S-2S meeting

1. S-2S meeting Toshiyuki Gogami 4Aug2014 2014/7/29 @ Tokai, Japan

2. Contents • Missing mass resolution study • J-PARC/KEK tour (7/29, 7/30) • CAD drawing of water Cerenkov detector

3. Flow of Monte Carlo simulation Geant4 Geant4 POSI2 POSI2 Process gen Analysis K- energy loss K+ energy loss Missing mass reconstruction Momentum resolution Angular resolution Vertex resolution (K-,K+) kinematics

4. Particle generation • K- momentum: • 1800 MeV/c • K+ momentum: • Uniform • 1270 – 1470 GeV/c • K+ angle: • Spherical uniform • 0.0 – 0.26 rad • Assumed Ξ’s binding energy: • 7ΞH: 0.0 MeV • 10ΞLi: 0.0 MeV • 12ΞBe: 4.5 MeV Fig: Particle distributions in the simulation

5. Each term contribution to the missing massresolution Missing mass, MH (Missing mass に対する各項の寄与) Calculated event by event  Mean values will be shown in results.

6. Each term contribution to the missing massresolution Missing mass, MH (Missing mass に対する各項の寄与) Calculated event by event  Mean values will be shown in results.

7. Assumptions • K- momentum resolution, Δp1/p1 = 1.0E-3 • K+ momentum resolutions, Δp2/p2 • S-2S: 5.0E-4 • SKSPlus: 2.0E-3 • SKSMinus: 2.7E-3 • Angular resolution, Δθ = 2 mrad Gaussian function FWHM

8. Examples ( with S-2S, 9.3 g/cm2 CH2 ) ① ② ③ FWHM ~ 1.8 MeV FWHM ~ 3.7 MeV FWHM ~ 2.0 MeV SIMULATION SIMULATION SIMULATION Momentum resolution Momentum resolution Momentum resolution Target Target Energy loss correction

9. Missing mass resolutions (bug fixed)

10. Missing mass resolutions vs. Target thickness

11. Summary 12C(K-,K+)12ΞBe S-2S + CH2 ( 4.65/9.30/13.95 [g/cm2] ) + energy loss correction: ΔMH ~ 2 MeV (FWHM) SKSMinus+ CH2 ( 4.65/9.30/13.95 [g/cm2] ) + energy loss correction: ΔMH ~ 4MeV (FWHM) • The natural width was not taken into account. • dE resolution was not considered. • Effect of the inverse transfer matrix is zero. • Assumed resolutions are the following: • K-: , • K+: (S-2S), (SKSMinus), • Δθ = 2.0 mrad .

12. J-PARC tours with M1 students S-2S Q2 magnet 7/29@ J-PARC 7/30 @ J-PARC / KEK S-2S Q1 magnet S-2S D magnet http://www-nh.scphys.kyoto-u.ac.jp/~gogami/pictH/pict_e05.html

13. CAD drawing of prototype of Water Cerenkov detector (1) The unit is mm.

14. CAD drawing of prototype of Water Cerenkov detector (2) Experimental setup at ELPH The unit is mm.

15. CAD drawing of prototype of Water Cerenkov detector (3) Memo about text exp. Experimental setup at ELPH

16. Outlook • Simulation study with SKS (S-2S) spectrometer • CAD models

17. Backup

18. Missing mass vs. Energy loss in the target (9.3 g/cm2 CH2) SIMULATION SIMULATION Energy Losses of K- and K+ [MeV] Energy Losses of K- and K+ [MeV] Fitting with a linear function (test) Before correction After correction SIMULATION SIMULATION [Counts / 0.4 MeV] [Counts / 0.4 MeV] FWHM ~ 1.9 MeV FWHM ~ 4.0 MeV -BΞ + 4.5[MeV] -BΞ + 4.5[MeV]

19. Missing mass vs. Energy loss in the target (4.65 g/cm2 CH2) SIMULATION SIMULATION Energy Losses of K- and K+ [MeV] Energy Losses of K- and K+ [MeV] Fitting with a linear function (test) Before correction After correction SIMULATION SIMULATION [Counts / 0.4 MeV] [Counts / 0.4 MeV] FWHM ~ 2.1 MeV FWHM ~ 2.8 MeV -BΞ + 4.5[MeV] -BΞ + 4.5[MeV]

20. -BΞ vs. z 係数の差が起因

21. 入口で生成 散乱粒子のみ運動量損失 ex.) 0.85 * 20 = 17.0 MeV 出口で生成 入射粒子のみ運動量損失 Ex.) 0.93 * 19 = 17.7 MeV

22. z vs. θK Zが小さい程ボケる(多重散乱の効果)

23. z vs. dE Zが小さい大きい (多重散乱の効果でpath lengthが伸びる)

24. -BΞ vs. dE ランダウ分布の尾

25. ミッシングマスに対する各項の寄与 p:p_{K-}: 0.64702 * 0.001 * p_{K-} = 1.16464 MeVp_{K+}: -0.585224 * 0.0005 * p_{K+} = -0.376266 MeVtheta_{K}: -174.443 * 0.003 = -0.523328 MeVmt/mh=0.709892Li7:p_{K-}: 0.901301 * 0.001 * p_{K-} = 1.62234 MeVp_{K+}: -0.832483 * 0.0005 * p_{K+} = -0.569078 MeVtheta_{K}: -61.0734 * 0.003 = -0.18322 MeVmt/mh=0.943207B10:p_{K-}: 0.91983 * 0.001 * p_{K-} = 1.65569 MeVp_{K+}: -0.849297 * 0.0005 * p_{K+} = -0.584822 MeVtheta_{K}: -43.6951 * 0.003 = -0.131085 MeVmt/mh=0.959847C12:p_{K-}: 0.926545 * 0.001 * p_{K-} = 1.66778 MeVp_{K+}: -0.854374 * 0.0005 * p_{K+} = -0.587025 MeVtheta_{K}: -36.6518 * 0.003 = -0.109955 MeVmt/mh=0.965867hyperdragon3: /home/dragon/POSI2/analysis/root/mmreso_contribution/Toshi Gogami , 24July2014After bug fixed in the calculations.

26. Pedestals for Cerenkov detector

27. Missing mass resolutions vs. Target thickness