aap 2012 meeting, honolulu jelena maricic university of hawaii october 4, 2012

SUMMARY OF 13 MEASUREMENTS AND PROSPECTS

AAP 2012 meeting, Honolulu

Jelena MaricicUniversity of HawaiiOctober 4, 2012

Executive Summary

13

Summary of 13 measurementsfrom reactors 2011-2012 Daya Bay 13 ~8.7 (~8 zero exclusion)

RENO

13 ~9.8 (~6 zero exclusion)

Double Chooz


Summary of 13 measurements from beams MINOS T2K

2CP 23

213

213

213

213

213

for δ =0, sin (2θ )=1,

sin (2θ ) = 0.053 at best fit

0.01 < sin (2θ ) < 0.12 at 90% C.L.


0.03 < sin (2θ ) < 0

normal hierarcy:

inv

.19 at 90% C.L.

sin

erted hierarc

(2θ )

y:

= 0 excluded at 96% C.L.

13 ~7 (NH)13 ~9 (IH)

13 ~9 (NH)13 ~10 (IH)

~2 zero exclusion

~3 zero exclusion

Summary of 13 measurements

Global fit from Daya Bay, RENO, Double Chooz and T2K:

1

2

3

4

N

Fogli, Lisi, Marrone, Montanino, Palazzo, Rotunno: hep-ph/1205.5254 (2012)

Sin2 13 = 0.0241 ± 0.0025 (NH)

Sin2 13 = 0.0244 ± 0.0025 (IH)

13 = 8.9± 0.9(~10% relative uncertainty)

Prospects

13 measured to be non zero with > 7 C.L.

In the next 3 years expected to be known with 5% uncertainty

Going from the unknown to the best measured

neutrino mixing angle: 2003-2012

But there is more to this measurement…

Outline

Introduction

Review of the experiments

Results of measurement 13

Prospects

13

Material adopted from presentations from NOW2012 and ISNP 2012, from members of MINOS, T2K, Double Chooz, Daya Bay and RENO

Introduction

13

Starting point in 2003: CHOOZ

Last non-measured neutrino mixing angle!Only the upper limit

on the value of angle θ13 was set!

CHOOZ experiment constraint:

(e e disappearance exp)

@m2atm = 2.3 10-3 eV2

sin2(2θ13) < 0.15

(90% C.L)

CHOOZ experimentR = 1.01 2.8%(stat)2.7%(syst)

e x

M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374 M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374

13 < 11

13 central to fundamental questions CP-violation phase and mass

hierarchy

12 12 13 13

12 12 23 23

13 13 23 23

cos sin 0 cos 0 sin 1 0 0

sin cos 0 0 1 0 0 cos sin

0 0 1 sin 0 cos 0 sin cos

CP

CP

i

i

e

U

e

“Solar” 12 ~ 30° “Atmospheric” 23 ~ 45°

(SK + MINOS)

“Little mixing angle” 13 < 11° (circa 2011)

(CHOOZ)

Value of θ13 directly influences prospects of measuring CP violation

phase in the weak sector!

13 impacts measurements on ~few 100 m scale and aboveInteresting for nuclear reactor monitoring with neutrinos

Δm221=(7.50+0.19

-0.20)×10-5 eV2

(KamLAND)Δm2

32=(2.32+0.12-0.08)×10-3

eV2 (MINOS)

Hints on 13 from global fits in 2005/2008

Fogli, Lisi, Marrone, Palazzo, Rotunno: hep-ph/0806.2649v2 (2008)

sin2 13 = 0.9+2.3−0.9 ×

10−2

Fogli, Lisi, Marrone, Palazzo: hep-ph/0506083 (2005)

sin2 13 = 0.016 ± 0.010

13 ~ 5

13 ~ 7

Large uncertainty and low non-zero exclusion level.

Global fit from KamLAND in March 2011

KamLAND collaboration:hep-ex/1009.4771

sin2 13 = 0.020 ± 0.016

13 ~ 8

Large uncertainty and low non-zero exclusion level.

