1. HES-HKS analysis meeting 30 Aug 2013 Toshiyuki Gogami

2. Contents Cross section of elementary processes – Introduction – Correction factors K + decay factor H reduction Results Bucking coil

3. K + Λ, K + Σ 0 cross sections SAPHIR : K.H. Glander et al., Eur. Phys. J. A 19, 251-273 (2004) CLAS : R. Bradford et al., Phys. Rev. C 73, 035202 (2006) JLab E94-107 : P. Markoviz et al., Proceedings of SENDAI08 (2009) JLab E91-016 : F. Dohrmann et al., arXiv 0707.3059v2 (2007) γ (*) + p  K + + Λ γ (*) + p  K + + Σ 0 Preliminary 200 ± 16 ± 91 Preliminary 85 ± 13 ±34

4. Angular and momentum acceptance HES HKS W~1.93 GeV Q2Q2 θ K lab  θ K CM

5. Definition of cross section Solid angle of HKS Event by event The number of VP Including HES solid angle and acceptance The number of VP Including HES solid angle and acceptance

6. K + decay factor

7. Hydrogen reduction correction Figure: An photograph before and after the beam irradiation on the targets.

8. H reduction factor & Run selection 76313 136.74 76314 136.74 76315 136.74 76316 138.74 76317 138.74 76318 140.74 76319 140.74 76320 142.74 76321 142.74 76322 186.2 76323 186.2 76324 186.2 76326 185.2 76327 185.2 76328 185.2 76329 185.2 76330 185.2 76331 185.2 76332 185.2 76333 185.2 76334 185.2 76335 185.2 76363 165.2 76365 163.2 76366 163.2 76367 161.2 76368 161.2 76369 159.2 76370 159.2 76371 157.2 76372 157.2 76373 155.2 76374 153.2 76375 153.2 76376 151.2 76377 151.2 76378 149.2 76564 148.74 76565 148.74 76566 148.74 76567 147.74 76568 147.74 76569 146.74 76570 146.74 76571 145.74 76572 145.74 76573 144.74 76574 144.74 76336 185.2 76337 185.2 76338 185.2 76339 185.2 76340 185.2 76341 176.2 76342 176.2 76343 175.2 76344 175.2 76346 175.2 76347 174.2 76348 174.2 76349 173.2 76350 173.2 76351 172.2 76352 172.2 76353 172.2 76354 170.2 76355 170.2 76356 169.2 76357 169.2 76358 168.2 76359 168.2 76360 167.2 76361 167.2 76362 165.2 /data/8d/gogami/MM/mm23/krd/lambda_reduction/targetpos/tpos2.dat Target position from EPICS 78.6 ± 9.9 %

9. Procedure 1.One W bin ( W~1.93 GeV ) 2.Three Q 2 bins ( W~1.93 GeV ) 3.Two angular bins ( W~1.93 GeV ) An original ROOT file  1.Add necessary information Jacobian, HKS solid angle, K + decay factor 2.Derive the QF background shape from 12 C data 3.Subtract the background shape 4.Estimate virtual photon (flux) by a Geant4 simulation 5.Calculate the cross section with efficiencies and correction factors

10. Results Θ lab e [rad]θ CM K [rad]Q 2 [GeV/c] 2 Λ (CMS) [nb/sr]Σ 0 (CMS) [nb/sr] 0.030-0.0500.270.003166 (17) (32)55 (29) (10) 0.050-0.0700.260.007155 (18) (29)51 (30) (10) 0.070-0.1000.270.013159 (18) (30)81 (29) (17) 0.030-0.1000.270.007164 (10) (31)78 (17) (15) Θ lab e [rad]θ CM K [rad]Q 2 [GeV/c] 2 Λ (CMS) [nb/sr]Σ 0 (CMS) [nb/sr] 0.000-0.2500.200.007291 (32) (55)176 (12) (33) 0.000-0.2500.350.007176(12) (33)53 (24) (10) 0.000-0.2500.270.007198(12) (28)72 (20) (5)

11. 12 Λ B g.s. from CH 2 target 52 (15) (4) nb/sr Polyethylene target 101 (4) (38) nb/sr in JLab E01-011

12. Hidden factor, 2 ?

13. Paper of bucking coil to NIMA ( final procedure ) http://dx.doi.org/10.1016/j.nima.2013.08.047

14. Backup

15. Energy loss

16. K + absorption factor

17. Trigger efficiency

18. Charge distribution

19. H reduction