accelerator neutrino experiments

Accelerator neutrino experiments

Jennifer ThomasUniversity College London

Thanks to s.brice, p.vahle, d.wark

J.Thomas Lepton-Photon 2007 2

Accelerator neutrino experiments

Direct observation of tau neutrinos DoNUT

Present neutrino oscillation resultsk2k, minos, opera, (lsnd,mini-boone)

Plans for next generation long baseline experiments

Experiments of general interestCross sections : sci-boone, minerva

t2k, nova

conclusion


Neutrino sector status (2007)

23 2

1iα/2

2iα/

iδ13 13

-iδ13

3

23 2 13

12 12

12 122+iβ

μ

τ

e

3 3

c 0 s1 0 0

0 c

1 0 0 ν

= 0 e

e

0 1 0

-s e

c s 0

-s c 0

0

0 ν

0 0

s

0 -0 0s c νc eν

ν

ν

1

Inverted hierarchy3light neutrino flavours: e,

m221 : (7.0 - 9.1) × 10-5 eV2

TAN212 : 0.34 – 0.62

m232 : (2.2 – 2.58) × 10-3 eV2

sin223 : 0.31 – 0.71

SIN213 ≤ 0.045 : unknownHierarchy : unknown

mlightest < 2.2 eVDirac or Majorana: unknown

[updated from Gonzalez-Garcia PASI 2006]

m232

m221

(m3)2

(m2)2

(m1)2

Normal hierarchy

m221

(m2)2

(m1)2

(m3)2

m231

e

m2lightest m2

lightest


Analysis complete – 9 found in 578 total Background ~1.5 events (charm + hadronic int)Preliminary x-section results (cc) X relative to e for energy-indpdt part

DONuT: Direct Observation of

e 1.14 0.45

1.230.44

Proof of principle for operaX


2-3 long baseline concept

iδe 12 12 13 13 1

iα/2μ 12 12 2

-iδ iα/22

+iβτ 1

3 23

23 23 3 13 3

ν c s 0 c 0 s1 0 0

0 c s

0

e 1 0 0 ν

ν = -s c 0 0 1 0 0 e 0 ν

ν 0 -s c0 1 -s e 0 c 0 0 e ν

ν ν 22

21 ssin inm L

PE

θΔ

μ μ

Monte Carlo

Spectrum ratio

m232

m221

(m3)2

(m2)2

(m1)2

m221

(m2)2

(m1)2

(m3)2

m231

e

m2lightest m2

lightest

UnoscillatedOscillated

νμ spectrumMonte Carlo


K2K: 1st long baseline experiment

L/E=0.25Km/MeV

58 single-ring -like evts

Phys.Rev.D 74, 072003,2006

Confirmation of sk result

300m near detector

250km baseline

SuperK far detector

112 observed cc

158.1 expected


MINOS: 2-3 sector precision measurement

Far detector

Near detector

Far Detector:Soudan, Minnesota 5.4 kton mass484 steel/sci planes8x8x30 m3

2.3% absolute calibrationB-field~1.3T

Near Detector:Fermilab, Illinois1km from target1 kton mass282 steel planes3.1% absolute calibration153 scintillator planes, 3.8x4.8x15 m3

Bfield~1.3T

735 km baseline

l/e=0.4km/mev


Neutrinos from the Main Injector (NuMI)

10 μs spill 120 GeV protons every 2.4s180 kW typical beam power2.5 1013 protons per pulseNeutrino spectrum changes with target and horn position

2.5e20 p.o.t.

Used in new analysis


MINOS: near detector exploitation

‘Identical’ Detectors ND and FD

Use ND spectra for:Beam MC tuning => flux measurementFD spectrum prediction takes advantage of all cancellations

Cross sectionDetector thresholdsSecondary hadron production (1st order)

Calorimeter Spectrometer

Fiducial Volume


MINOS Beam MC tuning

Use different beam configurations to learn about beamDiscrepancies in different places pointed to beam issuesParameterize Fluka2005 hadron productionre-weight as f(xF,pT)

Horn focusing, beam misalignments, neutrino energy scale, cross section, NC background

Weights applied vs pz & pT


minos near detector cc selection Particle IDentification Distribution

CC

-lik

e

NC-like

All Energies

Finding muons is main approachSelect cc events with pdf based on 6 parameters reflecting confidence in event’s track like characteristics


MINOS FD Spectrum Prediction

Measured ND spectrum is transported to FDEfd is not just End/r2

Pion/Kaon decay kinematics encapsulated in matrix

MC to provide corrections (resolution, acceptance)

x =

Hadron production changes are 2nd order : affects ND and FD together

)27.1(sin)2(sin)( 222EL

x mP

6.2 effect <10GeV


Sector 2-3 allowed parameter space

08.0232 00.12sin

08.0232

2320.016.0

232

00.12sin

eV 1038.2

m

Statistics limited


MC

MINOS MC

MINOS Outlook

Muon neutrino disappearance6e20 pot by end 2008

Anti-neutrino oscillationsin neutrino beamanti- running > 09

Electron neutrino appearance by end 2007Search for exotics

Sterile neutrinosNeutrino decay/de-coh


Opera : appearance of tau neutrinos

spectrometer: Dipolar magnet + RPC chambers

Physics goals:Verify oscillation is to Search for e appearance

cngs L/e = 0.04km/MeV (17GeV E)

