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 University Toshiyuki Gogami for the HES-HKS collaborations JLab Hall-C (2009) Contents 1.Introduction 2.Experimental setup 3.K + Λ electro-production 4.Summary 2012/9/14JPS meeting in Kyoto, Toshi Gogami1
Spectroscopic experiment by (e,e’K + ) reaction p n γ*γ* Λ K+K+ e-e- e + p ➝ e’ + K + + Λ ee target nucleus Feynman diagram u u d u s s u d – p K+K+ Λ γ*γ* ~ 1990’s (K -,π - ), (π +,K + ) reactions Energy resolution ~ a few MeV n Λ e’-Spectrometer K + -Spectrometer p e’ p K+ Missing Mass H HY ~ (e,e’K + ) reaction Energy resolution ~500keV p Λ 2012/9/14JPS meeting in Kyoto, Toshi Gogami
E experimental motivation Light Λ hyprenuclei ( 7 He, 9 Li, 10 Be, 12 B) Charge symmetry breaking Λ-Σ coupling Medium heavy Λ hyprenuclei ( 52 V) s-,p-,d-,f-orbit binding energy & cross section Mass dependence of Λ single particle energy l ・ s splitting ∝ 2l Aug – JLab Hall-C (e,e’K + ) reaction Target : 7 Li, 9 Be, 10 B, 12 C, 52 Cr ΛΛ ΛΛ Λ First try B Λ [MeV] It is difficult experimentally. “ b.g. electron due to brems. ∝ ~Z 2 “ A = 52 Λ, Σ 0 Energy scale calibration Elementary process 2012/9/14JPS meeting in Kyoto, Toshi Gogami3
Electro-production of K + Λ JLab E experiment by the (e,e’K + ) reaction Small Q 2 ( ~0.01 [GeV/c] 2 ) almost real photon Real photon 2012/9/14JPS meeting in Kyoto, Toshi Gogami4
An importance of measurement of K + Λ production at forward angles At forward angles – Data show lack of consistency – We can access θ K cm ~ 15 deg P.Bydzovsky and T.Mart, Phys. Rev. C 76, (2007) 2012/9/14JPS meeting in Kyoto, Toshi Gogami5
JLab E experimental setup Δp/p ~ 2×10 -4 Solid angle ~ 7 [msr] θ lab ~ 3 – 12 [deg] Δp/p ~ 2×10 -4 Solid angle ~ 11 [msr] θ lab ~ 2 – 12 [deg] e + p → e’ + Λ + K + 7 Li, 9 Be, 10 B, 12 C, 52 Cr CH 2, H 2 O 2012/9/14JPS meeting in Kyoto, Toshi Gogami6
Polyethylene(CH 2 ) target High intensity beam ~2.0 μA / (1×3 mm 2 ) Hydrogen was escaping from the target Before After 2012/9/14JPS meeting in Kyoto, Toshi Gogami7
Λ, Σ 0 from CH 2 target JPS meeting in Kyoto, Toshi Gogami 2012/9/14 Preliminary 8
Λ, Σ 0 from CH 2 target JPS meeting in Kyoto, Toshi Gogami 2012/9/14 Preliminary 9 p(e,e’K + )Λ ~1.8MeV (FWHM) Δm = 19 ± 17 keV/c 2 p(e,e’K + )Σ 0 ~1.8MeV (FWHM) Δm = 73 ± 47 keV/c 2 JLab E CH 2, ~ 450 [mg/cm 2 ] ~ 2.0 [μA] ~ 38 [hours]
Preliminary results of p(γ*,K + )Λ 2012/9/14JPS meeting in Kyoto, Toshi Gogami10 Preliminary JLab E (HES-HKS) 192±6±89 [ nb / sr ] SAPHIR : K.H.Glander et al., Eur. Phys. J. A 19, (2004) CLAS : R.Bradford et al., Phys. Rev. C 73, (2006) ( JLab E05-115, Q 2 ~ 0.01 [GeV/c] 2 )
