Recent results from Recent results from the Hall C hypernuclear programthe Hall C hypernuclear program

- JLab E01-011 -

Osamu HashimotoOsamu HashimotoTohoku UniversityTohoku University

HYP2006Mainz, October 11-14, 2006

E01-011 hypernuclear E01-011 hypernuclear collaborationcollaboration

– Y. Fujii, O. Hashimoto (Spokesperson), D. Honda, M. Kaneta, F. Kato, D. Kawama, A. Matsumura, N. Maruyama ,T. Miyoshi, S.N. Nakamura (Spokesperson), H. Nomura, K.Nonaka ,A. Ohtani, Y. Okayasu, M. Sumihama, H. Tamura (Tohoku U)

– S. Kato (Yamagata U)– T. Takahashi, Y. Sato, H. Noumi (KEK)– O.K. Baker, M. Christy, L. Cole, P. Gueye, C. Keppel, L. Tang (Spokesperson),

L. Yuan (Hampton U)– B. Beckford, S. Gullon, P. Markowitz, J. Reinhold (Spokesperson), C. Vega (FlU)– Ed.V. Hungerford, K. Lan, N. Elhayari, N. Klantrains, Y. Li,S. Radeniya , Murad, V.

Rodrigues (Houston)– R. Carlini, R. Ent, H. Fenker, T. Horn, D. Mack, G. Smith, W. Vulcan, S.A. Wood, C.

Yan (JLab)– N. Simicevic, S. Wells (Louisiana Tech)– L. Gan (North Carolina, Wilmington)– A. Ahmidouch, S. Danagoulian, A. Gasparian (North Carolina A&T)– M. Elaasar (New Orleans)– R. Asaturyan, H. Mkrtchyan, A. Margaryan, S. Stepanyan, V. Tadevosyan

(Yerevan)– D. Androic, T. Petkovic, M. Planinic, M. Furic, T. Seva (Zagreb)– T. Angelescu (Bucharest)– V.P. Likhachev (Sao Paulo)– M. Ahmed (Duke)– B. Hu, Y. Song, C. Yang (Lanzhou)

1989 The first hypernuclear experiment in1989 The first hypernuclear experiment in Hall C, E89-009, approved 1994 Hypernuclear experiment in1994 Hypernuclear experiment in Hall A, E94-107, approved1995 JLab started physics experiments1995 JLab started physics experiments1997 Hall C 21997 Hall C 2ndnd generation experiment, E97-008, approved, later updated as E01-011 generation experiment, E97-008, approved, later updated as E01-0112000 2000 The first (e,e’K+) hypernuclear spectroscopy, E89-009, carried out2002-20032002-2003

High resolution kaon spectrometer (HKS) for the E01-011 experiment under constructiHigh resolution kaon spectrometer (HKS) for the E01-011 experiment under constructionon

20042004 Hypernuclear experiment in Hall A, E94-107, carried out20052005 Hypernuclear experiment in Hall A, E94-107, carried out The second generation experiment in Hall C, E01-011, carried out The 3rd generation hypernuclear experiment in Hall C, E05-115, approved

2006-20072006-2007 New electron spectrometer for the 3New electron spectrometer for the 3 rdrd generation experiment, E05-115, generation experiment, E05-115, under constructionunder construction

2008 The E05-115 experiment will be ready for beam in Hall C 2008 The E05-115 experiment will be ready for beam in Hall C ( Nue Nakamura’s Talk )

(e,e’K(e,e’K++) hypernuclear spectroscopy at ) hypernuclear spectroscopy at JLabJLab

Hypernuclear investigationHypernuclear investigation• Mean field aspects of nuclear matterMean field aspects of nuclear matter

– A baryon deep inside a nucleus A baryon deep inside a nucleus distinguishable as a baryon ?distinguishable as a baryon ?

