Tokai Super Kamiokande R OBERT J. W ILSON FOR THE - - PowerPoint PPT Presentation

ROBERT J. WILSON

FOR THE T2K COLLABORATION

15 DECEMBER 2010 NNN2010 – TOYAMA, JAPAN

ν ν ν ν ν ν ν ν

Tokai Super‐Kamiokande

T2K Goals

4 R.J.Wilson/Colorado State University

Measure last unknown mixing angle θ13 using νμ ➞ νe

appearance

Precise measurement of the atmospheric parameters θ23 and

Δm322 using νμ ➞ νμ disappearance

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 E(GeV)

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Approximation to 3‐flavor vacuum mixing with Δm21

2 << Δm32 2

Effectively 2‐flavor mixing Amplitude proportional to sin22θ13 No evident CP phase δ dependence L/E chosen for oscillation maxima

T2K L = 295 km ⇒ Eν

Pmax ≈ 0.6 GeV

νe Appearance in a νμ Beam

sin2θ23=0.5 sin22θ13=0.15

0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0.00

Neutrino Cross Sections

Charged‐Current Quasi‐Elastic (CCQE) dominant near 1st oscillation max Good efficiency and energy resolution in Super‐K Major Backgrounds at Super‐K νμ disappearance: CC π+ is comparable size to CCQE in νμ measurement νe appearance: NC π0, since γ and e indistinguishable in Super‐K These factors guided the beam and near detector design

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Neutrino Beam Flux

On‐axis beam spectrum peaks ~2 GeV Want to maximize neutrino flux at the appearance probability peak Narrow spectrum to reduce backgrounds from higher energy processes

ν flux – 30 GeV p MR ON‐AXIS

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π μ

θ

νμ

) cos ( 2

2 2

θ

π π μ π ν

p E m m E − − =

Correlation between neutrino energy and direction with pion energy

ν flux – 30 GeV p MR

Optimum for 1st max flux and background reduction at ~2.5° off‐axis

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Off‐Axis Beam Flux

ON‐AXIS

0 m 280 m 295 km

π p

2.5º

Target Near Detector Far Detector (SK)

ν

120 m

Muon monitor Decay pipe &Horns On-axis detector Off-axis detector

μ

J-PARC

ND280

(INGRID)

T2K Schematic

Beam monitoring Primary beam monitors (intensity, position, profile) Muon monitor after the decay pipe On‐axis detector (INGRID) at 280 m from the target Beam characterization and cross section measurements Near Detector at 280 m (ND280) 2.5° off‐axis from the beam Far detector neutrino flavor and flux measurement Super‐K 2.5° off‐axis from the beam

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Unoscillated flux at Super‐K

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MC

Almost pure νμ beam νe contamination ~1%

~0.5% νe contamination at the peak

Oscillation Physics Sensitivity

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δCP Dependence

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• J. Boehm

3‐flavor mixing in vacuum (matter effect is small for T2K baseline)

Effect of CP on the phase term is δ→−δ hence the nomenclature δCP Oscillation measurement, and measurement of sin22θ13, depends on δCP If any angle is zero oscillation measurement is not sensitive to δCP

⇒ measurement of θ13 is critical for future CPV experiments

T2K θ13sensitivity (normal hierarchy)

sin2 θ12 = 0.8704 Δm2

12 = 7.6 x 10‐5 eV2

sin2 θ23 = 1.0

Exposure: 750 kW X 5 X 107s X 22.5 kt fid. mass

sin2θ13 sensitivity depends on unknown δCP ; usually given for δCP =0

MINOS – Nu2010

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Δm2

23 = 2.4 x 10‐3 eV2

Systematics: νμ → νe

Expected backgrounds at Super‐K

Intrinsic νe in beam, ~60% False e‐ candidates, e.g. from NC π0, ~40%

⇒ important to understand systematics on these backgrounds

Analysis goal is to keep fractional uncertainty on each

background source to < 10%

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νμ → νe appearance sensitivity

Sensitivity goal : 0.006 (0.008) for normal (inverted) hierarchy

(~1/20 CHOOZ limit)

δCP= 0, Δm223 = 2.5 x 10‐3 eV2 Effect of systematics

Design Goal: 3.75 MW × 107s

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Nν

• bs

sin22θ = 1.0 Δm2 = 2.7 x 10–3 eV2

sin22θ23 Δm32

2 16

Measured by Super-K

( )

ν ν ν ν μ

θ ν ν E L m E N N P

x

4 / sin 2 sin ) ( / ) (

2 32 2 23 2 null

• bs

Δ ≈ = →

νμ disappearance

R x Φν

ND

x σν

water

( )

Far/Near

Extrapolated from MC verified by NA61

Near detector flux Measured by near detectors

Systematics: νμ → νμ

Estimated Systematics uncertainties

Normalization – 10% Non‐QE/QE ratio – 20% Energy scale – 4% Spectrum width – 10%

δ(sin22θ23) δ(Δm2 23) 17 R.J.Wilson/Colorado State University

90% c .l. T 2K w/ 3.75 MW×10 7 s

MI NOS & Supe r-K pre limina ry @ Nu10

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Atmospheric parameters summary

