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Strangeness Nuclear Physics at J-PARC. Kyungpook National University May. 26, 2009 Kiyoshi Tanida. Nuclear Physics. Study properties and reactions of nuclei. ~3000 found, >5000 should exist. neutron number. proton number. Why interesting?. I would give you just one example here.

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strangeness nuclear physics at j parc

Strangeness Nuclear Physics at J-PARC

Kyungpook National University

May. 26, 2009

Kiyoshi Tanida

nuclear physics
Nuclear Physics
  • Study properties and reactions of nuclei

~3000 found,

>5000 should exist

neutron number

proton number

why interesting
Why interesting?

I would give you just one example here...

  • Nuclear force
  • One pion exchange tail
  • Heavier mesonsNet attraction
  • Repulsive core (phenomenological)

V(R)

  • Quite different from molecularVan-der-Waals force
  • State dependent
  • Non-central forces (LS, tensor)
  • Isospin dependence

1 fm 2 fm

1 fm 2 fm

R

2π,σ,ρ,ω, ...

quarks

mesons

nuclear force cont
Nuclear force (cont.)
  • p is pseudscaler, i.e., Jp=0-
    • L changes when emitting/absorbingp

→ Mixing of L=0and L=2 (tensor force)

  • Bound state of NN exists only for Jp=1+, I=0(deuteron), where such mixing is allowed.

p

p

n

n

L=0 (S)

L=2 (D)

nuclei with strangeness
Nuclei with strangeness
  • Nuclei: many body systems of nucleons
    • which consist of up and down quarks→ p(uud), n(udd)
    • Actually, there are 6 quarks
  • Baryons with strangeness= HyperonsL=(uds), S+(uus), X0=(uss),...
  • Extended “space” of nuclei

u c t

d s b

hyper nuclear chart
Hyper-nuclear chart

Unexplored “space”

S=0 “surface”

physics
Physics?
  • New interaction
    • Extended nuclear force to flavor SU(3) world
    • Unified understanding of Baryon-Baryon force – What is its origin?
    • Is traditional meson exchange model enough?Need quark/gluon picture?
  • Property of hyperons in nuclei?
    • Hyperons can mix easily (e.g., LN-SN, LL-XN)→ Dynamical systems can be made
  • What happens to nuclei? Impurity effect?
    • Collective motion? High density matter?
slide8

S

B8B8(I)

1E, 3O (P=symmetric)

3E, 1O (P=unsymmetric)

NN(0)

NN(1)

(22)

(03)

‐1

LN

SN(1/2)

SN(3/2)

[(11)s+3(22)]

[3(11)s‐(22)]

(22)

[‐(11)a+(03)]

[(11)a+(03)]

(30)

LL

XN(0)

XN(1)

SL

SS(0)

SS(1)

SS(2)

(11)s+ (22)+ (00)

(11)s‐ (22)+ (00)

(11)s+ (22)

ー (11)s+ (22)

(11)s-    (22)- (00)

(22)

(11)a

[‐(11)a+(30)+(03)]

[(30)‐(03)]

[2(11)a+(30)+(03)]

‐3

XL

XS(1/2)

XS(3/2)

[(11)s+3(22)]

[3(11)s‐(22)]

(22)

[‐(11)a+(30)]

[(11)a+(30)]

(03)

XX(0)

XX(1)

(22)

(30)

B8B8 systems classified in the SU3 states with (l, m)

0

‐2

‐4

j parc
J-PARC
  • J-PARC = Japan Proton Accelerator Research Complex
  • Main accelerator: 50 GeV PS
    • 50 GeV×15 mA = 750 kW x100 of KEK-PS, x10 of BNL-AGS (~x10 of FAIR)
    • World leading facility with the ever strongest kaon beam
  • Construction almost done
    • First beam extracted from 50 GeV PS on Jan. 27
    • Strangeness nuclear physics experiments starts this year.
projects in j parc
Projects in J-PARC
  • Material & Life science (neutron, m)
  • Transmutation of nuclear waste
  • Nuclear Physics
    • Strangeness nuclear physics
    • Hadron spectroscopy
    • Nucleon structure
    • Hot and/or dense nuclear matter
    • Unstable nuclei
  • Particle Physics
    • Neutrino oscillation
    • Kaon rare decay
    • μrare decay
slide17

K1.8BR

K1.8

KL

K1.1

proposed experiments
Proposed experiments
  • 9 SNP experiments (out of 24)
    • All scientifically approved, 7 full approval, 4 Day-1
s 2 system
S=-2 system

E03:Measurement of X rays from X- atom Spokesperson – K. Tanida (Kyoto)

E05: Spectroscopic study of X-hypernucleus, 12XBe, via the 12C(K-,K+) reaction (Day 1 – 1st priority) Spokesperson – T. Nagae (Kyoto)

E07: Systematic study of double strangeness system with an emulsion-counter hybrid method

Spokespersons – K. Imai (Kyoto)

