measurements of neutrino charged current scattering in k2k fine-grained detector

Measurements of Measurements of neutrino charged current scattering neutrino charged current scattering

in K2K Fine-Grained Detector in K2K Fine-Grained Detector

IntroductionIntroduction K2K Near DetectorK2K Near Detector CC interactions (CC interactions (ppQQ22)) Summary Summary

M.Hasegawa Kyoto UniversityM.Hasegawa Kyoto University for the K2K collaborationfor the K2K collaboration

Charged Current ScatteringCharged Current Scattering

Kyoto Univ Masaya Hasegawa NuFact 04 July. 26 – Aug. 1 , 2004 Osaka Univ.

Charged Current Quasi-Elastic (CCQE) Scattering

- Dominant process around 1GeV (~40% of CC)- E can be reconstructed from (pp )

Charged Current non Quasi-Elastic (nonQE) Scattering

- single production (CC1) (~38% of CC) - multi production (CCm(~18% of CC)- Coherent production (~2% of CC)

Coherent production

K2K Charged Current AnalysisK2K Charged Current Analysis


… …

1kt data (for example)

(

deg

.)

p (MeV/c)0

20

40

60

500 1000

Data(P, ) = F(i) * [ CCQE + RnQE/QE * nQE ] F(i) : Neutrino flux (i =1~7)

RnQE/QE : NonQE to QE ratio

Main motivation is to determine E spectrum @near siteLatest result in Maesaka’s(Kyoto)talk (WG1 in this morning)

CC Analysis - cont’dCC Analysis - cont’d


Another Motivation is to study the int. in a few GeV region.

CCQE , CC1 Form factors CC1) / CCQE), CC multi ) / CCQE) LowQ2 (CC1 , Coherent

(Important to understand Background for CCQE)

K2K measures (On-Going Work)

B.G. from non-QE

E (near vs Far)

K2K Near Detectors K2K Near Detectors


1kt Water Cherencov detector (1kt) Scintillating Fiber Detector (Scifi) Scintillator Bar Detector (SciBar) (2003-) Muon Range Detector (MRD)

K2K Near Detectors

Neutrino beam properties at production.

Neutrino interactions <E> ~ 1.3GeV

K2K-II Detectors (2003-)

Study int.

Scifi DetectorScifi Detector


SciScintillating FiFiber sheet / Water Sandwich detector

Track Finding Efficiency ~93% (single track)Tracking threshold 3layer(>12cm) (=Proton 0.60GeV/c)

260cm 173cm

260cm

Possible to identify CCQE events by using Proton track

SciBar DetectorSciBar Detector


Extrudedscintillator(15t)

Multi-anodePMT (64 ch)

Wave-lengthshifting fiber

EM calorim

eter

1.7m

3m

3m

Neutrino target is scintillator itself

2.5 x 1.3 x 300 cm3 cell (15000ch)

(Fairly) large volume (10000 int. / month)

Just constructed in last summer!

Fine segmented , Full Active SciScintillator-Bar Bar Tracker

Tracking Threshold : 8cm (=0.4GeV/c Proton)

Track-finding efficiency >99% (Single Track) Excellent p/using dE/dx misID( P) = 1.7% @ PEff=90%

High 2-track CC-QE efficiency

Identify ν interaction mode clearly

Prelim

inar

y

Prelim

inar

y

SciBar Shot !SciBar Shot !


p

CCQE candidateCCQE candidate

1

23

CCnQE candidateCCnQE candidate

FGD Charged Current Analysis FGD Charged Current Analysis


Vertex

MRD(Iron plates and drift tubes)SciBar

Selection

Use events which have more than 1 track connected with MRD ( CC fraction ~100%(Scifi) , ~ 98% (SciBar) )

Scifi SciBar MRD


QE/nQE

QE nonQE

DATACC QECC 1CC coherent-CC multi-

p

(deg)

(1) 1 Track 60% QE (2) 2 Track QE enriched 60%(SF) / 70%(SB) QE (3) 2 Track nonQE enriched 85% nQE

Expected proton direction assuming CCQE

p

Observed second track

SciBar p

Use proton track direction to enhance CCQE / non QE

SciBar 1Track Sample


p


q2(rec)

Agreement is good exceptfor lowQ2(forward) region.