• N interactionN interaction– Flavor SU(3) Flavor SU(3) – mixing or the three-body interactionmixing or the three-body interaction

• New form of nucleiNew form of nuclei

Spectroscopy in the wide mass rangeHigh resolution and High yield rate

Single particle statesSingle particle states

-> -> -nuclear potential-nuclear potential

hyperon in a heavier nucleushyperon in a heavier nucleus

Single-particle orbits in a nucleus

E140a at KEK

Hotchi et al., PRC 64 (2001) 044302 Hasegawa et. al., PRC 53 (1996)1210KEK E140a

• Skyrme HF (Yamamoto)• DDRH (Lenske)• Quark-meson coupling (Saito, Thomas)• ………

Y La PbSi

Hypernuclear Hypernuclear spectroscopyspectroscopy

Reaction spectroscopy -ray spectroscopy

• Resolution > 1.5 MeV with meson beams so far• Applicable to all hypernuclear states• Mass, cross sections, angular distributions, polarization….• Each reaction populates characteristic states

• Resolution as good as a few keV• Applicable to the states below nucleon emission thresholds• Angular distribution, lifetime, branching ratios…• Powerful for spin dependent interaction

Complimentary

Better resolution required Higher yield required

B=0 Hypernuclear production

(+,K ＋ )

Stopped (K-,)

(e,e’K+)(,K ＋ )

(p,K＋ )

　Inflight(K-,)

Hyp

ernu

clea

r C

ross

sec

tio n

Momentum transfer (MeV/c)

mb/sr

nb/sr

b/sr

0 500 1000

JLab

KEK, BNL

BNL, CERN (K-,-)

(+,K+)

(+,K+)

Expansion of hypernuclear chartExpansion of hypernuclear chartby the (e,e’Kby the (e,e’K++) reaction) reaction

Mirror symmetric hypernuclei

A: to be studied by the (e,e’K+) reaction

( ppnp 57(2006) )

K+ detection At very forward angle (~ 0 degrees) Maximum hypernuclear production cross section

e’ detection = tag virtual photon energy and emission angle At extremely forward angles Advantage : Large virtual photon flux Disadvantage : Huge backgrounds from Bremsstrahlung

Kinematics of the (e,e’KKinematics of the (e,e’K++) reaction in ) reaction in Hall C Hall C

pe=0.3GeV/c e’

K+

pK=1.2 GeV/c

Ee=1.8 GeVe- Beam

Target nucleus

E=1.5 GeV21 1.2 1.4 1.6 1.8

σto

tal(

b)

1.0

2.0

Eγ(GeV)

p(,K+) Total cross section

Phys. Lett. B 445, 20 (1998)M. Q. Tran et al.

Kaon Angular Distribution

Angle (deg)

d/d

(

nb/s

r)

Electron Angular Distribution

Angular distributions of Angular distributions of scattered electrons and kaonsscattered electrons and kaons

Sotona

The first (e,e’KThe first (e,e’K++) spectroscopy experiment) spectroscopy experiment(JLab E89-009)(JLab E89-009)

Ee = 1.7,1.8 GeV = E = 1.5 GeVpK = 1.2 GeVe = 0 degreesk = 0-7 degrees

• Electron spectrometer --- Enge split pole• Kaon Spectrometer --- SOS (Short Orbit Spectrometer)• Splitter magnet• 0 degree tagging geometry

SOS

152 nb/sr

1212B spectrum of E89-009B spectrum of E89-009

Ground state doublet

B = 11.4 ± 0.5 MeV

Cross section 140±17(stat) ±18(sys) nb/sr

Motoba’s calculation

Binding energy

Emulsion data B = 11.37 MeV

d/

d

nb

/sr/

0.3

MeV

-B(MeV)

-15 0 5 10 15-5-10

(2+,3+)(1-,2-)

(1-,0-)

(2-,1-)

40

50

60

70

80

90

~ 750 keV(FWHM)

292 hrs0.66 A

T. Miyoshi et al., Phy. Rev. Lett. 90, 232502(2003)

J cross section 1-

2-

What limited the E89-009 What limited the E89-009 experiment ?experiment ?

