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ΛXi-Hypernuclei and Experiments @ J-PARC

(J-PARC Hadron Salon)

Kazuma Nakazawa

Outline1. Introduction….neutron star & YN, YY interaction

2. Present knowledge on S=-2 system, eps. Xi-N. 3. Coming E07 experiment @ J-PARC

and The KISOevent showinga deeply-bound Ξ-N system

E03 and E05 experiments

4. Summary

Phys. Dept., Gifu Univ., JAPAN04th Aug., 2015

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Λ Cosmos (neutron stars)

Kazuma NAKAZAWAFaculty of Ed. & Graduate school of Eng.

Jul. 16th, 2015

http://kajipon.sakura.ne.jp/haka/schoenberg.jpg

http://kajipon.sakura.ne.jp/haka/beethoven19.jpg

Schubert’s grave

Beethoven’s grave

Discovery of doubly strange nuclei

studied by microscope

1Lecture for MC1

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Λ

http://blog-imgs-54.fc2.com/s/o/n/sonokininatte55/2013031423314880c.jpg

At the beginning of space,

every material disintegrates

in an elementary particle for

a high temperature. There-

fore particle physics is indis-

pensable for the early days

of the Big Bang space and a

study of the wound life of

the space.

佐藤勝彦 宇宙論入門 岩波新書(2014) p.44-45

Microscopic quantum theory and Cosmology

uroboros(S.L. Glashow，Novel Prise [1979])

Great wall

galaxy

solar system

sun

Earth

Human

Ameba

Molecule

AtomAtom

2Lecture for MC1

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Λ

History of the Universe（from beginning to now）

Unified force theory of particle physics gave an importantkey called the inflation in big bang theory. …However, itbecomes the future issues to get the theory established as aprobable theory. 佐藤勝彦 宇宙論入門 岩波新書(2014) p.112

10-44 s 1032 ℃ birth of Gravity10-36 s 1028 ℃ birth of Strong force

10-11 s 1015 ℃ : birth of Weak /ElectroMagnetic force

10-4 s 1012 ℃ : Quantum-mechanical phase transition0.01 s 1011 ℃ : birth of Elementary particle & Lighta few min 109 ℃ : formation of light nuclei

3x105y Cosmos clear up (Light gets through)

Gas gathers in many place, heavenly bodies are formed.

137±2x108y 2.7K[-270℃] Now

birth of fire-ball cosmos

Perio

dof i

nflatio

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3Lecture for MC1

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Λ

１．Introduction

vanKerwijk 2010

Romani et al. 2012

Demorest et al. 2010

Antoniadis et al. 2013

Neutron star mass (M◎)

J. M. Lattimer (2013)

Recent topics of NS＊ Observation of heavy NS (~2M◎)

＊ Hope to measure radius and mass of NS, coincidently.

＊ Detection of fast cooling of NS ①P. B. Demorest et al., Nature 467 (2010) 1081

PSR J1614-2230 (NS-WD binary), 1.97 ± 0.04 M◎

②J. Antoniadis et al., Science 340 (2013) 448PSR J0348+0432 (NS-WD binary), 2.01 ± 0.04 M◎

Mass (1~2)M◎

Radius (10~20)kmTemperature ~106 K [surface]

~108 K [internal]Pressure (1029~1031) atm [center]Density ~106 g/cc [surface]

~1015g/cc [center]cf. ~1014g/cc for 12C, 5.5 g/cc for earth,

1.5 g/cc for sun.

Profile and structure of Neutron Stars (NSs)

462 /

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Λ1) Hyperons will be mixed in NS.＊ Density ρ becomes large

chemical potential of neutron becomes large YN-mixing (Λn, Σ-n + e-)

start at ρt(Λ)～5ρ0 (ρ0 ~ 0.17fm-3)if YN interaction is attractive, ρt is decreasing to (2～3)ρ0.

2) Necessity of “Extra Repulsion” in hypernuclear system.＊ ρ > ρt(Λ) “softening” of EOS by increasing hyperons

keeping heavy mass of NS becomes hard.Introduction of three body force into hypernuclear system

makes ρt rebound to ~4ρ0.

