ハイパー核分光ハイパ 核分光ーKEK‐PSからJ‐PARCへー
2008.12.5 金茶会2008.12.5 金茶会
高橋俊行
ContentsContents
• Introduction• Λ hypernuclei
– Production reactions– Spectroscopy & ΛN Interaction
• Reaction SpectroscopyReaction Spectroscopy• γ‐ray Spectroscopy
– Baryon in Nuclei• KEK‐E419/J‐PARC E13
• S=−2 systemM ti ti– Motivation
– ΛΛ hypernuclei – Ξ hypernuclei & J‐PARC E05Ξ hypernuclei & J PARC E05
Baryon Octet (バリオン八重項)Baryon Octet (バリオン八重項)
陽 中性 仲間陽子・中性子の仲間
• S=0– p, n I=1/2
• S=−1S 1– Λ I=0– Σ (Σ+ Σ0 Σ−) I=1Σ (Σ ,Σ ,Σ ) I=1
• S=−2Ξ (Ξ0 Ξ−) I 1/2– Ξ (Ξ0,Ξ−) I=1/2
これらを含む原子核を
ハイパー核という
Λ ハイパー核ーもっとも軽いハイパー核-
寿命: Λの寿命(260ps)程度τ=200ps =Γ
chτ=200ps原子核の半径: r=3.5fm (A~20)光速で回転するとして、崩壊までに
* /(2* * )fmMeV 200 ⋅
=
Γτc
n=c*τ/(2*π*r) =3x108x2x10‐10/(2x3.14x3.5x10‐15)=2.8x1012
fm10102103 15108 − ××⋅×
回まわる MeV103.3 12−×=
Baryon多体系(原子核)を充分な時間形成し、状態の幅も充分狭い状態の幅も充分狭い。
3次元核図表3次元核図表
• S=0 (通常原子核)S 0 (通常原子核)– 安定核種 ~300– 確認 ~3000
存在 6000– 存在 ~6000• S=−1
– Λハイパー核 35– ∑ハイパー核 1
• S=−2ダブルΛ イパ 核– ダブルΛハイパー核
3(5)
Discovery of Hypernulei in 1952Discovery of Hypernulei in 1952Marian Danysz & Jerzy Pniewski
Phil. Mag. 44 (1953) 348
Track Range G.D. Identity EnergyFragement f Charge 5
1 9 μm Black p, d, t, or α 0.7 MeV (p)
2 123 μm Black p, d, t, or α 16 MeV (α)
3 3 7±0 2 d t 82 M V ( )
gRange 90μmEnergy ~60MeVTime of Flight 3ps
3 - 3.7±0.2 p, d, t, or π 82 MeV (p)
4 2 μm Black Recoil -Released Energy at B
~140MeV
ハイパー核物理の特長ー研究の目的ー
イペ は 排他律を受けな• ハイペロンは、Pauli排他律を受けない– 原子核深部を探るプローブ
• Impurity Physics– Grue‐like role– 核構造の変化– 媒質中のhadronの性質媒質中 性質
• Baryon‐Baryon Interaction– YN YY Interaction based on SU(3)fYN, YY Interaction based on SU(3)f– 核力の統一的理解
Reactions to Produce Λ HypernucleiReactions to Produce Λ Hypernuclei• In‐flight (K−,π−), (K−,π0) Reaction
– Recoilless production PK=~0.5GeV/c– Substitutional states
• (π+,K+) Reaction– Large mometum transfer ~400MeV/c > kFLarge mometum transfer 400MeV/c > kF– Spin‐streched states
• Stopped (K− π−) Reaction• Stopped (K ,π ) Reaction– Large production ratesNo special selectivity– No special selectivity
• (γ,K+), (e,e’K+) Reaction– Large momentum transfer sim. (π,K)– Both spin‐flip and spin‐non‐flip states
Transfered momentum for elementary reactions
+ →K+Λ
γp →K+Λ
V/c]
π+n →K+Λ
tum [M
eV
K−n → π−Λ
il mom
ent
10°0°
Recoi
Beam momentum [GeV/c]
K−n→ π+Λ Cross SectionK n→ π+Λ Cross Section• PK~0.8GeV/cで最大
– q~50MeV/c 1.6GeV/cでも大きいPK>1.6GeV/cでも大きい– Recoillessではない。
• q > 100 MeV/c
– Spin non‐flip
Cross Section for (π K) ReactionsCross Section for (π,K) Reactions
• 1.05GeV/c π+ beamfor Λ productionπ+n−>K+Λ
• Spin non‐flip amplitude
π+p−>K+Σ+
π+n−>K+Σ0
π−p−>K+Σ−
各反応でのスペクトル(理論予想)12Cを標的としてー 12Cを標的としてー
