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Prospects of J-PARC Neutrino Program. Changgen Yang Institute of High Energy Physics Beijing. Overview of J-PARC expect to start in 2007. approved. ~1 GeV n beam. Super-K: 22.5 kt. Hyper-K: 1000 kt. 0.77 MW 50 GeV PS. 4 MW 50 GeV PS. ( conventional n beam).

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prospects of j parc neutrino program

Prospects of J-PARC Neutrino Program

Changgen Yang

Institute of High Energy Physics

Beijing

overview of j parc expect to start in 2007
Overview of J-PARCexpect to start in 2007

approved

~1GeV n beam

Super-K: 22.5 kt

Hyper-K: 1000 kt

0.77MW 50 GeV PS

4MW 50 GeV PS

( conventional n beam)

Phase-I (0.77MW + Super-K)

Phase-II (4MW+Hyper-K) ~ Phase-I  200

j parc
J-PARC

[email protected]

(60km N.EJ. of KEK)

Construction

2001~2006

(280m from target)

(Approved in Dec.2000)

jhfnu k2k as an example
JHFnu: K2K as an example

nm

SK

p+

FD

m+

Target+Horn

200m

decay pipe

100m

~250km

FD

Pion monitor

(PIMON)

MUMON

three beams

2horns

Far Det.

Decay Pipe

q

Horns

Three Beams
  • Intense
  • Wide sensitivity in Dm2
  • BG from HE tail
  • Syst. err from spectrum extrapolation

Wide Band Beam

Narrow Band Beam

  • Less HE tail
  • Less sys err from spectrum

“counting experiment”

  • Easy to tune En

momentum selected p

Off Axis Beam

  • High int. narrow band beam
  • More HE tail than NBB
  • Hard to tune En
off axis beam

Far Det.

q

Decay Pipe

Horns

Target

Off Axis Beam
comparision of spectra
Comparision of Spectra

Peak @ 800MeV~1GeV

Sharp peak for NBB/OAB

OAB produce very intense “NBB”

WBB:5200 CC int./22.5kt/yr

NBB: 620 CC int./22.5kt/yr (2GeV/c p tune)

OAB: 2200 CC int./22.5kt/yr (2degree)

n e contamination
ne contamination

NBB (LE2p)

OAB (2degree)

m-decay

m-decay

K-decay

K-decay

0.73%

(0.15%@peak)

1.0%

(0.21%@peak)

Very small ne/nm ratio at nm spectrum peak: 1~2x10-3

slide9

Requirement of Near Detector:

  • Measure the quality of neutrino beam
  • Estimate the neutrino flux and the energy spectrum at Super-K
  • Study neutrino interactions to estimate b.g. for oscillation analysis

Measurements of the neutrino beam:

  • Direction;
  • Flux/spectrum for  and e
  • Profile
  • Stability
  • Event types(QE, single  ,NC pi0 etc…)
a tool pion monitor pimon

A tool: Pion Monitor(PIMON)

nm disappearance

F/N extrapolation (incl. HE tail)

Kaon production(p/K ratio)  HE tail

ne appearance

BG : NCp0: ne~1:1, half of p0 BG from HE tail

F/N extrapolation  HE tail

Kaon production(p/K ratio)  HE tail

 ne contamination

Neutrino int. study at 280m

Precise spectrum information

physics goal of jhfnu phase i

Physics Goal of JHFnu(Phase I)

L=295km, En=0.5~2GeV(Match the WCD)

Precise determination of neutrino oscillation parameters:

sin22231%

m2321×10-4eV2

at (sin22q=1.0, Dm2=3.2×10-3eV2)

sin2213< 1%

Physics Goal of JHFnu(Phase II)

CP violation measurement

Proton decay

neutrino energy reconstruction

nl + n → l + p

l-

(El , pl)

ql

n

p

Neutrino Energy Reconstruction

Assume CC quasi elastic (CCQE) reaction

neutrino energy reconstruction1
Neutrino Energy Reconstruction

Quasi-elastic

s=80MeV

En(reconstruct)

En (True)

En(reconstruct) – En (True) (MeV)

QE dominate at ~1GeV

d m 23 2 and q 23 measurement
Dm232 andq23 measurement

P(nm→nm)=1 - cos4q13sin22q23sin2(1.27 Dm232 L/E)

~1

P(nm→ nm)

sin22q

Dm2

En (GeV)

n m disappearance
nm disappearance

1ring FC m-like

Ratio after BG subtraction

(linear)

