Slow particles reconstruction

1. Slow particles reconstruction R.Hołyński, A.Olszewski, P. Sawicki, A. Trzupek, B.Wosiek, K.Woźniak • Algorithm description • Large dE hits • Angular cuts on track candidates • Negative particles as a “source” of dE/dx calibration • Mass parameter contours (PID) • Reconstruction of experimental and MC data • Slow tracks in PR00 data • MC study of reconstructed slow tracks sample • Search for f K K • MC studies

2. F X[cm] E D C B A Algorithm description We are looking for particles which range out in plane E MC min. ion. From the data hits with large energy losses in planes A-E are selected:dEi /dx > 0.5 MeV Z[cm] pp  50 MeV/c, pK 140 MeV/c, pp  200 MeV/c

3. Algorithm description • Hits with large energy deposits are used to form 5-hits • tracks candidates (one hit per plane). • Track candidates undergo angular cuts: • | i+1 - i | <  • (i, i from vertex position) • | i+1 - i | <  • MC:  < [2.1o, 3.9o, 2.6o, 7.5o] •  < [2.4o, 4.2o, 2.7o, 6.7o] • AB BC CD DE • 99.5% hits

4. Negative particles as a “source” of dE/dx calibration

5. Negative particles as a “source” of dE/dx calibration MC: dE/dxE > 7 MeV only for negative stopping particles

6. Reconstruction of negative pions from experimental and MC data (Zvert > -7cm, <15cm) PR00: 58000 events ~41000 CENTRAL events ~17000 MB events PR01: 85000 events ~25000 CENTRAL events ~60000 MB events MC: 101000 events ~51000 CENTRAL events ~50000 MB events PR00 PR01 MC # - 7372 145 MC sample contains 85% of negative pions

7. dE/dx calibration by negative particles

8. dE/dx calibration by negative particles

9. dE/dx calibration by negative particles

10. dE/dx calibration by negative particles Calibration factors for: PR00 PR01 PR00+PR01 Plane A: 1.12 1.14 1.128 Plane B: 1.15 1.13 1.133 Plane C: 1.14 1.14 1.127 (dE/dx)MC= 1.13 (dE/dx)exp

11. Eloss Mp Candidate tracks are identified on Mp and Eloss plane (Mp)i = (dE/dx)i * Ei (1/2) (m 2) Eloss = ΣdEi /nhits, i=A-E PID contours p K 

12. Reconstruction of experimental and MC data PR00 MC   442 502 K 55 81 p 28 104 ! Number of reconstructed particles depends on the (dE/dx)Fveto(=1 MeV)

13. Reconstruction of experimental and MC data

14. Reconstruction of MC data slow pion = pion having hits in A-D or A-E

15. Reconstruction of MC data slow pion = pion having hits in A-D or A-E

16. Reconstruction of MC data slow pion = pion having hits in A-D or A-E

17. Reconstruction of MC data slow pion = pion having hits in A-D or A-E

18. Reconstruction of MC data slow pion = pion having hits in A-D or A-E

19. Reconstruction of MC data

20. Reconstruction MC data