SciBooNE experiment（実験の意義・目的と現状など）

Y.Hayato

1. Neutrino – nucleus scattering experiment

反応の詳細を実験データから知ることが必要

１）散乱断面積a)反応の全散乱断面積b)微分散乱断面積

２）生成粒子とそれらの運動量分布

ニュートリノ振動実験

シミュレーションプログラムを用いて期待される分布を求め、データと比較することで振動パラメータを決定する。

できるだけ「正しい」シミュレーションプログラムが必要反応標的として酸素や炭素などを用いる場合、

原子核であることの影響が大きい。正確なモデル化を行うことも非常に難しい。

ニュートリノと電子や核子散乱により生成した　　　　　　　荷電粒子 (など )を観測することで行う。

2. Neutrino interactions above 100MeVCharged current quasi-elastic scattering

Neutral current elastic scattering

Single ,,K resonance productions

Coherent pion productions

Deep inelastic scattering

+ n →- + p

+ N →l + N’ + (,K)

+ N → + N

+ X →l + X’ +

+ N →l + N’ + m(,K)(l : lepton, N,N’ : nucleon, m : integer)

/E

(10

-38 c

m2 /

GeV

)

Total (NC+CC)

CC Total

CC quasi-elastic

DISCC single

NC single 0

E (GeV)

cross-sections

cross-sections

CC Total

DIS (CC)

3. Existing – nucleus scattering dataMainly from the bubble chamber experiments

Also, the flux estimation has large uncertainties.Still, there seems to exist quite large uncertainties

even in the current running experiments.

(ANL)

Bubble chamber is a very powerful detector.High efficiency in detecting

even for low momentum charged particles.

Determination of the “absolute” cross-section is difficult.

• Limited by statistics.( Scanned by eye, basically. )

　　　 A few tens to hundreds events. A few thousands events at most.• / charged separation

was rather difficult.• 0 detection efficiency was not high.

3. Existing – nucleus scattering dataRecent experiments 1) K2K

Water Cherenkov detectorSciFi detectorSciBar detector

2) MiniBooNEMineral oil detector ( Mainly Cherenkov )

• Ring imaging Cherenkov detectorLarge fiducial volume High efficiency for low momentum 0

Threshold for protons are so high. ( ~ GeV/c )

• SciFi Water target tracking detector. Passive ( non-active ) volume is fairly large

pions/protons stop in the passive region.

High statistics & precise measurement is very important.

FNAL 8GeV Booster neutrino beam line

4.Existing neutrino beam line

: 92.9 % 6.5 %e: 0.6 %e: 0.05%

Neutrino beam flux @ SciBooNE hall (Neutrino flux) x (cross-section)

Mean E 1.1 GeVPeak E 0.8 GeV

Intense low energy neutrino beamMean energy of neutrino flux 0.7GeV ( peak at 0.6GeV )

Averaged r<2m

~83% ~16%e ~0.2%e ~0.4%

4. Existing neutrino beam lineFNAL 8GeV Booster neutrino beam line

Possible to deliver both neutrino and anti-neutrino beams.

Mean E0.6 GeV ( Peak E0.45 GeV )

Anti neutrino beam flux @ SciBooNE hall

There are only a few low energy anti-neutrino data available.

1 2

Average energy :1.0GeV ( + )0.9GeV ( only)

~63% ~36%e ~0.4%e ~0.6%

20.5 1.51 (GeV)(GeV)3

(Anti neutrino flux) x (cross-section)

E (GeV)

T2K

K2K

SciBooNE

Flu

x (n

orm

aliz

ed

by

are

a)

0.5 1 1.5 2

4. Existing neutrino beam lineFNAL 8GeV Booster neutrino beam line

Energy spectrum is quite similar to the T2K neutrino beam.Precise study of neutrino interactions with this beam is expected

to provide important information for the T2K experiment.

Full active scintillator detector similar to SciBar

will be used as a near detector of the T2K experiment.

