jlab における高品質電子ビームを用いた...

JLab における高品質電子ビームを用いたラムダハイパー核分光実験の解析状況14aSC-4

Graduate school of science, Tohoku UniversityToshiyuki Gogami

for the HES-HKS collaborations

JLab Hall-C (2009)

Contents1. Introduction2. Experimental setup3. K+Λ electro-production4. Summary

2012/9/14 JPS meeting in Kyoto , Toshi Gogami 1

Spectroscopic experiment by (e,e’K+) reaction

pn

γ*

ΛK+

e-

e + p ➝ e’ + K+ + Λe e

target nucleus

Feynman diagram

uud

ussud

–p K+

Λ

γ*

~ 1990’s (K-,π-) , (π+,K+) reactions• Energy resolution ~ a few MeV• n Λ

e’-Spectrometer

K+-Spectrometer

pe’

pK+

Coincidence Missing Mass HHY

2

2000~(e,e’K+) reaction• Energy resolution ~500keV• p Λ

2012/9/14 JPS meeting in Kyoto , Toshi Gogami

E05-115 experimental motivation

• Light Λ hyprenuclei (7He,9Li,10Be,12B) Charge symmetry breaking Λ-Σ coupling

• Medium heavy Λ hyprenuclei (52V) s-,p-,d-,f-orbit binding energy & cross section Mass dependence of Λ single particle

energy l ・ s splitting 　∝ 2l+1

•2009 Aug – Nov @ JLab Hall-C•(e,e’K+) reaction•Target : 7Li , 9Be , 10B , 12C , 52Cr

Λ Λ Λ Λ

Λ

First try

B Λ [M

eV]

It is difficult experimentally.“ b.g. electron due to brems. ~Z∝ 2 “

A = 52

• Λ, Σ0

Energy scale calibration Elementary process


Electro-production of K+Λ

JLab E05-115 experiment by the (e,e’K+) reactionSmall Q2 ( ~0.01 [GeV/c]2 ) almost real photon

Real photon


An importance of measurement of K+Λ production at forward angles

At forward angles– Data show lack of consistency– We can access θK

cm ~ 15 deg

P.Bydzovsky and T.Mart, Phys. Rev. C 76, 065202 (2007)


JLab E05-115 experimental setup

Δp/p ~ 2×10-4

Solid angle ~ 7 [msr]θlab ~ 3 – 12 [deg] Δp/p ~ 2×10-4

Solid angle ~ 11 [msr]θlab ~ 2 – 12 [deg]

e + p → e’ + Λ + K+

7Li , 9Be , 10B , 12C , 52Cr CH2, H2O


Polyethylene(CH2) target

High intensity beam ~2.0 μA / (1×3 mm2) Hydrogen was escaping from the target

Before

After


Λ, Σ0 from CH2 target

JPS meeting in Kyoto , Toshi Gogami2012/9/14

Preliminary

8

Λ, Σ0 from CH2 target

JPS meeting in Kyoto , Toshi Gogami2012/9/14

Preliminary

9

p(e,e’K+)Λ~1.8MeV (FWHM)Δm = 19 ± 17 keV/c2

p(e,e’K+)Σ0

~1.8MeV (FWHM)Δm = 73 ± 47 keV/c2

JLab E05-115CH2, ~ 450 [mg/cm2]~ 2.0 [μA]~ 38 [hours]

Preliminary results of p(γ*,K+)Λ


Preliminary

JLab E05-115 (HES-HKS)192±6±89 [ nb / sr ]

SAPHIR : K.H.Glander et al. , Eur. Phys. J. A 19, 251-273 (2004)CLAS : R.Bradford et al. , Phys. Rev. C 73, 035202 (2006)

( JLab E05-115 , Q2 ~ 0.01 [GeV/c]2 )

Comparison with data of JLab Hall-A Large longitudinal term

contributions?

p(γ*,K+)Λ ~ JLab E05-115 (HES-HKS)W ~ 1.9 GeVQ2 ~ 0.01 [GeV/c]2

Preliminary

p(γ*,K+)Λ ~ JLab E94-107W ~ 2.2 GeVQ2 ~ 0.07 [GeV/c]2

SAPHIR : K.H.Glander et al. , Eur. Phys. J. A 19, 251-273 (2004)CLAS : R.Bradford et al. , Phys. Rev. C 73, 035202 (2006)JLab E94-107 : P.Markoviz et al. , Proceedings of SENDAI08 (2009)


