[PPT] - Searching for sterile antineutrinos with SciBooNE & MiniBooNE PowerPoint Presentation

SLIDE 1

Joint Search for ν̅µ Disappearance at Δm2 ~1 eV2

Searching for sterile antineutrinos with SciBooNE & MiniBooNE

M.O. Wascko Imperial College London Birmingham HEP Seminar 2013 01 16

1 Wednesday, 16 January 13

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

Outline

Introduction
Neutrino oscillation
The LSND signal and sterile neutrinos
Experiments: SciBooNE and MiniBooNE
SciBooNE-MiniBooNE joint ν̅µ disappearance analysis
Results

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

Introduction

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

Neutrino oscillation

if neutrinos have mass...
a neutrino that is produced as a ν̅µ
(e.g. π− → µ− ν̅µ)
might some time later be observed as a ν̅e
(e.g. ν̅e n → e+ p)

ν µ e W W Source Detector

Maki, Nakagawa, Sakata

Prog.Theor.Phys. 28, 870 (1962)

Pontecorvo

Sov.Phys.JETP 6:429,1957 Sov.Phys.JETP 26:984-988,1968

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✓ νe νµ ◆ = ✓ cosθ sinθ −sinθ cosθ ◆✓ ν1 ν2 ◆

|νµ(t) > = −sinθ (|ν1 > e−iE1t)+cosθ (|ν2 > e−iE2t)

Poscillation(νµ → νe) = | < νe|νµ(t) > |2

The weak states are mixtures of the mass states: In a world with 2 neutrinos, if the weak eigenstates (νe, νµ) are different from the mass eigenstates (ν1, ν2): The probability to find a νe when you started with a νµ is:

|νµ > = −sinθ|ν1 > +cosθ|ν2 >

ν1 ν2 νe νµ ϴ

Neutrino oscillation

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Birmingham HEP Seminar

2 fundamental parameters
Δm2 ↔ period
θ12 ↔ magnitude
2 experimental parameters
L = distance travelled
E = neutrino energy
Choose L&E to target ranges of

Δm2 and θ

Neutrinos disappear and appear

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

2 fundamental parameters
Δm2 ↔ period
θ12 ↔ magnitude
2 experimental parameters
L = distance travelled
E = neutrino energy
Choose L&E to target ranges of

Δm2 and θ

Neutrinos disappear and appear

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

2 fundamental parameters
Δm2 ↔ period
θ12 ↔ magnitude
2 experimental parameters
L = distance travelled
E = neutrino energy
Choose L&E to target ranges of

Δm2 and θ

Neutrinos disappear and appear

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

L and E determine Δm2

sensitivity

θ12 sensitivity determined

by statistics, backgrounds, and uncertainties

No signal: exclusion

curve

Signal: allowed region

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

Neutrino Interactions

Z0 νµ νµ NC W+ νµ µ- CC

CC interactions preserve neutrino flavour, but require enough energy to produce rest mass of charged lepton! NC interactions can happen equally for all flavours because there is no energy requirement Both interaction modes are useful for neutrino

scillation experiments

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

Three flavours

flavour atmospheric cross-mixing solar mass where cij=cosθij, sij=sinθij Mass (eV) 0.05 0.009

ν3 ν2 ν1

solar atmospheric ?

νe νµ ντ

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Birmingham HEP Seminar

Atmospheric Oscillation

Super-K MINOS flavour atmospheric cross-mixing solar mass

Phys.Rev.Lett.81.1562(1998) PhysRevLett.101.131802

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Birmingham HEP Seminar

SNO KamLAND

Solar Oscillation

flavour atmospheric cross-mixing solar mass

Phys.Rev.Lett.89.011301 (2002) Phys.Rev.Lett.100.221803 (2008)

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Cross Mixing

10-2 Causes ν̅e disappearance in reactors and νe appearance in accelerator experiments flavour atmospheric cross-mixing solar mass

Phys.Rev.Lett.107.041801 (2011)

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

Current picture

flavour atmospheric cross-mixing solar mass Non-zero δ: matter vs antimatter where cij=cosθij, sij=sinθij Mass (eV) 0.05 0.009

ν3 ν2 ν1

solar atmospheric ?

νe νµ ντ

VALUE Δm223 Δm212 sin2θ12 sin2θ23 sin2θ13 δ 2.35E-03 (eV2) 7.58E-05 (eV2) 0.306 0.42 0.02 ?

arXiv:1106.6028 [hep-ph]

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

Open Questions

What is the value of θ13? δCP??
What is the mass hierarchy?
What is the absolute mass

scale?

What is the nature of neutrino

mass?

Dirac or Majorana?
Answers important for theories

about origins of neutrino mass

Relations to flavour? GUTs?
Cosmological and astrophysical

implications

Mass Quasi-Degenerate Mass Hierarchical Mass Normal Mass Inverted

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Birmingham HEP Seminar

The LSND Signal

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

The LSND Signal

The LSND experiment observed a small excess of ν̅e

events in a ν̅µ beam.

Phys.Rev.D 64, 112007 (2001)

Best fit: Δm2 ~ 1 eV2, sin22θ ~ 0.003 Data excess: 87.9 ± 22.4 ± 6.0 (3.8 σ)

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Sterile Neutrinos

LEP experiments

measured the number of light neutrinos: 3

Only two independent Δm2

values for 3 neutrinos

2.5☓10-3 + 7.6☓10-5 ≠ 1
LSND signal involves

sterile neutrinos, if it is due to neutrino oscillation

➡They do not interact via

the weak force

Phys.Lett.B 313 520 (1993)

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Active-sterile Neutrino Oscillation?

Sterile neutrinos could still mix with active neutrinos!