K. Nakazawa (Gifu)

H. Tamura (Tohoku)

E03

E05

E07

e03 experiment

Fe target

K-

K+

X-

X ray

E03 experiment
  • World first measurement of X rays from X-atom
    • Gives direct information on the XA optical potential
  • Produce X- by the Fe(K-,K+) reaction, make it stop in the target, and measure X rays.
  • Aiming at establishing the experimental method

X-

(dss)

Fe

X ray

physics motivation
Physics Motivation
  • Strangeness nuclear physics at S=-2
    • A doorway to the multi-strangeness system
    • Very dynamic system?
      • Large baryon mixing? Inversely proportional tomass difference.
      • H dibaryon as a mixed state of LL-XN-SS?
  • Little is known so far Main motivation of the J-PARC
importance of x systems
Importance of X systems
  • Valuable information on XN (effective) interaction
    • e.g., How strong XN  LL (and thus XN-LL mixing) is?
      • Relevant to the existence of H dibaryon
      • XN component in LL-hypernuclei
    • Exchange interaction is prohibited in one-meson exchange models
  • How about A dependence?
    • Most OME models predict large A dependence.
  • Impact on neutron stars
    • Does X- play significant role in neutron stars because of its negative charge?
    • S- was supposed to be important, but its interaction with neutron matter is found to be strongly repulsive.
principle of the experiment
Principle of the experiment
  • Atomic state – precisely calculable if there is no hadronic interaction
  • 1st order perturbation
    • If we assume potential shape,we can accurately determine its depth with only one data
    • Shape information can be obtained with many data
    • Even if 1st order perturbation is not good, this is still the same.
  • Peripheral, but direct (X-nuclei spectroscopy)
slide24

X atom level scheme

l=n-1 (circular state)

X

l=n-2

l=n-3

...

Energy (arbitrary scale)

...

Z

nuclear absorption

...

X

Z

...

l (orbital angular momentum)

X ray energy shift – real part

Width, yield – imaginary part

Successfully used for p-, K-,`p, and S-

experimental setup
Experimental setup
  • Long used at KEK-PS K2 beamline (E373, E522, ...)
    • Minor modification is necessary to accommodate high rate.
  • Large acceptance (~0.2 sr)

K-

K+

1.8 GeV/c

1.4x106/spill (4s)

x ray detector
X-ray detector
  • Hyperball-J
yield sensitivity estimation
Yield & sensitivity estimation
  • Total number of K-: 1.0x1012 for 800 hours.
  • Yield of X
    • production:3.7×106
    • stopped: 7.5×105
  • X-ray yield: 2500 for n=65 transition
    • 7200 for n=76
  • Expected sensitivity
    • Energy shift: ~0.05 keV (systematic dominant)

 Good for expected shift (~1 keV, 4.4 keV by Koike ) < 5% accuracy for optical potential depth

    • Width: directly measurable down to ~ 1 keV
    • X-ray yield gives additional (indirect) information on absorption potential.
expected x ray spectrum
Expected X-ray spectrum

n= 65

shift & width

0 keV

expected x ray spectrum 2
Expected X-ray spectrum(2)

n= 65

shift & width

4 keV

e07 ll hypernuclei
E07 LL Hypernuclei

Hybrid emulsion method

  • Goal:
  • 10000 stopped X- on emulsion
  • 100 or more double-L HN events
  • 10 nuclides
  • Chart of double-L hypernuclei
production of ll hypernuclei
Production of LL hypernuclei

~10% of LL are

trapped in nuclei

Xp  LL

example event in emulsion
Example event in emulsion
  • Track length, thickness
    • PID/energy
  • Presume what are produced at each vertex
    • Then check consistency
    • Unique assignment issometimes possible
  • Calculate binding energyDBLL = BLL - 2BLgives net LL interaction
systematics of ll binding energy

X

X

p

n

p

n

Systematics of LL binding energy
  • DBLLmay different for each nucleus
    • For example by hyperon mixing effect

5LLHe

6LLHe

p

L

n

L

p

n

Enhanced

Suppressed

slide34
S=-1
  • E10: Production of neutron-rich Lambda-hypernuclei with the double charge exchange reaction Spokespersons – A. Sakaguchi (Osaka), T. Fukuda (Osaka E. -C.)
  • E13: Gamma-ray spectroscopy of light hypernuclei Spokesperson – H. Tamura (Tohoku)
  • E15: A search for deeply-bound kaonic nuclear states by in-flight 3He(K-,n) reaction Spokespersons – M. Iwasaki (RIKEN), T. Nagae (Kyoto)
  • E17: Precision spectroscopy of kaonic 3He 3d2p X-rays Spokesperson – R. S. Hayano (Tokyo), H. Outa (RIKEN)
  • E18: Coincidence measurement of the weak decay of 12LC and the three-body weak interaction process Spokespersons: H. C. Bhang (Seoul), H. Outa (RIKEN), H. Park (KRISS)
  • E22: Exclusive study on the LN weak interaction in A=4 L-Hypernuclei Spokespersons: S. Ajimura (Osaka), A. Sakaguchi (Osaka)
mysteries about pentaquark q
Mysteries about pentaquark Q+

u

  • Does it really exist?
    • Need confirmation/rejection
  • Width? Why so narrow?
    • No doubt < 1MeV
    • Not observed in K+n elastic scattering/charge exchange
  • Spin-Parity?
    • 1/2+?, 3/2+?, 1/2-?, ....
  • What is the nature?