(K−,π−) reaction• Substitutional state: 0+• Large production cross section ~mb/sr
(π+ K+) reaction(π ,K ) reaction• Bound states• Spin stretched states: 2+• Small production cross section ~10μb/srSmall production cross section 10μb/sr
(e,e’K+) reaction( , )• Bound states• Unnatural parity states (2−,3+) as well as natural parity states
• Very small production cross section ~10nb/sr
反応分光測定装置ー SKS & K6 beamline @KEK ー
K+
ビームπ+, 散乱K+の運動量と散乱角(粒子の飛跡)を事象ごとに測定し、Missing Massを求める。
チェレンコフ検出器粒子の識別 K g
P ~0 7G V/
粒子の識別
+
P=~0.7GeV/c
Drift Chamber粒子の飛跡を測定
π+
P 1 05G V/P=1.05GeV/cSKS
B=2.2T (max. 3T)Gap 50 cm
Plastic Sintillator飛行時間の測定
Gap 50 cmΔΩ = 100 msr
12 C Spectrum Measured with SKS12ΛC Spectrum Measured with SKS
11C Λ ( t t )11C + Λ (s‐state)
11C + Λ (p‐state)
11C* + Λ (s‐state)
Core核の励起状態にs‐stateのΛが結合した状態
SKSで初めて観測
hi l ( )H.Hotchi et. al, PRC64(2001)044302
Λハイパー核分光データからわかることー Single Particle Orbit of Λ ー
H.Hotchi et. al, PRC64(2001)044302
ポテンシャル中のΛの1粒子状態
Pauli排他律が働かない。Pauli排他律が働かない。Λは核子とは別粒子
Single Particle Energy of Λand Λ‐Nucleus Potential
Woods‐Saxon Potential
)(12
⎟⎞
⎜⎛ rdf rh51
1)(
)(1)()( 0
=
⎟⎟⎠
⎞⎜⎜⎝
⎛+= ΛΛΛ
rf
sldr
rdfrcm
VrfVrU LSrrh
π
51ΛV
12ΛC
M V31)1(
,))(exp(1
)(
3/10 −=
−+=
ΛVARR
aRrrf
fm840fm 1.1MeV31
with 00
==−=Λ
aR
V208
ΛPb139
ΛLa89
ΛY28ΛSi fm84.0=a
陽子や中性子では、−50MeV
ΛN相互作用は NN相互作用よりも弱い
Λ
E140a, T.Hasegawa et. al, ΛN相互作用は、NN相互作用よりも弱いE140a, T.Hasegawa et. al,PRC53(1996)1210
Spin Orbit PotentialSpin‐Orbit PotentialNormal Nuclei (S=0)では、重要( ) 、 要
Shell model by Mayer & Jensen
slrvV SOrr
⋅= )(
j = l±1/2でレベルが分離する
)12()(21
+>
Spin‐Orbit Potential of Λー 13ΛC* からのγ線測定 ー
BNL AGS E929BNL AGS‐E929H.Kohri et. al, PRC 65(2002) 034607A.Ajimura et. al, PRL 88(2001) 4255
13C (K−,π−) 反応で 13ΛC*を生成48D48 Spectrometer
13ΛC* からのγ線を測定
NaI Detector12C
13ΛC
Λがp1/2Λがp3/2LS partnerLS partner
K−
π−
Spin‐Orbit Potential of Λー 13ΛC* からのγ線測定 ー
厚い標的かつスペクトロメータの分解能が悪いので厚 標的か クト タの分解能が悪 のでMissing Massではピーク構造は見えない。
BΛ(G.S)=11.69±0.12MeV (Emulsion)
γ線スペクトル
薄い標的でのスペクトル
unbound region
bound regionbound region
Spin‐Orbit Potential of Λー 13ΛC* からのγ線測定 ー
2つの kは分離できないが 1/2 ( )と3/2+( )の生成の角度分布2つのpeakは分離できないが、1/2− (p1/2)と3/2+(p3/2)の生成の角度分布が違うことを使って、2つの状態のエネルギー差を求める。
E(1/2−)=10.982±0.031±0.056 MeVE(3/2−)=10.830±0.031±0.056 MeV
ΔE=152±54 keV
Λの場合、Spin‐orbit Potentialは非常に小さい非常に小さい。核子の場合は、p‐orbitで約6MeV
Hypernuclear γ‐ray Spectroscopy and ΛN Interaction
• Small spin‐dependent ΛN interaction – Spin‐orbit splitting of 13ΛC ~150keVp p g Λ
E i t l l ti• Experimental resolution– (π+,K+), (K−,π−) with Mag. Spec. 2‐3MeV– γ‐rays with NaI 350keV@10MeV– (e e’K+)
Hypernuclear Fine Structureand ΛN (Effective) Interaction
ΛN ( ff ti ) i t tiCore Nuclei (p‐shell) + Λ in s‐state ΛN (effective) interaction
