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Partially Contained Atmospheric Neutrino Analysis
Andy BlakeCambridge University
March 2004
Introduction• Far Det data: R 18140 – 22330 (1.2 kT-yrs)• MC atmos nu: R 124 (250 kT-yrs)• R 1.5 software:
PhotonTransport / DetSim
FC/PC Filter
AltDemux + AtNuReco
MC data
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 vertexcontained
top vertex contained
upward-going candidate
downward-going candidate
“direction” problem “containment” problem
Track Quality Cuts (1)
• Tracks reconstructed by AtNuReco in 1st pass
• > 7 planes
• > 30% of total pulseheight
• Simple timing cut ( bottom vertex contained → Χ2
up< Χ2down
top vertex contained → Χ2down< Χ2
up )
• Match PC track + PC digit containment
Track Quality Cuts:
Track Quality Cuts (2)
DATA SIGNAL
PC DIGITS 130,000 16.2
PC TRACK (DOWN)
7,500 6.5
TRACK QUALITY(DOWN)
1,500 5.1
PC TRACK(UP)
850 6.5
TRACK QUALITY
(UP)250 5.0
Down-Going PC Events
Down-Going Muons (1)
• Increase PH cut to 50%
PHtrack / PHtotal > 0.5
or
400.0 Rsteel / PHtotal > 0.5
(1) Pulse Height
PHtrack / PHtotal > 0.5
Down-Going Muons (2)
TRACE Zextrapolate trackto detector edge + calculate Z distance
Trace Z > 7 planes
(2) Trace
Down-Going Muons (3)(3) Track Vertex
Rmax < 36 strips Qmax < 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
– Yshield > Ytrack
– Zshield ~ Ztrack
• 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)
DATA SIGNAL
PC TRACK 7,500 6.5
TRACK QUALITY 1,500 5.1
PULSE HEIGHT 1,400 4.7
TRACE Z 53 4.3
VERTEX 33 4.1
DATA QUALITY 18 4.1
VETO SHIELD 5 4.0
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 viewV view
1/β = -11/β = +1
• Fit S-CT with time slope ± 1• Calculate RMS for each fit• Consider RMSup - RMSdown
Timing Cuts
RMSdown – RMSup > 0.3
Up-Going Muons (2)
RMSup < 1.5 m RMSdown > 1.0 m
Up-Going Muons (3)
RMSup / RANGE < 0.5
• RMS from fitting wrong time slope
fit
track
3
1
3
)2( 2
2/
0
2/
0
2
2
RANGE
RMSS
dx
dxxRMS
S
S
0
S
Up-Going Muons (4)
1/β > 0.5 1/β < 2.5
Up-Going Muons (5)
DATA SIGNAL
PC TRACK 850 6.5
TRACK QUALITY 250 5.0
RMSdown - RMSup 44 4.5
RMSup, RMSdown 16 4.4
RMSup / RANGE 8 3.8
1 / β 4 3.6
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 cuts Direction cuts
Signal Efficiencies (2)
Efficiency vs Neutrino Energy Efficiency 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!
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