p - J-PARC分室

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n
p
Xi-Hypernuclei and Experiments @ J-PARC
Λ
(J-PARC Hadron Salon)
Kazuma Nakazawa
Outline
Phys. Dept., Gifu Univ., JAPAN
04th Aug., 2015
1. Introduction….neutron star & YN, YY interaction
2. Present knowledge on S=-2 system, eps. Xi-N.
3. Coming E07 experiment @ J-PARC
and The KISO event showing
a deeply-bound Ξ-N system
E03 and E05 experiments
4. Summary
Discovery of
doubly strange nuclei
Lecture for MC1
n
p
Λ
Cosmos (neutron stars)
studied by microscope
Kazuma NAKAZAWA
Faculty of Ed. & Graduate school of Eng.
Jul. 16th, 2015
Beethoven’
s grave
Schubert’
s grave
http://kajipon.sakura.ne.jp/haka/schoenberg.jpg
http://kajipon.sakura.ne.jp/haka/beethoven19.jpg
1
Lecture for MC1
n
p
2
Microscopic quantum theory and Cosmology
Λ
uroboros
(S.L. Glashow，Novel Prise [1979])
Great wall
galaxy
solar
system
Human
Atom
Atom
Molecule
sun
Earth
Ameba
At the beginning of space,
every material disintegrates
in an elementary particle for
a high temperature. Therefore particle physics is indispensable 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
http://blog-imgs-54.fc2.com/s/o/n/sonokininatte55/2013031423314880c.jpg
Lecture for MC1
n
p
Λ
3
History of the Universe
（from beginning to now）
137±2x108y 2.7K[-270℃] Now
Gas gathers in many place, heavenly bodies are formed.
Period of inflation
birth of fire-ball cosmos
3x105y Cosmos clear up (Light gets through)
a few min 109 ℃ : formation of light nuclei
0.01 s 1011 ℃ : birth of Elementary particle & Light
10-4 s 1012 ℃ : Quantum-mechanical phase transition
10-11 s 1015 ℃ : birth of
Weak /ElectroMagnetic force
10-36 s 1028 ℃ birth of Strong force
10-44 s 1032 ℃ birth of Gravity
Unified force theory of particle physics gave an important
key called the inflation in big bang theory. …However, it
becomes the future issues to get the theory established as a
佐藤勝彦 宇宙論入門 岩波新書(2014) p.112
probable theory.
2 / 46
n
１．Introduction
p
Λ
J. M. Lattimer (2013)
Profile and structure of Neutron Stars (NSs)
vanKerwijk 2010
Romani et al. 2012
Mass
(1~2)M◎
Radius
(10~20)km
Temperature ~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.
Recent topics of NS
Demorest et al. 2010
Antoniadis et al. 2013
Neutron star mass (M◎)
n
＊ 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) 448
PSR J0348+0432 (NS-WD binary), 2.01 ± 0.04 M◎
Hyperons in NS
3 / 46
p Λ
1) Hyperons will be mixed in NS.
＊ Density ρ becomes large
 chemical potential of neutron becomes large
 YN-mixing (Λn, 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.
4 / 46
Interaction
n
p Λ
== YN interaction ==
MNS < 1.4M◎
Σ--nucleus
Discovery of heavy NS (~2M◎)
For extra repulsive forces,
1. Universal three body force.
potential is strongly repulsive.
flavor independent !
NNN, YNN, YYN, YYY int.,
[KEK-PS E438 P. K. Saha et al., Phys. Rev. C 70 (2004), 044613.]
where Y = Λ, Σ, Ξ
Baryon fraction
ESC08b(ΣN)
ESC08c(YN)
+MPP(YNN)
+TBA(YNN)
Y. Yamamoto,
“workshop of neutron star”, Mar. 13th, 2015 @YITP
0.17
J.Schaffner-Bielich, N.P. A 804 (2008) 309-321
「Hypernuclear physics for neutron stars」
Nuclear Phys. with S=-2
n
p
2. Phase transition of
baryon to quark matter.
3. ・・・
：
：Many theorists present many theories.
百科争鳴
It is necessary for more rich information
of YN & YY int.