Λ
⋅+=
rrN
ssrVrVrV
)()()( 0 Central
Spin‐spin
Λ
ΛΛΛ
Λ
⋅+
⋅+
⋅+ σ
rr
rr
NNN
N
N
slrV
slrV
ssrV
)(
)(
)( p pΛ spin‐orbit
N spin‐orbit
ΛΛ
Λ
⋅−⋅⋅=++
σσσσ rrrrrr NNT
NNN
rrSSrV
slrV
))((3)()(
12
12Tensor
Radial integral by Λ in s‐state and N in p‐state W.F.p‐shell Λ hypernuclei
TSS N ,,, , V ΛΔp shell Λ hypernuclei
pA‐5N sΛ
HyperballHyperball
• 14 Sets of Ge & BGOff– Ge: 60% rerative efficiency
– BGO: 6 seg. per each
• Solid angle coverage: 15%• Solid angle coverage: 15%• Photo‐peak efficiency
– 2 5%@ 1MeV– 2.5% @ 1MeV
• KEK E419, E509/ BNL E930• Transistor reset & gated• Transistor reset & gated
integrator amplifier
Hyperball2Hyperball2
• Hyperball +6 sets of Clover type Ge detetors6 sets of Clover‐type Ge detetors
• 25% solid angle coverage• Photo peak efficiency• Photo‐peak efficiency
– 4% @ 1.33MeV
• KEK E518/E566• KEK E518/E566
7 Liー Spin spin Interactionー7ΛLi ー Spin‐spin Interaction ーKEK E419 (1998) (π+,K+) spectrum measured by SKS
H.Tamura et. al, PRL84(2000)5963PRL84(2000)5963
E(3/2)−E(1/2) = 1.444Δ +0.054SΛ +0.016SN −0.271T
Thin target data by E336
7ΛLiー Spin‐spin InteractionーΛLi Spin spin Interaction
γ ray spectra
unbound region
bound region w/o Doppler Corr.
bound region w/ Doppler Corrbound region w/ Doppler Corr.
E(3/2−>1/2)=692keV Δ = 0.43 MeV
9ΛBeー Λ spin‐orbit InteractionーΛBe Λ spin orbit Interaction
BNL E930(‘98) H.Akikawa et. al, PRL88(2002)082501H.Tamura, NPA754(2005)58c
9ΛBe: α‐α‐Λ cluster
E(3/2+ −> 1/2+) = 3067 ±3 ±1keV(3/ / ) 306 3 eE(5/2+ −> 1/2+) = 3024 ±3 ±1keV
E(3/2+)−E(5/2+) = 43 ±5 keV
E(3/2+)−E(5/2+) = −0.037Δ −2.464SΛ +0.003SN +0.994T +ΛΣ
SΛ = −0.01 MeV
16ΛO ー Tensor InteractionーΛO Tensor Interaction
BNL E930(‘01) 16O(K−,π−γ)M.Ukai et. al,PRL93(2004)232501
Λ
E(1−)−E(0−) = −0.382Δ +1.378SΛ −0.004SN +7.850T +ΛΣ
E(1− −>1−) = 6534.3±1.2±1.7 keVE(1 0 ) 6560 4±1 1±1 7k VE(1− −>0−) = 6560.4±1.1±1.7keV
E(1−) – E(0−) = 26.1±1.4±0.6keV
T=0 03 MeVT=0.03 MeV
7ΛLi: Completely known levels
ー N Spin‐orbit Interaction ーBNL E930(‘01) M.Ukai et. al,
10B(K−,π−)10ΛB*7
ΛLi* + 3He
Single‐γ spectrum
,PRC73(2006)012501(R)
γ γ consident spectrumγ−γ consident spectrum
E(7/2+−>5/2+) = 470.8±1.9±0.6 keV
E(7/2+,5/2+) –E(3/2+,1/2+) = E(6Li;3+)–E(6Li;1+)−0.05Δ +0.07SΛ +0.70SN −0.08T
S 0 43 M VSN = −0.43 MeV
Identified γ‐rays from p‐shell h lhypernuceli
inconsistent
Obtained parameters & YN Interaction Models
• Spin‐spin Δ=0.43MeV– NSC97e, NSC97fの中間(spin‐spin力を調整した)
• Spin‐orbit SΛ=−0.01MeV, SN=−0.43MeV– Nijmegen Model (meson‐exchange model)j g ( g )
• −0.18
Inconsistency y
0.578 Δ + 1.41 SΛ + 0.014 SN ‐1.07 T + ΛΣ10ΛB2−
Λ NΛB195keV −15keV
Experimentally not observed !