• Hypernuclear yield rateHypernuclear yield rate– High accidental background rate due to Brems High accidental background rate due to Brems

electrons limited luminosityelectrons limited luminosity

– Kaon solid angle limited detection efficiencyKaon solid angle limited detection efficiency

• Energy resolutionEnergy resolution– The kaon arm limited hypernuclear mass resolutionThe kaon arm limited hypernuclear mass resolution

(1) A high-resolution large-solid-angle kaon spectrometer (HKS)

(2) New experimental configuration “Tilt method”

Maximum momentum 1.2 GeV/cDispersion 4.7 cm/%Momentum resolution 2 x 10-4(FWHM)Solid angle 30 msr w/o splitter 16 msr w splitterMomentum acceptance 12.5 %

The HKS spectrometer system for E01-The HKS spectrometer system for E01-011011

(2) Tilt method for the electron arm

(1) High resolution Kaon Spectrometer (HKS)

K+

e’

E01-011 setup in Hall E01-011 setup in Hall CC

ENGE

HKS

Electron beam

To beam dump

From upstream

Splitter

Electron beam

e’

K+

To beam dump

Kinematical regions of electrons and Kinematical regions of electrons and kaonskaons

12Bgr band

Real data

HKS detectorsHKS detectors

HKS exit

p,K+,+,e+

Time of flight w/ cherenkov Time of flight w/ cherenkov cutcut

p K

p K

tof – K

After cherenkov cut

Tilt methodTilt method

The electron spectrometer (ENGE) vertically tilted by 8 degree

e’8 degree

--- Normal to the dispersive plane of the splitter magnet ---

Higher luminosity Higher hadron rates

Beam currents, singles rates & trigger Beam currents, singles rates & trigger ratesrates

TargetTarget

TargetTargetThicknesThicknes

ss(mg/(mg/cmcm22))

Beam cBeam currenturrent((A)A)

Hadron Hadron singles rate singles rate

(kHz)(kHz)

electron electron singles rate singles rate

(kHz)(kHz)

COIN COIN Trigger Trigger

rate rate (kHz)(kHz)

CHCH22 5mm5mm 1.51.5 3.43.4 590590 0.0880.088

77LiLi 190190 2525 1111 12001200 0.850.85

1212CC 100100 2424 9.59.5 980980 0.2900.290

2828SiSi 6565 1313 7.07.0 1040 1040 0.3770.377

“Tilt method” works !!

E01-011E01-011

Expected yield comparison of E01-011 and Expected yield comparison of E01-011 and E89-009E89-009

ItemItem E01-011E01-011(2(2ndnd generation) generation)

E89-009E89-009(1(1stst

generation)generation)

Gain Gain factorfactor

Virtual photon flux per Virtual photon flux per electron(x10electron(x10-4-4))

0.20.2 44 0.050.05

Target Target thickness(mg/cmthickness(mg/cm22))

100100 2222 4.54.5

Kaon survival rateKaon survival rate 0.350.35 0.40.4 0.880.88

Solid angle of K arm Solid angle of K arm (msr)(msr) 1616 55 3.23.2

Beam current (Beam current (A)A) 2424 0.660.66 3636

Estimated yield Estimated yield ((1212

BBgrgr:counts/h):counts/h)2020

(expected)(expected)

0.90.9(measured(measured

))2323

p(e,e’Kp(e,e’K++))0 0 reactions on CH2 reactions on CH2 targetstargets

12C(e,e’K+) quasi-free

Accidental

E89-009 E01-011

0

450 mg/cm2, 1.5 A, ~ 70 hours8.8 mg/cm2, 0.5 or 1.0 A, 183 hours

1.43 MeV (FWHM)

1.47 MeV (FWHM)

1212CC (e,e’K(e,e’K++))1212B spectraB spectra

Prelim

inary

Hypernuclear excitation spectrum

d/

d

nb

/sr/

0.3

MeV

-B(MeV)

E01-011E89-009

~ 800 keV

Co

un

ts (

0.2

5 M

eV/b

in)

s p292hrs 0.66A

AccidentalsAccidentals

~ 90 hrs 30 A

T. Miyoshi et al., Phy. Rev. Lett. 90, 232502(2003)

Sotona,Motoba 1212C (C (,K,K++))1212CC

B = 10.8 MeV B = -0.2 MeV

12Cg.s yield rate

~20 /hr(1 g/cm2 target)

KEK-E336 SKS

Co

un

ts (

0.2

Me

V/b

in)

Reaction spectra on a Reaction spectra on a 1212C targetC target

Co

un

ts (

0.25

MeV

/bin

)

s p

JLAB – JLAB – HKSHKS

~ 90 hrs ~ 90 hrs w/ 30w/ 30A A

PreliminaryPreliminary

AccidentalsAccidentals

B (MeV)

