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!