d

`s

d

u

LEPS 1st publication

confirmation of q
Confirmation of Q+
  • High resolution  width
  • First exp. @J-PARC: E19(Spokesperson: M. Naruki)
    • p(p-,K-)Q reaction
    • A good resolution:~2 MeV (FWHM)expected thanks toK1.8 beamline and SKS
    • Sensitivity: ~ 100 nb/sr
    • Stage 2 approved: Day-1
    • Even better resolution ispossible (~0.1 MeV)
q hypernuclei
Q Hypernuclei?
  • Extend Baryon-Baryon interaction to include anti-decuplets
  • May give a hint about the nature of Q+
    • For example, [D. Cabrera et al., nucl-th/0407007] calculated self-energy of Q-KN channel (i.e., K-exchange) weak, not enough to give bound states
    • If Q-KpN channel is taken into account, strong binding can be obtained (cf. N(1710) strongly couples to Npp)
    • There are many other scenarios...
  • Well, it’s interesting in itself, isn’t it?
production methods
Production methods?
  • (K+,p+) reaction: Proposed by Nagahiro et al.[PLB 620 (2005) 125]
    • Momentum transfer ~500 MeV/c
    • Elementary cross section: < 3.5 mb/sr (KEK-PS E559)[Miwa et al., arXiv:0712.3839]... Not good
  • (p-,K-): Momentum transfer ~1 GeV/c small cross section (< a few mb/sr: E522)

We propose (K+,p) reaction

[K. Tanida and M. Yosoi, J-PARC LOIhttp://j-parc.jp/NuclPart/pac_0801/pdf/LOI_Tanida_pentahyper.pdf]

the k p reaction
The (K+,p) reaction
  • Elementary process d(K+,p)Q+
  • Small momentum transfer
  • High resolution missing massspectroscopypossible

n

Θ

K

p

status and prospects
Status and prospects
  • First beam successfully extracted in Jan. 2009
    • To K1.8BR beamline
  • Expected schedule
    • Apr.-Sep., 2009 (now): fast extraction for neutrino exp.Finishing K1.8 beamline construction
    • Oct.-, 2009: commissioning of K1.8, E15&17@K1.8BRbeam intensity: ~1% of designed value
    • 2010~: experiments at K1.8starting from experiments using pions (E19, 18, 10, 22)10%~full intensity
    • E03: 2011?
silicon strip detectors
Silicon Strip Detectors
  • J-PARC beam intensity
    • 106~107/s for K-, much more for pions
  • Rate limit for gas-wire chambers
    • We are going to use 1 mm MWPC105 cps/mm  ~5 x 106 cps (rms beam size ~ 20 mm)
    • Tracking detectors are the bottle neck
  • SSD: even finer pitch (~50 mm) up to 108 cps possible
    • Higher position resolution is a favorable side effect.
requirements for ssd
Requirements for SSD
  • Strip pitch < 100 mm
  • Timing resolution < 10 ns
    • Expected accidental hit rate: < 1 at 108 cps
  • Detector size: > 60 x 20 mm2
    • Covering K1.8 beam size (rms: 20 x 3 mm2)
  • High radiation tolerance
    • Stable operation for > 1 month at 108 cps

We are developing SSD that satisfy those requirements

ssd sensor
SSD sensor
  • Developed for ATLAS collaboration
  • Thickness: 285 mm
  • Effective area: 62 x 61 mm2 – OK
  • Strip pitch & number80 mm x 768 strips
  • High radiation tolerance
    • up to 3 x 1014 p/cm2for 24 GeV/c protons
    • > 3 months with 108 cps
  • DSSD not available – Hamamatsu has withdrawn
    • Can KNU help?
readout apv25
Readout – APV25
  • Developed by CMS collaboration
  • Preamp. + shaper + multiplexer
    • 128 ch/chip
    • Quite similar to IDEAS VA1
  • Shaping time ~ 50 ns
  • Multiple sampling with 40 MHz clock time resolution: ~3 ns
  • High radiationtolerance

peaking time

hybrid board
Hybrid board
  • Sensor + 6 APV25 chips
  • 1st prototype under construction  coming soon

Rin-ei (林栄),Japan

slide48
DAQ
  • APVDAQ system – developed by HEPHY, Wien
summary
Summary
  • Utilizing the world ever-strongest kaon beam at J-PARC, we are planning to attack S=-2 sector.
    • E03: precision spectroscopy of X-atomic X rays to study XA interaction
    • Many other SNP experiments are planned
  • S=+1 hypernuclei might be accessible
    • Confirmation experiment first
    • Need detailed experimental design for hypernuclei
  • Silicon strip detector
    • Up to 108 cps Important for the highest beam intensity at J-PARC
    • Developing a prototype with ATLAS sensor + APV25 chip
    • Sensor is a problem for DSSD