Core excited

12Bg.s yield rate

~8 /hr (0.1 g/cm2 target)

B(s) = 11.5 MeV B(p) = 1.0 MeV

1212C (e,e’KC (e,e’K++))1212BB

(Preliminary)

Motoba with full (sd)n wave function

AccidentalsAccidentalsCo

un

ts (

0.2

5 M

eV/b

in)

PreliminaryPreliminary

s

p 28Si(e,e’K+)28Al

reaction

B (MeV)

750 keV(FWHM)

B (s)= 18.1 MeV

B (p)= 7.4 MeV

Reaction spectra on a Reaction spectra on a 2828Si targetSi target

( Preliminary )

28Si(,K+)28Si reaction

B (s)= 16.6 MeV

B (p)= 7.0 MeV

KEK E140a SKS

28Si enriched target used

AccidentalsAccidentals

B (MeV)

Co

un

ts (

0.4

MeV

/bin

)

77Li(e,e’KLi(e,e’K++))77He reactionHe reaction

PreliminaryPreliminary 30 hrs 3030 hrs 30AA

s

E. Hiyama, et al., PRC53 2078 (1996)

Sotona

B = 5.4 MeV ( Preliminary )

Reaction spectrum on a Reaction spectrum on a 77Li targetLi target

960 keV (FWHM)

Evolution of (e,e’KEvolution of (e,e’K++) spectroscopy at JLab) spectroscopy at JLab

E89-009E89-009 E94-107E94-107 E01-011E01-011 E05-115E05-115

ConfigurationConfigurationSOS+ENGESOS+ENGE

+Splitter+SplitterHRS+HRSHRS+HRS

+Septum+Septum

HKSHKS+ENG+ENGEE

+Splitter+Splitter

HKSHKS+HES+HES

++New New splittersplitter

Beam intensity (Beam intensity (A) on A) on 1212CC 0.660.66 100100 2424 3030

thickness (mg/cmthickness (mg/cm22)) 2222 100100 100100 100100

Hypernuclear yieldHypernuclear yield

(12(12BBgr :gr : /hr) /hr) 0.90.9 44 8~(20)8~(20) (~40)(~40)

Resolution (keV)Resolution (keV) 750-900750-900700~800700~800(400 keV)(400 keV)

700~800700~800

(3-400)(3-400)(3-400)(3-400)

Beam energy (GeV)Beam energy (GeV) 1.7-1.81.7-1.8 44 1.81.8 2.0 - 2.5*2.0 - 2.5*

ppKK (central : GeV)(central : GeV) 1.21.2 1.91.9 1.21.2 1.21.2

ppee (central: GeV )(central: GeV ) 0.30.3 2.22.2 0.30.3 0.6 – 1.00.6 – 1.0

KK (degree)(degree) 0-70-7 66 1-131-13 1-131-13

e e (degree)(degree) 00 66 4.54.5 2 - 102 - 10

( ) expected

2000 2004-2005 2005 2008?

SummarySummary• Precision hypernuclear spectroscopy by the (e,e’KPrecision hypernuclear spectroscopy by the (e,e’K++) reacti) reacti

on plays an essential role in the investigation of hadronic on plays an essential role in the investigation of hadronic may-body systems that contain “strangeness”.may-body systems that contain “strangeness”.

• The 2nd generation experiment in Hall C, JLab E01-011, The 2nd generation experiment in Hall C, JLab E01-011, has been performed in 2005, installing the new kaon spehas been performed in 2005, installing the new kaon spectrometer (HKS) and adopting so-called “tilt” geometry for ctrometer (HKS) and adopting so-called “tilt” geometry for the electron spectrometer. the electron spectrometer.

• Resolution as good as ~700 keV(FWHM) and yield rate of Resolution as good as ~700 keV(FWHM) and yield rate of 7-8 counts/hr for the 7-8 counts/hr for the 1212

B ground state doublet were realB ground state doublet were realized.ized.

• Preliminary spectra for a Preliminary spectra for a 2828Si target as well as those for Si target as well as those for 11

22C and C and 77Li targets are presented, and compared with calcLi targets are presented, and compared with calculated spectra and (ulated spectra and (++,K,K++) reaction spectra. ) reaction spectra.