Medium heavy hypernuclear spectroscopic experiment JLab E05-115

Medium heavy hypernuclear spectroscopic experiment

JLab E05-115

Tohoku Univ.Toshiyuki Gogami

22nd Indian-summer school (SNP2010) June2009 @ JLab Hall-C

Contents

1. Introduction for E05-1152. E05-115 setup3. Analysis status

22nd Indian-summer school (SNP2010)


1. Introduction for E05-115– (e,e’K+) reaction experiment– Experimental motivation– JLab

2. E05-115 setup3. Analysis status

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


p

n

γ*

ΛK+

e-

e + p e’ + K+ + Λe e

M2HY = (Ee + MT - EK+ - Ee’)2 - ( pe - pK+ - pe’)2

measuretarget nucleus

Feynman diagram

uud

ussud

–pK+

Λ

γ*

Missing mass :

•Binding energy•Cross section

(e,e’K+) reaction

uud

ussud

e e

–pK+

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(pbeam = 1.5 [GeV/c] )

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

Λ’s Spin

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]

E05-115 experimental motivation (1)

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

• Medium heavy (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

E05-115 experimental motivation(2)


s

p d f

Photo- and electro production of medium mass Λ-hypernuclei ,P.Bydzovsky et al. (2008)

FULL(8)1f7/2

1d3/2FULL(4) FULL(4)・・・・・・

sn = 28 p = 24p

d

f

4-

5+

6-

7+

3-

4+

5-

6+

Λ52ΛV

52Cr

or

or

or

or

ls splitting 2l+1∝

ls splitting information can be extracted

JLab CEBAF ( Continuance Electron Beam Accelerator Facility )

• E05-115 experiment1. coincidence experiment (K+ and e-)2. small cross section ( ~100 [nb/sr] )3. energy resolution < 500 [keV] (FWHM)

22nd Indian-summer school (SNP2010)100 [m]

Maximum beam energy 6.0[GeV]

Maximum beam intensity 200[μA/Hall]

Beam emittance ~2 [mm ・ μrad]Beam energy spread <1×10-4

Beam bunch interval ~2[ns] (499[MHz])

• Requirement for accelerator1. high duty factor2. high intensity3. small emittance small ΔE/E

CEBAF can satisfythese requirements

Thomas Jefferson National Accelerator Facility


1. Introduction for E05-1152. E05-115 setup– setup– HES detectors– HKS detectors

3. Analysis status

E05-115 Setup


e + p e’ + K+ + Λ

Δp/p = 2×10-4

Solid angle = 7 [msr]θe = 3° – 14.5° Δp/p = 2×10-4

Solid angle = 8.5 [msr]θK+ = 1° – 14°

pre chicane

Splitter magnet

HES detectors

Picture from downstream view

Reference plane

e’

HES triggerEH1 × EH2

~2 [MHz](8 [μA] on 52Cr)

hit pattern

HES detectors

•Drift chamber : EDC1 , EDC2

•Scintillator wall : EH1 ,EH2

Tracking

Trigger

HKS detectors


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

CP × K~18 [kHz]

(8 [μA] on 52Cr)

HKS detectors

•Drift chamber : KDC1 , KDC2

•Scintillator wall : KTOF1X ,2X,1Y

•Cherenkov detector : Aerogel , Water , Lucite

Tracking

Trigger , TOF

PID

−

π+K+

p

main background π+ , p


1. Introduction for E05-1152. E05-115 setup3. Analysis status– data summary– analysis process– tracking efficiency

Target Hypernucleus Thickness[mg/cm2]

Beam current[μA]

Total charge[C]

Typical rateHES/HKS/COIN [kHz]

7Li 7He 184.0 32.0 4.84 2000 / 7 / 0.9

9Be 9Li 188.1 38.3 5.33 2400 / 9 / 1.6

10B 10Be 56.1 38.7 6.25 1300 / 1 / 0.1

12C 12B 112.5 26.8 5.90 1200 / 5 / 1.0

52Cr 52V 134.0154.0

7.6 0.835.53

2000 / 17 / 1.8

Data summary


Λ

Λ

Λ

Λ

Λ

E05-115 ( 2009 Aug – Nov )