Hyperons in NS463 /

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Λ

Interaction

Σ--nucleus potential is strongly repulsive.[KEK-PS E438 P. K. Saha et al., Phys. Rev. C 70 (2004), 044613.]

Bary

on fr

actio

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J.Schaffner-Bielich, N.P. A 804 (2008) 309-321「Hypernuclear physics for neutron stars」

== YN interaction ==

1. Universal three body force.

NNN, YNN, YYN, YYY int.,where Y = Λ, Σ, Ξ

Discovery of heavy NS (~2M◎)For extra repulsive forces,

2. Phase transition of baryon to quark matter.

3. ・・・：：

ESC08c(YN)+MPP(YNN)+TBA(YNN)

ESC08b(ΣN)

Y. Yamamoto, “workshop of neutron star”, Mar. 13th, 2015 @YITP

flavor independent !

Many theorists present many theories.百科争鳴

It is necessary for more rich informationof YN & YY int.

4 / 46

MNS < 1.4M◎

0.17

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ΛMain subject : Study of hadron-hadron interaction

Baryon octet・N-N interaction

Continuous research has been made in experiment and theory for more than 50 years

・ Y-N interaction, where Y = (Σ, Λ) Steadily progressing, e.g. γ-ray spectroscopy.

Next subject

Nuclear Phys. with S=-2

In S=-2 sector, YY-mixing [ΛΛΞNΣΣ(H)]

･ m(ΞN) – m(ΛΛ) = (23~28) MeV ･ m(ΣN) – m(ΛN) = 80 MeV

For those information, uniquely available source; double-Λ hypernucleus, Ξ hypernucleus,(H-dibaryon)

5 / 46

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Λ* Making a nuclear chart of double-hypernuclei

=> Information of Λ-Λ and Ξ-N force, for understanding B-B int. in SU(3)f

guides us to Multi-strangeness system, “strange matter”Key values of experiment: and BΞ-

Stra

ngen

ess

[N-Star/Strange Matter]

( )( )

NAGARA event

Unstable NuclideStable Nuclide

3D nuclear chart

One of the most powerful methods for the detection of DHN→ Emulsion experiment !!

However, it is hard to carry out any Λ-Λ and Ξ-N scattering experiment due to their very short lives.

Nuclear Phys. with S=-26 / 46

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Λ

via Ξ atom Direct process

=>

+

−K

Ξ−

Ξ −atom A *(S= −2)

Ξ−

Hor

Λ

Λ

Λ

ΛΛorH

Ξ− pΛΛ+28MeV

Λ

K

ΛΛ

A

−K Ξ−

K

ΛΛ

ΛΛ

+

K+

oπ

ΛΛ

ΛΛ

−K

H

p p

K+

−K

+

Ξ

K−K

orH (?)Ξ−

ΛΛ

K−K

+

How to input double strangeness into nucleus

2. Present knowledge on S=-2 systemwith nuclear emulsion

7 / 46

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Λ・ pK-=1.67 GeV/c

Q.F. ‘p’(K-,K+)Ξ-

・ The target, ==> Diamond

・ following Ξ- cand. track, ~103 Ξ- stopping.

(estimated)

The E373 experiment @ KEK(K-,K+) reaction

E373 setup

8 / 46

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Λ

5

6ΛΛ He

4He

t

Ξ-

p

π-

Λ He

10μm500

10

5

Ξ-

−ΛΛΛ ++→ πpHeHe 56

t++→Ξ+ ΛΛ− HeHe C 4612

theNAGARA event

J.K. Ahn ,et al., Phys. Rev. C 88, 014003 (2013).

if we take into account B Ξ− = 0.13 MeV [atomic 3D : 12C- Ξ− ]

cf. a previous paper ; H. Takahashi et al., PRL(2001) BΛΛ = 7.25 +/- 0.19 MeV, ΔBΛΛ = 1.01 +/- 0.20 MeV