Comparison with data of JLab Hall-A Large longitudinal term contributions? p(γ*,K + )Λ ~ JLab E (HES-HKS) W ~ 1.9 GeV Q 2 ~ 0.01 [GeV/c] 2 p(γ*,K + )Λ ~ JLab E (HES-HKS) W ~ 1.9 GeV Q 2 ~ 0.01 [GeV/c] 2 Preliminary p(γ*,K + )Λ ~ JLab E W ~ 2.2 GeV Q 2 ~ 0.07 [GeV/c] 2 p(γ*,K + )Λ ~ JLab E W ~ 2.2 GeV Q 2 ~ 0.07 [GeV/c] 2 SAPHIR : K.H.Glander et al., Eur. Phys. J. A 19, (2004) CLAS : R.Bradford et al., Phys. Rev. C 73, (2006) JLab E : P.Markoviz et al., Proceedings of SENDAI08 (2009) 2012/9/14JPS meeting in Kyoto, Toshi Gogami11
Summary JLab E (HES-HKS) was performed in JLab Hall-C in 2009 – 7 Λ He, 9 Λ Li, 10 Λ Be, 12 Λ B, 52 Λ Cr, Λ, Σ 0 High statistical data of p(γ*,K + )Λ – cosθ CM ~0.97, W ~1.9 GeV, Q 2 ~0.01 [GeV/c] 2 192±6±89 [ nb / sr ] Further studies – Mainz MAMI-C Interference term (14aSC-2 : 塚田 ) – JLab New proposal 2012/9/14JPS meeting in Kyoto, Toshi Gogami12
HES-HKS Collaborations /9/14JPS meeting in Kyoto, Toshi Gogami
Thank you for your attention Prof. S.N.Nakamura Prof. O.Hashimoto End run party of E (Mar2010) 2012/9/14JPS meeting in Kyoto, Toshi Gogami14
backup 2012/9/14JPS meeting in Kyoto, Toshi Gogami15
Preliminary results of p(γ*,K + )Σ 0 SAPHIR : K.H.Glander, Eur. Phys. J. A 19, (2004) CLAS : R.Bradford, Phys. Rev. C 73, (2006) JLab E (HES-HKS) 62±6±26 [ nb / sr ] ( JLab E05-115, Q 2 ~ 0.01 [GeV/c] 2 ) Preliminary 2012/9/14JPS meeting in Kyoto, Toshi Gogami16
Detectors & Trigger K + p, π + e-e- Drift chambers TOF walls (Plastic scintillators) Cherenkov detectors Aerogel (n=1.05) Water (n=1.33) HES HKS 2012/9/14JPS meeting in Kyoto, Toshi Gogami17
Detectors & Trigger K + p, π + e-e- Drift chambers TOF walls (Plastic scintillators) Cherenkov detectors Aerogel (n=1.05) Water (n=1.33) HES HKS HKS trigger (TOF1x2x3) x Chrenkov ~10 kHz HKS trigger (TOF1x2x3) x Chrenkov ~10 kHz HES trigger (TOF1x2) ~2000 kHz HES trigger (TOF1x2) ~2000 kHz Coincidence trigger HES x HKS < 2 kHz Coincidence trigger HES x HKS < 2 kHz 2012/9/14JPS meeting in Kyoto, Toshi Gogami18
Analysis process JPS meeting in Kyoto, Toshi Gogami raw datadecodingtrackingx, x’, y, y’ at Reference plane x’, y’, p at target Missing mass raw datadecodingtrackingx, x’, y, y’ at Reference plane x’, y’, p at target F2T func. tune F2T function iteration particle ID (select K + ) HKS HES Energy calibration (p Λ, Σ 0 ) 2012/9/1419
Analysis process JPS meeting in Kyoto, Toshi Gogami raw datadecodingtrackingx, x’, y, y’ at Reference plane x’, y’, p at target Missing mass raw datadecodingtrackingx, x’, y, y’ at Reference plane x’, y’, p at target F2T func. tune F2T function iteration particle ID (select K + ) HKS HES 2012/9/1420
HKS detectors JPS meeting in Kyoto, Toshi Gogami 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 52 Cr) − π+π+ K+K+ p σ ≈ 250 [μm] TOF σ ≈ 170 [ps] 2012/9/1421
JPS meeting in Kyoto, Toshi Gogami HES Detectors Drift chambers - EDC1, EDC2 - TOF walls - EH1, EH2 - (Plastic scintillators) HES D magnet HES trigger EH1 × EH2 ~2 [MHz] (8 [μA] on 52 Cr) e Time Of Flight σ ~ 300 [ps] 2012/9/1422