MC (NEUT4.5) Nucl.Phys.Proc.112,171

- MA(QE) = MA(1) = 1.1GeV/c2

- Marteau model (coherent ) - Bodek/Yang (DIS)

SciBar 2Track QE sample



p

Good Agreement(No deficit can be found)

q2(rec)

SciBar 2Track nQE sample



p

Agreement is good exceptfor lowQ2(forward) region.

Clear deficit can be seen.

q2(rec)

1Kt , Scifi Q2 distribution


1 Kt 1ring muon-like event

(GeV2)

From SciBar (&Scifi) result , source is nonQE. (CC1 or coherent cross section is suspicious )

Scifi 2track nonQE enriched event


Three detectors see the same effect. This cannot be explained by detector systematics.

CC1CC1 suppressing vs No coherent suppressing vs No coherent


LowQ2 suppression in CC1QQ No coherent

Currently, we don’t judge which is source of low Q2 deficit.

SB Coherent SB Coherent Analysis (On- Analysis (On-going)going)


N

CC1Coherent

No activity around Vertex (Full Active) Hadron track is Pion ( PID )

SciBar can separate them effectively. 　　　 And just working now

Difference between coherent and CC1

In the case of coherent

Summary


K2K Charged Current Analysis provide K2K Charged Current Analysis provide Neutrino Flux & Knowledge of Neutrino Flux & Knowledge of int (~1.3GeV).int (~1.3GeV).

New near detector ‘SciBar’ was installed in New near detector ‘SciBar’ was installed in last summer and works stably and showslast summer and works stably and shows good performance as expected. good performance as expected.

Muon distributions (Muon distributions (ppQQ22)) agreed with MCagreed with MC except for lowQexcept for lowQ22 region. (Origin is CC1 region. (Origin is CC1 or coherent or coherent or Both. Currently we doesn’t judge.) or Both. Currently we doesn’t judge.) SciBar Analysis will answer this question soon. SciBar Analysis will answer this question soon. stay tuned!stay tuned!

Supplement

A

A=0.10 +/– 0.03

CC1q2/0.10

(Data–MC)/MCAgree quite well

• By using SciBar 2track-nonQE and fitted flux, I looked for the best value of CC1 suppression.

• Suppression factorq2/A (q2>A)

• Scan A value and calculate 2 of distribution.

Calculate

2

SciBar 2track nonQECC1 suppression factor tuning

Basic Performance (Tracking) Basic Performance (Tracking)


Track Finding Efficiency (Single Track)Track Finding Efficiency (Single Track)

Efficiency : 99.2% (>4layer ~ 10cm)

in coming 10cm

SciBar

Track Finding Efficiency (2nd Track)Track Finding Efficiency (2nd Track)

True Length

Detected !

Efficiency:76.7% (>8Hits) Main contribution on ineff. Is overlapping will be improved to > 90% soon

Confirmed w/ eye Systematic error : +0.2 / -2.5 %

Basic Performance (PID)Basic Performance (PID)


Mu-like(purity ~ 99.6%)

Proton-like(purity 90%)

Range in SciBar (cm)

To

tal d

E (

MIP

s)

Range vs Total deposit energy

DATA

(2track QE sample)

Non Muon-Like Muon-Like

sample

protonsample

Proton Efficiency

Muon mis-ID

Preliminary

Preliminary

Preliminary

PreliminaryExcellent p/using dE/dx

When 90% proton eff. is required,Muon Miss ID probability is 1.7%

Muon C.L.

Basic Performance (Energy Response) Basic Performance (Energy Response)


Top view Side view

High Accuracy gain monitoring SystEmHigh Accuracy gain monitoring SystEm　　　　　　　　　　　　　　 (HASE moni) (HASE moni)

+5%

-5%

We use a penetrating muon (cosmic as a (strip to strip) relative energy calib. source. All PMT channel’s (~15000ch) gain aremonitored by LED based system.

- Relative energy scale is calibrated at 1.5% precision - response for dE/dx is stable within 1.0% for 4months

Basic Performance (Stability) Basic Performance (Stability)


Event rate

Date

Eve

nt r

ate

(/10

18P

OT

)Efficiency0.748

Overall int. detection efficiency : ~75% (MC) (w/ >30cm Track)

Event rate is stable for 4 months.　　