BΛΛ = 6.91 +/- 0.16 MeV, ΔBΛΛ = 0.67 +/- 0.17 MeV6 HeΛΛ

9 / 46

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ΛBΛΛ and ΔBΛΛ

11 BeΛΛ

10 Be*ΛΛ

6 HeΛΛ

6 HeΛΛ

13 BΛΛ

NAGARA

MIKAGE

DEMACHI-YANAGIHIDA

E176

A ZΛΛΞ -

Captured

12C

12C

12C

14N

16O

BΛΛ - B Ξ− ΔBΛΛ - B Ξ−

[MeV] [MeV]

BΛΛ = 6.79 + 0.91B Ξ− (+/- 0.16)

ΔBΛΛ = 0.55 + 0.91B Ξ− (+/- 0.17)B Ξ− < 1.86

20.60+/- 1.27

2.38 +/- 1.34

9.88+/- 1.71

3.64+/- 1.71

11.77+/- 0.13

-1.65 +/- 0.15

------ -------

3D

3D

3D

3D

Assumedlevel

3D

BΛΛ ΔBΛΛ[MeV] [MeV]

23.3+/- 0.7

0.6+/- 0.8

11.90+/- 0.13

-1.52 +/- 0.15

20.83+/- 1.27

2.61 +/- 1.34

10.01+/- 1.71

3.77 +/- 1.71

6.91+/- 0.16

0.67 +/- 0.17

12 BeΛΛ22.31

+/- 1.21------ ------3D 22.48

+/- 1.21

M.Danysz et al., PRL.11(1963)29;R.H.Dalitz et al.,

Proc. R.S.Lond.A436(1989)1

10 BeΛΛ9 Be*Λ-> ------ ------- Recon.

atDecay

13 C*Λ->14.7

+/- 0.41.3

+/- 0.4Ex = 3.0

Ex = 4.9

cf. Ex = 2.8 cf. Ex = 2.8

By checking consistency of ΔBΛΛ (NAGARA) within 3 STD.,

11 BeΛΛ 14N21.95

+/- 2.673.73

+/- 2.7122.12

+/- 2.673.94

+/- 2.713D

Theoretical calculations:# 4-body Cluster …A=7-10 DoubleΛ. Hiyama et al., PRC66 (2002) 024007# 5-body Cluster Structure…11

ΛΛBe. Hiyama et al., PRL104 (2010) 212502

K.Nakazawa and H.Takahashi, PTP. Suppl.185 (2010) 335J.K.Ahn et al., Phys. Rev. C88 (2013) 014003

S.Aoki et al., N.P. A828(2009)191

3D

3D

3D

3D

3D

3D

3D

10 / 46

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Λ Ξ-nucleus interaction can be studied via Ξ hyper-nucleus and Ξ atoms. However non conclusive measurement has been made, so far.

Our knowledge is very limited.

@ BNL, KEK ・Any peak structures for Ξ-nuclear state were not observed.

・Attractive potential on 1Ξ2Be was suggested

to be ~14 MeV.・Two events (E176)

… 3D atomic or nuclear p bound state?・One event (E373)

… consistent with the Ξ- capture in 3D orbit.

Regarding Ξ-N potential, ~~~

Our knowledge on Ξ-N interaction11 / 46

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Λ

Woods-Saxon well depthof Xi-Nucleus potential

1) D. H. Wilkinson et al., PRL. 3, 397 (1959); 2) A.Bechdolff et al., PL. 26B, 174 (1968); 3) J. Catala et al., Proc. of Int. Conf. on Hyp. Phys., Argonne, 1969 (unpub.), Vol. 2, p.758; 4) A. S. Mondal et al., NC. A 54, 333 (1979).

C. B. Dover and A. Gal, Ann. Phys. (N.Y.) 146, 309

(1983).

Y. Yamamoto, Motoba, Fukuda, Takahashi & Ikeda PTP., Suppl. 117, 281 (1994)

(1994).

V0Ξ ~ -16 MeVV0

Ξ = -(21~24) MeV

K- interaction Two ΛA were prod.two step prod. can not be omitted. Ξ- stopping Twin ΛA pair prod.

The first observations of clearly identified Ξ-bound systems.