Missing mass spectrum JLab E CH 2, ~ 450 [mg/cm 2 ] ~ 2.0 [μA] ~ 38 [hours] Accidental Coincidence Quasi free Λ from 12 C 2012/9/14JPS meeting in Kyoto, Toshi Gogami23 JLab E CH 2, ~ 450 [mg/cm 2 ] ~ 2.0 [μA] ~ 38 [hours] p(e,e’K + )Λ ~1.8MeV (FWHM) Δm = 19 ± 17 keV/c 2 p(e,e’K + )Σ 0 ~1.8MeV (FWHM) Δm = 73 ± 47 keV/c 2
2012/9/14JPS meeting in Kyoto, Toshi Gogami24 e-e- e’e’ K+K+
Considered efficiencies Simulation 2012/9/14JPS meeting in Kyoto, Toshi Gogami25
K + production at small angles electroproduction SL: 0.41 = ( = 0.7 ) a steep Q 2 dependence ? P. Bydzovsky’s presentation at ECT* 2011 ( *,K + ) JLab Hall-A E W=1.9 GeV Q 2 =0.01 (GeV/c) /9/14JPS meeting in Kyoto, Toshi Gogami 26
Electro-production of K + Λ JLab E experiment by the (e,e’K + ) reaction Small Q 2 ( ~0.01 [GeV/c] 2 ) almost real photon, 2012/9/14JPS meeting in Kyoto, Toshi Gogami27
Estimation of the number of events by the fitting ~Lambda~ Number : Mean : [keV/c2] ( Delta Mean : [keV/c2] ) Width : [keV/c2] ~Sigma~ Number : Mean : [keV/c2] ( Delta Mean : [keV/c2] ) Width : [keV/c2] peakbackground B : Half width at half maximum C : Center value 2012/9/14JPS meeting in Kyoto, Toshi Gogami28
Cut conditions to make the missing mass Cut conditions – 1.0 > NWC 1+2 – 5.0 < AC – -1.0 < coincidence time < 1.0 – 0.08 < Mass square < 0.44 – HKS tracking chi-square < – HES tracking chi-square < /9/14JPS meeting in Kyoto, Toshi Gogami29
K + survival Ratio after the mass square cut (CH 2 ) If applied these two cut at the same time (Suv. Ratio) total = (Suv. Ratio1) + (Suv. Ratio2) – 1.0 Suv. ratio1 Suv. ratio2 Cut 2 Cut 1 K + survival ratio 2012/9/14JPS meeting in Kyoto, Toshi Gogami30
K + survival ratio after AC cut (CH 2 ) (accut,wccut) = (5,-0.1) pi suv. ratio: K suv. ratio: p suv. ratio: (accut,wccut) = (10,-0.1) pi suv. ratio: K suv. ratio: p suv. ratio: (accut,wccut) = (15,-0.1) pi suv. ratio: K suv. ratio: p suv. ratio: Stricter cut of AC NPE looser cut of AC NPE π+π+ K+K+ p π+π+ K+K+ p 2012/9/14JPS meeting in Kyoto, Toshi Gogami31
K + survival ratio after WC cut (CH 2 ) (accut,wccut) = (2000,1.1) pi suv. ratio: K suv. ratio: p suv. ratio: (accut,wccut) = (2000,1) pi suv. ratio: K suv. ratio: p suv. ratio: (accut,wccut) = (2000,0.9) pi suv. ratio: K suv. ratio: p suv. ratio: Stricter cut of WC NPE looser cut of WC NPE π+π+ K+K+ p π+π+ K+K+ p 2012/9/14JPS meeting in Kyoto, Toshi Gogami32
Tracking efficiencies ~~~~ HKS~~~~~~~ ch2 : Tracking Efficiency : ( %) h2o : Tracking Efficiency : ( %) li : Tracking Efficiency : ( %) be : Tracking Efficiency : ( %) b : Tracking Efficiency : ( %) c : Tracking Efficiency : ( %) cr1 : Tracking Efficiency : ( %) cr2 : Tracking Efficiency : ( % ) ~~~~ HES~~~~~~~ ch2 : Tracking Efficiency : ( %) h2o : Tracking Efficiency : ( %) li : Tracking Efficiency : ( %) be : Tracking Efficiency : ( %) b : Tracking Efficiency : ( %) c : Tracking Efficiency : ( %) cr1 : Tracking Efficiency : ( %) cr2 : Tracking Efficiency : ( %) 1 ….!? Need to check tracking code 2012/9/14JPS meeting in Kyoto, Toshi Gogami33