Λ
5 / 46
Main 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
In S=-2 sector,
 YY-mixing [ΛΛΞNΣΣ(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)
6 / 46
Nuclear Phys. with S=-2
a nuclear chart of double-hypernuclei
*nMaking
=> Information of Λ-Λ and Ξ-N force, for understanding B-B int. in SU(3)
p
Λ
f
guides us to Multi-strangeness system, “strange matter”
Key values of experiment:
and BΞ-
Strangeness
3D nuclear chart
[N-Star/
Strange Matter]
NAGARA
event
( )
( )
Unstable Nuclide
Stable Nuclide
However, it is hard to carry out any Λ-Λ and Ξ-N scattering experiment
due to their very short lives.
One of the most powerful methods for the detection of DHN
→ Emulsion experiment !!
7 / 46
n
p
2. Present knowledge on S=-2 system
with nuclear emulsion
Λ
How to input double strangeness into nucleus
 via Ξ atom
 Direct process
K+
K
K
−
K
−
Λ
−
Ξ
H
K+
−
K
pp
ΛΛ
K
K+
−
Ξ
Λ
+
K
K
−
Ξ− p
=>ΛΛ+28MeV
+
−
Ξ
Ξ
πo
Λ
Λ
K
−
ΛΛ
or H
K+
−
A
Ξ atom
−
A *(S= −2)
ΛΛ
ΛΛ
Ξ −or H (?)
Λ
Λ
or
H
Λ
Λ
Λ
Λ
The E373 experiment @ KEK
n
(K-,K+) reaction
8 / 46
E373
setup
Λ
p
・ pK-=1.67 GeV/c
 Q.F. ‘p’(K-,K+)Ξ・ The target,
==> Diamond
・ following Ξ- cand. track,
 ~103 Ξ- stopping.
(estimated)
the NAGARA event
n
12
Λ
p
9 / 46
C + Ξ − → ΛΛ6 He + 4 He + t
6
5
−
ΛΛ He → Λ He + p + π
πp
6
ΛΛHe
4
He
10
5
ΛHe
t
Ξ-
5
0
0
5
Ξ-
10μm
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− ]
6
ΛΛHe BΛΛ = 6.91 +/- 0.16 MeV, ΔBΛΛ = 0.67 +/- 0.17 MeV
cf. a previous paper ; H. Takahashi et al., PRL(2001) BΛΛ = 7.25 +/- 0.19 MeV, ΔBΛΛ = 1.01 +/- 0.20 MeV
K.Nakazawa and H.Takahashi, PTP. Suppl.185 (2010) 335
J.K.Ahn et al., Phys. Rev. C88 (2013) 014003
BΛΛ and ΔBΛΛ
n
Λ
p
10 / 46
By checking consistency of ΔBΛΛ (NAGARA) within 3 STD.,
BΛΛ - B Ξ− ΔBΛΛ - B Ξ− Assumed BΛΛ
ΞAZ
level
[MeV]
[MeV]
[MeV]
ΛΛ Captured
6 He
NAGARA ΛΛ
12C
ΛΛHe
12C
ΛΛBe
14N
6
MIKAGE
11
DEMACHIYANAGI
HIDA
ΛΛ Be*
12C
ΛΛBe
16O
ΛΛ Be
14N
10
11
12
E176
13
22.31
+/- 1.21
13 C*
ΛΛ B -> Λ
BΛΛ = 6.79 + 0.91B Ξ− (+/- 0.16)
ΔBΛΛ = 0.55 + 0.91B Ξ− (+/- 0.17)
B Ξ− < 1.86
9.88
3.64
+/- 1.71
+/- 1.71
21.95
3.73
+/- 2.67
+/- 2.71
-1.65
11.77
+/- 0.15
+/- 0.13
cf. Ex = 2.8
2.38
20.60
+/- 1.34
+/- 1.27
Ex = 4.9
------
0.67
+/- 0.17
10.01
+/- 1.71
3D
22.12
3.94
+/- 2.67
+/- 2.71
-1.52
11.90
+/- 0.15
+/- 0.13
cf. Ex = 2.8
20.83
2.61
+/- 1.27
+/- 1.34
22.48
-----+/- 1.21
3D
3D
3D
-------
3D
S.Aoki et al., N.P. A828(2009)191
6.91
+/- 0.16
3D
------
Ex-----= 3.0
9
10
------ΛΛ Be ->Λ Be*
Theoretical calculations:
M.Danysz et al., PRL.11(1963)29;
R.H.Dalitz et al.,
Proc. R.S.Lond.A436(1989)1
3D
ΔBΛΛ
[MeV]
Recon.