Summary• JLab E05-115 (HES-HKS) was performed in JLab Hall-C in 2009

– 7ΛHe,9

ΛLi,10ΛBe,12

ΛB, 52ΛCr, Λ, Σ0

• High statistical data of p(γ*,K+)Λ– cosθCM~0.97 , W ~1.9 GeV, Q2~0.01 [GeV/c]2

• 192±6±89 [ nb / sr ]

• Further studies– Mainz MAMI-C

• Interference term (14aSC-2 : 塚田 )– JLab

• New proposal


HES-HKS Collaborations


Thank you for your attention

Prof.S.N.Nakamura

Prof.O.Hashimoto

End run party of E05-115 (Mar2010)2012/9/14 JPS meeting in Kyoto , Toshi Gogami 14

backup


Preliminary results of p(γ*,K+)Σ0

SAPHIR : K.H.Glander, Eur. Phys. J. A 19, 251-273 (2004)CLAS : R.Bradford, Phys. Rev. C 73, 035202 (2006)

JLab E05-115 (HES-HKS)62±6±26 [ nb / sr ]

( JLab E05-115 , Q2 ~ 0.01 [GeV/c]2 )

Preliminary


Detectors & TriggerK+

p, π+e-

Drift chambers

TOF walls (Plastic scintillators)

Cherenkov detectors • Aerogel (n=1.05)• Water (n=1.33)

HESHKS


Detectors & TriggerK+

p, π+e-

Drift chambers

TOF walls (Plastic scintillators)

Cherenkov detectors • Aerogel (n=1.05)• Water (n=1.33)

HESHKS

HKS trigger(TOF1x2x3) x Chrenkov

~10 kHz

HES trigger(TOF1x2)

~2000 kHz

Coincidence triggerHES x HKS

< 2 kHz2012/9/14 JPS meeting in Kyoto , Toshi Gogami 18

JPS meeting in Kyoto , Toshi Gogami

Analysis process

raw data decoding tracking x , x’ , y , y’ at Reference plane

x’ , y’ , pat target

Missing mass



F2T func. tune

F2T function

F2T function

iteration

iteration

particle ID(select K+)

HKS

HES Energy calibration (p Λ , Σ0)

2012/9/14 19


Analysis process



Missing mass



F2T func. tune

F2T function

F2T function

iteration

iteration

particle ID(select K+)

HKS

HES

2012/9/14 20

HKS detectors


K+

p, π+

Drift chambers-KDC1,KDC2-TOF walls -2X,1Y,1X-

(Plastic scintillators)

Cherenkov detectors -AC,WC-• Aerogel (n=1.05)• Water (n=1.33)

1 [m] June 2009 in JLab Hall-C

HKS trigger• CP = 1X ×1Y × 2X • K = WC × AC

CP × K

~18 [kHz](8 [μA] on 52Cr)

−π+

K+

p

σ ≈ 250 [μm]TOF σ ≈ 170 [ps]2012/9/14 21


HES DetectorsDrift chambers- EDC1 , EDC2 -

TOF walls - EH1 , EH2 - (Plastic scintillators)

HES D magnet

HES triggerEH1 × EH2

~2 [MHz](8 [μA] on 52Cr)e

Time Of Flight

σ ~ 300 [ps]

2012/9/14 22

Missing mass spectrumJLab E05-115CH2, ~ 450 [mg/cm2]~ 2.0 [μA]~ 38 [hours]

Accidental Coincidence

Quasi free Λ from 12C



p(e,e’K+)Λ~1.8MeV (FWHM)Δm = 19 ± 17 keV/c2

p(e,e’K+)Σ0

~1.8MeV (FWHM)Δm = 73 ± 47 keV/c2


e-

e’ K+

Considered efficiencies

Simulation


K+ production at small angles

TLTTLTfull )1(2 electroproduction

SL: 0.41 = 0.35 + 0.004 - 0.001 + 0.06 ( = 0.7 )

a steep

Q2 dependence ?

