miniboone - fermilab · 2015. 12. 2. · laser flask: • prompt monochromatic light pulsed via 397...

MiniBooNE

Hirohisa A. TanakaPrinceton University

Weak Interactions and Neutrinos Workshop 2003 (Lake Geneva, WI)

H. A. Tanaka – WIN 2003 1

Overview:

BooNE: Booster Neutrino Experiment

• The Beam

• The Detector and Calibration Devices

• Beam Data

• Conclusions

See Andrew Bazarko’s talk for oscillation discussion


BooNE is for Booster:

The Fermilab Booster:

• 8 GeV protron synchrotron

Provides protons for:

• MiniBooNE

• Main InjectorAntiprotons, Tevatron

120 GeV Fixed Target, NuMI

MiniBooNE beamline

• 1.6 µsec p batch on Be

• Electromagnetic Horn (+)Focus 2ndary particles

• 50 m decay region π+ → µ+νµ

Design Performance

• 5× 1012 p/batch at 5 Hz

• 5× 1020 POT/year


BooNE is for Neutrino:

10-5

10-4

10-3

10-2

10-1

0 0.5 1 1.5 2 2.5 3E n (GeV)

Frac

tion

of n

m F

lux

/ 0.1

GeV

nm Fluxne Flux

PRELIMINARY Predicted Neutrino Flux:

• Sanford-Wang parameterization:Global fit to p− Be π+ data

• Kaons from MARS

• Dominant Processes at ∼ 1 GeV:

• CC Quasi-elastic

• NC Elastic

• Resonance

Comparable energies to Off-Axis proposals


BooNE is for Experiment:

MiniBooNE:

• 540 m from target

• 6.1 m radius sphereMineral oil target

• Optical barrier at 575 cm

• Inner “Tank” region

• Outer Veto region

• 1280 8” PMTs in Tank (10%)

• 240 8” PMTs in Veto

Detect neutrino interactions via C and Scintillation light


Calibration Devices:

Muon Tracker + Cubes:

• Muon Hodoscope above detector

Four layers of scintillator bars

Independent track reconstruction

• Scintillator Cube

Seven cubes throughout detector

Independent vertex reconstruction

Stopping muons with precisely known pathlength

Laser Flask:

• Prompt monochromatic light

Pulsed via 397 and 438 nm laser

• Varying intensity

sub-1 p.e. → multi p.e.

• Varying location

Four flasks + bare fiber in detector.

Study PMT hit reconstruction

Study oil optical properties.


The CollaborationUniversity of Alabama Y.Liu, I.Stancu

Bucknell University S.Koutsoliotas

University of Cincinnati E.Hawker, R.A.Johnson, J.L.Raaf

University of Colorado T.Hart, R.H. Nelson, E.D.Zimmerman

Columbia University A. Aguilar-Arevalo, L.Bugel, J.M.Conrad, J.Formaggio,

J.Link, J.Monroe, D. Schmitz, M.H.Shaevitz,

M.Sorel, G.P. “Sam” Zeller

Embry Riddle Aeronautical University D.Smith

Fermi National Accelerator Laboratory L.Bartoszek, C.Bhat, S.J.Brice, B.C.Brown, D.A.Finley,

B.T.Fleming, R.Ford, F.G.Garcia, P.Kasper, T.Kobilarcik,

I.Kourbanis, A.Malensek, W.Marsh, P.Martin, F.Mills,

C.Moore, P.Nienaber, E.Prebys, A.D.Russell,

P.Spentzouris, R.Stefanski, T.Williams

Indiana University D.C. Cox, J.A. Green, H.Meyer, R.Tayloe

Los Alamos National Laboratory G.T.Garvey, C. Green, W.C.Louis, G.McGregor,

S. McKenney, G.B.Mills, V.Sandberg, B.Sapp, R.Schirato,

R.Van de Water, N. Walbridge, D.H.White

Louisiana State University R.Imlay, W.Metcalf, M.Sung, M.Wascko

University of Michigan J.Cao, Y.Liu, B.P.Roe

Princeton University A.O.Bazarko, P.D.Meyers, R.B.Patterson,

F.C.Shoemaker, H.A.Tanaka


Neutrino Data:

• Inclusive distributions

• Charged Current quasi-elastic scattering

• Neutral Current elastic scattering

• Neutral Current π0 production

∼ 1× 1020 protons-on-target analyzed

Comparisons to Monte Carlo are relatively normalized.

See Andrew Bazarko’s talk for discussion on Oscillation Analysis


Neutrino Events!

sec)mAverage Tank Time (4 6 8 10 12 14 16 18

sec

mE

vent

s/0.