at
Decay
23.3
+/- 0.7
14.7
+/- 0.4
3.77
+/- 1.71
0.6
+/- 0.8
1.3
+/- 0.4
# 4-body Cluster …A=7-10 DoubleΛ. Hiyama et al., PRC66 (2002) 024007
# 5-body Cluster Structure…11ΛΛBe. Hiyama et al., PRL104 (2010) 212502
11 / 46
n
Our knowledge on Ξ-N interaction
p
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.
1
2
・Attractive potential on Ξ Be 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, ~~~
n
E176 @ KEK-PS
K- interaction  Two ΛA were prod.
Λtwo step prod. can not be omitted.
p
12 / 46
Woods-Saxon well depth
of Xi-Nucleus potential
Ξ- stopping  Twin ΛA pair prod.
The first observations of clearly identified Ξbound systems.
BΞ− (MeV)
Ξ−+12C  4ΛH (#A) + 9ΛBe (#B) 0.54±0.20
4H* (#A) + 9 Be (#B) 0.35±0.20
Λ
Λ
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).
S. Aoki et al., Prog. Theor. Phys. 89, 493 (1993).
VΞ = V0Ξ (1+e(r-R)/a)-1
VΞ = V0Ξ (1+e(r-R)/a)-1
+ VLS + Ucoul(r)
V0Ξ = -(21~24) MeV
V0Ξ ~ -16 MeV by Ξ-12C
R = ro(A-1)1/3, a = 0.65 fm, ro = 1.1 fm
R = roA1/3, a = 0.65 fm, ro = 1.1 or 1.25 fm
Y. Yamamoto, Motoba, Fukuda, Takahashi & Ikeda
PTP., Suppl. 117, 281 (1994)
C. B. Dover and A. Gal, Ann. Phys. (N.Y.) 146, 309
(1994).
(1983).
13 / 46
Xi-Nucleus potential
n
p
#10-9-6 1) S. Aoki et al., Prog. Theor. Phys. 89, 493 (1993).
Λ
E176 @ KEK-PS
Two events : Twin ΛA pair prod.
Nijimegen Model D
 G-matrix interaction
#13-11-14 2) S. Aoki et al., Phys. Lett. B 355, 45 (1995).  VΞ = ∑
iexp(−( /i) )
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
S. Aoki et al., Nucl. Phys. A 828, (2009) 191.
吸収反応
生成核
Ξ− +12C=>
4 H + 9 Be
Λ
Λ
4 H* + 9 Be
Λ
Λ
4 H
Λ
Ξ− +14N=>
Ξ− +16O=>
+ 9ΛBe*
4 H* + 9 Be*
Λ
Λ
4 H + 1 1B
Λ
Λ
4 H* + 1 1B
Λ
Λ
4 H + 1 3C
Λ
Λ
4 H* + 1 3C
Λ
Λ
4 H + 1 3C*
Λ
Λ
4 H* + 1 3C*
Λ
Λ
4 H + 1 3C* a)
Λ
Λ
4 H* + 1 3C* b)
Λ
Λ
#13-11-14
#10-9-6
BΞ− (MeV)
BΞ− (MeV)
χ2
χ2
3.89 ± 0.14 1.3 ◎ 0.82 ± 0.17 0.4
2.84 ± 0.15
○ -0.23 ± 0.17
◎
0.82 ± 0.14
○ -0.19 ± 0.15
3.55 ± 0.15 3.5
2.50 ± 0.15
9.90 ± 0.18 11.2
8.85 ± 0.19
5.0 ± 0.2
3.9 ± 0.2
0.3 ± 0.4
-0.8 ± 0.4
0.79 ± 0.17 8.0
-0.26 ± 0.18
7.48 ± 0.21 19.5
6.43 ± 0.21
2.6 ± 0.2
1.5 ± 0.2
V0Ξ = -(16~17) MeV by Ξ-12C
Well reproduce 2p state : BΞ− = 0.58 MeV
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
Green Function
V0Ξ = -16 MeV by Ξ-12C
S.Tadokoro, H.Kobayashi and Y.Akaishi,
Nucl. Phys. A585, 225c (1995)
(1995).