12 events expected, 1 bkg, after 5 yrsMay 07 cosmic test:

Prediction, extraction, scanningTurn on sep 07 50-60kbricksFull compliment mar 08

Pb

1 mm

Emulsion Cloud Chamber


Future long baseline : goals e

e 12 12 1iα/2

μ 12 12 23 2

iδ13 13

-iδ13 13

3 2iα/2+iβ

τ 23 23 3

c 0 sν c s 0 1 0 0 1 0 0 ν

ν = -s c 0 0 c s 0 e 0 ν

ν 0 0 1 0 -s c 0 0

e

0 1 0

-s e 0 c e ν

sin213

10-3

10-2

m2

31 [

eV

2]

high precision 2-3 parameters

observation of e events

13 : present sin213<0.04

cp violation

mass hierarchy

Schwetz hep/ph 0606060

m232

m221

(m3)2

(m2)2

(m1)2

m221

(m2)2

(m1)2

(m3)2

m231

e

m2lightest m2

lightest


12 21

12

3123 31

31

23

3123 32 31

31

32

22 2 2

2

22

21

12

2 22

3 32

13

13

13

sin ( )( ) sin sin 2

( )

sin ( )cos sin 2

( )

sin( ) sin( )cos sin 2 sin 2 sin 2 cos

( ) ( )

sin(sin sin 2 sin 2 sin 2 sin

e

aLP

aL

aL

aL

aL aL

aL aL

131 1

312

) sin( )

( ) ( )

aL aL

aL aL

1/ 2 (4000 km)F ea G N 21.27 /ij ijm L E

L(km), E(GeV), m(eV)

Future long baseline: goals

Measure 13

present limit:Sin2213<0.15

Sin213<0.04

Sin13<0.2

13<11.5o

Second experiment with different l (or E) will give complimentary information for mass hierarchy

CP violation and matter effects are ambiguous for half possible values of

Patmos

Psolar

interference

e

ee

e


Future long baseline: tools

TargetHornsDecay Pipe

FarDetectorNear

Detector

Reduces high energy tail and so NC 0 backgroundReduces e contamination from K and decay due to decay kinematics

Off axis beams

High granularity detector in NuMI beamline : good for noa

wide scope : several z x-sec measurements at a few GeV

X-sec measurements: Minera and sci-boone

K2K SciBar detector in the FNAL Booster Neutrino Beamline

Precision measurement of x-secs for T2k : beam well matched

e/gev


NOAFar detector:

14 kton, fully active segmented 14.5 mrad off NuMI beamline axis810 km baseline, E~2gev, l/e=0.4km/mev

Near DetectorFunctionally same as FDWill move to sample different backgrounds

opticalfibre


Noa: future reach

Matter effects increase (decrease) oscillations for normal (inverted) hierarchy for Hierarchy can be resolved if 13 near to present limit

Nova has longest baseline: 810km

run with and

Matter effect in


T2K: jparc to Super-K

Near Det @ 280m 2.5mrad(off-axis)Inside ua1/nomad magnet for momentum measurementSandwich calorimeters/tracker for precision beam measurementE~0.8GeV, l/e=0.4km/mev

0 from neutral current interactions important background

Ingrid detector @ 280m (on-axis)Iron scintillator trackerDetermines beam profile and direction


T2K: Sensitivity

Plot from I. Kato/T2K


T2k and noa: latest

T2K:Hoping for first data April 2009Ramp up to 750kW source by 2012

Nova:Hoping to start detector construction in 2010 and have 700kW source on same timescale

50

30

20

50

30

20

Mezzetto

Many inponderables

Reasonable assumptions


conclusions

A decade of discovery has produced 5 effective parameters: sin223,tan12,|m2

23|,m221 and its

sign

Lessons learned for the futureNear detector ….is your best friend!Beam flexibility….is next

Still to be determined: 13, sign (m223), CP

Maybe CP , m223 within reach of next

experiments if sin22 >0.01

Point is to find an underlying symmetry: focus on precision measurements of parameters

Near detectorsOff axis beams and flexibilityCross sectionsDetector precision


BACKUP SLIDES


MINOS Near Detector: Particle IDentification Input Variables


What Changed?

Data sets:•Pre-shutdown•Post-shutdown

Improvements:•reco & selection•shower modelling


NuMI AlignmentAlign the center of beam to the Far Detector in the

Soudan mine. Goal is within 12 m.

