Update on Contained ne Atmospheric Analysis

1
Update on Contained ne Atmospheric Analysis

• Ben Speakman
• AtNu WG Parallel Session
• Tufts Week in the Woods
• 2006/06/08

2
Analysis Motivation and Goals

• Isolate ne CC events in the atmospheric neutrino
  sample
• Measure the flux to normalize the flux model for
  the nm CC analysis (currently uses Soudan2 ne
  flux normalization -- 10 error)
• Evaluate oscillation with (nm/ne)Data/MC double
  ratio

3
Data Sets Used

• Cambridge reconstruction of the set used for the
  paper 418 Live Days 8/03 2/05
• Monte Carlo
• Atmospherics 1261.3 kTy exposure
• 18.3M CR m Musser Flux

4
LI Rejection and Preselection

• Base 418 Live Day Set
• Standard DQ Cuts
• TPMT -30ms cut
• Coded LISieve for AtmosEvent(Jeff / Phil)
• Fraction of SE Strips lt 0.8
• Max LED PE Fraction and Max Pulser Box Occupancy

5
PBOccup vs MaxLEDPEFrac

• Runs 26776 and 26779 find a set of events that
  arent rejected by the previous cuts
• This combines the techniques of LISieve and Fancy
  LI Pattern Finder in FilterLI package

Cut (MaxPBOccupgt0.7) (MaxLEDPEFracgt0.5)
6
FC Shower Selection

• Preselection (1 Shower and No Tracks)
• Shower Octagonally Contained to 3.5m and gt 5
  Planes from edge
• Shower must be gt 4 Planes and have gt 8 Strips
• UpTraceZ for shower direction pointed upwards gt
  0.8
• Largest MOI Solution Eigenvalue lt 0.063
• ltStrips/Plane2gt1/2 lt 2.0
• 7.9 100.9 lt Log10(ltPE/Plane2gt1/2) lt 102.2
  158
• ltDShwCoregt lt 10-0.8 0.158
• MOI Primary Axis Cosqy lt 0.9
• Veto Shield Selection

7
TraceZ Cut

• Follow shower axis to 2 detector edges
• Take edge with higher Y and find Dz

UpTraceZ gt 0.8
8
MOI Eigenvalue Cut

• Fill MOI Tensor and Solve
• Largest Eval describes length / width parameter

MaxEVal lt 10-1.2 0.063
9
RMS (Strips / Plane)

• Width in the distribution on Strips by Plane

VarStpPln lt 2.0
10
RMS (PE / Plane)

• Width in the distribution on PE by Plane
• Low cut to start taking care of nm background

7.9 lt VarEPln lt 158 0.9 lt Log10(VarEPln) lt 2.2
11
Mean D Hit Shower Core

• PE Weighted mean of perpendicular distance from
  Shower Axis

ltDShwCoregt lt 100.8 6.3
12
Shield Cut

• Whole section in-time (100ns) charge cut
• Use section directly above event, adjacent
  section if near border, and section pointed back
  to by HiY end
• Veto if associated sections contain any in-time
  energy

13
Shower Shield Efficiency

• Shield efficiency for showers had a deficit
  around the SM2 section break
• Reapply cut to include both sections for
  (359ltShw.VtxPlanelt368)
• Overall efficiency from (97.3 0.1) to (97.5
  0.1), uniformly in time
• Doesnt change final selection

14
FC Shower selection results
15
Resulting Shower Events

• 108 Event pass final cuts
• 48.9 0.5 ne CC
• 13.4 0.4 nm CC
• 9.79 0.2 oscillated(SK)
• 11.5 0.1 n NC
• 6.4 0.4 CR m
• 80.2 5.3 Total Predicted
• 76.6 5.3 oscillated(SK)

16
Shower Energy Distribution
17
Shower Energy Distribution
18
Shower Energy Distribution
19
Separated Low / High E Events
Red Eshw lt 1Gev Black Eshw gt 1GeV
20
nm Analysis
21
FC Track Selection

• Preselection 1 Track
• TrkPlanes gt 8 TrkLikePlanes gt5
• Octagonally Contained (3.5m) Track vertex and end
• gt50 of PH Associate with track and lt500PE in
  any one Plane
• Vertex TraceZ gt 0.5
• VtxRdigits gt 0.5
• ltDtgt(U,V) lt 0.25 ltDt2gt1/2(U,V) lt 0.5
• QmaxVtx lt 300PE for TrkPlanes lt 20
• Qmaxvtx lt 100PE for TrkPlane lt 20 (Cosqzgt0.5
  Cosqygt0.7)

22
FC Track selection results
23
Resulting Track Events

• 69 Event pass final cuts
• 92.40.7 nm CC
• 67.40.6 oscillated(SK)
• 2.40.1 ne CC
• 2.10.1 n NC
• 4.40.3 CR m
• 101.35.4 Total Predicted
• 76.35.3 oscillated(SK)

24
nm / ne flux determination and double ratio
Flux Normalization 1.39 0.16 (UnOsc)
1.45 0.17(Osc)
Unoscillated Double Ratio (Nnm/Nne)Data/MC
0.467 0.088(stat)
Oscillated Double Ratio (Nnm/Nne)Data/MC 0.612
0.11(stat)
25
Unresolved Issues

• Understand these low energy showers
• Shield Selection and efficiency
• Systematics

26
Backup Slides
27
Acceptance vs True Energy
28
Track Shield Efficiency

• Similar, but less pronounced SM2 section gap.
• Reapply cut to include both sections for
  (359gtShw.VtxPlanegt368)
• Overall efficiency from 97.4 0.2 to 0.975
  0.002, uniformly in time
• Doesnt change final selection