HKS efficiency ε HKS = – AC : ( ) – WC : ( ) – Tracking : (+0.001, ) – M2 : 0.96 – Ctime : 0.99 – f decay : (± 0.006) – f burn : /9/14JPS meeting in Kyoto, Toshi Gogami34
Definition of the cross section SIMULATION 2012/9/14JPS meeting in Kyoto, Toshi Gogami35
Theta and Momenta of the scattered electrons 2012/9/14JPS meeting in Kyoto, Toshi Gogami36
Angular acceptance cut θ e’ > 0.05 rad 2012/9/14JPS meeting in Kyoto, Toshi Gogami37
2012/9/14JPS meeting in Kyoto, Toshi Gogami38
Back ground estimation Optimal scaling factor 1.08 Black + (Green × scaling factor) = Blue Scaling factor : /9/14JPS meeting in Kyoto, Toshi Gogami39
Current missing mass spectrum JLab E CH 2, ~ 450 [mg/cm 2 ] ~ 2.0 [μA] ~ 38 [hours] 2012/9/14JPS meeting in Kyoto, Toshi Gogami40
Current missing mass spectrum JLab E CH 2, ~ 450 [mg/cm 2 ] ~ 2.0 [μA] ~ 38 [hours] Accidental Coincidence Quasi free Λ from 12 C 2012/9/14JPS meeting in Kyoto, Toshi Gogami41
The number of events of Λ and Σ ± 125 (Integrated : -5 – 9 MeV/c 2 ) 1579 ± 94 (Integrated : 72 – 86 MeV/c 2 ) Λ Σ0Σ0 JLab E CH 2, ~ 450 [mg/cm 2 ] ~ 2.0 [μA] ~ 38 [hours] 2012/9/14JPS meeting in Kyoto, Toshi Gogami42
Momentum acceptance cut (Σ 0 ) HES momentum region – – – Λ V g.s. ~8.5 msr 2012/9/14JPS meeting in Kyoto, Toshi Gogami43
Momentum acceptance cut (Λ) HES momentum region – – – Λ V g.s. ~8.5 msr 2012/9/14JPS meeting in Kyoto, Toshi Gogami44
Momentum acceptance cut ~8.5 msr HES momentum region – GeV/c – GeV/c – GeV/c Λ Σ0Σ0 2012/9/14JPS meeting in Kyoto, Toshi Gogami45
Momentum acceptance cut ~8.5 msr HES momentum region [ GeV/c ] ~ ( < W [ GeV ] < ) Λ Σ0Σ0 2012/9/14JPS meeting in Kyoto, Toshi Gogami46
Data Summary JLab E (2009/June – 2009/Nov) JPS meeting in Kyoto, Toshi Gogami472012/9/14
Singles rate summary Up to ~30 [MHz] Up to ~15 [MHz] HES HKS HKS trigger ~ 10[kHz] HES trigger ~ a few[MHz] JPS meeting in Kyoto, Toshi Gogami482012/9/14
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’u u’ x x’ v v’ u u’u u’ x x’ KDC1 KDC2 particle JPS meeting in Kyoto, Toshi Gogami492012/9/14
KTOF multiplicity ~2.7~1.8 ~6.5 ~3.8 CH 2, Cr, Multiplicity of KDC are not only high but also TOF counters are! (for heavy target ) JPS meeting in Kyoto, Toshi Gogami502012/9/14
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 9 Be, 38.4 [μA] Events on HKS optics Overhead view Side view Β ≈ 1 e -, e + JPS meeting in Kyoto, Toshi Gogami512012/9/14
B.G. mix rate (real data) a b * hks ntulpe JPS meeting in Kyoto, Toshi Gogami522012/9/14
