory International Design Study Meeting RAL 17 January 2008

  10. Aims of full simulation/reconstruction • Demonstrate that for En < 10 GeV • Backgrounds are below 10-3 • The efficiency can be increased with respect to fast analysis • Compute: • Signal and backgrounds efficiency as a function of energy • Energy resolution as a function of energy • Identify crucial parameters to be optimised to maximise the sensitivity to the osc. parameters • Optimise segmentation and B field based on the above parameters and taking into account feasibility and cost Neutrino Factory International Design Study Meeting RAL 17 January 2008

  11. Hadron shower Fast analysis • Hadrons are stopped when they decay or undergo a nuclear interaction • We then record their energy and momenta: p1, p2, ..., E1,E2, ... • Their length is also recorded: L1, L2, ... The hadron shower energy and angle are smeared according to MINOS proposal + MINOS CalDet + Monolith testbeam Neutrino Factory International Design Study Meeting RAL 17 January 2008

  12. Muon • Muon is followed until it stops, decays or escapes the detector • The position of all hits is recorded • And also its 3-momentum Fast analysis m+ • Muon hits are smeared with 1cm transverse resolution • A track fit gives its charge • For the kinematical analysis the muon momentum is smeared according to Gluckstern formula + MS term Neutrino Factory International Design Study Meeting RAL 17 January 2008

  13. In real life • The muon is not isolated: pattern recognition • 2 independent views XZ and YZ that should be matched • The event sense can be computed from timing (?) Neutrino Factory International Design Study Meeting RAL 17 January 2008

  14. Recon vertex Cellular automaton Kalman filter Muon reconstruction m+ • Reconstruct the vertex from event topology • Cellular automaton or Hough transform for planes with small activity • Match X and Y views in planes with small activity • Find approximate muon parameters based on these planes and vertex • Incremental Kalman Filter from the end of the track towards vertex • Multiple scattering, energy loss and B field map Neutrino Factory International Design Study Meeting RAL 17 January 2008

  15. Steps Neutrino Factory International Design Study Meeting RAL 17 January 2008

  16. Event generation • Only DIS interactions as coming from LEPTO has been generated so far • Including QE and RES should have a big impact at low neutrino energies: • No hadron shower: • Easy pattern recognition • Better neutrino energy resolution • Help in improving the threshold energy and reduce backgrounds • Generators: Nuance, Neut, Neugen, Genie Neutrino Factory International Design Study Meeting RAL 17 January 2008

  17. 100 m 15 m 15 m Synergies with TASD • Scintillator bars, PD and electronics are the same. This is the most difficult part • B field production is different and more difficult A common framework for simulation and reconstruction (M. Ellis) Neutrino Factory International Design Study Meeting RAL 17 January 2008

  18. Detector optimisation: Longitudinal segmentation Neutrino Factory International Design Study Meeting RAL 17 January 2008

  19. Detector optimisation: Transverse segmentation • Assuming perfect pattern recognition 1 cm transverse resolution is enough for charge and Qt measurements • Pattern recognition: • better segmentation should improve it • which resolution saturates the patter recognition performance ? Lines: 1, 1.5 and 2 GeV/c muon momentum BFe=2 Tesla Fe thickness = 2.5 cm BFe=1.25 Tesla Fe thickness = 4 cm BFe=1.25 Tesla Fe thickness = 2.5 cm Neutrino Factory International Design Study Meeting RAL 17 January 2008

  20. Detector optimisation:magnetic field • Even if we are able to isolate a 1 GeV/c muon, the ratio curvature/MS is not sufficient. ~5% charge mis-ID • The magnetic field strength is the crucial parameter • Going from 1.25 to 1.7 Tesla average is feasible (J. Nelson, Golden07) • > 1 o.o.m improvement at 1 GeV/c. 10-3 level MINOS MIND 1 GeV/c 2 GeV/c 1.5 GeV/c Neutrino Factory International Design Study Meeting RAL 17 January 2008

  21. Conclusions MIND • Fast simulation/reconstruction was very useful until now • But it’s time to move forward with a full simulation/reconstruction • What are the main backgrounds at low energies ? • What is the background level ? • Where is the efficiency plateau ? • What are the parameters to be optimised ? • Prototyping program should go in parallel Neutrino Factory International Design Study Meeting RAL 17 January 2008

  22. Sim/Rec/Analysis task list • Event simulation (NUANCE)--> bHEP1 • converter between NUANCE and bHEP format • Event transport (GEANT4) --> bHEP2 • Geometry and bHEP interface • Digitisation --> bHEP3 • hits: • 2D points, pulse height, time • link to true particle • Dummy digitisation with MIND fast simulation • Reconstruction --> root file • Build the framework: • Define bHEP format • Read dst (bHEP) • Event likelihood • Cellular automaton (import from T2K) • Kalman filter (RecPack) Identified manpower for these tasks In Valencia/Brunel/Glasgow + EuroNu manpower Tasks to be done in parallel Neutrino Factory International Design Study Meeting RAL 17 January 2008