A simple realisation of the sterile neutrino is a right-handed neutrino νR , which can be mixed with active νL.

3+1 sterile neutrino scheme

3 4 m2

12

m2

23

m2

LSND

2

1 e s

µ
20

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

MiniBooNE νe Results

MiniBooNE recently tested the LSND signal.
Ruled out most of LSND region in νµ→ νe search.
However, observed (small) ν̅µ → ν̅e excess.
Consistent with LSND???
We want to test this with disappearance measurements!

) " (2

2

sin

3

10

2

10

1

10 1 )

4

/c

2

| (eV

2

m ! |

2

10

1

10 1 10

LSND 90% C.L. LSND 99% C.L.

2

10

1

10 1 10

y MiniBooNE 90% C.L. KARMEN2 90% C.L. Bugey 90% C.L.

νμ→ νe

Phys. Rev. Lett. 98, 231801(2007)

Null excluded at 99.4% with respect to the two neutrino E>475 MeV

ν̅μ→ν̅e

Phys.Rev.Lett. 105 181801(2010)

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

Indications of Sterile Neutrinos?

8 MiniBooNE Appearance arXiv:1207.4809 Red: Oscillations assuming 3 neutrino mixing Blue: Using a 3+1 (sterile neutrino) model

N.B.: several 2-3 σ results don’t constitute compelling evidence...

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Appearance vs. Disappearance

P (νµ → νx) = 1 − 4|Uµ4|2(1 − |Uµ4|2) sin2

1.27∆m2

41

L E ⇥

P (νe → νx) = 1 − 4|Ue4|2(1 − |Ue4|2) sin2

1.27∆m2

41

L E ⇥

P (νµ → νe) = 4|Ue4|2|Uµ4|2 sin2

1.27∆m2

41

L E ⇥

νµ→νe appearance νe disappearance νµ disappearance

νµ→νe appearance probability can be constrained by νe and νµ disappearance measurements!

Testing appearance signals with disappearance measurements

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar

Impact of Disappearance Experiments

νe disappearance νµ disappearance Compatibility of the existing measurements in (3+1) model νµ→νe appearance

(see also J. Kopp, M. Maltoni, T. Schwetz, arXiv:1103.4570)

Most of LSND region not compatible with disappearance results.
Disappearance measurement is a powerful tool!
C. Giunti, arXiv:1110.3914

sin22ee m41

2 [eV2]

102 101 1 102 101 1 10

99% C.L. Bugey−3 (1995) Bugey−4 (1994) + Rovno (1991) Gosgen (1986) + ILL (1995) Krasnoyarsk (1994) 99% C.L. Bugey−3 (1995) Bugey−4 (1994) + Rovno (1991) Gosgen (1986) + ILL (1995) Krasnoyarsk (1994)

sin22eµ m41

2 [eV2]

104 103 102 101 1 102 101 1 10

99% C.L. Reactors CDHSW + Atm Disappearance LSND + MB 99% C.L. Reactors CDHSW + Atm Disappearance LSND + MB

sin22µµ m41

2 [eV2]

102 101 1 102 101 1 10

99% C.L. CDHSW (1984): µ ATM: µ + µ 99% C.L. CDHSW (1984): µ ATM: µ + µ

sin22θee sin22θµµ sin22θµe

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Birmingham HEP Seminar

Other Scenarios

3+2 sterile neutrino mixing
Sterile neutrinos in extra

dimensions

Decaying sterile neutrino
CPT violation

Disappearance measurements can constrain these models.

PRD 72, 095017 (2005) JHEP 09, 048 (2005) PRD 77, 033001 (2008) PRD 76, 093005 (2007) PRD 80, 073001 (2009) arXiv:1103.4570 Allowed region in 3+2 model

★ ★

0.1 1 10 Δm

2 41

0.1 1 10 Δm

2 51

0.1 1 10 0.1 1 10

90%, 95%, 99%, 99.73% CL (2 dof)

3+2 1+3+1

J. Kopp, M. Maltoni, T. Schwetz, arXiv:1103.4570

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Imperial College London Morgan O. Wascko

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νµ Disappearance Measurements

Important to independently test νµ

and ν̅µ disappearance.

Testing CPT-invariance.
Recently, MiniBooNE searched for

νµ and ν̅µ disappearance with MiniBooNE data only (PRL 103, 0611802)

That analysis used the flux shape
nly, and suffered from large flux

and cross section uncertainties.

Improve with near detector

constraints!

1

1 10

2

10

90%CL excluded, CDHS 90%CL excluded, CCFR

1

1 10

2

10

90%CL excluded, CDHS 90%CL excluded, CCFR

1

1 10

2

10

90%CL excluded, CDHS 90%CL excluded, CCFR

1

1 10

2

10

90%CL excluded, CDHS 90%CL excluded, CCFR 90% C.L. sensitivity

µ

ν MiniBooNE 90% C.L. limit

µ

ν MiniBooNE (null) of 17.78

2

χ

f 12.72,

2

χ best fit: (17.50, 0.16) with

2

eV

2

m ∆

2

10

1

10 1

1

10 1 10 10

90%CL excluded, CCFR __ __ ) θ (2

2

sin

2

eV

2

m ∆

2

10

1

10 1

1

10 1 10 10

90%CL excluded, CCFR __ __ ) θ (2

2

sin

2

eV

2

m ∆

2

10

1

10 1

1

10 1 10 10

90%CL excluded, CCFR __ __ ) θ (2

2

sin

2

eV

2

m ∆

2

10

1

10 1

1

10 1 10 10

90%CL excluded, CCFR __ __ ) θ (2

2

sin

2

eV

2

m ∆ 90% C.L. sensitivity

µ

ν MiniBooNE 90% C.L. limit

µ

ν MiniBooNE (null) of 10.29

2

χ

f 5.43,

2

χ best fit: (31.30, 0.96) with

νµ disappearance

ν̅µ disappearance

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Birmingham HEP Seminar

Important to independently test νµ

and ν̅µ disappearance.