14 / 46
Xi-Nucleus potential
n
Λ
p
E885 @ BNL-AGS
E224 @ KEK-PS
12C(Κ−,
12C(Κ−,
Κ+) int.
Κ+) int.
 Missing mass spectrum
 Missing mass spectrum
V0Ξ
by Ξ12Be
by Ξ12Be
-24 MeV
-20 MeV
-16 MeV
J. K. Ahn et al., Phys. Lett. B 378, 53 (1996).
V0Ξ > -20 MeV
T. Fukuda et al., PR. C 58, 1308
(1998).
・・・ reasonable agreement between the data
and theory is achieved by assuming a Ξnucleus potential well depth V0Ξ of about -14
MeV within the Woods-Saxon prescription.
P. Khaustov et al., PR. C 61, 054603
(2000).
16 / 46
Ξ-nuclei vs. H-nucleus
n
p
Λ
KISO event
Ξ−＋p
28.62
Ξ−＋14N (14361.912)
BΞ−=4.378 MeV
22.65
18.27
g.s.
(14339.265)
Λ＋Λ
If H nucleus was formed (M[H] - M [ΛΛ]
Ξ−＋p
18.6 MeV
28.62
H
10 MeV
Λ＋Λ
10
5
Λ He＋ Λ Be
10 MeV)
H nucleus
Ξ−＋14N
(14361.912)
22.65 seems to be BΞ− ~ 18 MeV
g.s.
~ 4 MeV
10
5
Λ He＋ Λ Be
(14339.265)
17 / 46
To get more informtion
n
p
Λ
@ J-PARC (coming soon)
・E07 … ~103 double-Λ hypernuclei
and ~102 Ξ-nucleus
・E03 & E07 … X-ray measurement
from Ξ atoms.
・E05 … High reso. spectr. of
Ξ hypernuclei.
18 / 46
n
p
３．The E07 experiment
and the KISO event
Λ
To obtain rich information about ΛΛ & ΞN interaction. !!
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,
kDepartment
of Physics, Toho University, Japan,
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.
lKEK,
JPN：９／KOR：３／MYM：２／CHN：２／USA：２／UK：１／IND：１
・・・・・・・・２０ Univ.・Inst.
19 / 46
n
p
Strategy of E07@J-PARC
Λ
1.New Hybrid method
2. Overall-scanning
Fully automatic detection of
3 vtx. event
like NAGARA event, KISO event
10 times statistics of that
with the hybrid method
(1/0.3): free from
acceptance & tracking
x
4 :･’
p’
(K-,K+)Ξ- in the emulsion
･’
n’
(K-,K0)Ξ- reaction
J-PARC
１．Pure K-beam
( better 3.5 times than KEK-PS)
２．More emulsion volume ( x 3 )
103 (E373)  104 Ξ- stop events
Measurement of the mass of
～103 double hypernuclei
～102 Xi hypernuclei
with A<16
１．X ray measurement from Ξ atom
with Hyperball-X
 study of Ξ-N interaction
2
２． ～10 double hypernuclei
Automated track-following
Development of
Λ E373 : alignment of plate by plate
[Grid Mark]
Accuracy :
~ 17+/- 9μm
/ 24.5×25 cm2
Detected
multi-candidates
~ 0.10mm
p
“Automated track-following”
~ 0.10mm
n
20 / 46
Automated track-following
Beam
#i
Upper face
Base
Down face
#(i+1)
Up
Base
Down
~ 90 s, Now
Alignment accuracy has achieved:
1.1 +/- 0.1 μm / 24.5×25 cm2
21 / 46
Development of
n
“Overall-scanning”
Λ
p
Primary motivation;
fast detection of α decay vertices
of natural isotopes to calibrate
range-energy relation.