e + simulation SIMULATION To see 1.Number of event 2.Angle & momentum of e + generated in target To see 1.Number of event 2.Angle & momentum of e + generated in target JPS meeting in Kyoto, Toshi Gogami532012/9/14
Target thickness dependence (Simulation) H2OH2O 52 Cr 9 Be 12 C CH 2 10 B 7 Li Consistent with B.G. mix rate ! SIMULATION JPS meeting in Kyoto, Toshi Gogami542012/9/14
Angle and momentum distribution of positrons HKS cannot accept positrons directly ! Generate these event in HKS GEANT (Next page) SIMULATION JPS meeting in Kyoto, Toshi Gogami552012/9/14
e, e + background in GEANT simulation Vacuum chamber (sus304) NMR port (sus304) KDC1KDC2 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 JPS meeting in Kyoto, Toshi Gogami562012/9/14
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 JPS meeting in Kyoto, Toshi Gogami572012/9/14
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’u u’ x x’ v v’ u u’u u’ x x’ KDC1 KDC2 particle JPS meeting in Kyoto, Toshi Gogami582012/9/14
Spectroscopic experiment by (e,e’K + ) reaction p n γ*γ* Λ K+K+ e-e- e + p ➝ e’ + K + + Λ ee target nucleus Feynman diagram u u d u s s u d – p K+K+ Λ γ*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 p e’ p K+ Missing Mass H HY JPS meeting in Kyoto, Toshi Gogami592012/9/14
JLab E experimental setup 2× [msr] 3 – 12 [deg] 2× [msr] 2 – 12 [deg] e + p → e’ + Λ + K + 7 Li, 9 Be, 10 B, 12 C, 52 Cr (e,e’K + ) experiment 1.Coincidence experiment (K + and e - ) 2.Small cross section ( ~100 [nb/sr] ) 1/ Energy resolution Sub MeV (FWHM) Primary beam High intensity Thin target (~100 [mg/cm 2 ]) High quality JPS meeting in Kyoto, Toshi Gogami602012/9/14
JPS meeting in Kyoto, Toshi Gogami 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/ Energy resolution sub MeV (FWHM) 100 [m] Requirements for accelerator 1.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 /9/14
Coincidence time vs. Mass square JPS meeting in Kyoto, Toshi Gogami622012/9/14
Cherenkov cut JPS meeting in Kyoto, Toshi Gogami632012/9/14
Cherenkov light JPS meeting in Kyoto, Toshi Gogami642012/9/14
HES の構成 ED1 Max. Field Gradient7.8[T/m] Max. Current800[A] Total magnet weight2.8[ton] EQ2 Max. Field Gradient5.0[T/m] Max. Current800[A] Total magnet weight3.1[ton] ED Max. Field1.65[T] Max. Current1065[A] Total magnet weight36.4[ton] 2012/9/14JPS meeting in Kyoto, Toshi Gogami65
Λ hypernuclear spectroscopy Updated from: O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys. 57 (2006) V /9/14JPS meeting in Kyoto, Toshi Gogami
(e,e’K + ) experiment in JLab st generation exp. JLab E e’-spectrometer + K + -spectrometer 12 Λ B ~ 750 [keV] (FWHM) nd generation exp. JLab E e’-spec. Optimized configuration + HKS(K + ) 7 Λ He, 12 Λ B, 28 Λ Al ~ 600 [keV] (FWHM) rd generation exp. JLab E HES(e’) Optimized configuration + HKS(K + ) 7 Λ He, 9 Λ Li, 10 Λ Be, 12 Λ B, 52 Λ V ≤ 500 [keV] (FWHM) Proof of feasibility Establish exp. method Up to Medium heavy 2004 JLab E (K +, e + )-spectrometers + septum 9 Λ Li, 12 Λ B, 16 Λ N ~ 670 [keV] (FWHM) Hall-C Hall-A Avoid huge background at very forward angle JPS meeting in Kyoto, Toshi Gogami672012/9/14