Testing CPT-invariance.
SciBooNE and MiniBooNE have

already produced a joint νµ disappearance result

World’s strongest limit at

10 < Δm2 < 30 eV2

2

2

sin 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 ]

2

[eV

2

m

1

10 1 10

90% CL limits from previous exp’s. 90% CL sensitivity (Sim. fit) 90% CL limit (Sim. fit) 90% CL limit (Spec. fit)

νµ Disappearance Measurements

νµ disappearance

arXiv:1106.5685[hep-ex]

Phys. Rev. D 85 032007 (2012)

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Birmingham HEP Seminar

Experiments

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Overview

50 m 100 m 440 m MiniBooNE Detector

Decay region

SciBooNE Detector Target/Horn

Fermilab visual media service

SciBooNE (2007-8) MiniBooNE (2002-present) 8GeV Booster Target/Horn

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Overview

MiniBooNE is designed to test the LSND signal
LSND L/E: 20m/30MeV ~ 0.7 meter/MeV
MiniBooNE L/E: 540m / 0.8 GeV ~ 0.7 m/MeV
SciBooNE (2007-2008) has two purposes
Precise measurement of neutrino cross section for future
scillation experiments (T2K, etc)
MiniBooNE near detector

50 m 100 m 440 m MiniBooNE Detector

Decay region

SciBooNE Detector Target/Horn

Common beamline Common neutrino target (both carbon) Significant reduction of systematic errors +

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!

E 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

1

25 MeV) × POT ×

2

Flux (cm

14

10

13

10

12

10

11

10

10

10

all

e

!

e

!

µ

!

µ

!

Fermilab Booster ν Beam

Intense ν̅µ beam with the mean

energy of ~0.6 GeV

93% pure muon flavour beam.
WS BGs need to be

constrained

νµ beam is also produced by

inverting horn polarity.

π− 50m decay volume Be target and horn soil νµ µ− 8 GeV proton Flux at SciBooNE

(similar to MiniBooNE)

Phys.Rev.D79,072002(2009)

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Pseudo-Feynman diagrams of neutrino interactions

Neutrino Interactions

νl

p

Z π+ Δ++

p

π0 Δ+ Z νl

p

CC / NC quasi-elastic scattering (QE) 42% / 16% CC / NC resonance production (1π) 25% / 7% Neutrino interaction data before oscillation era

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Neutrino Event Generation

CC/NC-1π

Quasi-Elastic
Llewellyn Smith, Smith-Moniz
MA=1.2GeV/c2
PF=217MeV/c, EB=27MeV

(for Carbon)

Resonant π
Rein-Sehgal (2007)
MA=1.2 GeV/c2
Coherent π
Rein-Sehgal (2006)
MA=1.0 GeV/c2
Deep Inelastic Scattering
GRV98 PDF
Bodek-Yang correction
Intra-nucleus interactions

Use two event generators: NEUT and NUANCE

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Birmingham HEP Seminar

SciBooNE Collaboration

Universitat Autonoma de Barcelona University of Cincinnati University of Colorado, Boulder Columbia University Fermi National Accelerator Laboratory High Energy Accelerator Research Organization (KEK) Imperial College London Indiana University Institute for Cosmic Ray Research (ICRR) Kyoto University Los Alamos National Laboratory Louisiana State University Massachusetts Institute of Technology Purdue University Calumet Universita degli Studi di Roma "La Sapienza“ and INFN Saint Mary's University of Minnesota Tokyo Institute of Technology Unversidad de Valencia

Spokespersons: M.O. Wascko (Imperial), T. Nakaya (Kyoto)

63 physicists 5 countries 18 institutions

SciBooNE, 2008

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Birmingham HEP Seminar

SciBooNE detector

Located 100 m from target.
SciBar:
Fully active scintillator tracker

(~14000 strips)

Neutrino target (~10 ton)
Main component： CH
Muon Range Detector (MRD)
Sandwich type detector of

steel + plastic scintillator.

Reconstruct muon energy

from path-length Muon Range Detector (MRD) Electron Catcher (EC)

SciBar

ν

2 m 4m

50 m 100 m 440 m MiniBooNE Detector

Decay region

SciBooNE Detector Target/Horn

Phys.Rev.D78,112004(2008)

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Birmingham HEP Seminar

MiniBooNE Collaboration

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MiniBooNE detector

Located 540 m from target
Mineral oil Cherenkov detector
n = 1.47
Select ν̅µ with single muon and decay

electron signal.

Total mass: 800 ton
Main component: CH2
Taking beam data since 2002

ank

Signal Region Veto Region

50 m 100 m 440 m MiniBooNE Detector

Decay region

SciBooNE Detector Target/Horn

2 detectors share the beam and the target material (both carbon)

Nucl.Instrum.Meth.A599:28-46,2009

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Data sets

Protons on target (x1E20) 1 2

Delivered For analysis

Date

Jun Jul Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug '07 '08

ν ν ν

Period BNB Mode SciBooNE POT MiniBooNE POT

Sep. 2002 - Dec. 2005

Neutrino – 5.58 × 1020

Jan. 2006 - Aug. 2007

Antineutrino 0.52 × 1020 (from Jun. 2007) 1.71 × 1020

Oct. 2007 - Apr. 2008

Neutrino 0.99 × 1020 0.83 × 1020

Apr. 2008 - present

Antineutrino 1.01 × 1020 (until Aug. 2008)

ngoing

Analysis of the full antineutrino data sets presented today

SciBooNE: (0.5 + 1.0) x 1020 POT
MiniBooNE: (1.7 + 8.4) x 1020 POT

MiniBooNE SciBooNE

8.4 x 1020

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Data Analysis

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Analysis Overview

SB + MB Rec. Eν Data SB + MB Rec. Eν Prediction

Oscillation Fit

Simultaneous fit to data from both detectors

Advantages: Direct fit for disappearance in SciBooNE and MiniBooNE. Accounts for oscillation in both detectors. Correlation between the two constrains systematic error.