Shrinkage of 7ΛLiー Grue like role of Λ ー
E Hi t l6Li 7ΛLi
pnrn‐p
nrn‐p
E.Hiyama et. al,PRC59(1999)2351
417 )2/15/2B(E2;Li)( ⎤⎡ → ++R
α
p
Rcore‐(n‐p) αp
Rcore‐(n‐p)Λ
5ΛHe
6 )13 B(E2;)2/15/2 B(E2;
Li)(Li)(
⎥⎦
⎤⎢⎣
⎡→→
= ++−
Λ−
d
dc
RR
α
ΛHe
B(E2): transition probabilitytransition probability
~1/ττ: lifetime
Rcore‐(n‐p)
Measurement of lifetimeー Doppler Shift Attenuation Method ー
生成したハイパー核は反跳運動量を持つ。 t
J PARC E13J‐PARC E13
• Hypernuclear γ‐ray spectroscopy via (K−,π−γ)– PK=1.5GeV/c with SksMinus & Hyperball‐JK / yp
• Targets and purposes4 H CSB f 4 H– 4ΛHe CSB c.f. 4ΛH
– 7ΛLi B(M1) & gΛ in meaduim– 10,11ΛB ΛΣ coupling ...– 19ΛF sd‐shell hypernucleusΛF sd shell hypernucleus
77ΛΛLi: B(M1) measurement and Li: B(M1) measurement and ΛΛ in nucleusin nucleus
1+ 3/2+
J=1 J+1/2 Nuclear medium effectNuclear medium effect
6 Li
1+ 3/2
1/2+M1692keVT=0, L=0,S=1 •No Pauli blocking
→Λ in 0s orbit63Li 7
ΛLi/
J-1/2
1
→Λ in 0s orbit•Partial restoration of chiral symmetry?
)1(1 3 MBEγτ∝=Γ
Doppler Shift Attenuation
reduction of constituent quark massMethod
In the weak coupling limit between Λ and the core nucleus
mass→ change of μΛ
[ ] CNJJ
ggJJMB −∝==∝ Λμμ222 )(2/12/3)1(
CC JgJg += ΛΛμ gΛ,gc: Effective ffective g factor of Λ and core nucleus, respectivelyJΛ, Jc: Total spin of Λ and core nucleus, respectively
B(M1) measurementDifficulties in B(M1) measurement
Doppler Shift Attenuation Method works only when τ < tstop τ is very sensitive to Eγ because B(M1) ∝ 1/τ ∝Eγ3. But Eγ is unknown.Cross sections and background cannot be accurately estimated.
~
To avoid ambiguities, we use the best-known hypernucleus, 7ΛLi.Energies of all the bound states and B(E2) were measured
Cross sections and background cannot be accurately estimated.Previous attempts: 10ΛB , 11ΛB (Eγ too small −> τ >> tstop ), 7ΛLi (byproduct: indirect population)
Energies of all the bound states and B(E2) were measured,γ-ray background level was measured, cross sections are reliably calculated.
