Partially Contained Atmospheric Neutrino Analysis Andy Blake Cambridge University March 2004

Introduction Far Det data: R – (1.2 kT-yrs) MC atmos nu: R 124 (250 kT-yrs) R 1.5 software: PhotonTransport / DetSim FC/PC Filter AltDemux + AtNuReco MCdata

PC digits Define fiducial volume: > 50cm from detector edge in UV > 4 planes from detector edge in Z Combine digits in adjacent views. Select events with: > 10 PE inside fiducial volume > 5 PE outside fiducial volume beside ONE detector edge.

PC tracks Select events with: ONE track + ONE vertex inside fiducial volume. bottom vertex contained top vertex contained upward-going candidate downward-going candidate “direction” problem“containment” problem

Track Quality Cuts (1) Tracks reconstructed by AtNuReco in 1 st pass > 7 planes > 30% of total pulseheight Simple timing cut ( bottom vertex contained → Χ 2 up < Χ 2 down top vertex contained → Χ 2 down < Χ 2 up ) Match PC track + PC digit containment Track Quality Cuts:

Track Quality Cuts (2) DATASIGNAL PC DIGITS130, PC TRACK (DOWN) 7, TRACK QUALITY (DOWN) 1, PC TRACK (UP) TRACK QUALITY (UP)

Down-Going PC Events

Down-Going Muons (1) Increase PH cut to 50% PH track / PH total > 0.5 or R steel / PH total > 0.5 (1) Pulse Height PH track / PH total > 0.5

Down-Going Muons (2) TRACE Z extrapolate track to detector edge + calculate Z distance Trace Z > 7 planes (2) Trace

Down-Going Muons (3) (3) Track Vertex R max < 36 stripsQ max < 250 PE Furthest off-track hit in ± 3 plane window around vertex Highest pulse-height plane in ± 3 plane window around vertex

Down-Going Muons (4) DATA (33 events) DETECTOR EFFECTS (15 events) CONTAINED EVENTS (18 events) CRATE BOUNDARIES (11 events) HV TRIPS (4 events) STEEP MUONS (10 events) “IRREDUCIBLE” (8 events) apply veto shield

Detector Effects : Crate Boundaries (1)

Detector Effects : Crate Boundaries (2) run 20339, snarl 60473

Detector Effects : HV Trips (1)

Detector Effects : HV Trips (2)

“Steep Muons”

Veto Shield Use CandShieldPlanks –Q > 1 PE –ΔT < 400 ns –Y shield > Y track –Z shield ~ Z track Estimate tagging efficiency by reducing containment cuts: –Tagging efficiency ~ 97% Estimate accidental tagging by using pre-trigger shield hits: –Accidental Tagging ~ 3%

Down-Going Muons (5) DATASIGNAL PC TRACK7, TRACK QUALITY1, PULSE HEIGHT1, TRACE Z534.3 VERTEX334.1 DATA QUALITY184.1 VETO SHIELD54.0 BACKGROUND: expected background before shield ≈ 18 – 4 ≈ 14 ≈ 3.5 x signal expected background after shield ≈ 0.03 x 14 ≈ 0.4 ≈ 0.1 x signal

Down-Going Candidates (1)

Down-Going Candidates (2)

Down-Going Candidates (3)

Down-Going Candidates (4)

Down-Going Candidates (5)

Up-Going PC Events

Up-Going Muons (1) S CT U view V view 1/β = -11/β = +1 Fit S-CT with time slope ± 1 Calculate RMS for each fit Consider RMS up - RMS down Timing Cuts RMS down – RMS up > 0.3

Up-Going Muons (2) RMS up < 1.5 mRMS down > 1.0 m

Up-Going Muons (3) RMS up / RANGE < 0.5 RMS from fitting wrong time slope fit track 0 S

Up-Going Muons (4) 1/β > 0.51/β < 2.5

Up-Going Muons (5) DATASIGNAL PC TRACK TRACK QUALITY RMS down - RMS up RMS up, RMS down RMS up / RANGE / β43.6 BACKGROUND: … use MC stopping muons with tuned timing resolution.

Up-Going Candidates (1)

Up-Going Candidates (2)

Up-Going Candidates (3)

Up-Going Candidates (4)

Signal Efficiencies (1) Containment cutsDirection cuts

Signal Efficiencies (2) Efficiency vs Neutrino EnergyEfficiency vs Muon Zenith Angle

Conclusion Able to extract PC candidates from data. Analysed <50% of data – more events to come! Further development of analysis. –Tag events contained due to detector effects. –Continue battling with steep muons. Neutrino energy reconstruction. –Lots of ideas being developed at Cambridge!