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

(@36μA)

Analysis process


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

x’ , y’ , pat target

Missing mass

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

x’ , y’ , pat target

F2T func. tune

F2T function

F2T function

iteration

iteration

particle ID(select K+)

HKS

HES

450.8 [mg/cm2]2.0 [μA]38 [hours]

E05-115

σ = 2 [MeV/c2](NOT TUNED)

p(e,e’K+)Λ p(e,e’K+)Σ0

Energy calibration (p Λ , Σ0)

Multiplicity in chambers


52Cr targetmean ~ 6 hit

Multiplicity of typical layer

Current tracking code is created for low multiplicity data

This experiment• Multi-hit TDC• Heavier target (52Cr)

High multiplicity

E01-011 at JLab Hall-C (Heaviest target : 28Al)

0 20tracking efficiency ↓

Drift chamber

Tracking efficiencyInput tracks in simulation

(we know everything about these tracks)

data file (hit wire information)

real analyzer


CH2 target

52Cr target Need to improve tracking code

K+

KDC1

KDC2

KTOF1X

Now developing

Current analyzer cannot handle

with high multiplicity data

Summary• E05-115 experiment– 2009 Aug – Nov @JLab Hall C– 7He,9Li,10Be,12B,52V– Spectrometers and Detectors work well

• Tracking code– developing new tracking code for high multiplicity


•optimize parameters ( time, position , cut )•debug

first try to measure Λ-hypernucleiup to A=52 via (e,e’K+)

450.8 [mg/cm2]2.0 [μA]38 [hours]

Preliminary

E05-115

σ = 2 [MeV/c2](NOT TUNED)

Λ Λ ΛΛΛ

End.Thank you


End run party of E05-115 on Mar2010

S.N.Nakamura O.Hashimoto

backup


Multiplicity in chambers


CH2 target 52Cr target

mean ~ 6 hit

Multi-hit TDC

mean ~ 2 hit

CH2 target 52Cr targetmean ~ 1 hitmean ~ 1 hit

106layer

6 layer6

HES

HKS

Origin of multiplicity Multi-hit TDC

e+

∝ Z2

e,+ e-

x [cm]

x’ [r

ad]

Fringe of hall prove

E05-115 experiment motivation

• p-shell(7He,9Li,10Be,12B) charge symmetry

breaking Λ-Σ coupling


• Medium heavy (52V) s-,p-,d-orbit binding energy & cross

section Mass dependence of Λ single

particle energy l ・ s splitting 　∝ 2l+1


絵•charge symmetry•Λ-Σ coupling

Λ and Σ0 mass spectrum


with not tuned F2T function

FWHM ~ 4.7 [MeV/c2]

Number Cross section

Λ 2954 365.8 [nb/sr]

Σ0 772 95.6 [nb/sr]12C QF 13264 1.6 [μb/sr]

Cross section

Fitting

Integral the function

Number of event

HES Tilt methodMain background source

for electron arm1. bremsstrahlung 2. Møller


Angular dependence of electrons(Simulation)

Tilt method

HES was tilted to avoid huge background at forward

HES detectors resolution

EHODO1 to EHODO2TOF resolution 　 σ = 360 [ps]

TOF [ns]

EHO

DO

1 co

unte

r ID

TOF [ns]

Momentum resolution(~2×10-4) Enough resolution

(but can be improved)

EDC1 σ = 250 [μm]

EDC2 σ = 170 [μm]

(e,e’K+) reaction• physical advantage

• large momentum transfer deeply bound• Spin-flip and Spin non-flip• p Λ

• experimental advantage• high quality primary beam• high intensity beamthin targetenergy resolution 　 good

elementary step　 e+p --> e’+Λ+K+

Bothe’ and K+ have forward peak need to be detected at forward

E05-115 spec



Z24136

E89-009 (2000)E01-011 (2005)E05-115 (2009)

difficult (brems. increase with ~Z2 )