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Thu Nov 6 17:18:43 2008

(GeV)

True E

0.5 1 1.5 2 2.5 3 Flux 1 2 3 4 5

9

10 ×

Generated in FV Total selected SciBar stopped MRD stopped MRD penetrated

(All CC event)

True E

Eν

SciBooNE event selection

Select MIP-like energetic tracks (Pµ>0.25GeV)
Reject side-escaping muons.
3 samples:
SciBar-stopped (Pµ,θµ)
MRD-stopped (Pµ,θµ)
MRD-penetrated (θµ)

νμ μ- p

CC event candidate

ν̅µ μ+ W N X

Use charged current inclusive sample

SciBar EC MRD

SciBar stopped MRD stopped MRD penetrated

μ+ μ+ μ+

Pµ: Muon momentum reconstructed by its path-length θµ: Muon angle w.r.t. beam axis

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Neutrino event selection

Booster provides pulsed beam with

1.6 µsec width.

Require the event time to be within the

2 µsec beam window.

Less than 0.5% cosmic ray

contamination.

~10 k events total.

sec) µ Event timing (

2

2 4 6 8 10 12 14 16 18 Events / 200 ns 1 10

2

10

3

10

Entries 31689

MRD matched event MRD stopped event

MRD matched/stopped event timing

Beam timing

Cosmic background

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MiniBooNE reconstruction

Employ same selection/reconstruction

as used in previous MiniBooNE-only analysis (PRL 103, 061802 (2009))

Select CC quasi-elastic (QE) (ν̅µp→µ+n)

like events by requiring hits from muon and its decay electron.

Reconstruct muon kinematics from the

Cherenkov light yield.

Reconstruct neutrino energy from

muon kinematics.

>68 k events!

e µ !µ

12C

p n

W+

CCQE !µ

µ- !µ

p n

Erec

ν

= m2

p − (mn − EB)2 − m2 µ + 2(mn − EB)Eµ

2(mn − EB − Eµ + pµ cos θµ) ,

n p ν̅µ

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Wrong Sign Backgrounds

MiniBooNE Phase II Letter of Intent Nucl.Phys.Proc.Suppl.159:79-84,2006 arXiv:1102.1964 [hep-ex]

π+ π+ π-

ν̅ mode spectrum ν mode spectrum

(rad)

0.05

0.1 0.15 0.2 0.25 Predicted Events 2000 4000 6000 8000 10000 12000 (a)

mode

(rad)
0.05

0.1 0.15 0.2 0.25 Predicted Events 200 400 600 800 1000 1200 1400 1600 1800 2000

µ

+
p+Be

µ

p+Be

(b)

mode

HARP region

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vertex resolution ~5 mm

SciBooNE WS Constraint

νµ CC-QE candidate (νµ + p → µ + n) νµ CC-QE candidate (νµ + n → µ + p)

SciBar MRD EC

ADC hits (area ∝ charge) TDC hits (32ch OR)

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MiniBooNE WS Constraints

1.CCQE muons have different angular distributions

Excellent angular resolution due to

cosmic muon calibration 2.CCπ+ event selection:

Tag νµN→µ−π+N events with two

Michel electrons

π- captured by C, do not decay
Cannot tag νµN→µ+π−N events:
nly 1 Michel
Two Michel sample is 85% pure WS
Check with muon lifetimes

s

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WS Constraints

Entries 180

(GeV)

rec.

" E 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 5 10 15 20 25 30

Entries 180

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 5 10 15 20 25 30

Entries 180 Entries 4676

(GeV)

rec.

" E 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 100 200 300 400 500 600 700

Entries 4676

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 100 200 300 400 500 600 700

Entries 4676

Eν (GeV) ~90% ν̅ purity

P r e l i m i n a r y

Eν (GeV)

2-track QE-like sample 1-track w/o activity sample

~90% ν purity

ν (wrong sign)

(GeV)

True E

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 neutrino flux scale 0.2 0.4 0.6 0.8 1

+

CC1

CCQE ALL

SciBooNE & MiniBooNE WS constraints adjust prediction by ~20% and reduce errors to ~15%

µ

cos
1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1 Events 10

2

10

3

10

4

10

MC

MC
= 1)
= 1,
(

MC

T data

Composition

Predicted

: 29 %

µ

: 71 %

µ

Phys.Rev.D 84 072005 (2011)

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Oscillations at both detectors

Oscillation reaches maximum

at the first oscillation peak,

then washes out at high Δm2

by integrating over neutrino energy.

Since we compare the MB flux

with SB, P(MB)/P(SB) is the expected signal.

Ratio can go up or down

depending on Δm2.