Review of 13 experiments

13

13 Measurement Strategies

Use muon neutrinos from accelerator: appearance search for electron neutrinos MINOS T2K

Use electron antineutrinos from nuclear reactor: disappearance search CHOOZ Double Chooz Daya Bay RENO

13 and Beam Experiments

MINOS

T2K

T2K uses off-axis beams to achieve:-Increased flux near oscillation max-Reduced high energy NC bkg

µ

µ

e

e

13 and Reactor Experiments

Reactor Near Detector Far Detector

MeV

m27.1sin2sin1

2312

132

E

LmP ee

Eν ~ 4 MeV

(Flux)L2

L~1.5km

< 14%

No Oscillations

Oscillated

e e

High precision measurement required: systematic error ~0.5%

13 & Beam Experiments

Appearance probability :

dependences in sin(213), sin(23), sign(m231), -CP phase in [0,2]

13 & Reactor Experiments• <E> ~ a few MeV only disappearance experiments

sin2(213) measurement independent of -CP

• P(e e) = 1 - sin2(213)sin2(m231L/4E) + O(m2

21/m231)

weak dependence in m221

• a few MeV e + short baselines negligible matter effects (O[10-4] )

sin2(213) measurement independent of sign(m213)

Results of measurement 13 with beams

13

MINOS Experiment

735 kmnm

MINOS - Main Injector Neutrino Oscillation Search

Two functionally identical detectors to reduce systematics

Near Detector• 1 km from target• 94 m underground, 225 mwe• Measures the energy spectrum and beam composition

Far Detector• 735 km from target• 700 m underground, 2070

mwe• Re-measures the neutrino

beam composition Near Detector980 tons

Far Detector5,400 tons

Steel/scintillator tracking calorimeters

• Alternate orthogonal orientation planes• Steel absorber 2.54 cm thick• Scintillator strips 4.1 cm wide, 1.0 cm

thick• 1 GeV muons penetrate 28 layers• Longitudinal sampling = 1.4 radiation

lengths• Optical WLS fiber readout to multi-

anode PMTs

Detector Technology

Multi-anode PMT

ExtrudedPS scint.4.1 x 1 cm

WLS fiber

ClearFiber cables

2.54 cm Fe

U V planes+/- 450

Magnetized• <B> = 1.3T• Muon energy from

range/curvature

• Distinguish μ+ from μ-

tracks

Neutrino Interactions in Detectors

tran

svers

e

dir

ect

ion n e-

m-

beam directioncolor scale represents energy deposition

nm Charged Current

nx Neutral Current ne Charged Current

long μ track & possible hadronic activity at vertex

short with compact EM

shower profile

short with diffuse shower

120 GeV protons

Focusing Horns 2 m

675 m15 m 30 m

91.7%

7.0%

e e 1.3%

Target

Neutrino modeHorns focus π+, K+

Decay Pipe

π-

π+

νμ

νμ

Monte Carlo

Neutrino Mode

Antineutrino Mode

120 GeV protons

Focusing Horns 2 m

675 m15 m 30 m

91.7%

7.0%

e e 1.3%

Target

Neutrino modeHorns focus π+, K+

Decay Pipe

π+

π-

νμ

νμ

Monte Carlo Monte CarloAntineutrino modeHorns focus π-, K-

39.9%

58.1%

e e 2.0%

ν ν

22 2 31

22

3 13sin ( )sin ( ) sinm L

PE

1.267 Δθ θμ e

νe Appearance Measurement

eν ν

2

2 2 3123

213sin ( )sin ( ) sin

LP

E1.267 Δm

θ θμ

sensitive to neutrino mixing angle θ13, δCP, mass ordering

if 0, eCP eP P In matter, νe CC scattering modifies oscillation probability ~30% in

MINOS

10.6×1020 POT (ν mode)

Electron Appearance in FHC and RHC Beam

3.3×1020 ( ν mode)ν mode Expected (LEM>0.7):

69.1 (background, if

θ13=0)

26.0 (signal, if

sin2(2θ13)=0.1)

Observe:

88 events

ν mode Expected (LEM>0.7):

10.5 (background , if

θ13=0)

3.1 (signal, if

sin2(2θ13)=0.1)

Observe:

12 events

Library Event Matching (LEM)

2CP 23

213

213

213

213

213

for δ =0, sin (2θ )=1,


0.01 < sin (2θ ) < 0.12 at 90% C.L.


0.03 < sin (2θ ) < 0

normal hierarcy:

inv

.19 at 90% C.L.

sin

erted hierarc

(2θ )

y:


ne Appearance:ν and Combined Contour

● Second generation long-baseline neutrino-oscillation experiment;

● High intensity almost pure nm beam from Main Ring in J-PARC is shot toward the Super-Kamiokande detector 295km away.