12C28Si

52Cr

Λ hypernuclei experiment via (e,e’K+) reaction at JLab Hall-C

1st generation E89-009 (2000 年 )

2nd generationE01-011 (2005 年 )

3rd generationE05-115 (2009 年 )

configuration SPL + Enge + SOSexisting spectrometers

SPL + Enge + HKS +Tilt method

new SPL + HES + HKS + Tilt method

beam energy 1.8 [GeV] 1.8 [GeV] 2.344 [GeV]

data 12ΛB 7

ΛHe,12ΛB,28

ΛAl 7ΛHe,9

ΛLi,10ΛBe,

12ΛB,52

ΛV

resolution(FWHM)

750 [keV] 470 [keV] 400 [keV]

target , thicknessintensity

12C, 22 [mg/cm2] 0.66 [μA]

12C, 100 [mg/cm2]20 [μA]

12C, 112.5 [mg/cm2]27 [μA]

yield(12

ΛB g.s.)0.36 [/hour] 6.4 [/hour] 30 [/hour]

(prediction from QF yield)

S/N (12ΛB g.s.) 0.6 1.6 analyzing

e’ rate 200 [MHz] 1.0 [MHz] 1.7 [MHz]1/200

luminosity ×137

Aug - Nov

E05-115 experimental motivation• p-shell(7He,9Li,10Be,12B)

charge symmetry breaking Λ-Σ coupling


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

energy l ・ s splitting 　∝ 2l+1


FULL(8)1f7/2

1d3/2FULL(4) FULL(4)・・・・・・

sn = 28 p = 24p

d

f

4-

5+

6-

7+

3-

4+

5-

6+

s

p df

Photo- and electro production of medium mass Λ-hypernuclei ,P.Bydzovsky et al. (2008)

Λ Λ Λ Λ

ΛΛ

first time

Medium heavy hypernuclei experiment motivation

precision measurement of medium heavy hypernuclei　　　 52Cr(e,e’K+)52

ΛV• s-,p-,d-orbit binding energy & cross section• Mass dependence of Λ single particle energy• l ・ s splitting 　∝ 2l+1

3rd generation E05-115(2009)

2nd generation E01-011(2005)

1st generation E89-009(2000)

Λ hypernuclei experiment via (e,e’K+)

E05-115 exp. schematic diagram

target nucleus

e + p e’ + Λ + K+

e + p e’ + Σ0 + K+

Missing mass

given

measure

can be derived

beam 2 [ μA ]

+Tilt method

Optimization tilt angle by Simulation

• rate of electrons associated with hypernuclei S• rate of electrons from Møller scattering NMφller

• rate of electrons from bremsstrahlung NBrems

Figure of Merit (FoM)

6.5o

Coincidence time Tcoin

Coincidence time [ns]

2 [ns] beam bunch structure

accidental event

Λ + accidental event

K+ 同定後

Accidental Accidentalcoincidence time

Typical rate for each target

beam momentum and recoil momentum

VP and brems. flux

Ei=2.344[GeV],ω=1.5[GeV]

central momentum• P(γ,K+)Λ で生成断面積が最も大き

くなるのは仮想光子のエネルギー ω=1.5[GeV] のときである。ω=1.5[GeV] とする為には、

Ee’=Ee-ω

=2.344-1.5 =0.844[GeV]

この散乱電子のエネルギー領域では、

E2e’ 　= m2

e’+p2e’ ~= p2

e’

とみなすことができる。

この為、 HES の中心運動量は0.844[GeV/c] をとることにした。

Trigger• HKS side

– TOF trigger(CP)i=(KTOF1X)i×(KTOF1Y)×(KTOF2X)i

– WC and AC veto trigger(K)i=(WC)i×(AC)i

– (CP)i and (K)i coincidence trigger

(HKS)i=(CP)i×(K)i

– HKS トリガーHKStrigger=Σ(HKS)i

• (WC)i=(WC1)i×(WC2)i

• (AC)i=2/3{(AC1)i×(AC2)i×(AC3)i}

• (AC1)i=(AC1)iTOP+(AC1)i

BOT


BOT


BOT

• HES side• HEStrigger=(EHODO1)×(EHODO2)