On-Going Analysis


MA Analysis(QE) (Scifi)

Coherent search (mainly SciBar)

This is the first measurement of MA with water target.

This is the first search in a few GeV region.

Preliminary

Preliminary

7.03.0

Observed.(CC)Observed.(CC)

(Nuint04 Minerva)

One Candidate of Origin of LowQ2(forward)Deficit

(Nuint04 R.Gran)

K2KK2K

SciBar DetectorSciBar Detector


Extrudedscintillator(15t)

Multi-anodePMT (64 ch)

Wave-lengthshifting fiber

EM calorim

eter

1.7m

3m

3m

Extruded scintillator

with WLS fiber readout

Neutrino target is scintillator itself

2.5 x 1.3 x 300 cm3 cell

~15000 channels• Detect from less than 10cm track • Distinguish proton from

pion by using dE/dx• (fairly) large volume High 2-track CC-QE efficiency Identify ν interaction mode clearly

Just constructed in last summer!

SciBar Charged Current Analysis SciBar Charged Current Analysis


Vertex

MRD(Iron plates and drift tubes)SciBar

Selection

Vertex

SciBar-MRD 3D Track Matching (pμ>0.5GeV/c)- 35% of All interaction ( CCQE fraction ~

SciBar-MRD 1L Stopping Event (pμ>0.3GeV/c) - 9% of All interaction ( CCQE fraction ~


• CC quasi elastic (CCQE)

– Smith and Moniz with MA=1.1GeV

• CC (resonance) single (CC-1)

– Rein and Sehgal’s with MA=1.1GeV

• DIS

– GRV94 + JETSET with Bodek and Yang correction.

• CC coherent – Rein&Sehgal with the cross secti

on rescale by J. Marteau

• NC

+ Nuclear Effects

/E (10-38cm2/GeV)

Total (NC+CC)

CC Total

CC quasi-elastic

DISCC single

NC single 0

E (GeV)

NEUT: K2K Neutrino interaction MC


P 1trk

P 2trkQE

P 2trknon-QE

1trk

2trkQE

2trknon-QE

0 2 (GeV/c) 0 40 (degree)

flux measurement

10

SciFi (K2K-IIa with measured spectrum)

P 1trk

P 2trk QE

P 2trk nQE

1trk

2trk QE

2trk nQE

flux measurement

10

SciBar (with measured flux)


K2K Charged Current AnalysisK2K Charged Current AnalysisMain motivation is to determine E spectrum @near site

Latest result in Maesaka’s(Kyoto)talk (WG1 in this morning)


cos

22

pEm

mEmE

N

N

K2K Charged Current AnalysisK2K Charged Current Analysis


… …

1kt data (for example)

(

deg

.)

p (MeV/c)0

20

40

60

500 1000

Data(P, ) = F(i) * [ CCQE + RnQE/QE * nQE ] F(i) : Neutrino flux (i =1~7)

RnQE/QE : NonQE to QE ratio

Main motivation is to determine E spectrum @near siteLatest result in Maesaka’s(Kyoto)talk (WG1 in this morning)

SB Coherent SB Coherent Analysis (On-goin Analysis (On-going)g)


Neutrino scatters coherently from the entire nucleuswith small energy transfer.

N

CC1Coherent

No activity around Vertex (Full Active) Hadron track is Pion ( PID )

SciBar can separate them effectively.

SciBarnon-QE Events

K2K observed forward deficit.– A source is non-QE events.

– For CC-1,

• Suppression of ~q2/0.1[GeV2] at q2<0.1[GeV2] may exist.

– For CC-coherent ,

• The coherent may not exist.

We do not identify which process causes the effect. The MC CC-1 (coherent ) model is corrected phenomenologically.

Oscillation analysis is insensitive to the choice.

q2rec

(Data-MC)/MC

DATACC 1CC coherent-

Preliminary

q2rec (GeV/c)2

q2rec (GeV/c)2

CC1 suppression

measurements of neutrino charged current scattering in k2k fine-grained detector

Documents

track qe

track nonqe

hasegawa kyoto university

cc coherent p production

qe scibar

single p production

detector cc interactions

ccqe events