① fast image capture
Developed system
with CCD camera
：Win2000 sp4
：3.0 GHz
1.57GB RAM
Camera ：100Hz (CCD)
Obj. lens：x 50
emulsion： 500μm
area
：0.1x0.08mm2
# of image：~100/cycle
Time
：5min. /cycle
 3sec/cycle
[~ hard limit]
OS
CPU
22 / 46
Development of
n
p
Λ
“Overall-scanning”
② fast image processing
α decay VTX
3 vertices
for event detection
Double-Λ
2 vertices (single-Λ cand.)
more
NAGARA event
was detected by this method
Until April. 2013,
8 M images under test operation (1.46 cm )
3
using E373 emulsion (55 liters)
23/ 46
n
p
An event by the “Overall-scanning”,
Λ
named“KISO”
Emitted back-to-back direction
 Topology seems to be consistent with the past events of twin hypernuclei (E176).
Results of KEK-E176: S.Aoki et al., NP. A828 (2009) 191-232
24 / 46
n
p
Λ
Image of the KISO event
25 / 46
Range-Energy relation
n
was
calibrated in good accuracy
p Λ for Std. emulsion
Proton
(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 weight
at 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
n
p
26 / 46
Outline of the KISO event
Λ
1) Ξ- hyperon can be produced in the target (8 mm from top the Em.)
E373 setup
2) Auger electron  make the capture point clear.
3) MIPS track from the decay point D.
4) TK #4  went out of the emulsion stack.
5) Consistent with Ξ- capture reaction
occurred on C, N or O.
#4
Vertices A & B
[1] The charge of #2 should be 2 or more.
[2] The charge of #1 should be ≦ 5.
[3] Hummer track : 8He, 8Li or 8B  8Be*(2+).
A
B
#4
n
Outline of the KISO event
27 / 46
Λ
p
Ranges and angles
vtx track range (µm) theta (deg.) phi (deg.)
#1
8.0 ± 0.3 133.0 ± 3.0 13.2 ± 3.2
A
#2
69.1 ± 0.5 40.4 ± 0.9 193.1 ± 1.2
#3
13.3 ± 0.4 102.3 ± 2.3 340.4 ± 1.6
B
#4
> 4990.7 145.0 ± 0.9 85.4 ± 1.3
#5
6.7 ± 0.3 49.6 ± 4.2 132.6 ± 4.3
D
#6
5.8 ± 0.3 131.0 ± 4.5 318.9 ± 4.7
#7 2492.0 ± 3.9 43.1 ± 1.3 191.8 ± 1.5
C
#8
37.3 ± 0.7 131.9 ± 1.3 29.2 ± 1.3
comments
Single-hypernucleus
77.1 ± 0.3 µm : B ~ C
Out of the emulsion stack
8
α from Be
8
α from Be
28 / 46
n
Vertex
p Λ D
Analysis of the KISO event
0
5
10 (μm)
(a)
(b)
8Be*(2+)
D
0
5
Vertex B
Mass of 8Be∗(2+)
(MeV/c2 )
7457.890
(Γ = 1.5 MeV)
Reconstructed mass
(MeV/c2)
7458.531 ± 0.307  Using measured data
7458.540 ± 0.308  Under the momentum balance
→ 2α at VTX. D
10 (μm)
Possibility of mesonic decay of #1  denied !!
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 understand
the decay mode with a π0 meson at the decay point of #1.
B
#4
Non-mesonic decay at VTX. B
8B
: charge conservation at VTX#A
: mom. imbalance at VTX#A
8He
Vertex B
n
p
Possible process at VTX. B
29 / 46
Λ
B
#4
Mc : Mass of a core nucleus + M(Λ)
Mr : reconstructed minimum mass
Mc - Mr : BΛmax. should be plus value.
There is no bound hyperfragment for track #2
The particle (#1) can be 1Λ0Be or 1Λ1Be.