• coincidence trigger• COINtrigger=(HKStrigger)×(HEStrigger)

i:Group ID×:AND＋ :OR

Number of photon


aerogel water

lucite

Normalized NPE (hwatnkn1,2)

easier to select K+ than before

2 type of WCneed two cuts

Yield estimation with simulation

Target(100mg/cm2) 2nd generation exp.E01-011

3rd generation exp.E05-115

HKS+Enge+splitterTilt method

Ee=1.851 [GeV]

HKS+HES+new splitterTilt method

Ee=2.344 [GeV]

7Li 21.5 /hour 64 /hour10B 12 /hour 44 /hour12C 12 /hour 37 /hour

52Cr - 9 /hour

×3~4

beam intensity : 30 [μA]target thickness : 100[mg/cm2]cross section : 100[nb/sr]

real data

≈expected value from real QF data 30 [/hour]

Angler acceptance

yield UP

2nd generation exp. E01-011

3rd generation exp.E05-115

incident beam energy1.851 2.344 [GeV]

•HES has large angler acceptance

background gather to forwardaccept more forward angle

Solid angle &Momentum matching


HKS

HES

~ 7.5 [msr]

~ 5.0 [msr] 52ΛV g.s.

HES detectors

Picture from downstream view

Reference plane

configuration

drift chamber( EDC1 )

xx’uu’(+30deg)xx’vv’(-30deg)xx’ 100 ×12 ×30 cm ,

drift chamber( EDC2 )

uu’(+60deg)xx’vv’(-60deg) 120 × 30 × 2 cm ,

scintillator ( EH1,2 )

29 – segment , H6612 , EJ-230117 × 30 × 1 cm ,

scintillator( EH3 )

1 – segment , H7195 , RP-408127 × 3.8 × 3 cm

e’

HES triggerEH1 × EH2

~2.0 [MHz](8.0 [μA] on 52Cr)

hit pattern

Tracking

Trigger Time correction

σ = 250 [μm]

σ = 170 [μm]

σ = 350 [ps]

HKS detectors


Tracking

main background π+ , p

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

CP × K

~18.0[kHz](8 [μA] on 52Cr)

σ = 0.03β

TOF

Particle ID p

K+π+

β (resolution σ = 0.03)

WC

NPE

1 +

2

σ = 170 [μm]

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

5.532.0E+3

(4.7 μb/sr)~25

(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

HES HKS multiplicity in chambers

CH2 target 52Cr target

HKS chambers

HES chambers What make this difference ?

Origin of high multiplicity in chambers

• high multiplicity の主犯52Cr 自身は悪くないこれをなくせばさらに重くてもいける (tracking code , hard ware)

∝ ~Z2

e+

e- , e+

Tracking and multi-hit


CH252Cr

CH2 target 52Cr targetmean ~ 2 hit mean ~ 6 hit

Can our analyzer deal with this efficiently ?

Top view of KDC1track

hit wire center

drift distance+

KDC1

KDC1

KDC2

track

Tracking efficiencyInput tracks in simulation

(we know everything about these track)

data file (hit wire information)

real analyzer


CH2 target

52Cr target Need to improve tracking code

K+

KDC1

KDC2

KTOF1X

Now developing

Current analyzer cannot handle

with high rate data

Tracking and multi-hit


CH2 target 52Cr targetmean ~ 2 hit mean ~ 6 hit

Multi-hit TDC

e+

∝ Z2

e,+ e-

x [cm]

x’ [r

ad]

entrance of hall prove


Spectroscopy of Λ hypernuclei , O.Hashimoto , H.Tamura , Progress in Particle and Nuclear Physics 57 (2006) 564-653

Medium heavy hypernuclear spectroscopic experiment JLab E05-115

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