• Fermilab to Soudan surface done using GPS

• determined vector to 0.01 m horiz., 0.06 m vertical

• Soudan surface to 27th level

• 0.7 m per coordinate

• Fermilab surface to underground

• gyrotheodolite with 0.015 mrad precision

• 11 m at Soudan

• Transverse alignment of baffle, target and horn at 0.5 mm


Event generatorNeutrino-nucleus interactions were generated using the NEUGEN3 neutrino event generator (H. Gallagher, Nucl.Phys.Proc.Suppl. 112: 188-194, 2002)

Quasi-Elastic: dipole parametrization of form factors with ma=0.99 GeV/c2 (BBBA05 Bradford et al. Nucl.Phys.Proc.Suppl.159:127-132,2006)

Resonance Production: Rein-Seghal model for W<1.7 GeV/c2. (Annals Phys. 133: 79, 1981)

DIS: Bodek-Yang modified LO model. For W<1.7 GeV tuned to electron and neutrino data in the resonance / DIS overlap region.(Bodek-Yang, Nucl. Phys. Proc. Suppl. 139: 113-118, 2005 and H. Gallagher, NuINT05 Proceedings)

Coherent Production: Rein-Seghal (Nucl. Phys. B 223: 29, 1983)


Beam Matrix Prediction & Near Detector Data : RunI/RunIIa


Using Beam Matrix Method, hadron production tuning does not affect the Unoscillated prediction (obtained from the ND data) by more than 1-2%.

However, its use improves the MC (make it more similar to the data) and therefore uncertainties due to energy smearing-unsmearing and acceptance become smaller.

Effect of MC tuning on the measurement

Ratio of Far Prediction using the Beam Matrix and with/without hadron production tuning

Far Predicted Spectra using the Beam Matrix and with/without hadron production tuningUsing tuned MC for

energy smearing and acceptance corrections

Using nominal MC for energy smearing and acceptance corrections

Using tuned MC for energy smearing and acceptance corrections

Using nominal MC for energy smearing and acceptance corrections


MINOS: new analysis 2007

New PID has higher overall efficiency and higher background rejection (less contamination from NC interactions)


MINOS: Near Detector Data/MC

Track Angles (X Y Z)

normalized to area Event Vertices (X Y Z)


UncertaintyShift in m2

(10-3 eV2)Shift in sin2(2

Near/Far normalization 4% 0.065 <0.005

Absolute hadronic energy scale 10% 0.075 <0.005

NC contamination 50% 0.010 0.008

All other systematic uncertainties 0.041 <0.005

Total systematic (in quadrature) 0.11 0.008

Statistical error (data) 0.17 0.080

The main remaining systematic uncertainties are Near/Far normalization, absolute hadronic energy scale and NC contaminationOverall systematics reduced by use of near detector

MINOS: systematic uncertainties


For energies between 0-10 GeV a deficit of 38% is observed, with respect to the no disappearance hypothesis.

0.57 (6.5 350 14198CClike (<5 GeV)

0.62 (6.2 ) 496 20310 CClike (<10 GeV)

0.76 (4.4 )738 30563CClike All

Data/Prediction

Expected( Unoscillated)

FDData

Data Sample


MINOS Detector Technology

Near and Far Detectors are functionally identical:

2.54cm thick 1.3 T magnetised steel plates

co-extruded scintillator strips

orthogonal orientation on alternate planes – U,V

optical fibre readout to multi-anode PMTs

Multi-anode PMT

ExtrudedPS scint.4.1 x 1 cm

WLS fiber

ClearFiber cables

2.54 cm Fe

U V planes+/- 450

Scintillator strip M16 PMT


LSND result

Excess of e events in a beam

87.9 ± 22.4 ± 6.0 over background

~4 evidence for oscillation

m2 different from the solar and atmospheric m2s.With 3 standard model neutrinos 2 independent m2scould lsnd result be evidence for a sterile neutrino?

Mini-boone sees no excess in e l/e=0.001kev/km L/E=0.001km/MeV


0-3 GeV

3-6 GeV


After 13

Much information within :± m2,matter effect

Effects are non-trivial to disentangle

Complimentarity with different L,E and production

L=735km

pro

babili

ty

P ~ (Patmos)1/2 + (Psolar)1/2 + interference terms

E (GeV)


MINOS NC analysis : near detector Spectra

Search for sterile MC error band beam, cross-section and energy scale uncertainties

Fogli et al. 3+1 model


MINOS: e appearance status

Using full power of the near detectorComparison of mc/data shows discrepencySame effect in muon removed cc sample points to shower modellingBkgd spectrum will be derived from nd data

n

Hadronic

shower


Future long baseline: tools

Compilation of CC Quasi-Elastic x-Section Measurements

x-sec measurements : basic foundation of probes

CCQE x-sec is best known

search for tiny signals: background estimate is paramount

eg: high y cc events which oscillate cannot be estimated in near detector

2 experiments being mounted to address these issues


MINOS: measurement vs prediction

Oscillation Hypothesis best fit

No Disappearance Hypothesis

P(2,n.d.f) = 0.18

2 /n.d.f = 41.2/34 = 1.2

2 /n.d.f = 139.2/36 =3.9

P(2,n.d.f) = 0.18

)27.1(sin)2(sin)( 222EL

x mP

6.2 effect below 10GeV

accelerator neutrino experiments

Documents

thomas leptonphoton

neutrino sector status

neutrino energy scale

tnear detector

beam misalignments

long baseline conceptj

typical beam power2

main approachselect