2

0

5000

10000

15000

20000

25000

All Events

Event time is calculated from “subevent”:First cluster of > 10 hits contiguous in time.

Beam Events:

• Arrive in 1.6 µsec window[4.6, 6.2] µsec

• Event time:From average of tank hits

• Excess is clearly seen

Backgrounds:

• Cosmic Muons

• Decay electrons

Backgrounds can be eliminated with multiplicity cuts (Tank/Veto PMT Hits).


Neutrino Events!

Veto cut eliminates cosmic µ:

• Single MIP ∼ 18 hitsMost are throughgoing.

• Eliminate with NV ETO < 6

Remaining Background:

• Decay electrons (< 200 Hits)Muon enters before window.

• Env./Noise (< 20 Hits) sec)mAverage Tank Time (4 6 8 10 12 14 16 18

sec

mE

vent

s/0.

2

0

1000

2000

3000

4000

5000

6000<6VETON

Remaining background eliminated with Tank Multiplicity cut.


Neutrino Events!

sec)mAverage Tank Time (4 6 8 10 12 14 16 18

sec

mE

vent

s/0.

2

0

500

1000

1500

2000

2500

3000>200TANK<6, NVETON

Remaining background eliminated with NTANK > 200. S/B > 1000

∼ 150K “clean” candidates in ∼ 1.5× 1020 protons-on-targetApproximately 50%/50% CC Quasi-elastic/Single Pion


νµ Quasi-Elastic Events:

Size of Ball = Charge

Red = early, Blue = late

nm m-

n p

W

CX

νµ + n → µ− + p

• Abundant (40%)

• Simple topology:one muon-like ringproton rarely above C threshold

• Obtain Eµ, θµ from fit


Selecting Quasi-Elastic Events:

Selection

• Single µ-like ring, decay electron

• Ring profile/sharpness

• Time of hits

• Minimize energy bias

→ Fisher discriminant

• MC indicates ∼ 88% puritySome background is irreducible

• Relatively well-known cross section

→ cross-check of flux prediction∼ 28K CC QE candidates

0

0.1

0.2

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1cos qm

Frac

tion

of E

vent

s / (1

/15)

Data

Monte Carlo

0

0.1

0.2

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1cos qm

Frac

tion

of E

vent

s / (1

/15)

Data

Monte Carlo


Neutrino Energy:0

(GeV)GenmnE

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

Gen mn

/Emn

ED

0

0.1

0.2

0.3

0.4

0.5

0

2

GennEb + 2 = a

2 Gen

nEn ED

a = 3.788008e-02b = 8.364264e-02

PRELIMINARYMonte Carlo-simulatednm CC quasi-elastic events

Kinematic Reconstruction:

Assume:νµ + n → µ− + p

→ obtain Eν via Eµ, θµ

Account for:

• Binding energy

• Muon mass

• C threshold

∼ 10% resolution for Eν > 500 MeV


Q2 and Eν :

0

0.1

0.2

0.3

0 0.5 1 1.5 2 2.5 3

Q2 (GeV2)

Fra

ctio

n of

Eve

nts

/ 0.1

GeV

2

Data

Monte Carlo

Q2 = −(pν − pµ)2

• Form factors (f1,2, g1) depend on Q2

• Nuclear effects at low Q2

Eν (Incident Neutrino Energy):

• Measures incident flux

0

0.1

0.2

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1cos qm

Frac

tion

of E

vent

s / (1

/15)

Data

Monte Carlo


Neutral Current Elastic Scattering:

0 200 400 600 800 1000 120002000400060008000

10000120001400016000180002000022000

Eve

nts

Tank Hits

PRELIMINARY

Neutral Current Elastic

All Events

νµ + (p/n) → νµ + (p/n)• Typically sub-C:

Dominated by scintillation

• low NTANK, large late light fraction

• Large cross section (∼ 15%)

• Sensitive to strange spin component

Background subtraction:• Beam excess clearly visible

Non-beam background

• Decay electrons

• Environmental

• Subtract with random triggers

s)mAvg. PMT Time (0 2 4 6 8 10 12 14 16 18 20

0

5000

10000

15000

20000

25000

30000

35000

40000

All Beam DataEve

nts

0 2 4 6 8 10 12 14 16 18 200

5000

10000

15000

20000

25000

30000

35000

40000

Normalized Strobe DataEve

nts

0 2 4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Beam after

Strobe Subtraction

Eve

nts

PRELIMINARY PRELIMINARY PRELIMINARY

s)mAvg. PMT Time ( s)mAvg. PMT Time (


Neutral Current Hit Spectrum:Low multiplicity events:

• Strobe background subtraction

• Unknown component NTANK < 30

• 50 hit threshold for vertex fitNormalize MC to NTANK > 50 yield

Tank Hits0 20 40 60 80 100 120 140 160 1800

2000

4000

6000

8000

10000

Eve

nts

Beam DataMonte Carlo

THits (Hits)0 20 40 60 80 100 120 140 160 1800

200

400

600

800

1000

Eve

nts/

10 H

its

Beam DataMonte CarloMC, NC Elastic

PRELIMINARY Late light Selection:

• Fit event vertex for NTANK > 50 events

• Calculate fraction of late hits

• Select events with significant late light

Agreement for NTANK > 50 with/without late light cut.