P. Bydzovsky’s presentation at ECT* 2011

(g*,K+)JLab Hall-A

E05-115W=1.9 GeVQ2=0.01 (GeV/c)2


Electro-production of K+Λ

JLab E05-115 experiment by the (e,e’K+) reactionSmall Q2 ( ~0.01 [GeV/c]2 ) almost real photon

,


Estimation of the number of events by the fitting

~Lambda~ Number : 6402.57 Mean : 28.5527 +- 19.7152 [keV/c2] ( Delta Mean : 28.5527 +- 19.7152 [keV/c2] ) Width : 1937.59 +- 52.1221 [keV/c2]

~Sigma~ Number : 1688.07 Mean : 76809.3 +- 42.7735 [keV/c2] ( Delta Mean : -149.659 +- 42.7735 [keV/c2] ) Width : 1848.15 +- 121.343 [keV/c2]

Fitting function :

peak background

B : Half width at half maximumC : Center value


Cut conditions to make the missing mass

• Cut conditions– 1.0 > NWC1+2

– 5.0 < AC1+2+3

– -1.0 < coincidence time + 54.9 < 1.0– 0.08 < Mass square < 0.44– HKS tracking chi-square < 150.0– HES tracking chi-square < 150.0


K+ survival Ratio after the mass square cut (CH2)

If applied these two cut at the same time(Suv. Ratio)total = (Suv. Ratio1) + (Suv. Ratio2) – 1.0

Suv. ratio1 Suv. ratio2

Cut 2Cut 1

K+ survival ratio


K+ survival ratio after AC cut (CH2)

(accut,wccut) = (5,-0.1)pi suv. ratio: 0.0631439+-0.00148976K suv. ratio: 0.876875+-0.00513167p suv. ratio: 0.911427+-0.0023794



Stricter cut of AC NPE

looser cut of AC NPE

π+K+

p

π+K+

p


K+ survival ratio after WC cut (CH2)

(accut,wccut) = (2000,1.1)pi suv. ratio: 0.922368+-0.00752531K suv. ratio: 0.987653+-0.00566791p suv. ratio: 0.133889+-0.000701787

(accut,wccut) = (2000,1)pi suv. ratio: 0.963952+-0.00777583K suv. ratio: 0.989093+-0.0056741p suv. ratio: 0.176933+-0.000821917

(accut,wccut) = (2000,0.9)pi suv. ratio: 0.971601+-0.00782181K suv. ratio: 0.999575+-0.00571909p suv. ratio: 0.259314+-0.00102927

Stricter cut of WC NPE

looser cut of WC NPE

π+K+

p

π+K+

p2012/9/14 JPS meeting in Kyoto , Toshi Gogami 32

Tracking efficiencies• ~~~~ HKS~~~~~~~

ch2 : Tracking Efficiency : 0.998974 +- 0.00760814 (0.761596%)h2o : Tracking Efficiency : 0.961109 +- 0.00190445 (0.198152%)li : Tracking Efficiency : 0.996378 +- 0.0205954 (2.06703%)be : Tracking Efficiency : 0.995274 +- 0.00535923 (0.538468%)b : Tracking Efficiency : 0.99921 +- 0.00912634 (0.913356%)c : Tracking Efficiency : 0.987929 +- 0.00179032 (0.181219%)cr1 : Tracking Efficiency : 0.974892 +- 0.00304261 (0.312097%)cr2 : Tracking Efficiency : 0.965851 +- 0.00320905 (0.332251% )

• ~~~~ HES~~~~~~~ch2 : Tracking Efficiency : 1 +- 0.00527844 (0.527844%)h2o : Tracking Efficiency : 1 +- 0.00095474 (0.095474%)li : Tracking Efficiency : 1 +- 0.0172701 (1.72701%)be : Tracking Efficiency : 1 +- 0.00419163 (0.419163%)b : Tracking Efficiency : 1 +- 0.00820523 (0.820523%)c : Tracking Efficiency : 1 +- 0.00153384 (0.153384%)cr1 : Tracking Efficiency : 1 +- 0.00100727 (0.100727%)cr2 : Tracking Efficiency : 1 +- 0.00103985 (0.103985%)