Analysis status of E p(e,e’K + )Λ,Σ 0 HES-HKS basic system works well ~40 hours (5 shifts) JLab E p(e,e’K + )Λ,Σ 0 Very preliminary Analysis is in progress 1.Energy (mass) calibration 2.Developing new code for high multiplicity data Analysis is in progress 1.Energy (mass) calibration 2.Developing new code for high multiplicity data E.M background ∝ ~Z 2 Λ and Σ 0 can be seen at the same time rd generation exp. JLab E HES(e’) Optimized configuration + HKS(K + ) 7 Λ He, 9 Λ Li, 10 Λ Be, 12 Λ B, 52 Λ V ≤ 500 [keV] (FWHM) Up to Medium heavy Hall-C JPS meeting in Kyoto, Toshi Gogami682012/9/14
Experimental data of A=7 system Old 7 Λ He data ( M.Juric, NPB 52, 1973 ) -B [MeV] 0.03 0.2 MeV from α n n JLab E Li(e,e’K + ) 7 Λ He 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 JPS meeting in Kyoto, Toshi Gogami692012/9/14
JPS meeting in Kyoto, Toshi Gogami Theoretical calculation of A=7 system Four-body cluster model for T=1 iso-triplet hypernuclei (E.Hiyama et al., NPC 80, 2009) α + Λ + N + N Old 7 Λ He data ( M.Juric, NPB 52, 1973 ) -B [MeV] 0.03 0.2 MeV from α n n JLab E Li(e,e’K + ) 7 Λ He Compare to theoretical calculation Preliminary /9/14
Theoretical calculation of A=7 system -B (MeV) 0.03 0.2 MeV from α n n Four-body cluster model for T=1 iso-triplet hypernuclei (E.Hiyama et al., PRC 80, 2009) α + Λ + N + N JLab E Li(e,e’K + ) 7 Λ He CSB interaction is determined to reproduce B Λ of 4 Λ H and 4 Λ He. Will be talked by E.Hiyama in Plenary 6 session(8/24) Decay pion spectroscopy Preliminary /9/14JPS meeting in Kyoto, Toshi Gogami
Summary (e,e’K + ) spectroscopic exp. in JLab – E (2000,Hall-C) 12 Λ B – E (2004,Hall-A) 9 Λ Li, 12 Λ B, 16 Λ N – E (2005,Hall-C) 7 Λ He, 12 Λ B, 28 Λ Al – E (2009,Hall-C) 7 Λ He, 9 Λ Li, 10 Λ Be, 12 Λ B, 52 Λ V Precision light Λ hypernuclear spectroscopy – 7 Λ He (preliminary result by E01-011) – 10 Λ Be (analyzing) Analysis stage Final analysis stage ΛN charge symmetry breaking JPS meeting in Kyoto, Toshi Gogami722012/9/14
JPS meeting in Kyoto, Toshi Gogami73 End Thank you very much Experimental hall-C, JLab (2009) 2012/9/14
(e,e’K + ) reaction u u d u s s u d ee – p K+K+ Λ γ*γ* u d d d u u s s d u ––π+π+ Λ n u s d d u u d s d u – K-K- Λ n – π-π- e + p ➝ e + K + + Λπ + + n ➝ K + + Λ K+K+ K - + n ➝ π - + Λ (π +, K + )(K -, π - )(e,e’K + ) Momentum transfer (Typical ) ~300 [MeV/c] ~90 [MeV/c] Λ’s Spin At forward angle Λ’s from proton neutron flip ≈ non-flip non-flip Beam primary secondary Target Thin (~100 mg/cm 2 ) (Isotopically enriched) Thick(> a few [g/cm 2 ] ) Reaction Λ can be bounded in deeper orbit Spin dependent structure Mirror lambda hypernuclei High quality, high intensity Fine structure Energy resolution (FWHM) ≤ 500 [keV]1 – 3 [MeV] JPS meeting in Kyoto, Toshi Gogami742012/9/14
