1. p/in BRAHMS at forward y Paweł Staszel Jagiellonian University

2. Analysis concept 1. the analysis utilizes the feature of same pion and proton acceptance in eta vs p T space in the same real time measurement. 2. for a given y bin we calculate p/π ratios on setting by setting basis (same real time measurement) separately for Tof2 pid and Rich pid. 3. in this way all factors like acceptance, tracking efficiencies, trigger normalization cancel out in the ratio. The only remained corrections are specie related which is geant correction (delivered by Flemming) and pid efficiency correction. Thus pid is a crucial part of the analysis

3. Rich 1. for Rich in first step we parametrize the rich inefficiency vs momentum by studying pions yields in tof2 for tracks with Rich_ring=0. 2. it can be done for low magnetic field settings (430, 608) but already for these fields one reaches the saturation value (~3%) which is then used for higher field settings --> (here we have to relay on that, that the rich is quite stable device at least over a given specie/energy period.)‏ 3. the result found for pions is then extended to kaons (and other species) assuming that Cherenkov radiation depends only on the gamma factor. Corrections: 1. the correction for pions is just the correction for the inefficiency (~3%)‏ 2. the veto protons are corrected for pion+kaon contamination, which is taken as:

5. Extending inefficiency to other specie

6. Two methods comparison tof2 pions with rich veto all tof2 pions

7. Inefficiency versus ring radius

8. Testing correction for veto protons

10. Tof2 Tof2 pid approach is similar to that described in Flemming's note on p+p@62 analysis: Rich(veto) information is used to determine kaons in the range where they overlap with pions which leads a relatively clean sample of pions.

11. Tof2

13. Tof2 in auau@200

14. protons with false rings

15. Results

16. p/π + at auau@200

17. Central auau@200 vs etaauau@200

18. pbar/π - at auau@200

19. Central auau@200 vs etaauau@200

20. auau and pp @62

21. 200 vs 62 for the same μ B

22. this analysis vs some published is

23. this analysis vs some published pp @ 200, η=3.3

24. backup