●

from Tokai to Kamioka

● The physics data-taking started in Jan. 2010, and stopped in March 2011 by the earthquake. Resumed almost a year later.

J-PARC in JAEA

Tokai

Tokyo

Kamioka

KEK

T2K experiment

J-PARC in JAEA

Super-KamiokandeJ-PARC

Results of measurement 13 with reactors

13

Locations

DoubleChooz Daya

BayRENO

ConfigurationsDouble Chooz

Daya Bay

300 mwe115 mwe

1 km400 m

Reactor Neutrino Detection Signature• Reactors as neutrino sources:

N s 1 6NFiss s

1 21011P s 1 Chooz: P =2x4.25 GWth N~2x1021s-1 Neutrino detection via inverse decay

Distinctive two-step signature: -prompt event Photons from e+ annihilation Ee = E- 0.8 MeV + O(Ee/mn) -delayed event Photons from n capture on dedicated nuclei (Gd) t ~ 30 s E ~ 8 MeVGadolinium

Target:Gd doped scintillator

1 g/l Gd in LS

¹ºe + p+ ! e+ + n

The Double Chooz Far DetectorOuter Veto (OV)plastic scintillator strips

Outer Steel Shielding250 t steel (15 cm)

Inner Veto (IV)90 m3 of scintillator in a steel vessel (10 mm) equipped with 78 PMTs (8 inches)

Buffer110 m3 of mineral oil in a steel vessel (3 mm) equipped with 390 PMTs (10 inches)

γ-Catcher (GC)22.3 m3 scintillator in an acrylic vessel (12 mm)

Target10.3 m3 scintillator doped with 1g/l of Gd compound in an acrylic vessel (8 mm)

~7m

Calibration Glove Box

Daya Bay

13 Measurement with DC Far

13

Interaction Cross-Section

• Recalculations of spectra introduced normalization shift; “anomaly”?

• Th.A. Mueller et al, Phys.Rev. C83(2011) 054615.

• P. Huber, Phys.Rev. C84 (2011) 024617

}2,1{

Reactors

,

2exp ,

4),(

R

Rf

Rf

Rth

R

p tEtE

tP

L

NtEN

Reference Spectra + Bugey4 “Anchor”

Normalize to Total Rate Measurement of Bugey4

}2,1{

Reactors

,

2exp ,

4),(

R

Rf

Rf

Rth

R

p tEtE

tP

L

NtEN

Reduces reactor normalization uncertainty

from 2.70% to 1.76%

Neutrino Candidate Selection

Prompt signal Evis = [0.7, 12.2] MeV

Delayed signal Evis = [6.0, 12.0] MeV

Delayed Coincidence Δt = [2, 100] µsec

Require Δt μ > 1 msec

PMT light noise rejection cuts

• PMT hits approx. homogeneous

• PMT hits approx. coincident in time

Multiplicity conditions:

• No extra events around signal

Background rejection:

• No coincident signal in OV

• Require Δt μ > 500 msec if Eμ > 600 MeV

Plus three irreducible backgrounds:

• Accidentals

• Cosmogenic 9Li

• Fast neutrons/stopping muons














Preliminary

Trigger efficiency• Threshold at 400keV (ε=50%)• ε=100% above 700keV

Minimum visible energy of ν signalPrompt

energy cut














• 41% of 9Li BG is rejected by additional muon veto (~5% live-time loss)

• 28% of fast neutron/stop μ BG is rejected by OV anticoincidence

Candidate Rate Variation

Before 9Li reduction cut, no OV anticoincidence applied

Not background-subtracted Rate consistent with expectation

Cross-check: Reconstructed Vertex Position

Events well-localized within target Note: no spatial cuts applied in candidate selection

Detector Calibration

1. PMT and electronics gain non-linearity calibration

LED light injection system

2. Correct for position dependence

Spallation neutron H captures

3. Correct for time stability Spallation neutron Gd

captures

4. Energy scale Radioactive sources deployed

into ν-target and γ-catcher

Energy Calibration

Neutron Detection EfficiencyEnergy & time window, Gd fraction, spill in/out effects• 252Cf source deployed into ν-target and γ-catcher

BackgroundsAccidentals• Prompt: radiation hit on PMT• Delayed: spallation neutron capture• Prevented by radiopurity & shielding• Measured from off-time windows: 0.261 +/- 0.002 day-1