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 52 Cr) − π+π+ K+K+ p σ ≈ 200 [μm] TOF σ ≈ 170 [ps] JPS meeting in Kyoto, Toshi Gogami752012/9/14
JPS meeting in Kyoto, Toshi Gogami HES Detectors Drift chambers - EDC1, EDC2 - TOF walls - EH1, EH2 - (Plastic scintillators) HES D magnet HES trigger EH1 × EH2 ~2 [MHz] (8 [μA] on 52 Cr) e Time Of Flight σ ~ 300 [ps] /9/14
Targethypernucleusthickness [mg/cm 2 ] beam current[μA] total charge[C] number of QF Λ (online) expected number of g.s. 7 Li 7 He E+4 (1.0 μb/sr) ~1000 (20 nb/sr) 9 Be 9 Li E+4 (1.2 μb/sr) ~200 (5 nb/sr) 10 B 10 Be E+4 (1.3 μb/sr) ~800 (20 nb/sr) 12 C 12 B E+4 (1.5 μb/sr) ~2000 (100 nb/sr) 52 Cr 52 V E+3 (4.7 μb/sr) ~100 (70 nb/sr) Data summary JPS meeting in Kyoto, Toshi Gogami Λ Λ Λ Λ Λ E ( 2009 Aug – Nov ) measured assumption Targethypernucleusthickness [mg/cm 2 ] beam current[μA] total charge[C] CH 2 Λ, Σ H2OH2OΛ, Σ 0 ~ Physics Data Calibration Data /9/14
E JPS meeting in Kyoto, Toshi Gogami782012/9/14
and spectra (CH2 target) c.f. E89-009, 183 hours (8.8 mg/cm 2, 0.5 or 1.0 uA) T. Miyoshi et al., Phy. Rev. Lett. 90, (2003) Better resolution and statistics ~ 3.5 MeV (FWHM) 1.9 MeV (FWHM) 2.3 MeV (FWHM) E ~70 hours (450 mg/cm 2, 1.5 uA) JPS meeting in Kyoto, Toshi Gogami792012/9/14
Background subtraction Accidental background : polynomial function JPS meeting in Kyoto, Toshi Gogami802012/9/14
GEANT4 12 C 100 mg/cm 2 Effect of simple gaussian fit: = +20 keV count difference : -30 % JPS meeting in Kyoto, Toshi Gogami812012/9/14
12 C(e,e’K + ) 12 B Resolution : ~470 keV (FWHM) for g.s. Data taking : ~30 hours w/ 30 A Fitting Result #1 #2 Two major peaks #1 : [(p 3/2 ) -1 p,(s 1/2 ) ] #2 : [(p 3/2 ) -1 p,(p 3/2,p 1/2 ) ] (126) (130) JPS meeting in Kyoto, Toshi Gogami822012/9/14
#1 #2 12 C(e,e’K + ) 12 B, 12 C( +,K + ) 12 C JPS meeting in Kyoto, Toshi Gogami832012/9/14
12 C(e,e’K + ) 12 B #1 #2 JPS meeting in Kyoto, Toshi Gogami842012/9/14
12 C(e,e’K + ) 12 B Red : calculation with SLA Green : calculation with KMAID Theory by Sotona et. al. (1.3 < E < 1.6 GeV, 1 < K < 13 deg.) Result #1 JJ Ex [MeV] Cross section [nb/sr] SLAKMAID #2 IDEx [MeV] Cross section [nb/sr] Cross section (Calc., SLA) [nb/sr] #1097±3.9 (stat.) +29,-22 (sys.) 85.4 ( ) #211.18±0.01 (stat.) ±0.10 (sys.) 100±3.8 (stat.) +30, -30 (sys.) ( ) (126) (130) JPS meeting in Kyoto, Toshi Gogami852012/9/14
12 C(e,e’K + ) 12 B Two major peaks ; #1:[(p 3/2 ) -1 p,(s 1/2 ) ], #2:[(p 3/2 ) -1 p,(p 3/2,p 1/2 ) ] – Consistent -B with previous exp. – Different width for g.s. with E data – Ex and cross sections : agree with shell model calculation Best resolution of 470 keV (FWHM) for g.s. JPS meeting in Kyoto, Toshi Gogami862012/9/14