  23. Beam Diagnostics and Near Detector aims • Beam diagnostics (needed for flux measurement) • Number of muon decays • Measurement of divergence • Measurement of Muon polarization • Near detector measurements needed for neutrino oscillation systematics: • Flux control for the long baseline search. • Measurement of charm background • Cross-section measurements: DIS, QES, RES scattering • Other near detector neutrino physics (electroweak and QCD): • sin2W - sin2W ~ 0.0001 • Unpolarised Parton Distribution Functions, nuclear effects • Polarised Parton Distribution Functions – polarised target • Lambda (L) polarisation • S from xF3 - S~0.003 _ • Charm production: |Vcd| and |Vcs|, CP violation from D0/ D0 mixing • Beyond SM searches • … Neutrino Factory International Design Study Meeting RAL 17 January 2008

  24. shielding the charm and DIS detector Cherenkov Polarimeter the leptonic detector BCT storage ring Beam Diagnostics • Beam Current Transformer (BCT) to be included at entrance of straight section: large diameter, with accuracy ~10-3. • Beam Cherenkov for divergence measurement? Could affect quality of beam. Neutrino Factory International Design Study Meeting RAL 17 January 2008

  25. Beam Diagnostics • Muon polarization: Build prototype of polarimeter Fourier transform of muon energy spectrum amplitude=> polarization frequency => energy decay => energy spread. Neutrino Factory International Design Study Meeting RAL 17 January 2008

  26. Flux Measurement at Near Detector • Best possibility: Inverse Muon Decay: scattering off electrons in the near detector. Known cross-sections Neutrino Factory International Design Study Meeting RAL 17 January 2008

  27. Near Detector used to extract Pnenm • Use matrix method with Near Detector data (even if spectrum not identical in near and far detector!) to extract oscillation probability: • Where: M1=matrix relating event rate and flux of ne at ND M2=matrix relating event rate and flux of nm at FD M=matrix relating measured ND ne rate and FD nm rate MnOsc=matrix relating expected ne flux from ND to FD • Method works well but need to extract syst errors of method: Probability of oscillation determined by matrix method under “simplistic” conditions. Need to give more realism to detector and matter effects. Neutrino Factory International Design Study Meeting RAL 17 January 2008

  28. Charm measurement • Motivation: measure charm cross-section to validate size of charm background in wrong-sign muon signature • Charm cross-section and branching fractions poorly known • Semiconductor vertex detector only viable option in high intensity environment (emulsion too slow!) Neutrino Factory International Design Study Meeting RAL 17 January 2008

  29. Cross section measurements • Measure of cross sections in DIS, QE and RES. • Coherent p • Different nuclear targets: H2, D2 • Nuclear effects, nuclear shadowing, reinteractions What is expected cross- section errors from MiniBoone, SciBoone, T2K, Minerva, before NUFACT? At NUFACT, with modest size targets can obtain very large statistics, but is <1% error achievable? Neutrino Factory International Design Study Meeting RAL 17 January 2008

  30. Other physics: Parton Distribution Functions • Unpolarised and Polarised Parton Distribution Functions • S from xF3 - S~0.003 • Sum rules: e.g. Gross-Llewelyn Smith • L polarization: spin transfer from quarks to L • NOMAD best data • Neutrino factory 100 times more data Neutrino Factory International Design Study Meeting RAL 17 January 2008

  31. EM calorimeter Hadronic Calorimeter Muon chambers Near Detector Design • Overall design of near detector(s): • Near Detector could be a number of specialised detectors to perform different functions (ie. lepton and flux measurement, charm measurement, PDFs, etc.) or larger General Purpose Detector Neutrino Factory International Design Study Meeting RAL 17 January 2008

  32. Near Detector Conclusions • Near Detector considerations: optimisation design • Vertex detector: Choice of Pixels; eg. Hybrid pixels, Monolithic Active Pixels (MAPS), DEPFET; or silicon strips • Tracker: scintillating fibres, gaseous trackers (TPC, Drift chambers, …) • Other sub-detectors: PID, muon ID, calorimeter, … • Tasks: • Simulation of near detector and optimisation of layout: could benefit from common software framework for Far Detector • Flux determination with inverse muon decays, etc. • Analysis of charm using near detector • Determination of systematic error from near/far extrapolation • Expectation of cross-section measurements • Test beam activities to validate technology (eg. vertex detectors) • Construction of beam diagnostic prototypes • Other physics studies: PDFs, etc. (engage with theory community for interesting measurements) Neutrino Factory International Design Study Meeting RAL 17 January 2008

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