Dm2=3×10-3 sin22q=1.0

Oscillation with

Dm2=3×10-3

sin22q=1.0

Non-QE

(log)

No oscillation

~3%

Reconstructed En (MeV)

Fit with 1-sin22q・sin2(1.27Dm2L/E)

q 13 measurement
q13 measurement
  • A mixing angle between 1st and 3rd generation , q13may be not very small
  • A discovery of nm→ne can open the new window to study CP violation in this mode
  • May be a source of baryogenesis in the universe

P(nm→ne)=sin22q13sin2q23sin2(1.27 Dm232 L/E)

n e appearance
ne appearance

Background rejection against NC p0 is improved.

sin22qme=0.05 (sin22qme 0.5sin22q13)

Dm2

CHOOZ

×20 improvement

3

5

×10-3

sin22qme

non standard n oscillation
Non standard n oscillation
  • A sterile neutrino (LSND result? 3 or 4 n’s)

with nmnm /ne measure: nmnt (/ ns)

  • non standard CP violation of nm→nt .
  • Any other unexpected phenomena
n m n t confirmation

OAB

nmnt

#p0 + #e-like

D=390±44

nmns

3.510-3

Dm232

nm →nt confirmation
  • NC p0 interaction (n + N → n + N + p0)
    • nmne CC + NC(~0.5CC) ~0 (sin22qme~0)

nm CC + NC(~0.5CC) ~0 (maximum oscillation)nt NC

#p0 is sensitive

to nt flux.

n detector
ndetector

Phase-II: Hyper-K

1,000 kt

  • Far n detectors

Phase-I: Suker-K

22.5kt (50kt)

search for n m n e
Search for nmne

sin22qme sensitivity

310-3

Phase-II

Phase-I

~310-4

102

Exposure/(22.5kt1021pot)

p0 background has to be understood with 2% level.

(n physics at a front detector)

cp violation in n oscillation
CP violation in n oscillation

L=295km : small MSW En~1 GeV : large CP asym.

  • If LSND is true, CP violation may be much larger than expect.
cp violation study
CP Violation Study

Dm122=5×10-5eV2 ,

Dm232=3×10-3eV2

sin22q13 = 0.01

q23 = p/4, q12 = p/8

  • Compare nmne withnmne

N(e+)

NO CP violation

w/o matter effect.

|d|>20 (3s discovery)

3s discovery

90% C.L.

N(e-)

analysis for discovery of p e 0
Analysis for discovery of p→e+π0

Tight momentum cut

⇒ target is mainly free protons

efficiency=17.4%, 0.15BG/Mtyr

free proton

bound proton

Small systematic uncertainty of efficiency

High detection efficiency

Perfectly known proton mass and momentum

No Fermi momentum

No binding energy

No nuclear effect

how the signal looks like
How the signal looks like

Proton mass peak

can be observed !

τp/B(p→e+π0) = 1×1035 yrs

S/N = 4 for 1×1035 years

S/N = 1 for 4×1035 years

τp/B(p→e+π0) = several×1035 yrs is reachable by a large water Cherenkov det.

physics reach
Physics Reach
  • Phase-I (0.77MW + 22.5kt):
  • NC interaction:Establish nmnt and limit on nmns
  • nmnm :dsin22q23 < 0.01

nmne :sin22q13 < 6×10-3 (90% CL)

nmnm :dDm232< 1×10-4eV2

at (sin22q=1.0, Dm2=3.2×10-3eV2)

  • Phase-II (4MW + 1000kt):

nmne :sin22q13 < 1×10-3 (90% CL)

nmne vs nmne : |d|>20 (3s discovery)

at (Dm122=5×10-5eV2 , Dm232=3×10-3eV2)

q 13 measurement superbeams vs reactor
q13 measurement:superbeams vs. reactor

P. Huber et al., hep-ph/0303232

400 tGWy

8000 tGWy

Systematics

Correlations

Degeneracies

to get funding for the 2 km detector

To get funding for the 2 km Detector?

To get additional funding for the Experimental hall + Detector (from KEK for JPY 2004?)

The availability of the candidate site for the 2 km detector

Realistic design and cost estimation of the detector hall

schedule 4 year plan
Schedule (4 year plan)

 KEK(~163 M$)

  • MEXT(Ministry of Education,Science and Technology)
  • Council for Science and Technology Policy

 Ministry of Finance

  • Need re-consideration for JFY 2004
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