1. JLab hypernuclear collaboration meeting / JSPS Core to Core Seminar Study of elementary process in Hall-C p(γ*,eK + )Λ/Σ 0 9May2012 – 11May2012 Department of Physics, Graduate School of Science, Tohoku Univ. Toshiyuki Gogami

2. Contents Kawama-san’s results Derive the cross section by myself

3. Definition of the cross section Solid angle of HKS Average value The number of VP Including HES solid angle and acceptance

4. Contents Kawama-san’s results Derive the cross section by myself

5. 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] peakbackground B : Half width at half maximum C : Center value

6. Cross section of p(  ,K + )  PRC 73, 035202 (2006) R. Bradford, et al. This work (Preliminary) 227±12±26 nb/sr Q 2 =0.01 (GeV/c) 2 →Compared with p( , K + ) 

7. K + production at small angles electroproduction SL: 0.41 = 0.35 + 0.004  0.001 + 0.06 (  = 0.7 ) a steep Q 2 dependence ? P. Bydzovsky’s presentation at ECT* 2011 (  *,K + ) JLab Hall-A E05-115 W=1.9 GeV Q 2 =0.01 (GeV/c) 2 2012/3/25 JPS 2012 年次大会

8. Contents Kawama-san’s results Derive the cross section by myself

9. Current missing mass spectrum JLab E05-115 CH 2, ~ 450 [mg/cm 2 ] ~ 2.0 [μA] ~ 38 [hours]

10. Current missing mass spectrum JLab E05-115 CH 2, ~ 450 [mg/cm 2 ] ~ 2.0 [μA] ~ 38 [hours] Accidental Coincidence Quasi free Λ from 12 C

11. The number of events of Λ and Σ 0 5760 ± 125 (Integrated : -5 – 9 MeV/c 2 ) 1579 ± 94 (Integrated : 72 – 86 MeV/c 2 ) Λ Σ0Σ0 JLab E05-115 CH 2, ~ 450 [mg/cm 2 ] ~ 2.0 [μA] ~ 38 [hours]

12. Definition of the cross section Solid angle of HKS Average value The number of VP Including HES solid angle and acceptance

13. Momentum acceptance cut (Λ) HES momentum region 1.0.770 – 0.900 2.0.770 – 0.835 3.0.835 – 0.900 52 Λ V g.s. ~8.5 msr

14. Momentum acceptance cut (Σ 0 ) HES momentum region 1.0.770 – 0.900 2.0.770 – 0.835 3.0.835 – 0.900 52 Λ V g.s. ~8.5 msr

15. Concerned efficiencies Log book Simulation Data Data (E01-011)

16. Preliminary results Notice that several cuts are applied for HKS  Solid angle should be less than ~8.5 msr  Cross section is going to be larger This 0.6 JLab E05-115, Q 2 = 0.01 [GeV/c] 2, W=1.93 [GeV] Kawama-san’s results

17. Summary and Outlook Summary – The elementary cross sections is similar to the results of p(γ,K + )Λ from CLAS and SAPHIRE Outlook – VP flux – Precise solid angle estimation of HKS (and HES) Depending on Momenta and angles – Efficiencies Tracking, Trigger, PID cut – Effective target thickness – Burned effect  Compare to the other experiments (Hall-A, CLAS, SAPHRE) and theories.

18. 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] peakbackground B : Half width at half maximum C : Center value

19. Cut conditions to make the missing mass Cut conditions – 1.0 > NWC 1+2 – 5.0 < AC 1+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

20. 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

21. K + survival ratio after AC cut (CH 2 ) (accut,wccut) = (5,-0.1) pi suv. ratio: 0.0631439+-0.00148976 K suv. ratio: 0.876875+-0.00513167 p suv. ratio: 0.911427+-0.0023794 (accut,wccut) = (10,-0.1) pi suv. ratio: 0.105762+-0.0019663 K suv. ratio: 0.931211+-0.00536427 p suv. ratio: 0.94023+-0.00243485 (accut,wccut) = (15,-0.1) pi suv. ratio: 0.141455+-0.00231043 K suv. ratio: 0.956913+-0.00547386 p suv. ratio: 0.960014+-0.00247285 Stricter cut of AC NPE looser cut of AC NPE π+π+ K+K+ p π+π+ K+K+ p

22. K + survival ratio after WC cut (CH 2 ) (accut,wccut) = (2000,1.1) pi suv. ratio: 0.922368+-0.00752531 K suv. ratio: 0.987653+-0.00566791 p suv. ratio: 0.133889+-0.000701787 (accut,wccut) = (2000,1) pi suv. ratio: 0.963952+-0.00777583 K suv. ratio: 0.989093+-0.0056741 p suv. ratio: 0.176933+-0.000821917 (accut,wccut) = (2000,0.9) pi suv. ratio: 0.971601+-0.00782181 K suv. ratio: 0.999575+-0.00571909 p suv. ratio: 0.259314+-0.00102927 Stricter cut of WC NPE looser cut of WC NPE π+π+ K+K+ p π+π+ K+K+ p

23. 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

24. HKS efficiency ε HKS = 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 – f decay : 0.252 (± 0.006) – f burn : 0.82

25. Definition of the cross section SIMULATION

26. Theta and Momenta of the scattered electrons

27. Angular acceptance cut θ e’ > 0.05 rad

29. Back ground estimation Optimal scaling factor  1.08 Black + (Green × scaling factor) = Blue Scaling factor : 1.