]

2

[eV

2

m ∆

1

10 1 10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

P(SB) P(MB)

]

2

[eV

2

m ∆

1

10 1 10 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

P(MB)/P(SB)

Oscillation maximum at SB Oscillation maximum at MB Sensitive region ν̅µ survival prob. for the total # of events sin22θ = 1

48 Wednesday, 16 January 13

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SciBooNE event predictions

Fit in bins of

reconstructed neutrino energy

Need to understand

contributions from

Targets, C and H
Process, QE, 1pi, npi

(GeV)

QE

E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 events per bin 100 200 300 400 500 600 (GeV)

QE

E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 events per bin 50 100 150 200 250 300 350

RS WS C H C H

Erec

ν

= m2

p − (mn − EB)2 − m2 µ + 2(mn − EB)Eµ

2(mn − EB − Eµ + pµ cos θµ) ,

49 Wednesday, 16 January 13

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(GeV)

QE

E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 events per bin 100 200 300 400 500 600 (GeV)

QE

E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 events per bin 50 100 150 200 250 300 350

SciBooNE event predictions

Fit in bins of

reconstructed neutrino energy

Need to understand

contributions from

Targets, C and H
Process, QE, 1pi, npi

RS WS QE 1pi npi QE 1pi npi

Erec

ν

= m2

p − (mn − EB)2 − m2 µ + 2(mn − EB)Eµ

2(mn − EB − Eµ + pµ cos θµ) ,

50 Wednesday, 16 January 13

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar (GeV)

QE

E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

events per bin

500 1000 1500 2000 2500 3000 3500 4000 4500

(GeV)

QE

E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

events per bin

200 400 600 800 1000

MiniBooNE event predictions

Fit in bins of

reconstructed neutrino energy

Need to understand

contributions from

Targets, C and H
Process, QE, 1pi, npi

RS WS C H C H

Erec

ν

= m2

p − (mn − EB)2 − m2 µ + 2(mn − EB)Eµ

2(mn − EB − Eµ + pµ cos θµ) ,

51 Wednesday, 16 January 13

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Imperial College London Morgan O. Wascko

Birmingham HEP Seminar (GeV)

QE

E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

events per bin

500 1000 1500 2000 2500 3000 3500 4000 4500

(GeV)

QE

E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

events per bin

200 400 600 800 1000

MiniBooNE event predictions

Fit in bins of

reconstructed neutrino energy

Need to understand

contributions from

Targets, C and H
Process, QE, 1pi, npi

RS WS QE 1pi npi QE 1pi npi

Erec

ν

= m2

p − (mn − EB)2 − m2 µ + 2(mn − EB)Eµ

2(mn − EB − Eµ + pµ cos θµ) ,

52 Wednesday, 16 January 13

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Birmingham HEP Seminar

(GeV)

Reconstructed E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.05 0.1 0.15 0.2 0.25

Total err. Flux err. MiniBooNE det. err.

Fractional uncertainties

- Total error
- MB detector error
- Flux error

Systematic uncertainties(1)

Use HARP p-Be interaction measurement

uncertainty for the error analysis.

Becomes negligible after taking ratio between

SciBooNE and MiniBooNE

Flux uncertainties

- Cross section used

for MC production

- HARP data
- Spline interpolation
f HARP data

1 2 3 4 5 6 7 50 100 150 200

< 0.06

!

" 0.03 <

hppi_profile_0

1 2 3 4 5 6 7 50 100 150 200

< 0.09

!

" 0.06 <

hppi_profile_1

π+ production cross section pπ (GeV) pπ (GeV)

8 GeV Proton π νμ μ Be

53 Wednesday, 16 January 13

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Reconstructed E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.05 0.1 0.15 0.2 0.25

Total err. Xsec err. MiniBooNE det. err.

Fractional uncertainties

Systematic uncertainties (2)

Variations of Q2 (muon angle)

distribution can change relative acceptance.

SciBooNE: (mostly) forward muons
MiniBooNE: isotropic acceptance.
The major source of the systematic

error, together with the MB detector response error.

in- f l. f

)

2

(GeV

2

Q

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Events

2000 4000 6000 8000 10000 12000 14000 1 1.01 1.02 1.03 1.04 1.05 1.1 1.2 1.3 1.4 1.5

!

(GeV)

A

M

Cross section uncertainties

MiniBooNE CCQE sample Q2 distribution

- Total error
- MB detector error
- Cross section error

54 Wednesday, 16 January 13

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Oscillation fit

The χ2 ranges over bins

in reconstructed energy for both SciBooNE and MiniBooNE.

Use Δχ2 test statistic

and Feldman-Cousins method for analysis

Construct one large

error matrix for both detectors simultaneous

Strong correlations

between detectors constrain errors powerfully

MB SB MB-SB MB-SB

55 Wednesday, 16 January 13

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Results

56 Wednesday, 16 January 13

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Uncertainty reduction

(GeV)

QE

E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

ratio: data/MC

0.8 1 1.2 1.4 1.6

(GeV)

QE

E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

ratio: data/MC

0.6 0.8 1 1.2 1.4 1.6 1.8 2

(GeV)

QE

E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

double ratio: MB/SB (data/MC)

0.6 0.8 1 1.2 1.4 1.6

MiniBooNE SciBooNE Data/MC ratios with errors show reduction of systematic uncertainties Both SciBooNE and MiniBooNE show slight data excesses

57 Wednesday, 16 January 13

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90% CL limit

No disappearance signal
bserved
Data consistent with null
scillation hypothesis.
The observed limit shows

slight deviations from the ±1σ band.

World’s strongest limit at

0.2 < Δm2 < 60 eV2

)

(2

2

sin

0.2 0.4 0.6 0.8 1

)

2

(eV

2

m

2

10

1

10 1 10

2

10

Phys. Rev. D 86, 052009 (2012).

58 Wednesday, 16 January 13

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Discussion

Possible Improvements:
Dominant uncertainties:

neutrino x-section and MiniBooNE detector response.

To reduce detector

error, need identical detectors or 10~2MeV e− calibration.