E176 @ KEK-PS

by Ξ-12C

VΞ = V0Ξ (1+e(r-R)/a)-1

R = roA1/3, a = 0.65 fm, ro = 1.1 or 1.25 fm

VΞ = V0Ξ (1+e(r-R)/a)-1+ VLS + Ucoul(r)

R = ro(A-1)1/3, a = 0.65 fm, ro = 1.1 fm

Ξ−+12C 4ΛH (#A) + 9ΛBe (#B) 0.54±0.20

4ΛH* (#A) + 9ΛBe (#B) 0.35±0.20

BΞ− (MeV)

S. Aoki et al., Prog. Theor. Phys. 89, 493 (1993).

12 / 46

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Λ

Xi-Nucleus potential

2) S. Aoki et al., Phys. Lett. B 355, 45 (1995).

Y. Yamamoto, Few-Body Syst., Suppl. 9, 145 (1995); K. Nakazawa, T. Sasaki, and Y. Yamamoto, in Proc. Hyp. Phys., Genshikaku Kenkyu 41, No. 6, 75

V0Ξ = -(16~17) MeV

Two events : Twin ΛA pair prod.

E176 @ KEK-PS

by Ξ-12C

Attractive parts : β1 = 2.0 fm, β2 = 0.9 fm,1= -2.5 MeV, 2= -166 MeV.Repulsive part : β3 = 0.5 fm, 3= parameter

吸収反応 生成核#13-11-14 #10-9-6

BΞ− (MeV) χ2 BΞ− (MeV) χ2

Ξ− +12C=> 4ΛH + 9ΛBe 3.89 ± 0.14 1.3 ◎ 0.82 ± 0.17 0.4

4ΛH* + 9ΛBe 2.84 ± 0.15 ○ -0.23 ± 0.17

4ΛH + 9ΛBe* ◎ 0.82 ± 0.14

4ΛH* + 9ΛBe* ○ -0.19 ± 0.15

Ξ− +14N=> 4ΛH + 1Λ1B 3.55 ± 0.15 3.5 0.79 ± 0.17 8.0

4ΛH* + 1Λ1B 2.50 ± 0.15 -0.26 ± 0.18

Ξ− +16O=> 4ΛH + 1Λ3C 9.90 ± 0.18 11.2 7.48 ± 0.21 19.5

4ΛH* + 1Λ3C 8.85 ± 0.19 6.43 ± 0.21

4ΛH + 1Λ3C* 5.0 ± 0.2 2.6 ± 0.2

4ΛH* + 1Λ3C* 3.9 ± 0.2 1.5 ± 0.2

4ΛH + 1Λ3C* a) 0.3 ± 0.4

4ΛH* + 1Λ3C* b) -0.8 ± 0.4

#10-9-6

#13-11-14

1) S. Aoki et al., Prog. Theor. Phys. 89, 493 (1993).

S. Aoki et al., Nucl. Phys. A 828, (2009) 191.

Nijimegen Model D G-matrix interaction VΞ = ∑ iexp(−( /i) )

Well reproduce 2p state : BΞ− = 0.58 MeV

S.Tadokoro, H.Kobayashi and Y.Akaishi, Nucl. Phys. A585, 225c (1995)

Green Function

(1995).

V0Ξ = -16 MeV by Ξ-12C

13 / 46

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Λ

T. Fukuda et al., PR. C 58, 1308

(1998).

V0Ξ > -20 MeV

E224 @ KEK-PS12C(Κ−, Κ+) int.

Missing mass spectrum

J. K. Ahn et al., Phys. Lett. B 378, 53 (1996).

E885 @ BNL-AGS

-16 MeV-20 MeV-24 MeVV0

Ξby Ξ12Be

・・・ reasonable agreement between the dataand theory is achieved by assuming a Ξ-nucleus potential well depth V0

Ξ of about -14MeV within the Woods-Saxon prescription.

P. Khaustov et al., PR. C 61, 054603

(2000).

by Ξ12Be

12C(Κ−, Κ+) int.Missing mass spectrum

Xi-Nucleus potential 14 / 46

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n

ΛΞ-nuclei vs. H-nucleus

Λ＋Λ

Ξ−＋p

28.62

KISO event

Λ5He＋1

Λ0Be

(14339.265)

Ξ−＋14N (14361.912)

22.65

g.s.

