4 th sep 2010 satoshi n nakamura tohoku university
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4 th Sep 2010 Satoshi N Nakamura Tohoku University. JSPS Core2CORE/SPHERE Meeting . Overview and Status of JLab Hall-C Hypernuclear Experiments. The A Z( e,e’K + ) A L (Z-1) reaction for hypernuclear spectroscopy. ( p ,K ) reaction established hypernuclear reaction spectroscopy

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4 th sep 2010 satoshi n nakamura tohoku university

4th Sep 2010

Satoshi N Nakamura

Tohoku University

JSPS Core2CORE/SPHERE Meeting

Overview and Status of JLab Hall-C

Hypernuclear Experiments


The a z e e k a l z 1 reaction for hypernuclear spectroscopy

The AZ(e,e’K+) AL(Z-1)reaction for hypernuclear spectroscopy

(p,K) reaction established hypernuclear reaction spectroscopy

(e,e’K) has similar features with better resolution

AZ

p

AL(Z-1)


Characteristics of e e k hy study

Characteristics of (e,e’K) HY study

  • Electromagnetic production

    • Photo/electron strangeness production

  • Proton goes to Lambda

  • Both spin flip and non-spin flip amplitudes

  • High quality primary beam

    • High energy resolution (< 1MeV)

    • Thin enriched target

Real photon (g,K) HY spectroscopy is practically impossible.

Eg. JLab-CLASBremsstrahlung tagged photon

~ 5o MHz, 10-3 E0 = 2 MeV for 2 GeV


Early works em production of l hypernucleus

Early works : EM production of L Hypernucleus

12C(g,K+)12LB

3He(e,e’K+)3LH

4He(e,e’K+)4LH

ES132 @INS-TAGX, PRC 52 (1995) 1157.

NEXT STEP: Spectroscopy with

mass resolution of sub-MeV

E91-016 @ JLab-HallC , PRL 93(2004)242501


Definition of kinematic parameters

Definition of Kinematic Parameters


Elementary p g k l

Elementary p(g,K+) L

Eg ~ 1.5 GeV

Eg ~ 2.2 GeV

R.A.Schmacher for CLAS

s for elementary process

Max. at Eg ~ 1.5 GeV

Lower Eg : Close unnecessary reaction channel

HigherEg : Smaller K decay loss, Larger L trapping rate


Hypernucleus recoil momentum for various reactions

12C target

Hypernucleus recoil momentum for various reactions

Exoergic

Endoergic

1.5GeV/c


P e e k l cross section

p(e,e’K)L Cross Section

  • Virtual but almost real photon

E01-011 : Q2 ~ 0.01 (GeV/c)2 , qe~6.5 deg.

e ~ 0.04, eL~1.7x10-4


Angular dependences

Angular Dependences

0.3 GeV/c, e’

1.8 GeV, e

L

1.5 GeV, g*

1.2 GeV/c, K+

p

Both of e’ & K+ are forward.


Challenge of e e k hy study

Challenge of (e,e’K) HY Study

  • Large e’ Background due to Bremsstrahlung and Mfller scattering

    Signal/Noise, Detector

  • Less Hypernuclear Cross Section

  • Coincidence Measurement (e’, K+)

    Limited Statistics, DC beam is necessary

High Quality Electron Beam is Essential !


Beam requirements

Beam requirements

  • Continuous beam for coincidence exp.

  • Electron beam E > 1.5 GeV

  • High current beam > 30mA

  • Beam stability

    • Momentum Dp/p < 1 x 10-4

    • Good emittance : sx < 100mm, sx’ <1mrad

Until upgrade of MAMI-C, CEBAF had been only facility

for this program.