Further analysis of

SciBooNE (and MiniBooNE) data could reduce the cross section errors if we had newer/better cross section models.

(GeV)

Reconstructed E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.05 0.1 0.15 0.2 0.25

Total err. Xsec err. MiniBooNE det. err.

Fractional uncertainties

Size of errors at MB

59 Wednesday, 16 January 13

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(GeV)

QE,RFG

E
1

10 1 10 )

2

(cm

2

4 6 8 10 12 14 16

39

10 ×

MiniBooNE data with total error =1.000

=1.03 GeV,

eff A

RFG model with M =1.007

=1.35 GeV,

eff A

RFG model with M =1.03 GeV

A

Free nucleon with M

NOMAD data with total error SciBooNE data with preliminary error

(b)

Growing Consensus

We need broad coverage of

neutrino interactions

➡Model independent

measurements at many energies, nuclei

Move away from process cross-

sections

σ(QE), σ(res π), σ(coh π)
Instead measure final state particle

cross-sections

σ(CC), σ(µ), σ(µ+p), σ(µ+π)

➡Since θ13 is large, we need to

understand these systematics in

rder to measure CP violation!

pµ cosθµ

T2K

pµ cosθµ

Argoneut

pµ cosθµ

MINERvA

T. Katori (MIT)

60 Wednesday, 16 January 13

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Conclusions

We have performed a joint search for muon antineutrino

disappearance at Δm2 ~ 1eV2 with SciBooNE and MiniBooNE.

No evidence for numubar disappearance.
Set world’s best 90%CL limit at 0.2 < Δm2 < 60 eV2.
Pushed limits into interesting regions for global fits.
(Still waiting for new global fits...)
Phys. Rev. D 86, 052009 (2012).

61 Wednesday, 16 January 13

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Thanks!

62 Wednesday, 16 January 13

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Birmingham HEP Seminar Cl 95% Ga 95%

νµ↔ντ νe↔νX

100 10–3 ∆m2 [eV2] 10–12 10–9 10–6 102 100 10–2 10–4 tan2θ

KARMEN2

νe↔ντ νe↔νµ

CDHSW

KamLAND 95% SNO 95% Super-K 95%

all solar 95% http://hitoshi.berkeley.edu/neutrino All limits are at 90%CL unless otherwise noted CHOOZ Bugey CHORUS NOMAD CHORUS N O M A D NOMAD K 2 K

SuperK 90/99% LSND 90/99%

MiniBooNE MINOS

Oscillation Observations

Atmospheric region:

Δm2 ~ 10-3 eV2

Super-K, K2K, MINOS, etc
Solar region:

Δm2 ~ 10-5 eV2

SNO, Super-K, KamLAND, etc

Only 2 Δm2 regions are allowed in the current SM with 3 neutrino generations

However, there is one more region claimed by the LSND experiment at Δm2 ~ 1 eV2

63 Wednesday, 16 January 13

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What does MiniBooNE claim?

1. No νe excess in νµ beam above 475 MeV.

➡ Maximal oscillation sensitivity if LSND is L/E and CPT invariant.

2. 3σ excess (128 ± 43) of νe candidates in νµ beam below 475

MeV.

➡ Does not fit well to a 2ν mixing hypothesis

3. Small excess (18±14) below 475 MeV inνµ beam.

➡ Rules out some νµ beam low-E excess explanations.

4. Small excess (20.9 ± 14) inνµ beam above 475 MeV.

➡ Null hypothesis in 475-1250 MeV region has p-value 0.005 ➡ 2ν fit prefers LSND-like signal at 99.4% CL.

64 Wednesday, 16 January 13

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Comparing MB to LSND

Fit to 2ν mixing model Model-independent plot of inferred

scillation probability

Phys.Rev.Lett.105:181801,2010

65 Wednesday, 16 January 13

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νµ Disappearance (cont’d)

Large allowed region from global fit to world data with (3+1)

model, if νµ and νµ fit independently.

Try to improve MiniBooNE results with a near detector

(SciBooNE).

Flux+shape analysis with reduced systematic error.
G. Karagiorgi, et al. Phys. Rev. D

80, 073001 (2009)

Allowed regions from (3+1) global fits

)

µ µ

θ (2

2

sin )

2

(eV

41 2

m ∆

4

10

3

10

2

10

1

10 1

2

10

1

10 1 10

2

10 (3+1) SBL 90% CL ν SBL 99% CL ν 90% CL

µ

ν MiniBooNE

1

)

µ µ

θ (2

2

sin )

2

(eV

41 2

m ∆

3

10

2

10

1

10 1

2

10

1

10 1 10

2

10 (3+1) SBL 90% CL ν SBL 99% CL ν 90% CL

µ

ν MiniBooNE

νµ disappearance νµ disappearance

(3+1) (3+1)

MiniBooNE limits

66 Wednesday, 16 January 13

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MiniBooNE prediction

(GeV)

Reconstructed E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Total err. Flux + X-sec. err. MiniBooNE det. err. Fractional uncertainties

Fractional error

MiniBooNE-only Flux/X-sec and total error Flux/X-sec and total error constrained by SciBooNE data MiniBooNE detector response error

Successfully reduced flux and cross section errors to the same level as the MiniBooNE detector response errors.

67 Wednesday, 16 January 13

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Simultaneous Fit

Fit reconstructed Eν distributions from SciBar-stopped, MRD-

stopped and MiniBooNE samples simultaneously.

