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核子

通常の核

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ハイパー核

Magnetic Moments of Hypernuclear states

Ultimate goal of my hypernuclear experiments

K. Nakai (IIAS)

Motivated by Akito Arima

　　　 τ= 2.6 x 10-10 sec　　　　 μ 〜 μ(Λ) = - 0.613 nm

B = 20kG 　 　⇨ ωτ = 0.03 rad = 1.7 ゜

5ΛHe

Stimulated by Gene SprouseAtomic Hyperfine Field

　 Bhf(H:2S1/2) = 334 kG

　 Bhf(5ΛHe+) = 23 x 334 kG = 2,670 kG

⇨　 ωτ = 40.8 rad = 234 ゜

Can’t you measure hypernuclear magnetic moments ?

In a TEMPURA restaurant at Ikebukuro.

1994 Internationa Symposium at Riken in honor of Akito Arima

“Frontiers of Nuclear Structure Physics”5

ΛHe

F

I

J

H cosωt1

Rotating FrameLaboratory Frame

ν0I

JF

Hyperfine Frequency

　 ν0 (5ΛHe+) = 23 x 1,420 MHz = 2,500 MHz

Resonance Width (natural)

　⊿ ν= 1/(2πτ) = 600 MHz

(⊿ν/ν0) = 24 %RF Power

ω1τ= ｇ FH1μB/ h ≧ π

　　 ⇨ H1 ≧ 1 kG　

ω=ω0=2πν0F

I

J

5ΛHe

F

I

J

Target technology Li vapor in 2.5-GHz cavity Thin cavity-window for emitted particles

6Li + X → 5ΛHe + p + K+ + X’

( p + p → Λ+ p + K+ )

GSI, 2-GeV/N 6Li-ion beam

π+ + 6Li → 6ΛLi + K+

└→ 5ΛHe ＋ pKishimoto et al.

J-PARC: 3-GeV Ring

K ー + 6Li → 6ΛLi + π ー

└→ 5ΛHe ＋ p

J-PARC: 50-GeV Ring

Production of the 5ΛHe Generation of the 5

ΛHe+

Slowing down of the GeV 5ΛHe+ +

XX

Well studied by Kishimoto et al.

Larger (K,π)cross section

Earlier start-upPulsed πbeam

Sufficient time for preparation

？

？

◎

○

○

？

Electron sticking in a ring

5ΛHe+

Challenge !

Challenge !

μ(Λ) = ー 0.613 ± 0.009

μ(ΛHe) = ? ? ? ± 0.06(?)5

Theoretical (1) Saito,-Oka-Suzuki, Nucl. Phys. A625(1967) p.95 　 - 9% (2) Nemura-Akaishi-Suzuki, PRL89(2002)142504 　 (3) Toki

Experiental Spin-Dependent Λ Ｎ Interactions (Following arguement )

Predictions ???

Spin-Dependent Λ Ｎ Interactions

1979 Pirner1982 Pirner and Povh

CentralNN

CentralN VV

3

2=Λ （ Central force ）

0≈ΛLSNV （ L-S force ）

ΛN interaction

Hypernuclear Exp.

1978 Heidelberg-Saclay Coll. at CERN

0≈ΛLSNV

uds

0

udu

2

1Λ

N

LSNN

LSN VV ≥Σ

1988 YazakiLS

ΣNVLS

N NV ＜

Quark cluster model

Confirmed byKEK and BNLExperiments.

∞∞

∞∞

Gluon and quark combined exchange

SCITIC

3“Φx3” NAI

60Co Can you see the scintillation light ?

Eye needs 10 photons to recognbize

6mmΦ Iris

30 cm

20ev/photon

SCIntillation Track Image Camera

p → KΣProduction)

Σp → Σp Scattering)

n → KΛProduction)

Λp → Λp Scattering)

Analyzing PowerΛpScattering

PΛ=900MeV/cfss2FSS

-0.75±0.45125 - 150

0.00±0.27100 – 125

0.42±0.2375 – 100

0.96±0.2050 – 75

0.75±0.3225 – 50

Analyzing PowerΣCM (degree)

0.00±0.35105 – 135

-0.14±0.1975 – 105

-0.18±0.3145 – 75

-0.08±0.3015 – 45

Analyzing PowerΛCM (degree)

81evnets 67evnets

ΣpScattering

PΣ=900MeV/c

fss2FSS

Kyoto Model

Kyoto Model

∞∞

∞∞

Gluon and quark combined exchange

∞∞

∞∞Χ

No s-quark vs. u,d-quark interaction

uds

Λ-spin behaves like a spectator