τ = 0.5ps, tstop = 2-3 ps for 1.5 GeV/c (K-,π-) and Li2O target Calc. by Motobap y
(K-,π-)
PRL 84 (2000) 5963PRC 73 (2006) 012501
S=−2 SystemS= 2 System
H i l• H particle• ΛΛ hypernucleusyp• Ξ hypernucleus• Baryon‐Baryon Interaction in S=−2– ΛΛ
ΞN– ΞN– ΞN −> ΛΛ– H particle ?
S=−2 Systemー Dynamical System ー
ll d ff• small mass difference between ΛΛ and ΞN
~ 28 MeV
– ΞN‐ΛΛ Mixing– Three‐body force via the
ΞN‐ΛΛ interaction
Λ ΛN
L i i ff d h b d f
Ξ
Large mixing effect and three‐body forceare expected in S=−2 system.Λ Λ N
Studies of S= 2 System at J PARCStudies of S=−2 System at J‐PARC• E03: Measurement of X rays from Ξ− atomsy
– atomic level shift• Ξ‐A Potential (surface)
• E05: Spectroscopy study of Ξ‐hypernucleus, 12ΞBe, via the 12C(K−,K+) reaction– Ξ‐A Potential ( interior)– ΞN, ΞN−>ΛΛ interaction
• E07: Systematic study of double strangeness systems with an emulsion‐counter hybrid method– double‐Λ hypernuclei ‐ ΛΛ interaction– twin‐Λ ‐ Ξ Potential (interior)– X‐rays from Ξ‐atom ‐ Ξ Potential (surface)
Production & Measurement of S=−2 System
p + K− > Ξ− + K+p + K −> Ξ + K+
Quasifree Ξ Production~1.8 GeV/c
Direct productionReaction Spectroscopy
Ξ Hypernuclei
Double Λ Compound StatesΞ− Atom
X‐rays measurements
Double Λ Fragment
Decay measurementsDecay measurementsEmulsion
Nagara Event & ΛΛ InteractionNagara Event & ΛΛ Interaction
A:H.Takahashi et. al, PRL87(2001)212502KEK E373
A:12C + Ξ− −> 6ΛΛHe + 4He + 3H
H.Takahashi et. al, PRL87(2001)212502
B:6
ΛΛHe −> 5ΛHe + p + π−
BΛΛ = 7.25±0.19 MeVΔBΛΛ = 1.01±0.20 MeV
+0.18−0.11+0.18−0.11
assuming BΞ− = 0.13 MeV
(3D state)
0.
( )Weakly attractive ΛΛ Interaction
MH ≧ 2223.7 MeV
Ξ Potential & High Density Nuclear Matter
Λ Σ Ξ K i h f N S
μ B = m B +kF
2
2m B+ U (k F )
Λ, Σ−, Ξ−, K− in the core of Neutron‐Star
m B
depends on Mass, Charge, and PotentialUΣ 0
Baryon‐Baryon Interaction ModelUΞ and Partial Wave Contributions in Nuclear Matter
(MeV)
Model T 1S0 3S1 1P1 3P0 3P1 3P2 UΞ ΓΞ
NHC-D 0 −2.6 0.1 −2.1 −0.2 −0.7 −1.91 −3.2 −2.3 −3.0 −0.0 −3.1 −6.3 −25.2 0.9
Ehime 01
−0.91 3
−0.58 6
−1.00 8
0.30 4
−2.41 7
−0.74 2 22 3 0 51 −1.3 −8.6 −0.8 −0.4 −1.7 −4.2 −22.3 0.5
ESC04d* 01
6.37 2
−18.4−1 7
1.2−0 8
1.5−0 5
−1.3−1 2
−1.9−2 8 −12 1 12 7
• OBE (NHC‐D, Ehime)odd state attraction
1 7.2 1.7 0.8 0.5 1.2 2.8 12.1 12.7
• ESC04d*strong attraction of 3S (T=0)– odd‐state attraction
– strong A‐dependence of VΞ– Narrow width
– strong attraction of 3S1(T=0)– Large width
Narrow width
12C(K−,K+) Missing Mass SpectroscopyC( , ) ss g ass Spect oscopy
PKh t t l
BNL AGS E885KEK E224 T.Fukuda et. al,PRC58(1998)1306 P.Khaustov et. al,
PRC61(2000)054603
ΔM=10MeV(FWHM)
PRC58(1998)1306
ΔM=13MeV(FWHM)
ΔM=10MeV(FWHM)for H(K−,K+)Ξ−
VΞ = −14 MeV ?