BΞ−=4.378 MeV

18.27

28.6218.6 MeV

~ 10 MeVΛ＋Λ

Ξ−＋p

H

H nucleus

Λ5He＋1

Λ0Be

(14339.265)

Ξ−＋14N (14361.912)

22.65

g.s.

seems to be BΞ− ~ 18 MeV

~ 4 MeV

If H nucleus was formed (M[H] - M [ΛΛ] ~ 10 MeV)

16 / 46

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n

Λ

@ J-PARC (coming soon)

・E07 … ~103 double-Λ hypernuclei and ~102 Ξ-nucleus

・E03 & E07 … X-ray measurementfrom Ξ atoms.

・E05 … High reso. spectr. of Ξ hypernuclei.

To get more informtion17 / 46

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Λ

kDepartment of Physics, Toho University, Japan,lKEK, High Energy Accelerator Research

Organization, Japan,mDepartment of Physics, Nagoya University, Japan,n Gyeongsang Nat'l University, Korea,oSeoul National University, Korea,pResearch Center for Nuclear Physics (RCNP),

Japan,qMandalay University, Myanmar,rYadanabon University, Myanmar,sUniversity of Fukui, Japan,tShanxi Normal University, China.

K.Imaia, K.Nakazawab, H.Tamurac, S.Ahmadd, J.K.Ahne, B.Bassalleckf, R.E.Chrieng, H.Ekawai, Y.Y.Fuj, S.Fukunagak,Y.Hanf, R.Hasand, S.Hasegawaa, E.Hayatai, M.Hirosei, K.Hoshinob, K.Hosomia, S.Hwanga, M.Ieiril, H.Itob,K.Itom,

K.Itonagab, T.Kawaim, J.H.Kimn, S.Kinbarab, R.Kiuchio, T.Koikec, H.S.Leee, J.Y.Leeo, C.Lij, Z.M.Lij, K.Miwac, H.Noumip,S.Ogawak, S.Y.Ryue, H.Sakoa, S.Satoa, T.Satom, M.Sekimotol, H.Shibuyak, K.Shirotorip, M.K.Soeq, H.Sugimuraa, M.Sumihamab, H.Takahashil, T.Takahashil, K.Tanidao, A.M.M.Theintq, K.T.Tintr, A.Tokiyasup, M.Ukaic, T.Watabem,

T.Yamamotoc, N.Yasudas, C.S.Yoonn, J.Yoshidab, T.Yoshidas, D.H.Zhangt, J.Zhouj, S.H.Zhouj, and L.H.Zhuj

aJapan Atomic Energy Agency (JAEA), Japan,bPhysics Department, Gifu University, Japan,cDepartment of Physics, Tohoku University, Japan,dAligarh Muslim University, India,ePusan National University, Korea,fDepartment of Physics and Astronomy,

University of NewMexico, USA,gBrookhaven National Laboratory, USA,hUniversity Colledge of London, UK,iDepartment of Physics, Kyoto University, Japan,jCIAE, China Institute of Atomic Energy (CIAE),

China,

To obtain rich information about ΛΛ & ΞN interaction. !!

JPN：９／KOR：３／MYM：２／CHN：２／USA：２／UK：１／IND：１・・・・・・・・２０ Univ.・Inst.

３．The E07 experimentand the KISO event

18 / 46

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Fully automatic detection of

3 vtx. event

like NAGARA event, KISO event

10 times statistics of that

with the hybrid method

1.New Hybrid method 2. Overall-scanning

J-PARC１．Pure K-beam

( better 3.5 times than KEK-PS)２．More emulsion volume ( x 3 )

103 (E373) 104 Ξ- stop events１．X ray measurement from Ξ atom

with Hyperball-X study of Ξ-N interaction

２． ～102 double hypernuclei

Measurement of the mass of

～103 double hypernuclei

～102 Xi hypernuclei

with A<16

(1/0.3): free from x4 :･’p’(K-,K+)Ξ- in the emulsion･’n’(K-,K0)Ξ- reaction

Strategy of E07@J-PARC

acceptance & tracking

Automated track-following

19 / 46

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Development of “Automated track-following”

