Status of T2K

Tokai to Kamioka Neutrino Project at J-PARCJune 21, 2004

Koichiro Nishikawa

Kyoto University

beam of ＜ 1GeVKamioka

J-PARC(Tokai-village)

→ → xx disappearance

→ → ee appearanceNC measurement

0.75 MW 50 (40) GeV PS

Super-K: 50 ktonWater Cherenkov

~Mt “Hyper Kamiokande”

4MW 50GeV PS

CP violation proton decay

Approved exp (x102 of K2K)

Future Extension

“T2K” (Tokai-to-Kamioka) neutrino experiment

LOI: hep-ex/0106019

Collaboration• Formed in May 2003• 12 countries, 52 institutions• 148 collaborators (w/o students)

Nuclear and ParticleExperimental Facility

Materials and Life ScienceExperimental Facility

Neutrinos to Super-Kamiokande

Linac(350m)

3 GeV Synchrotron(25 Hz, 1MW)

Nuclear Transmutation

J-PARC Facility

50 GeV Synchrotron(0.75 MW)

J-PARC = Japan Proton Accelerator Research Complex

SuperKamiokande@Kamioka, Japan

C Scientific American

42m

39m

Water Cherenkovdetector

1000 m underground 50,000 ton (22,500 ton fid.) 11,146 20 inch PMTs 1,885 anti-counter PMTs

Since 1996.

Accident on 2001.

Partial recovery on 2002.

(Full recovery on 2006)

• The mixing angles 12, 23, 31, ?– How small the mixing of 1st and 3rd generation?

• Does e contain ?– Symmetry of 2nd and 3rd generation?

• How close 23 to 　 3 flavor analysis– Is sterile neutrino exist?

• Fraction in disappearance of – How large is the phase ?

• CP violation in lepton?

• Prepare for un-expected

• Neutrino beam – Suited for far detector technology

• water Cherenkov

e

　 m1　m2　m3

Neutrino beam

Strategy

• High statistics by high intensity beam• Tune E at oscillation maximum• Sub-GeV beam

– Low particle multiplicity suited for Water Cherenkov– Good E resolution : dominated by 　　n　　　p

• Narrow band beam to reduce BG

0.75MW 50GeV-PS

Off-Axis beam Super-Kamiokande

Neutrino Interaction @~1 GeV & E reconstruction

CC QEcan reconstruct E　p

CC nQE Bkg. for E measurement

NC main Bkg. for electron appe

arance

+ n → + p

-

p

(E, p)

+ n → + p + ’s

p’s

-

+ n → + p +

p

(E, p)

’s

cospEm

2mEmE

N

2Nrec

E

Lm27.1sin2sinP

22

Neutrino cross section

E　reconstruction resolution

Large QE fraction for <1 GeV Knowledge of QE cross sections

Beam with small high energy tail

QE

inelastic

E~60MeV<10% meaurement

E　(reconstructed) – E　(true)

1-sin22

non-QEresolution

m2

+ 10% bin High resolution : less sensitive to systematics

Off Axis Beam

OA3°

OA0°

(ref.: BNL-E889 Proposal)

TargetHornsDecay Pipe

Super-K.

Quasi Monochromatic Beam x 2~3 intense than NBB

Statistics at SK (OAB 2 deg,1 yr,22.5 kt)

~ 4500 tot ~ 3000 CC e ~0.2% at peak

Tuned at oscillation maximum

Neutrino energy spectrum x

OA2°

GeV

Extra handle on e contamination in the beam

Off-Axis Beam

~1/500

from K

e from + K

Intrinsic background: e /　(peak)　~ 0.002

Primary physics goals

e appearance : 　

sin2213

Estimated background in Super-K Signal

(~40% eff.)Signal +

BG 　NC

e

beam e total

0.1 12.0 10.7 1.7 0.5 24.9 114.6 139.5

0.01 12.0 10.7 1.7 0.5 24.9 11.5 36.4

sin2213

m2

Off axis 2 deg, 5 years

Off axis 2 deg, 5 yearsat

sin2213>0.006 C

HO

OZ

exc

lud

ed

Precision measurement of 23 , m223

possible systematic errors and phase-1 stat.•Systematic errors

• normalization (10% （ 5%(K2K))• non-qe/qe ratio (20% (to be measured))• E scale (4% (K2K 3%))• Spectrum shape (Fluka/MARS →(Near D.))• Spectrum width (10%)

OA2.5o

(sin22)~0.01 (m2

23) <1×10-4 eV2

Neutrino facility

50 GeV 0.75 MW beam !

cm

1100o

(cf. melting point 1536o)

3.3E14 ppp w/ 5s pulse

When this beam hits an iron block,

Material heavier than iron would melt.