1 ….!?Need to check tracking code


HKS efficiency

• εHKS = 0.169– AC : 0.877 (+-0.005)– WC : 0.990 (+-0.006)– Tracking : 0.999 (+0.001, - 0.007)– M2 : 0.96– Ctime : 0.99– fdecay : 0.252 (± 0.006)

– fburn : 0.82


Definition of the cross section

εcommon ~ 0.97SIMULATION

-5


Theta and Momenta of the scattered electrons


Angular acceptance cut

θe’ > 0.05 rad


Back ground estimation

Optimal scaling factor 1.08

Black + (Green × scaling factor) = Blue

∑ (Residual of Black and Blue )2Scaling factor : 1.


Current missing mass spectrumJLab E05-115CH2, ~ 450 [mg/cm2]~ 2.0 [μA]~ 38 [hours]


Current missing mass spectrumJLab E05-115CH2, ~ 450 [mg/cm2]~ 2.0 [μA]~ 38 [hours]

Accidental Coincidence

Quasi free Λ from 12C


The number of events of Λ and Σ0

5760 　 ± 125(Integrated : -5 – 9 MeV/c2)

1579 　 ± 94(Integrated : 72 – 86 MeV/c2)

ΛΣ0



Momentum acceptance cut (Σ0)

HES momentum region1. 0.770 – 0.9002. 0.770 – 0.8353. 0.835 – 0.900

52ΛV g.s.

~8.5 msr


Momentum acceptance cut (Λ)

HES momentum region1. 0.770 – 0.9002. 0.770 – 0.8353. 0.835 – 0.900

52ΛV g.s.

~8.5 msr


Momentum acceptance cut~8.5 msr

HES momentum region1. 0.770 – 0.900 GeV/c2. 0.770 – 0.835 GeV/c3. 0.835 – 0.900 GeV/c

ΛΣ0


Momentum acceptance cut~8.5 msr

HES momentum region [ GeV/c ]

0.790 ~ 0.844( 1.922 < W [ GeV ] < 1.947 )

ΛΣ0


Data Summary

JLab E05-115 (2009/June – 2009/Nov)

JPS meeting in Kyoto , Toshi Gogami 472012/9/14

Singles rate summaryUp to ~30 [MHz]

Up to ~15 [MHz]HES

HKS

HKS trigger ~ 10[kHz]

HES trigger ~ a few[MHz]

COIN 2.0 [kHz]


Hit wires event display (2)

• GREEN region Selective region• RED markers & lines Selected hit wires• BLACK markers & lines Rejected hit wires

v v’ u u’

x x’

v v’ u u’

x x’

KDC1 KDC2particle particle


KTOF multiplicity ~2.7 ~1.8

~6.5 ~3.8

CH2 , 76314 52Cr , 77124Multiplicity of KDC are not only high but also TOF counters are! (for heavy target )


Background event from NMR port

z [cm]

y [cm]

x [cm]

These particles come from NMR port

HKS dipole magnet

NMR port

KDC1

KDC2

KDC1

KDC2

KDC1

KDC2

KDC1

KDC2

Background events

9Be , 38.4 [μA]

9Be , 38.4 [μA] 9Be , 38.4 [μA]

Events on HKS optics

Overhead view

Side view

Β ≈ 1e- , e+


B.G. mix rate (real data)

ab

B.G mix rate =

* hks ntulpeJPS meeting in Kyoto , Toshi Gogami 522012/9/14

e+ simulation

SIMULATION

• To see 1. Number of event2. Angle & momentum

of e+ generated in target


Target thickness dependence(Simulation)

H2O52Cr9Be

12C CH2

10B

7Li

Consistent with B.G. mix rate !

SIMULATION


Angle and momentum distribution of positrons

HKS cannot accept positrons directly !

Generate these event in HKS GEANT(Next page)

SIMULATION


e , e+ background in GEANT simulation

Vacuum chamber(sus304)

NMR port(sus304)

KDC1 KDC2

e- , e+

• Generated particle : e+

• Distribution : spherical uniform• Momentum : 860 – 1000 [MeV/c]• Angle : 0 – 2 [mrad]• 1000 events

Number of e+ (Simulation) B.G. mix rate (Real data)Correlation

e+ generated in target make HKS dirty


Apply to u,v-layer

Applied to uu’ and vv’ layers , too.