Upper face

Down face

Up

Down

#iBeam

#(i+1)

Base

Base

E373 : alignment of plate by plate

~ 0

.10m

m [Grid Mark]Accuracy :

~ 17+/- 9μm/ 24.5×25 cm2

Detected multi-candidates

Alignment accuracy has achieved: 1.1 +/- 0.1 μm / 24.5×25 cm2

Automated track-following

~ 0

.10m

m

~ 90 s, Now

20 / 46

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OS ：Win2000 sp4CPU ：3.0 GHz

1.57GB RAMCamera ：100Hz (CCD)Obj. lens：x 50emulsion： 500μmarea ：0.1x0.08mm2

# of image：~100/cycle Time ：5min. /cycle

3sec/cycle[~ hard limit]

Development of “Overall-scanning”

① fast image captureDeveloped systemwith CCD camera

Primary motivation; fast detection of α decay vertices of natural isotopes to calibrate range-energy relation.

21 / 46

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Until April. 2013, 8 M images under test operation (1.46 cm3)

using E373 emulsion (55 liters)

② fast image processing

Double-Λ

NAGARA eventwas detected by this method

2 vertices (single-Λ cand.)

more

for event detection

α decay VTX

3 vertices

Development of “Overall-scanning”

22 / 46

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Topology seems to be consistent with the past events of twin hypernuclei (E176).Emitted back-to-back direction

An event by the “Overall-scanning”,named“KISO”

Results of KEK-E176:S.Aoki et al., NP. A828 (2009) 191-232

23/ 46

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Image of the KISO event

24 / 46

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Range-Energy relationwas calibrated in good accuracy

Proton for Std. emulsion(Ilford G5 : 0 = 3.815 g/cm3);

ref.[1] W.H.Barkas, N.C. VIII (1958) pp.201-214

data fitted by polynomial expression under the Bethe-Bloch formula.

Calc. Our 7th order polynomial fitting to the ref.[1]

Density of our emulsion;= 3.621 +/- 0.105 g/cm3

by measurement of α rays with monochromatic K.E. from 212Po and 228Th.

Consistent with = 3.667 +/- 0.066 g/cm3

by measurement of its size and weightat the E373 beam exposure.

The density error of 0.105 g/cm3

gives rise inaccuracies,

ΔR / R : 1.1%ΔE / E : 0.7%

for proton to 12C with their energy

less than several tens’ MeV

25 / 46

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#4

Vertices A & B

AB

2) Auger electron make the capture point clear.

5) Consistent with Ξ- capture reactionoccurred on C, N or O.

1) Ξ- hyperon can be produced in the target (8 mm from top the Em.)

4) TK #4 went out of the emulsion stack.

E373 setup

[1] The charge of #2 should be 2 or more.

[2] The charge of #1 should be ≦ 5.

Outline of the KISO event

#4

[3] Hummer track : 8He, 8Li or 8B 8Be*(2+).

3) MIPS track from the decay point D.

26 / 46

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vtx track range (µm) theta (deg.) phi (deg.) comments

A#1 8.0 ± 0.3 133.0 ± 3.0 13.2 ± 3.2 Single-hypernucleus

77.1 ± 0.3 µm : B ~ C#2 69.1 ± 0.5 40.4 ± 0.9 193.1 ± 1.2

B#3 13.3 ± 0.4 102.3 ± 2.3 340.4 ± 1.6

#4 > 4990.7 145.0 ± 0.9 85.4 ± 1.3 Out of the emulsion stack

D#5 6.7 ± 0.3 49.6 ± 4.2 132.6 ± 4.3 α from

8Be

#6 5.8 ± 0.3 131.0 ± 4.5 318.9 ± 4.7 α from 8Be

C#7 2492.0 ± 3.9 43.1 ± 1.3 191.8 ± 1.5

#8 37.3 ± 0.7 131.9 ± 1.3 29.2 ± 1.3

Ranges and angles

Outline of the KISO event 27 / 46

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Analysis of the KISO event

0 5 10 (μm)

0

5

10

(μm

)

Mass of 8Be∗(2+)(MeV/c2 )

Reconstructed mass(MeV/c2)

(a) 7457.890(Γ = 1.5 MeV)

7458.531 ± 0.307(b) 7458.540 ± 0.308

Using measured data Under the momentum balance

Vertex D

π- possibility (#4) is nothing in comparison with Energy-loss(Grain density ~ x1.41[+/- 0.08]) of π- in the NAGARA event.