16 bins/sample x 3 sample = 48 bins
All bin-to-bin correlation is included into the fit.
Off-diagonal elements are strongly correlated.
Fake Data

■ MC with error (Diagonal part)

* MiniBooNE distribution is

scaled by ~1/7

5 10 15 20 25 30 35 40 45 500 1000 1500 2000 2500 3000 3500 4000 4500

SciBooNE SciBar-Stop SciBooNE MRD-Stop MiniBooNE

0.3 1.9 0.3 1.9 0.3 1.9 GeV Eν(GeV) Eν(GeV) Eν(GeV)

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Simultaneous Fit

MC prediction is renormalised by the

number of events in SciBooNE.

Evaluate Δχ2 =

χ2(each point) -χ2(best)

Again, Feldman-Cousins’s method is

used to determine the CLs.

0.86 0.88 0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 0.5 1 1.5 (GeV) reconstructed Eν (GeV) Δm2=9eV2 1.04 0.86 0.88 0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 0.5 1 1.5 Δm2=1eV2

sin22θ = 0.1

- SciBooNE SciBar-stoped
- SciBooNE MRD-stopped
- MiniBooNE

Survival probability

χ2 =

BINS

i,j

(di − Npi)Mij−1(dj − Npj) (

di: Data pi: Prediction (function of osc. parameter) Mij: 48x48 covariance matrix N: Renormalization factor

69 Wednesday, 16 January 13

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Predicting oscillation signal

Mean ν path-length for SciBooNE events: ~76m
Mean ν path-length for MiniBooNE events: ~520m
Each has 50m spread due to the finite length of the

decay volume

We consider three effects:
Oscillation at SciBooNE
Oscillation at MiniBooNE
Smearing effect due to 50m spread

Travel distance (m) 20 40 60 80 100 120 140 0.05 0.1 0.15 0.2 0.25 0.3

9

10 × Travel distance (m) 460 480 500 520 540 560 580 600 1000 2000 3000 4000 5000

50 m 100 m 440 m MiniBooNE Detector

Decay region

SciBooNE Detector Target/Horn

SciBooNE ν path-length 50m 50m Mean: 76m MiniBooNE ν path-length Mean: 520m

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Simultaneous fit sensitivity

Sensitivities of the two

analysis method are (roughly) the same.

Simultaneous fit sensitivity

curve is smoother because

f smaller binning effects

than the spectrum fit analysis.

2

2

sin 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 ]

2

[eV

2

m

1

10 1 10

CDHS 90% CL limit CCFR 90% CL limit MiniBooNE only 90% CL limit SB + MB 90% CL expected (Simu. fit) (Simu. fit)

1

± SB + MB90% CL SB + MB 90% CL expected (Spec. fit)

71 Wednesday, 16 January 13

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Simultaneous fit result

Events 5000 10000 15000 20000 25000 30000 Data Null oscillation Non-CCQE events

(GeV)

Reconstructed E

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 Ratio 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 Best fit = 0.5

2

2

, sin

2

= 1.0 eV

2

m

= 0.5
2

2

, sin

2

= 10.0 eV

2

m

Events

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

(GeV)

Reconstructed E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 Ratio 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

Data Null oscillation Non-CCQE events

(GeV)

Reconstructed E

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

Best fit = 0.5

2

2

, sin

2

= 1.0 eV

2

m

= 0.5
2

2

, sin

2

= 10.0 eV

2

m

SciBooNE

MiniBooNE SciBar-stop MRD-stop

χ2(null) = 45.1/48(DOF) χ2(best) = 39.5/46(DOF) Δχ2 = χ2(null) - χ2(best) = 5.6 Δχ2 (90%CL, null) = 9.3 (estimated by simulation)

No significant oscillation signal observed.

Best: Δm2 = 43.7 eV2, sin22θ = 0.60

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2

2

sin 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 ]

2

[eV

2

m

1

10 1 10

CDHS 90% CL limit CCFR 90% CL limit MiniBooNE only 90% CL limit SB + MB 90% CL expected (Simu. fit) (Simu. fit)

1

± SB + MB 90% CL SB + MB 90% CL observed (Simu. fit)

90% CL limit from simultaneous fit

The observed limits

are within the ±1σ band.

Another support for

null oscillation signal.

World strongest limit at

10 < Δm2 < 30 eV2

Constrain sterile

neutrino mixing parameters.

Sensitivity Observed

73 Wednesday, 16 January 13

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systematic uncertainties

TABLE VIII. List of systematic uncertainties considered. Category Error Source Variation Description π+/π− production from p-Be interaction Spline fit to HARP data [19]

Sec. II B

K+/K0 production from p-Be interaction Tables VIII and IX in Ref. [21]

Sec. II B

(i) Nucleon and pion interaction in Be/Al Table XIII in Ref. [21]

Sec. II B

Flux Horn current ±1 kA

Sec. II B

Horn skin effect Horn skin depth, ±1.4 mm

Sec. II B

Number of POT ±2%

Sec. II B

Fermi surface momentum of carbon nucleus ±30 MeV

Sec. III B 1

Binding energy of carbon nucleus ±9 MeV

Sec. III B 1

(ii) CC-QE MA ±0.22 GeV

Sec. III B 1

Neutrino CC-QE κ ±0.022

Sec. III B 1

interaction CC-1π MA ±0.28 GeV

Sec. III B 2

CC-1π Q2 shape Estimated from SciBooNE data

Sec. III B 2

CC-coherent-π MA ±0.28 GeV

Sec. III B 3

CC-multi-π MA ±0.52 GeV

Sec. III B 4

∆ re-interaction in nucleus ±100 %

Sec. III B 2

(iii) Pion charge exchange in nucleus ±20 %

Sec. III B 5

Intra-nuclear Pion absorption in nucleus ±35 %

Sec. III B 5

interaction Proton re-scattering in nucleus ±10 %

Sec. III B 5

NC/CC ratio ±20 %

Sec. III B 5

PMT 1 p.e. resolution ±0.20

Sec. II D

Birk’s constant ±0.0023 cm/MeV

Sec. II D

(iv) PMT cross-talk ±0.004

Sec. II D

Detector Pion interaction cross section in the detector material ±10 %

Sec. II D

response dE/dx uncertainty ±3%(SciBar,MRD), ±10%(EC)