FNAL 8GeV Booster delivers ~ 2 x 1020 protons to the target

in a year of running.

5. SciBooNE ExperimentBring the K2K-SciBar detector

to the FNAL Booster neutrino beamline

Fer

mila

b V

isua

l Med

ia S

ervi

ces

SciBooNEDetector

Booster

Target & Horn

5. Detectors of the SciBooNE experimentMuon RangeDetector (MRD)

Electron Catcher (EC)

SciBar

beam

1) SciBar detector Neutrino interaction target Tracking detector2) Electron catcher Spaghetti calorimeter Lead as converter3) Muon range detector Sampling calorimeter Measure muon momentum

Extrudedscintillator(15t)

Multi-anodePMT (64 ch.)

Wave-length shifting fiber

1.7m

3m

3m

• High efficiency even for the short tracks• Can identify low momentum protons

above ~ 450 MeV/c.• PID (p/) & momentum measurement by dE/dx.

• Full Active tracking detector Extruded scintillator

with WLS fiber readout Cell size : 2.5 x 1.3 x 300cm3

Light yield :7~20p.e. /MIP/cm (2 MeV)

reconstruct vertex identify the interaction

5. The SciBar detector

4 cm8 cm

262 cm

Readout Cell

Fibers

5. The Electron Catcher“spaghetti” calorimeter used in CHORUS

• 1mm diameter fibers in the grooves of lead foils

• Each 4 x 4cm2 cell is read outfrom both e

nds• 2 planes (11X0) Horizontal: 32 modules Vertical : 32 modules

Total 256 readout channels

• Expected energy resolution

14%/√E

Beam

PMTs

5. Muon Range Detector (MRD)

MRD built with used scintillators, iron plates and PMTsto measure the muon momentum up to 1.2 GeV/c.

• Iron Plates305 x 274 x 5 cm3

Total 12 layers

• Scintillator PlanesAlternating horizontal

and vertical planes.

Total 362 channels.

# of events[/10tons/1E20POT]

Fraction

CC-QE 41,100 41.0%

CC-1pi 23,500 23.5%

CC-coherent 1,500 1.5%

CC-other 5,500 5.5%

NC-1pi 8,500 8.5%

NC-coherent 900 0.9%

NC-other 1,700 1.7%

NC-elastic 17,400 17.4%

6. Expected interaction rates ( neutrino mode )

Beam time June 2007 ~ Summer 2008.Protons on target 1 x 1020 for neutrino

1 x 1020 for anti neutrino

DIS etc. Small fraction

Dominant

Neutrino interaction studies at SciBooNE1. quasi-elastic scattering (+ n -> +p)

p

Real event in K2K

• 2 tracks 1 MIP and 1 large dE/dx tracks

• Dominant interaction mode41K events (41%)

• Basically 2 body interactionIncoming direction is fixed.

Expected direction of proton is calculated from observed .

Real SciBooNE Data

No data

Real SciBooNE Data

Free proton scattering check of nuclear model

Expect ~9,000 CCQE eventsafter cuts, 80% purity

Neutrino interaction studies at SciBooNE2. quasi-elastic scattering ( + p -> + n )

Detected as a 1-track eventin SciBar

Excellent energy and q2 resolution

anti- CC-QE candidate(+ p + n)

Dominant background for disappearance

(sin2 2) (m2)

Neutrino interaction studies at SciBooNE3. Single production ( + n -> + p + + etc )

disappearance measurement error (90%CL)

stat. only (nQE/QE)= 5% (nQE/QE)=20%

pp

At BNB energies

Second dominant : CC1p+T2K needs to reduce uncertainty

of non-QE/QE ratio Currently ~20% Try to reduce less

than 10%.

pp

pp

Statistics : Sufficient for ~ 5% measurement

Vertex activity cuts separate +pp+

from +nn+

Neutrino interaction studies at SciBooNE3. CC Single production ( + n -> + p + + etc )

3 tracks 2 MIPs 1 large dE/dx

2 tracks 2 MIPs

2 tracks 1 MIP 1 large dE/dx

Expect ~2,800 CC-1+ events after cuts

• Dominant background to e appearance • For the 1st phase of T2K,

need to reduce systematic error down to ~10%.