W.S. Potential Calc.with Γ=1MeV
E05: Spectroscopic Study of Ξ‐Hypernucleus, 12
ΞBe, via the 12C(K−,K+) Reaction
• Missing mass spectroscopy via the (K−,K+) reaction– K1.8 Beam Analyzer 1.8GeV/c K−
• Δp/p = 3.3x10−4
– SksPlus Spectrometer ~1 3GeV/c K+– SksPlus Spectrometer 1.3GeV/c K• 30msr• Δp/p = 0.17%
20 – ΔM=3MeV(FWHM)
• The first observation of
VΞ = −20 MeVp Ξ
Ξ hypernuclear states– Ξ‐Nucleus Potential– Ξ‐N Interaction
s Ξ– Ξ‐N Interaction– Ξ‐N −> ΛΛ Conversion VΞ = −14 MeV
RCSRCS
ννMLF
HDHDBird’s eye photo in Feb. 20082008/10/27 48特定領域研究会2008
Hadron Hall 2008 Dec 3Hadron Hall 2008 Dec. 3
K1 8 Beamline at Hadron HallK1.8 Beamline at Hadron Hall
ES2
K1.8 beamline Phase‐II (750kW) Phase‐I (270kW)
ES1
Length [m] 45.853
Acceptance [msr %] 1.4
K‐ intensity (FF) @1.8GeV/c 6.6x106 1.4x106y ( ) @ /@1.5GeV/[email protected]/c [ppp]
2.7x106
3.8x1055.4x105
8.0x104
K‐/(p‐+m‐) @1.8GeV/c 4.0 3.5
SKS MagnetSKS Magnet北CHでの解体 ・コイル容器取り出し(2008.1) J‐PARCハドロンホール
への輸送 (2008 9)への輸送 (2008.9)
残りヨーク解体 (2008.9) コイル容器改造終了@東芝京浜工場(2008 10)@東芝京浜工場(2008.10)
2008/10/27 51 特定領域研究会2008
まとめ ーハイパー核の物理ーまとめ ーハイパー核の物理ー
排他律を受 な 粒 注• Pauli排他律を受けない粒子の注入– 原子核構造の変化原子核構造 変化– ハドロン(ハイペロン)の性質の変化 を探るバリオン間相互作用• バリオン間相互作用– SU(3)fに拡張して、核力を理解する。
• S=−2のハドロン多体系J PARCで本格的に開始– J‐PARCで本格的に開始
– multi‐strangeness系(高密度、、)への第1歩
backup
44ΛΛHe: He: Spin dependent Charge symmetry breaking Spin dependent Charge symmetry breaking
(CSB) in (CSB) in ΛΛN interactionN interaction• Lightest mirror hypernuclei → ΔBΛdirect measure of ΔEcsb,ΛN :
ΔBΛ≈ ΔEcsb,ΛN
( )( )
keVHBHeBB 70)()( 44 ±=−=Δ ΛΛΛΛ 350
• CSB effect in NN interaction calculated from 3H and 3He ΔEcsb ΝN
keVHEHeEE 160)1;()1;(
)()(44 ±=−=Δ +Λ
+ΛΛ
ΛΛΛΛ
270
CSB effect in NN interaction calculated from H and He ΔEcsb,ΝN≈ 80keV (Faddeeve calculations, Y.Wu et. al., PRL 64 1875 (1990))
A few times larger CSB effect in A few times larger CSB effect in ΛΛN than in NN ??N than in NN ??
(K-,π- )
Re measure withRe‐measure with 0.5% accuracy
4ΛHe and CSB
Observed CSB looks spin-independent.
??ΛN-ΣN coupling gives spin-dependent CSB.
??
