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  K K MC studies

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

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:  < [2.1 o, 3.9 o, 2.6 o, 7.5 o ]  < [2.4 o, 4.2 o, 2.7 o, 6.7 o ] AB BC CD DE 99.5% hits

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

MC: dE/dx E > 7 MeV only for negative stopping particles

Reconstruction of negative pions from experimental and MC data (Z vert > -7cm, <15cm) PR00: events ~41000 CENTRAL events ~17000 MB events PR01: events ~25000 CENTRAL events ~60000 MB events MC: events ~51000 CENTRAL events ~50000 MB events PR00 PR01 MC  #  MC sample contains 85% of negative pions

dE/dx calibration by negative particles

Calibration factors for: PR00 PR01 PR00+PR01 Plane A: Plane B: Plane C: (dE/dx) MC = 1.13 (dE/dx) exp

Candidate tracks are identified on M p and E loss plane (M p ) i = (dE/dx) i * E i ( 1/  2 ) (  m  2 ) E loss = Σ dE i /nhits, i=A-E PID contours E loss MpMp  p K

Reconstruction of experimental and MC data PR00 MC  K p ! Number of reconstructed particles depends on the (dE/dx) F veto (=1 MeV)

Reconstruction of experimental and MC data

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

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

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

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

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

Reconstruction of MC data

Reconstruction MC data