First generation experiment

First Generation Experiment

SPL + SOS +HMS

E89-009 (HNSS; HyperNuclear Spectrometer System)


The first e e k hypernuclear experiment e89 009 hnss

Data taking year 2000

The first (e,e’K+) hypernuclear experiment (E89-009, HNSS)

12C(e,e’K+) 12LB

  • Demonstrated that

    the (e,e’K) hypernuclear spectroscopy is possible!

pL

sL

Good energy resolution

<800 keV (FWHM)

Best hypernuclear energy resolution achieved by the reaction spectroscopy

at that time

PRL 90 (2003) 232502, PRC 73 (2006) 044607


Improvement of the e89 009 experiment

Improvement of the E89-009 experiment

ct (K+) ~4m

  • Energy resolution as well as acceptance are limited by the kaon spectrometer (SOS)

New Spectrometer

High resolution Kaon Spectrometer(HKS)

  • Zero degree tagging method to maximize virtual photon flux

Severe background from electrons associated with

Bremsstrahlung (200 MHz for e’ arm)

Tilt Method

The 2nd Generation Experiment was approved by Jlab PAC19

E01-011 (Spokesmen: Hashimoto, Tang, Reinhold, Nakamura)


Jsps core2core sphere meeting

Second Generation Exp. at JLab

To beamdump

HKS

ENGE

Splitter

Target

Electronbeam

2005 E01-011 (Hall C)

First step to midium heavy hypernuclei (28Si, 12C, 7Li)

Two Major Improvements

New HKS

Tilt Method

Beam: 30 μA , 1.8GeV

HKS:Δp/p=2 x 10 -4 [FWHM]

Solid angle 16msr(w/ splitter)


Tilt method

Tilt method

Background electrons

  • Bremsstrahlung

    very forward peaked

  • Møller scattering

    scattering angle and momentum are correlated

to avoid them

e’

8 degree

Tilt Enge spectrometer

by 8 degree

(optimization of e’

detectionangle)


Second generation exp e01 011 setup

Second Generation Exp.E01-011 setup

K+ 1.2 GeV/c

e’ 0.3 GeV/c

HKS (newly designed)

e

1.8 GeV


L and s spectra ch 2 target

L and S spectra (CH2 target)

Absolute mass scale calibration

E01-011

~70 hours

(450 mg/cm2, 1.5 uA)

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)

L

L

1.9 MeV

(FWHM)

S

2.3 MeV

(FWHM)

S0

~ 3.5 MeV

(FWHM)

Better resolution and statistics


Highlights of e01 011 results

Highlights of E01-011 Results

To be published soon.

12LB : Reference Spectrum w/ best resolution

28LAl : First beyond-p shell HY. by (e,e’K)

7LHe : First reliable data, CSB effect


12 c e e k 12 l b 12 c p k 12 l c

12C(e,e’K+)12LB, 12C(p+,K+)12LC

Emulsion


12 l c emulsion data

12LC emulsion data

11C (3/2-) : Ex = 4.8MeV

Reference for all (p, K) BL data:

BL (12LCg.s.) = 10.76 +-0.19MeV

Statistical error only


12 l b emulsion data

12LB emulsion data

(# of events)

BL (12LBg.s.) = 11.45 +-0.07 MeV

Emulsion Result (M.Juric et al.)

Ref) A=4 System

Different modes

give 0.22 MeV

difference

Systematic Error?


12 c e e k 12 l b @ jlab hall c a

#2

#1

12C(e,e’K+)12LB @ JLab Hall C & A

Binding energies are consistent with

The other (e,e’K) data.


12 l b emulsion data1

12LB emulsion data

(# of events)

BL (12LBg.s.) = 11.45 +-0.07 MeV

Emulsion Result (M.Juric et al.)

Totally Independent Measurement

BL (12LBg.s.) = 11.40 +-0.01+-0.14MeV

E01-011 Result (A.Matsumura Ph.D. Thesis)

Ref) A=4 System

Decay p spectroscopy is important

Different modes

give 0.22 MeV

difference

Systematic Error?