K.E. of #4 (34.8MeV, if it’s a proton ) was too large to understandthe decay mode with a π0 meson at the decay point of #1.

#4

Vertex B

D

B

Possibility of mesonic decay of #1 denied !!

8Be*(2+) → 2α at VTX. D

Non-mesonic decay at VTX. B

28 / 46

8B : charge conservation at VTX#A8He : mom. imbalance at VTX#A

p

n

Λ

#4

Vertex B

B

Possible process at VTX. B

Mc : Mass of a core nucleus + M(Λ)Mr : reconstructed minimum massMc -Mr : BΛmax. should be plus value.

The particle (#1) can be 1Λ0Be or 1Λ1Be.There is no bound hyperfragment for track #2

29 / 46

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Vertex A

The mode :was uniquely identified

Possible process at VTX. A

A

Ξ− + 14N 1Λ0Be + 5ΛHe

30 / 46

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Ξ− + 14N 1Λ0Be (#1) + 5ΛHe (#2),

1Λ0Be 8Li (#3) + p (#4) + n,

8Li 8Be*(2+) + e- (+ ν−e) 8Be*(2+) 2α (#5 & # 6)

5ΛHe p(#7) + d(#8) + 2n

Process of the KISO event

BΞ− = 4.38 +/- 0.25 MeV (by Mom. balance [#1 and #2])Measurement error : 0.09 MeVMass (1

Λ0Be, 5ΛHe, Ξ−) error : 0.23 MeV

ex.

＊Event interpretation and the energy of BΞ-31 / 46

p

n

ΛThe case of production of

1Λ0Be in excited state

BΞ− = M(Ξ−+14N) – E(1Λ0Be) – E(5

ΛHe)

[28] E. Hiyama and Y. Yamamoto, PTP 128, 105 (2012)[29] D. J. Millener, Nucl. Phys. A 881, 298 (2012)

32 / 46

p

n

ΛTheoretical predictions

9Be + Λ

1Λ0Beg.s.

Ene

rgy

(MeV

)

BΛ = 9.11 +- 0.22(exp.)

3.27 (1+)

BΞ− = 0

BΞ−

(MeV

)

0

10

5

5

0

1

2

3

4

H&Y DJMΞ−14Nsystem

3D0.174

The first evidence of a Ξ-14N system to be bound deeply.

2p

1s

Yam

aguc

hi, Y

amam

oto

& U

eda

PT

P.

105

(200

1) 6

27

1.14

5.69 The

pape

rw

ell

pres

ente

dth

atth

epa

sttw

oev

ent

tobe

occu

rred

in2p

nu

clea

rb

ou

nd

stat

e.

4.38±0.25

1.11±0.25

Err.(meas.)=±0.09Err.(mass)=±0.23

Ξ− + 14N 1Λ0Be + 5ΛHe uniquely identified!!

the KISO event

BΞ− = 4.38 +/- 0.25 MeV (by Mom. balance for 1Λ0Be and 5ΛHe)

3.07 (0+)2.41 (3-)2.36 (22

-)

0.08 (21-)

3.228 (1-)3.202 (0-)2.585 (3-)2.482 (2-)

0.110 (2-)

6.509 (4-)6.433 (3-)

(σerr ~ 0.25 MeV)3.7σerr far from 3D level

33 / 46

p

n

Λ

E176 results; S.Aoki et al., NP. A828 (2009) 191-232Ξ− binding energy (MeV) in nucleus : 12C [most probable]

Good agreement with

a theoretical prediction in the case of

Ξ− - 12C system

Comarison of E176 eventswith theoretical prediction

Table 9. Theoretical prediction of BΞ− values for the Ξ−-12C and

Ξ−-14N systems using Coulomb and Ehime potentials.