Thermal shock stress

(cf. stress limit ~300 MPa)

Material heavier than Ti might be destroyed.

Cooling power and radiation shield

GPaTE 3

radio activity

> 1000Sv/h

Jan.10, 2004 meeting from Director General of KEK

• In October CSTP rated the T2K project as C, the worst rating. We thought that CSTP's decision was completely wrong. So, we, KEK, struck back to get the better rating.

• Thanks to supports by many people, notably by M. Koshiba and some politicians, we were successful to have CSTP update the rating. Shocked by the rating, MEXT immediately established the review committee to judge if the T2K's should be funded next year, considering the scientific merit, urgency and collaboration's competence. The review report, which is attached here, was of course favorable and sent to CSTP. The committee chairman, Professor Kodaira, and MEXT's director general, Mr. Ishikawa, responded to CSTP members' questions.

• Finally S&T Minister Motegi agreed that the committee report was reasonable. He sent his comment to Ministry of Finance.

• After tough negotiations between MEXT and MOF backed by many and strong supports, MOF approved the T2K on December 20. （ as the first year of five-year construction project)

- Now formally approved

• However MOF approved only 6 oku-yen for proposed 8 oku-yen for FY 2004. You must work harder to be more cost effective.

• I want to urge you the following. CSTP will review the T2K and the whole J-PARC project every year.

• I suspect that the present manpower for the beam line construction is too weak and you will not be able to build it properly and timely. You should show us first of all how much you will improve the present situation. I urge the non-KEK collaborators NOT to be simple users of the beam line but to fully participate in the construction of the beam line. Otherwise I am afraid that T2K may eventually be terminated. Spokesperson should have sent this kind of statement long before.

Best regards, Yoji Totsuka (KEK DG)

• Pion/Kaon production at 40-50 GeV ！

• Muon monitors @ ~140m– spill-by-spill monitoring of beam direction/intensity

• First Front detector @280m– 0 degree definition– High stat. neutrino inter. studies

• (Second Front Detector @ ~2km for future addition)

• Far detector @ 295km– Super-Kamiokande (50kt)

1.5km

295km

0.28km

Neutrino spectra at diff. dist

dominant syst. in K2K

p

140 m0 m 280 m 2 km 295 km

Task force

• Identify the common project item and cost estimate for the contributions by next meeting from all countries to agree on (August)

• Write formal (technical) proposal by end of 2004.

decay pipe

Near detector

TargetStation

-pit280m

130m

Neutrino facility in J-PARC (JFY2004-08)

Special FeaturesSpecial Features

Superconducting Superconducting combined functioncombined function magnets magnets

Off-axis beamOff-axis beam

Funded componentsFunded components

Primary proton beam line

• Normal conducting magnets

+ INR

• Superconducting arc

+ BNL,Saclay

• Proton beam monitors

+ Canada

Target station+ Canada

Target/Horn system+ US

Decay pipe (130m Cover OA angle 2~3 deg. )

being constructed

Beam dump+ UK

muon monitors+ Canada, UK

Near neutrino detector

20m

36m

3

2

SK direction

16m

5m

FGDMRD

~14m

SK

Grid profile

beam

3m1m

1m

Concept of Near Neutrino Detector Off-axis (~2o0.20)

– and e neutrino fluxes and the spectra.

– interaction study (CC-QE, non-QE, 0, )

– Kaon Contributions

On-axis (0o)– Beam direction– Divergence– Beam stability

The detector design is just started

Schedule

• Possible upgrade in future– 4MW Super-J-PARC + Hyper-K ( 1Mt water Cherenkov)

– CP violation in lepton sector

– Proton Decay

2004 2005 2006 2007 2008

MINOS

OPERA/ICARUS 5yr (~20

SK full rebuild

JHF- construction physics run K2K

2009

Sensitivity (3) to CP Violation Phase with upgrades

Preliminary

• Bkg. 　 subtraction with 2% accuracy （ red),

• bkg(2%)+selection(2%) (black) errors

• Operation of 2 yr for 　and 6.8 yr for

≧33deg at sin2213=0.01

≧14deg for large sin2213

• Understanding of background and systematics is essential

Stat

onl

y

Summary

• The first “superbeam” long baseline neutrino exp. “T2K” approved– 5 years construction (JFY2004~JFY2008)– Start physics in 2009– Try to discover non-zero 13

– precision measurement of 23, m232.

• 1st step to the CP violation in the Lepton sector

• International collaboration formed• R&D in various components in the beam line and near d

etector• Construction started

Construction status

December, 2003

Linac Area

Linac Area

3 GeV Area

3 GeV Area

31

3-50 GeV Area

3 GeV to 50 GeV

32

50 GeV

50 GeV