Selective region determined by 1X and 2X

Convert

v v’-layer

x x’-layer


Hit wires event display (2)

• GREEN region Selective region• RED markers & lines Selected hit wires• BLACK markers & lines Rejected hit wires

v v’ u u’

x x’

v v’ u u’

x x’

KDC1 KDC2particle particle


Spectroscopic experiment by (e,e’K+) reaction

pn

γ*

ΛK+

e-

e + p ➝ e’ + K+ + Λe e

target nucleus

Feynman diagram

uud

ussud

–p K+

Λ

γ*

1. Large Momentum transfer• Λ can be bounded in deeper orbit

2. Λ’s spin at forward angle• Spin flip ~ spin non-flip

3. Proton Λ• Absolute mass value calibration

e’-Spectrometer

K+-Spectrometer

pe’

pK+

Coincidence Missing Mass HHY


JLab E05-115 experimental setup

2×10-4

7 [msr]3 – 12 [deg]

2×10-4

8.5 [msr]2 – 12 [deg]

e + p → e’ + Λ + K+

7Li , 9Be , 10B , 12C , 52Cr

• (e,e’K+) experiment 1. Coincidence experiment (K+ and e-)2. Small cross section ( ~100 [nb/sr] ) 1/10003. Energy resolution Sub MeV (FWHM)

Primary beam• High intensity

Thin target (~100 [mg/cm2])• High quality



JLab CEBAF ( Continuance Electron Beam Accelerator Facility )

• (e,e’K+) experiment 1. Coincidence experiment (K+ and e-)2. Small cross section ( ~100 [nb/sr] ) 1/10003. Energy resolution sub MeV (FWHM)

100 [m]

• Requirements for accelerator1. High duty factor (~100%)2. High intensity ( >a few 10 μA )3. Small emittance ( ~2 [mm ・ μrad] ) Small ΔE/E ( <1×10-4 )

CEBAF was unique facility

before MAMI updated

Experimental Hall

612012/9/14

Coincidence time vs. Mass square


Cherenkov cut


Cherenkov light


HES の構成ED1Max. Field Gradient 7.8[T/m]Max. Current 800[A]Total magnet weight 2.8[ton]EQ2Max. Field Gradient 5.0[T/m]Max. Current 800[A]Total magnet weight 3.1[ton]EDMax. Field 1.65[T]Max. Current 1065[A]Total magnet weight 36.4[ton]


Λ hypernuclear spectroscopy

Updated from: O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys. 57 (2006) 564.

52LV


(e,e’K+) experiment in JLab2000

1st generation exp. JLab E89-009e’-spectrometer + K+-spectrometer

12ΛB

~ 750 [keV] (FWHM)

2005 2nd generation exp. JLab E01-011

e’-spec. Optimized configuration + HKS(K+)7

ΛHe,12ΛB,28

ΛAl~ 600 [keV] (FWHM)

2009 3rd generation exp. JLab E05-115

HES(e’) Optimized configuration + HKS(K+)7

ΛHe,9ΛLi,10

ΛBe, 12ΛB,52

ΛV≤ 500 [keV] (FWHM)

Proof of feasibility

Establish exp. method

Up to Medium heavy

Final analysis stage

2004 JLab E94-107

(K+, e+)-spectrometers + septum9

ΛLi,12ΛB,16

ΛN~ 670 [keV] (FWHM)

Hall-C

Hall-C

Hall-C

Hall-A

Analyzing

Avoid huge background at very forward angle


Analysis status of E05-115

• p(e,e’K+)Λ,Σ0

HES-HKS basic system works well

~40 hours(5 shifts)

JLab E05-115p(e,e’K+)Λ,Σ0

Very preliminary• Analysis is in progress

1. Energy (mass) calibration2. Developing new code for high multiplicity

data

E.M background ~Z∝ 2

Λ and Σ0 can be seen at the same time

2009 3rd generation exp. JLab E05-115

HES(e’) Optimized configuration + HKS(K+)7

ΛHe,9ΛLi,10

ΛBe, 12ΛB,52

ΛV≤ 500 [keV] (FWHM)