Narrow beam spectrum

centered on oscillation maximum ⇒ good sensitivity to atmospheric parameters

Expected sensitivity Δsin22θ23≈0.01 Δm2

23 < 1.0 x 10‐4 eV2

MINOS

T2K Beam & Near Detectors

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The JPARC Facility

Nakadaira‐san talk for more details

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3 GeV RCS 30 GeV Proton Synchrotron 181 MeV Linac Neutrino Beamline ND280

(6 bunch Jan‐June 2010)

~

Accumulated Protons

First T2K run (January to June 2010) ~50 kW stable operation; 3.23 ×1019 protons for analysis Second run started Nov. 16 – rapid ramp up to current 115 kW

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Summer Shutdown 6→8 bunches

• Rep. 3.6 →3.2 sec

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Neutrino Monitor

Barrel ECAL installation finished Oct 2010 Completes ND280! On‐Axis Monitor (INGRID) Off‐Axis Detector Near Detector at 280 m ND280

Side Muon Range Detector

INGRID On‐axis monitor

First e ve nt

Beam Profile X Beam Profile Center X

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Monitor beam direction, intensity and

mean energy

Off‐axis angle measurement accuracy goal 1

mrad (< 15 MeV on off‐axis peak energy)

Beam position resolution ~ 7 cm ⇒ ~3 mm

shift at proton target

~ 10k ν interactions per day at full power

Six bunch beam structure

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ND280 off‐axis neutrino events

Event Rates (P0D+FGD)/1021 PoT : 600k μ‐ only 300k μ‐p 40k μ‐π0 8k e‐ only 5k e‐p 0.8k e‐π0

Contained vertices reconstructed in P0D and FGD Lines show (approximate) iso‐contours of off‐axis angle Outer corner is roughly 20% further off‐axis than inner corner

P0D

Off‐axis Detector Interaction Vertices

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Far Detector : Super Kamiokande IV

More details in Roger Wendell’s Talk 50 kt (22.5 kt fid.) Water Cherenkov detector: 11,129 20” PMTS in inner

detector (ID) and 1885 8” PMTS in outer detector (OD)

T2K

Dead‐timeless read out electronics and DAQ upgrade in 2008 GPS system used to select time arrival of beam events

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Unbiased event selection

Timing coincident w/ beam time (+TOF) Fully contained (No OD activity) Vertex in fiducial volume (vertex > 2 m from wall) Evis > 100 MeV no of rings =1 e‐like ring No decay electron

• Inv. mass w/ forced‐found 2nd ring

< 105 MeV Eν

rec < 1250 MeV

Evis > 30 MeV no of rings =1 μ‐like ring νμ disappearance analysis νe appearance search

SK event selection decided before the run Possible because SK is a mature & well understood detector

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T2K Events in Super‐K

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pμ = 1061 MeV/c 1 decay‐electron pμ = 1438 MeV/c 2 decay‐electrons

Jan‐June 2010 # of events Fully‐Contained (FC)

33

+ fiducial volume cut + visible E > 30 MeV (FCFV)

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∆T0 = SK trig time -T2K beam trigger time

Super‐K Time Distribution

GPS works well ‐ very good time synchronization

between T2K beam and Super‐K

Change 6‐>8 bunches since Nov. evident

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Jan‐June Nov.‐Dec.

2010/2011 Run

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Started Nov. 18th ~50% increase in data in 3 weeks Current beam power ~115 kW Aim for 150 kW × 107s by July 2011 10x 1st run data sensitivity to sin22θ13 ≈ 0.05

Design Goal: 3.75 MW × 107s July 2011 goal

Summary

1st run January–June 2010

Continuous beam at ~50 kW, accumulated 3.23 x 1019 PoT Good overall stability of beam and detector performance Measured 23 neutrino beam events (FCFV) at Super‐K Expect first results by winter 2011 conferences

Summer/fall shutdown

New kicker magnet & power supplies installed INGRID modules assembly and installation Calorimeter modules installation completed ‐ full coverage at ND280

2nd run November 2010 – Summer 2011

Aim for 150 kW x 107 s by July 2011; currently > 110 kW 90% c.l. sensitivity sin22θ13 ~ 0.05

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Supplementary

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Similar to normal hierarchy T2K insensitive to matter effects

T2K θ13 sensitivity (inverted hierarchy)

MINOS – Nu2010

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CERN NA‐61/SHINE

Neutrino beam depends upon secondary beam geometry and hadron distribution

• ff target

NA‐61/SHINE : dedicated hadron production experiment using T2K target to reduce

uncertainties in hadron production models

Pilot run in 2007 and high statistics run in 2009 : p(30 GeV) with Carbon thin

target and T2K replica target

preliminary results from 2007 used in T2K beam MC

MC=GFLUKA

T2K sensitivity and discovery potential

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3σ measurement

Beam Power Plan

Japanese Fiscal Year (starts April 1 of CY)

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