28 Si(e,e’K + ) 28 Al Resolution : ~450 keV (FWHM) for g.s. Data taking : ~30 hours w/ 30 A #1 #2 #3 Fitting Result Three major peaks #1 : [(d 5/2 ) -1 p,(s 1/2 ) ] #2 : [(d 5/2 ) -1 p,(p 3/2,p 1/2 ) ] #3 : [(d 5/2 ) -1 p,(d 5/2,d 3/2 ) ] First sd-shell hypernuclear spectroscopy by (e,e’K + ) (78) (122) (77) JPS meeting in Kyoto, Toshi Gogami872012/9/14
Shell model calculation Full space (0d 5/2 0d 3/2 1s 1/2 ) pn 11,12 DWIA YNG interaction JPS meeting in Kyoto, Toshi Gogami882012/9/14
#1 #2 #3 28 Si(e,e’K + ) 28 Al, 28 Si( +,K + ) 28 Si JPS meeting in Kyoto, Toshi Gogami892012/9/14
28 Si(e,e’K + ) 28 Al Theory by Sotona et. al. (1.3 < E < 1.6 GeV, 1 < K < 13 deg.) #1 JJ Ex [MeV] Cross section [nb/sr] SLAKMAID 2 +, #2 #3 IDEx [MeV] Cross section [nb/sr]Cross section (Calc. SLA) )[nb/sr] #1060±5.0 (stat.) +27, -18 (sys.) 92.1 ( ) #210.98±0.02 (stat.) ±0.30 (sys.) 94±6.0 (stat.) +43, -28 (sys.) ( ) #319.30±0.03 (stat.) ±0.30 (sys.) 59±6.7 (stat.) +55, -18(sys.) ( ) Red : calculation with SLA Green : calculation with KMAID Result (78) (122) (77) JPS meeting in Kyoto, Toshi Gogami902012/9/14
28 Si(e,e’K + ) 28 Al First sd-shell hypernuclear spectroscopy by (e,e’K + ) Three major peaks ; #1:[(d 5/2 ) -1 p,(s 1/2 ) ], #2:[(d 5/2 ) -1 p,(p 3/2,p 1/2 ) ] #3:[(d 5/2 ) -1 p,(d 5/2,d 3/2 ) ] – Deeper -B for g.s. than 28 Si 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. JPS meeting in Kyoto, Toshi Gogami912012/9/14
7 Li(e,e’K + ) 7 He #1 Observation of 7 He w/ good statistics Fitting Result (40) JPS meeting in Kyoto, Toshi Gogami922012/9/14
-B = w/o CSB w/ CSB CSB effect by cluster model Four-body cluster model E.Hiyama et al. PRC80,054321(2009) N N Phenomenological potential JPS meeting in Kyoto, Toshi Gogami932012/9/14
7 Li(e,e’K + ) 7 He JJ -B [MeV] Cross section [nb/sr] SLAKMAID 1/ Theory by Sotona et. al. (Cross section) by Hiyama et. al. ( -B : w/o CSB) (1.3 < E < 1.6 GeV, 1 < K < 13 deg.) Result #1 ID-B [MeV] Cross section [nb/sr] #1-5.71±0.02 (stat.) ±0.20 (sys.) 31±2.8 (stat.) +11.8,-9.3 (sys.) Red : calculation with SLA Green : calculation with KMAID (40) JPS meeting in Kyoto, Toshi Gogami942012/9/14
7 Li(e,e’K + ) 7 He High statistics spectroscopy -B =-5.71±0.02 (stat.)±0.20 (sys.) for g.s. – Cluster model calculation -B =-5.36 (w/o CSB) -B =-5.16 (w/ CSB) Cross section : larger than shell model calc. JPS meeting in Kyoto, Toshi Gogami952012/9/14
E ~Count, S/N~ Peak ID# of peak [counts] # of BG(3 ) [counts] S/NSys. Err. (Contami. -%) Sys. Err. (Loss +%) 7 He:# B:# B:# Al:# Al:# Al:# JPS meeting in Kyoto, Toshi Gogami962012/9/14
JPS meeting in Kyoto, Toshi Gogami972012/9/14
JPS meeting in Kyoto, Toshi Gogami98