Up to Medium heavy

Hall-CJPS meeting in Kyoto , Toshi Gogami 682012/9/14

Experimental data of A=7 system

Old 7ΛHe data

( M.Juric, NPB 52, 1973 )

-BL [MeV]

-6.650.03 0.2 MeV from α L n n

JLab E01-0117Li(e,e’K+)7

ΛHe

Compare to theoretical calculation

Preliminary

Four-body cluster model for T=1 iso-triplet hypernuclei(E.Hiyama et al., NPC 80, 2009)α + Λ + N + N



Theoretical calculation of A=7 systemFour-body cluster model for T=1 iso-triplet hypernuclei(E.Hiyama et al., NPC 80, 2009)α + Λ + N + N

Old 7ΛHe data

( M.Juric, NPB 52, 1973 )

-BL [MeV]

-6.650.03 0.2 MeV from α L n n


ΛHe

Compare to theoretical calculation

Preliminary

702012/9/14

Theoretical calculation of A=7 system

-BL (MeV)

-6.650.03 0.2 MeV from α L n n

Four-body cluster model for T=1 iso-triplet hypernuclei(E.Hiyama et al., PRC 80, 2009)α + Λ + N + N


ΛHe

CSB interaction is determined to reproduce BΛ of 4

ΛH and 4ΛHe.

Will be talked by E.Hiyama in Plenary 6 session(8/24)

Decay pion spectroscopy

Preliminary

-5.41


Summary• (e,e’K+) spectroscopic exp. in JLab

– E89-009 (2000,Hall-C) 12ΛB

– E94-107 (2004,Hall-A) 9ΛLi,12

ΛB,16ΛN

– E01-011 (2005,Hall-C) 7ΛHe,12

ΛB,28ΛAl

– E05-115 (2009,Hall-C) 7ΛHe,9

ΛLi,10ΛBe, 12

ΛB,52ΛV

• Precision light Λ hypernuclear spectroscopy– 7

ΛHe (preliminary result by E01-011) – 10

ΛBe (analyzing)

Analysis stage

Final analysis stage

ΛN charge symmetry breakingJPS meeting in Kyoto , Toshi Gogami 722012/9/14

JPS meeting in Kyoto , Toshi Gogami 73

EndThank you very much

Experimental hall-C, JLab (2009)

2012/9/14

(e,e’K+) reaction

uud

ussud

e e

–p K+

Λ

γ*

ud

ddu

us

sdu

– –π+

Λn

us

ddu

ud

sdu

–K-

Λn

–π-

e + p ➝ e + K+ + Λ π+ + n ➝ K+ + Λ

K+

K- + n ➝ π- + Λ(π+ , K+) (K- , π-)(e,e’K+)

Momentum transfer(Typical )

~300 [MeV/c] ~300 [MeV/c] ~90 [MeV/c]

Λ’s SpinAt forward angle

Λ’s from proton neutron neutron

flip ≈ non-flip non-flip non-flip

Beam primary secondary secondary

Target Thin (~100 mg/cm2)(Isotopically enriched) Thick(> a few [g/cm2] ) Thick(> a few [g/cm2] )

Reaction

Λ can be bounded in deeper orbit

Spin dependent structure

Mirror lambda hypernuclei

High quality , high intensity

Fine structureEnergy resolution

(FWHM)≤ 500 [keV] 1 – 3 [MeV] 1 – 3 [MeV]JPS meeting in Kyoto , Toshi Gogami 742012/9/14

HKS detectors

K+

p, π+

Drift chambers-KDC1,KDC2-TOF walls -2X,1Y,1X-

(Plastic scintillators)

Cherenkov detectors -AC,WC-• Aerogel (n=1.05)• Water (n=1.33)

1 [m] June 2009 in JLab Hall-C

HKS trigger• CP = 1X ×1Y × 2X • K = WC × AC

CP × K

~18 [kHz](8 [μA] on 52Cr)