Very large CSB !?
stop K- on 6Li by NaI (1979)
Liq. 4He 25cm (1.25 g/cm2)10 hours
Very large CSB !?Not theoretically understood.
stop K- on 6Li by NaI (1979)4
ΛHe: Only one dataBad quality
4ΛH* : (e,e’K+) at Jlab
(K-,π0γ) at J-PARC
1010ΛΛB: the puzzleB: the puzzle
Shell model prediction10B (K‐,π‐ γ) 10ΛB 0.8~0.93GeV/c(BNL E930)
Experimentally not observedExperimentally not observed3/2-
2-0.578 Δ + 1.41 SΛ + 0.014 SN ‐1.07 T + ΛΣ
195keV ‐15keV
(BNL‐E930)
EEγγ Experimentally not observed:Experimentally not observed:(1)Eγ below experimental sensitivity
→ E ‐15keVThree‐body force by ΛΣ coupling• better wave function for 9B
(2) 2‐ (non spin‐flip) and 1‐ (spin‐flip) reversed in energy
p g‐‐ Not well known
reversed in energy• pk= 0.8~0.93GeV/c (BNL E930)
→ non spin‐flip population→ non spin flip population• pk = 1.8GeV/c (E13 J‐PARC)
→ spin flip/non spin flip
Expected yield and sensitivityExpected yield and sensitivityYield estimate
NK = 0.5 x 106 /spillTarget (7Li in Li2O) = 20cm x 2.0g/cm3 x 14/30 x 0.934 / 7 x 6.02x1023
∫dσ/dΩ(1/2;1) ΔΩ x BR(1/2+;1->3/2+) = 0.84 μb x 0.5ε(Ge) x ε (tracking) = 0.7 x 0.6 => Yield (3/2+->1/2+) = 7.3 /hr(1000 spill)
= 3600 / 500 hrsBackground estimated from E419 7ΛLi spectrum
Stat. error Δτ/τ = 5.4%Δ|g -g |
Fitting result: 0.478±0.027 psSyst error < 5%
Δ|gΛ-gc||gΛ-gc|
~ 3%=>
Syst. error < 5%mainly from stopping time
H ParticleH Particle
• predicted by R.L.Jaffe in 1977– uuddss
Phys. Rev. Lett. 38 (1977) 195
– JPC = 0++
– M = 2150 MeV/c2 by MIT bag model• Color‐magnetic interaction
/⋅⋅−=Δ ∑ mm jijiji λλσσαrrrr N: # of constituent quarks
Δ 24 for H
)1(34
218/ 6 ++−=⋅⋅∑
<
<
JJCNmmji
jijiji
ji
λλσσrrrr C6: SU(6)flavor‐spin Casimir operator
– Δ=−24α for H• ΣΣ−Ξ+ΛΛ=
83
84
81 NH
888
Mass of H and ΛΛ hypernucleusMass of H and ΛΛ hypernucleus
If MH > 2MΛ, H decays to ΛΛ viastrong interaction.MH 2 MΛ – BΛΛ.
Z)(2BZ)(B Z)(B)ZM()M(2)ZM(Z)(B
1AAΛΛ
A
A2AAΛΛΛΛ
−ΛΛΛΛΛΛΛΛ
ΛΛ−
−=Δ−Λ+=
ΛΛ Interaction Energy
ΛΛ Nucleus Events (1)ー Emulsionー
D.J.Prowse, PRL17(1966)782M.Danysz et. al, NP49(1963)121
10ΛΛBeor
ΔBΛΛ=4.5±0.4 MeV
6ΛΛHe ? ΔBΛΛ=4.7±1.0 MeV
11ΛΛBe ΔBΛΛ=3.2±0.6 MeV
ΛΛ Nucleus Events (2)ー Couter‐Emulsion Hybrid Method ー
S.Aoki, et. al, KEK PS E373Prog. Theor. Phys. 85 (1991)1287
KEK PS‐E176
KEK PS‐E373
Demachiyanagi‐Event
Ξ 12C 10 B (*) tΞ− + 12C −> 10ΛΛBe(*) + tBΛΛ = 12.3±0.2 MeVΔBΛΛ = −1.1±0.2 MeV(g.s.)
