J-PARC 　 Day-1 実験の状況・

実験家から理論屋への要望T.Takahashi (KEK)

Contents1. Aproved Exp. on S=-2 @ J-PARC2. How to produce S=-2 Systems3. E05: (K-,K+) Spectroscopy4. Discussion

Approved Experiments

3 Exp. Proposals concerning to S=2 system were approved.

E03

E05

E07

Approved Proposals of the Investigation on S=2 Systems

• Spectroscopy study of -hypernucleus, 12Be,

via the 12C(K-,K+) reaction (E05)– Reaction (Missing mass) spectroscopy– -hypernuclei, -hypernuclei– -A potential at center region

• Measurement of X rays from - atoms (E03)– X-rays from - atomic states– -A potential at surface region

• Systematic study of double strangeness systems with an emulsion-counter hybrid method (E07)– Decay (Invariant mass spectroscopy)– X-rays from - atom– -hypernuclei, -hypernuclei

How to produce and studyS=2 systems

K + p K+ +

p(K)~1.8GeV/c

Direct productionReaction Spectroscopy

Decay measurementsEmulsion

X-rays measurements

q ~0.5 GeV/c

E05 Experiment

• Missing mass spectroscopy of 12C(K,K+)X– 12

Be, 12Be

• K1.8 beamline & SksPlus spectrometer– 1.8 GeV/c K & ~1.3 GeV/c K+

• Missing mass resolution of ~3 MeV/c2

– Energy and width of bound states

• To establish methodlogy on spectroscopy of S=2 systems

K1.8 beamline at J-PARC

E.S. Separators

BeamSpectrometer

K ~6.9

p/p=3.3x10(FWHM)

1.2x106 K /spill(Phase-1)

High-purity

High-intensity

High-resolution

Proton beam30GeV-9A

SksPlus Spectrometer

2.7T(395A)

~1.5T

• 95°total bend• ~7m flight path• x=0.3 mm (RMS)

0

10

20

30

40

1.0 1.2 1.4 1.6p [GeV/c]

[msr

]

~30msr

0.5

1.0

1.5

2.0

2.5

1.0 1.2 1.4 1.6p [GeV/c]

dp [M

eV/c

]

p/p=0.12%

Previous Measurement on 12C(K,K) – BNL AGS E885 –

PK=1.8 GeV/cM=9.9 MeV/c2 (FWHM) for p(K,K+)

P.Khaustov et al, PRC61(2000)0546

20 < E < 0 MeV 89±14 nb/sr < 8° 42± 5 nb/sr <14°

Evidence !? V = 14 MeV

12C(K,K+)12Be spectra

calculated by W.S. potential

P.Khaustov, et al.Phys. Rev. C61(2000)054603

V[MeV]

states

s-state [nb/sr]

0p3/20s1/2

p-states

0p3/20p3/2

0p3/20p1/2

sum

[nb/sr]

Edet=0 MeV

K.Ikeda, et al, Prog. Theor. Phys. 91 (1994) 747 ;Y.Yamamoto, et al,Prog. Theor. Phys. Suppl. 117 (1994) 281

Expected 12Be Spectrum

V= 20MeV

V= 14MeV

[cou

nts/

0.5M

eV]

-B [MeV]

s

p Emeas. = 3 MeVFWHM

One momth Data-taking

(K,K+) reaction spectroscopy

• 生成チャンネルを見る– 基底状態・励起状態の観測– 多くの標的への適応可能性– T = 1

• Spectroscopy が成立する条件– ≦M

– BY ＞ M)

– Level spacing ＞ M)

考えられるシナリオ• 細い（１本の）ピークを観測

– Small Imag. potential• Weak N interaction

– binding energy• Potential (Real) depth

• ピーク構造が観測されない– 　幅が広い– 　複数の状態が励起している。

• Spin-doublet• Core excited states

Spectroscopy が成立ー＞他の標的へ

理論の人に尋ねたい一緒に考えたいこと（１）

• どのような状態が考えられるのか？– 　 Spin 　 / 　 Isopin

• 生成断面積は？– 　素過程の amplitude

• spin-flip/spin-non-flip

• 幅が広いとき、核は直接反応でどの程度生成されるのか？

理論の人に尋ねたい一緒に考えたいこと（２）

• ＦＩＳを用いた N 相互作用の研究– K d K+ n– Kinematics Q.F. の End Point 近辺 ?– 断面積 0.1 b/(sr MeV) あれば可能？– どの位の分解能が必要か？

Kinematics of K d K+ n

K p n

d

Kn

0

500

1000

1500

0 0.05 0.1 0.15p [GeV/ c]

a.u.

Momentum Dist. in d

2-dim. simple model

0

0.2

0.4

0.6

0.8

1

- 0.15 - 0.1 - 0.05 0 0.05 0.1 0.15

pn [GeV/ c]

[GeV

/c]

1.8GeV/ c

1.5GeV/ c

2.0GeV/ c

Relative momentum between n and

Tokai Site of JAEA

Photo:21-Dec-2006

7-Feb-2007

23-Feb-2007

Photo:21-Dec-2006

23-Feb-2007