28 si e e k 28 l al 28 si p k 28 l si

#3

#1

#2

28Si(e,e’K+)28LAl, 28Si(p+,K+)28LSi

First sd-shell hypernuclear

spectroscopy by (e,e’K+)


28 si e e k 28 l al @ jlab hall c

#3

#1

#2

28Si(e,e’K+)28LAl @ JLab Hall C

Full space

(0d5/20d3/21s1/2)pn11,12

DWIA

YNG interaction


7 li e e k 7 l he

7Li(e,e’K+)7LHe

First reliable observation of 7LHe w/ good statistics

#1

M.Juric et al. NP B52 (1973) 1

Detailed Discussion : Tomorrow


Jsps core2core sphere meeting

CSB effect by cluster model

Four-body cluster model

A=4, T=1/2 System

n

L

L

n

4LH, 4LHe

p

p

p

n

A=7, T=1 iso-triplet

7LHe, 7LLi*, 7LBe

a

a

a

a

a

L

L

L

L

L

A=10, T=1/2 system

p

p

n

n

n

n

10LBe, 10LB

p

p

a

a


Hypernuclei in wide mass range

E01-011

7Li 12C 28Si

Hypernuclei in wide mass range

E89-009

12C

1

20

50

200

1057

A

Elementary Process

Neutron/Hyperonstar,

Strangeness matter

Strangeness electro-production

Light Hypernuclei (s,p shell)

Hyperonization

Softening of EOS ?

Fine structure

Baryon-baryon interaction in SU(3)

LS coupling in large isospinhypernuclei

Cluster structure

Medium - Heavy hypernuclei

Single-particle potential

Distinguishability of a Lhyperon

U0(r), mL*(r), VLNN, ...


Hypernuclei in wide mass range1

E05-115

E01-011

7Li 12C 28Si

Hypernuclei in wide mass range

E89-009

12C

1

20

50

200

1057

A

6,7Li 10,11B 12C 51V 52Cr

Elementary Process

Neutron/Hyperonstar,

Strangeness matter

Strangeness electro-production

Light Hypernuclei (s,p shell)

Hyperonization

Softening of EOS ?

Fine structure

Baryon-baryon interaction in SU(3)

LS coupling in large isospinhypernuclei

Cluster structure

Medium - Heavy hypernuclei

Single-particle potential

Distinguishability of a Lhyperon

U0(r), mL*(r), VLNN, ...

3rd Generation Experiment


Jsps core2core sphere meeting

Third Generation Exp. at JLab

2009 E05-115 (Hall C)

Wide mass range hypernuclearspectroscopy (52LV, 12LB ,10LBe, 9LLi, 7LHe )

Major Improvements

(10 times more VP tagging )

New HES

best match to HKS

New Calibrations

H2O cell target

Beam energy scan


Goals of the 3 rd generation experiment

Goals of the 3rd Generation Experiment

  • 7Li(e,e’K+)7ΛHe,10B(e,e’K+)10ΛBe

  • - Cluster model, shell model approach

    • Charge Symmetry Breaking in LN interaction

    • LN-SN coupling effect

  • 52Cr(e,e’K+)52ΛV

  • - Shell model, Mean field theory

    • A dependence of L single particle energies

    • Measurement of fine structure (core configuration mixing, ls splitting…)

SPHERE and JSPS 2010 Meeting


Missing mass calibration data

Missing mass calibration data

Elementary process of

Electromagnetic production of strangeness

CH2 target missing mass

L

Analysis Status

By Kawama

S0

Mx-ML [MeV]

E05-115 (2009) preliminary


L single particle energies

L single particle energies

JLab E05-115

JLab E01-011


Summary

Summary

  • With a high quality electron beam from CEBAF,

    (e,e’K) hypernuclear spectroscopy was established

  • The second gen. exp. E01-011 (HKS) achieved ~500keV (FWHM) resolution

    12B : reference data with the best resolution

    7He : first reliable observation of g.s., CSB

    28Al : first observation, doorway to mid-heavy HY

  • The third gen. exp. E05-115 (HKS-HES) successfully finished

    L, S0 , 7He, 9Li, 10Be, 12B, 52V


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