Cosmogenic 9Li• Prompt: beta emission• Delayed: neutrons from long-lived decays• Measured from Δtμ & spatial muon coincidence: 1.25 +/- 0.54 day-1

Fast-n & Stopping muons• Prompt: proton recoil or muon track• Delayed: neutron capture or muon decay• Measured from high-energy spectrum: 0.67 +/- 0.20 day-1




Preliminary




Red: Best-fit Spectrum Grey: Tagged background eventsWhite: IBD Signal

Check Rate vs. Reactor Power

2 events observed in 0.84 days livetime with both reactors off(= 2.2 event/day)

→ Background rate consistent with estimation

(2.2 ±0.6 event/day)

Best fit to expected rate:sin22θ13 = 0.19 ± 0.06BG rate = 2.9 ± 1.1

event/day arXiv:1207.6632

Summary of Rate Uncertainties

Source Uncertainty w.r.t. signal

Statistics 1.1%

Flux 1.7%

Detector

Energy response 0.3%

1.0%

Edelay containment 0.7%

Gd fraction 0.3%

Δt cut 0.5%

Spill in/out 0.3%

Trigger efficiency <0.1%

Target H 0.3%

Background

Accidental <0.1%1.6%Fast-n + stop μ 0.5%

9Li 1.4%

Summary of CandidatesBoth Reactors

OnOne Reactor Pth < 20%

Total

Livetime [days] 139.27 88.66 227.93

IBD Candidates

6088 2161 8249

Prediction

Reactor B1 ν 2910.9 774.6 3685.5

Reactor B2 ν 3422.4 1331.7 4754.19Li 174.1 110.8 284.9

FN & SM 93.3 59.4 152.7

Accidentals 36.4 23.1 59.5

Total Prediction

6637.1 2299.7 8936.8

Data divided into two integration periods based on reactor power Allows use of changing signal/background ratio in fit

Double Chooz Prompt

Spectrum

Data w/ Stat. Error Bars

Best Fit Prediction

(w/ Syst. Errors)

Null Oscillation Prediction

Backgrounds

Rate+Shape: sin22θ13= 0.109 ± 0.030 (stat.) ± 0.025 (syst.)χ2/d.o.f. = 42.1/35

Rate-only: sin22θ13 = 0.170 ± 0.035 (stat.) ± 0.040 (syst.)Frequentist analysis: sin22θ13 = 0 excluded at 99.8% (2.9σ)Presented in arXiv:1207.6632, accepted by PRD

RENO 13 Measurement

13

Daya Bay 13 Measurement

13

Result

Summary and Prospects

13

Summary of 13 measurements from beams MINOS T2K

2CP 23

213

213

213

213

213

for δ =0, sin (2θ )=1,


0.01 < sin (2θ ) < 0.12 at 90% C.L.


0.03 < sin (2θ ) < 0

normal hierarcy:

inv

.19 at 90% C.L.

sin

erted hierarc

(2θ )

y:


13 ~7 (NH)13 ~9 (IH)

13 ~9 (NH)13 ~10 (IH)

~2 zero exclusion

~3 zero exclusion

Summary of 13 measurementsfrom reactors Daya Bay (June 2012) 13 ~8.7 (~8 zero exclusion)

RENO (June 2012)


Double Chooz


Summary of 13 measurements

Global fit from Daya Bay, RENO, Double Chooz and T2K:

1

2

3

4

N

Fogli, Lisi, Marrone, Montanino, Palazzo, Rotunno: hep-ph/1205.5254 (2012)

Sin2 13 = 0.0241 ± 0.0025 (NH)

Sin2 13 = 0.0244 ± 0.0025 (IH)

13 = 8.9± 0.9(~10% relative uncertainty)

Energy Spectra Spectral

shape contains some potentially peculiar features when compared to expectation.

Double Chooz

RENO

Daya Bay sin2(213)=0.12

m2atm= 3.0 10-3 eV2

Far/Near ratiosimulated

Summary and Prospects Better understanding of spectral shape: hint of

new physics?!?

13 measured to be non zero with > 7 C.L. and 10% uncertainty

In the next 3 years expected to be known with 5% uncertainty

Going from the unknown to the best measured neutrino mixing angle: 2003-2012!

THANK YOU!

aap 2012 meeting, honolulu jelena maricic university of hawaii october 4, 2012

Documents

exclusion slide

minos slide

measurement slide

introduction slide

executive summary slide

relative uncertainty

exclusion double chooz

reactor experiments