1 2 3 4 5

Exposure /(22.5kt x yr)

10-2

- stat. only- BG=10%- BG=20%

sin

2 2

13 s

en

sit

ivit

y

Neutrino interaction studies at SciBooNE4. NC Single production ( + n -> + p + + etc )

T2K e appearancesensitivity plot

Projected SciBar at K2K

Projected SciBar at BooNE

(+p+p+0)

Timeline of the SciBooNE experiment

2005 Summer Collaboration formed2005 Dec. Proposal2006 Jul. Detectors move to FNAL2006 Sep. Groundbreaking2006 Nov. EC assembly2007 Feb. SciBar assembly2007 Mar. MRD assembly2007 Mar. Cosmic ray data taking2007 Apr. Detector installation2007 May. Commissioning2007 Jun. Anti-neutrino beam run start2008 Oct. Neutrino beam run start2009 Apr.(?) Anti-neutrino beam run start2009 July.(?) End of the data taking start

In total ~ 1 year of data taking

Delivered POT: 5.45x1019

Analyzed POT : 4.3x1019

mode ( June ~ Aug. 2007 ) mode ( Oct. 2007 ~ )

Accumulated POT ( June 2007 ~ Dec. 2007 )

Detector live time fraction ~95%

More than 3 hits in each view Threshold: 2 p.e

Track length > 4 layers

Vertex in fiducial volume -130cm<x<130cm

-130cm<y<130cm

2.62cm<z<157.2cm (2nd~60th layer)

Require hit in the most downstream layer

Within 2sec on-timing window

vertex

Fiducial volume

SciBar detector

Longesttrack

SciBar event selection criteria for the event rate and the other basic studies

Scintillator Iron plate

beam

vetoRequire at least 4 planes

Fiducial Volume(9 iron planes)

muon

-132cm < X < 132cm-110cm < Y < 110cm9 iron planes(thickness of 1plane ~2inch)

FV mass ~ 21.1ton

• Fiducial Volume

• TimingCluster within 2sec time window is selected

• ReconstructionHits on 4 scintillator planes are required ( 2vertical, 2horizontal)

MRD event selection criteria for the event rate and the other basic studies

Event displaysTOP view SIDE view

Real SciBooNE Data

3-track event

+/-10%

CC candidate events in SciBar ~ 5000 events

(FV ~10.6 tons)

VERY PRELIMINARY

Event rate ( Summer 2007 anti-neutrino run )Period: Jun. 12 - Jul. 28

6/16 6/23 6/30 7/ 7 7/14 7/21 7/286/19

CC candidate events in SciBar

CC candidate events in MRD~10000 events

(FV~19 tons)VERY PRELIMINARY

CC candidate events in MRD

+/-10%

6/16 6/23 6/30 7/ 7 7/14 7/216/19

PRELIMINARY2 / ndf = 7.591 / 7

Event rate ( Autumn 2007 neutrino run )

2 / ndf = 15.4 / 7

PRELIMINARY

CC candidate events in MRD~ 50000 events

(FV~21 tons)

Oct.20 Nov.03 Nov.17 Dec.01 Oct.27 Nov.10 Nov.24 Dec.8

CC candidate events in SciBar~ 20000 events

(FV~10 tons)

CC candidate events in SciBar CC candidate events in MRD

Oct.20 Nov.03 Nov.17 Dec.01 Oct.27 Nov.10 Nov.24 Dec.8

Summary

SciBooNE experiment will provide high statistics and high precision neutrino interaction data.

Data taking was started in June 2007.Summer 2007

Anti neutrino run ~ 5 x 1019 POTAutumn 2007

Neutrino run ~ 5 x 1019 POT

Data taking will complete in Summer 2008.

Neutrino interaction measurement CC 1 + productionNC 0 production

~ 10% precision