−π+

K+

p

σ ≈ 200 [μm]TOF σ ≈ 170 [ps]JPS meeting in Kyoto , Toshi Gogami 752012/9/14


HES DetectorsDrift chambers- EDC1 , EDC2 -

TOF walls - EH1 , EH2 - (Plastic scintillators)

HES D magnet

HES triggerEH1 × EH2

~2 [MHz](8 [μA] on 52Cr)e

Time Of Flight

σ ~ 300 [ps]

762012/9/14

Target hypernucleus thickness[mg/cm2]

beam current[μA]

total charge[C]

number of QF Λ (online)

expected number of

g.s.7Li 7He 184.0 32.0 4.84 6.4E+4

(1.0 μb/sr)~1000

(20 nb/sr)9Be 9Li 188.1 38.3 5.33 4.5E+4

(1.2 μb/sr)~200

(5 nb/sr)10B 10Be 56.1 38.7 6.25 4.8E+4

(1.3 μb/sr)~800

(20 nb/sr)12C 12B 112.5 26.8 5.90 3.4E+4

(1.5 μb/sr)~2000

(100 nb/sr)52Cr 52V 134.0

154.07.6 0.83

5.538.0E+3

(4.7 μb/sr)~100

(70 nb/sr)

Data summary


Λ

Λ

Λ

Λ

Λ

E05-115 ( 2009 Aug – Nov )

measuredassumption

Target hypernucleus thickness[mg/cm2]

beam current[μA]

total charge[C]

CH2 Λ , Σ0 450.8 2.0 0.28

H2O Λ , Σ0 ~500.0 2.7 0.20

Physics Data

Calibration Data

772012/9/14

E01-011


L and S spectra (CH2 target)

c.f. E89-009, 183 hours (8.8 mg/cm2, 0.5 or 1.0 uA)T. Miyoshi et al., Phy. Rev. Lett. 90, 232502(2003)

Better resolution and statistics

~ 3.5 MeV (FWHM)

L1.9 MeV (FWHM) S

2.3 MeV (FWHM)

E01-011 ~70 hours (450 mg/cm2, 1.5 uA)


Background subtraction

Accidental background : polynomial functionJPS meeting in Kyoto , Toshi Gogami 802012/9/14

GEANT412C 100 mg/cm2

Effect of simple gaussian fit:D= +20 keV

count difference : -30 %


12C(e,e’K+)12LB

Resolution : ~470 keV (FWHM) for g.s.Data taking : ~30 hours w/ 30 mA

Fitting Result

#1 #2

Two major peaks#1 : [(p3/2)-1

p,(s1/2)L]#2 : [(p3/2)-1

p,(p3/2,p1/2)L]

(126)(130)


#1 #2

12C(e,e’K+)12LB, 12C(p+,K+)12

LC


12C(e,e’K+)12LB

#1 #2


12C(e,e’K+)12LB

Red : calculation with SLAGreen : calculation with KMAID

Theory by Sotona et. al. (1.3 < Eg < 1.6 GeV, 1 < qK < 13 deg.)

Result

#1Jp Ex

[MeV]Cross section [nb/sr]

SLA KMAID

1-

2-

00.14

19.765.7

20.743.0

2+

3+

10.9911.06

48.375.3

38.068.5

#2

ID Ex [MeV]

Cross section [nb/sr]

Cross section (Calc., SLA) [nb/sr]

#1 0 97±3.9 (stat.) +29,-22 (sys.)

85.4(1- + 2-)

#2 11.18±0.01 (stat.) ±0.10 (sys.)

100±3.8 (stat.) +30, -30 (sys.)

123.6(2+ + 3+)

(126)

(130)JPS meeting in Kyoto , Toshi Gogami 852012/9/14

12C(e,e’K+)12LB

• Two major peaks ; #1:[(p3/2)-1p,(s1/2)L],

#2:[(p3/2)-1p,(p3/2,p1/2)L]

– Consistent -BL with previous exp.– Different width for g.s. with E94-107 data– Ex and cross sections : agree with shell model

calculation• Best resolution of 470 keV (FWHM) for g.s.