Vertex A
n
p
30 / 46
Possible process at VTX. A
Λ
A
The mode :
Ξ− + 14N  1Λ0Be + 5ΛHe
was uniquely identified
31 / 46
n
＊Event interpretation and the energy of BΞ-
p
Λ
Process of the KISO event
Ξ− + 14N  1Λ0Be (#1) + 5ΛHe (#2),
10Be  8Li (#3) + p (#4) + n,
Λ
− )
8Li  8Be*(2+) + e- (+ ν
e
8Be*(2+)  2α (#5 & # 6)
5 He
Λ
ex.
 p(#7) + d(#8) + 2n
BΞ− = 4.38 +/- 0.25 MeV (by Mom. balance [#1 and #2])
Measurement error : 0.09 MeV
Mass (1Λ0Be, 5ΛHe, Ξ−) error : 0.23 MeV
32 / 46
n
p
The case of production of
10Be in excited state
Λ
Λ
BΞ− = M(Ξ−+14N) – E(1Λ0Be) – E(5ΛHe)
[28] E. Hiyama and Y. Yamamoto, PTP 128, 105 (2012)
[29] D. J. Millener, Nucl. Phys. A 881, 298 (2012)
33 / 46
the KISO event
Ξ− + 14N  1Λ0Be + 5ΛHe uniquely identified!!
BΞ− = 4.38 +/- 0.25 MeV (by Mom. balance for 1Λ0Be and 5ΛHe)
p Λ
3.7σerr far from 3D level
9Be
system
6.509 (4-)
6.433 (3-)
5
BΞ− = 0
(1+)
(0+)
3.27
3.07
2.41 (3--)
2.36 (22)
-
0.08 (21)
3.228 (1-)
3.202 (0-)
2.585 (3--)
2.482 (2 )
-
0.110 (2 )
BΛ = 9.11 +- 0.22(exp.)
The first evidence of a
10Be
Λ
g.s.
Ξ-14N
1.11±0.25
1.14
2
3
4
4.38±0.25
5
Err.(meas.)=±0.09
Err.(mass)=±0.23
5.69
Λ
3D
2p
system to be bound deeply. 1s
34 / 46
Comarison of E176 events
with theoretical prediction
n
p
PTP. 105 (2001) 627
1
10
H & Y DJM
Ξ−14N
0.174
BΞ− (MeV)
Energy (MeV)
0
+Λ 0
(σerr ~ 0.25 MeV)
The paper well presented that
the past two event to be occurred
in 2p nuclear bound state.
Theoretical predictions
Yamaguchi, Yamamoto & Ueda
n
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)
E176 results; S.Aoki et al., NP. A828 (2009) 191-232
Ξ− binding energy (MeV) in nucleus : 12C [most probable]
Good agreement
with
a theoretical prediction
in the case of
Ξ− - 12C system
Published at
K. Nakazawa et al.,
Prog. Theor. Exp. Phys. 2015, 033D02
DOI : 10.1093/ptep/ptv008
New scanning system
for the E07emulsion
n
p
35 / 46
Introduced by Dr. J. Yoshida Jul.11th
Λ
×300
faster !!
with piezo stage
Present
110 μm
Present system
130 μm
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
4 sets
3 sets
200 μm
1140 μm
Images of all of the emulsion can be obtained in a few years.
Outline of the E03 experiment
36 / 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
Ξ−
Fe target
(dss)
K-
K+
Ξ−
Fe
X ray
X ray
Energy (arbitrary scale)
37 / 46
Ξ atom level scheme
...
l=n-1 (circular state)
l=n-2
l=n-3
Ξ
...
Z
nuclear absorption
...
...
Ξ
Z
l (orbital angular momentum)
X ray energy shift – real part
Width, yield – imaginary part
38/ 46
E03 detectors
TOF
Hyperball-J
CH
K+
K-
DC3
Ξ-
BAC
FBH
BH2
KURAMA
PVAC
FAC
DC1
DC2
Acceptance & Efficiencies
39 / 46
• 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
Hyperball-J in E13
• Worked well
• Livetime: ~80%
with K+π: ~500 k/spill
• Resolution: 3-4 keV@197 keV
E13 CF4 run
17F
(197keV)
40 / 46
41 / 46
n
p
Λ
42 / 46
n
p
Λ
43 / 46
n
p
Λ
44 / 46
n
p
Λ
45 / 46
n
p
Λ
46 / 46
n
4. Summary
p
1.
ΛWe have performed experiments to study S=-2 systems with the nuclear
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  1Λ0Be + 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 Coulombassisted 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.
emulsion at KEK. However, very little is known, so far.