Neutral Current π0 Production:

Physics Interest:

• Background for νe

• Limits on Sterile ν

Primary Mechanisms:

• Resonance:

ν + (p/n) → ν + ∆∆ → (p/n) + π

• Coherent:

ν + C → ν + C + π0Size of Ball = Charge

Red = early, Blue = late


Reconstructing Two Ring Events:

Blue: Cherenkov Light

Red: Scintillation

• Fourteen parameter fit:

• Vertex of decay (4)

• Direction of photons (4)

• Mean emission points (2)

• C/Sci Intensity(4)

• Kinematics from C Intensity

• mc2 =√

2E1E2(1− cos θ12)• ~p = E1u1 + E2u2

E1, E2 derived from C rings.

• No (e/µ) Ring Identification


Inclusive Mass Distribution:

)2 Mass (GeV/c0.1 0.2 0.3 0.4 0.5

)2Ev

ents

/ ( 0

.02

GeV

/c

0

200

400

600

800

1000

0.1 0.2 0.3 0.4 0.50

200

400

600

800

1000

Mass = 0.1356 ± 0.0009 2GeV/c

Width = 0.0209 ± 0.0009 2GeV/c

= 0pNum. 2425 ± 107 Events

PRELIMINARY

Signal + BackgroundBackground

Bin data in kinematic quantities:

• Momentum (pπ0)

• Angle relative to beam (cos θπ0)

• CM Decay angle (cos θCM)

Event Selection:

• No decay electrons

• NTANK > 200, NV ETO < 6

• E1, E2 > 40 MeV

Signal shape from Res.+Coh. π0s

Background shape from Monte Carlo(Contains π0s from FSI, etc.)

EML Fit to extract signal yield

Extract binned yields

→ Get distribution


π0 Angular Distributions:

CMqcos 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Fra

ctio

n of

Eve

nts/

0.1

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

Data w/ statistical errors

yield extraction systematic errors

PRELIMINARY

MC w/ statistical +

π0 Lab Production AngleSensitive to production mechanism

• Coherent is highly forward peaked

• Resonance is less forward-peaked

MC assumes Rein-Sehgal cross-sections

π0 CM Decay Angle

• Should be flat (pseudoscalar)

• Distorted by Eγ cut, inefficiency

• Probes inefficiencies from:asymmetry, ring merging

0pqcos -1 -0.5 0 0.5 1

Fra

ctio

n of

Eve

nts/

0.2

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35


MC w/ statistical +yield extraction systematic errors

PRELIMINARY


π0 Momentum Distribution :

Momentum (GeV/c)0p0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Fra

ctio

n of

Eve

nts/

0.1

GeV

/c

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35


MC w/ statistical +yield extraction systematic errors

PRELIMINARY

Higher Momentum means:

• Energy asymmetry

• Smaller opening angle

Harder to Reconstruct


Physics Outlook:

• CC Quasi-Elastic:Compare with flux predictions →νµ disappearance analysis.Probe low Q2 region

• Neutral Current Elastic:Measure σNC/σCC vs. Q2

Probe ∆s.

• NC π0 Production:Cross-section measurementBackground extrapolationAnalyze coherent contribution

10-1

1

10

10 2

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

sin2 2qmm

Dm

2 (eV

2 )

CDHS 90% CL exclusion limit

CCFR 90% CL exclusion limit

MiniBooNE 90% CL sensitivityPRELIMINARY

0pqGenerated cos -1 -0.5 0 0.5 1

Fra

c. E

v/0.

04

0

0.05

0.1

0.15

0.2

0.25

0.3

Coherent

Resonant


Conclusions:

• MiniBooNE has been taking beam for ∼ 1 year.

• 1.5× 1020 protons-on-target

• 150K contained neutrino candidates

• Detector is working as expected.

• Reconstruction algorithms working well

• First sample of neutrino physics

More to come!


miniboone - fermilab · 2015. 12. 2. · laser flask: • prompt monochromatic light pulsed via 397...

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