28Si(e,e’K+)28LAl

Resolution : ~450 keV (FWHM) for g.s.Data taking : ~30 hours w/ 30 mA

#1 #2#3

Fitting Result

Three major peaks#1 : [(d5/2)-1

p,(s1/2)L]#2 : [(d5/2)-1

p,(p3/2,p1/2)L]#3 : [(d5/2)-1

p,(d5/2,d3/2)L]

First sd-shell hypernuclear spectroscopy by (e,e’K+)

(78)(122)(77)JPS meeting in Kyoto , Toshi Gogami 872012/9/14

Shell model calculation

Full space (0d5/20d3/21s1/2)pn

11,12

DWIAYNG interaction


#1 #2 #3

28Si(e,e’K+)28LAl, 28Si(p+,K+)28

LSi


28Si(e,e’K+)28LAl

Theory by Sotona et. al. (1.3 < Eg < 1.6 GeV, 1 < qK < 13 deg.)#1Jp Ex

[MeV]Cross section [nb/sr]

SLA KMAID

2+,3+ 0 92.1 71.76

4-

3-

9.429.67

134.991.3

117.558.5

4+

5+

17.617.9

148.4139.1

135.189.9

#2#3

ID Ex [MeV]

Cross section [nb/sr] Cross section (Calc. SLA) )[nb/sr]

#1 0 60±5.0 (stat.) +27, -18 (sys.)

92.1(2+ + 3+)

#2 10.98±0.02 (stat.) ±0.30 (sys.)

94±6.0 (stat.) +43, -28 (sys.)

226.2(4- + 3-)

#3 19.30±0.03 (stat.) ±0.30 (sys.)

59±6.7 (stat.) +55, -18(sys.)

287.5(4+ + 5+)


Result

(78)

(122)

(77)JPS meeting in Kyoto , Toshi Gogami 902012/9/14

28Si(e,e’K+)28LAl

• First sd-shell hypernuclear spectroscopy by (e,e’K+)• Three major peaks ; #1:[(d5/2)-1

p,(s1/2)L], #2:[(d5/2)-1

p,(p3/2,p1/2)L] #3:[(d5/2)-1

p,(d5/2,d3/2)L]– Deeper -BL for g.s. than 28

LSi and shell model calculation– Wider energy spacing between #1 and #2 than calc.– Narrower energy spacing between #2 and #3 than calc.– Smaller cross sections than calc.


7Li(e,e’K+)7LHe

#1

Observation of 7LHe w/ good statistics

Fitting Result (40)JPS meeting in Kyoto , Toshi Gogami 922012/9/14

-BL= -5.36 w/o CSB -5.16 w/ CSB

CSB effect by cluster modelFour-body cluster model

E.Hiyama et al.PRC80,054321(2009)

L

NN

a

Phenomenological potential


7Li(e,e’K+)7LHe

Jp -BL [MeV]

Cross section [nb/sr]

SLA KMAID

1/2+ -5.36 13.2 9.7

Theory by Sotona et. al. (Cross section) by Hiyama et. al. ( -BL : w/o CSB)(1.3 < Eg < 1.6 GeV, 1 < qK < 13 deg.)

Result

#1

ID -BL

[MeV]Cross section

[nb/sr]

#1 -5.71±0.02 (stat.) ±0.20 (sys.)

31±2.8 (stat.) +11.8,-9.3 (sys.)


(40)


7Li(e,e’K+)7LHe

• High statistics spectroscopy• -BL=-5.71±0.02 (stat.)±0.20 (sys.) for g.s.

– Cluster model calculation-BL=-5.36 (w/o CSB)-BL=-5.16 (w/ CSB)

• Cross section : larger than shell model calc.


E01-011 ~Count, S/N~Peak ID # of peak

[counts]# of BG(3)

[counts]S/N Sys. Err.

(Contami. -%)Sys. Err.

(Loss +%)7LHe:#1 120 230 0.52 30 30

12LB:#1 630 561 1.12 5 30

12LB:#2 695 706 0.98 20 30

28LAl:#1 145 360 0.40 40 30

28LAl:#2 240 516 0.47 40 30

28LAl:#3 77 545 0.14 90 30


jlab に おける高品質電子ビームを用いた...

Documents

jlab における高品質電子ビームを用いた...