M.Yamaguchi, K. Tominaga, Y. Yamamoto, and T. Ueda, PTP 105, 627 (2001)

Published atK. Nakazawa et al.,Prog. Theor. Exp. Phys. 2015, 033D02DOI : 10.1093/ptep/ptv008

34 / 46

p

n

Λ

Present New

Obj. Lens ×50 (NA. 0.9) ×20 (NA. 0.35)

Camera 100Hz XC_HR300 800Hz HXC20

Pixel 512×440 pixel 2039×357 pixel

Area 130 mm×110 mm 1140 mm×200 mm

Rate(Hz) 0.3 5

Present system

130 μm

110

μm

200

μm

1140 μm

with piezo stage

Images of all of the emulsion can be obtained in a few years.

New scanning system for the E07emulsion

4 sets 3 sets

×300 faster !!

Introduced by Dr. J. Yoshida Jul.11th

35 / 46

• World first measurement of X rays from Ξ-atom– Gives direct information on the ΞA optical potential

• Produce Ξ- by the Fe(K-,K+) reaction, make it stop in the target, and measure X rays.

• Aiming at establishing the experimental method

K- K+

Ξ−

X ray

Fe targetΞ− (dss)

Fe

X ray

Outline of the E03 experiment36 / 46

l (orbital angular momentum)

Ene

rgy

(arb

itrar

y sc

ale)

...

...

...

...

l=n-1 (circular state)l=n-2l=n-3

nuclear absorption

Ξ atom level scheme

Z

Ξ

Z

Ξ

X ray energy shift – real partWidth, yield – imaginary part

37 / 46

K-

K+

Ξ-

E03 detectors

Hyperball-J CH

TOF

DC3

DC2DC1FAC

BH2

BAC

FBH PVAC

KURAMA

38/ 46

Acceptance & Efficiencies

• Beam momentum: 1.8 1.67 GeV/c– To match with E07 and save commissioning time

– Negligible impact to yield

• KURAMA gap is extended: 50 cm 80 cm– 60% increase in acceptance, 30% in stopped Ξ

• Mistake in estimation of Ξ stopping probability– Especially in large reaction angles

– 20% 15%: cancel the yield increase above

• Ge livetime: 50% > 70% at expected intensity– ~80% with present intensity

• Ge efficiency: Ge position to be optimized including livetime

4639 /

Hyperball-J in E13

E13 CF4 run

17F (197keV)

• Worked well• Livetime: ~80%

with K+π: ~500 k/spill• Resolution: 3-4 keV@197 keV

4640 /

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n

Λ

4641 /

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n

Λ

4642 /

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n

Λ

4643 /

p

n

Λ

4644 /

p

n

Λ

4645 /

p

n

Λ1. We have performed experiments to study S=-2 systems with the nuclear emulsion at KEK. However, very little is known, so far.

2. To get more rich information about S=-2 systems, which is quite important to understand the EOS of neutron stars and baryon octet scheme, we are developing fully automated and fast scanning method, “Overall scanning” for the emulsion.

3. During test operation of the system, a clear evidence of a deeply bound Ξ-14N system has been detected and uniquely identified, Ξ− + 14N 1

Λ0Be + 5ΛHe, in the

emulsion of 1.46 cm3 volume among 55 liters. The detected event, named “KISO”,presents Ξ− binding energy of 4.38 +/- 0.25 MeV, which is no longer the atomic 3D state (0.17 MeV for Ξ- atom on 14N). Theoretical predictions for Coulomb-assisted nuclear bound state for Ξ−-12C and Ξ−-14N agree the results of not only KISO, but also two events presented by the E176 experiment.

4. It was understood that ΞN interaction will be attractive!! To understand ΞN interaction more in detail, we will carry out the E07, E03 and E05 experiment with beam exposure being accomplished at J-PARC from 2016.

4. Summary4646 /