0 3
+0.3−0.1+0.3−0.1
side‐view
ΔBΛΛ = 1.9±0.2 MeV(e.s.)+0.3−0.1
3‐body case3‐body caseΔBΛΛ > 1.5 MeV
+2.4−0.7
10ΛΛBeor
ΔBΛΛ = ‐4.9±0.7 MeVor
13ΛΛB ΔBΛΛ = 4.9±0.7 MeV
Counter‐Emulsion Hybrid Methodー KEK PS E373 ー
• Identify Ξ− production via the (K−,K+) by spectrometer• Measure the track of Ξ− by SciFi‐Bundle detector • Search for Ξ− absorption point (and its decay) in the emulsion• Search for Ξ absorption point (and its decay) in the emulsion
Twin Λ Hypernuclei EventsTwin Λ Hypernuclei EventsSecond Event in E373
Ξの吸収点から2つのΛハイパー核が生成
Ξの束縛エネルギーを求める
Twin Λ Hypernuclei EventsTwin Λ Hypernuclei Events• E176 Yokohama Event • E373 First Event PLB500(2001)37
– Ξ−+12C−>4ΛH+9ΛBe BΞ=0.54±0.20 MeV– Ξ−+14N−>4ΛH+11ΛB BΞ=0.35±0.20 MeV– Ξ−+16O−>4 H+13 C B =6 62 MeV
– Ξ−+14N−>5ΛHe+5ΛHe+4He+nBΞ=−2.6±1.2 MeVconsistent with the capture +0.23
Prog. Ther. Phys. 89(1993)493
– Ξ + O−> ΛH+ ΛC BΞ=6.62 MeV
• E176 Korea Event– Ξ−+12C−>4ΛH+9ΛBe BΞ=3.70 MeV
12 4 9
from the atomic oribit
• E373 Second Event– Ξ−+12C−>7ΛLi(*)+6ΛH
+0.18
‐0.22
‐0.190 18
PLB355(1995)45
– Ξ−+12C−>4ΛH+9ΛBe* BΞ=0.62 MeV– Ξ−+12C−>4ΛH*+9ΛBe BΞ=2.66 MeV
• E176 Kariya Event
Ξ + C > ΛLi( )+ ΛH BΞ=1.6±0.3 MeV (g.s.)
BΞ=0.9±0.3 MeV (e.s.)– Ξ−+12C−>7 Li(*)+5 He+n
+0.18
+0.18‐0.19
‐0.19
Ξ + C > ΛLi( )+ ΛHe+nBΞ=1.1±0.4 MeV (g.s.)
BΞ=0.4±0.4 MeV (e.s.)Ξ−+14N >9 Be(*)+5 He+n– Ξ +14N−>9ΛBe( )+5ΛHe+nBΞ=10.0±1.0 MeV (g.s.)
BΞ= 6.9±1.0 MeV (g.s.)
E373 Thi d E t
Attractive Potential for Ξ‐A and Ξ‐N ?
• E373 Third Event
中性子過剰ハイパー核を探る中性子過剰ハイパー核を探る ((E10 E10 実験)実験)
ハイパー核に関する研究
(K π)や (π K)反応を用いるのが主流
ハイパー核の構造ハイペロン・核子間力バリオン間力の統合的理解
通常の原子核 従来のハイパー核研究 J‐PARCで可能になる
(K,π) や (π,K) 反応を用いるのが主流 バリオン間力の統合的理解
通常の原子核 従来のハイパ 核研究ハイパー核研究
(K-,π-) 反応(π+,K+) 反応などを利用
荷電交換なし
中性子過剰ハイパー核
2重荷電交換反応(DCX)
(K-,π+)および (π-,K+) 反応を利用ハイパ 核の生成・研究
中性子過剰ハイパー核の特徴中性子多数環境のハイペロン・核子間力
ラムダ・シグマ混合中性子星の構造
ラムダ・シグマ混合の効果 中性子数とハイパー核構造の変化
中性子多数環境のハイペロン 核子間力
過剰中性子による構造変化
中性子星の構造より多様な核構造
ラムダ・シグマ混合の効果 中性子数とハイパー核構造の変化
コアが結合の強い通常の通常の原子核原子核
ラムダラムダハイパー核ハイパー核
原子核の場合ΔΔNN
ΣΣNN
原子核原子核 ハイパー核ハイパー核原子核原子核 Λ
コア核+ラムダ
nary
ΛΛNN290MeV77MeV
励起励起Λ
コアが結合の弱い原子核の場合
Ordi
ΛΛNN290MeV通常原子核の通常原子核の場合の場合の1/4 1/4 の差の差
励起励起原子核原子核
Λ
n
コア核変形(励起)
ラムダ 核子間力が強くなる
NNNN →→ 大きな混合大きな混合
ハイパー核ハイパー核
n中性子過剰
ハイパー核の場合
ハイパ 核
Exotic
ラムダ・核子間力が強くなる
中性子星の内部構造・進化
ハイパー核+中性子ハロー