Sec. II D

Density of SciBar ±1 %

Sec. II C

Normalization of interaction rate at the EC/MRD ±20 %

Sec. III A

Normalization of interaction rate at the surrounding materials ±20 %

Sec. III A

74 Wednesday, 16 January 13

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SOLiD

solid segmented plastic scintillator detectors

Novel approach to detect antineutrinos

at reactors

composite scintillator cells with Li6
compact system with minimal shielding

(1.5m footprint for 1T Fiducial mass)

very low sensitivity to gamma

background

can achieve better signal to

background ratio than traditional liquid scintillator system

Originally developed for reactor

monitoring purposes

~7-9m Δm2=2.35, sin22θee = 0.165

To test reactor flux and Ga anomalies Antonin Vacheret <Antonin.Vacheret@physics.ox.ac.uk>

75 Wednesday, 16 January 13

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To test reactor flux and Ga anomalies Antonin Vacheret <Antonin.Vacheret@physics.ox.ac.uk>

SOLiD

solid segmented plastic scintillator detectors

Measurement at ILL (2 years)

(~50k events)

Baselines assumed: 7.5 m near

and 9 m far (being optimised)

(ILL 0.8m x 0.4m core can

provide best resolution on SBL

scillations)
shape analysis using two detector

baseline

signal from ratio of spectra
3D vertex reconstruction (< 10

cm resolution)

σE/E ~ 0.1 MeV

76 Wednesday, 16 January 13

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DAEδALUS

arXiv:1006.0260 [physics.ins-det] 20km 8km 1.5km

sc max (π/2)

at 40 MeV

ff max (π/4)

at 40 MeV

νµ→νe

νe e+ p n H2O w/ Gd π+→νµ µ+ →e+νµνe

Constrains flux

High power cyclotrons create massiveνµ flux at multiple baselines LBNE

nly

LBNE & DAEdALUS

DAEdALUS Physics studies done assuming H2O detector in LBNE, but same performance achievable with Hyper-K or LBNO

77 Wednesday, 16 January 13

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7Li (99.99%)

sleeve

9Be target

surrounded by D2O

Proton beam

Medium term: IsoDAR

0.01 0.1 1 10 100 0.001 0.01 0.1 1

sin22!new "m2 (eV2)

95% CL

IsoDAR PBq source KATRIN Reactor/ SAGE/GALLEX Global fit μDAR

(3+2) with Kopp/Maltoni/Schwetz Parameters 0.85 0.90 0.95 1.00 1 2 3 4 5 6 7 L/E (m/MeV) Observed/Predicted (3+1) Model with !m2 = 1.0 eV2 and sin22"=0.1 0.85 0.90 0.95 1.00 1 2 3 4 5 6 7 L/E (m/MeV) Observed/Predicted

arXiv:1205.4419 [hep-ex] Adriana Bungau <A.Bungau@hud.ac.uk> To test reactor flux and Ga anomalies DAEδALUS

High power cyclotrons create

highνe flux

n+Li7→Li8
➥νe , <Eν>=6.4MeV
Placed near a goodνe detector

(e.g. KamLAND) gives excellent sensitivity to sterile oscillation

UK involved in accelerator and

beam dump studies

78 Wednesday, 16 January 13

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NuSTORM

arXiv:1206.0294 [hep-ex] νSTORM Must reject the wrong sign µ with high efficiency Multiple sterile ν channels Appearance Channel:

νe →νµ

150 m ~ 1500 m To test LSND & MiniBooNE, Ga, and reactor anomalies

νe νµ

Event rates/100T at Fe ND 50m from straight with µ+ stored

Received positive feedback from Fermilab PAC http://www.fnal.gov/directorate/program_planning/ phys_adv_com/PAC%20Comments%20and %20Recommendations.pdf http://www.fnal.gov/directorate/program_planning/June2012Public/P-1028_LOI_Final.pdf

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NuSTORM: oscillations

νSTORM νe → νµ appearance

(CPT invariant channel to MiniBooNEνe)

arXiv:1205.6338 [hep-ex] Christopher Tunnell <c.tunnell1@physics.ox.ac.uk> 3+1 Assumption χ2 stats

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NuSTORM physics programme

As an experiment, NuSTORM can:

✓ Perform direct tests of the LSND and MiniBooNE anomalies. ✓ Perform direct tests of the Gallium and reactor anomalies. ✓ Test the CP- and T-conjugated channels, constrain with

disappearance.

✓ Make precise and unique measurements of νµ and νe cross-

sections

As a facility, NuSTORM:

✓ Provides an accelerator technology test bed ✓ Provides a powerful ν detector test facility

As a programme, NuSTORM:

✓ Provides an important step on the path toward discovery in

neutrinos and collider physics νSTORM Excellent synergy with superbeams! Valuable physics input for δCP searches

81 Wednesday, 16 January 13

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NuSTORM ν Cross-sections

NuSTORM presents only way to measure νe,νµ

(&νe,νµ ) cross-sections in the same detector(s)

Supports future long-baseline experiments!
Eν matched well to needs of these experiments

νSTORM arXiv:1206.6745 [hep-ph] Recent calculations showing expectations for differences between

νe and νµ cross-sections We need data!

NuSTORM members have submitted a statement to the PPAP and the CERN Strategy Committee

82 Wednesday, 16 January 13